GENES A N D FUTURE PEOPLE
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Walter Glannon
A Member o f rhc Rrseus Bocrks Group
All rights reserved. Printed In tlie United State5 ofAmerica. No part of this pubhcation ~ n ~ be t y reproduced or rransxn~ued11-1 any forln or by Any nteaxa, eleccronrc or ~llecfia~~ical, including photocc)py, recording, or 'tnji intt>rrrr~tion storage dncI retrieval \)..stem,wlthout penn~ sionIn wrxtmg from the. pt~bI~sl~er. Copyr~gI~t 2001 by Wesrvlcw Prcss,A Mtrnber of tlzc l;"c.rse.~rs I3ooks Group Wcsrv1e.c~Press books art: avddable at special d~scountsfor bulk pu~lzaresIn tkzc Unrted States by corporationr, insdtsrcions, and other ~ r g ~ i i ~ l z d t tFor o ~ ~Inore s , inforlnatlol~,ple,~se contact the Special Msrkets Deirart~lle~lt at The Perreus Books C h u p , 1 l Ch~l~bridge Center, Gaxl-tbridge MA 02 142, or CIU (617) 252-5298. Publxshed m 200 1 In tkzc United States c?rfAmerica by Westview Press, 5500 Central Arvre~~ue, BuulcIer, C:oIorado 811301-2877. A I I ~in the United Krngdt>i~i by Westv~ewPrer$, 12 Hid'$ Copse Rc?rad,Cunlnur Hill, C>xford OX2 9jj
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For Ec-Ft4ill
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Introduction f The h a c h o f Genes: Biology, MetapEtysies, Moraliq
Genes and 13isease L3iolagical and Persol~alI d e n t i ~ Two Senses o f "Life" How I=;encs InArxencc the 1deiititic.sof 1"c.rsol.rs Mural Iniplications C:o11cfusion
2 Genetic Xnhrmation, Obligation, and the Prevendon of Lives G e ~ ~ e t'TiPstix-zg, c Screening, ar~clI n f o r ~ ~ ~ a d o i ~ Maral Asynlmetry and f-farnl Life Stages Should S o l ~ ~ e L3c t3revented? Lives I=;ivil-zg llriorit)r to the WO~SC C M C:o11cfusion 3 Gene Therapy and Genetic Enhancement Gene Tl~erapy:Pmbtetm and a hraciiox Access dncS Aliacatian Xss~zes G e ~ ~ e tEi cI I ~ I Z ~ I I C ~ X T I ~ ~ I ~ Negdtive and Positive Erxgenics: Is There a Slippery Slope? C:onclusion
4 The Morality of Human Cloning
Biolqica! Factors Means and Ends C:loning Body Parts Eugel"ics Again? C:c->nclusic>n
5 Extending the Human Life Span Cells and Sexzescexlcc An Evolutionary E&&-ON: Intergener~tionalEqtlality and Fairness Prudei~tialConcern About the Futt~re ConcSusioi~
Sox11e of tbc ~natcriaiiiii this book was prcscntcd to philosophy departillents at the State Univcrsicy of NevvYc~rkat RuEalo and thc University. of Western C>ntaria,as we51 as ta arzdienccs at the Facult7y of Medicixie of the U~liversiqof Calgary, the Joint Centre for Rioetilics of the t i ~ ~ i v e r s of iy Rmrito, tlre aiixittal cunfererlce of die Sociev for Applied Philosophy i n Manchester, U.K., a bioetbics conference at the Universiq ofTennessee at Knoxvde, and nleetinp of t l ~ eC:anadian L3ioethics Socieq in Edmonton and C>uebec City, X am grateful to all of these audiences for their canstructivc criticisins a11d s~ggestioi~s. I taught a graduate sciniliar 011 this topic in tbc 1\7iiitcr term of 2000 at f\/fcC;fi University a11d thank thc studcrits &or discussixig the philosophical aspects of huma1.r genctics at such a high Ievcl. T h e first dr& of the ~x~anuscripe was written tvhile I tvas a fellow at the Institrtte for Ethics of die Alxrericall Medical Associatioii ixi 1998-99, X thallk the Institute for the feilokvsiiip stlppnl-t I received and esptzcidy LirlcZa Ernan~lela l ~ djessica Berg for px-otecting nly research and cvriting time cvhde 1 w a s at the. AMA. T h e two anonynlaus readers conlnlissloned by Wesevie?~Press, as cvelf as Jan Heller, gave ine very helpfill colainerits on a11 earlier drak of the entire i~~anuscript. tainle Friedman lkoss gave lnc extremcly coi~strrrctivecriticisins on drafis of chapters 2 and 3.1 also bcriefitcd fro111 thc c o r n ~ ~ ~ eof nts Jeff McMalraxi,John H ~ r r i sand , two anoxiylrraus readers for the Jc?umal c?fAWrdicirzcdird I3tzilnstqllry on diEerent parts of ctidpter 5. Some sectioxis of the book's chapters lzave appeamd as articles in journals. Tl~eseinclude "Genes, En~bryos,and Future People:' Biocrlritlc t 2 (1998): 21 1-25; "The Ethics o f H t l m ; l ~C:toning:' ~ I ) u l i i s Quat-t~dyt 2 jl998) : 63--79;""ientity, hudential C:oncern, aixZ Extended Lives," BUiocfirii.~(hrtbcoming 2001);and '"xtending the Human Lib Span:'-fi~rirnrrI cfilii~idicillc c r r d I%iIc?soj~h)l(fi~rthcoining2001). A section of chapter 3 appears as "Iiitemening &orMcciical lkcasons," ixin EErc.li& Almond and Michael Parker (eds.), Etitic~~l huts ifl rltr Mu) Ckl.retics;Arc C2elres Cis? (Aldershot: Ashgate, 2002). I tharik
tbc pulzlishcrs of these jourilals a i d Ashgate Przk?lishi~zgLtd. for permission ta use this ~natcrial.Sarab wgr~~cr,my editor at Westvic~v,1\7as very supporrive of the pm~ectkofn the tirnc I first stthrnitred the book pmposal. f i r patience and wise gridancc are gready appreciated. Finally, I IXTI gratef11I to my wife, Teresa Yec-Wi Yu, b r her iilspiration and b r gracing my life in so many beautiful mr2ys.
Ikcccnt advances in human genetics h ~ v egive11 US the ability to i ~ ~ t t e r w ~ ~ e in tbc process of hurnai'r bic3logical dcveloplnent controlled or influericed by genes that extends frotm zygotes rind en1I3ryos to persons. One type of itlterventiolz is gez~eticdiagllosis of e m b r p s created through in vitm k r tilizdtio~~ (XVF), befixe they are trai~sferredto ancl irnplant it1 the uterix~e cw~U.,Thesecan be tested &?r genetic mubtions that cause or make tis susceptil4e to disease, This gives prospective parents the choice. betkveen allocvitlg an embryo to develup into a person with tltc risk of haviltg a sevcrc disease o r disabihty, o r selectively terr-r.li~~tating any f~lrtber development of thdt c~nbryc~. Alternatively, soon it may become possible to al of gc~ies prevent, coi'rtrcd, or evcrl curc discdses 'by delivering ~ ~ o r mcopies codirlg b r critical proteins into cells so that they will ftixlction propedy. It even rmy becorne possible to mar~ipulategenes in order to enhance peoplei dl-eady ~lorntallyhnctiolzing plysical, cogllitive, and emotitrtlal traits. All of these ibrnls of genetic interventioil give m considerable control over how m a v people will exist, when they will come into existence, their identities as perm11$ and the length and quality of their lives, In thxs rt.gan-1, qriestions about burnai'r gcnctics are inextricably linked to "geiiesis" qgtiestioi'rs 111 philosophy ~II Project was crcatcd in 19cCSC3by the National ReThe H L ~ ~ I IC;cnolae search Corrxlcil of the Nadonal Acaclerl~yof Seierlces ancl die Congressiotlal Oeice ofTechnoloLwAssesstnent. Its goal was to map rind seqtletlce the entire hzilrtan genolzte. 'To oversee this project, the Nat.io~lalInstitutes of Healtlt established the Natioilal C:entcr for Human Genome Research. Its m n & t e included the use of a small perceiltage of the Human Genome PrctJect's fiiilds for assessmeilt of and education on tlte ethical, leg& and soencial implicatioi'rs of humai'r gcnctic research, While tbc ELSI prc~~ect colapasses t h r c ~arcas of coi'rcern, legal and pcfllicy iss~lcshave stroi'rgly influenced the formulation and discussioi'r of the ethical issues pertailling to htixxrar~gcnetics.TIlese issues hinge largely on die trse of gclietic ixlfor~rra-
tion acquired through testing and screening prograxlls, and they include privdcy, conGdentiality u~llatvfuldisclosure, and coi~scnt.A major rationale ii>r fonndating prthlic policy g~idelillesand ezlactiilg legislarion in tliese amas is to protect ir~dividtralsfrom discritl-lir~ntimby pmspective insurers For example, one who or e r ~ ~ p l q e on s s the basic of genaic inforr~~at'jox~ has tested posiriw f i r a disease-causing gene and wltose meddcal record is p~xbliclyaccessible may find it difiicult or eve11 i~Iprr)ssib~e to obtain lik and health insurance. t3ecatxse insurance operates on the idea of pooling risk, and the gc~leticallybetter off Inay not want to pc301 their risk of disease with the geiietically wcjrsc off, the latter may be rcjcctccl. hy instararlcc coiapanies. Frxrtl-rerr~~orc, if gc~leticinformation were rctluired when applying for- work9then e z ~ ~ p l o ywho r s pdy the healtll care costs of their ernployees rnight rei'iise to consider one tvlto lids tested positive b r n gexle that only predisposes one to diseclse,I Although the legal m d policy implicatiours of genetics are of enarmorxs i n ~ p o r t a x en, ~ ycancer11 in this book cvrlf not be cvit11 tl~em,Nor cvrlf X address the issue of behavioral genetics. For the question of whether or to what extent gclies infucricc or detcrr~Gnchow humans act is so complex and controversial thdt it desemcs to be discussecl. separatittely"~zstead, I 1vill fiocus on a p'trticular set of philosophical questions generated by genetics. I believe that these qtlestiozls are more intrig~ingrind weightier than legal or poiicy qtrestiotls, in the sense that they can h d p us to achieve a deeper txnderstancSilt~gof our xlaturc as hrxxxrax~being axlcl persoxw, as tvell as of orxr moral obligations to tilture generations. More precisely, the book explores al questions pertinent to genetics, one. two relatecl g e ~ ~ e r philosopl~ical metaphysical, the other moral: (I) How do genes, and diRerent forms of genctic intcrv;ention (gene therapy genetic enhanccxnent, genctic diaglosis of p r e i n ~ p i i a ~ t cmbyos, io and so 011) a&ct the icientities of the people l Hov,~d o these 1x1who already exist and thosc we bring into e ~ s t e r i c c (2) terver~tionsbenefit or linrrn the people we bring into existence in the near f~itrrrcand those tvllo tvill exist in the dista~lt:f~iturc?It is m r t l l rdisix~g lztore spccif;rc q~restionsgern-taxle to (2). Are we lztorally obligated to prevent the existence of people who would be sevex-ely diseased and disable$ h the claims oflteopie cvho wiU exist in the distant filtui-e have less moral weight than the claims of those who wrlf exist in the near futux-eWorzld gciietic enhal~ceiaeritof cognitive, physical, and emotiondl capacities to raise them above the normal lcvc1 of frInctioni~zgfor people be illorally ol>jectionalzleand, if so, on what grc~unds?Hc3\\7 could \VC ensarc equal and
gair access tct both therapeutic and enhancexner~tgenetic technologes &or all people? M e t h o d i c itz each of the five chapters I first lay out the rele~1r.g biological or ~rtedicnlfacts and possibilities itz~7olving~ n e r i c and s then explore the ~rteraphysicalarzd xnoral inrplications of them, especially as they pertain to personal identity and our obligdtims to future generations. 1 have tried to make the discussion biologicauy and medically informed to give n3ol-e. substance to tlie phdosopliical claims and arpnlents. t3t-tilosophers frequently ignore or ctvcrsinlpli6 scieiicc in their discussions of i~~etaphysical and i ~ ~ o rissues, al often engaging in hypcjtheticdl thought-experin~entsthat are overly speculative and lachng in piiausibiliy outsiclie of their c m n field. It shorxld be notecl, however, that rlly rllait~coslcersz is not wit11 bioloti5.y:~ and rlledicine. JXather, X refer to these areas oxzly as a xzecessary (hut not stlfiicieszr) basis on which to intelligibly discuss tlie fiilosophical isstxes. Moreover, some of the ideas I explore involve what presently may seem to be renlote biological ar1c3 n~edicalpossibilities, These illclucie genetic enhancen~ent,human cloning, and extending the h u i ~ ~ alife n span on a broad scale. Nevertheless, it is instrrrctivc to consider tbcse pos"lhities in order to test and refine our i~~etaphysicdl and moral intuitions. It is particularly in~partantto do this because all too often our xxraral attitudes arzd laws lag 17ehit1d biotechnoloti5.y:Axzcl mther than being breed to r e x t to biotechtzological fit~dings,we can more eEectively address the philosophicaf aspects of ftrttrre findings when they occur by mticipating them in advance. Not too long ago, cryoprrtserv%tiol7tionof embryos, clonillg of animals, xenotransplant-dtioi~>and gene therapy to treat h ~ r n ~ adisea~es ll were unthillkahle to many people, Although now these prcjccdurcs arc actually practiccd, we still have not sctrted out aU of tbc 111oral issucs gcriIlane ta tl~em. In tbinkng plilosophically about gcl~esisqtxcstions, I have been inflrxencecl prirllarily by the work of philnropiierc I:>erek and I3avid I-leyd, especially with respect to the xzatrlre and exterzt of our obligations to i'iittrre gcner~tioszs.3The work of Philip ktclter and JefF McMahan has influenced n ~ ydisctrssioi~of other pliilosophical questions generated by human genetics.Wy px-esentation of the biislogcal and medical issues has been shaped by the theory of evolutiai~arymedicine, especiaJl.y- as explainccli in tbc wtjrk of C;eorge C:.WiDiams and lworkit~,""ethics . . . ir-zclrxdes convictiax~sabout wllicll kincls of lives are good or bad for persolls to lead, and morality incl~tdesprinciples about how a penon should treat other people.'" Because of its social content, ""morality" better captures the normative aspects of genrdc technology; and accordingly 1 will use this term instead of "ethics" "tbughout the book. At a lt~wcrlevel of arguxnerit, I do 110t adopt a s-i~iglcmoral tbcary to address tbc difTereiit issues in tbc chapters but instead use dikFerciit theories to support diEerent n l o d concltlsioi~s,My reasoil b r doing this is to avoid a ""tp-do~vn" zxlethoci where I e r ~ ~ d o01y1s theory from the outset and sirr~plyapply it to every moral aspect of gellcttics coverecl i n the bonk.Tlzis would run the risk of artificially fr3rcing the issues to tit the theory. More impor"i"lntly,it mrould ignore the f ~ c that t different questions have been raised about diffexnt moral implicatio~~s of human genetics and accordal that is sc~lsitiveto these diEcrenccs. For examingly recyuire i ~ ~ o raiulysis pri~icipleill ch'jptcr 2, plc, xny discussioi~of tbc inipersolldl coi~~l~arativc regarding the quality of tbc lives we bring iiita existence and mi~iiniizil~tg the arnount of pain and ntffering in the world, is maivated by co~~sequen-
tialism. In col~trast,ill chL%pter 4 the principle that human clolies must not by be treated solely as Incans hut also as ends-in-thcrnselves is i~~otivated Ka~~tiatlisrn, or deontoloCq.Sin-tifarly my argilrtetzt in chapter 3 agaitlst geof peoptek coglirive capacities to improve their health netic rl~ali~ip~tlati~n statrls is gro~rlldeclin dcolltological reasot~ing,The two theories in question are not entirely antithetical, Coi~ten~porary noncoilsequentialistf in tlte Ka~ltla~l traditiaiii ltold that in sanle cases cve arc pernlitted not to maslmize overall best consequences, and that in other cases there are constrail~tson pro~notingthese conseqrxcnces.YTbis in~pliestbat col~scyucriccs d c ~matter moraLly and can be promotccl. to a ccrtail~textent. At a higher level of arhurIIent, my gelxxzal concern in all of tbc chapters is xvitb how people can benefit 60n1 or be hdrrned by diEeretlt farlrts of genetic interkrentiot~.In this regad, my genet-nl theoretical oriei~t;atiot.~ is a c o ~ ~ s e q ~ l e n tialist one, The structure of tlte book is as followrs, In chapter 1 , I lay out the basic features of human genetics, explain the role that genes play in disease, and &scuss how tl~esebiological features bear 011 the idelltities of persoils and our moral olzligations to the peaplc xvc bring into e,urtstencc.C:hdptcr C! G>cuses more closely on moral issues, specifically what the genctic 111forl11atiox~acclrxirerl. through prevmptomatic gclletic tcsdlig of adolescents and adults, as well as pmintplantntim gellcttic tliagllosis of e ~ n h r p simplies , for our obligdrions to existir~gancl firture people. I consider whether tl~erc,are diseases that make people's lives on balance not worth livitzg, and whether this entails a moral requirement to prevent these lives and the existence of tlte people wlta would have tltcm by terminating genetically d e k c t h e enll-tryos. Early- and late-onset genetic diseases are considered in tltis re7 tbcy arc at risk gard. Also pertincrit bcrc is whether people who k n c ~ ~tbat of hdvi~lga latc-onset geiietic disease as a result of presymptomatic tcstil~tg have a11 otlligation to sharc tbis il~tforinaticrx~ with family i~~emlzers who also may be at risk. In chapter 3,I exclrniiie two otller farms ot'gcnetic intewet~tio~~-gem therapy to treat diseases, 2nd genetic enlla~~cen-lent of cog~litive,plysical, and emotiollaZ traits and cayacities. I analyze these procedures in terms of benefit and ltarn~,pernlissibility and irnyerrnisstbitity~ar1c3 equality and Fairness regarding access to them. Because the eKects of germ-line genetic i~~anipulation will bc passed 011 to ofhpring*and bccause it is not known what tkcse effects i ~ i g hbe t in tbc l o l ~ gterm, generally there arc" sound biological ancl lnoral rcasolls against this type of intcnrention. In soiaatic-ceH gene dlempy, on the other h a d , the eficts rernnir? with the individ~~al
who is treated. Although it is medically and xnorally desirable, soiaatic-cell genc theralfy h a bee11 ~Kcctivein treating only a Ec.v.7 discdses and has res~rltedin some deaths. fnsot;ar as all farrrls of gerlcttic intervetztiotl are desigr-tcd to !?revers, control, or c u e disease and disabilie): the gerlctrral failttrcr. of sontatic-celt gene thertlpy provides an even strollger case for testing and selectively tern~inatinge m b r p s with genetic dnomalies ca~rsingsevere disease and disabilit)l;With these same medical and moral goals in mind, X give five 1-easonsagainst genetic enhancement. C:bapter 4 is an analysis of clonirlg b u i ~ ~ abeings n and humail body parts. I xnail~tailitbat there arc few c~>mpellil~tg biological reasons for cl~~nixlg full-Aedgcd humans, and that cloning body parts would sidestep i a a ~ ~ofy the rr~orniqualms generated by the idecl of fitrrr~anclorzir~g.Nevertheless, f argue that corlcerrls about the loss of persorlal autoncltxly and digllity throtrgh hurrlan cloning are ur~tittrrlded."l:'hesebasic humall values may be threatened by tlte purpose for wlticlt cloiling is used, but not by tlte procedure itself, wltich does not necessarily imply the violation ofonr lttrmanity or personhood,There are two main nloral concerns about cloning tltat hvctlve potential h'jrrl~to people. First, 13NA &laagc in tbc dollor cell nucleus could result in premature agil~tgand disease in clolied people. Scco i ~ das , an asexual forin o f ~ p r o d u c t i o nclonirlg , prdcticed on a broad scale c o d d adversely affect genetic divetrsiy and conseqt~entlythe ability of fbturn people to adapt to and stlwive in chalgir-rg physical envirorlmerlts. tfecazlse of this, and because gerletic ~xtaterialis transferred frolxt the donor cell nucleus to tlte oocyte, there are unique s n e t i c katures of cloning that dstinpish it h m otlter farms of assisted r e p d u a i o r r . Xn zclsponse to the claim by some that widespread lttrn~anclorling is a f.dncifill idea, I suggest tbat xndny parents night bc illclinccl. to resctrt to cloliixig to prevelit disease in tbcir children, I then paint out the adverse inipact this practice could have on futurc people. In chapter 5, 1 explore the pmspcct of extelzding the hzl~naillife spa23 throtrgh genetic rr~a~ltpttlatir,~ of the rr~etrhanistnsof i~girlgin gerler'11 ancl t&n-leres and etnbrpnic stelxt celjs in pdrticdar. f explore whether this pr-ocedut-enlight ix-rcrease the. nun~l-terof deleterious n~utationsin ltuxrlans and how this migltt affect the ability of people in the distant future to have a reasonably long and disease-li-ee life span. Moreover, I consider wltat increased longcvit)r would iIIean for our prudcritial concern alzout our hturc selves, as WCU as its c~llectivcefFects 011 populati011 and the quality of people's lives.
The g c ~ ~ e raim a l of t h s book is to move philosctphcrs, biocthicists, bicdogists, a i d readers 111 general to rcflcct 011 tbc philosophical questions gcner;cled by digerctl~taspects of hrrlrtat.1ge~~etics, These q ~ ~ ~ l ' i include o n s the extent to which genes a17d differex~tfarms of gej~eticintexventiot~irzfltrence whether we are healthy or discnsccl, our idex~titiesas persons, the qudjty of our lives, and our moral ohligdtions to people in ftxture generdtions.
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Genes are stmtches of xltlcieotide b d ~ epails cllos-rg s t r a ~ ~ dofs the 1:)NA xxralecule, die xxrajor coxrrpos-rcxlt of each chrorxrasosne. They specify the arnitlo acid seqtleslces of strl-tcnrral ancl enzyn-latic proteins corltmtlix~gthe fl-tncti.ons of simple and multiceliular organisn~sh m bacteria such as L3. coli to humans. Genes are the basic units of heredity thmuglt which the biological cltaracteristics that define us as hrlmans are transllutted from one generatio11 to tbc ncxt.l While alf humail organisins sharc thc sarnc basic genetic code, variations among different alfeles, or forins of gcnes, distinin our species by produciiig differguish each of us h m other i~ldivich~dls erlces in our p t i e n o ~ p e the , sec of our &sewable traits. Thcse g a l o ~ p i c p a l y ~ n o r p h i s ~play ~ ~ sa xn;;?lorrole in shapir~gthe unhtle biohgicaf icierltitry of each humdn orpnislxr, But while genes influence our biological functiovls in nrany crucial respects. they do not by tltemselves completely determine otrr biological Fate. For haw cells firlzction at the molecular level depends to a great extent on how the gei-zes in these cells iiiteract with certain chei~iical processes inside our bodies and brail-rs,as well as xvitb variotas enviroi~i~~entiil Eictors. These include not only ioruzingr radiation, viruses, and bacteria, hut afso diet: and marlipuldtion of gesles throtlgl~different f'orms of hiotechnolo~.V~rrrther~xtol-e, tvhile gerles iniltleslce the structures and f~ir~ctions of orxr bodies dncS brains x-rccessary to gellerntc dncS s u s ~ i nthe consciousness and mental lik that make us persons, genes callnot oEer us a complete explanation of the psychological conceptr; of personhaad and personal i d e n r i ~thmuglt time. Nor c m genetics tell us what is morally perinissible or Inlperr~Gssible,or xvbat constittrtcs beliefit and l ~ r r nwith , of gclles in thc soxnatic or gcrm cells to prerespect ta thc i~~anipulation a l These vent or eiihance tbc exprcssioi~of ccrtiiiii physical and i ~ ~ e n ttraits,
questions cannot be raised and airalyzed within tbe dc)~nai~i 06 gciletics alone, Nevertheless, arl exarrlir~ation of the stxbtle and coxrtplcx tv;kys in which genes cazrsally inAlretzce the rlatrrre of Irrrtrtar~h i & % ~and personal icierlcity*as well. as ltovv they can bcs.lefrr: and fiar~xrus, car1 elucidate such questions as,What docs it mean to be human? What is a ""prsoir""3re we essentially hunlan orgarrisnrs or persons? What obligdtions do we have to prevent, treat, or cure diseases in people by ilrtermnitlg at tlte nroleczrlar genetic level? Hovv I ~ ~ I I ' and )P whdt sort of people should we bring into existerice in the near and distant future? My aim in tbis chapter, and Inore gencraLZy tbrc>ughout this book, is to address these qrxestions by explorillg the inf-lzrerlce of gerles along biological, metaphysical, and ~rrnraldin-rerlslorls, Aittlough they are i~lterrelatedin inrporrarlt respects, each of these three dir~~ensions is necessary but not sufiicient &?r a satisf~~rrctory account of tlte other two. An tlnLJerstaxlni~tgof the biological features of our bodies and brains is necessary to explain how co~rsciousnessand otlter nlenta't states idcntificd with perx3nnhood ancl. pcrsoilal identity throtxgb time can elncrgc and be stas~iii~i~d. But biolc~gicalfeatures alone ca~rirotaccoulrt &or tbe contents of these mental states or tbcir pheno~aenological,qualitative character. Similarly, an t l r l i l e r s ~ ~ dof i q the ~xretapliyicsof pel-sorlal identity is x-rccessary to accottrzt for the xrtoral ~lotloxlsof bellefit ancl hanrr, For only beings with klterests can be harmed, and liavirlg interczsn pstrpposes the capacity &?r consciu~xsnessand otltcr b r m s of mental life that define perst?irs. Still, this metapltysical notim by itself cannot fillly explain the moral significance of benefits and harms, or why benefits to some people call oum7cigh, or bc ouhveighed by harms to others. I will collsidcr these tbrce dilaensions in turn, sho\\7ixig how each ilzfluenccs the others, with further elaboration and rcfincment of tbc llaturc of their interrelations in strhsequerlt chapters. The geneticist Tl~eoclosirrsI>ol-tzl~arwkyclaixr~edthat ""xothixlg in biology lrtakrs sense except in the light of cv~)ltrtion."~~ In adopting this posithat questions about genes and tlteir inlplicdtions &?r tion, I will mai~ltai~l the nletapltysicaf,and moral isstles X have mentioned should be raised and analyzed. mrithin a fiametvork of evoltitionary biolom. O u r bodies, inrrllunc systcms, brains, and rl~entallife have developed over a long period of evc)lutionary time and arc integrated parts of a d e s i g ~iraturailly sclccted to confer a survival advantage on humair org~nismsin different pfi)psical ci~virorlrrlexlts,We have beer1 desigrlecl as orgzinisxrrs dimttgh natural selection
ta survive in ordcr to cribar~ceour reproductive &tizess sc:, t h ~ our t gclles can be ef6ciently and ckFectively transmittccli into the next generation. Hiological f.itt:~essis rxcessnry for reproductive success, Unforttrnntely, for persons with the desire to have longer Eves, the ~7rotecdox1that genes aEor~4 our orpnisl~tsfut-3rrtacme diseases earlier in life makes our orpnisl~tsr ~ ~ o r e vulnerable to chronic diseases later in lift.. I will pay closer attentiolz to this trtde-off and what it implies fir- extending the h m a n life: span tltltrot~gh genetic manipulation in chapter 5, It is one thing to cxplaili tbc in~personalnature of gciles 111 tcrrns of evc3lutionary bic>lo~y.It is quitc another to show hmv gclles can akFect the iclientitiies and intcrcsts of persoi~s.I=;encs should bc understood as operating at two distinct hut related levels. O n a get:ler"aIle'17el, Fries i'iitlction acc o r d i q to prirlciples of natural seIection, e~lhancinghuman stlwivai and repmductive fie~lessso that they can be pasecf 0x1 kern one generation to the next, For ltunlans and otlter species, tkrs process takes place over many generations and involves extreme1): long periods of time, O n a particutdr level, genes aRect human orgdnisnls and persons over sltortcr periods of time by controllirzg thc synthesis of proteiris that underlies the ccll~l;;~r functic>i.rsof our bodies and brains.. Insofiar as our xncntal life causally dcpenas on tbc strrrcturcs and hnctions of our bodics and brains, and gclles it1flues:lce these structtlres arld f~itlctions,ger:xs irldirecdy shape our understarldiilg of ourselves as self-corlscious individuals persisting through tin-te. Moreover, by contrc>lllng cellular ~ztecbanistl-tsger:xs play a causal role in the etialogy of hea1th.y and diseased conditions, depending on cvhether tlte deles of these genes are normal or mutated and tlte extent to which mutations aRect these mechanisms. Iltecause persons haw an interest in being bcxltl~yand avoiding discase, because berie6t and harm arc defined in tcrrns of the satisEactio11 and dckat of interests, and bccduse gencs play a causal rc:,le in hcaltlz and disease, gencs c211 illdirectly benefit or harm persons, So, while the 11ealth or disease that individual prsorls experie~lceare not directly cmsec?,by the tvzy genes operate at the e\70l~ttiot.larylevel, they are die ixlc1il-c-cteEects CA?the force of r~atrtrnlsclectiox~. In the 1-emainderof this chapter, I first discuss the connection b e ~ e e n genes and &sease,Then 1 go on to distinguish the biological type "hunlan organism"' or ""human being:' from tlte psychological type "'pcr-son" and arhwc thdt we arc essci~tiallypersons. I explain t h ~ thcsc t two ontological types correspond to distinct biological and psychological sellscs of ""lc'" a i d that each of these types h a disti~~tct criteria of iclientity. III addition, I explain how genes and wrious fonrts of genetic interver~tioncar1 affect the
iclientitiies of persons.. Findlfy, I sketch some of the xnoral issues for discussion in sl~zbseqrxeiitchapters per~iiningto tbcse intcrwntioiis, addressing the more general qucstio11 of what our obligations are to the people we bring into existence in die xlear dncS distant: ftitrrre.
Genes and Disease The Hlxmari I=;eii~iaePrcjjcct 1 ~ a screatccli ill 19cCSC3on tbc joint rccomi~~en&tion of tbc National Research C:ouncil of the Nadoiiat. Ac2dc111y of Sciences and the C:oiigressiondl Office of Technolog~Assessmerit."ts a i n ~ was to decipher all of tbc roughly 30,OOQ to 40,000 g e ~ ~ encoded cs ill the 3 billion ntreleotide base pairs it1 our DNA. In 1991, the the11 director of the prqject, drlci earlier codiscoverer of the DNA ~rzolecrtle,Jarnes Watson, issttecS the follolvix~gstatexrterlt: A rilurc i~nportdnt\et of Inscrucrron books will never be. found by k~unldnbeings. When finally interpreted, tlie gel-tetlc menages encc3ded within our DNA molecules will provide tlie ult~rnateAIlswerr tc:, the cliei~iicaltinder-pinning of Iiurn~ne x \ tence.Tl1ey not only help ~w understdnd Iiow \tie tixnction as Iiertltliy h u m ~ nbeings but will also expldin, &c the chexn~cdllevel, the role of gelietxc Eictorc in a multitude of d~scdscs-such 2s cancer, Alzheintcr5 d~scxscdrrd ~chizophre1iia-tl12t of people," dimltztsh the individtrd fives of so Inany ~r~lllions
C=.lear;ly,deciphering the genetic code is niodvated maitlly by tl~erapeutic concerns, and a better tlnderstanciing of how genes tilncri.on could lead ta better means of preventing, treating, or even curing diseases and pmmoting healtb.Tbis reasoning is based 011 the theory thdt diseases arc caused by iIIutant allcles of gcsies that Fail to properly encode prcjtcin~necessdr)861s tbc rehwlatiori of cell functions, which in turn advcrscly affect the filnctions of differer~torgzlns and orgz~ns)isterz?isin humar~s. Soxrte believe thatW2tsoxl's goni socm tvill be realized.Tl~isis in the wake of the joint allnouncement in Jtme 2000 by C m i g k n t c r of Ceiem Genonlics ax~dFrancis Collins of the Natioi~alHuman Genome Researcl? Xnstitute that they had cunii3leted a first draft of the entire mapped m d sequcnced l t t r m a ~genome, ~ Presumalrly it will be only a matter of time ic can be usecli to predict whctbcr peol3le will likely before g e ~ ~ e t testing develop discase over the course of their lives and tbus serve as a form of discase prcvcntion. C;enetic kriowlcdge could lead ta better diag~iosisof a ~ l dtreattl-te~for diseases people have already Collirls asserts tbdt the
coiaplete i ~ ~ a p p i nand g sequcr~ciligof thc gcliaiae will make pos"l1e ""a new u~~derstanding of g c ~ ~ e tcontributions ic ta human disease and thc dc~*7e1oprllent of rationni swategies for minimizitzg or prevenfing disease pheIlowpes altogcther."~~ This picnrre is rl~isleadilzg,Etowever. 1:)iseases with a geiietic cause may be divided into three types: monogenic, pdygenic, and. multifactorial. The first type is caused by a mllrtation in a single gene (Cystic fibrash, sicMe-ceU anemia, Huntinson's disease). The second is caused by n~utationsin several or mare genes (same cancers). A I I ~tbe third is caused 'by the intcracdon bcm7ccn several or Inore genes and er~viror~mer~tal factors that trigger xncttations in these gei~es (1n~)stcancers, heart disease, mental disorders). In Fact, it wc~uldbe more accurate to collapse polyge~iicarid mtlltihctorial diseases into o i x cdtegory, si~zceFries arid the enviro~xnent.togetlter play a critical causal role iri a11 diseases of the second and thirtl types. Cal-lcers,for exanpie, usually result from multiple genetic mlltations that are triggered by such e n v i m mental insults as radiation or variotrs patltogens, Because these insults rarely occtrr all at once, cancers ~ p i c a l l ydemlop over an extei~dedperiod of time and d c ~not a&ct people until later iiz life. While mai~ydiseases with a genetic componclit are inherited as i~~onogcnic, thcrc illay he variadoils in tbc 111odc of iiiberitancc tbat determine thc risk of getting a disease, as well as the time of onset and its severiv. in parricular, a rl~trtationiri the R R C A I or ESIKCA2 gene gives a wontan who inherits it a lifetirne breast cancer risk of betweeri 50 and 85 as disdnct korrt a 12(%risk for the gei~eralpopulation, where bmast cancer appears ta be multifactarial. Furthermore, a strong hercditnry factor has been ilnplicated in early-onset t3arErrnson's disease, while the later-onset and less severe version of tkrs disease appears to bc multifiactorial. Significantly+ordy a s~aallpr~>porti01106 the population is affected by i~~onogcnic, Mendelian, disorders. This is why clain~st h t ~gc~ietics1vill revoitltionize lrzedicine by foctlang nnrro~vlyon specific geiies are greatIy exaggerate~(.To he sttre, lnappitlg and sequencing the exitire hutrtan gcnolne will fend to the identificdtion of rnore genes i~rzplicntedin various disorders. But n~ostdiseases ar-e catzsed. by more than the actiol~of rnutadons ixz single genes. Neil Holtzman and Theresa Marteau attribute this to ""the incomplete pei~etranceof genot").pesfor common (multifactorial) diseases."'" 1x1 siinplified terms, tbere is rarely a direct causal link bctwecri a given gcnetic mutatic>i~and a given disease. Having tbe mutatioi~does 11ot neccssarily fyncai~that one 1 \ 7 d dcmlop the disease associated wltb it. Eve11 in a farnily with a history of a Ileritable d i s d e r , there rmy be varying degrees 'Xj,
of penctrance, and sct not every rncxnbcr of tbc gaxnily will develop tbc disorder.This tlndcrscores the ambig;~it)rof thc gc~zeticcoxnponc~iti ~disease. i The proportior~of people carr)iitig the mutation who acnrally develop the disease is quite low. IloXtzmr~arid Marteau focus on tlie search firr susceptibility-conferrii~ggenotypes far breast cancer, colon caricer, early-onset disease and point out that in each of these Type 2 cltiabetes, and Alzheii~~er's disarders genotypes account for less then 3% of all cases, They explait1 tl~is by saying that "the risk of disease conferred by alleles at oi-ze loc~tsdepends not only on allelcs at other, i~idependcritfyscgrcgating loci, but also on envirt>i-zrncntalga~tc3rs.'~g t'erhaps the best explanxion for the irzcorxrplere paietrarice of getintypes b r disease is the phenomenon of el~(qc.~lt.sis.AItliough the term itself literally xneans "above" or "over'" genes, epigetiesis is the science of iieritahie cha~lgesixi gene evression that occur witlio~rta chatige in DNA sequence.9 In this process, mtrbtions occur not becattse of changes to the base pairs constituting t l ~ eDNA n~olecule,but because of otl~erchenlical pmcesses. Gene expl-essioi-zcan be modified by chemical groups attstching thelasclvcs tc:, tbe base pairs, ;affecting the functions of thc prc3tcil-z~tbe gencs crzcode arzd in turn thc filnctions of the cells tbese protcixis rehwlate. Methyl groups, composed of orzc carborz and three hydrogen ataxns, prc3duce such an efx-ect througi~the process of tl:rethyladoi~. As t-fojtzmal-land Marteatr firther point out, "tl~ecoll:rpexiq of die genetics of G O X ~ ~ diseases X ~ ~ ~ Xcasts I doubt on whether accrrrate p ~ d i c t i o nwill ever be possible, AIZeles at many dif-ferent gene loci m.211 incl-itase the risk of certain diseases only when they are ix-rherited wit11 alteles at other loci, and only in the presence ot'specific er.rviroi-zmentaland behmiur-al Gctors,""'The upshat is that the gc:,als of better disease p ~ v c ~ z t i aand n trcatmciit w d more likely be rcalizcd, not Izy a narrc:,\\7 &>cuson pardcular genes, but i~zsteadIzy stuciying gencs wir;hi~za brc:,ader causal framework that also i~zcludesbehavioral, clivix-onnlerital,and other biological hctors in addition to gexietics, Still, a satiscactory account of healtll and disease in xxredicine car1 be givell ollly within an even broader evoltrtiotiary biological frdrnework. This is if one accepts Randolph Nesse and George WiUiams's elaborated version of DobzhanskyS dictum: ""Evoltttionarp biolo'q is, of course, the scientific foundation of all biolo'q? and biolo&qis the foundation h r all r~~edicinc.'" l The relations alnorzg evctl~tio~z~ry biolo~y,iaedicilic, and disease can be illustrated by a brief description of the function of tbc ""inatc'" arzd ""a&ptive'kcoxnponc~itsof the burnai-z in~rnunesystcrn.
The innate compax'rent dc~csnot rcqr1ir-c.prior sensitization by a specific &]reign antigen to bccoxne activated. lkather, tbc elements of tbls systcxn (tnacrol?hager;,nantrd killer cells, complerrrerzt, arzd xzaturally occtlrrirzg antibodj~)are actiwted noxzspccif;rcaily by any axztige~~. 111 the adaptiw carllponent, a period of prior sensitiratioxz to a specific antigen is requil-ed be&?reit revonds, Once sensitizdtion occurs, memory cells are geilerated and remain in the circtllatiail and lymphoid tissue &?r life. 13 ceUs and helper and cytotoic 71 ceUs constitute the adaptive compollent of the humail imrllunc systcia. These two coilllTanents and their distinct but related fimctioi'rs barre becri naturailly selected in order to protect our org~nisins6c)m potentially life-tbreatcriixig micrcjbes sct tbat they do not bccoxne pathogenic.?'he xxretnory celfs i n the adaptive artn of- our irn~ntrnesystelrts enhance its ability to tvard off irxlfectiotts agcllts by e~laltlirlgrllilliorzs of xxtolecr~larreceptors to repeatedly rccogr'rize these agc~ztsand guide the body's defenses iri the apltropriate way." Immune memory cells are a n'rajor reason cvhy hunlan orgdnisn'rs call survive despite constarlt threats from microbes, C:rucially, tbcre r ~ ~ ube s t a baZai'rccd response from the inr~dteand acfaptivc arms to S;>rcigrzageiits.They r~~trst be patent c r i ~ u g htc3 protect OUT orgarusrns frcxa virulent r~icrobcs,but not so patent thdt they cause autoin?xxrtrlle disease, wI~icllin extrexrte cases cnrz leacl to the derllise a f our organisrrts.This bdlarzce irz the respoxzse af the two coxllpo~lc~its of the hrrxxraxz inl~xttrxzesystclxr has evolved to protect hrxrllan orgarzisrns konl infectious agents and ther-ehy enhance their survival and 1-epmduaive fitness so that genes can be passed on to iilml-e organisms, r3epnc.I the age of reproduction, however, nattxral selection lias no reason to protect us in this cw~y We becorm xnore susceptible ta chrc)i'ric diseases as we age because our inllntlx're systcrns are I I O ~dcsig~icdto work as cfFectivcly or efgciendy later in life ;is tbey are earlier in life against acute infectious disedses.With the exdrxrpie of the ixnrnune systenr in xxrind, whcs.1 questions of treating or preventimg disease thmuglr gene thempy or other fonns of gexzetic inter~*7cntiot1 arise, they should he placed tvitliin a fi-arxrework of evolutionary bioloCqfas this is the best way to understand haw geiles tirnction in maintaillillg healitli or causing disease, I have been using ""health" and ""dsease'\ery loosely. Because they figure praxnineritly as core terms in this discussion, solac: general dcGnitions arc in order. "Hcalth'5s tbc biological coxiditioll of the brrmai'r body and brain when cclJs, tisstlcs, orpns, and or~;~ax'r systcrns function norillally In contrdst, ""disease" i s the biological concjitiorz of the body and b~dilxlin
which these salnc physiological features dc3 110t fu~ictionnormally, often because of tbc lack or dysfunction of cnqnles or otl~crprcjtci~lscritical to 1:)axliels't; vierv, the regtladoiz of cellular processes," O r to adopt Norx-rta~~ '"disease and disabiliq are seen as departtrres ii-01~1spcies-wpical norrl-tal orgntzisntir,rz or A111ctiotzing."i4 tlanieis tilrther says that ""acading to the nornlal fu~~ctional model, the c e n ~ apurynse l of health cart. is to maintain, restore, or campensate ii-tr the restricted oppam~nityand loss of funct.;on caused by disease and disability;" "" 1 will return to this defi~~titioi~ of disease and the gcxls of inecl.ica1 in chapter 3, when I discuss genctic ei~h~jncemcnt trcatlllent. Some diseases arc both biological and i ~ ~ e n tat a l tbc salnc tiinc. For example, sd~izoptlreniais characterized as a disease of the brain it~vc?lving dj~sf~~rictir,n of netlrdl conr~ecriviva i d the ~~etlmtrdnsmitter doparxline. It likely is caused by a seqt1er:lce of multiple "hits," or insults to cell I:)NA, which include a combinatian of inherited genetic Gctclrs m d nongenetic cdctclrs aKecting the replation and expression of genes controHing brain functi.on.l"n this respect, its etiolog~is sinxilar to t h ~ of t most canccrs.Yctt schizophrenia is clinically cxprcssccl. as a disease of the mind involving cognitive and afi>ctivc abnormalities. So, in this diseasc at least, the biological and thc mental arc il~ttert~7iiicd. Aittlough I am in geiler'11 agreetl-les:lt with 1:)axliels's definitioil, disease lztzrst be distiriguished h l z t ijlness arzci itisabilir?;. ""ll~iess"is defined as the p';ychoiogicnl experietzce of pain or other ~zlailifestationsof nisease. It is associated with sugering in the sense that illness involves one's sul?jective response to discase.17 Thus, wltile tlte health or disease of tlte body or brain is defined in biological terms and refers to a human organism, illness is defined in psychol~gicalterms and rcfcrs to a person's tlnique pbcnoiaenological experience of living with a diseasc. A persoil may 11,zlv.c a diseasc or illness yet not be disalzled by it. "Disabijtity" kiplics a gcncral i1lat3ilit;y to hrnntlate and plrrstie a life plan, where a rnentnl or physical condition presents obstacles to undertalri~lgand colnpleting projects within that plan. In I Z I O S ~cases, people are disilbled by disease; but dise,tse does not necessarily imply dis,abilit)i, If a cvoman ltas become inkrtile as a result of endometriosis but ltas no desire to have cltildren tltrough normal reproductive mealls and can control any pain associated with it, tlten tkrs disease would not c o u ~ as ~ ta disalziliv &>rher. Moreover, hypertcnQon may be cfassifiecl. as a discase in thc sc~isethat it i11vc3lves a dysfu~ictionof tbc m c ~ h ~ ~ ~ ~conisrns trc3liing blood prcss-tzrc within thc body. But if oize is alzle ta control both systolic anci diasrolic pressztrti, mitllin safk lirrzits by tctkitlg aypropriate anti-
hypertensive r~~edication, tbcrz onc could live ~ v i t bthe discase without bccoilUrig disabled by a stroke or cardiovascular disease.. Stzme ~xlightchdknge the definition of disease in terms ofspecies-vpical functioi~ing,ciairning that tlierct is rin objective, vliz~r-freeconceptioi~ of ft~rictionand therefore no o k c t i v e , \palue-free c~nceptionof disease. Apinst the ol?jecti.vist,whose conceptioii of disease is grounded in Gcts about human physioloCq9the constructivist saps that "function" a d '"disease" are social colistracts formed relative tr:, the values of diEerent social groups or cultures. l But constructivism ~nistakcnlyidcritifies thc physiological functic:,iis that the body's organs and systcrns (sardic~vascular,endocrine, inimrznc, nervous, arid so on) natumlly are desig~~ed to do with fiow diFerczrit social gl-oups or cultures assign rneaning to tlte~efunctions in the t v q they affect the qzrafity of people5 lives. What Ixzvst he distiloguishmi, tiie17, are the pl~ysiologicaldysfunctions tl~atcatzse disease, on the one l~and,and social judgments about qualiq of life given these dysfilnutions, on the other. Nuthing in these judgments vitiates the objective phy"01ogical &fillition of disease. Mure iniportarit, though, 1 ~ b c n1vc Justify a ~nedicalintenrcrztioii ta trcat or prevciit a discxse, it is by appeali~igto the way irz which the discase aiFects or wctuld affect people's quality of life. And thcrc arc soiae diseases ericailing so r111l611 pitin and ntffering as to lead to a gerierd consetzsels thnl- tlie Eves of peopje mitli these diseases wotrld not he worth living, Prenatal testing a d selective ter~ni~latiori of early-stage fetuses or ernbryos with genedc anomalies causing these disorders could be justified on grounds of disease i?re\it.ntioii. Interventrian in the f i r m of gene therapy migl~the justified for people who already exist with severe disorders, tbough the risks have to be wcighccl. agailist the patcritial bcneGts, In the light of tbcse points, it is iristr~~ctive to c~lzsiderSanhlippc:, syndrome. This is a genetic discase r~~anifcsting 111 early chldhood and causirig both se%7erti, rnental mtariidtion arld aggressive hehavior. As Philip K.itcher reasoXiS: Testing to see fa Ccrtus bears an allele tlsr Sanfilxppo \yndromc 1s justlficd at botconi
because. the. htcs hvcd by these ch~ldrenw~cl.tthese allelet arc sadly truncated and may d~mrnlshthe. quahty c?rfothers, nor because Sanfilxppo 15 a drrease. c?rrbecmse people In Western roclety tit> not value chtIdren whose pliyslcal, coFlltive, e~llotloilal,and bel i ~ v ~ o rdeveloplllent al 1%~lla%nwlp disrupted. necldlng w h ~ c htypet of prendtaj testing or whlch typet of ~llc>Iecular mterkrentlon are accel.rtable requires ut to ark Iiow the test and tntersrrx~cionrwould af5ect: the yrx,tIif?r ofhtturcr lives,14"
I k c t ~ r ~ i to i ~ e~vg~ > l ~ t f ~ bi010~7, ~ i ~ a r y some authors estimate that up to 80%)of all cancers arc envirol~i~~ental in origilz, suggesting tbat exteri~alinsults to 1 ) N A are the rndir~cause of this and other diseaiies,'"This is plausible explanatiot~as far ns it goes; but it does not go far etlough. For an e%7alrttiox1aryexplar~atiax~ inciicates tbat dicrc is xxtore ta die xxttrltifactorid accurlnt of disease. 011 the multifactorial model, the more carcinogens or other external illstrlts to DNA to which a mranlan is exposed, the higher wlU be her risk of getting breast cancer. This is supported by the Fact that in the United States there is a correlation bet\vcci~thc distribution of tcjxic-waste dump sites and regions of high breast cancer 1nortalit.)8;Presu~nably,the i~icidenccof breast canccr wtjuld be 111uch higher in these reg i o ~ than ~ s in others. 13owever, d study by the National Center for 13ealth Stadstics sl-rolvs that the ir-zcider~ceof breast cancer is jrxst as high in xxtdjur xxtetropoiiean areas, especially in the Northeast, wllerc toxic poflutiot.1levels generally are lower than elsewrhere and where education and socioeco~~ollltc levels of kvomen are higher than in tile rest of the country In contrast, the Southeast has a lokver incidence of breast cancer whde having a higher tecriage preglialzcy rrite and a considerat?ly lower propartion of couege graduates and profcsionals th'311 in thc Nortbe~st.21M of this saggests that a11 crivimnmcntal expiiandtioi~for thc discase neccfs to be supplexxrexlted by an cvt;,ltztioxla~one. Higher educatior:~ancl incolxre levels far xxtany wornen in the Northeast ir-zdicate that ixlcreasi~rlgx~rzxxrbersof liyorllen are either foregoixlg or delaying having c1tildre-e.nuntil afier they have establislted tltemselws in a career. If our bodies are designed by natural selection to enstrre repmductix fitness early in life, then mrhatever cjjsrtrpts this may adversely affect certait~ bodily processes, in this case the action of critical hormol~essuch as cstrogen 011 cells in breast tissueewe do k n c > that ~ cfvldbeari~~g bebre tbc agc of thirty has a positive cB'ct 011 thc actioi~of the rclewnt hormones. Mure vvo~rtcx~ are having fewer babies, dnci arc having therm later in life. This xxteatls r1lol-F: xxrenstrztdi cycles and cor~sequer~tly a greater arnount of estrogexl circtzlatit~gin their bodies, Because of the effect of this horrnone on cells in breast tissue in particular, not having chddrrln before age thirty puts women at an increased risk of developillg breast cancer. An evnlutionarp explanation of the incide~~ce of this disease is supparted by the lokver rate of breast cancer among wcjiaen in tbc Southcast, ~vherethe rate of teenage pregnancy is higher. That is, woxacn's bocliies have been dcsigncd over I ~ ~ I I ' generations )P by natural selection to cribal~ccreprcjducdve fitness and slrccess earlier in life. Behavior that does not accod with that design may
111ake their bodies inore susceptible to certain diseases, and dclqing or & ~ r e g ~ i lrcprc>ducti~n lg call work agail~tstnatural desigri and increase the risk of breast carleer. Cher time, the 1~od-ycar1 ddjt~starid becornc less srrsceptihle to &is disease wheri reproduction does not occur withilt & certair-r age ""1%~". But the period of time ii>r the ddj~~stmer:g to take place would invdve many generations of women. Similar-ly;Nesse and Willrams point out that, cvitlt respect ta the ltunlan diet, tlte availability of certain &?odshas been so I-ecent that natural selection has not yet had a cbal~ccto adjust to thcrn.2VThis phenomena11 h a bad adverse effects on the health of certain populations, For example, Native Alncricans traditioi~allybad "".fast-or-6d11?i11~" dicts depcriding largely 0x1 tile availability of cojrtplex starclles and lean xxreat fmxrr wild gaxnc, Ncnv tbnt foods consisting of satumted fats and refrwd carbohydrates are readily dwilable to thexn, there is a xxruch higher incicier~ceof obesity arlcl the associated diseases of taypertension and diabetes among them as conlpared wit11 the rest of the general population. In evolutionary terms, tlte bodies of people in this particular popillation haw yet to adjust ta these dictav changes. Indeed, in illally respects our bodies and pbysiolahy have not transcended our evoltttionary past but rather are the prcjducts of that past." Still, dxz, evoltzdonary explarlatian carlxlot tell tzs what the carrses of disease are in specific cases. Ir provides only a general tll~derstanciingof die origins and de\7ejoptnent of disease in the hulrran species. 1:)istinct koxn the three types of disease with a getzetic colnpotlerzt are three possibditks for a giwn gcL.navpe,the combination of alleles at a particular gene locus: normal, carrier, and disease.24 In a normal genoqpe, tltcr-tt ar-e at least two ft~nctionirtgcopies or aileles of each gene, which illcans tbat the protcinubc gclies cricode and tbc filnctions the protcil~ts regulate will operate properly With a carrier, there is onc functional and oize defective allcle. By itscff, the dcfcctive ct~pyof the gclie 1vill have no adverse eEects on celfrltar or other piysiologicnl ft11:lctior.ls,Rut if-a carrier xxtates with another carrier ancl their dlleles colxthine, then there is a sigxlificaxlt prol2ahiliry that soxlle of their childretz will illherit the ~rttr~ttion and develop disease. Tltis scenario is tifpical of the mode of i n b e r i ~ i ~ cofe sickle-cell anemia (SCA) and cystic fibrosis (Cl?),which are sizlgle-gene autasomal I-ecessivedisorders. SC:A is a discdse caused by a ~ n t t ~ i t iin o ithe ~ allele coding &>rhemoglobin, the oqge1i-car~)8i1igpr~jteixiixi red blood cells. Tk3 abnori~~al copies of tbc allele (r>i.reh m cach parent) cause the individual's red blood cells to 1~econz,cdeforrnccl, lemdix~gto blockage of bloc->dvessels dirorrghout the
body This rcst~ltl;in acute pair1 and clisability cady in life and often a11 early functioning prcjtcili, C:FTlL (cystic death. CIF; is caused by an ahnori~~ally fibrosis trarisrnclxrt7r;lm coriclrtctallcc regtlator), which reg~ilatcsthe trarisport of cliloride ions across cell xnez~lbraties.'Fhisleads to excesive mucus prodnctio11 in tlie lungs, zx~akitigone vztlr~erablcto opportt~riisticinfectlotis caused by stlch bacteria as I3,ceudot~lcs~rasdcrzd~izlclstr,as well as tlte dysft~nction of digestive enzynles in the pancreas, which greatly impairs the abiliv to & p s t foodTrerztments &?r the synlptoms of CF have impl-aved over the years, but those afflicted with the disease usually dic by the third decade of lik and h ~ v edecreasing quality of life as they age with the disease. In rec~ssivcdiscases, if a child inherits oilly one copy of a defective allele k o ~ none carrier parent, the11 he or she at xxrost: will l->ca carrier and will not actually develop the disorder, 1x1 fact, carryir~gone defective copy of a gene tlint vvotrld otller~,visecause disease if it were irilrerited with a secorid defecri.~copy can pmtect one from other diseases, Perhaps the most 6rniliar &sease firrjillg this description is SCA, wltcre one copy of the sicklecell aUele not oldy does not cause the disease but afso confers pl-atcction against xnalaria.This is prcvalciit among people native to eqiratarial Ahica, where r~~alaria h a been an er~deillicdiscase, Intercsdngly the relation bctwecn SC:A and malaria seclns to coi16rm the evcjlutiondry hypothesis of the causa) inter'lction t.ternt.cn geries and the extertial envirmilrtent regardof disease. The allele pmtect-ing against the IDlmrrzodifrrr1 ing the i~~ciclence resporisihle for n~afariais sdected iirr in an ei~viromntentvvliere this protozoan pxdominates, tltereby enhancing the survival of ltuman orgdnisms in that environnlen t. Mast ix-rherited cancfitians are autosonlal recessive, TXtis nleans that if two carriers have chilcliren together, then each child has a one-in-four ~h~311ce of i ~ i l ~ e r i t i the ~ i g condition and having the symptaras associated n u r ~ ~ bof e r c o ~ ~ d i t i arc. o~~ ofsautosornal domillant inhcriwith it. A sr~~aller tance, which zxlearis that each child of a parent tlrllo carries a trait for a giwri corlditiori wilt have a otie-i~~-two chance of inheriting it,These disorders are rare because the people tlrllo have the111 are often too sick to have children, though people with tlte late-onset Huntinson's disease may already have cltildren before knowing that they have the disorder. With donunant conditions, only one copy of a dekcrive allele necdf to be inhcritcd &or a11 i~idiviclualto have the genctic disease it causes. So, white recessivc genctic conditions arc. Inore freyucrit than doGnant ones in the h u r ~ ~ apopulation, n the probability of a parent passilig 011 a dor~irlanttrait to oEcpriq is greater. Moreover, althotrgb recessive disorders gcner~llyare
inorc severe than doilunai~tones, the latter can be severe as wel, as in Hrxntington's. Eyualy serious arc disotrders tracealzlc, not tt) ally of the t~vex~ty-two drrtosorrzes, but instead to tile sex chrorrzosajrtes, X and V. WeII-kl.~o\vnsex-linked disorcfers are I:>trchenrze ntuscrtlar dystrc3phy and hernophilia, both of which are traceable to xrtutatioxzs on the X chrornosonle and ar-e inherited from the nlotlter by half of tlte male chddren she bears,There ar-e also disorders traceable to chronlosomal al~onlaltestltat are not inheriteif but develop during fetal gestadun, specifically trisomies 13, 18, and 2 3 (DOWIIsyndrc>mc). In chapter 2 , I will discuss tbc prudci~daland xnoral inlportance of the diffcrcnces 111 pr~babiliticsof inheriting dornil~antand recessive traits. I also will consider what the pmhnbility of inheritawe rrzeans for the severity of n disorder; the age of onset of sylnptorns, the quality of life of affected individuals, and the ~7rojectedlife span. In partictllar, I will discuss what our moral obligation is to these individuals if we decide to bring them into existence and whetlter we have an obligation to prevent them from existing at all. In addition, &ere will be more detailed descriptions of tbc biological or 111edical chLjractcristicsof soxne of these i~~onogcnic diseases whcri I examine cases of people whose Iiva arc or wojuld be de61ied in terins of them. I also will address oE~ligatic>i~ and otbcr moral issues with respect to pofygenic or rrzuitifactorial diseases, where the genetic corrlponent is x~otdie oxdy rrzcdically or rrzomlly relevant cor~sideration.
Biologicd and Pdtrsond Identity Thc particular genotypic and phenoty.pic traits tbat phyGically d i s t i ~ ~ ~ q i s h each of us from otbcr hrzman organisms constitute our biological identisy; Rut the biological identity. of a human organism is not equivalent to the psychological idelitity of a person.Tbe rnc~~tal states in virtue ofkvhich we am coizsciortsly aware of otrrsel~*7es as pcrsisring ttlrc3ugh tirrze depend on the contintzed x~orx-rtalf~ix~ctionix~g of ccrtab regioi~sof the brain, These include the cerehd cortex, which coiztmls renrnents wliidi we exist. f3ersonhood and personal identily are psycliologicsl concepts. But the ndntrf: and content of the lrterltal stittes in which personhood ancf p e r s o d identiry consist cazlsally rlepcrid on the brain, body and the social and physical environment. According to the Cl~filrdlitt~lichL>kriot.lavy,a '"efion" i s '% self-conscious or rational being."This is similar to the definition given by Derek 11ar6t, who clain~stbat "to bc a person, a being must be sel6-conscious, a1\7arc of its ider~tivand coi~tinucdexistence over tinic.""" The criteria of being a person, 1\7bicb coiisist of mental states causecl. by ccrtlril~tbrain and bodily hrnctions, are zxlorc contplex than the criteria of being huxnarl, wliidi i m l v e brain and bodily iiltlctiolls but not those llecessary to gene r a e and stistairl ~rtencallife. Tlzis intplies that persons are not identical to hurryan organisn~s,or hurryan being. Athough t l ~ etwo ternls son~etimes are used interchangeably>""person" i s a psychological concept, while ""human being" i s a biological concept. As I w i l ercplain stlortly, there are gcrod rcasolls &>ril~sistil~tg thdt we arc essei~tiallypersons rathcr than human orgarusms. Rcing a person at a tinic is closely related to persisting as oize and the sarne persot1 throtlgh tinte. Persotlllood is a syncliro~ziccotlcept, while persoxlal i d e n t i ~is a diachrc3nic collcept. Follo~ving13nl-(itand others, persoxlal identiq consists in tlie llolding of relations of psycliological connectedness and continuity betmreen and among nrental states over periods of time,"" Because the refations among nlental states and evellts necessardy depei~d on t l ~ ebrain and body, and because no entity such as a soul or (:artesian ego is presuppased as eesting prior to the bolclilzg of tbcse relations, the pasitioll I am adc~ittil~tg rcjects dualism, This tbcary says thdt while there arc correlations bctwecri rncntiil properties and physical properties in the body or brain, these corrclatiox~sarc contillgent mther diaxz, xlecessay, For
d~~dlists, tbe mind dc~esnot deper~dessentially on the brain. The pasitio~lI am adoptiiig alsc:, rcjects xnatcrialisii~,1\7bicb says tbat tbc xnind, and there-
h r e prsorihood, is ~lothingmore than physical processes occurring in the brain. For r~laterialists,rnental states art" not sirnply caused by xierxral pmccsset;; they arc netrral pmcesses.Yet l-tecarzse ~zletztalstates have coiltents deriving from the social and physical e ~ w i m m e i ~and t , becatrse they c m have a qualitative character, they cannot be explained entirely in terms of biocltemical or physical processes in tlte body and brain, So the psychologaccount of persoi~hoodand persoi~alidcntity tbat I enical coi~nected~icss dc~rserejects bath rnatcrialisln and daajtis1n.D The positicri~I take is siniilar ta what Parfit calls the ""KedactiorustVie\\7." 1x1 his wc~rds:""On tbc Reducdonist Vielv, each person's cxistencc just i~~volves the cxistencc of a bmin ailcl body the doling of ccrtairl deeds, the thitlkitlg of certain thoughts, the occurrerlce of ccrtailz cxperiex~ccs,and so on."-3i""rovided tltat we locate them cvitltin a social and physical environment, persoils do not exist apart from the pltysical and nlentd eveilts m d states in terms of which we identify them, If tltis is a form of reductio~lisnl,then we should call it broad psychological rcductiorusm. Acc~)rdjix~g to Partit, psychological conncctcdness c~nsistsin the holdi~tg of particular direct Iiltks bet\vcen i ~ ~ e n tevents, al such as tbe persistence of beliefs and desires, the connection bemeex1 a11 intcl~tioxiancl the later act in which it is carriecl out, ancl betweex1 a11 experierlce and one's rllclxrary of it., Tl~esccoilnectinns can he strc>mger,l~oldingover shorter periods of tin~e,or weaker, holding over longer periods, Psycltological contin-trity is the ancestral relation of psychologicd connectedness, consistillg of averlapping chains of strong connectedness and extendillg over longer periods of time than whdt is iiivo~vcdiii particular Iiltks betxvecn i ~ ~ e n t a l Unlike connectcdncss, c ~ i ~ t i n ~ i t " ) rnot c~~ adnlit s of degrees a r ~ dis a trmsitivc relation. That is, it ernlzodies the trr~thof the s)Pflogisin: If A at T 1 is identical to R at T2, ailcl if R at T 2 is icierltical to C ,zt T3, diex~A at T1 is identical ta C at T3. The idea that the connecdons bet we er^ 1~1e11t;llstates hold only ox7er limited pe"iods of time has sg~ificantimplications for tlte idea of prudential collcern about one's ftitur-e sdf ill a genetically manipuiatcd extended life span. I wiU ex~zlorethese implicatians in chapter 5. For present purpascs, though, I need to defend tbc distinctioi~I have draw11 bctwecn pers o ~ and ~ s h u i ~ ~ aorg~nisins, n as 1\7cU as rny clain~tbat we arc csscntiaBy perSOlIS.
A persoil is a psychological k n d ill the sensc t h ~ itt is definecl. essentially in tcrins of the psychalogical properties associated with rnc~ltallife, A huxrtat.1 being is a bioiogical kind, nn entity consistixzg of an integrated set of hiologi~dstrtlctrrres a i d fr11:lctioils,At a very early stage of de.ireloplcrnt, these strtrctures ancl functions ir-zclrxde the potcndal for and eventual actrxalization of a brain stem arid autononGc nervous sy-sten~to sustait~lteart rate, respiration, and the tilnctions of other organs o f a htiman body32 A functi.oning cerebral cortex and other supporting strirctures are not necesto be a burnail orgai~isin.In its early strtgc, a burnail orsary for soi-r~ethi~~g garusm has the patcritial ta develop these regions ofthe braiii necessary &or i~~eritiil lifc.Yct eveii if this patcntial is ncvcr realized, tbc organisin can continue to exist. Because it possesses only the potential arld not also the capacity for xxrental life, and becatrse tile structures arlcf functions of its cells, tisslles, arid organ systerrrs can be explained e11tireI.j; in biological terms, a ltun~anbeing is a biological arid not a psychological krnc2. ""Capacity" in~yliesthe ability of an entiq tr:, exercise some function at any given time, which is not implied by ""ptential." And althotigh some may use ""kurna1.r organism'"^ refer to a q g c ~ t eembryo, , or early-stage fetus and ""kurna1.r being" to refer ta a full-Aedgcd individudl with a body and (part oil a brain, tbcse can be coi~sicliereddifferent stages i1-r the development of being" and ""hrrr~lai~ orgaz~is~x~" one biological, exltit)r Tl~rrsf use ""Er~x~al~ interchnngenbly Give11 t h a ~ t l l ecapacir;\r iirr consciotrsness nncf other fctn~rsof r~rex~bl life that define p e r x ~ d t o o dai-e generated and sustained by certi~inbiological features of human organisms, persons are closely retattd to their organisms. But tltese two types are ontologically distinct in that the capacity f i r mentill life is something t h ~ only t persoils possess. A being can be burnail without ever barring this capacit')8, in whic1-r case it never 1 \ 7 d be a person, or elsc having permancndy lost this capacity 111 which casc it 110 longcr is a orgdnistx~hut person. Put another VVA)~, n persoil is coilstituted by n htl~x~an is not identical to that 0rgallism.3~ An entity tltat has a functioning brain stenl and certi~infunctionit~ginternal organs, yet lacks a t-irnctioning cerebral cortex and other strircttires supporting mentality, m~ouldbe a human being but not a person. For example? an anencephalic infant ~vouldon most accotints be consikred a b u i ~ ~ abeing n but not a person because it lacks the cerebral cortex neccssary &or consci~usnessand other inental states. Sirrilarly, a11 il~tdiviclualin a persistent vegetative state who has peri-r~anentlylost the capacity fix iIIentality also would be colwidered a hrtrmn being brtt not a person. If we take
ourselves to bc esscritially crititics with the capacity for c~)nsci~usiicss and otbcr forms of inental life, if this cayaciv is definitive of pcrsolzhood, and if being lllrrnan does not entail this capaciq, then it follc~wsthat we are essetztialty persons rather than hutrtnn orpninxm or llzrrnatl beings. ?b furttier support this concItlsiot:~,t will spell out tkvo distjrlct serzses of ""tife" correspo~~ding to persons and l~urrzanorganisms, respectively; The Fact that these two senses are not coextensiw and that one begins before and ends after the other will reinf'orce my claim that persans are ontologically disti~ictE~OIII human org~rusrns.It should be noted, though, that I a111 elaborritilzg this distinction with a view to examirU11g hcnv gclles and different forins of gc~iedcintervention c211 shape or alter the identity of persons, Genetic ider:ltiq is not perso~lalidentity. But the ~rtanipulationof genes at difkwnt stages in the l i k of a human orpninxl or a person car1 affect tlre xzatrxre of and connections betweexz rllelital states nncS over drxre determine .vvhether a given set of mental states is that of one p e r x ~ dis~ r tinct persons.
It will he helpfirf to itltr-oduce some ~netaphysicaltertns to elucicbte the isnres at hand. Netaphysiciatls often erllploy sortal corlcepts to estnblish criteria of ldelztiey for er~tities.Thcsecriteria detcrxrtine tvhat corxxlts as being a diixlg of a certain sort, ns we51 2s what the coiltiilved existence of things of that sort necessarily i~walves.The):cjjsd~lpisltbemeen r,ftdse sort;~lsand su/?statm. sortals.34 A phase sartal designates the sort or kind to w h c h an incfividual belongs tl~roughoi~lya part of its history "Child" i s a pl~asesortcil, sincc although olze 1\7as not a child when onc bcgm to exist, olze later b e c a r ~ ~a echild arld then cedsecl. to bc olze, all tbc v~hileremaining olze and tbc sdlnc individual tbrcjughout the various trarzsfiormations, A suhs~ince sorral, in contrast, designates the sort or kind to whidi an itlclividt~albelotlgp t b m g h o u t its entire existetlee. Subs~incesortals indicate the sort of thing an entity essentially is, the sort of thing it canilot cease to be without ceaung to exist. UeercJing the questioi~of what we essentially art., it is clear that the concern is with substance sortds. The iirrzdamental question is whether the relevant substance sortal is t l ~ cpsycl~ological""person" or tbc biological ""kumarz or~;~anisrn,'hrzd I have bccrl ar~wi~zg t h ~ the t answer is the former. My iaai~~t cfaiin and argument on tbis qrxestion c211 be supparted by analyzing when our psychologicaf and biological liws hegin and elld. For
sin1plicit)r; I 1vill stipulate thdt the life of an entiv is the perirrd of time through which 1\7c can trace and iclientify it. If we arc essentially persons defined in terms of the capacir;\riirr lrzei~bllife, then our fives begin ~rzttcfn later than coi~ceptiox~. Accoding ta the psychological conneetedx~esslcoi~tintlir): account ofperso11"I identiw a person does not exist t ~ ~ i tthe i l co11nectedness of mental states from day to day is strong enough to generate self-consciousness. This suggests that eve11 in early ix-rfclncy there is 1x0 seifl conscious e n t i v present and tl~exforeno person eslsts becatise the requisite psychalogic~lconnections d c ~not yet hold. Solne evcil argwe that one callilot become self-conscious until one is a1\7arc of the sctcial and phyGcal envirt>iii~~ent around one, in which case onc would nc3t bccoxnc a person until at least scverdl years after birth.3"ignif car~tly,sex-conscious~~ess does 1 - 1 0 ~appear all at once but gradrratly, thus implyirlg that a persoil cotnes into existence gradually t l e c m e this is a gradual pmcess, the qttestion of precisefy when a person comes into existence does not have a deteminate answer. Nevertl~eless,we call say that t l ~ erough time at issue" nlust be after the brain has developed the necessary structures and functions to generate and st~pportthe capacity for i~~entality At the earliest, a perso~lbegins to exist in the filial stagc of fetal development, but xnorc plausibly in infi~ricy, At the other erld of psychologic~llife, a perso~lceases to exist wbcrl the regi~71-1~ of the brain pern-~anexltly cerebral cortex a i d other st~pportii-~g cease ta fixi~ction.Vetbecause the fitnctioi~sof tkiese rtlgions zrstrafly dimillish gradually, it1 rnost cases persons cease to exist not all at o w e but gradually The question of preciseb when a person ceases to exist lacks a deternrinatc answer as well. If we are essentiaUy organisms, then sonre would claim that we begin to n genetic i~~aterials frc1111 the genetic fiitber's exist a t synga1ny9~ ~ f i cthe sperm and the genctic xnotherS egg fuse to form a siligle-cell zygotc,We cease to exist 1\7bc11 all filnctions of all parts of the brain, beart rate, ancl rcspiratio11 pertnanei~tlycease. In neither case is there a prcrise time at which a httman organistl-t begins or ceases to exist. Syxlgar~lyi s not a11 event but a process tlint it; not complete until aho~rtt.avei~r).-fottrhours after fertilizat i ~ n . . ~Others " might claim t l ~ a tas hunlan organisms we begin to exist ai-otiild f'ourteen days after syngamy, once the possibility of monozyptic t~vitining112s passed.This involves the zygote dividix-rgfrom cvitl~into fot-nl two qtxalitative icleritical zygr3tcs. Thcsc arc coiitinu~uswith the original zygotc but numerically distinct fro111 the origilial as 1~el1as frr~meach other. So there is no sixigle entity that persists throughout the process that ai~ that begin begins with &rdfizatioxz, If we are essentially l ~ t ~ norgai~isrns
ta cxist at syiigd~xy,thcri wbcrl tbc zygote phase of our org~nismsdivides into ~ c organisms, 3 one of us ceases to exist. But silice there arc now m70 zygotes ancl tltus &VG orpnisnts that exist follotving r~~oriozygotic t'~liii~~ ~ i ~htrlrtari i g , orgi1:anismscannot begin to exist at syngi1lrt)r but at the earliest soxlle fourtee11 days or so later. If I were essentially an organism, then n ~ lik y would haw beLgunwhen 1 cwks a embryo, But this implies that 1 once eisted as an uniliEerentiated clump of some eight or twelve cells, and it is unclear l ~ o wanyone cotrld trace and iclientifi aiaoilg these cells. At the other end of the spectrrxm, if 1 were esseiltially a11 organism, tbcrl I could irreversibly losc my cap'~cIty &or mental life and still coi~tinucta cxist. I wc>uld contiriue to exist with only ~rtinintdactivity of die brain stem rtlgulating heart rate and respimtion.Yet it seems implausible that, if f were in a persiste~itvegetative state wit11 ari irre'17ersiblc loss of Ziighcr-tnrair-2 functiox~,the11 X would conti~l~xe to exist. The biological lik of our organisms may cantinrre afier orrr psychological lii;e has ended. But it is orrr psycltological lives, our lives as persons, cvhicl~we take to be essential to us. For all of the reasons I l~aveadduced, should reject the view tbat \VC arc essentially hu111ai1 organisms, or hrzman beiligs, and maintail1 thdt we arc essentially persons. Again, persons arc constit~ztedby org~nisixsbut arc not iclcritical to them,The life of a person begins later dinn arid er.lds eartier that1 tlie life of a llzrrnari orgdriism, even though we cannot specify an exact tints when it begins or et:ids, ]>et us sttppse tlint a hlrmar~organis~~t begins to exist in tlie for~rtof a zygote around h w t e e n days after conception and that this ~vrUdevelop into m embrvc,, ktus, and eventually a person.Wl_iilean increasing number of c d s followr a certain line of development in multicelluhr organisms like hui~~ans, tbis does not meall tbat a siligle irldivich~dlexists t h r a ~ r g h ~ the ut entire prc>ccss.For duri~lgthis period of tkvelapmcnt, embryc>l.riccells arc. undergoixig a contiriuous process of differentiation into distinct cell, tissuc, arid organ types, I:>iffereritiationimplies that biological pmperties tlr-rdergc) sigr-tificarit qualitative changes frorn the stage of the zygote arld ell-thryo to later kral stages. As elnhryc3logist C. R. Atistill notes, "the whole ernbryc3 does rmt became t l ~ efetus-only a snrall fraction of the enll-tryo is tl~ushvolved, the rest of it contilllljng as the placenta and other a~rxdiarystructtxres,"*3' Morccjvcr, even if the cerebral cortex is prcwi~tin rudinien~iry &or111 in fetuses and has thc potential to gclleratc i~~entality tbis dc~esnot iIIean tbat fetuses becomc (in thc icleritity-prcsemi~igsense of ""bcoiae"") persons. As molecular biologist Lee Sdver pailits out, ""athough the ccrcbrnl cortex-the e'17e11trtalseat of htrxxrari akvareliess and exrtodor~s-112s be-
g i n to grow, the cells withill it arc not capalzle of ft~nctioizil~g as nenrc cells. Thcy arc sin~lzlyprecursors ta lzenrc cells without the ability to seizd or receive: any ilet~roIogicalsigrlals, Further steps of diFere~1tiatio11rl~tlst occ~r"-~%A.ilof this suggests that oil& genowpe is not iderltical with one's phenoqpe, and h a t the capacity far mer1~alit)rwhic11 rllakes us persons is not completely determined by either of these biological types. pei~eti-anceand epigenesic acconnt &>r Earlier, I noted that i~~complete the Gct that most &seases cannot he explained in terms of a direct causal coi.ri.rectioi.r to a particular gcne. A second feature of epigeiiesis is tbat it also accounts for the &ct tbat the iclientities of persoizs cannot be attributed ta the functic>i.rsof gciies alone. Succcssivc stages of difTerciitiation in the course of an org;i:anisrn's de17elopmcnt give rise to new sir-uctures with 11ew properties. Tlze geiletic code in the s;)rgote or embryo only contmis the eqc"~ertilmnge of possible phenoqpic otltco~nesin a huntan orgn~~istx~. It does not determille which particcrlav traits will emerge at the end of the pi-ocess.This is because the genetic code itself cannot accoirnt for the interactiai~sbetmreen tlte p m ~ i u ~ot sf st~ccessivestaps of development: and because the trans1adoi.r ofgenctic patciztial illto a particular phciioqlze dcpenas on tbc ciivirc3nincnt iiz whicl~dcvclopxnent takes place. 39 Since we art. considering dcvelopn~erltkotn sc)rgc>tcto elnbryo to fetus to fiilf-Aedged hu~xral.1org;ir~ism,it is the uterit~eenvimt~mcntthat i s espe~ code b r a cially pertinerlt hem. With regar~lto the brnin, c e r t d l ~genes range of synapses a r ~ d~~etlmtrdnstxritter levels. Rut the particular synapses that form and tlte levels of the netli-otranslllitters meiiiabng bet~veenthe synapses result from the interaction betkveen genes and the uterine environment during fetal development. That fictors in this etlvirc>nment c m adversely affect the pcjtential of gencs coding 61s ccrtain bralitill structures aizd functic>i.rstbat othemvisc wcjuld be realized in a normal way is evident in anciiccphaly and schizophrenia, tbougb of course the lzaturc of the xntlltif'actoriai causes is different in these two conditions. If gerles by thetnselves do not detennine the particular strtrcti~rcl";ar~dfuncrions of our brains and bodies, and if our brains and bodies do not by tl1exrtsel\7es deter~rrixzethe content and phenomenolof;rcal character ofthe mental states that make us persons, then personhoad and personal identiv ai-e inllwnced but not deternGned by genotype and phenotype. t xncrc patcnThe upshot of this account of cell differentiation is t h ~ the tial of one stage of a burna1.r organism to develop into another stage is not enough ta cstat3lish a rc.latic>i.rof identiq bcm7cclz tbcse stagcs.Thus a persoil never tvas a11 exxrbryo or fetus, and exnl-tryos ancl fetuses do not bccoxxre
persons. Ail crnbryo or prcwntieilt fetus is a potential ~CTSOII, not ixi the sense tbat it bccoiaes a person, but only in the sense t h ~ itt has tbc patcntial to develop the biological structures and fitnctio~lsnecessary tn generate the capncit-)r for cn~lsciotrst~ess and other xxrexltal states that define persoxls, Wiileil the lik of a persoil rougl~lybegins wiU be critical to assessing the effects a f genetic manip~~latrion on persollal identity, as well as ta whether and to what extent the recipients af this manipulation can bellefit a r be harnled by it.
H m Genes fnffuenee the fderrtigies o f Persons 1 llave argued diat the gezletic properties of a sirlgle-cell zygote ancl early exnl-tryo arc not idezltical to the biological properties of later clxrbrj~onic ancl fetal, stages of dewloprnent of a hzrtrral-1 orgi~nist-n.For the genoqpe only tJetermines the range of possibilities in wbxclt p11enot)rpic traits are expressed, and the traxldatio~laf genetic potentjal into these traits depends a n the illternal biological envirr>nment in which genes ix-rteract and cell differcntiatioi~occurs, The effigenctic llature of diiTcrcntiatio11 rnealls that new and disdnct biological prcjperties 1vill ernergc frc3111 one stage of dcveloltlne~itto the next, a prcjcess that is not cornpfctcly dcterinilzed in adkPa;112ceby the g e n o ~ p eI. also have argued that neither genoqpic nor phe~ ~ o t y p i cd m t i t o s e q ~ ~ i v a l e to ~ l tpersollnl identity Neither of these biological types diat each of LE p o s e s e d e t e n n " i x w v ~ ~we n am, hx-two nlain reasons tl~atare worth repeating. First, the pl~enamenologicalcharacter of desir~s,beliefs, ix-rtcntians,menlaries, and otl~ernlental states causally de17ends on but callnat be explained con~pletelyby the ways in which genes inAucricc synapses and nertrotrai~sr~ittcrs in the brain. Sccond, the contcllts of our mental stl~tcsarc largely a functic>l~ of tbc social and physical envirmnxnent ili which 1vc exist, and tbcse cai'rnot be explainccl. completely by gct:les or their ~7rodr1ctseither. Nevertbelcss, it is important to artictllate the respects in which gct:les and differerlt forms of gerletic interk7entiotl can i13Nrience personat icie~~tiq. The genotypic polynlarphisnls tl~atresult in our distinctit~ephenotypic traits such as hair and eye color, stature, physiopon~y,and ather i7hysicat features af our bodies play a critical role in our self-consciousnt.ss alvareness. Agdi~i,thc body serves as a g r o u ~ ~rcfercnce d or locus in ~vbichour mental stiitcs gc~leratcdand sustiiixicd by the braili arc unifiecl. over time. bctwecri our desires, belich9 and intcritions and tbcir The body r~~ediatcs contexlts in die external world. So tbcrc cannot be any disclxrbodied xxrerl-
tiil states. C;ivcli that the mental states ill which personbo~dcol~sistsare grc~undcdill thc intcractioi~betw~centhe brain and thc body, the condition of the bocly-whetiler it is diseased or healthy-car1 aEect the contexlts of and coi~i~ectiox~s Iyetrvveex~dlese xx~erltalstates. Insofar as the carlclitiaxl of the body is at lease pardy the result of gene expresGiot~in l7hysical traits, and the condjtion of the body influences the mentality defil-utive of persoi~alidentity, genes can at least indirectly affect personal idenriw To make , biological condition of disease can aRect the point slight-iy d i g e ~ n d ythe ol~e'ssense of self in tbc way one cxperienccs the disease as the psychological conditiol~of ifiness, For cxaiaple, a person with a11 early-onset monogenic disease such as CF or SCA, wllicll inlro1vc cor~siderablepain ancl disabiliky and a relatively short life span, likely would have a different set of desires, beliefs, illtentions, and mernories thnn a person who did not 11aw the same diseasc.Tl~e experience o f pain and &sabiliq would affect the qualitative asp"as o f the memory o f one's exl7eriences of the past, as weU as how Gr into the frtture one's desires and ix-rtentions could extencf. Tltis in turn would affect tlte col~nectionsbcm7ccn tbc person's rnc~ltalstrttes, 1\7bicb 1\7otrld be qtialitativcly different and 1\7otrld be connectccl. &or a shorter period th'311 tbose of a perso~lwbose entil-c. biological and psychological life was Ercc of disease and illx~ess,until just before death, The i~liltlenceof gemtics on ideiltity is most pmtlounced in certain cogxlitive arlcl aEective disoders. In these cases, the very al-tility ta have mental states and the condilions of psycltological connectedness and continuiw are directly sltaped by the genes coding &3r critical proteins regllating brain biocltemistry Fragile X syndron~eand Trisamy 21 (now11 syndrcjiae) are c h r ~ ~ m ~ ) s ~disorders mal adversely aiFecting braill and i~~entiil functic>i~ frc3i11 birth, causing varying dcgrces of n~entiilrctiirhtion and the e,urtstelicc of different persorls from those who wtjuld h ~ v cexisted 1\7ithout these xlomdiies. Perhaps the most vexing multifactorial brdin a r ~ dmental sctlizophrel~ia.What sets this disorder is one that 1 already have rl~entiot~ed, disorder apart fr-otn the tkvo T just cited is that the delusions, hallwine\tiot.ls, and pamoia charncteristlc of it usually do not manifest themselves until late adolescence or early adulthood, This can result in radical cltisconnectedness and discontinui~b e ~ c e nthe n~entalstates and capacities an individual h a befbre and after tbc onset of syinpt0111~Indeed, thc disuity bctween i ~ ~ e n tstiitcs a l can bc so radical that there are eEcctivcly m70 dlf^r?rent persolls before and after the symptolns of the disease appear. These can wax a i d wane over var)llng periods of time. While enviroilrncntat f~ctors
(e.g., tbc presericc ofa virus in thc uterinc envircji~i~~ent during fetal gestation) sees= to play a causal role in the ctiolohy of schizophrenia, allother cause of this disorder are ~xtutalio~ls in seritlml gelles aEect;ng dopalrtine. This and other neurotranslnitters are gene products that regtllate the synnptic corlnectiorls in the brain corltmllillg our cogllitive, wlitiotral, and enlotiol~alcapacities, Hence the genetic conlponent in this disease and its i m p x t on the identities of the people wlto haw it is significant. to di~tin~qislt befiveei~early- and late-onset genetic disIt is in~port;~nt orders with a view to ht3\\7 they bear 011 persorzdl idcntity.Ths will take on special importai~ccwhen considering t l ~ ein~pactof gelie therapy and otbcr forms of gcnetic ilztenrcntioi~on emlzryc~s,fetuses, and persons.. Let 11s assume that a person does not exist ~ ~ n ti~ifa~lcy il or e'~~en early Ghijdhoc->d,when one is conscious of oilcself as an ir-zdividrral with a pardcular body, is aware of the social and physical ezwirontrtent, and lids a minimally unified set of n~entalstates. Once these connections have been fornled a t ~ d are strengthei~edm r time as one lives longer, significant disnrption in the col~nectednessand continuity- of n~entalstates would ltave to occur &?r iclienti~ta be altered. Intuitively, ilz a i~~onogcrzic phyGicdZ disorder like eriefit or harm cannot be separated from the I ~ C G I p1y"caf qtlestiot:~of who is benefited or h;trxned. The two qtlestiozls are ir-zextricablyintcrtwir~ed. If w e use gene dieraw to correct a mutation or add a tlormal copy of a gene to a person's somatic cells, h e n we must exercise caution in the delivery of the gene or genes in question.Ths is because cve stiU lack prclcise knokvledge of Awv difi?rt.nt genes causally interact with each other. Altering one iautant gene 111ay adversely affect other genes ancl. in turn tbe functic>l.rsof critical enzymes and other proteins in cetls. TJn&~rttai.rately, the gencral metbod of delivering gelles into celfs through viral vectors does 1 - 1 0 ~alw;1~11; aEect only tlie targeted genes witl.1 r~-Itrl;ttions but others as we11, wit11 possible untokvarcS effects 0x1 diFerer~tcellrxlar and boclily f~z~~ctiox~s, Furthermore, if we f~enericallyalter gerrl-t cells i n the sperm and eggl then the effects wifl not remain with tlte afiC:ctcd person but will be passed on to krmre people. Because we cannot be sure haw altering one gene mril aEect the other genes and the pi-otcins t;,r mrhich they code in regulating normal bodily functions, and because trni~~ttended and unforeseeable celfular and bodily dysfilnctioils could result that wtjuld be passccli on to future people, we hLjvea1.r ot7ligation ta proceed ~vitf?. ca~tio1.r011 this front. Gel-Ietic ii~forxxratiancan be derived front testixig cclts of iiidividuals (pmitl-iplnntatio~zIVF eaAryos, ktuses, o r persons) who, because of the presence of it~lleritedtraits i n their faurilies, are at risk of carrying a recessive or donGnant allele tltat causes a serious disease. It also can be derived through. genetic scl-eening of children, adalescents, or adults in wider groups or popularions known to haw a significant inciknce of mutatio~~s c a u s i ~ ~diseasc. g These tests are extremely po\veduL tools tbat can predict a person's filture health stattls and lead ta the prcverition of diseases to which people xnay be prcdispascd. This would not come through genetic inter~*7entiot-1 but &rough diet and behaviod xxrodification, given one's g e ~ ~ e t i c profile. The Institute of Medicine Corrtxxrittee on Assessii~gGer~eticRisks has recommended that genetic testing only be aUowed for disorders for which a cure or preventive treatnlent eists, Accordix-rgly, they recamn~enclthat screening is not appmpi-iate &?r detecti.ng carrier status, untreatable childlate-o~.rsetdiscases.47 But surely t c s t i ~ ~ g hood diseases, and ~~i~preventablc should be imde available to yield inli3rination about untreata12le and incurable disorders tbat a carrier or affectccli parent could pass on to a child. Ktlo~vingthat there tvas a risk of this occurring m u l d give a prospective
parent soiae degree of rcsyonsibility for the health of their filture child. This kno~vledgewould enal-rle tbeln to prevcnt such a disorder by inhrinir-zg their reasons and clmice for or agaixlst having the child. frzsofar as tve have an d i g a t i o n to prtlwnt disef:,or to selectively tcrrrunatc thcrn, a11 adult ii~tcndingto becornc a parcnt could be tested &>rcarricr status and, if the test were pasitive, avoid hdving childre~lwith a ~ l ~ t h kc iri ~ w ncarrier. This would be one way of disease prtl\7eiztiot.l without t~-eatxncllt.Thmare also prudexltial reasons fnr testing far tlrltreacable latc-onset diseases as earl): as possible. The informarion c d d allotv a person who w d d be aEected to plan the remainder of his or her life in a more meanin$ul cw~y Another important moral issue is whetlter aU people should have equal access tr:, genetic technologies tr:, pmvent, treat, or cure diseases or, nlore contrcjversially ta enhance norr~zalphysical and xncrltal traits, For illany people, tbe delivery of lleccssary or desired gencs illto soinatic or germ cclls through viral vcctcjrs or phitrrnacogci~~mks (drug tbcrapy tailored to specific getzes) w d d be prnhibitively expensive. 7'11e ~zlolrallyobjectionable corlsequenc-eofthis is that only people W170 c o d d aRc)l-cl this techrlology would be able to wail thcl~zsefwsof it. With respect to disease prevention and health p m o t i o n , it cvould make some people better off than others cvha are not well of3 to begin with &rough no Gult of their own. With respect to genetic enhancen~ent,it wotrld make some people cvho arc already 1\7cll oEc~ac.11 better oK, bath in tcrrns of an absolute baseline of normal hcalth status and colapared with those who arc 1\7cnrsc off than tbey i11 the saim regard. This 1\7ould exacerbate the prol-zlern of social and ecorlor~~ic inequalic): and tvotrd raise deep questions about the sort of society ir-2 which we live and would tvarlt to live. X tvill exnxriirle this issue ~ztoreclosely in chapter 3, 111 chapters 2 and 3, I wiU address a related moral question that arises when we compare the cost of p n e t i c intervention, and the number of people with monogenic diseases who wotrld benefit from it, with less costly prcvcntivc or therapeutic measures that would bcneiit a iauch greater nuxnbcr of peoplc with xntlltifitctorial discases.Which of these m70 groups has thc strc3nger clairrz ta rncdical carc? This is especially sigriificant g i ~ r the l fact that stlcfl sitlgle-gene disorders as C:E SC:A,Tay-Saclzs, and
phenylkctonuria (PKIJ) a&ct only a relatively s11iall umber of pcaplc.4X C>n what moral gmunds car1 we give research and treatment prioriq to the Inore severe diseases of k v e r people over tlie less sewre diseases of Ixtarly more people? If cltrr geilerd aim in r~~cdicine and b i o t e c h n o l o is to prevers disease and pmxni>te healtll in the greccdure.B L Iif~ WC decide to preverit an allelc fro111 expressing in a disease in future peol3le by eradicating it at the germ liiie, t h ~ nthe effects if tbis prc~ced~r~"-herzeficialOT. harraf~~lwotlld he pnssed on to fizture generrations wkhout their cotlsent. E3ecause we lack co~rlpleteknc>\vledgc of the cojrtplex internctio~lsbet~veenancl arnotlg genes atld gene products, it is extrexnely difiicult, if not it:npos.sihie7 to foresee the long-term effects of genetic modification. The sorts of genetic interventions we uncfertake now nlay adversely affect genedc diversity, which consequently might make the bodies of distant firture people less able to adapt to chaizgng enviri~iztnentalconditions. This could xnake tbcln iIIorc vulnteralzle ta pathogens and disease and less able to live out what we 1\7ould consider a nor111a1 life spaiz. In tlie chapters that follolv, 1 will tlot he recommending at1 absolute pmhibition on all fanrts of genetic inteuvefltiot~,as some of them may yield hetzefits b r existitlg people and those tvho tvill exist in the near fixture. Holvever, our lack of adequate kno.;vlecfge of how genes i~lteractamongt themselves, how tltcy influence biochemical processes in the bacly and of cvhether manipulating them will adversely inlpact on genetic dic~ersiityand tbc health and lives of distant futurc people, rcqrxire that we procccd with caudoi~in tbis eizdcavc>r.I=;regc~ryKavka aptly cxprcsscs this scritin~eiztin a way that incorporates the biological, i~~etaphysical, aizd i ~ ~ o rdir~ensirms al I have discussed: ""X four capdciy to ntanipzrlare genes de'17elops so that we determine the idclitiv of our offipritlg in a biological as welt as a socIaI sexlse, this xrtay inflrrexlce-in w;kys that are not bexligg;ll-our ci?jf"l'.ti~jt" ~ 0 1 1 S C ~ O I . I S ~ E P including SS, our collception of who we are and what our place is in the overall scheme of things."4'""
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Qtiestions about whether we car1 or should preveilt early- or late-onset diseases in people who do 11ot yet exist and tliose who already exist presuppose that we have a certain degree of control over the incidence of disease. This raises iirrther questions about responsibillcy and obligdtion. In general, one is causally responsible for a state of aEairs just in case one causes it ta obtain or h a control over thc events that cause it to obtain. C311c: is morally rcsponQblc &or a statc of afgitirs just ill case onc is ca~sdlfy responsible &or it and is capalzlc of con&orming one's bc11,zvior ta social Ilorms c o n c e r ~ ~ i nhow g one ougi~tto act in cerclin circulrzstances. Moral respo~~sihiliv presupposes casual rtlsponsibility, which in turn prt-srrpposes casllid contmI over states of aRairs.1 But to be morally responsible for a state of affiairs, one must have an obligation to cause it to obtain or premnt i t 6 o m obtaining. In this chapter, I mritl. discuss tltc extent of orlr obligation ~ t states of afE~irsidentified with genetically caused cjjseases to p ~ v e i the and our responsibility &or tbcm if w e aUov,7 them to obtain, There are mctitphy"i6A and epistei?lic aspects of causal control and responsibiliv. The first aspect says that a person has causal control over, and thus car1 he responsible for, a stare of affairs if lze is 11otforced to act by externdi factors 2nd is not compelled to act by internal factors such as irresistible impdses. In addition, the state of affairs must be catrsnlly sensitivt. to the person's acti.on in the sense that, if the person had doile othewise, then i t mrauXd not have obtait~ed.Thesecolld aspcct says that a persoil 112s causal control over, and thus can he revonsihle f i r : a smte of aEairs if be is capable of having alzproprilztc belie6 about thc circums.f;lncesin xvbich be acts and the foresceablc col.rseqtlerices of w h ~ he t docs or gads to do.Wgain, r ~ ~ o rrespon"bi1ity al &or a statc of af6itirs presupposes a r ~ ~ o rolzligation al to preven"t or bring it about. Although both rnctaylrysical and epieernic as-
pects of causal contrcd arc ncccssary a11d sufficierit for a person to be res p ~ n k b l efor a state of afgairs, it is tbc epistcrruc aspect of cal~trol,ot4igatiot~,and mspoizsibiti~with which 1 will he concertled here. 1 will arialyze what orrr kx~olvledgeof gci~eticir-zforxrtatiox~arzcl the risk of harxrr it erwails in the h r t n of disease implies about our obtigatIo1^1to pre'17e11t this harm and our responsibility &?rit if we allow it to occur. More specifically9 I %\rillconsider mrhether those who have a genetic mutation with a higb pi-&abdit)i of causing a disease have an ol-rligatioi~to inform other family r~~eml_.rers who also are at risk of dcvclopi~igthat disease. More contrttversially, I will col~siderwhether potential parents hLj\ac.a11 olzkgation to prevent the exiisttcrice of peaplc they call foresec who would experiericc seere pain and sugeriog and whether pareilts can be respoi~"ible if they bring diexrt into existence, Clur kt~~\vIecige of ge~lctici~lii?matir,r~ arid respoi~sibiii~ b r fiovv it is used or acted upoil assume the abhty to test c& of en~bryos,fetuses, and persons for genetic &normalities that predispose them to or directly cause &sease. I waU focus mairiiy on two forms of genetic testing: prc.symptr?n~"atic tcsdng of persons &or mutations cdusi~lgadult-~fiisetdis~rderssuch as HLXII~ingtor~Sdisease and breast cancer; and testing of preiniplai~tl~tic>n embvc~s &or iautatior~scausing early-ol~setdisctrders such as 13uche11i1e iauscular d-ystrophy, Tay-Sachs disease, and 1,esch-Nyhax~syxidro~rtc,as well as for lateonset disorders like E-tuntingon's and Alzhein-ter's diseases."l:'hc first type of testing is done on actual people, while the secur~dtype is done on earlystage huxr~anorganisms that may or may not develop into people. 111 the first insbnce, I wiU argue that individuals who know that they have tlte mutant allele of the UKCA1, I_ZKC_;A2,or Wuntingon's genes, for example, have an ot7ligation to inform their ckildrcii or siblings tltdt they too are at risk of developil~tgthe disease and alfo~cvthem to choose 1%7hetbcr ta bc tested for the presence of the xnrz~itio1.r.1x1 the second instance, I 1vill z p ~ that, e if p21rerlts k ~ i o ~that v there is a high prol2ahilir)r of tmnaxritting a xxrutatlox~that would cause a ~ e \ ~ e disease re in a child and have access to afhrclahle reproductive technoiohy, then diey are o2nligated to have en1I3ryonic or fetal ceiis from which the child would develop tested for the mu&tion. If the ceUs do contat11 the mutation and the disease it causes is severe, the11 the parents have an obligation tr? termillate the further developn~ent of the akkctcd e~nbryc)or early-stcige fctus.This arLwment is motivatccl. by two related r ~ ~ o r principles. al As a rIIatter of nonmaleficencc, 1vc have an obkgation to prcvciit pain and suffering in the people we bring into existexlce, As a matter of justice, we have an obligation not to cause people to
exist with cogiitive, physical, or cinotiolral disorders and disalzilities that wctuld severely limit their opportunities for achieving a ~ninilnallydecent level of lifetirnc well-being. In assessillg the risk of inheriting or passing on a disease wit11 a gelletic carrse, it is not only tire probdltility of the gene causing the disease that matters, hut also the sesierlty of tlte disease and the number of people who may he affected by it,These three factors indicate that the moral obfigation to be tested &?rthe pxsence of a genetic mut;rtiun and to share tltis inhr111atioii with otbcrs is a iaatter of dcgrcc,Whc.n the prolzabiliy tbat a muof tbc disease arc setation 1viU cause a disease is high, whcii the syn~_~ztoms wbeii many people illay bc: affected, the obligation will bc v e r ~ and , stmr.lgcr.Wlzen the probability that a trttttntior:~will cause the disease is low, when the r;yn:lptoms are xxlild to mderate, and when &W people Inay be aBPcted, the o2nligatiotl tvill be weaker. Indeed, there nlay be no obligation in such a case.The particular obligatian to acqnirc. and share genetic inf;l)rnration about diseases is grotrnded in the prillciple that one has 2 n1ol-e. gcr.neral moral d i g a t i o n to prevent harm h m befalling others, provided h'3r111 tct oneself as a result. tbat one dcxs not do more. tbair ~nil~tin~dl First, I exaGnc tbc colitent of obligatiolr and responsibility of what we arc obligated to d c ~and our respoirsibility fix what we do with the inkorxxratioll derived froxr.~genedc testix~gfor early- ancS late-oilset diseases. X then explaitz why we are not obligated to bring any people into cxistel~ce, as well as what our Obligations are to the people we do bring into existence in terms of the moral principles of nonmaleficence and ~ustice,This cvd require adciressing objections that the positlol~for which I am argring TIVOUICIlead to pelfectionism and discrinlinatiol~against people with disabilities. Czonstruing "m7cnrsc off'' "1 terms of the presence or alzselicc of discase and disalziliv, l gc:, on to discuss the egali~irianprinciple holdiitg tbat a si~~aller beriefit to the 1\7orsc off (sick) i~~orally outweighs a grcatcr hetzefit to the better off (llenlthli), I point out thal- hotv we interpret this principle will be serzsitiw to the xlt~mberof people tvho smx~dto benefit or be liarxncd ar~cldie xxragllitrxde of bexzcfit or barxrt. at issrre. Finally, in srrnlnrarizing n1y argrnrents, X reiterate that tltey are nrotivated and supported by the nroral importmce of pi-eventing harm to people.
Ge-netic TesLing, Screening, and Infarmation Gex~etictesting tntrst be disringtisht.d h r n gelletic screening,Tlze first refers to testing individ~~als who are kno~vr?to be at ii~crrasedrisk of hav-
ing a gciietic disorder with a familial mode of inheritance. The secoi~d refers to testing melnlzers of a particular population for a disorder f0r wliidi there may he no faxxrily history or other evidence of its presence. derived froxxr genetic Let us coslslcler soxxre cases involving ix~farxrrddor~ testir~gand genetic screenirlg that illtrstrate the importance of the episternic aspect of obligati~nand responsihilic)r in preventing harm to others. Suppose that a man with a f~nGlyhistory of Huntinson's disease suspects tbat he may have the djsease after developing jerky bodily mweillents. H~~ntington's is caused 'by tbc i~lsertionof multiple i11-Er;liae repeats of the C:A(; codoi~(encoding glutar~i~le) into the IT15 gcne,4 A siligle i ~ ~ u t a t eallele d of the H ~ ~ n d ~ i g t ogcr~c n S is s-tzEcicnt tc:, cause this ultixxratcly fatal disease. It is characterized by irreversible xxlotor and rl-Ielital detcrior~tiona17d cor~siderablcpdin for the patient, as well as considerable nrfferix~gfar both the patiezlt and his fi~~rrily. As a dorni~~ant disor~ler,persoils with Huntinson's can transmit the gene and the disease to half of their offspring. For those who have the gene, &ere is virtual IC)lf%~ penetrance, meaning that they most certainly wiU develop the disease. h&orttanatcly13y the time syinptai~~s appear, tbcy a l ~ x d ymay h ~ v cbad chijtdren and ui11\7ittin$;ty transi-llittcd the gene and tbc disease to them. I-Sc:,wever, tbcrc is now a test tbat can determine 1\7bcther an ilzdivictual has the gene heforc? syn-lptorns appear. Given the predictive power of genetic testing, w d d the rmn in our ewrnple have an obligation to he tested despite the fact that there is 1-10 eEectil~etreatrnexlt for the disease? To the extellt that t l ~ eElan l ~ a dbeen diagnosed with Huntinson's and unkfstood the gene5 degree of penetrancc and the progression of the disease, he would be oMigated to be tested and inform any of his children of tbc rc.sult.Tcsting 1\7ould confirm tbc diag~osisand would clarify tbc 50%) risk for his cbijtBrt.11. Frc:,m the children's g3erspectivc, tbe difference between a 0%)and 2.5 %I risk, or bcm7ce11 a 25%)and 50%)risk, is significant. The difference in risk can iniltler~ceimporta~ltlife choices. The f ~ t h e r wotlld he obligated to he tested and to share the i~~forrmtion because it wotlld pre\rent harm in tkvo respects. First, by having precise inforr~lation about the risk, his childre11 nlay decide not tr:, have childre11 of their own. and t11~rs enstlm that t11e.y- would not t r ~ n s ~ lt il t~ egene and the disease to any additional people. Second, the information would better serve his children's pruderitial interests, er~dblingthem to plan other aspects of thcir livcs accordingly The testing and shdrixig of genetic i~i&orr~~atic:,i~ could xnirUi ~ ~ i zlost e opport~lnitiesancl. maxilnize opportunities f0r achicvclncnt withir~a sliorter life span with severely disabling r1-1idc31eand h a 1 stages.
The point here is to offer tbosc at risk of a severe disease the opportunity. ta make informecl. ch~ices,given how they assess the risk of having the gene and tlie fact that its virtrral IOOX pe1:letmnce trteans that they would delrelop the disease if they had the gene. frzforxrtir-zg a son that he had a 50%~risk of liavil-zg Extrrx~tix-zgton's,which could begin affecti.ng ltim in the prime middle seAge of his life, could allow him to choose to be tested, and dep"nding on the result, enable him to $an the r4maincJc.r of his life in brs hest interests. For example, knowing tbat he had the gene and would have tbc disease, he 11Gght give up plans &or a career in xncdici~ic,which has a l o i ~ gperiod of apprendccshiy, and opt instead &or a career that wctuld crialzle him to have ancl rcalizc oppartunities for achie\7exrrerlt earlier in life, Not being tested ir-2 die face of evidence of the disease in his Falrtity m y be impruderlt for ntch a person F~lilingto plan one's life give11 the kmwledge that m e will have a severe disease in mid~fleage may entiiil &?regone opportunities earlier in lik and &?reclosed opprtnnities tater in life. I3ut inst?f.d~-as prudential considerations alone are at stake, a single inltividual wlto believes or knows that he is at a sig~zifificdntrisk of cantractir_iga genetic disease would not bc 111oralfy obkgatccl. to undergr:, gcnctic tcsti~ig,Tbcrcwould be no othcrs to whom he 11Gght bc obligated. To be sure, die obligatioxl to infar111 siblirlgs or children that axle has a trtosiogcxlic disease rmy be mil.igated by the potential far psychological harm to oneself. Tllis could be it1 the far111 of exrtotioxis such as a~~xlie"~): guilt, shame, fear of blame ti-om fimily menlbers, or k a r of cjjscrimination by prospective. insurers or employers. Still, this psychological barn1 to oneself would have to be mreiglted against the mag~ittldeof the potential barn1 in not i~i&ori~Gng others of their risk. If the ~iumberof people who illay be affected is sigiiificai~t,then the potential for physical arid psychological harm ta othcrs who remail1 igioraiit xndy outweigh the potential &or psychofogical harm to the individrrdl deciding whether to be tested arid to share the information with thezrt. In the case of I--luntirzgoxi's in a parerit with Irtany childwn, there would be trtoral grczritlcls far saying that an itldividual with symptoms and a diagnosis would be obligated to prevent the greater harm by being tested and informing others of his disease and of the Edct that they too may be at high risk of developing it, C:oi.rsider now a case ilfustratil-zg the JustiGcation for preconception gcnetic screening withixi ccrtair_ic ~ m ~ ~ l u n i dThcre e s , is a much higl-rer incidencc of T:iy-Sachs disease 1\7ithin the Ashkcliazi Jewish coia1ntl1iif;)8liviiig in differerlt cou~itries.Individuals affected by this disease ustldfly appear
qrxitc normal at birth. But in the first year of life their ncrvc3rxs systcrns dcgeizeratc, and they trstaLdlydie by the time tl-rey rcach thrcc or four. recessive disorder, tvllere the affected child inTay-Sachs is aiz autoso~~tal herits one Ixrtttant alele from each parent, both of whom arc, only carriers of the trait and do izot hdve the disease. Becarrse of screcnitlg progmlxrs, there ltas been a significant reductioi~in the inciclence ofTay-liachs,This is due to carriers avoiding marriage in Orthodox je\vislt comn~unities,to carrier co~iplesundergoing pxnatal testing and terminating aEected embryos or fetuses, to the use of doi~orgametes, and to adoption. Aclic3lesccx1ts coi~sdtutca large pcrcen~igeof thosc scrceried, which h a prudential and 111oral irnplicatioi~s.13oing sct at an early age allows tbcxn aiaple tinie to plan their f t ~ t t ~marriages re and fa~xtilylives in accord tvith their valtres arzcl to pre'17e1ztthe l~ar~xt tllat would result front having a child with Tay-Sachs disease. One cancer11 with genetic screening programs is that they cause uncfue anxiew and thus can harm those who participate in t h e m LJut the follovving account of a pilot st~idyof carrier screening for C F tltrough a Mood test aiaoi.rg ,5111 sccolidary school studcx~tsin Montreal shovvs that a l ~ x i c q d c ~ IsI O ~always result from scrccriing. St--udcntsover fifteen years of agc 1 ~ c r eii-rvited ta attend ail information sessioll that covered basic geilcttic irifizrrnatioiz &out cystic fibrosis, a d the irxrplicadoizs of beixzg a carrier. A tveck later, die studelits were i ~ l v i t ~tod participate iri the screenitlg pmgsarn. Three of the izitze carriers iderztified had experienced same anxiety on receiving the positive result and one person had great anxiety;This anxiety had dissipated in ali the participants by the time of the folokv-up interview." The most c ~ i ~ ~ l ~ e fcase i i ~ zfor g g c ~ ~ e t scrccriixig ic is &or treatable disorders. What coxncs to illlizd xnost readily is the autasoi-r~alrecessive disorder VKU, ~vbichcoi~sistsin the body's inability to xnetabolizc phe~iylalaninc, arz alxrino aci~S,~ x ~ ctvlllch S can lead to severe rlzclital rctardntioxz ixz agected childrel.1. This can he avoided by a diet I c ~ vin phenyialarzine. Neoizatal screetzing provides p a n t s of affected childrerz wit11 the knowledge they need to allftlu~listerthe appropriate &et and is tlttls a relatively straightforcwkd method of prevei~tingdisahdity and harn~, Considerations of harm also apply to testillg for mutations in the RKC:A1 and BKC:A2 gcncs, which eritail a sig~iificai~tly high risk of l~reast (LIPto 8.5 %I) and o ~ i r i a n(up to 60 ($4)) cancer over a lifetinic. As a dc~minant disorder, children of people with thesc mutations h ~ v ca 50%)chal~cc of dso carx-yiiig the ~xrtttatioizs.Suppose that a wormn in her forties whose
r ~ ~ o t b and c r gral~dnlotbcrboth died frc~mbreast cancer at a relatively early agc suspects that sl-ie h a the x n t l ~ i t i ~Ifn ,she has no sisters or childreli, then she tvouJd have no obligati011 ta he tested and c o r ~ f i wlletlier r ~ ~ ~ ir-2 fact she has it, Tl~erewould not be any corlcern about hanrr ta others, The only concern would be a prtrdcntial one pertailling ta tier C ~ ~ V Iintef-rsts, I mcl whether being tested anif having the knokvledge of whether she did or did not have the mutation served tltese interests.This might include more frequent mamnlography starting at an earlier age. Hokvetier, if she has been diagnosed with hrcast cancer and has sisters or Aughtcrs, then she would be oblig~tcdto be tcstccl. to coi.r6rm t h ~itt is causecl. 1zy the BITheright to she lids tlie xxnttatiot:~ choose whether or not ta zrldergo gelletic testing, which tier dazrgltftif-5 wauld have on being told by her that they are at risk, is samething that she sltould ltave as \velf.Why should she waive her rigbt not tr:, be tested just sa that others might have this right to cltoose? This seems u11Gir to her. Neverthclcss, most rights are not absolute but prin~aFacic, in the sense t h ~ t tbey can be c:,vcrriclden by other considerations, C3ne of these considerations is the prolzabiliy of harm to others in exercising a right.When others xxtay be agected, their collecrive right not to experie~lceavoidable pliysical
aszd psychological harm may c~verridethe particular right of the wt3snan not to expericiice any psycltalogical harm in kszo\vi~igthdt she has the xxrutntioxl. Clrdindrily, xxroral obligations to fatrtily metl7bers are gerierdtcd not by genetics hut itltimac-):the etnotionai bonds one develops i i ~virtue of sliaring needs and interests with otl~ers."~n the case of living-organ donation &:,r tl-anspiantation,f i r instance, one may haw a greater moral obligation to donate bone niarrokv tr:, a sibling, parent, or child with leukenlia tl~ana stranger because of the special rclaltioszship b c ~ c c s them. i T h s ot4igation it~ustbc wcighccl. agai~zstthe degrcc of risk i~ivolvcd,which is why there wctuld be less of an ot4igation to dc~szdtea k;iJ~ieyor part of a liver than holx xnarrc>w.But them is an ixnportnnt disanaiohy betbliecn living-c>rgdn donation and gelletic testing b r breast cancer. 111 the first case, &em is an digatin11 to aid s o t n e o ~ ~who e has the syntptorxrs of a life-threatefling condition. In the secoild case, tl~ereis an obligation tr:, get information about a condition for which one is presyn~ytamaticaild whicl~is more treatable. Marclover, the risk of harm in living-organ donat-ion is mare significant tbaii the risk ill gcnetic tcsd~igbecause it is bath phyGicdZ and psychological, notjrxst psycholagical. 1x1 thc type of breast cancer at issue, it is not intinlacy but geiietics, and the it~oralobligati011 to prevent avc3ictalzle harm, which grc>u~id the obligation to be tested atllf intifri~rone's Gllifd~il of the result. With die inforxlldtioxl that their nlother5 breast carlcer was catzsed by the mutatioil in the BRCA gene, &ugliters cotrld choose w11etl1e.r or not to be tested on both nlaral and prudential grounds. A daughter w11o is contemplating bavitig a child might choose to be tested, in kv11icl-r case a positive result might cause her to change her rcyrodactivc plaszmo the it~oralgrou~idthat she should prevent paksitiaii harm to a potential datzghtcr by transmittiizg the xnutatiori and p e h a p u t h e disease tc:, her. This daugbitcr also might dter her life or career plans on pru&ntinf gmtrl~ds, dt-pe~~ding on whether die undergoes genetic testing and llow she assesses the infor~rrar-ionabotrt her risk of fidvir~gbreast carleer. She mi@t opt jirr a pmphylactic nlastectonly and oopherectomy to eliniinate or reduce the risk and avoid Itwing the disease,Wll of this would binge on her assessment of the 5(k)35%)prohabiliq of devejoping the disease giwn the genetic mutatiosz, a prc3t3abiht)r high enough ta ot7ligatc her xnother to in61s-1x1 her of this risk. Idcailly; a 1~7cnit1ai.rwith thc UlkC:AI or UlkC:A2 it~utatioszcould avail herself of gerle therapy to correct die nlutadon ar~clthereby elirxrix~ateher
risk of breast cancer without surgcry. But as I will explaili in illore d c t d in chapter 3, genc theral~ystill is not feasible &or treating most gcnetic disi ~ ~ g children, dien she could take fertiliw eases. If she is c o ~ ~ s i d e r having drugs to irzd~rces~1percjt7zllationarid thereby produce ~xldtiplee g p that c o d d be fertilized by a mar~'ssperlrl in vitm to form multiple etl7bryos. These e m b r p s could be tested for the presence of t-he mutatinn, afier which a genedcafly nornlal embryo could be sdected for implantation in the utcrtrs and development into a birth, If it were difficult to determine whctbcr the ernbryc:,~had or lacked the mutation, or if the mode of inhcritancc were such tbat all female embrycjs contained the xnrz~itioi~, then she could select only malc embryc~sfor in1plantatioi.r. (While males can dct7ejnp breuchcnne lrtuscrrfar dystrophy (DMI3) and hernnphiria, which 01ily dffect: rl~dles,yTl~e ratinnale far selectiol.1 in afl of these cases would he to preritt~itdisease in arid ellemfore tian11 to people. If a person knew that she had a genetic mutation and a high risk of having a genetic disease, but the synlytams associated wit11 t l ~ cdisease were only mild to moderate, then she would Itme a weaker ohligcltion to inform othcr fiimiIy i ~ ~ e l a b e of r s the risk. For the likelihood of harm to them wctuld bc relatively low. Ixzdeed, soiae might insist tbat in such cases the person ~vcnuldhave a11 obligatic?i~rtot ta infi3rm otl-iers, o~vingto the un11ecessa~psychojngical harm that anxiey and otlier en-totiot~slrzifflltnccasiaxi ixi thexrt.The sarllc could be said about diseases with a genetic cornpoxient that a&ct people near the end of & norrnal life span, such as the more c o n ~ m o &?rm i ~ of A4zheirr1e.r'~disease, But in the small class of cases of eady-onset Alzl~cimer's,as we11 as early-onset t3arkitlson's, bath of which have a s m n g genetic c o m p ~ n e n tthere , cvonfd be compefikg Rasons for individ~zdlsa t high risk to be tested and to ili&ormfii~ndyxnelabers of their genctic statusel"This is because of the s e v c r i ~of tbc symptoms of the disease and tbc period of tinle bctwecri the onsct of symptoms and death, factors that can have d sig11iJiCallt impact 0x1 the lives of those who have
tbc disease and on Family melnbers or others who care for them. Knowilzg in adva1.r~~ tbat onc's cogiitivc and physical c01iditi01.r will begin to detcriorate rftiatively early in life can aloxv a person and others caring h r him to plan fizr the time when he and they will be trtost advrrsely a&cted by the disease.The rrlornl and prudentid rcasoxzs for being tested and sharinff genetic inhi-mation in cases of earlier-onset AlzlteimerS and Parkinson's parallel the reasons for doing the same in cases of Htrntingtons disease. There is also a legal aspect to the oMigation tr:, obtain a l ~ dact on genetic inhorr~~atioii irzdicating a significax~tprobability of transmitti~iga genetic disease ta a chi1d.T~)the cxtelit that embryor~iccells can bc testcd h?r gcnetic ~nrz~itions tbat cause severe disease and clisabiliy, parclits who had afhrdnhle access to tile technolom worrld have an obligation to test IVF p r e i r r ~ ~ a r z ternhryos ti pmduced from their egg and sperrrl if they lcizew that they tvere carriers of a gcrietic xxttrtation. Chz the basis of the ixzforxrration deriwd from the testing, parents could decide tr:, termillate an enlbryo with the mutation or allow it to implant and develop into a perso11,Yct if they decided to allow it to develop with the knokvledge that there was a high probalzility of it causilzg a semrc disease, tbcri tbcy wtjuld be rcsponsible f i r tbcir child5 c~r.rditi~x.r. A child causecl. to exist in such a conclition could file a tort of hvrondul life ;against his parents, or against a11 otlstctriciarz or gerietic counsdor for 1xtisinforxrtir7ghis parents about the risk. If the child was 11ot mature ez~ougb~ or tvas cognirively or fiysicaiiy trr~abie to do so, then an adult could iile a t a r m n the chiid't; bellalf.The justification for the tart \vould be that the parent, obstetrician, or genetic caunselor was legaUy responsilsle f i r the cfiilti's c o ~ ~ d i t i and o i ~ accordingly owe i o iacting ~ negligently or reclilessly in ignoring the risk, it c o n ~ p e ~ ~ s a tfor give11 tbe parents' cxrrier status and tbc pr~>lzhbityof gc~ietictransmission. Suppose that a boy has DMD, a recessivt.: sex-linkd disorder tmceable to arz X-chrolrtosoxxre xxtutatioxz that adversely affects die fr~llctioxzof the dystmphin p~-oten.fr-falf of all boys who are born ta worrlen tvith the mtltadon are affected.Tl.te defect carrses xxtuscles ta begin weakening around age three and subsequent respiratory failure, giving the males aaicted wit11 t l ~ e disease an awrage life expectancy of sixteen to tkvenv years. If the boy's nlothcr h e \ v that s l ~ ewas a carrier of t l ~ enlutatial~and that there \w~sa 50%)chance of transinitting it to a 111ale child, 1 ~ a sable to test ei11bryc3nic cells in vitrc~or fetal cells in utcrcj tbrcjugh a~~~iiiocentcsis, and still allc>wcd tbc embryo and fetus to develop into the child, the11 the son could claim that his rrlntht7r (or both pare1.16) acted in reckless disreg;l;rcf of his welfirr.
Hc could claini that she, or they, h'jrr~~ed bin1 and o ~ v ehini cornpenation &or causi~ighini to exist ill a c~)nditionthat defeats his intcrcst ill h'jvi~iga life that is not so se'17erely restrictecl by the disease." The cchilcl has ta live with a sl_tbst;lr~dal btxrcjerl that was irxrposed 0x1, not coilserzted to by him, His prerlts worlld be morally and legally respoizsible far his corlditiotl on the ground that they knew, or were reasonaMy expected tr:, have known, that there was a significant risk of havitlg a child with a conciitio~~ that cvould harm 11in1, Alternativejy, his parents ~ U g b have t pr-ocluced multiple IVF embrycjs and selectccl. aZL female or oi~lyEe111ale n~rlcarrierernbrps &or iniplantation and filrther development. This wcjuld be a xnoralfy justifiable exalnple of sex-selectior~as a xneth~dof prcveiiting Bgnificant harm to the people we bring into existe~lce,give11 that I)M3 is a sex-linked diso d e r agecting only xnales. Stzme mi@t claim that parents have an obligation to ensure that their children haw the best opporttlnities in Life f i r achiexment and well-being. Suppose that, in addit_ion to t l ~ esex of the eml-tryos, the likely sex~ral orientation of embryos could be ascertaitled eitl~erin vitro or in utero, Bea f . have becri harmccl. 'by discriniination, cause wcjlaen and h ~ m ~ s c x ~iaales it wctuld seem that parents have an obligation to prcvcrlt h'jrming thcir children by selectilzg only heterc>sexttal i~~ates. B~ztit is doubtfiltl tbat any burdens resrrltixlg froxxr being fernale or a hoxxrosexrtal xxrale would be srrbstantial erlotlgti to say that parents hart11 these individuals by bringing the111 into existexlcc. Moreowr, f have characterized disease and disdblliq as conditions that harm the people we procreate, a l ~ dneither sex nor sexual orientadon is a diisease or disability Msa, parents have an obliigdtion only to ensur-c.that their chddr-en Itave aLJeqtlate opportunities f i r achieveiIIent, not tbc best passible opportt~nitics.13:~rciitalobligation to cfvldrcli is grc~undcdill n ~ i ~ i ~ ~ a l e f i c cand n c cbcl?e&ccncc, not perfectionism, Heiicc, while it 111q be pcrmis"iJe fix parclits ta select tbc sex or sexual oricntation of their child, they wotlld not be required to do so. Ail of the ge1:letic diseases I have disc~~ssecf thtls fir ix~volvea colnhina-tion of a high risk of trdnsrnissiot.~from parrnt(s) to oEspring arlcf a high Momover, all of tl~esediseases risk of nlorl-tidity and premattxre n~artality* are montlgenic disorders caused by a mutation in a single gene coding &:,r some crtrcial pmtein reg~latingceH firnctiol~.One multifiactorid disease that complicates thc issue of parcrltal obligation is scbizophreriia. Like bil3olar disorder and 111ajoz dcpressirr~~, scfvzaphrenia tenas to run in faxilies. 13areiits with this xncntal disorder h ~ v cabout a Ifl% chancc of transxxrittixig it to tl~circhilcfrex~.As already x-roted, this disease is caused by
111tztatio11s 111 sevcral genes adversely affectiiig the neurr;ltransi~~itwr dc~paminc.The mutations rnay result h m intcractic.>iisbcm7cen gclies and e\Tents in the zzterilze enviroilment dtlrir~ggesmtion, or e\Tcnts in physical and sociai et:1\7irc,natetzts nfier binh. Sympmt-ns ttstrntly aypear in adolescence or early adtilthood. Scliizophrenia is treatdble, but it requires c017siderable pl~arnlacologicalix-rtcrvention and social strpport to keep it under control. If social support is inadequate or absent, then the disease may become more severe and result in more suffering or even death jtltrowh stlicide) fix the person aaicted ~ v i t bit. C:oi.rsider a forty-year-(lrlC3. si~igk1\7oma11 who carties the xntl~rtionsand has no extclided gainily If she is ct>gnitivelyable ta know that thcrc is a risk of tranmitting the nlutations itnplicated in schizophrenia to her child, ancl diat die reqtlisite social support: w d d be lackitlg, then there may be a reasot.1 far not l~avingntcli n cliiid. If tlie parent. hacl this kno~vledgebut decided to l~avea cl~ildw l ~ odeveloped the condition, then arpably she would be responsible for- that condition. Even so, the Fact that socid and biolodcal flrlctc:,rs beyond the parent's control play a crucial mle in the etjolojg~of schizophrenia, and tbat tbc risk of transi-lutti~igthe disorder to children is orily about 1 0 ($4,wc~uldconstit~zteGtigating conditions, 111aking tbe parelit I have described at xnost only partly responsible for her chiidS disease. tilllike the p r e \ ~ i o u x s akix':"iix& liem the rdtiot.lnl,e f i r not l~avi~lg a cliild w o d d be tied not ordy t.o genetics but also CO other bioiogicaf mcl social factors tbnt could af5ec.t the se\Tcriq of the disease and be harnlful tr:, t l ~ eperson who has it.This example also dustrates that it is ~ matters in assessnot only the risk of tmsmitting a genetic m u t a t i o ~that ing parent" rreponGibili~for conditions that aEect their children, but also tbc xnag~iitudeof the harm their childre11 111q have to experience. A ~ i d tbis rnay bc due ta nongenctic as 1\7cU as to gcnetic Fdctars. Thrzs Ear, I have been disc~ssi~ig how our hc3\\7Ledge of the risk of translztitting genetic ~rtutatiot~s to ofipring and of die likely l~arrnthis rick er1tails bears 0x1 our obiigriltiot.1 to prevent harm. 1 also finve been discnlssir~g our respoxlsihilil.y for the bnrxn these ~ztttt;ltiot.~s catise if we bring people into eistence cvho wotrld have them, But mare needs to be said about the philosophical basis of harm.
Moral Asymmetry and Harm The pinciples of ~rar.lrnalefice~zce nnd jttstice ground the ii>llowit~gnsyt-nIztetr)i thesis,We do not fiave a n l o d obligation to bring people into exis-
tcnce with good lives. But we d c ~have a11 olzkgation to prevent the existence of people \vho wtjuld experience sct rnuclt. pail1 and suB%rir_lgthxt their lives would 1 - 1 0 ~be tvorth living far thclxt on the whole.IV7'hs thesis rests on two adctilionni moral pri~~ciples nncf the ontological disti~lctio~~ betkveeJ.1 humall orgd~~ist:ns (as er1113ryos a r d es~rly-sage,prese~ltient,fetuses) and persons, The person-agecting principle says that a person is benefited or harmed when her interests in what happens to her are satisfied or dekated. l 4 C3nce a perso11 exists. shc has an interest in not experiencing pi11 and staiFcril~g aizd c m be harit.~edif sbc experic~iccsthese over the course of bcr lifctinle. Thc in~lzersonalcoi~~lzarativc prii~tcil3lesays tbat, otl~erthing bci~zgequal, it is worse to c a s e n person to exist if it would be l7ossible to c a s e n different, better-oR, person to exist i t ~ s t e a d .i ~t i~1vc)lvesn cornpnrisot~,not bettvee~zthe existe~zcear~cfnonexistence of one person, brit rddier bet~veentwo &stinct lives of two distinct people. C)n the impersonal. cornparatit~eprit~cliple,we evaluate two potential lives of t ~ v opotential people who do not yet exist, while 011 the person-aft"ecti= principle w e ev~luate tbc life of one persoil 1\7bo already exists.Yet we can appeal to bath principles to support the clain~tbat we arc morally obligated to prcveiit thc existcnce of people who would have lives that on balance wtjuld not bc worth living. We prcverlt liar~nto the i~ldividualswe cause to exist by satisf'yitlg their itltel-rst in not having to experience se'~~erf: pain and szrEeri~lg,nrzcf we avc)icS addix~gto the total alxrount of stiffet-it~gin the vvodd."This issstlmes that the diseases causing the pain and suffering that make lik not worth living callnot be treated adequately 111 chapter 1 , X isrkmed that "pcrson" i s is psychological concept and that ""kurna1.r organism'band ""bi~~aiz bei~lg'>rc biological coizcepts.Thesc psychological and biological coi~ccptsarc oiztologicaUy distinct because they i~ivolvedistiizct esseiztial prcjperties. I also arjgwcd thxt a11 ernlzryc:, or prcsetztierlt fetus is n potential person, not in the sense that it hecotrtet; a person, hut only in the sense that it has the potelztial to develop tlie biological strtrctrtres and f~z~zctions necessary to gcrlerate ancf sristai~~ coizsciorrs~zess and other forms of mental life definiti.ve of personhoad m d personal idelltity through time, It is in1port:rnt to bear these points in mind tbr the discussion in the remainder of this chqter. C311 the plausible asstainlttions that only bcilzgs with ilztcrests can bc harmed 'by tbc defeat of these irztcrcsts, thxt havilzg intcrcsts prcstlpposcs senticrice or tbe car)'~ciqfor rnc~ztalityand tbat only persons and late-stage ~ d nonhutrtan arlimals) l l m this c a p a c i ~it is nora ally perfetuses ( a ~ sorne
i~issihlcto terinillate a hu111an organism at an early stagc of dcvelopiaent. The teri-r.lination affects no one who has interests. A pens011 xnay be harmed by the later effects of pxexzs' behariior during earlier fetal, gestation, as in fetal alcollol syrlc5rotne. Rut it is the person wiio would be harmed by the defeat of his i~fierestc,not the cady-stage fetus. One rnight abject titat having interests does not prestrppose sentiel~ce.For exanlyle, it can be said that firture people, mrha do not yet exist and therefore a]-e not t not lking in a p l l u t e d environment. But the sentient, have an i n t e ~ s in core conc child into esstencc but a diiTcrciit or no child illstead, tbcy brought aborrt a worse state of affairs, fr1 addition, they harm the child by defeatix~g his interest in not having to experie~lcepail2 a r ~ dszlf-Terillg a ~ c ehe exists. The intpersondi, cotnpar~tivepritlciple explains the wrc,nC$t~lnessof the act of bringing the child into existence, and the person-agccting prlnciyle exylains the harmtillness of the act, We need both principles to explain and justify what parents are obligated to do anif what they are respoi~sihle&?r in causing people to exist. I)avid Heycl maintains that the interests of future, potential, persons cannot xneanin@i~flybe refcr~iicedt~ tbc choices and acdoi~st h ~ bril~tg t tbcin into existerlce." This seems to be s~lpportedby my arprment that potell-
tial perxms "3 not bec0111e actual persons, in thc sense of being idel~tical ta them,Yet assulning tbat any person 1\7ho exists has an interest ili avoiding pain a ~ l dsuf-Terillg,and that parents can foresee that a gezletic ~ntltntion in tested ezmbryotiic or &tal cells eritails a high pmbal.ciliv of a condition with pain atid stzf-Teritig,tlie interests of the child can be referericecf to the parents' choice and action. In clioosing tr:, bring a cliild ix-rtr:,existence, tlie parents reasonably can be expected to have some underst;rnd.ing of the interests the child wotrld have once he exists. Granted, tliere is n a lreladon of iclienti~bebvecn tbc embryo or early-strtgc fett~sand the child. Ncvcrtbclcss, there is erlough of 2 causal threxd running through the biological process of development h m earlier to later stages to link thc future interests of ctiildrer~not to fiave severe disease with the past reprt>tluctive choices of parents that resrllced in the exstence of these childzn, !%rental obligatiail mcf responsjhijit)" transfer fro111 their earlier reproductive choices to the later pliysical and psychological conditions of their cliildren cvho exist because of tliese choices. 111sonle genetically caused diseases, sexre cognitive and pliysical syll~ptaim may make people's Iives so painful and restrictive tbat they arc. not wctrth living for tbem, By defirution, tbcse lives Eill outside thc dcjmai~iof When we c211 predict tbat a discasc wtjuld illtbc nol~idcntity.prc>Melnn. ~*7olveso ~rzttcfnpain arid ntffering that the l i k of m y person who had it wotlld ~ m be t worth living on the whole, tve are rnornlty required to pre~*7entthe existelice of people who wouM l~avethe disease. Alternatively, if cve do cause people to exist cvitli severe diseases, tlien we are. n~orallyrequired either to cure them or aflwiatc their symptoms, insofar as we are able, The first scenario that I have described pertains to the impersonal al while thc s e c o ~ ~pertains d to the persense of harm and p a t e ~ ~ dpersonst s o ~ ~ sense d l of hxrln and actual persons. C h e suggests genctic tcsdlig and selective terl-runatic:,~~ of affectecl. ernbrycjs as thc apprcjpriatc actioi~to pre~*7entharm, The other srrggests that the appmpriate actiorl to colxtpcnsate ii>r or pre\rent hrrher harm is gene therrayy or some odier bn11of gellcttic ir-zterve~~tioxl. A persoxi is a f ~ i r t l ~stage e r of developxrterit of the sarllc hrrman orgd~rismof which a11 e m b v o is a11 earlier stage. In this respect, embryos are. potential persons, and f~ilingtr:, ternGnate a genedcaUy dekctive enll-tryo can cause harm by allowing it to develop into a severely diseased a healthy life.= Gent thera~fy person and dcfcadng its iliterc.st in hL3\ai~ig has not beer1 effective ili tredtilig iaost diseases. Because of this, it secrns tbat genctic testing and selective termination of g c ~ ~ e t i c ~defective lfy cmbryos is the only xxredicdlly effective and xrtordlly defe~lsiblewiry to prevent
substantial harm ta tbc pcoplc 1\7bo come into existence.This suggests that soxne lives arc not wortl-z living a~rdaccardin$y should bc prc-"veritcd,an idea that needs ta be defended.
Shauld Some Lives Bie?!Prevented? Biotechnolo'q enables, or cvd enable, us tr:, test enll-tryonic ceUs for genetic nlutations that cause sexre ear-ly-onset cltisorders, such as Tay-Saclts, Hrxrlcr syndrcj~ae,Lescb-Nybai~syirdrc>mc,and C:an,%~andiscase.Tbese disorders have a si~rilarprcjtle. Hrxrler invc>lvesdisruptio11 of cog~iitivcdcvclopment in early childhood and usually death by age ten, Lcsch-Nyhdn causes both ~rrentnlretarcjation and colztpulsive s e l f - - r ~ z u t i i oin b q f l l ~ e irresistible urge to chew tlieir lips and the tips of their fingers, in additiorz to experiencing the sort of extreme pain often associated with gotrt, obviously harms them. Even if they were t~naMeto feel pain, the seltrmz~tikatjun obviously cvould involve significant harm to them. Canamn is a degenerative disease that strikes i~~fants, leading to decay of the nervous system and early death.zcbWe also can, or will be able to, test fix monogenic fate-onset disorders such as Hz~ntington's;and &>rrnsof kirkz~isctn'sand Alzbci~r~er's.Yet, as I have paixitecl. out, tbe gcl-zeral ineffectiveness ofgcnc theral~yand otbcr trcatrxretzts for diese disorders ir-zdicate didt the best course of action is to prevennthen by selectively terlrtit~atit~g the etl-lbrps with the getzetic ~rtzttations that catrse tlie disdcrs.Tl.tis nteans prevexlting diseases by preventing the lives of the peaple who cvonld have them. Such a pract-ice cor~ldhe morally justified on two gmunds. Nonmaleficence ~ q n i r e sthat we not harm people by cat~singthem to ercperience pain and suffering over the balance of tbcir fives. Justice reqt~ircsthat 1\7c not deny people thc same opportu~riticsfor achievcmcnt and a xniliin~dlfydecent life t h ~ arc t open to otbcrs 1\7bo arc healthy or 1\7bo have only xnodcrate to moderately severe dise;ises.z7 milt apply orzly to a s~rtall.t~zrmberof Arguably, the jztstice reqttire~~tent people. For the idea of equal opportu~zivfar a good life i~npliesa certair~ nunlber of years to undertake and complete projects, and most people with severe early-onset gei~eticdiseases haw relatively short lives. Per%l"ii)s this is not the case with C:E wltcre people wlto have tlte disease ofien live &or tbirty years or more. But 1\7bcther one jucliges that a life with C:F should be alfolved or prcveritcd would have to be ixi&~rr~~ed by tbc &ct that its severity spa~rsa b r c ~ dspectruxn, Em111 xndle adult infcrtiliq to constant se. of $lf stice rlzaCter. Rut What vere life-thredteflil-zg i t ~ f e c h n s(d~l~~sidemtkrzs
illatters more than ensariszg cqrxal oppartunicy for achievixzg a decent life is prevcntixzg avoictalzle severe pain and sagering that people will experience once h e y exist. This is what xxtakes lives not vvorth living on the whole, Indeed, it is often die pain arzcl srifferis~gassociated with severely disabling diseases that pmclude people kors~hmitzg the oppormr~itiesnecessary to achieve a decent minimum level of tifetime cvell-being. Testing embrvc,i.ric cells &?r genetic abnormalities is most effective with preimplantation embrps. This can he done once they have reached the eight-cell seigc of development. Tc) produce extracorporeal ernlzryos &or tbis type of tcsti~ig,a woiaan can cake fertility drugs such as C:iiomicl or 1"c.rgonal to induce s-tzperc>vtzlationand a nui~~lzer of eggs that can be reco'17ered tifr fertilizatioxz with sperrn, C)ne adwiltage of producing multiple 1VF" embryos is; that, if a genetic ahtzortnalie).is detected in one of them, it car1 be terxrtir-zatedand anottler, x-ronrral,crrrbrjJo can be selected ixzstead for implantation and furtltcr development. Thmuglt this practice of embryo selection, parents can prevent the eistence of a chdd cvho cvould have a severe disease or disability, t h e r d p preventing any burLJens the disease would barre 011 a child.28 It alsc:, could result in tbc gradual ctinixzatio1.r of a i~~utation from a population t h ~ist at high risk for a certain gcnetic disease. Thc ability to produce ~xtlltipleIVF embrycjs is a necessary biological prenipposition of the inlpersondl harts1 prit-rciple, since at least two etnbrps lztzrst be available for a parent or parents to choose to bring a fzeaithy Ghifd ir-zto existcl~ceir-zstead of one tvllo is diseased. There is anotltcr anyactive feamrt. of this practice. As Kobert Edkvards explains, "ickntifying embryos with genetic abnormalities would oRer an alternative to amniocentesis dtrring the second, trimester of preg~ancy,and tbc 2abortioi.r' iirl vitrc? of a defective prein~lantationembryo . . . 1\7ould be infinitely prcfefczralzle ta alzortic?i.r ill viz/c? at tcvcnc)l.weeks of gregnai.rcy or thereabouts as the results of asxnioccntcsis arc obt;tined."2T~i3stingIVF preirs~fisztation enlbxyos for genetic ahxzortnaliries would be peferdble to testixlg fetal cells for the same by a~~lnioce~ztesis or chorionic vilIrxs sarslf i n g (C:VS) because, tlnlili-e these invasive procedrlres, it wotdd not be paintill tc? a pregnant woman and would avoid certain nredical risks. Specifically, placing a neeiile into the uterus to extmct cells from either the amniotic fluid or embryovric membrane triggers a miscarriage in some pregnancies. C:VS also may cause limb defi>rrruticsin thc fct~zs.In addition, illoral status deper~dson the c2pacit)r &or xxcntaf life, which rcqrxires the presence of cerr~tixzstrllcttares and functioi~sof tbc braixz. Rccausc emlzryc3s lack these structures and hnctiolzs axld thus the capacity ji)r frlezltal life,
tbcy have no moral strttus. So tbcrc wtjuld be ~lotbixlgi~~oralfy ot3jectionable about selectively terininatixzg e1nbr)Bcjs. Enibrycjnic tcsti~igalso wcjufd he lielpfirl in detecti~lgconditkns reszrltirzg &orn chmrnosomdl ahxzortnalities that are not ixzkerited, stxcll as I>o\vn sylzdmrnc. Here too it would be xxrorally preferable to a~.l?ino~entesis xzd alpha-fetopmteit1 arialysis, which detect abnormalities later during fetal gestabon. If these conditio~~s were deenled severe, tl~ena decisiioi~to termillate once the results of these tests cvere obtained would be more n~orallycontraversidl than with embryos, givcr~that Eemses arc at a further stage of biclagical dcvelopxnent. Tcrr~Gnati~ig the dcvclopxnent of cr11e 1VF e1nbr)~cjand transferring a different one &>rin-tpla~~~ition 1\7ould illean that the life of oiie potential pcrsoxz tvas not allolved to bccoxxre actual, and the life of a diFerent potexztial person was alloxved to becorne actual instead. Tlte sarxre nlrtrrber of people wotlld exist; hut they would be differetzt people. Still, whether oxze or a LJ.ifferrnt person is aUo\vecJ to exist does not matter morally Rather, what matters morally is preventing pain and suffering that actual people will have to experience. To the extent that an eml-tryo cvhose ceUs contat11 a disease-causing gcr~etic~niztatirrr~ ~voulciresult ixz prolonged severe pain and suffering in a perxm, we are xnoralfy recyuircd to prevent the disease by tcrr~Gnati~ig the fiirther dcvcloprnc~~t of thdt c x n b r ) ~ ~ ~ . What xxrttst be erz?ipha&ed, though, is that the moral obligatioxz to terxxrinate etrtbryos and therczby prtlvent certain people frorxr comi~rhxnto existence pertains only to people who would have scrtcrc, xzot sir31Ioly rnoderate or moderately sexre, diseases. Only severe cltiseases nlakt: people's lives not worth living on the whole, People with a physkal disorder like C:F arc aMe to form life plans and undertakr and complete pi-ejects within these plans in such a 1\7ay as ta achicm a dccer~t11Gninlum lcvcl ofkvell-bei~lgin tbcir fives, short as tbcy may l3e. As I have noted, ho\\7cvcr, the spectruln of s y ~ n p t a i ~ ~ ~ s s o c iwith a t c dthe disease wcjufd have ta be consicliered in assessil-rg the qtrestioxz of lvell-being ii>r people with C:E In addition, irl moderate fornts of cognitive disorders involvi~lgnlcxztal retardation, such as xxraxly cases of 130tv13 sy11drc3me,people are able to have happy axzd fitlfilting lives. Indeeii, some migbt argxe tbat because people with Down's have limited coglzitive and emotional capacities, they do not experience the same fear and anxiety- about success and failure in life that the rest of us do and conseqrxcr~tlymay very w c l bc happier. Ncvcrtbeless, the fact thdt tbcre is a Eiirly high inciderice of coi~genitalheart disease ixz peaplc with I h w n sprlircjsnc coiaplicatcs tbe issue of the qix~lityof tbeir lives and xxrust be factc3rer.S ixzto any cvalrtatioxz of tl-texrt. '
The bctselilic: of what constitutes the level of physical, cognitive, and esnotiondl filnctionil~tgnecessary for a life wctrth livillg sliould be set qrxitc lc3tv. It is oxdy in se'~~erc diseases, i11valvix1g prolonged pain and suEerix~g arlcl restricted lives, that the ftzrlctioning of perso~lswould fill belmv the haselirle of what counts as a life w a r t l ~living,'a-'heearty-oilset diseases that I m e ~ ~ t i o n eatd the beginning of this section fall into this class, and thereg &eases shot~ldbc prevented. Because they fore lives c o ~ ~ t a i n i nthese cvould f.d_11on or above the critical level, ho~rever,there would be no moral reqrxi~inentto prevcnt the lives of peaplc xvitb 13o~vn's(or C 2 2 BLI~ there wctuld be no xnoral recyuiresncnt ta bring them into e;k;tst;e~icc either, given tbat esstencc itself is xnoralfy neutral and eritails no olzligation ta cause people to exist with good lives. With respect to the q~lestiot.1of tvhether a life is tvorth living, it is imporrarlt to disti~lgrisl~ early-otlset ge~leticdisor~lcrsof the sort I have been discussing, wltich affect people h r n birth or early childhood, &am the late-onset genetic disoders of Huntingon's, Varknson's, a1111 Alzheimer's. It: is also inlportant to d i ~ t i n ~ q i sdisorders h that affect people in mid-life from tbosc tbat affect them much later ill life. In llaarkitlsonS and Afzbeinicr's, tbe earlier-onset and illore severe fiorr~~s of tbe diseases are correlatccl. witb a hig;ber-~?e~lctrance gc~ieticcomponc~it.Thc semrity and time of onset of symptoms agecting adults are crucial to assessing the ~*paIue of their lives on the whole.
Life Stages Thc onset of synllftolas in pcoplc witb Huntilzgon's iaq rangc a~~ywherc from agc thirty to sixty and these incltdcie prcogrcssivc loss of ~ ~ ~ u sconcfc trol and dementia. C;c~ieralfy,tbcy dic witbixi fifteen years after onset. Prior ta tbis tinic, they can hLjv~ normal lives with comparatively high levels of cogxlitiw and physical firnctioxling iirr a co~lsidcrtlhtenumber of years. h tr).-ing to deter~~zine whether people's lives are wofth living on the whoie, we tleed to evaltrate the quality of their lives in terrlls of afl the stages i n them. C>ualiq of life is a function of the presence or absence of pain and suffering, and of the cognitive, emotional, a1111 pltysical ability to have opportunities frx achieving a decent 1IUninlum level of 'urell-being. This incfudcs tbe ability to form a life plan and to txndcrtake and cornpletc projects within such a plan, C3i>viously,this dcterininatior~will be subjective to a certain degrcc, Nevertheless, l3-y setting a h ~ threshold 7 of what counts as there can be reasor~ableobjective agreerllcxlt al-torrt a deccxlt xx~inixritrrx~,
lives that arc not worth living because they fall bclo~cvthe baseline. With though, tbe radical diffcrclice bclate-onset diseases likc Hu~itingtoli's~ tweexl cognitive and physical filnctioning heforc and after the orlset of syn-1pto"rts lztakes it dificdt to assess m7er;lll cjlraliv of life ii>r the people who have dielxr,This is SO even if \rye can agree 0x1 a ger~eralobjective xneasure of quality at prd.cular stages of life. One cwky of measuring lil'etime qrrality in severe adrrlt-onset diseases is to cveigh the level of normal cognitive, enlotional, and pltysical fttnctianing per year livecl. agdilzst tbc level of pain, suffering, and disalziliv per year lived. Frcxn this 1vc call rc3~1gEZlycalculate a11 avcragc lcvcl of well-bcirig &or the person's esltirc lifc.""ln this ~nade't,the rmre severe the pain, suffering, ancl disabiliv associated tvitll die disease, the earlier the tirne of onset of syq7ton:ts, ancl the longer the period of rime between orlset and death, g the life is x-rot tvortli living the strc3nger will be the reasox1 for s a y i ~ ~that on the whole. C:orrespondix-rg there will be a stronger reason for preventing such a life by ternlin~tingthe embryo known to have the mutation that causes the disease, a s s ~ ~ m ithat ~ l g tlte risk of ltaving the disease is kno~cvnto be bigh, For a person who first experiences tbc degenerative physical and cognitive sylnptoms of Huntington's ;at age thtrtr)r-five and who dies at 6fv% the severity of tbc pain and sugerixig hc experiences in his last fif'reen years may he had enough to outweigll the good filnct;o~litlg he fiad in fiis first thirq-fiw years arlcJ average out to a level of liktime well-beix~gthat falls below die decent rx~ir-zirrttrr~~, This assessnlellt is illfluellced by tlte idea that we ltave a tenlporal bias toward the t.ilt~ire.Thatis, we care more about what we will ex~~erience in the tilture bemeen the i3resent and the time of our death and less about what 1vc experiencccl. in the past." Mc3st of us prcfcr a life tbat matures to one that degenerates, a life thdt starts poorly and gcts better to one that, travcrsi~zgall the same points, sstrtrts 1~cUand then goes pragrcssively dc~TcvnhiIl.'"f this is plarrsible, tllexl the sul7jective valtze of our last stage of life will be disproportiotlate to the value of ntller stages with respect to its overnil qualil.y."l:'hcsuggestion is that a long and pairzfrll iinal stage of one's life may have enouglt disvaltle for one to conclude tbat tltc l i k is not worth living on the whole. Accori.lingly$if a parent or yaxnts can foresee such a life trhrouglt the results of genetically testing the cells of an e m b r p , tbcrl tbcy should terinilzxte the e r n b y and prcvcrlt tbat life and thc existence of tbc person who wc~uldhave it. C:oiisider nc3\\7 a variant of the I-S~l~itingtan's cxa mple. Srxpposc tba t gcnetic testing of the elztbrp cotlld predict that s)..mpto~l:tsw o d d not q p e a r
until age fifty, 0 n c still xnigbt claim that the pain and suEering caused by tbc disease iii the last ten or 6ftce11 years of the person's life ~vctuldbe sct ~ e \ ~ e that r e they would outkveigh even the goocl fifty years and dirts rmke the person's average lifetime well-being fill hetc~wthe decent minimum, Aithough it would he xxrore difficult to sustair~than in the earlier exclrnple, here too there nlay be a principled reason for ternunating an enll-tryo with the Huntinson's gene.. It nlay weig1-t tlte decision in f m r o f pi-eventing the eistence of a persoil cvlto cvould have the disease over carzsixlg him to exist with a life thdt has a siglifificandy loilg and wretched last stagc. Moreover, sagering may begin much earlier t h ~ ntbc time of onset of syn1l-ttaias. Knc>\\7ing thdt 011e is at risk of having the disease and the sy~nptcxas it entails can itlftluence a negative yerccptior.1 of the quafiq of one's life even befort. syrxrptorns begin to appear. Alter~~dtively axle could take the view that, with adrrlt-oxlset diseases, the person with the disease would have the a u t o i ~ o n ~and y responsibility to decide &?r himself cvhether to go on living beyond a certain point. Tltis would sltifi the locus o f kcision-making m d responsibilit-)l h m the time before birth to the tiinc bettveen the onsct of sylnptaias and death. It also wctuld shift the respon"bi1ity &or decisirm-laakilig from parents or otbcr with the convicparties to the person wit11 the disease. This is co~~sistent don diat the wlrxe of a life is largely (though not: ex~tirely)deterxrtined srrbjectively by tlie person whose life it is.This vall~elids much to do with the nhjective ~~otioxls of digniv ancl control over Itovv the rer~lainderof on& life sltorlld go. Bat these nations invite questions about voluntary eutltanasia arid assisted stzicide, which involve legal issues that are b e p n d the scope a parent or parrtnts of this essay. More important for present p~~rposes, wctuld be justified iii preventing a potci~tialperson fro111 cxisti~igif a latcallset disease the person would h ~ v cirlvolvcd scvcre xnental and phyGcal s y ~ n p t o i ~ ~au c~~lsiderable ~ld period of time between tbe onset of syn1l-ttoxxrs and death, The asyr-rtlxretry in our attitudes tc>lvard earlier and later periods of life and tlie persotl-affectitlg principle jr1stif.j arl objective deterxxrixlation that such a life on the t v l l ~ l ew r l l d not be vvortll living for any person. A mutation in the gene for beta-an~yloid precursor pmtein (UAPP), when cornbilled with apolipopmtein E (APOE), has been implicated as a cause of Alzhcin~er'sdisease. RAPP gathers iii the spaces between nerve cclls in the braill, while APOE transports cholestcrc>lin the Izloodstreaxn and plays a role in ccllular repaimand regeneration. APOE coiaes in thrcc allelcs, e2, e3, ancl e4, f3atiexlts tvitll the BAX313rllutatiox~ancl the e4 alIele of
APOE dcvclop Alzheinier's much earlier t h ~ nthasc with tbc EEAllP mutation and tbc c2 or c3 alltlcs.3i The average age of onset is sixq-eight years in people with two copies of APC'E4, sewnv-f-iw )rears with 0x1s copy, ancl eiglrry-farzr if they have no APOE4 genes, Suppose that a person witlt one or tkvo copies ofthe e2 or e3 diiele de\relops the disease at eil2hl-i;-five. Giwn tltat she alrea* ltas lived otrt a nornlal life span, that slte probably would die in a t2.w years, anif that she has had no major diseases or disabilities prior to this time, the balance of benefits to burdens in her lik as a whole wtjuld indicate tbat her life is ~s~ccnrth living and that there would bc no reason to preveiit it. Rut suppose that a persol1 with m70 copies of APOE4 has a r ~ ~ u cearlier-onset h h r r n of the discdse thdn tbc average &or this type. If synptorrls begail at age forty or eartier and the individual's conditiol~deteriorated gradualy over a period of ~ v e n qyears, then one c o d d argle that the balance of burdens to bellefits in that person's life as a whale would make it not worth lking and thus provide a reason for preventing a similar life in the firtrrre. It is not SO much the final stage of the disease that is harmiirl to tltose affected by it, since they may no longer be a\%~arc t h ~ they t have it. Rather, the h'jrr~~ consists Inore in tbc sufFerilTtg asand sociated with expcric~icingthe gradual deterioration of one's r~~ental physical fuxicti~ningover a prolonged period. Adinittedly, these assessments are always ~?robabilistic,as rr~anypeople with RAPP and APC3E4 never d e ~ l o pAlzheirnerk. Nevertheless, people with two copies of APOE4 have about a 90%)chance of eventually developing Alzheimer's. If genetic testing of embryos could be pe~-t"ectedto the point where the diEerence hetmreen the e2, e3, and e4 alleles ofAPOE and their p~-obabiliwof penetrance could be determined, and if the onset of sy~nptam"n people 1%7bodevcfop frc~xnthese crnbryos could bc predicted then this could inf ucricc decisirm-makwith a high degree of probalzili~~ ing rcgardilig which lives are alfc>k%7cdand which arc pmvcnted. What is crucial is 11ot jltst the nature arlci progsessioil of the diseclsc, hut dso it OCCUTS. Pail1 ancl suRerixlg in the last stage of o n e u i f e rrlust be weiglled agaixlst the p s i t i w experiences a i d achievements aft"orded by normal rnentaj and physical firnctioning in earlier stages. Fifty years of nornlal fE~nctionillg should be enough f i r a person to complete many of the pmjects in her life plan and make &or a life that is wctrth living. If \VC accept this, then the fact bcgixls to deteriorate at agc forty Izy ittbat a person's normal fu~ictioni~zg self is not enough tc:, suppart the claim that 0 x 1 balance her life is not vvortll living and that she should not have been brorrght illto existence. 1djj1~11
Sollle people have lives ofjust thirty ycars that are fill1 of achievements and happiness. A shorter lifk can be very wct" w r t b living." But if the pain ancl sugering it1 one's last years are severe, and if the xlzl~nherof these years is cor~siderdble,then this may weigh the ctccisior.1in favsx ofprevet~ringthe person from cornit~ginto existence.l'he experi"':xe of severe pain and su6fering, more so than what it implies about limited life opportunities, grounds the claims that a person's life on bahnce is not .vvort-lt living and that it is morally 'urrong to cause a persoil to exist with such a life. Still, we have to weigh the relative inlpartance of cognitive and physical functic>i.rixig&or different people in evaluatixig qrxalit)l.o f life. Czonsidcr the 111otor-nertrc3n discasc alnyc~trcjphiclateral sclerosis (ALS), where 5 to 10%) of cases are fartlilial. Mlttatioils in the gene exlcoding the exlzyrne superoxide disxtlutase 1 (SUI31) account for 20%1of cases of faxxtiSiaX ALS,-i5 The adult-onset form of the disease is atltosomd dorniilar~t,with syrqtonts appearing aru~rndage f0rt-y or earlier. A j~lvenile-onseth r m is autosomal recessive, In afl FanuEal cases, perretrance is close to 100 '%. Stll7pose that the presence of the mutation in the domindnt type could he detected ly testt disease could bc prevented only Izy tering elabryonic cclZs, and t h ~ the i~il~tating affectccl. elabryos. C3ne might think t h ~ there t wtjuld be strc3ng i~~edical and moral reasons to terminate such embr)~cjs, given the degree of petletmtlce, the sylnptolzls associated with the disease, tlze time of onset, and the likely drtratioxl of the disease. Yet the case of the brilliar~ttheoretig that a person cal physicist and costnofogist Stephen H a t v k i ~ ~ilttstraces can sutf5r from a severe physical dsability as a symptom ofALS for cveU over the balance of his life: and yet maintain a higb level of c o p i t i w h n c tionitlg that makes life: very much worth living fbr him. It would be &&cult to adduce reasons &or prevciitixig his life, despite tbc Fact that ALS is a severcly disaldixig disease. On thc other hand, &or people who vdue physical functioi~ingvery higMi-ity (Eor example, atMetcs, or dancers), semrc physy them to jtldge that 0x1 bdlar~cetheir lives are x-rot ical d i s a b i l i ~r t ~ ~lead vvorth living, even if their x-rorxrtal cog~~itive fur~cti~~xli~lg rerrtaix~sintact. G m t e d , people can adapt their preferex~cesand life p x l s to adrrlt-onset diiseases and the linlited opportunities they entail. L3trt it is not so easy to do this if one has to endure conseant pain and suffering aver a long period of time, eveciaUy if symptoms w e a r early in one's life. Furthermore, in tbc case of solneonc like Hawking, if thc pain associated ~ v i t hhis phyGcal disability 1vcrc so severe that it adversely aiFectccl. his cognitive functioni~~tg, specifici~llyhis abiliy to do physics, tbcrl 1vc lnight ask whether he would believe that his well-being tvas nt a level high ex~ougilfor him to jtldge that
his life was worth Iivi~ig. These considerrltiorls suggest tbdt h o ~ va late-onset disorder with xiriable syrnptolTls arid variable degrees of pain and sugering affects a per-son5 qzraliry of life tvill depel-Id on the type of life plan the person already has cllosen and crrltivatecl before the or-~setof syrxrptorns.A person's life in progress is shaped by the person's values and preferences. And tltese are not tlte sorts of tltings that can be predicted on the basis of genetic testiitg of the embryo or eanly-stage fetus from which tlte person dcvelops.TI~ispoint likely would not arise in a case where juvenile-onset ALS could be predicted on the basis of gcrlctic testillg of an embryo. Like other early-onset ncurodcgeiierative diseases, tbcrc wc3uld be a dccisive reason b r prcver-Iting the life of the person who would h m the disease. It1 moderate and trtodemtely severe diseases with a ge~leticcause, we could argue that cve m~orrldnot be rPqttipc>dto premnt people fiam coming into existence with tltese diseases. We m ~ u l dbe pet-;-rnifled ta prevent them &m existing if we knew o r had good reason to believe that existing wctuld entail solnc h'3rr11 to them. But we wctuld be recyuired ta prevent tbcir e;k;tstc1ice if it entailed semrc disease and coi~sideralzleharm. In theoretical terms, an action is xnoraay rccylxired if it is suppartcd by a decisive reasot.1 for doing it. An action is rl-~ordjiypertllicted if there is 1-10 decisive reasot.1f i r not doing it,What pen~ri~"; it is the absence o f a reasox1 srrfficient to gl-ourid a proliihitio~iagilitzst the a ~ t i o n . 3111~ practical terms, the differof the probabilence bettveen requixments and pernGssions is a f~~nctiorr ity of having a disease and tlte magnitude of harm in tlte severit-y and &ration of tlte synlptoms associated with tlte disease. If the p h a b i l i t y of having a disease and the xnag~iitudcof h'3rr11 arc high, then there is a dccisive rc,~s011h r preventi~igthe life of a persoil who 1%7ouldhave a severe disedse..Tbus1vc are morally rcqr1ir-c.d to prcvciit tbc eestcnce of such a per~ the person to exist. ff tlie son, or trtoralty prohibited f i o t ~causing pmbabiliv of having a disease and the trrag-Iitnde of hdrrn arc Iokv, then there is no decisive reason for prft'17entiilt-fthe life of a person who would have a nloderate disease, Thus mre are nlorafly pernlitted either to prevent the person &m eslsting or to cause him to eslst,The harm would not be so great as to constitute a decisive 1-easonf i r preventing the life of a person who would experience moderate pail1 and suffering. 1x1 110 case, though, wctuld 1 ~ bc e i~~orally reqt~ircdtc3 cause people to exist xvitb healthy lives, since e,urtstcncc is i~~orally ncutral and causing them to exist does not make the111 better off.
Some xnight bc disturbed by the idea of xnak;ing decisirrns alzout embryos on thc basis of the prc3babilif-r of dcvclopirlg & disease, given & gcnetic ~xrttt;ltioi~ Even with a farl~ilyhistory of a genetic disorcjer, the gene in qtlestior.1 may not exprcss itself in every ~nernberof the fa~rtilyMoreover, even if one inherits a gene er~~%iliilg a fairly high pmhabilirl; of disease, diet and lifest)ite may p ~ v e n it. t This is stlpported by Holtzman and Marteau's point, noted in chapter I , about the camplexisy of genetics in common cjjseases in the ligbt of the incomplete penetrance of genovpe in tbcse diseases. Rut it is not just thc probat3ility of having a discase, given particular genctic mutation, that cor~sdtutcsa rcasor~for prcvciiting a lik. 1x1 addition, the ~xragl~itzlde of l l ~ r ~erwailed rt by the syr~tptornsof the disease ~xtttst he considered, as well as the time of onset of ymptolrrs arld the time betkveei1 onset ard death. Earlier, 1 specified these t h e e crjeeria in assessir~g whether a life is m t h living 011 the whole.The probability of penetr-ance is a filrthei- criterion that must be specified in julJging 'urhether a li& should be prevented. So, assullling that a defectiw gene can he detected at whether life tbc crnbryoruc stage, four critcria will fikrure in dcterini~li~lg c j the gcnc: (1) tbc should bc prevente""l.by terr~inatirzgthc e m b ~ ) ~with probalzility of gc~ioty.picpenetrai~cc,or bow likely it is tbat a gcnctic mutation will cause a disease; (2) the severitry of the disease in its s)irxtptoms; (3) the tixrre of oxlset of syrxrptoxns; ar~cl(4) the tixnc betweerz onset arzcl dea tb . It wiU he hejptirl to think of the obligxtion ta premnt a life as a matter , along a continrltrm bettveen requirements and permisof d e g ~ e f.dlling sioi~s.Tl?ieobligdtialz will he stronger or weaker depending on the strel~@,rcb of tbc rcasolls h r or agaixzst preventil~tg life, which iri turn will depend on bow a particular instance of disease fits the four criteria specified &bc>vc.In a disease with high p r c ~ h a b i l of i ~ penetrai~ceand with a11 onset of severe syn-tpto"rts early in life, there is n strong, decishe, reasor1 arld ohliptiozz to preven~thc:life of the person who would l ~ v it.Tlze e ohiigatioll is eqrrivalent to a moral reqtrirc~nent.It1 a disease with a low pmbnbiiiw of penetrance and wit11 a11 onset of moderate S ~ M I ~ ~ O M Ilater S in life, there is at most a weak, if any, reason and no obligation ta prevent the life of the persoil w l ~ owould l~aveit. Instead, the nature of the disease would be such as ta ir~volve perr~issionto choose 1\7bcther or not ta bring alzout life with it. Accordixigly there 1\7cnuld be at 111ost a weak rcasctn and no ot7Ligation (permission) to tcrmiriatc an emlzryc:, with a low-perietrance gcrlc predisposing to a multifactorial form of lxrild late-onset bpcrtension. In
contrast, there wtjuld be a strong rcason and obkgation (~ytliremcnt)to tcrr~Gnatcor not select an embryo with a high-penetrancc gclie causiiig a ~ e \ ~ eearly-OIISC~ re I X I C ) I I O ~ ~ X Idisorder ~C like Tky-Sachs or 1,esch-Nyhan. Arguably, there would he an equally strong reason arld ohiigaticzr~to ter~rtinatean embryo wit11 a higll-penetrdr~ce ger~etic~rzvtationcausing a later-onset disease cvitlt prolonged sexre synlptams beginnit~gin the n~ield e stage of li&,This mratllcl be a case mrhei-e tlte persoil aft"ected by tlte disease would experiellce its symptoms fbr many years before dying. Earlieroi~sctforms of H~xntir~tgton's, Alzhcin~er's,and perhaps even ParLl~tsctn's i ~ i g h t into this class. Thc reason and ob1bligatiol.r to terinillate tbc cmbryt) and prevent the life in thcse diseases might be as strc3ng as 111 tbe chidhood diseases I r~~entiot~ecf becatrse the adult with the disease rnight srrffer at least as IXIUCII as, if not I X I C ) ~SO ~ tll~111, the child.This would be not: only a reflectioi~of a substantiaf nulrzber of yetars of suRering, but also of the degree of suffering that comes with experiellcing the decline of one's pltysical m d cognitive capacities anif a more hei&tened sense of dread of the future. C3thers imy be disturbed 1z-y tbc qtlcstitrl~of 1\7hcthcr a hrzma1.r life is wctrth livi~lg.Thcy may cite the s a i ~ c t i s y - c -doctrine, main~iiningthat all life is sacred and tbcrek~rethe qrxestion of the value of a life should not even be raised. But this ifoctrir~erejects all q u a l - i f cor~sideratior~s and thus fails to cor~siderthe subjective cxperiex~ccof living with ifisease.37 In d.oing this, it effecti.vely bases the idea of s a n c t i . ~on the biolo@cal life of htiman organisms rather than on the psy?fcholof;lcallife of persons, Xr is our psychological lik that matters to us and, in some instances, pain and suffering in this lik may be so severe that it would, not be worth having. whether tbc This suggests a further inipartant point. When consiclieri~~g life of a poteritial person ~vcnuldor ~voulcfnot bc worth livir~tg,it is not any burden on thc parents, but instead the burden of discase or1 tbc person who would have to live with it, which should infc~rrl-tour moral reasorling.
Giving Priority to the Worse Off Two additional objectians might be raised agdinst n.ry ai-guxr~entsaxld tlte principles on wltich they rest, Specifically; the impersonal conlparadve principle could be interpreted in such a way as to rcqrxirc us ta bring into e,urtste~icconly people with no discases or disalzilidcs of ai-ry sort over the course of their lives. It even might retluire us to preverit tbc lives ofpet>ple with or~lya genetic predispsition to cerrait~diseases. Moremet-, it could
lead ta discriniination against people with disalzilities.Thcse ot3jections can version of egalitarianism, be Inet by appealiiig to a partic~~lar Eq~xdIitydesignates a relation between people or diflereilt gmltps of people. I t is i~~vokecl when we tvatlt to edlxate how some people cotrtpare with otbers wit11 I-espect to the distrihutiotl of goods. Egalitarianist~~ is concerned with the distributive and comparatite question of dro fras wIftrt, as distinct from the utilitarian concern with the aggregatite question of frow rrrfriif rltere iis. There are two iliterpretations of egalitarimism in the philosctphical literature. C3nc says thdt ecylxdlity as such has valtdc, and that inctlualit.)8of any sort in the distribution of gt~odsis xnoralfy olzjecdoi~alzle. Thc other says t l ~ eyudlit.)8 t as such is not w h ~ tllatters t xnoralfy, but instead and clairns of the worse c>@.38 that priority should be giwn to the ~~eecls C112 this vietv, irlequaiities are n~orallyperr~~issible provided that they tvork to the benefit of the least ad~~ntagecl individuals or groups. Tlte secorld version of egdlit;?rianism is captwecl in John Kawls's djffei-ence pi-iz~ciple (12P) and maxinlin rule (MIX)." DP states that inequalities are to be arranged sa that they are to the greatest benefit of the least advantaged. MK. strttes that, itz ranlung altertiatives, we should adapt tbc alternative the wctrst outcomc of which is superior ta the worst outcolne of others. Tc3gcthcr, I>P ancl. MIX yield tbe wctrsc-off priority prillciple. For prcseilt p ~ i r p o x httlie worse of-t:'~repeople with severe disease and disahili~,while the better off include people with r11oderat.e to ~xtodemtdysevere disease, as we11 as diose tvho are by all accounts healthy. Regal-ding health status, ""better otf'band "x$rarse off" may be construed in compasative terms involviz~ghow one gmup hi-es relative to anotlter. O r they may be co~~strued in abscrlute terms, where one is better or worse offwith respect to a1.r absolute bdselil~teof a dcccnt 11Gninlum level of adeqrxdte xnental and phyGicdl f~tnctionirig.The lower a n itldividual Falls below tbc baseliric and thus the 1\7orse off he is it1 tcrrns of diseasc, the stronger will be his claim to have his healtli negcls met with ap~3ropri"kntrledical trcatrxrexlt, Co~~verseIy, the higher a11 i~ldividudlfi~ltsabove the baselixle ancl thus the better off he is ill terxrrs of health, the weaker will be his clair11 to n~edicalti-eatnlcnt. L3eyand some point above tlte critical level, one's claim to medical treat~nentwill ltave little, if any*moral force. As 1 will argle in chapter 3, medical intervention for people whose beafth stams falls above tbc critical lcvcl should be considerecl. enhanccrnent rather than trcatlllent ancl. pertains to people's prcfcrences rather thd1.r t c ~their needs. Czlaims based o1.r prcfcrerices have much less moral forcc than claims bdsecl. on needs.
Fairness is onc fcEedtt~reof tbc second, "pioritarian'hcrsion of egalitarianism, A Fair distribution of a good like imedical treatment rcylxires that different peopleS fiealth needs be met in proporriot.1to their strclngti~,Fait-. I I ~ S Sis n l-elative Irratter, n tnatter of how a persorl making a claim is tren this basis, we can cIearly distingtish betweex1 irltcrvejitions that restore people to or mainbin them at a rlortl-rd h n c t b n d level, and interventions that raise t l ~ e mabove this level, Furtl~ern~al-e., I cvd argue that medical and nloral reasons for genetic ix-rtervention have more %weight at m d below the baselille of adequate hnctioning and less weight above tbc baseli~ic.This is because thc weight of the rcasctns supporting clainis to d s people i ~ ~ a k i l thcse ~tg receive trcxtmcnt is prc3portional to the ~ ~ c e of claims, and enhancclnci~tsdo not pertain ta peoplc's needs but ta tbcir p ~ f e r e n c e sabove the criticid k'17et tvhere their basic health needs have been xx~ct. First, 1 discuss gene therrayy and explait1 wlry it has yet to become effective &?rtrrati~lgmost genetic &seases.Tbis will serve to reinibrce n ~ ygeneral argument in chapter 2 regdrdjng the prevention of the lives of people wha would experience severe pain and suEering beca~rsrof these diseases. I distinwish soiaadc-cell gclie therapy from germ-line genetic alteration, Elaborating further on the discussios~of all~catiilgscarcc medical resources, I consicier 1\7bcther 1vc should give higher priority to trcati~igpeople with sewre but rare rnor.loget:licdiseases, or to people tvith less severe brit xxlore cojxtrlion r~itrltifactorialdiseases. The xirxrx~berof people w l ~ o starzcl to berzefit froxrr treatlrrexit, as we11 as the extent to tvl1ic11 they benefit, aEect haw equality anif fairness are evaluated in tlrus context. I dst? examine the differences between gene therapy for physical disorders and gene therapy &?rcognitive cjjsoders a l ~ dexplain why the latter c\rotlld have a significant inipact 011 perxxufiiclienti~and our understanding of hencficcnce, Shiftilig to geslctic enhancement, I argue that there arc ncithcr illedical nor xnoral reasons for this type of intervention. I give five reasolzs wlry genetic exlhancernent shot~ldbe prohibited. Finally, I address the
claim that there is a slippery slope fro111 treatment to eribai~ccmcnt,or that tc:, prcvcrltiarl and treatinent inthe negative eugenics corrcspol~di~lg evitably slides into the positive ctzgex~icscorx-espoi~cSingg to ex~hzlncexxrer~t, X xrtaincain that this claim can be rrfected because the slippery-slope argtxxrexlt on which it rests is unsound, olvix~gxxraix~fyto the fallacy of assirrrilation and unsupported claims abatrt causatioi? in its premises that render them Glse. ProvicJczd that the aim af genetic intervention is prevention or treatlnent af disease, a l ~ dpx-ovided tl~atadequate policy guidelines and legislation are in place, ~legativeeugerlics call be ~neciicaflyand nora ally JustiGed.
Gene Therapy: Problems and a Paradox Roughly, gene therapy coi~sistsin the correction of a m t a t e d gene or the illsertiol~of an additioi~alnormal gene into a perxxTs somatic cells to treat af germ ceUs a disease with a genetic cause. In contl-ast, genetic alteratio~~ (gmnetes: sperm a l ~ degg) at t l ~ een~l-tryonicstage of a hurryan organisxr~is a farm of disease prc"ventio11. This sccctncl. type of genetic i~ltervcntion should not bc considcrcd ""thea~>y9'9?ecausc whcri the gametes arc altered therc is no existi~lgpenon who 111ight bcnefit fi-c11n this procedurc.2 ""Tl.ter;lg?j~"knplies that there is a disease to be treated, and it is not exnhryos or early-stage &ruses hut persotls ( a d , arptahiy late-terr~l&ruses) wllo have diseases and their respcctiw syn-lptotrts,L>efective allelcs of genes in embryonic cells may be the causes af diseases, but diseases and their syn1i3toms do not manifest themselves until the organism has reached a further stage of devetopment, Like gei-m-line genedc alteration in emelnbryc~sfor gclietic abnormalities and sebryos, testing preiinplx~tatioi~ lecting tbosc with abziormalitics for tcrrrunation is a prcvciitivc rather than a tbcrapcutic stratchy. It is desig~cdto prevent semrc diseases by preventing tlie exister~ceof the people w l ~ owould have them, Sonlatic-cell gene therapy may determine or presewe the i d e r ~ t of i ~a person, dependil-16on the sragc of develop~netztof the organ is^^^ wllen the i~lterventiantakes place. It also del7encfs an whether the trait or function treated is physical a r nzea~tai.In chapter 1,I said that the arfdition o f a normal copy af the gene to treat Ashanti de Silva's ALIA-SCID would not likcly alter bcr identiv*For it wctuld not sigriificai~tlyalter hcr memories, belie&, desires, and i~~ttentions or the ways in 1\7bicb tbcy were intcrconnected. I-Sc>wever,sctmatic-cell genc therapy desigried to correct or treat a coglitive or aEective disorcfer tvould be xxrore likely to alter axle's i d e r ~ d ~
Thc xnaipulation of the relevant nertrc>tral.rsmittersor rcgic>i.rsof the brain tbat generate and support rnc~ltallife 1\7ould directly affect the very nature of the lzterltal stales definitive of personhooil and personal identit): thmtrgh tirne.Tlze gerie ther~pyfor the two Frei~clibabies tvith a differer~tb r r n of SCIf), also r~~entioned in cliapter I, wtrfd be identiq-detenrtit1i11g as weK AltX~oughthis disorder is pl~ysicalrather t l ~ a nmental, t l ~ eintervendon took place before the babies had d e v e l o ~ da unified set of mental states to be full-fledged persons. But whereas the physical therapy in this case wctuld be identity.-dctcri%liing bccause it occurred at such a11 early stage of dcvelopiaent, cognitive tbcragy for a long-term xnental disalziliv xnost likcly would be ideritity-determi* at any stage of one's psychological life,As 1 will explaii~,this should lead us to question whether intervetztioi~s to treat cog~itivedisoders could be considered tlreraperttic. Germ-line manipdation w t d d determine rather than p s e m persorIaI identity because it \\ro~llcientiiil a completely diEerc3nt set of biological and mental properties of the person who comes illto e;?tlstc.nce after the manipulation. This individual would be distinct h m the one who worlld have e,urtstecli h ~ the d ii~anipulationnot takcri place. The biological properd ties wt>uld be completely dilrercnt because the i l ~ t e r v c i ~ t~i \~~io~u loccur before tbe prc>cessof cell differentiadon h ~ bd e p n , or while it still 1\7as in pmgl-ess, Even slight changes to the biological properries of a httman orat the ez?-thrpr.licstage w d d catlse different psychological properganist~~ ties to develop and thus sdect betkveen which of a r~vlrzberof different people wotrld come. intr:, existence,The same could be said about in utero fetal gene therapy, Although the insertion of a normal copy of a gene to treat a genetic abnormality would occur afier most cell &Eerentiation had ~ i k c nplace and inclpierit orgar~systems bad formed, tbc biological and physical life cof the perso11 who caine into existencc would bc dikrercnt from the one who 1\7oulcZ have existccli 1\7itbout the tbcrapy, And 1\7hetbcr one exists with or widiotrt a ph-).sicai disease or disabili~tvill deternine to a slgnifical~textent the x-ratttre and coiltent of the rl~critalstates in virtue of wiiicl-1 a l l it~dividualis and r e ~ ~ ~ aone i t l s a t ~ dthe same person. Sontatic-cell a d germ-line geuretic manipulation at an early stage of development wouIci have the same eEt"ect on persr:,nal identiv, Still, these two types of intervention diEer in at least one crucial rt.spect.?'he first determines the iclientiv of one person as distinct from another person who wt>uld have e,urtstecli?\7itbout it.Thc second call dctcrriGnc the iclientities of l n a q future people, given tbat thc effccts of the m,rnipulation are passed on to oEspring,
Somatic-cell gclie therapy is not yet feasible for trcatiiig the ma;borit)r of genetically caused disexses. For oize tbing, gene therapy is priniarily rcleva7t to siltale-gei~edisol-ders, arlcl polygei~icdiseases such as coion cal7ct.r irlvolve severnl ger~etic~rt~ttatinns. Further~nol-e,d~mjrtosolzlnldisorders such as Down syndmrne involve large segx7ter:lts of D N A . that are not anlenable to treatnlent. In adclition, the monagenic diseases tltat nfigla be amennble to gene therapy ar-e recessive rather than dolllinant.";~c.cessive & s o r d e r s e r a sngle copy of a normal allele is sufficient ibr functionI fix persons-could be treatable because ining withi11 the n o r ~ i ~ arange ~ i g dcxe of the ab~iorinalallele serting the copy into cells c ~ l l ~ i i ~ ai idoulzle could be enough to eristare proper cell filnction. I3omil~tantdisorders, on the other band, result even whe1-1 an affected individual has oidy a single copy of the defective alIele in his or her cells. These disorders would be tmatable only by correcting the mutation in tliat allefe. Gene replacel~zent cvould be superior to gene addit_ionbecause its potez~tialto correct a mutation could prevellt bath atltosomal dominant m d rrtcessive diseases,? 11rcseiitly9ho\vcvcr, it is not passible to correct a mutatioi~but oilly ta insert an additional copy of a gene into the affcctccl. cells. C3iily a few atrtoscti d rccessivc and X-linked disorders can be treated with gene thera~zy. In theory a recessiv~disorder likc cystic fik>rc)sis1\70uld be treated by delivering a nortrlnl copy of the critical allele into the aBPcted cells so that the pdncreds pmduced t l ~ enecessav enzymes b r food absorption a r ~ dthe dands in tlie lining of the bror.~chidtubes functiolied p p c r l y h an Xl i n k d dison-ter like hemophilia, a normal copy of the gene coding for tlte pr-otein that contr-ols blood clotting could be defivei-ed thr-ough ix~jectians, In practice, what has plagued the eft;brts of gene therapy to control or cure disease has bceii the lack of a suitable vector to deliver therapeutic gclies into cells and xnaintallz them in prcjper wtjrEng ordcr.Viral vectors have bee11 the most cctiai~~on xncthod used to datc, specifically illactivated adenwiruses and retrc3vir~tsesused to carry pieces of I ) N A ; into cell ~izlclei. Vet this metliod has bee11 largely zzxl.;~tccessf~~l hecdtlse these swippecldown viruses do not provide a stable platform b r the genes to operate efijciently The Fact that tlte respiratory tract consistr; of rapidly &viding epithelial cells means that frequent ii~~ecti.ons of the vector carving the gene would be needed.. Some of these viruses are not large el~oughto carry a fill1 hu111an gclie and alf of its " ~ ~ v i t ~ h ewsh, l' ~ e other viruses may prc)vc>kea11 adverse responx frcroin the in~muncsystcrn. In additic~n,if the vectar I V C ~ C not targeted precisely to the gclie or gencs 111 qtr.cstion, then tlut vectar cotzld adversely aEect other genes ancS ir~terferewith their
functic>l.rs,which could lead ta various cancers, Or the delivery virus xnight rcvcrt ta its norind1 active state ifit ilzteractcd 111 a certain way with natural ~*7irztses in people's lzr~?gs.Firtally a person c o d d develop inttrtzt~zi~ t.o the viral vector, in which case the treatrxrerzt would cease to lye eEective.(~ The risk of harm to individuals tlndergoing gene theray): has become palpably e v i k n t in the wake of three recently reported deaths resulting from complication^ of viral vectors. Jesse Gelsiziger had a mild fbrm of o n ~ i t l ~ i ntranscarban~ylase e (C3TC) deficiency, whereby the liver cannot ~ cfood. t Hc died in 1999 process alainonia, a tctxic breakdc>wiz p r ~ d ~ of &11lowi1zggcizc theral~ywith a viral vector ilztend~c1.to correct the disorder at tbc Universit)r of Pe.nizsylw~zia.~ Several months later, it was rc-ported that jarrres Dent, who had been diagl~osedtvitll a tenrriizal. form af brni1-r cancer, tlt.zdewemt gene therapy in %"orontoand died kom con-tplicacioxzs of rile tres:atmerzt.Ulso,an indkidnal died after xceiving gene theray): involving vascular endothelial growth factor (VEGF) at St. Etizabeth's Hospital. in L3oston.v Citing these deaths, nlany. physicians, researchers, and ethicists have insisted that tltere be a moratorium on gene therapy until tbc procedure has been perfected and the risks xnininizcd. 1x1 the meantime, they arguc, gcne theralfy should bc rcsenrcd only for terminal patic~ztsas a last resctrt. Aiter~~atively liposomes zrtighl- he saf'f.1-and more eEectiw vectors to deliver the crucial gerzes thzlrz virztscs, though diis has yet to be borne out by die research. "'' Pharmacogenomics mrould be an even more promising n~ethocl,since t l ~ etherapeutic drugs used would target the 1-eleval~tgenes more specificatly and woz~ldensure a more balanced interaction among genes, drug toecity, and n~etaboliism. But this is !Ear from being perfected as 1\7cfl.As it strtnds, gclle tbcrapy has sh~\vizsaxne success ill treating s ~ i a e people with hernophilia, SC:IL> (as in the cases of Ashal~tide Sdva and the FI-encl~babies), and !Eai~Ulialhyperchalesterole&. kirticularly significant is a rece1:zt stud11 siiokving that ~.mtwirdjgene therapy for henroplrilia A, zrsitzg plaslnids as Rctors, lias been stlccessfill itr pmdtlcing factorVXII, which is esse~ztialto blood clottir-rg.l 2 Also, 1-esear-chis well uncIer cwky to develop in utero gene therapy on second-trimestei- fetuses for alpha-thalassemia.13 For the nrajorit)i of monogenic and multifactorial diseases, howemr, gene therapy does not yet offer an et-fective treatment or cure.While it may offer of tbcse in the futurc, for n o ~ vgc~zetictestilzg and selective terini~z~ti~iz embryos with rnutatioizs t h ~ cause t severe gc~zeticdiscdses secins to bc the 111ost effective way to prevent tbc severe pain, sl.zEcring,and restricted lives these diseases entail,
Somatic-cell or gcrr.11-lil~tegcnetic i~~ai~ipulation of cmbrycjs may appear i1Iorc attractive than tcsti~zgand tcrr~Gnati~zg ther11, as well as x n ~ r eeffective than gene theram given at later stages of l1tr~xtat.1de\7eiopr11ent. Il1teuve~1tion at such an early stage could prft'17ent the disorder witbotlt fzavirlg to prevenweople front existitlg. If the rnanipulatior.1ir1\7olvc?d deler-ing a ~rtt~-tation at tlte germ line, then it 'uroulrt eliminate the mutation &orn the humall popul"tia", since it 'urorrld not be passect on to offsprixlg. Among other things, however, gernl-line genetic alteration may not be desirable from a11 evolutionary pcrsyective. Some genetic i ~ ~ u ~ i t i oare n slleccssary &or species to adapt to changing enviri311111ental conditions, and some gcnetic disorders involve alfeles that conkr a s-tzrvisal advai~tagc011 certain popuhtioizs. As noted earlier, the best example of this pheno~~tenon is the allele catlsiw sickle-cell ailernia, which pswides gl-eater ~-esistat:lceto xxtalaria for populations from a regiorz in Ahica. Alcerixlg a gene or gelles at the germ line to correct one disorder may- only lead to other disol-cters that could advei-sdy aEect people in many successive generations. This risk raises the question of trrhetlter we have a duty to prevent pasing 011 altcrcd genes with potentially harmful coi.rseyuciiccs to people who will exist in the distant f ~ ~ t u rIte . m,ry rccoi11merid avoiding germ-lir.1~ genetic xnaniyulatioi~altogether, which is supported 'by m70 related poir.~ts. First, people existing in the ft~ttlrer17ay be adversely affected by t l e consequences of a pmctice ta whicl~they did not consellt, Secorld, because of the co1nple.i ways in tvhich geiles interact, it w o d d be difficult to weigh the pl-obaltle health benefits of people in the present and near future generations against tlte probable ltealth b u r d e ~ ~tos people in the distant future, Because their interest in, and right to, not being h a m e d haw just as i11uch moral weight as those of the people who already exist or will exist in the near hturc, we wtjuld be 1\7cU-advised ta err on the side of caution, olzligated to dc3 so, 011 grotrnas of 11oi1in~3lefIxzdecd, we 1\7ould be i~~orally ice1:lce.Tlziswould meal1 pmhibititlg gerrn-lhe gezzetic manipulatior.1,or at it until h r t h e r research can provide a more favordhle least postp~szi~lg asscssrncnt of its safety ar~clefiicacyl" There is one ibrm of germ-line intervention, lto\vever, \vluch might not occasioi~tlte same concern as others. Oaplasnlic transplantation consists in introducing mitocltandria from younger women into the eggs of older wcti~~eri to increase thc success rate of IIVF infertility treatment. This is germ-li~leintcnrention because the I3NA h m the two mothers is passed down the xnatcrilal Iil~teto ftrturc generations, Bccause it is confii~tedto the xxritachondria, presuxxrably it would not change the DNA in the nucletxs of
an egg. But it is still not known 1%7bctbcrchanges to xnitochol~drialD N A ill ooplasllllc transplan~itios~ could effect cbangcs in nuclear 13NA. Bccatrse it is difiicult to assess the risk-bexlcfit ratio t7x uf-ltc in intcrve~ltioizs with eEects that are passed on to offspring, there may be biological reasotls against this far111 of genn-lii~einte~ventknas well. Mcrreover, it is questionable cvbether such an intervention could be called gene therapy; since it is questionable ~vhethert l ~ ecoiiditioii it is used to treat could appropriately be consirliered a disease, With respect to somatic-cell gcnc: therapy it is instrrrctivc" to cc>nsidcr further how it bears on the i~~etaphysical qtxestio~iof persal~afidentity and 011 moral qrxestions about bcsiefit, harm, eyualiy, and E~irncss,Recall the exarnple i r ~cliapter 2 about the boy tvitb I:)Mt:) who files a tort of wmt.~gf11l lik agiiinst his pnretzts, obstetriciarl, arldior gelletic counselor on the g1-ou1ld that they were ned&e':s tit1 assessillg the risk of-a child having the disease. There would f ~ t t rbe gmtrnnf for a claim or tort of wron$ul life, hokvever, if the child insisted that genetic i~~tervention other than testing and selectik~etermination of the embryo h m which be developed shotrld have occurred. For e x a ~ ~ ~ he l ~ lcould e , not claim thdt dcliverillg a normal copy of the dystrophi~igciie at tbc emlzrycjnic stage wtjuld have imde a significant dikFerc1icc bet\veen the life he actually h a and a better life he xxright have had. For at the drxre of this ix~tewexltion,there was no identifiat able person tvIio corrld have be~lefitedfront it. Ce~ieticintervei~dox~ nrch an early sragc of development of a h ~ ~ ~ norpnis1xr atl would have resulted in a completely djfferent set of biological m d psychological pi-operties belonging to a different person. So the cbild oiity corlld claim that the harm and wrc3iig were comnlitted by not terminating the genetically defective embryo Ercj111 ~vbichhe developed, not Izy gniliszg ta add a normal copy of the dystrophin genc, C;exie tbcrapy hzr a phyGcal disorder ilivolving soiaatic cells at soxne agc considerably after birth probdl->tywould xxremxz, solxre differer~cein biologiRut the cal ancf psychoiogical properrirs betitre a17d after the intewexsir,~~. difference likely tvotrd not be so great as to disrtrpt ps)ichofogical coilnect-cdnessand continuity and to deternune the identity of a distinct- person. We can a s s m e that the individlral already would have lived f i r a certain number of years and cvorrld haw a fairly cvell-tJeveloped biological and psychologcdl life. Although soiae inental and bodily propertics wc>uld change as a result of genctic intervention, there would bc enough siniilarity bctwecsi tbcse prcr)pcrtie&c&>reand after the tbcrapy to say that a child cured of rdableaccess to gcnetic tcchnolohy tbat could curc tbc discdse or control its syn~ptoms,but failed to avail theznselws of it, then pdinps the child could claim that her parerlts harrl-tecf her by defeatirlg tier interest it1 not experier~cinga disease that could be cured or corltx-olled through gclie therag?j~.Rut to the extent that the child already e i s t s with a life wortl~living, and tl~ather pareilts do not have control over and thus are not lrespollsible for the disease, this case would involve something other than the stalldard notion of .v\rrongfutlik. C3n tbc contrc>versial assumptioi~that second-trin~estcrfetuses arc persons, fetal gclie therapy could bc citbcr ail icleritity-dcterrrUning or idcntiv-pmserving harm of genetic intcrvcrition, W. French Anderso11 xnainbins clat "fetal gerle t h ~ r n p yoffers a power&] technology that could corrcct genetic diseases wliicll 11ow pmd~rccirrcversihle dall:rage befctre birth, so avoiding tlie need b r alternatiw techtliques such ns gat:nete dotlation, embryo selection, abortion, adoption, or non-part.nthood."1' The intake place after much cell diEerentiation alreaciy had octervention \\ro~~ld curred, But if the disease that is cured were severe to moderately sesiere, tbcrl correcting tbc genc that causecl. it 1\7ould rcsult in a sig~iificantlydifferent set of biologicdl and psychological properties a&cr birth. The psychological properties would be especially crucial, sillcc thcir nature a r ~ d contexlt could be quite diEeri.nt depending on whether one experienced a healthy life or a severely discasecf one. So whether the sarte or n diFerer~t person existed after tlie interventior.1 wotild tiirlge largely 0x1 the se\reriq of the disease in qrrestion. But a11 of this rests on the assumption that secanti-trimester ktuses are persons, an assumption that I do not make. All of the cases that I have disct~ssedthus f3.r involve pbysical diseases. More difficult ta assess would be gclie tbcrapy ta c~)rrcctor treat a mental disorder at any stagc of a perst311's life. Ikecei~tly,resea~hcrsreportecl. that tbey were able ta manipulate a genc iri the braills of mice and thcrcl-zy enharlcc their r n e r ~ ~ o rTliis y ' ~ suggests the possihiliv of restoring or even irrrproving cognitive fitrlctiaxl tllrotigl~xxtanipulatia~of the ar~alogousgene or genes in hrrn~ans.Quire apart fiom the obvious diflercnccs between mice. and hurrrans, it is slrnplistic tr:, tl~inktl~ata single gene or gene prociuct could control intc.lligence.This nrental capaciw is a fu~lctionof corn$ex interachns amoilg different genes, whose filr~ctionsin turn are atl fected by the interaction of human organisms with thcir social and can ;ifphysical environment. Still, subtle altcratioi-zsin brain biochc~~istry fect the naturc of and connection bcm~ccnxncntal states suclt. as bclicE~,intexltians, and errtotiox~sin which per%x&oocf co~~sists, Maniptxlatii2g J, gene
tbat p l a y ~ acrucial rcde in cogr~itionor emotion could dffect these mcntiil strttes and tbcrch3re alter personal iclientity. Aftl-rough geiietic intcrvcrition to treat xxrexltnl irxrpainxrexlt is not likely in die foreseeable f~itrrre,it is instr~~ctive to test our trtetnphysicni a d xnoral ii~ttritionsabout prsolzs by callsidering the respects in which gel~eticinteuvefltiot.1 could after one's cognititit. and enlotioilal states. Whether these intervtlntions preserved or changed the identit-)l of persoils m~oulddepend on the pLirpose of the intervention and the 11atul-t.of tbc 1ncnta1disorder i1-r qrxestion, If a perso11 were to lose previously nori-r~al i ~ ~ e n tfilnctioni~lg al as d result of a stroke, tbcrl the purpose of any gc~letic trcatrllent (fix examplc9dngiogencsis ta restore blood Now and ncurc3nal connections) on die relevz~ntregiax~sof his brain vvorrlci be to restare the level of mental f.ilr:lcrioi~i~~g 11e had before the strc3ke.Wlrile there wotrld be a gap it1 psychologic,\l connectedaess and colztinui~during the period when he uias experiencing the eRccts of the stroke, the illtervention ideally would restore canncctedness and continuity and hence his &?rmerself, O n the other hand, c o p i d v e or affecdve treatnlent for sonleonc with i~~oderatcly severe to severe mcntiil in~pairineritfro111 birth dac ta a gcnetic or chromosoiaal ai-zomaly; such as Fragilc X or I3ot;vil sprlirc>mc, wctuld be diniecli at raising thcir Icvcl of 1nenta1E~rnctioningta what is considered norrl-tal for persons. in each case, the gexletic iiltewentioi~would llave a tlierapezrtic mtioi ~the first ~ ~ a itfut e . it tvotrd have a diFerrnt impacr 0x1 person4 i d e i ~ t in case, the restorative eRcct of t11e intermntian wotrld reestablish the cannectio~lsbetween the ~lormalmental states tlte person had betbre the stroke with the nornlal states he cvould l~avefolfa~vingthe treatnlent, There 1\7ould be soiae disco~lrlcctcdnessbctwecn tbc time of tbc stroke and the time thc trcatr~~ent restored his ~ncntiilhnctioning.Yet this would be temporary ratbcr than perr-r~ancnt.l~rovidedt h ~ tbc t tclnporal gap 1\7as not too long, the intervexltiox~tvould restore his xmntal functioiling ancl identiq dncf would dpppriately he caltecf 'kcherray)..." It is ""r1er;1petrtic'7bt.cause it rnakes one ancl the SM-IC per5011 better off than before the strcke. 111 the secand case, t11e llature a ~ l dcolltent of the individual's nlental states would be radjcafly different before and after the gelled, interventioi~and thus would mean tl~atthe ortgl~lalperson wit11 the nlental disorder became d distillct person. Evcii if the mcmories of the i~idiviclual'spast exper i ~ ~ i cremainccli c intact after the therapy haw hc rcconstrrrctcd and ilitcgrated them illto d unifiecli set of mental states wctuld be inftucncecli by xxtore robust intelitioils drlcf desires,Tlle"i in turn tvodd xxrake his presex~t
strt te of coliscio~xsr~ess qtlalitiitively diiTere~itfrom w h t ~it x~cnuldhave been without the i~lterwiition,If this accoullt is correct, tbe11 the intcmeritiion c o d d not be thempetltic*For the person tvho prcsur~~ably be~lefitedfrola it no lox~gervvorxld cxist.Tfic t r e d t ~ ~ lfor e ~ the ~ t xxrer~taldisorder vvorrld alter the merltal states of the person to such a degree tbnt the iderltiq of the person with the disorder would be altered as well, The intervention in the stroke case could be defencied on grounds of a l to the norbeneficence and justice. By restoring the persour's m e ~ ~ tstates iml level o f h n c t i o ~ ~ ihe l ~ ghad bchre the stroke, we wc3uld be benefitil~tg bin1 by making hini bettcr off t h ~ nhe otbcnvise wtjuld have bee11 with its effects. Moreover, c ~ ) r r c c t i ~ the ~ gd y s f ~ n c t i owould ~ ~ restore adverse rnc~~tal his level of ft111ct-ioningwhere he had the satnc gelled opportunities as other people to trr~desrakeand complete p4ectl; within a life pian of tiis olvrl xxlakix~g.i 7 In contrast, if we cotlld delker a gene or genes into the brain of a sedisaMed illcJividual and dr-amat.icafly raise verely coglitively or aft"ecti~~ely her mental functionillg to a normal level, then we would not benefit tlris person, She x%7ouldnot bcriefit f'ro~athe intcrvention and be xnddc better off because the c h ~ n g cin her xnclital states x%7ouldlaedn a change ill identity. The interwiltion wtjuld not be therapeutic because it would not bc the case that one a r ~ dthe salne person was made better oiS: At- first bttrdi, the jz-tscice requirclncxfi would offer stronger rtlasons b r improvi~lgthe xxtentdly disabled person's cog~~itive or aEective capacities through generic nleans. A person should ltave oppartui~itiesfor prqects and acltiexments of wlticb she is depkved becarrse of' her mental disability, opportwities e q d to those of people with i~ormalmenta2 fu11ctioning.Yet the LJ.ifi>rence in ic"intit;)8 beG>re and after the intcrvention suggests that the justice rcqrxirernent would perti~i~l il1orc. to the level of cogriiitivc or aiFective CAp&ci@)r than to tbe particular persalls x%7bohave or lack these capacities to k~aryingdegrees. It tvotrd not nlatter nlordlly one nlight argue, that a particnllar mer1~2llydishled person becatnc a diffel-rnt. person folloxving ge11etic intemention, only that sornc person had the saxre level of ~xrental functi.oning and the same opportullities f i r achievement as other persons, This suggests a utilitarian argumellt for jtrstice, That is, raisitlg tlte aggregate level of mental tilnctioning across aU people matters morally more t h ~ nthe level of xnclital Eunctiionixlg of particular people. Yet, xvbcn we specify the bcrieficence and justice rcqrxirernents, we assuxnc tbat the cogt & persoli better offand incrcascs nitive or affective gclie therapy t h ~ xndkcs a person's opprturzities preserves tlie idcntiq of that satne persotl.We air11
ta m a k ~her bcttcr off than she was bchjrc the intcwention and thus provide her with the sa~ncopportur~itiesds other peaplc. O n l y by prcsenrillg her identiv c o d d the intervention be therapeutic.To insist 0x1 the tltifitnilriatl argrment that it does not rnatter who has these opportutlities, d y t . t ~ ~ r there are qportnnities, hils to respect the distinctivexless of persotls and unkrmines the coi~ceptsof "benefit" m d ""terapy."lU similar problem besets those who champion the use of implantablie brain chips to campellsate &?r melltal disabiliy. The arLwrnent fbr this intementioi~is bdscd on tbc principle of eqrxal oppartunity Yct dltcrilzg one's xncntali states to the paint of r ~ ~ a k i none g a diRerent persorl conflicts with egalitariarusm and underi-runes tbc dim of ~01111~ensation. BCII~&CCII~C and Justice prcsupp~se the idea of distinctiveilessr which it1 turn presupposes the identiv of one arid the sane irltiividtral persistitlg through time. Althotigi~the i~nperso~lal corxrpml'ivc: princjple provides so1ne support b r the utilitariat.1 argrlxrent &?rgenetically improving mental furlctioning, a more perstlasiw arglment would have to be advanced fbr ignoring the djstinctiveness of persoils embodied in the egdlitariall conception of Renefkence 2nd justice, If the egalitaria1.r conceptioi~of l>enc&tand opparttlnity is more piiausible than the ut2itarian conceptioi~,tbcr~there 111;ty be rcasorls for rrof usil~j; cog~iitivegene therapy on severely rncntally in~paircrl.il~tdivid~ials. These rcasoxls vvorxld be strorlgcr in the case of a rlloclerate to xxroderately severe cognitive disability, as in Down syx~clrorxre.Why try to raise the level of cogx1il.i~arld agective fitncticr~linffand change the idcl~tivof persotls if their nlental capacities are sufficient for happy and fulfiIIing lives? To be sui-e,we cotrld i n c ~ a s elifetime opportunities; but these could come at the expen" o f t b e identity of the person w l ~ opresumably m ~ u l dl~avethem. The upshot is thdt genetic ilztemcntioi~to i~r~prc>vc oi~e'sr~~ental functioning is tbcrapcutic when it rcfsforc2sone's functic?i~ixigta a previous normal level. But it is not theraperttic when it sig~zificdndyrd~iscsthe mental filnctioning of lifelong me11taZly impaired individudis to a 11ormaf level. Therof personal identiry, It1 the first case, the geapy presupposes prexrv'dtio~~ netic intervex~tionwould pr~"servcidendty; in the secoild case, it would alter identity. This point poses a chaaenge to the egalitarian idea of giving priority to the worse off, which further underscores some of the counterinttiitiw implications of cog~itivegene tbcrapy. Let us assulnc thdt an individual who has been cogrUtively ix~lpdiredfrom birth is 1\7cnrsc o E i n his life as whole than one who suddenly has !La;;lllc~i below the bdscti~~te of adct1uatc cogrUtivc i'iitlctionitlg due to a brain injtlry If gezletic intervetltion into the latter's
brain could restore him to tbc baselilic, and if the same sort of i ~ ~ t c ~ ~ ~ i t i did little to ilnprtjvc the condition of the former, then pric)rip tc) the vvorse-c->@inclividtnal could be cwerridderi. This is because die benefit in being restomd to the baseline of adequate xne~italfilnctioszi~lgis rnore xxrarally sigx~ifirantdian the xx~argixiall->enefitof arnelioratixig the coilditioxl of tl-te more sesierely affected individllal who cannot be brougl-tt up tc:, the baseline.The benefit in question pertains not to a specific time of ~ ) ~ ~ S Q I I S ' lives, the time at cvhtch the intervention migl-tt take place, but tc:, tl-teir lives 011 the whole. RecaU. tbat the 1\7orse-off priority p"ixiple says tbat a slnalfer bciiefit to tbc 1\7orse off has xnore xnoral weight than a larger benefit to tbc better okF. tfut if the aim of any farm of therdpy is to raise or restart" people to a baseline of adeqttate fiysical and xnentnl ftznctionir~g,tlierl the significance of rearhirig that levcf For the better off xxtay be enotrgh fctr their clair11 to treatment to outtveigh the claim of the worse offfor the same. It is morally pi-ekrahle to benefit the comparatiwty better oEa11d 1-estore or raise them to the baseline than to benefit the comparatively worse off if doing so only r~~ar@nalfy in~provcstheir collditioxl and Fads to raisc the111 to tbat critical level. Suppctse that the condition of the wcjrse off could be raised to the baseline of adeqrzate mental fiir'rctioi~ilig.Intuitively, this 1\70uld xnakc a stm~igcase t;or giving prioriv to them. But if the inrprovernetzt involved radical changes in the nature and coxitexit of their rllelital states, then they in fact would not be xx~adebetter off, sixice diey would not be the sdlrre persons afier the interve~~tion.This is quite t~nlilic:the case of storing the better-off stroke patient to the baseline, since brs mental states eRectively cvould be reconnected as a result of tl-te intervention and his identity wctuld be preserved. The coherence of and jusdticatioi~&or coglitive gene therapy hinge cr~lciallyon thc preservation of personal identity and whctbcr tbc purpose of the genetic iliterciendoi~is to restore or raisc peaple to a bnseli~~c of adeqrrate trterltal f.ilnctiotiing,
Access and Mlocation Issues Suppose that gene therapy mrere to became feasiMe fbr treating most physical a1111 ment;al disorders with a genetic cause. The Fact that these treatr1Ients wcjuld bc very expensive wt)uld gclleratc prcjblems of ec1ualif-r and gairncss, The main colzcern would bc 1\7ith equal aiEtrdablc access to the tcchnolog~.Thc issue of access also ~vouldaffect equal oppartuniv for a decent xxtininrttm l e d of wel-being, since having these oppnrttr~?itiespre-
strpgoscs adccjuate physical ancl. xncr~talfunctioning t h ~ the t tcchnolo&-)l. wctuld &warantee,There 1\7otrld be u~ieyualacccss to tbis tccbriolo~ybccatrse not e ' ~ ~ e v owould ~ ~ c be able ta afforcS it. This would be trx~fairbecause it would give an adv~t.lr;tgeto sorrle people over others who have an equal claim to treatment to meet an equal physical or lxtental need they have tltrorrgh no fiult of their okvn. O n e kvay to resolve this p h Z e m of fairness is to implement wltat Maxmrell Mehlman and jeErey tZotki11 cajl a "genetic lotter-)..""T3\.ving to its high cost, therapeutic gclietic tcchnolog~wc>uldbe coi~sidercda scarce i~~edical resource to be alfocated by lot w i t l ~ i linits ~ ~ t specified by tbc health caw system, Pcople 1\7bo needed t l ~ etccbrioloh~&or trcatmcnt of a xnedical condition would parf.icipate it1 the lottery on a valuntaq basis and would be selected randoxxrly for access to die tecfix-roloti,~, regardless of the abiliv to pay or social status. Mchtnan and Kotkin spell clrtt t l ~ eacivamages of suclt a lottery: It would a ~ ~ o i ~ i r n o dthe d t e assur1113tion tliat not dtf genetic \ervices coulcI be mdde d\iaiIdble to ever)ione. It xvould pernvt continued retedrch toward conquering gelletlc M ~ xvho could not otherwise agorcl them, access to gelletlc t.Iise&es. It xvould ~ I M people, tecliizi>log~es.W~tlim the Iottery, at least, tliere would be true equdity of oyportunit): By pcrxnltting wlxlx~ersto obtain access to whdtever genetic rervtces they w~shcd, ro jong as cIie service, xirere airail~bleIQ cIie O P ~ I I~nmkrt,tllc jotrery would avoid tllc or~erouscask of decidj~zgtllc technolcbgies to which pcol3fe rl-rould tte give11 access.^^
They go on to props" that such a lottery cotrid be financed by a progressiw illcome tax, which would transfer benefits from tlte ec0110nUcally advantagecl. to the economically disadvantaged. Alternatively, health beliefits of tbc better off (bcaltt?$B)could be taxed to strbsicliizc acccss to g c ~ ~ e t i c technologies for the worse off (ciiscascd).Although Mcblrnai~and BotEn do r ~ o tdifferentiak gene thertlpy kern g e ~ ~ e t enhar~centcnt ic widiin the htrtework of tlie lottery it shotdd be said that only a lottery didl: gave people access to trentxrtent but not enhancement would be rnordty defensible and fair.This is because scarce resources shotrld be allocated to meet people'e need for treatment, not their preferences &3r enhancement, given that needs have more moral trreight t h ~ npxferences. Fairness says that people's needs should be xnet in prcjportion ta their streligtb, ~vhictlis a functic311 of degree of 11ecd.And people tvho rcytlirc gene therapy to raise tbcln to the baseliiie ofadcqrxate fui~ctic>ning have more urgent ~ ~ e c than ds those tvho prefer genetic enhartcen-tet~tto raise tben:t above that le%7d.0 1 - r
grctunds of Oirness, tbcn, a genetic lottcry wc:,uld be deknsible only &or people whose diseases or disabilities gave thcrn a g c ~ ~ u i nneed c for treatxxrexlt, the need to be restored or raised to die baseline. Atlother aspect of fairness is the nunrher of people who tvodd sand to benefit frc3rn expex1Sjve gelletif techxdag.This slloltld be considered in coratrast to the number of people who stand to benefit from other, less expensive, treaments, As in the case of the lottery what motivates the qnestjun is the decisions within specified litlli~sto control health care need for allocatia~~ cc>sts.Here, hc:,\%7cvcr,the geiie~clottery xvc>uldnot be a viable modcl, since we would have to compare trcatrncnts invc>lvi~ig g e ~ ~ e t and i c nongenetic intcmentions. Health care currcndy c c > ~ ~ s t i t at ~sig~iificant t~s prcr)pc:,rdo~~ of U,S gross dornt.stic product (aro~ind14 %)I, and in o d e r to control inflation ofthis sector the cosa and bex~efit.slof gex~etict-I-eamentshave to be tveil;lt~ed agairzst the costs and benefits of other, Inore stan&rd, treatzTlents. Cal~siderthe number of people afflicted with monogenic disoders strch as Canavan disease (1 in 5,0OO), cystic fibrosis (1 in 2,500), L3ucltenne nluscular dystrophy (1 in. 3,5t)0 n~ales),a r ~ dTay-Sachs (1 in 3,60O).~"Rccausc of the interaction bettvecn thc vector carrying the gciie and thc targeted cells, thc effect of an i$ected geiie ~vcnulcibe only ternporary. lkcpextcd i~ijectionswc:,uld be needed. Rased 011 tbe moi~tblycost of enzynte-replacex11~1ittherary iirr Gaucher's disease, W can project that gene tlierdpy c o ~ ~ cost l d as mttch as $lC),OOO per xnox~tli.C:olnpare these iigtlres tvith the sigr~ificanttylarger ntlxxrber of people with coditions like hypertension,Type 2 diabetes, and asthma, wltich can be contx-ollec.1more effectively or prevented with less expensive treatments, Some of these treatments may coi~sistin conlpreltensivt. public healtlt and prenatal care programs. Ifwc 1\7erc ta strictly fiolfo~vthe idea of giving alzsctlute prioriv to tbe 1%7cnrseoff- tben we should allocate a larger perceiiGigc of lncdical resources tc:, special treatments fc3r cctiapc~rativcfyrare ger~cticdiseases, owing to their se'17erit-y:E-totvever, as argued earlier, prioricy to the worse of co~rtparatively off can be owrridder~if a substalltialIy larger nu~x~ber hetter-ofa' people could hetzefit frot~lless expensive tre;ltrnents, especially if gene therapy does not significantly imprave the conditioi~of the snlaller number with genetic diseases. Thus, with respect to the health of the general population, priority in tlte allocation of scarce medical rcscturccs should be given to s~indarci.fiorr~isof treatment ancl. prcvcntion over gciietic trca tmcnts. C3ne might argue tbat rescturcc prioriq should be given to genetic researcl1 0x1 possible genetic treatrnexlts far chronic mttltifactorid cor~tlitior~s
like hcart diseasc or calicer, instead of ~ a o l i ~ g c l iconditions. ic Again, the rationale wcjulcl be thdt a sulzstrtntially larger iitrlnbcr of people wotrld benefit front this order of prioriw and at mughly the same cost of tre,tting the In cancers, for cxart:~ple,rt:~osttrtzxlors involve a xxrutnted rare coi~clitiox~s. p53, or tltmor srxpprcssor, gene. Keplaciilg tlie gene tvith a ~ ~ o r m copy al migbt sqpl-ess the g r a ~ r t hof tumor cells, Gene therapy cotild control the rate of cell dkision a l ~ dt h e ~ b ypl-event tlte gromrth of ttlmors revonsiMe &>rall cal~cers." 111 Adititan, genctic research lnight lead to the developillent of ~ a c c i ~ i to e s prcvciit viral infections such as HIV-AILIS. With reic priority should be given ta research and treatspect to g c ~ ~ e t rcscdrcl~, illent t h ~ could t beliefit illore people affected by Inore pervasive but lcss sewre diseases over researcll rind treatr~retzttlidt could bellefit fewer people aBPcted by mrer hut rnore severe diseases. !)rim& ficie, priclriry should be giwil to meeting the most urgent ileeds of people with tlie rnost severe diseases. But this priority can he ovei-ridckn if the same a m o m t of resotirces could he wed to treat and sigiificantly benefit a substanrially larger number of people in terms of tlteir health,
Genetic: Enhancement: Gene tlierapy rnust he discingtiskd fro111 geiletic enllarlcen-~cs.lt. The first g and restorillg physical and is a11 iiltervention ainlecf at t r e a t i ~ ~disease xxrentnl f~zi~ctiax~s dncf capackies to &XIadequate baselir-zc.The second is an interventrian aimed at imprwing tilncri.ons and capxities that aixady are adequae. Gei~eticenhancement augments tilnctiours and capacities "that cvithout ix-rterventionwotrld be considered endrely narnial,"24 Its gcxl is to ""ai~~l~lify 'normal' gcr~csin order to make tbeln b c t t ~ r . "In ~ ch'jptcr I , I cited Normaii 13anicls's definitions of health and diseasc as well as what st carc entailed.This i~ivc)lvedmaiiitaiiiing or rcstortbc notic>lio f j ~ ~health ir-zg xxrerltal ancl physical f~ii~ctions a t or to izorxxtal levels, wllicl~\'ii;~sxleccssary to ensure fair equaliv of n p p o a u i ~ for i ~ all citizet:ls, frlsofar as this aim defit~estlie go81 of- medicirle, genetic et:lllailcezx~entMfs oritside this g-r>21.F r r r t h e r m o ~insocar ~ as this type of intcrvel~tiol~ is not part of the g-r>d of meiiiicii~eand has no place in a Just health care syswm, there are no medical or moral Rasons fbr genetically enhancing normal htiman h n c tiolis and capacities. Somc have argwcd that it is ilistakcn to think that a clcar liiic of dernarcatic>li can bc drawl1 bctweeli treatment and ei~h~jncemcnt, sincc certain hrnm of et:lhailcezl-lentare ernployed to pre\rent disease. Lercjy Wialters a i d
J d i e (;age Palr~~er refer to the i~nmunesystem as an example to make this paint: 1x1 current rntdtcal practrce, the best examl31e of a xv~delyaccepted health-related physical ex~haxlcententis irnxnunlz;iriczn ag'1ix.tst tnfectxom diseaw, m7xth~mrr~unizations dgd1nt;t diseases like polio and hcpdtxtis 13, what we are \aylng is xn et:I;cr,""Tfre xlllrnune \)."stemthat \VC ~nhcrlted& o ~our r ~ pdrcnb may not be ddequate to wdrd otZ-certain viruses if we are expored to them."TThercforc, we will enIia~lcetlie capabilities of our Irtimune syrtelll tny prinling ~t tc:, figlit against these virures. against particular di\ertre\, it xvoutd From the currerlt practice of ~rtimu~-t~zations seem to tte only a s ~ l t ~step l l to try to el~Ei~nce tile general fux~cticznof the ixntltunc systetrl by generic nteaxa, . . . In our vie\% tile gel~eticenlrancetxlenc ofthe irnt~tune systetrl would be rnorally Justxfiable rf this kind of enhaxlcement ,~sststedin preventixlg dlsedse and d ~ d not t'mse c?rfIiettxngh a r m to the peopk treated by the t e c h n i c j ~ e . ~
Ncvertbeless, because tbc goal of the technique wc3uld bc to prevent disease, it xvcntxld not, strictly speaking, be erib~nceiacnt,at least not in tcrrns of the definitions give11 at thc outset of this section, C;~ricticallyintcrw~iixlgill the imm~11esystem as described by Waltcrs and Palmer is a lrteatls of lrtaintaining it i r ~proper workirlg order so that it tvill be better able to ward off pathnge~lsposing a threat to the org;irlistn as a whole. Thus, it is rllisleading to call this ixltewexltion "er~11zlr~cexrter~t~"Wher~ tve consicjer what is normal human fui~ct-ioning, we refer to the whole lttllllan organism consisting of immutle, endocrine, nervous, car~lio~ascdar, and other systcms, not to these systenls understood as isolated parts. The norlml f u n c t i ~ ~ l iill ~ ~qlxcsti~ll tg here pertains to the ability of thc imr-r~unc: systcln to protect thc organism from infectious agcllts and tbus ensure its survival, Any prcvei~tivegenetic intcrvcrltiorl in this systcrn would bc desigr~edto lrzainbil-1the norrrtd functions of tilt: orgallis1:ll,not to ft7stoft7 them or rnisr them above tfte norrrt. It wotild be rlether therapy nor ellhancerrlclit but instead a forxrt of rnaiutenancc. Therefore, the allegecl ambiLwity surrounding what Waiters and t'ali~ler calf "cnl~ancing"the imnlune systenl does not irnyugx~the distinction betlveen treatnlent and enl~ancement. If enhance~aentcould make adecluatcly functionirlg bodily systelns functic>i~ cmn better, tbcrl prcst~mablblythere xvcntrld be no linxit to the extent to which bociily functions call be enhanced. Yet, beycj11d a certain point, l~eightetledi ~ n ~ n t r nsetzsitivi.cy e to ir~fectiousagellts can lead to an
c3verl-y aggressive rcsyonse, resulting iii autaini~i~unc discdse that c211 darnage healthy cells, tissucs, and orgdns. 111&ct, there would be a limit to the bexleficial eEects of genetic ir-zterve~~tion in die irrtxxrunc systclxr, a limit bey o ~ i dwhich the eqtrilibritrxn between huntoral 2nd cdttlar resporlse xxrcchanisrrts would be distrxrbed.27 If any intei-ventio~~ ensured tl~atthe equdibi-ium of the in~munesystem tvas maintained in proper mrarhng order, then it would be inap17mpriate to consider it as a form of enhanceMlCuzt. Tc3 further support the trcat~11eiit-ci1h~zncc1i1entdistiiiction, co~lsidcra no~~genctic intcmcntion, the use of ;L bisph~sphondtcsuch as alendrclnate sodium. Its purpose is to prcve~itpc>stme~i~pausal wc>~neii frcxn developiiig osteoporosis, or to rebuild bone ixi woxrreri or xxrexl who already have osteoporosis. Sornc nlight claim that, because it car1 increase bone densiq, it is a b r t n of crillatictzzrterlt-.But its xrrore general purpose is to prewnt holle fractures a d tltrrs maltitdin pmper bone function so that one can have nornlal mobiliq and avoid the rnorbicliq resuldtlg from factt~res.In terms of the functi.oning of the entire organism, therefort., it would be more acthe use of bisphosphondtcs as prcvendoi~,treatment, or curate to co~~siclier x~~ai~itendnce rather th'z~~ enhancement. Saine might raise a different question, Suppose t h ~ the t parents of child xrtttch shorter thd1-1 the riorlrr for his age persuaded a pllysiciar.1 to give him growth h o r r ~ ~ oinjectiofls ~le in order to ir~cl-easehis height. Sup-pose tiirther that the child's s"nortl:lc"sswas rmt dlle to all iatmgellic cause, sucl~as mdiation to treat a brain tunnor. Would this be treatnlent or enhancenlent? The questioi~that should be asked regardix-rg tl~isissue is not whether the chdd's heigbt is normal f i r his age group, Rather, the quest i o i ~should be 1%7hctbcrhis c011diti011 implies somethixig less than norri~al physical furictioni~ig,such that he wctuld have fc~vcropportl-ti~i tics EOr achievement and a decent mi~iiniulnlevel of ~l7ell-beingcwcr his lifctin~e. 1:)irnitizrti-rd.estature alone does not riecessarily imply thal- one5 functionirlg is or will be so lilnited as to restrict otie's oppofitluGties for nchimrnent. Clf cotrrse, being short rI-Iight limit orieS opportunities if one warited to became a professional basktball player. But most of us ai-e quite flexible when it comes to firnlulating and carrying out life plans. Wobert Reicb, the trc.asul-).secretary in President Cfinton'c first administratim, is Just one example of how onc call achieve very much in life despite dinlinutivc strtturc. If a child's stature Bgnificantly linlitccli his filnctioi~i~ig and opgartunities, then grc>\%7th-hor111oncixijcctions should be co~~sidered therapeu-
tic treatment. If his stature were not so linGti~ig,then the iijections should be co~lsidcrederiba~~ccmcnt. Adlxrittedy, there is gray area near the baselirie of adequate fi~nctitrriitig wllerc it xnay be difiicult to tlislingiish between trcatrnent and enhancexxrent. Accordil~gly,we should cosistreze the bdseSixle looseSy or thickly enough to allow f i r some millor deviation above or below what would be considered normal functiming. An intervention &?r a condition near the baseline that 'vlrould raise one's hnctioning clearly above the critical level should bc considered a11 enhanceiaent. Ail intervention for a condition i ~ ~ a k i none's g functioning gall clearly below the baseline, with tbc aini of rriisilzg one's functiox~ingta tbc critical level, should bc co11siJerc.d a treatxxrent. For example, an ,"itlllete with a Ilez2?ioRjOl"ti11level slightiy below the 11olrm for people his age and r~~ildly arientic xxray wtzt to raise that level sigr-tifica~itlyin order to be xnore corrtpetitive in his sport-TO the extent that krs actual Itemaglol-tin level does not interfere with his ordinary physical &ncti.oning, an intcrvel~nonto significantly raise that level w u l d he an instance of enhancement, In contrast, for a cltild cvlto has severe th'jlaswrnia and severe anernia, with the risk of l>oi~cabnormalities a i d heart Failure, an intervention to correct the disorder 1\7ould be an instailcc of treatment. The xnain xnornl concern about getzetic enhancenretzt of physicaf a ~ l d xxrental, trnits is that it tvotrd give so~xrepeople a11 unfair acivamage over others with respect to colnpetitivtl: goods like beauty, sociahiliv*anci intelligence. Unlike the c a g ~ i t k e l ycjjsabled illdivitlnal considered earlier, we can assunle tltat their mental states would not be so diEerent a ~ that ~ dt1te.y would retail1 their identity. Enha~Icen~ent wotrld be u ~ ~ f abecause ir only tbose who could affi>rdtbc t e c h n o l ~ ~wc3uld y hdve access tc) it, and m a q peoplc are 6nancialfy 1\7orsc off tf-rc3nothers through no Fault of their own, IlzsoFar as the passcssioil of these gc~odsgives some people a11 advax~tagc over others in careers, incon-tc, and soci;ri status, tlie competitive ndtu1-F:of these goocls suggests that diere would be xio lirnit to the beliefits that irnprovernetzts to physical and rnetztnl, capacities wotlld yield to those fortrrnate enough to avail themselws of the technoloLWThisis altogether different from the example of immune-system enhancement, There would be marginal value in the degree. of con~petitiwacfvantage that no di~~inislting oize could h ~ v cewer others 63r the sctcial goods iii yucsdox~and prcstrmably no limit ta the value of enhancing the pl~ysicaland xnerital capacities tbat would give oize tbis advax~tagc.Not h'jvi11g access to the tcchilolog~ that could r~~anipuiate generic traits in such a way as to enlla~icethese ca-
pacities wctuld put 0 1 1 ~at a cotnpetitive disadvantage relative tc:, others who wt:,uld h ~ v eaccess to it. Advancir~gan arglzxlent similar to the o1le trsecf by those who reject the treatlxrent-cnhn~zcexxtez~t distinctiojt~,one xxright hold that coxxrpctitive goods collap" ethe categorical distinctiotl b e m e n correctitlg deficient capacities and inlpmving 110rnnal ones. This is because con~petitiwgoods are contixluous, coming in degrt.esl and therefore the capcities that enable one to acheve these gc3ods cannot be thou&t of as either normal or deficient." Ncvertheless, ta the extent tbat any for111 ofgcnedc intcrve~itiionis i~~otivated Izy the medical and 111oral aim ta crialzle peaplc ta have adcqrrdte xnciitiil and physical hnctionixig and gair eqttaliy of opportunitr)r &or a decent rninimu~nlevel of well-being, the goods in qtlestior.1 are lot c m prtitirv but i~irsk.In other wrcfs, the aim of atly xxtedicdf interventio~lby gez~eticmearls is to rnake people better off tlinn they tvel-tl befare by raising or I-estoring them to an absolute baseline of normal physical and mental firnctioning, not to make them compai-ativejy better off than others. Conlyetitive gc3ods above the baseline. n1ay be cantinrtous; but the basic goods t h ~ ellable t sctiaeonc: ta reach or rclnai~~t at tbe baseline arc not. Given tbat these t ~ : types , of goo&s are disti~zct,and thdt they rcst~lt6c31n tbc distinct aims and practices o f enhL3ncemcntand treatment, we can ;iffirm tlidt enhal-lcement nrld trcatrnent can nncf should be treated sepmtely We can trphofci the cfdirxt that the ptlrpose of any ge~leticintervention shotlid be to treat people's abnormal tiinctions a ~ l drestore them to a nor-mal level, not to enhance those tirnctioi~sthat already are normal. As I have nlentioned, genetic enhancenlent t h t gave some people an advanage over others in possessixlg competitive goocls wotrld entail. cansiderat?le trnFair~iess.A likely scendric:, wt:,uld be onc in w h c h parentqzaicl ta use experisive gcnctic tccbiiolohy to raise the cognitive alzility or in?prcwc the physical bcatxty of their chddrcii. This wt:,uld give them an ad\rantage over odier childre11 with w h o r ~they ~ vvorxld colnpete for cdrrcation, careers, and incorxre. Chidren of parent-s d i n c o d d not affad to pay ii>r tlie t e c h ~ l o l o ~tvotlld q be at n co~~~parntive disaclv'dx~tage.Even if the goods in question fell above the normal funcri.onal baseline, one still could maintain that such an advantage m ~ u l dbe u~~fiair. It would depend on people's aability to pay, anif inequalities in income are unkir to tlte extent that tbcy result Em~nsome Factors bcyc311d people's control. We could not appeal ta the notioi~of a genctic lottery ta rcsctlve the problcin of ~airncssregarding gcnctlc enhancc~nent.For, as I a r g s d in the g negcfs tlian last section, such n lottery is better stlited to r ~ ~ e e t i npeoglek
tbcir prcfcrc~iccs,and e~~h~jncc~nerits correspond to people's prefcrenccs. Morccjvcr, x lottery might only cmcerbatc the problcin by rcink>rcing the perceptioti of unfairness, depc~idingon how losers in the lottery ititerpreted tlie fact tlidt others won merely as a resellt of a ratidorn selection. ne mlggestion b r resd~*7iilgthe fairness problenr (short of banning the use of tlte technolof;), altogether) 'u~ulcibe to nrake genetic enhancement available to all. C)f course, how this system could be fi~lancedis a qucstrian that admits of na easy answer. But the more important substantive point is tbat t~nivcrsdlaccess ta gcsiedc enhancc~nentwc~uldnot bc a solution. 111deed, the upshot of such access wcjtrlci provide x reas011 for prohibiting it. t Universal xvailabiliy of gcnctic enhanccsner~twcttrld xncall t h ~ Inany calnpetitive goads sorxre people llad over othen w o d d be cariceled out collectiwI!I, The idea of a corxrpelicive d d ~ ~ n b ggmdnaliy e mot-tld erode, arid tliere mould be m m equality arnong people in their possessioti of goods. There cvodd not be complete equality ha~rever,Diftocring paxntal attitudes tomr:~ud such goods as education could mean diEei-ences itl the extent to which cognitive enhancenlent was utrlrzcd. Some parents wotrld be rllorc selective than othcrs in sendillg their children to bcttcr schools or arrai~gingfor private tutors. So, there still wcjtrlcf. be soiae inct1tralit.)8in the gci~eratoutcome of the enhancclacnt. But quite apart frc~mthis, the pmccss of neutralizing colrtpetitive goads could end up being self-dekating on a collective l e d . 2 9 More specificd1y or.= prohc~hieside-eEect of boosting chifdre~i'strrerltal capdciq on a broad scale mould be sorxre br~ii7t damage resulting in cognitive and affectiw impairment in same of the children cvlto received the genetic enhancenlent,The net social cost of using the technolo'q 'u~ouldout~veighm y social advantage of everpne using it. If no onc: is ~nadcbetter off than othcrs in tbcir possession of social gc~ods,but sosnc people arc lnadc 1\7orse o Et h ~ ntbcy were bcfc~ei ~ terins i of tl~eirrl~entalh n c t i o ~ ~ i n then g , the net social disadvdn~igewcjtrld pro~*7ic5ed reason for prohibiting coflective ge~ieticerillaricetmxit. There i s dnotller xxraral aspect of cxihancerrlclit that sharrlc3 be considered. I have xxrdintaitled that i~lecftrdZiEiesabove the baseline of xlorr~rnl yltysical anif nrental filnctiol~ingare of no great moral inlportmce m d may be neutral on the question of fairness. Nthaugb equalicy and birness are closely related, one does not necessarily imply the otlter. Agaitl, fairness pertains to meeting people's nccds. Chce thesc nccds have been met, inecluditics in the posa"Scx~06 goods relating tc:, prcfcrenccs arc: not so rl~orallysig~ifificdnt.Thus, if the idea of an absolute baseline inll~licst h ~ t people9$basic physical arld mental needs have been trtetl rind if people wlm
arc comparatively better or 1\7orse off than others all have functioi~ingat or above the baselil~te,tben any ilieqt~aliticsin functioi~ingalzcwe this level shotrid not Ixratter very rnuch trtorally If this is plausible, tllerl it seetxts to follow that h e r e tvould be x-rothix~gtinfair and hence x~othingxxrarally objectionable about e~lhancernentsthat made some people better off than others above the. basetine, Nevei-tlteless,this cotrld undernline our belief in the imporal~ceof the t-irrrdamenal equalit). ofaU people, regardless of how well off they are in absolute terms, Equality is one of the social bases of and stability.-?"Wcjwil~tg self-respect, which is essential for social hL3rl~~oi~y inct1ualitics 111 access to and posesion of coiapetitivc gc~odsat any level of functioning or welfdre xnight eroclc this basis and tbc idcas of harmorzy and stability that rest on it, Although it would be diffjctrlt to rllcasrrrc",this type of social cost res~tlringh r n gerietic enhancen-~ultcotlld constitute atlother reasoll fizr prohibiting it, Yet, stlppose that we could n~anipulatecei-tail1 genes to enhance our noncompetitivz virtrrous traits, suclt as altruism, generosity and compassion." SSrxrely tl~csewould c ~ i ~ t r i bto ~ taestable, 1\7cU-~rdcrccl.sctcicty and preserve the principle of fiair cqrxdlity of opportuniy. Nc~tbi~ig in tbis program 1\7otrld be incompatible with the goal of rncdicil~teas thc preve~ition and tredtmcnt of disease. Rut it wc~uldthreaten the il~tdivicluala u t o i ~ o i ~ ~ y esse~ltialto us as moral agei~tswho can be candidates far praise and blairre, p~r~~lishrnent and rc"~varc3.VVhntcoizfers rnomi wortl~011 ollr actions, and inas agellts, is our capaciv to clrltivate certain disposirio~ls deed on otrrsel~*7es leading tr:, actions, This cultivation i~~volves the exercise of practical reason and a process of critical sell'-ref3ecti.o~w h e ~ l ycve modij); elinlinate, or reinforce dispositions and thereby come to identity with tltem as our own. Autonomy consists precisely in this process of reflection and idelitif"1catiorz. It is the capacity. for rcAcctive self-control that enables us ta take responsia l and tbc actioi~sthdt iss~refrom them. C;ivc~ithe bility for our m c ~ ~ tstrttes irnpo"t"x"ce of atrtonol-rty, it tvorrld be prefernble to have fewer vlrtuorrs dispositioi~sthat we cd1-1itjetlti@ w i t l ~ our s own than to b m ~xtorevirtuous dispositicri~sirnplalted in us t h m u g l ~genetic enhancen-1e11t.These cvould threaten tr:, undernline otrr moral agency because they- would derive from an external some.""E-vei~ if oar genes could hc manipulated in such a cwky that our behavior always conformed to an algorithm for the i~~orally correct course of action in every situation, it is u~~likcly that we wctuld want it. Most of trs wc~uldrather xnake. autoii~iaouschoices that turned out not ta lead to the best courses of action. This is bccduse of the itltri~lsicimportance of auto~lornya d the moral gro~vthand maturiry that
c0111e xvith xnakng our own choices under u n c c r t a i i i ~The dispositio~~s with xvhich we coxne to icleriti6, iinperfect as they 111;ty be, arc what make zrs autorlomotrs and responsible ~ztoralagults. Enhalcii~gthese ~ztex~tnl states through artificial rllcalls external to our own exercise of practical reasoil and our own process of i d e n C j f a i o would ~lii~dertnine w r autorlonly by nlakiltg then1 alien to us, In sum, there are four reasons why gei~eticenhancement wotrld be morally objectionable. First, it mrould give an m h i r advmtage to some people over others bccause soiae wt:,tald be alzle to pay &or expensive enh~ncerneritprcjcedurcs while others wcmld not. Seconcli, if WC tried to rcinedy tbc first prol-zlem by xnak;ing gcnctic crihai~ccinenttrnirrersdlly accessible, tllexl it would be coltectively self-&featin% Although xxttrch cornpetitiw tt~~fairness at tlie individual le'17el wotild be cancdecf out at the collective level, there would he the zrndcceptnblc social cost of soirte people suffering h m adverse cognitive or emotianal effects of the enhancement. Third, inequalities zclsulting from enhancementf; above the baseline of norcotild threaten to undermine the mal pltysical and mental f~~nctioning coi~victionin tbc fundannen~rlin~p(:,rtanccof eytiajtity as O ~ of C the bases of self-respect, and in turn social sctli&rity and stabiliy. Fourth, cribar~ceiIIent ofii~i~cornpetitive disp(:,sitionswould tbrcatc~lto undermine the autonoiny and moral ageilcy essential tn us as persons.
Negative and Positive Eugenics: Is There a Slippery Slope? The two &?rms of genetic iintcrventioi~that 1 have been discussing in this cbap~"rou1d be cltai-acterizecl as eugenics, defined as "tlte use of sciei~ce applied tc:, the qualitative and yudntitativc improvement of the human Eugenics" is aliaost universally regarded as a dirty xvcnrd, owgenomc. ing largcly to its association xvith the evil practice of bctinan experinlentation in Nazi Gertm~lyancl the widesprtldd sterilizntioi~of certain groups of people in the United States and Candna, earlier in the fivc~itiethcentury'J One cannot help but attribute sonle eugenic aspects to genethical questions about the number and sort of people who should exist, Bilt there is a br-oader conception of eugenics (literally ""good creation" in Greek) that need not have the repugrxant connotation of improvillg the human species. The purpose of terminating a11 embryo with a mutatirrn that xvould cause a disease, or of givkg gclie therapy to soiaeonc xvith a disease, is not to ixnprove the hurllal;~genomc or the human species hltt instead to pre1 9 1 3 44
vent or treat discdsc in idcntifial>le peaplc. The ptlrpax is not the in~perso~ldlc3nc of increasing the qtiantity and quality of types of experic~iccs, hut ir~steadthe pcrson-nfTecting one of prevetlring harm to and be~lehtitlg people who have or tvould have to experkizce the sylnptot-ns associated with severe disease. Accordi11gly,while reraix~itlgn bmaci gerzethical focus, cve sl~oulddistinguish betlveen positive and negative eugenics, The first type is motivated by the perfectionist ideal of impraving the human spehes, w h e ~ a sthe second is motivated by the beneficent ideal of health promotion through disease prevention and treatment. Tc3 tbc exterit that t aim of tbc aim of gcne tbcrapy is to prcvcrlt or control disease, and t h ~ the genctic enhL3nceiaentis to iniprc~vepeople's ;already normal traits and CApacihes, tliese two h n ~ of s ge~zeticintervetzticztl correspond to ~zegative arld poGtive forfns of ertpnics. F o r m of- eugezzics not itl'i7olvi11g direct gellcttic it-rtervention have been practiced since antiquity In nato's Rtyuhllr and L a u ~ sfii~ example, an ideal society would encourage "juciicious nlatings," meaning that mating bet~veenmembers of the rtiling and mexantile classes would be discouraged. Chly those peaplc most likely to produce t b "best" ~ ofEspring were encouragccl. to mate, especially 1\7ithin the ruling class,This cxalaplc of yositivc ettgenics is i~~orally ol>jectionable bccdusc it iilvolves discrinination on the basis of social class, By tht. sarx~etoken, however, ninny people today select xxrates wit11 whorx~they believe they will have chiIdrer.1 tvitll favorable pliysical rind intellectual traits, giviclg them a contpctitive ndvantctge over others for social goods.This is also a version of positive e u ~ n i c seven , thotrgh it does not involve genetic intervt.ntioir. Nor cvould nlost people acknokvledge it as sucl~. Sclcctiizg a specific mate ill ordcr to have children with specific traits and capacities by itself is not 111oraUy objectioi~alzleta the exterit thdt it is 110t part of a state-sponsored program, dc~csnot il~volveany coercioi~,and does not give an w16air advantage to sorne people over othcrs in fiavirlg chidren, Although this practice rxlay seen1 o)?jectioiz,lble to sornc because it is trtori~atedto have chiIdretz wit11 trrorl. than just n o r r d piysical ancl mental tirirctioiring, it could be deknded on moral grounds. For, in the . cvhich natural process of reproduction, it callnot be p ~ d i c t e dprecisely traits a child wiU h a w given the parents' genetic pr-ofile alone. Epigenesis and tbc incoi~~~>lctc penctrarlcc of geiioty~>eslargely account for this trncertai1zt)l. O n the other hand, gciietically i l ~ t c r w ~ ~ ito i l gp r ~ d u ca ~child with specific traits and cdpacitics night be objectionable because it could largely shape the chiIdS fate and cast doubt on her atltotlorny nnd mspotl-
sibility fix the gi~odshe achieves ill hcr life. All example of negative eugenics without gcriedc intcnrcntion would be if a person from one race rnarried a person frc3t~1anotller race with the interltiox~of not passing con any deletcriorxs r~ltr~ltions arlcl diseases to ORsprixlg. AecorcSiltig to the "consanpiir-zit)j.coefficier~t,"the rnore similar the g ~ ~ " n o ~af p etwo s people are, the mare likely tltey kvdl produce offspring with deleteriatrs genes ca~xsixlga r predisposing them tr:, certait~diseases. Conversely3tlte mare diEerent the two genoty-pes are, the less likly they will pass on dclctcrious genes tc:, their offspring. Thus, if a C:ritucasian wtjman were to I X ~ T T )an ~ Asia11 illal.r,and b ~ t believed b that thelr- diKercnt genovpeHlleant a higher prc:,bal>ility of p'tssing on ~ ~ o r r ngenes al to their children, then they could be said to practice negiltive etlgenics,'%'lzeywould want to exlsure h a t any of their childx-e~idid rlot have a high risk of inheriting ~ r t t ~ ~ l t i othat n s would likely result it1 disease. tinlike the example of positive eugenics given above, there wotrld be l~othitlgnlorally ab~ectianaMe about this practi.ce because the pare11ts"intention would be to reduce the risk of disease in tlteir c h i l d ~ nand tltereby preveilt tltern h r n harm. Similar rcasoliixig applies to thc case of ;L ralzbi who advises a man and witman who arc C3rtbodox Ashkcliazi Jews and carriers of the Tay-Sachs allelc not to marry, or else not to have children, Prc>vidcd that tbc ralzbi's advice was nsot coercive and the couple made a voluntary, irifirtrrned decifor~rzof ~legi~tive ertger~ics.Xt sion, this too vvorrld be a orally defe$:~~sfbXe wotxld aim at peverltirlg harm by elimirinting the risk of llnvirlg a child with Tay-Saclts cltisease, It might be nlore apl~mpriateto caU tkrs last preventive strateu a form af rrt~drctlics,a beneficial manipulation of environmental factors to premrrt or treat discases.""Rctter education and nutritiol~wc~uldbe Inore effective ways of acl~icvilzgthis gi~dlill tbe general population, Still, gclietic testil~tg &or the presence of 1~tl~itioi.r~ i ~ ~ a k npeople g susceptible to vdrious diseases can be parr of a genernl euphentcs prograrll. Krro~vingthe s)..mptolrts arld ge~leticcatrse of a disease rmy etzdbi,e us to devise trcaaxzetzts that can contm'i its syrnptotns, Again, the best-kxlo~vndisorcjer frttirzg this description is PMU. Restricting an aRected child's dietary intake of phenylalanine can neutralize the harnlftxl eEects af tltis disorder and ensure a life without severe nlental re"e"tardation.In addition, people wit11 sickle.-cell anemia can avoid morbicliq by takng perucillin, and tbosc with alphLj-thLjlassenrua may be cured by borze-m,rrrcj\v transplantation. The social environment can play an inipartant role as well. I already have poiiit~dout thdt the severiy of schiznphrerlia can be contrcrlled to sorrze extent: by hnzilial and social
support of thasc who have tbe disorder. 13espitc diiTerc~iccsof defi~~ition, ulti~natclythe gcxl of both negative eugenics and eupher~icsis tbe sxrw---healtb pmrrtc3tion throzlgi~p r e v e ~ i t i oarzd ~ ~ tre,ttmerzt of disease. As in the distirzctio~lbetween gene therapy arld ge~zeticenhnncetl-tent, the main distinctio~zbctween neg~tiveand positive etlgerzics is that the first is based on the pritlciple of beneficence anif the second on the principle of perkctionism. In gene therapy, the goal is to benefit people by restoring or raisillg them to adeqrrate pksical and mental iirnctioi~ingand givi~zgthem opltarttai1ities to achieve a deccnt ~~Gninlurn level of fifctinle well-bci~zg.In genetic enhancc~llent,the goat, is to give additional benefits ta people who already have adeqtlate fu~icticoi~ing, perfccti~igtheir traits arzd capadties and givil-lg thetl-t arz a d ~ l - ~ zover ~ ~ gothers c in competing for social goods. In the first case, we arc trtorally obligated to create people ulit/?~>z.tt certairz traits, or to rerrlovd" diese traits once they exist, Rut we are obligtted to do this only if the. traits in question cause severe disease a t ~ d disability and severely restrict people's opportunities. In the second case, cve are nloraXly obligated to create people wit)? certain traits, or to add t b e ~ nto exisd~lgpeople i~zorder to raise tl~eirfu~icdoi~ing and increase tbcir opparttailities above thc norm for persoils. Rut how can we bc so sure t h ~ n~gative t eugeIUcs will I I O ~evolve into positive cugcIUcs? Is there not a dippery dope here? [%ernarc2Williairts notes that the slil~pex7~-slope ar~tn-terzt"is ofiexz applied to rnatters of ~neclicslpactice. If X it; nlloxved, the argumerzt goes, then there will be a nattxral pr-ogression to Y"(>Far pmsent purposes, we can take X to represent gene tl~crapyand negdtit~eeugenics, andY to represent genetic enhancement and positjve eugenics,The natural pmffression from X , with the ostensible aim of raising or restoring peoplevsfunctioni~zg ta a normal level, toY leads to the ""horrible result" of positive eugc~~ics at the bottom of the dopc,3' P~sutnablywhat rrlakes the etlgenic slope slippery is ttlnt ollce we get otz the negative side, we caxztzot get oEand fall on to the positive side.Tlze poirzt of the nrgirrlent is that we shouM not get on the slope to begin with. Negatives etlgcllics is not ~xtorallyjustifiable xzd should not be practi.ced, because it inevitalrly leads to the positive eugenics and the violatiours of bumm value and dig~it)ithat it entails, Many invoke the slippery-slope argunlent to reject contr-oversial practices i~zbi0tech1101c)g~.Bat if the argui~~ent is to serve as a grc~undfor reJecd~lgtbcse prdcticeh tbe11 it xnust be sound.Trctc prci?lises must entail the ~ O ~ I C ~ U Let S~O . USI Inc3\\7 examinc: thc logical k ~ r i nof thc arLwment as it is i c s detertrline whether it is sotr~ld. applied to e ~ ~ g e ~ larzd
Thcrc arc thrcc different species of tbc slippev-slope arhwrlient: conceptual-rclatisig ta vabwcness of tcrr~is;precedcntial-rclati~zg to the need to treat sirr~ilarcases coiisistex~tly;arlcl causal-reladng to the avoidax~ceof the acrions &at will initiate a seqtrerlce of e\rent-s leaciing to m tzndec;irabie resrrlt," The classic or generic arkmment, the one most oilen advanced in &scussions of biot~chnalo~q, i~lcltidesaspects of all three species. First, defenders of the slippery-slol~earglment exploit any vaweness in the defirution of terms, They claim that the diRemnce betkveen treatnlent and enbarzccmcnt is vabwc, sincc m a q enhancements really arc trcatmerits, and EiH along a sil~tglecontisiutzm of vice versa. Trcdtme~itsand ei~h~~ncemcnts rliedical il~ttenrcndoizs;tbc diEerence bcm~ccnthem is olze of degree ratbcr than of kind. Secor~cl,they claim diat, since treatrTlcnts and ex~hancexrrer~ts involve only differexlees of degree, cases gerrnane to one are assit:nilahie to cases gcrxrtane to the odier. Coxlsistency requires that we treat relevzlntly sinilar cases in the same way, and since. cases of treatment and enhancement (negative and positiw eugenics) are zclievantly similar, cases of one ar-e assin~ilable,or logically linked, to cases of t11e other. Third, they claim tbat, si~icctrcatllient and enhancclnent are assiniilak?le to each other, cascs of oize will cause cases of thc otlier.This elnbodics tbc icliea of the dangcrous precedent. That is, case (a) xnay be prin~a&cic acceptalzle, xvbijte cascs (b), (c), arlcl (11) are xiot,Yet, becatzse (a) is rele'17antly slrrrilar arlcl thtzs assirnilable to (b), (c), a d (rr), doing (a) mould set a dangerous p ~ c e d e n tas , it wotlld cause jb), (c), and (11). Therefore, (a) should not he per~rtitted..~'~ Itlcoryarating aspccts of at1 three of the nlore pardctrlar arguxrlents that X have just laid out, the logical form of the more general slippery-s10~argument fii- the issue at hand looks something like this: 1,
2, 3.
4, -5, 6,
Case (a)-an instancc of treatnient, negCztiveeugenics-is priiiia f'cie acceptable. But cascs (h), (c), . . . and (n)-itlstances of enlzancel-xlent,positive eugenics-are unacceptable, Cases (a) throug11 (M) arc assknilablc, as tbcy cSiEcr &c>~-xl each other olzly in dcgrcc, falfirrg along a continuut-xl of cascs of the same type. Case (a), if pernritted, lviff be a p ~ c c d e n for t cases (17) through (11). Verll~ittingfa) will cause (b) thl-ough (11)Therefore, case (a) should not be pcrnritted.
If we arc to accept thc c011clusir~s1of this arhwine~it,then it iaust be sound. Thc c o l ~ c l ~ s i o~ntlst s ~ follotv Gora tbe prei1Uxh and pre1nises (1) thmtrgh (3) must atl be true. tfut the tmth of (3) can be questiorled. fn fact, treatmexlt d11d cnhanceIztent are differexlt in kitzd, not n1cri.1): degree, drlci they corresporld to distinct aims that can be clearly articulated, If this is corr-t.ct, then premise (3) is false, since cases of treatment ar-e not r-elevantly sin~ilarand not assinG1ab1e tr:, cases of enhancen~ent.Prenlise (3) is fa'tse o ~ r i n gto t l ~ efallacy of assiniilatioi~.Furthermore, if case (a) is not rclevai~tlysinilar to cases (b) tbrough (n), thcsi it is unlikely that (a) wtjuld cause (b) through (n) to occur. Hence premise (5) is False as well. C3kving to the Ealsity of m70 of its prernlies, tlse nrgunent is zrnsound. And becatlse it is urlso~irlcl,the ciailxls of diose t v l l ~believe that rlegi~dvectrgexlic treatlxrexlts ir~evitabtytvifl lead to p 0 s i l . i ~eugenic ei~liar~cc~nexlts are tlrlgl-ourlded.At the very least, tlze burclen of pmof is on those nrdkrng these ctaims to foormtllate a sound and more cogent a r p m e n t tr:, stip~3orttheir position. C o i ~ S i d e ~ a t i oof~ ~the s truth or hlsity of the a r p m e n t aside, it seems plausible to say t h t ~adcqrrd te regpla tions and safchruards could prcvcrlt tbc allegccli sfidc froin occurring.Tbere is 110 reason why puk?lic palicy and legislation canslot gwarai-ztcc this through a clearly spelled-out distinction bctkvecxz die dims drld rlleth~cSsof t r e ~ t i ~ ~drlcS e ~ iexlha~~ce~zlexlt t and ellforce the pertnissil-riity of the first d11d imper~zlissihiIityof the s e c o r ~ I . The ~~I 11egdti.lie eugerlics that f am defending has dffix~itiestvith what Iqliiip Kitcher has called 'kutopim eugenics."" This consists of a policy 'waranteeing reprodncri.~freedom in choosing whether to bring people into existence, as well as access to medical tecbnoloCqto r-aise or restore l3hysical and iiiental f~lnctianii~tg to, or rnaintaiil it at, an adecluate lcvel. These choices must be frcc of ally social or political cocrcion to prevciit people from cxistiiig &or econoGc reasoils or perfectionist iclieals. l1rc3vidcd that ~ I I ~choices is for the technoloti,~of tvhiclr tve avail o~irsel\7esirl I T I ~ ~ diese the purpose of prtlverltir~gor tmating disease, rather than enliarlcing dlready adeq~~ate functionit-tg, and tliat this tcchnolo%qis accessible to all, utopian eugenics call be a morally justifiaMe pojicy
Conclusion I have addressed twtj forms of gcnctic interwiltion in this chapter: gcnc tbcrapy to trcat discases and restore or raise pe013le's physical and mental i'iirlctionitlg to a ~mrtrlnjlevel; and gerletic exll-rarlcez~~et:~ to rnise peoglek
functionixlg alzovc this lcvel. I=;ene tberapy is x~~otivated 1z-y the x~~edical gc~dlof health prcjmotion tbrcjugh disease prevention and trcatlllent and is gl-ouxlded in the moral prirlciples of ~lontrralefice~zce~ hetzeficet:lce,and justice. It is mearlt to prevent harm to a r ~ dbellefit people by prevexlting disease in them m d providing tiiern with opportul~iticsto tlxldertakti: and complete p a e c t s within a life plan of their owvl making. X explained how gene therixp at diEerent seages of developing human organisms can aRect the ident-iries of the people who come into existence. In addition, X demoi~stratcdhow icleritity bears on our undcrs~indiligof benc6ccncc and justice in cases of cogliitivc gclie thcrapy If w e are to bene&t tbc greatest ~ ~ u r n b of e r peo~zleaffictccl. with different diseases, then there are good reasons to seriously consider shifting genetic research and treatment. priorir): away kom diseases like cystic fibrosis, Tky-Sachs, and 14untix1gon's to l~eart.disease, diabetes, and cancer, These reasons inclucie the con~yarativelysmaller nun~berof people wit11 severe but rare nlanogenic disarcfers, the larger numbcr of people wit11 more common multifactoriril dison-ters, the extent to which people within these two classes benc6t from treatment, and tbc fact thdt x~~edical resources are ~t tbat we should shift elxphasis ak~ayfmra g e ~ ~ e t i c scarce. Sorlle x ~ i g l argue rcsearcl~in gencral t o public healtb programs and prciia~ilcare, which can prevent lrrarly chronic dised~esin a sigr-tificaxltly large xlutrtber of people. Gene ther~pyhas shown sorrre promise in treating srrcl:, disorders as severr corxrbixled irxrxl~unedefit-iency (SCIX)), fatrtilial hypercholestcrale~rria,hemophilih and alpha-tltalassen~ia,but has not been pr-aven effective &?rmost &seaset;. Presently, the most eRectite course of actioi~is not to try to treat sewre genetic diseases but to preveilt them f o m occurring. As 1 a r g ~ e din chapter 2, tbis wc3uld ix~volvegenctic tcsti~igand selcctivc termillation of embrycjs with xllutations tbat would have causecl. tbcse diseases in the per>plc we othcmvisc wc3uld have brcjught ixzto existence. I also coxlsidered the prospect of genetic enharlcernent. and gave fotrr reasons why it would be imper~rrissibieto intprovc pliysicnl and ~xrental traits and capacities above the f~~t~ctional norr21 for people: It would inv.nlve uncair access to enhancement t e c h n o l o ~based on ability ta pay; it 'vlrould invo]ive an tlnaccept&e social cost in the &?rm of mental impairment as a side-effect. in some people; it w u l d , threaten to unifrrnUne equality as one of thc bases of self-respcct9 social stalziliv, and solidarity; ancl. it wctuld tbrcate~~ ta undermine indivici~zalautonoi~~y and rcsp~nsibility~ I characterizccl. trcatlllent and enl-iancemcnt as negative and positive forms of eugenics and arp~ecldiat axle does xlot inevitably lead to the odier. Finally, X
deinonstrated that the slippery-slope argulncilt advancecl. to support the claim that there is a silicle fmm negdtivc ta positive ertge~~ics is unsctund owing to the fallacy of awirnilatiot~and an ui~sttpportedclnin~about causation hetkvecn distinct types of cases in two premises of the arglment. i n 11rrr11at.lgenesis that raises adC l o ~ ~ i is n gailother form of interve~~tion &tionaf questions about ~ n e t i c sand et~genics.The molecufar biolo'q of cloiring, the mot-iv~t-ioirf i r cloil;rng human body parts, embryos, and even full-fie&ed humair beings, and whether diRcrent iitrn~sof cloiring are desirable and dcfcfcznsible on biological, i~~edical, arld especially i ~ ~ o rgrounds al need to be discussed separately
1x1 1997, 13x1Wilxxrut and his colleaptes anx~orix~ced that they had cloxled a cell front a six-yearviable lamb by transylax;rtiiIgthe xzrtcletxs of a so~~tatic old sheep to an enltcleated e g g . T h i s finding raised the possibility of cloiring human c d s to grow tJssues and organs i'or transphntaboir. It also raised the possibility of clolring complete human organisms. The Fascination surrounding the pl-aspect of cloirirlg human being has been tempered with caution, bowcvcr. Cl11 the rccolnlncndations of the Natiilrndl Riocthics Advisory C:ommissioir, llrcsicl.ent C:lilitan draftecl. the C:lonixig llrrcthibition Act of 1997, ~vbichoutlawed so~aadc-cellnuclcar transfer &or the p u v o x o"fm"tir7g a h ~ i ~ ~being, t a l ~ Signiticatl, the Act did not call for an oritright ban on all cloning research, but ix~cludeda f i ~ e - y e "sunset ~~r clause" that allokved itnportant arlci proixtising work to clone DNA, celis, tissues, arrd nonh~lmananinlals.2 One possible devt.lopment of this research is therapeutic cloning, where embryos are cloned from patieots\\vir somatic cells. Because a cloned embryo wctuld co~rtaina patient's ox~7nDNA, it could bc pr~jducedto dcvelop cells and tissues that ~votrldbe compadble ~ v i t bthe patient's in~mune systcln and avoid graft rejection. En~bryoscould bc clonccl. to derive cmhrycmic stem JES) cells, wl~icllcould he mecl to rcijtlvendte cells, tissues, ancl orgz111s darnaged front degenerative diseases like arthritis, diabetes, and Parkinson?. Cloning crxrhryos thus couid play XI important role in regeneratite medicine. I wlll iscu cuss this passibiiity later in this chapter. ES ceUs also could he deriwd from embryos created through X W that have been dscan-ted by fertility clinics, X wrll, discuss the moral implications of this particular sourcc of ES ccfls in chapter 5.Thcrripcutic cfoning is n c ~ ~ legal 7 in Bri~iin. Cknacfa issuccl. draft legislad011 in May 2001 perinitti~~tg stcm cell research, but prcjhibitixig b u i ~ ~ acfoni~lg n and the crcatioi~of e~nbrycr)~ solely br r e s e a ~ hplrrposes. And in July 2001 ,The U.S. House of Repre-
sentativcs vc>tcdby an c3vcnvbclming 1n;ljority ta ban cloning, not ordy &or rcyroduction but also &or inedical research, ever1 for tbcrapeudc reasons. The radoxzalc for a prohibition oxz clonixlg hrxrt:la~~s is uncSers~trzdable.It is not yet kmwrz whether tlie tecl~sziqlreworrfd he sak br the indirbidtlals resrrltixzg kom it. At a deeper 1e~e1,cloning raises metapl.iyt;ica) arzd moral q u c ~ i o n about s what makes US human. SpecificaUy?it has been a r g ~ e dtltat cloiling is nlorally i-epugnant aild should be banned because it involves a &?rm of biological manipulation that violates firndamental features of our hus~~ai~ity.~F"cl>r some, this tcchi~olohyevokes visions oEH~xr*;lcy$Brave Neu~ FfiP-ld, where cloning peaplc into different grc~trpsis part of a cornprchcnsivc prc~grainof sc3cial engi~ieerixigthat deprives i~ldivicludlsof tbeir &ccdorn. Aftl~ougi~ cloning is in marly res~7ect~sz extensiot.~of existing pmcedures of assisted reproductioi~~ such as artificial inserxriizarion and IVF, the asex~lalreproduct-iotz of gerletically identical copies of otlrselves seerms anathenla tr? our deep-se"ed coi~victionabout the uniqueness aild dignity of each person. For others, cloning does not threaten human dignip because cjjglit.)r is a firnctioil of muclt more than the biislodcal means of reprc>duction through which huxnans arc conceived and causecl. to exist.4 Ftrrthcrr~~ore, cloni~zgcould avoid i ~ ~ a nofy tbc diseases tbdt result frc>m sexual reproductioi~by preempting what Joscph FZctchcr has called ""gnedc mtiSctte,"VThese and odier related issrres will be diseussecl in this chapter. g (I)""r~.piacing'hloved one tvho is dyt'ossible uses of c l o ~ ~ i nincltide: ing or wlto has just died; (2) pmducing an ix-rdividual with specially designed pbysical traits; (3) producing a child for ail inkrtile couple, when all other repmducdve alternatives have been exltausted; (4) producing a child &or a lesl-zianor gay couple; (5) cloning either of twcn genctic p'irents, when al each of them is a carrier of a i11ut;~ntaUele tbat in n o r s ~ ~ rcprc>d~~ction wctuld cntiiil a significant risk of barring a child with a semrc disease; (6) ~xtit~ing stern ccus fro117 cloned ernbryos to rejuvenate fjssue"iclan-taged kot:rt disease in adults; (7)geneticaliy reprogra1nrnii2g clotzed preinlplaszradon exxrbryorzic cells to prevellt diseases by correcting xxttr~ttionsbefore the embryos demlop into people; and (8) growing organs &?rtransplantation. Intuitively? these possibilities fall along a rough continuum of moral justification, with (G), ('71, and (8) being the most justifiable and (1) and (2) tbc least. For while (6)-(8) are the xnost likely ta prevent harm to persons 'by prcvcnting, trcadng, or curing disease, (1) and (2) are the most likely tto cause harm to p e r m ~ ~ d btrcadng y t l ~ e msolely as m c a ~ ~and s not also as erzcls in thexnsclves. f will flesh out these intrtitioxzs by exploring the xxtoral
in~plicaionsof cacb of thc eight uscs I h ~ v cr~~entioned. After addressil~tg tbc biological aspects of cloning, I 1vill articulate thc grorz~ldson whicll (1)-(8) can or cdrlnot be rl~ornltyjustified. 1x1 exarnirzi~lgtliese issues, X will he guided zx~aitdyhy the Karltia~ldeontological i.t?jttnction to ""teat t11.i~xra~liv, wllether in your CXVI~person or in that of any other; always as an elid and never as a means only."" Cr~lcially~ this iclyunction says that it is morally permissible to treat people as means, but not sokly as means. I tltcn g)a n to suggest that, if tltc aim of cloning is to pmmote ltcalth by preveriting, treatil~g,or curixig disease ill people, then the strongest argwiIIents for clasling will pertain to (6)-(8). TIlcsc threc uscs effectively sidestep 111ost znoral al?jecdoiis because the cells that arc. clonccl. and their products am notlessetztial parts of persons withotrt any 111011a3 ~eriitusof their own. Claims about clorling .iiiofating the autonon-1.); tl~liquei~ess, a r ~ ddig11iv of persons are lnrgcZy unfou~ldcd,The rl~ainmoral collcerrls about clonit~g hinge a n the biological passibilitr)l of DNA damage to somatic-cell nuclei and the adverse eEects that asexual reproduction might have on the diversity of the hunraii gene pool. C:foning could lead to an increase in genetic r~~utations in ilzdividuals and the hrzrnan species as a whole, making people vulnerable to premature agixig and disease and thus harmillg them. Although it is unlikely that cloning wctuld be p r x t i c ~ don a scale broad erlorrgh to ir-zcredse die xlrt~x~ber of rl~titadonsin the htzxxran gclie poc->l,X explore h i s idea ir-2 response ta the clairn that cloxlirlg would reduce the umber of genelic aht.lorrrralities and birth defects in childreil.
Biological Factors Thcrc are twtj cloning methods ta pr~>dr~ce genetically idcr~ticalcopics of bumaii organiszns: embryo splittillg, and tbe nuclear transfer of somatic cells. E~nbryosplittixig consists in seitaratil~tguiidiffcreiitiatecl. erabrycjnic cells, or hIastotneres, at an early stage of a developing organism, Because they still are ~11diFe1-rntiatec5~ each cell is totipote~ltand thereforf: capable of giving rise to a diFerent ernbryo ancl a digereilt t~tirl~an This is the method of cloiling eiivisioned in Hudey's navel. C:foning tltrough nuclear tra1isfi.r is tlte method used by Wilmut and his callcapes to produce ""folly" and the one with cvltich X wilX be concerned in this chapter. Briefly, this consists in transpiiantil~tgor i~ljectixigtbc nucleus of an adult body cell illto an enuclcatcd egg (oocyte) of another aninial. C~onviiiced tbat past efforts to clonc: r~~ammals had Failed because thc dc>nor cell that slipplied the tlrtcletrs and the recigierlt egg were at digerent stages of the
ccll cycle, Wilmut et al. cut tbc supply of nutrie~~ts and thereby induced ~ ~ t in x\7hich the ccll stops dividtbc dcjnor cell ta gbablywctuld dcvclop 110r111ally and I Z O ~age prematurely or sufTcr f r o i ~any ~ adverse hcxltb ef~ nits s cells. Assui1I111g tbat there is coiapatibility fects of geiietic i a u ~ i t i ~ in h e t w e n the donor-cell nucleus and the recipiel~tegg cytoyasm, and that the donor--cell nucleus lzas been xxraking the ensytxte tefomernse all along, llarxrral telolnernse actiiviq and a norxrral rnte of cell divisioxl vvorrld occur in the cloned incfividual. But if the donor-cell nuclear L2NA has been exposed to ratlintio~lanif carcinogens, then the clone's cells would be coilsiderably older than its chronological age. It would age f ~ s t e rthan the normal biological rate, Srxch a11 indi.ri.idual xvcnulci be at i~~tcreasecl. risk of il~heritiliggcnctic mutations caused by crzmrzlative damage in the dollorcell nuclcar D N A and co~~seyucr~tly would bc xnore likcly ta experieiicc p ~ z n x u r eagirlg and disease, Xn fact, ge~leticistshave ii>trr.lcS that I3ollyk
gclies bcgax~to sho~vsig~isof wear not lo~zgafter her birth.The udder cell usccl. tc:, create I'lolly was from a six-year-old (very old f0r a sheep) with already shortexled telor~lercs,and research has sholvn tlidt X>ally's teloxxrerer; nm 20 7 4 1 sliorter than those of slieep of lzer snrnc age that were not cloned. l 2 These biological factors have significant moral implications far the clorring of htlman beings, C:toning could result in the existence of individuals who m ~ u l dexperience pmmattxre disease due to genetic mutations ir-r tbc dc~izor-cellI'lNA. This wctuld harm indivicludls by defeating their interest in a hcxlthy ei.nstence and livi~igout a rcasctnably disease-free lifc span,The possible biological ckrects of c l o ~ ~ i nong tbc aging process wt:,uld itldirectly cause hdrrn it1 people by pmdncing n diseased bodily condition that tlicy would have to expeAence.This is one xnoral gmund 0x1 which cloxling humans would be inrpertnissible. F n r t h e r m o ~if, cloning were pe~formedin vitro, then n~utationsIll1gbt occtrr cvbde son~aticcells were growing in culture, Even here, expastlre to certain envirnnmen~alcdctr:,rs of the sort 1 have mentianed might cause gei~eticdamage. Irz this scenario, it wotxld be difGcult to dctcrminc whctbcr the donor-cell nucleus was normat. or abizorr~~al; there wctuld be no way of asccrtai~iingthe extent of dalnage to its DNA due ta Eictors inside or outside the cell.Thtzs there would be no way of kno~vingwhether a cloned itldividlial wotild develop normdlty or experieilce prexnnhtrti, aging and disease. Here too the clotle cotzld inherit gemtic danage that cvould defeat its ir-rterest, once. it exists, ir-r having a xasonably disease-free life span and thus w o d d be ltarmed. The issue is not cvltether a donor-cell ntrcleus is a poterrtial person cvith a right ta be brought into existence. Rather, the issl~reis tbat a clonccl. individual, given tbat she exists or will exist, has an intcrcst ill living out a life span 1\7itbout hdvi~lgto experience premature a p n g and discdse..A~zdgiven that harm consists in tlie defeat o f a person's interest.5, n cloned persot7 lxray he llartned by llaving to live with prernatrrre disease resltltillg frt3trt ge~letic darnage ta the donor cell nrxclet~sthat is transferred to the oocyte.3b the extent that tltere is no way of kirolving wltetlter there cvould be genetic dan~age,that merely potential people do not have a right tr:, be br-ought into existence. by any nleans, and that the poterrtial risks in clonillg seem to outweigh thc pate~zdaiibcriefits, it seems plausible to say that 1\7c should reiaail~t011 tbe side of cd~ti011and prevent this statc of afgairs frcxn ot>tai~zi~~tg. This is the first set of biologcdl and xnoral rcasons for not cloning hrzman beings into existence.
More gcneralfy, as an asexual forin of reproduction, widespread clonilig tbrough nuclear transfer could rcs-tzlt in serious long-term costs to g c ~ ~ e t i c diversic~y.and the mlrvivz11 capaciw of the humar~species, Sexual repmdtlctioti allc~wsjirr genctic variation arnong offspring, wliich xxtiniinizes the nuxxrl-ter of deleterious xx~utationsaricl in trrrxi cxikanccs the ability of a In species tr:, adapt tr:, aild stlrvive in cl~angingphysical en~ir-anments,~ particular, genetic varic4tioilcan help organisms evolve in such a way- as to cope better with infectious agents.This conkrs a critical surviwl advantage 011 tbe hrrman species, which crialzles us to transfer our genes into tbc next generation. C:lonilig interferes with tbe rate of adaptive evofution, w h c h is t ~ ~ u cslower h in asexual p0pulatioit~f4C>xie reason for diis i s that two or xxrare \?ex~c.Licial xxrutations that arise ixi digercnt lineages car1 be colnbined into the sarnc liriedge thmugh sex, an advantage that sexual populatiotis have over asexrral ones. Silver claims that, in birth defect-s resuldng from an abnormal number of chromosomes: such as Down syndmme, the &normality occurs becarrse of mistakes when genetic material is reduced by half in the pl-acess of egg &orr~~atioit. C:lottixig wtjuld greatly rcduce the likelihood of this ~ c c u r r i ~ i g , because the process of sornatic-cell tra11sfc.r ilivc3lvcs no such reduction in genctic t~~atcrial." Morecwr, in recessive disorders srrch as CE'l'ay-Sachs, SC:A, and PKU, whcm the agected Ghild inheries tkvo copies of a xxrutant allele carried by each parent, clollitig otie of the pdt-erits wotrld rncan that only one defective allele vvorxlci be trans~xrittedto the cXoxiecS child. Strictly spe"hng, the clone .\jvcjr_rldbe the genedc siMi11g of the prellt. MOI-eimportantly, the child would, be only a carrier of the trait and therehre cvould avoid havitlg t l ~ edisease.This corresyonds to scenario (5) desckbed earlier in this chapter. The gcncral incidti~ccof birth defects in cloncd children wtjuld bc lo~%7cr tbait that in naturailly conceivecl. children. In the light of these poirits, one coirjd argue that clotiirig wottld improve the l ~ u m a rspecies ~ by reducing the incidence of disease in people Asstrr31ing that parents could clioosc clonitlg over sexual xxreans of reprodnctiolz, individuals who canre into existetice tlirougl~clo13I119 in the prescrit atid near tilture migltt bellefit from it.Yet in evohrtionary terms t11e human spe&es as a whole over many generations migltt be worse off if asexual &:,rms of reproduction like clolling became widespread t e o n Eisenherg supportfihis pasitioit: Cloxling would be a poor rr~ethodrtzdecd for improving 0x1 the hurr-tdn species. Xf \nildely accepred, IT would have a devastating trr-tpact on the di\rersiv of rhc
fium*~ngene pool. Cloning would \elect for tram t l i ~ lt i ~ v ebeen rucces,ful in the p m but tl12t xvlfl llOE nece"s"idrily tte adaptive. to a11 ux~predtct~~ble f~t'rrrure, Whatever phenotype, m~gl-rttte produced would t>cextre~1-telyvulnerable to the unccb~-rtroflablevici,.;ieudcs of the envlrunn-tent."
With respect to the survival capa&ic)r of the hrinlatz species over m n y generations, clonir-rg mrauld be at odds with evolutionary biolo'q. There are moral i~nplicationsof this biological point. If cloning dimirlished the diversity of the gene pclr~land conseyt~cntlyour ability as d species to adapt ta a ch'3nging phyGicdl enviri3nr11ent~ then persons i11 this and near future generations xndy bcne&t in tbc respects Silver highlights. But peaple in distant fittltre generat.ions might he l~anrrecfhy their inabiliv to cope with ir-zfectiorxsagerlts, arnoxlg other threats to thexrt, in the cl~vimilri~cnt. Ibtential presult benefits to sotne xxrtlsr be weighed agait~stpotential ftrtrtre harms to others. If tlte number of people wlto cotild he harmed in the distant ft~ttlrc"is much gr;irater than the number of people who stand to benefit from being cloned ir-r the present and near future, and if w e have a greater duty to avoid harm to a largcr group of people than to benefit smaller group, then it seclns ta follo~cvthat the intcrcsts of lirrture people not to bc harmed o u ~ c i g bthe interests of present people to bcne&t frc>in ciot.ling.This a r p ~ m e i hits ~ t to be advanced tentatively, holvmr, since it is difficult ta deterxrrix~ewllzlt the probabiliv of irz~rrnwould be ta f~itrrre people if cloning became a regrlar practice. trl generni, though, the clainrs of tirture people not to be harmed have as much moral w i g h t as the claims of present peaple to be benefitedW11at matters is not rvl'rptz they exist, but tIrtnr they wrll exist. We cannot discotint their claims simply because tbcy do not yet exist and only 1\7ilf exist in the distrtllt ft~tt~rc. E~stcrice, rather than time, is whdt makes prcscllt and filtt~rcpeaple cqrxdl in both tbcir ~aetl~pfZSBsi~dl and morrll s t i i t ~ s . ~ ~ Sexual reprodrrctiot~also confers a survival advantage on a species by e l h a ~ ~ c i nI g) N A repa\ir xxtwhanisms in orgallisms beiongillg to that species.Tl~isresults fro~rtthe process of ""cr>tttcrossix~R,'" which coz~sistsixz the fusion of two celis in semial reprodzlction so that the genetic nraterial of each parellt cell becames enclosed inside a single menrbrane,l~Enzymes are then produced, that can check for m d repair &amage to sequences of chromosctmal base pairs. In this 1\7ay, the outcrossing in scxtlaf,reproduction ca1.r prcvelit the occurrcllce and expression of genetic mutations. C)ver ~ a a ~gencratic>i.rs, ly cfoni~~tg, as an asexual k ~ r mof wprclrductioi~,could result ir-2 die cxpressiox~of rimre deleterious xxrutatioxls ancl a higher incicierlce of
premature aging, disease, and deatb in hrxmans. It could thrcatcn thc ndtural variation necessary for one generation to strwivc long criotrgh to pass its gerlcts on ta the rlext and over time r l ~ d yadversely a&ct the abiliv of the kuxxiar~species to survive.This is the seconcS set of biological ,znd xxioral reasorls agdixzst Co11i11g. Sonle have claimed that cloiling on a bmad scale is so unlikely that its eft;tcts a n genetic diversity are not mrorthy of serious consider-ation. For exanlple, L2an L3rock says that it "is not a realistic concern since l~unnan cloiling wcntxld not be usecl. on d ~vicleerlough scale, substantially rcplacing sexual rel>rc3duction,to have the fcared effect on thc gcrlc pool. Tbc ~ 1 si114jority t of burnails seem quite satisfied with s e x u ~illcans l of rcprc3drtction,""2'"But it is not so f a ~ ~ c ito f ~ixnagit-le ~l a substarldal rlrrrl~berof pmspective pacentmvI10 triigiit wxlt to avoid playing tlie game of genetic roulette arlci opt h r c l o n i ~ ~If g . b t t i p a r c ~ 1knew ~ ~ that they were carriers of a nnl~tailtaflele that coulicl cause a recessive disorcfer, then they nlight choose cloning instead of sexual reproduction to eliminate the risk of having a diseased child, Furthermore, if' prospective parens belicved that clonil~tgcotxld elin~inatci1Iutai.rt alltclcs thdt i1icreaseCf. lifetime strsceptibili~to xnodcrately severe conditions like ostcoarthritis and cardio>y;iscr;ilardisease, thcrl d ~luxnlzerof them xnight choose clonil~tgover sexual ~-eprodnctiotlto have childre11 who would not be strsceg~tihle.'T'his sce~larjiornay be less rather than xrtore likely ta occur ox7cr dxne, Sdlt, the p i n t of describing it is to illustrate how clonillg could increase the number af genetic m ~ a t i o l l in s humans in the long term .And eve11 if' it did not adwrsely affect the human species as a mrhole, it could illcrease the number of mutations mritltin Fanlilies that reproduced through cloiling over r1Iaily gcncra tions. In tl~issection, I hdve addressed solne of the passible long-term biologcal risks of hrxman cloru~~tg and hcive explorccl. the xnoral iniplications of these risks b r tiltrim people,This is not to st~ggestthat all. fctn~isofclo~ling sllorrld be banned. C311 the corltrary, there are coxrtpellixlg xrtedicdl rcasoxls ii>r certain fanris of cloning in particular cases diat may be of great bellefit to ~ o p l eIn . the next section, I .vvd examine these &3rms and the effeet-s they might have on people, payitlg pardculai- attentJan ta the qrlestioil of cvhettler they are nlarafly pernlissiMe and on w l ~ a grouncfs t they would be permiskblc. More speci&cdlly,1 ~ v i evaluate l them it1 terms of ~%7hcf;hcr tbcy are c ~ ~ ~ s i s t with e l i t the Kantiai-2 ir~j~xnction to trcat persons not solely This 1\7iU be coi~strucil.brc3adly as means but also as enclis in thci~~sclves. enougb~to incltrde the question of 11o-w cloning at-f-ectspeople's r l i g n i ~and
tbc autonoi-r~yto make choices and act in accord with a life p1211 of their owl1 making.
Means and Ends Earlier, I cited eight possible b r m s of cloning, though only three of these pertained to the pmducti.on of full-fledged human organisms, The others pertained to embryos, tissues, organs, and other human body parts. Let us exaGnc each of these m70 gencral &>rr-r~s of clol~ingill more detail. Suppose that the parents of ;L recently deceased or dying child want tc:, cfonc: a11 individual who is ge~~etically identical to that child and thus ""rplace" it: to cornperlsate for their loss or else carry on the fatnily line, If the the11 the cloned sole intent of the parexlts is replace~zrer:ltor cot?-~per:lsatic,n, ixlclividrral vvottld be treatecl solely as a rllcarls, tlrllich tlrot~ldviolate the second formulation of Kantk categorical imperative, A persoil is not a mere extension of its parents or siblings, and to treat one as suclt would deny tlte intrit~sicdignity and. wortlt one possesses in virtue of the fact that olze is a h u i m ~agent ~ with tbc car)'~ciqfix- rc.ason.ll A parent alsc:, may want to create a child with tbc same phy"ica1 features that he has, which wctuld be the highest form of egoism and ndrcissism on the parent's part. Yet, despite the apparet.lt reptrgilalce of creati~lgarlrzther individual in one's c m n irnage, or to fiS1 a vc)lcS left by a deccasecf child, if the clox~ewere loved arlcl treated with the digx-21~ and respect coxxr~rrar~cled by its intrixzsic worth, then cloning nligl~tbe morally justifiable on Kai~tiangrounds. Mthotrgh the intention tr:, clone the cltild suggests that he or slte would be t the cltild is treated as a unique incfividtreated instrurr~entallythe f ~ c tltat uat. once she exists is c r i ~ u g hto dispel any moral yuali-r~sabout thc parent's behavior.What matters is how people arc. treatccl. over the coursc of their ~ g to exist. Besides, parlives as a whole, not tbc intentioi~&or c a ~ s l ~them of reclsons,some of which rnay seem quesents have chiidret.1for a F*~arier)i donable, ancf there is no jrxstificatiox~for treating the reasoll for hz~vi~lg a cloxled child as a special case. Pmnts may decide to clone a brother from a soil dying &m a Mood disorder like lcuken~ia,Because the cloned brother would be genetically identical to his sibling, his bone marrow would be campatiHe with that of systcrn.As soon his sick brother and tvould not be rejectecl. Izy his in~rntll~e as the clol~edbrotbcr's ba1.r~xnarrc:,\v was mature criougl-r &>rhanrcstirzg, it could be extractccl. and transplanted illto the older brotl~crta cure him of Aya1a of Vlialr~~tt his disease arlcl si~vchis life. This recalls the case of A~~issa
(;rove, C:alifors-zia, in tbc la tc 1980s." While Anissa was dying slc>~vLy fr~>m leukexnia, her parents decided ta h ~ v eanother child (a daughter) 011 the chai~cethat she worxld be a donor match with Aitlissa. Fortttnately, the hone xzrarrow of the yotzilger daughter, Marissa, was compatible with A~lissa's,tlie rmrrow was transplar~tedwhen it rnattlre enorlgh, and Anissa's life was saved. Mthonglt at first blush the p r e l ~ t sdecision ' and action seemed morally mjustifiaMe, afl accounts now suggest that tltc child cvho was conceived in order to save her sister's life has been loved and rez spected by her p'irents and sister as a distinct individual with her c ~ ~ 7 1 - intrinsic worth. They have treated her with digi1itr)r by respecting tbc Eict tbat she h a a life cof her o~vi~t. Is? other words, the Ayalas w c r ~treati~lgthe p u n g e r daughter as a rnems.Yet they have not treated her scllcly as a xxreans, htzt also as an erzcl in itself. In this arld the ottier case that I have !?resented, clollitlg a genetically identical but numerically and qualitatively distinct ix-rdividualto save or re$ace another docs not by itsell'imfly that the cfone is treated sc)]iely as a means. If he also is treated as an end in itself, then the act o f cloning a hui m n being is not inherently morally o!?jcctionable, For, on the Kantian view, treating a person as such in~pliesrespect &or t h ~ persaiz t as an autaizornous locus of dig1itr)r and worth, one whose capacity for reason ellables tiirrl to tiave interests and rights of his ollit:~.Insofar as respecting a person trtealls ~zplinIdirlghis interests and rights, arld insofar as cloning does not thwart his i~-zterestiior violate his rigllts, a penon is not harmed or cvronged just because l ~ has e been cloned, Suppose that, instead of conceiving another tlaughter through normal sexual reproduction a d risking the oclds that Marissa's bone marrow would not be c ~ s ~ ~ l ~ a twith i b l eAnissa's, the Ayalas cfoiied oize of Anissa's soxnatic cells and 1%7ercable to coizstrrrct an e1nbry.o ~vhosccells had the salnc gcliedc xnatcrial as the original cell.The child born Emm tbe einbryo wotxld he gellcttically icier~ticalto Anissa and ttltls would be a peifect dos~or xztarch. Agrilil?, tier bone mdr~-o\vwould be transplant-ed into her sister, who wotxlcl not have to worr)i about graft wectiolz dtle to an adverse iin~ntrr.le respai~se.L3ecause o f the genetic idt"ntit)i bet~veenthe donor and the 1-ecipient, the transplant would haw a higher chance of success. The same reasoning applies in this h?;pothetical scenario as in the actual o n c Even if the donor were cloned from oize of her sister's cells and were a geiietically idtr~dcdltwill of Anissa, there xvcn~zldbc ~ ~ o t h i l i11oraUy ~tg ol>jectioizable about tbc prc>cedure and its outcome if the parents treated the cfonc respectftxlly as an ir-zdividrral wit11 ir-ztrix~sicvvorth over die corrrse of its life.
In a siniilar case, A&ni Nash was born in August 2CIQO fro111 an cr~ibryct selected specifically bccdtrsc its tissue matchccl. that of his six-year-old sistcr Molly?who had a deadly Uoocl disorder." The parents s~lcctedthe ernhryo arlcl allotved it to dewlop into a son so that stern cells c d d be liarvested ii-01~1his cord blood 2nd trar~sf~zscd into Molly?therelsgr creadx~ga new blood supply and immune system in the recipient. They had a second child in order to benefit a first child, and in this rc.gan-1 they used Adam as a means. As in the case of Marissa Ayala, however, Adam's parents have trcatcd hini with lt~veand respect as a uniytrc person. Frc)m the &ct that tbey treated thcir child as a rncd~lsin causi~ighini to exist, it dc)es not follaw that they hdvc trcxted him solely as a xncans. Insofar as they have treated hirn as a11 elld 111 itself, one could not xx~orallyob~ectto the xxretllocl or rftasoil for brirlgirlg him irlto existe~lce.These cases invnlve the distincRut this tion heavcen the natural and deliberate pmdttctiot~of oK"i~?rillg. distinction sltould not matter n~oralfyFor, as noted earlier, parents have children &3r a variety of reasons, and it is cjjficuft to distinguish jrrstifiable from ugustifial-rle ~-eitasol~s f i r procreatrion. Also, how one is treated by others over thc course of cri~e'slife is xnore r~iorallysigliificant t h ~ ntbe rcasons &or causi~~tg oize to exist. Cgcorge Ai~i~ds writes tbat "the C I V I ~reds011 ~~ to clc>i~e a11 existing htrmai~is to create a genaic replica. Using the bodies of chiidrtln to replicate the111 erlcorrrages all of 1.1s to devzllrte chifdrex~and treat then1 as ixlterchaxlge~1171e corxlmodicies.""" But my descriptiol~of the actual and hypothetical Apla cases, as kvelf as the Nash case, sltovv that both of Annas's claims are faclse, In most imaginable cases, there would be complex Rasons ibr cloning. If a child needed a lifesaving organ transplant, parents nGgbt create a genetic replica through clonil~tgso that the genctic identity bcm7ccn Bbline enwctuld not he rejected and the diseasccl. child sured that the transpla~~t wctulci s1~~rvive. MQ~CCCICIVC~, i11~0faras tbc clc~nedchild was trcatccl. as a11 e i ~ d as tvell as a xxleans by liis prerlts and other relcva~ltparties, clo~litlgwould not devzllrte the vvortlz or trnderrnirle the digniv of the child. Anotiler scenario in which clo~litlgmight be r~lecficallyand xnorally justified is one where a couple is i~lii.rtile,due either to inmlaturc. sperm or a fokv sperm corrnt in the male, or damaged GUopiall tubes in the female. Even Itere, though, cloning mrauld be j.trst%ed only if the couple bad exhausted a13 other k3rms of assisteel. reproduction and did not undergo the proccdurc solely to have a child with particular traits. Lesl-ziai~ and gay couplcs also might decide ta h ~ v ca cloned child so that it would be gcnetically related to at least one of therm. One partner would provide the nrr-
clcus, thc otber tbc ~nitocbol~drial I3NA and cyt(lrplasm.Yet one would have to advancc a pers-tzdsivc arhwrllent &>rthe il~ttrinsicvalue of g c ~ ~ e treic latedzzess hetweer1 parent arzd child to justify creatixlg d child throrxgh cloxling iirr t h i s purpose. Sorlle rl~igl~t hold that we xzatur;illy wmt to have orxr okvn gexleticaify re-la ted cliddren a~vingto a " ~ i n l e v hstinct" ~l pogrammed into our g e r ~ e s , ~ But this idea implausibly stlggests same form of genetic deternGnism, as thou& we were compeUed by ozir genes to have the desire for chacll-en who are gcncticaHy relatcd to us, Tr is iir~~ff;iusil;llc because, as I ar~weclill chapter 1 , genes done do not detertnilzc the desires, i~ltentions,arid other illelital states that ~nakeus persons.Who we arc as persons, i11clucii~~g the partictllar desires we havel is not silxtply a frl1lcriot.1of otxr genes. Moreover, &ere are five q i ~ e m Opax~gthood, f only two of tvIlicll are f~~iletic. n the qtrestiot~of how cloning would agect pcrsod~ooilancl our htixxrarlit??;Axlxlas arptes ditts: Cloning would also radic'llly alter what xt rileam to be human by rrepllcatrng a hvmg or dead llu~lian"oelng ascxuaUy to produce a person \wth a \~n$_~c parent. cloning we will tore r o ~ ~ ~ e t l ivital i n g to our The danger is that tlirc>ughIiu~lla~l h ~ r n ~ ~ ntlie i t y ,ul-tlqueneu (an3 therefore tlie value and (Ziglity) of every human, CIloning represent., the height of genetic reductionism an3 genetic detertl~~n1 ~ r n . ~ ~
AgAw cve sltould take issue with Annas's clainls. Leavitig aside tlte nletapltysical distinctioil betkvecn persoils aild ltun~anbeings tltat I drew aild defellded in chapter 1, let us go along cvitlt Annas aild use "pcrson" and ""human" i n t e r c a n g e l Crratji~ga genetically identical cloi~eof a parent or sibling does not amount ta gcnetic rcdactionisrn or detcrminisrn bccause person" identity or our humanity is not equivalent to gclletic idcntity Czloning by itself does not tbrcatcn thc uniyucizcss, value, and ci;igzity. of persoxls, I-Iak7itlg the saxre DNA as a partr.1:lt or siI-tfing r n d y give a cloned child the sarxre gene& phyGi"" features as that paretlt. As 1 have ar~tecl,hokvever, personal identiy consists in the persistence through time of one and, the same indkidual identified with a body, brain, and a set of mental states including desires, beliefs, intendoils, anc3 n~enloriesunified fiorn the consciotrs prcscizt. The nature and content of these states is shaped as 111t1ch by if not 111orc. so than, one's social and physical eizvironment as they arc. by one's genetic xnakertp. Also, tbc 1\7ays in which the geizcdc xndterial ill the dollorcell ~~ucletls exprrsses itself in the clone'.; phenoqi~icmits will be a function of the epigexletic process of development from ttze e r ~ ~ h r yt.oo f-tlrther smges of demloprnetzt of the htlrmn orga~lism,This it~volvesinterractio~ls betmreen and, among diffexnt stages of cell diEerei~tiation,as ~vellas the interactioil b e ~ v e e ntlte embryo or ktus and the uteril~ee~~vironment during gc~.s~ation.There are different PI-ohabilitiesof genotypic pcnetrance in digerent people. C;cuzes that arc expressed as iclientifiable phyGicA traits ill tbc dc~norxnight not be cxprcsscd iiz the clone. Silnply having the same geizes as the perso11 &3m whose cell one is cloizecl dc~csnot mean that the clone will be idenricd to its dotlor in l7hysical or other mlevatlt respects.
The gcilcs that a cloiled ii~tdividualinherits frcxn a parent or siblilig illay very well influerice the pqchological prcjperties in which pcrxmnal identity cor:lsists by shaping the pliysical prupeaiemof-the body and brdin that gcnerdte ancf s~~staitz one's p ~ y c h o l o ~Still, q . genes alorle cannot nccount far the distit~ctivenessof ow's mgi~itiven11d ernotioxlal experier~ce ofand respoiiise to social and physical envimnmeaiits and tlterefol-e callnot comyleteiy determilze the natut-e and content of the mental states definitive of personhood and personal identity. Genes influence who w e are only within these envirc->nmeiits.So it is unlikely that gcilcs cotxld be the pri~naryexplanation of one's psychological properties, o1\7ing to the complexity 111 the ways thdt eiivirc>i~ineiltalfactors play a causal role in the e t i d o m of one's cog~litiveand ernotional states. Nor can gcxles nccozrxlc for the l7iienornenologicdl qtrality of bril-ig consciotrs of having these seates. Finally9the facr that palrent arid cloned child would he of different geiiierations and tberehre develop their psycboloCq in different social environn~entsmeaiiis that their mental states kvould be qualitadvely disdnc t. At le;~stone eiapirical study of the psychological traits of genetically iclientical twills supports these cfainis. In a qtlcstionndire devised by psychologist Thornas Rouchard, thcrc was a 50% ccorrclatiorii betkvcen the persox~aliqtraits of gerletically idendcal twiz~s,based 0x1 different responses to e This stlggests tbnt at least iiajf of ot~eSps~hological the s a r ~ ~questions." traits are due to environxnenta1 factors opcrat.ing independenciy of or in con,lunctioiii with genes. The more general upsl~otis that genetic identity unkrdeterminrs the sense of self that d.evelops thmugl~one's experience in social and physical environments and one's construction of a mif'ted life plan with godls and prcjccts that cctnfir ~ n e a n i ~ logn oliie's life. In RouchL%rd7s wcjrds, ""sfvcs, udike cells, can ncmr be cfoi~ed.'"~~) "Itinlately personhood and persoliid idciltiv are not solely or even priniarily filnctions of one's genetic arlcestry rtlg;~scfiessof whether one came into existence throzlgi~cloning or rlorrllal sex& repmdeictivt.: nlcarls, Tlzese consideratio~lsshould dispel any worries about ge~leticreducr-io~~is~rt or genetic determix-risnl. A ~ l a t e dconcern abaut cloriiing l~uxr~an beings is that it threatens to undermine a person's k e d o m , her arrtonamy in &3rming and tlndertaking prc3jects within a life plan of hcr C>WIIi~~aking. Rut ho\\7cvcr egocentric or otbcnvise misguiclecli parent" aainis xndy be in wantiilg to prcjduce a cfoile of themselves, ei~ts~~ring genetic iclientiv through cloi~i~~tg would not neccssarily restrict or ttnderrl-tir~en child's freedorn to develop a u ~ ~ i qiwiot~,
lablc sclf.What restricts or undcrrnincs a child's frccdc3in, rather, is p'ircnts' refusal or ii~tat3ilityto allow thc child to develop her ~ ~ ~ life 7 1 plan 1 and vdlzles by inzponng their own plan and values on her in an atternpt to coiltml her life. By not nlfc3wing the Ghifd to for~rzand pirrsue her otvil coilceptioil of a gc>odlife, parents \ridate what Jsel Feinbeq has called ""ahifdS right to an open tirture."% This pltenomenon occurs all too oftell in many Camilies. L3t1t stzrely it mrould not be confined to those with cloned cltilfdren, because cvbether pal-eilts I-espector deny this right to their children is not a functic?~~ of geiictic rclatedizess bem7cciz parcizt and child. The reas011 why concerils about cloning undermiriing hurnai~digzity. arc xnisguidcd is that tbcy focus 011 tbc biological xncans through which hzrlnails corrze into cxistei~ce.Wepossess digniv in virttre of being persoils, 1 - 1 0 ~sif:l-Iryhuman beings. S i ~ c persoils e are psyclzological rather than bioof our- nutoilornotis logical kinds, digniv is a fiznctiotl of our psycholoGw9 desires, beliefs, and intentions, ratlter than a function of otrr b i o l o ~To . be sure, b i o l o ~plays a necessary wle in our mental lik insofar as structtlres and firnctions of our bodies and brains geneme and sustain our psycholohy. But biology ca~zizotcompletely account for all thc features of our psychology. Evcn grar~tingtbc gclieral iir~portaizceof b i o l o ~ yfor personhood, tbc particular biological Fact of the rcprc~dactivc.rnca~zsthrough which oizc co~rtesinto existe~~ce is of n o red ~rzetaphy"jcdjor ~rtoralsigilificance, Whether one is conceived nr~dwmes into exsteilce throtrgh an nsexliral hrnz of-~producrionlike clonit~gor thrc3ugl.1 sexual ~prodrrcrionhas little to do with what makes one a persoil worthy of selfr~spectand respect from others. Oniy if the production of genct-ic identity betcveen parent or cltild (kvh~3,to repcat, xvould be the genetic sibliizg of the p a c i ~ t )through cloizi~~tg were an ii~ttegralpart of tbc parent's plan to contrc3l the child's life wctuld cloi~ingbc xnorally otjectioizdl?l.3le.It x\7ould be ot3jectiondble on the g~-ouildthat it w d d violate the chiId9sautoizolT1y By themselves, thotigh, clailing and get.1et.i~i d e n t i ~are t?-1oraXXynezltral; no lxzoral d u e attiiches to dlexxr, After all, tve n-Iake no n-~oralJrrdgxxrex~tsabout the fact t b ~ genett ically identrical twrins result from the moilozygotic ~ v i n n i n gof an embl-p in the namral unassisted &?rm of human repi-aduction.This is largely because the tkvins go on to develop as ~ltrrrzericallyand qualttatit~elydisdnct individ~idlsin virtuc of dcvelopirig distii~tctpsychologcdl propertics ovcr tin~e.Yet,in thc case ofgc~zeticallyidcritical m~ins,onc is effectively a cfoizc of tbc other.There is nothiiig inhcrent~yin1111oral or morally ol>jecdoi.ralzle abotit the genetic ideiltiq elltailed by cloning,Wlzat is ixn1-nor;rt is the use
of clonirig ta prcjduce afhpring who wtjuld be treatccl. as illere i ~ ~ e a ntos oize of the olzjectionat?le en&s thdt I ham described. Reiterati~~g the lztaitl points iri this a d the pmceding section, tliere are wotlld ~ g be morally objectionnbie: (I)if it three instarlces iri which C o r ~ i ~ erltailed genetic ddimge to the donor-cell rlucletls arld restrted in prelrtamre disease in a cloned human being; (2) it; as an a s e x d ibrm of repro&ctj.on pracri.ced on a broad scale aver mall)r generations, it adversely afl. fected genetic diversity, increasing the number of m~rtationsin humans and liniitir~tgtheir ability ta adapt to and sunrivc in changing physical crivimnillents; and (3) if it illcant trcatir~tga cIc>n~d iridivichidl solely as a Incalls and not also as an erld in itsclf. AB of these illstances would be morally olzjectionable because they would involve i~artnto people. But none of the111 derives froxrr ungrounded and xx~ispidecStvorries about genetic deterrniilisrn or gerletic reductionistl-t t h ~ a t e n i n gthe zrniqt~erlessof humans.
Cloning Body Parts It is worth elnphasizi~~tg that, when thc Natioizal Bioetbics Advisory C:orni~issionrccommcnded a ban on ht-lman cloning in 19997, it also rccomi ~ ~ e n d cthat d cloizixig of buinan cells be allo~cvccl.b r thc purposc of producing tiss~iesand org;Ins,?'his is signiticant because, by cloning these htumn body parrs, wtiicli are not identical to persorls and have no irltrinsic xx~oral statrls of tlieir c3tv1-1,we eEectiwly sidestep any dist~irbi~lg nmrd aspects of cloning firll-ifedg-ed human beings. The most compelling reason far clorring of any sort is therapeutic. In the case of p m h c i n g a genetic replica of an existing person h r n one of its somatic cells, the purpose may be to ensure that there will be a gcrleticdlly idcritical dunor far a transplant to cure that person of a life-tbrcatcning discase.Yct the same rcsult could be achicved by cloizing specific cell and tissue types from afi>ctccl. persons in order to create tisstles a r ~ dorg;Irls tliat could cure these sarnc people of these same diseases, If this type of clox~ixlgtvere to become feasible, tllex~ there would he no Irioiogicaf or ~rtedicafneed CO c l ~ i ~ eL I ~ IConsistei~t IS. with the point I made in chapter 2, the purpose of cloiri~lgkvoulci not be to create more people, but illstead to improve or nlailltaill the healtlt of already existing people, It wtjuld bc difficult ta find aizythil~tgmoraLly prot?leiaatic alzotrt clonil~tg h u i ~ ~ acells n &or the tbcrapeudc purpaw "of cctntrolling or curir~tgdisease in people. If this procedure were prcjMematic, then it ~vouldeither bc because it resulted in solrte bn11of physical, cogllitive, or ernotional Irartx~to peo-
plc, or because it underminecl. personhood and persorldl icleritity With respect ta tbc first point, if clt311i1lgcells a r otbcr body parts is by dc61rition therapet"tim17d can corlerc3l. or ct11-e disease without any harn-tf~il.ade efe only be hetzeficial to people. With respect fects, tlien the p m c e d ~ ~ rcould to the second point, fiun-~dnbody pdrts am not iderltical to persons. Atthotrgh p e r m n ~ r econstituted by cells and otl~erbody parts, they are not identical to these parts. krsond~rarrcbody parts; but tl~e):arc>not body par& and canilot be described or explained endrely in bodily terms. Personhood and pcrwoal idcr~dlayco~~sist in more t h ~ i rthe physical constituerits of bodies. Furthcrmorc, at the biological level of cells, tissrzes, ancl. orgalls, tbcre arc no individuals with the xncntal capacity fix i~ltcrestsand rights in ~*7irtueof tvhich they might be flamed. Cln neither point, then, is there arl)ithir~grnornlty ol?jectiorlable &out clorling htl~x~dn body parts, Yet, it is becatrse of the causal dependerlee of our psychoiohy on our bioloCgythat clorring body parts can benefit us as persons, giwn our interest in. not experiencing prenrattxre aging aild disease, Iir theory, researchers migbt be aMe to remove a small a m o m t of a particular type of tissue fimrn a patient, dc-differendate the cells in czrlturc, and tben genetically reprogram the cells to differendate into a specific Zrii~rl.of cell &or a particular orc and not be rcjectcd gan that could be rccognizcd 'by the i n i i ~ ~ u nsystem by it, This type of regenelr"ative medicine may be realized sonnsr rather than later. Researchers have learned hotv to crrltivate hrt~x~dn clxrbryorzic stem cclls, which are tltldiffererltiati-cl and totipotent, to construct ctlstornmade neo-organs,-".qIdeally9we would mrallt new tissues and organs that cvould replace diseased ones tr:, grow witl~inthe persoil ratl~erthan within an artificial environment. But presently the most feasible mray of doing this is to grow the cells in culture and then tra~rsfertbc xnanufacturccl. tisszrcs or organs to the affected areas of the body. The cells wctzrld bc trarrsfcrrcd from the c u l t ~ ~ xncdiu1n, re in the form of a three-din~ensioi~%%l iaatrix, to the site where die desircd tissue gro~vthwould u x ~ f o l d Sorrte .~ success aIready has been acllie%~ed in this regard wit11 the xx~dnrxfactrrreof artificial. skin and cartilage. It is instrtlcti.ve to explore the therapeutic pronrise of the sort of geiledc teclti~olo~q I have been discussing in this section. C:onsidei- polycystic h d ney &sease, in which. cysts for-m in both kidrreys and gr-adnally become enlarged, destroying nor111aI tissue and essential frlirctiorrs of tbis organ. Tbc genctic dcfcct thdt causes this disease xnay be either dc~mi~~tant or recessive. i ~ ~ o dofe i~~tl-reritance usually have no s y ~ n p t a i ~ ~ s Those with a dc~rlul~tant tzndl. adrrlthood; but those tvith a recessive xxt~deof inheritance have, se-
vere illness in childhood. Srxppaw &at an adult male who is a11 only child develops the disease. Because his i~zotbcrh a the disease and his gather is diabetic, xzcither can donate a kidl~eyto their soil. 1x1 such a case, tissue could be rc~xrovecl.konz one of his kidnejrs and culaxrcd cells frc3rxr the tisto replace tlie getzeticslly defective sue c o d d he getzeticafly reprogrxnr~~ed cells causing the disease,The same could be d o i ~ eib1- a younger child with the recessive genetic defect ca~rsingthe disease if neither parent is aNe or cvrllrng ta donate a kidney ta hirn,This would avoid l~avingtr:, clone anotbcr hrzinan being who i ~ z qor may not bc a coiapatihle kidney dollor and xvcnuld avoid the moral qucstioi~of bvbctbcr the clone was being used as a mere means. Furthcrtnore, in the case of solxreone suffering frc3trt leukernia, geiletically defective cels causing the disease cotrld he extracted and geneticaiiy reprograxnrz?iedzrein culmrt.. They then c o d d be i~~jectcd hack into the affected individual and prodwe normal amounts of white blood ceUs. Here too, tl~iswotrld obviate the need to bring anotl~erhuman being into exisld the moral question of tence for a therapeutic purpose and ' u ~ ~pxcmpt: whctbcr such a persoil wcjuld be treated solely as a ilzeans. It would avoicl any of the moral qrxcstions gcneratccl. Izy the hypotbcdcal clonilzg sccliario raisecl. as a variant of tbc Ayala case. Bccause tbc procedure wcjutd il~volve an atltologous transplant, it would rnir7tit:nize the likellt~oodof rejection by the recipierlt's iurtxxrunc systexn, Still arlother possibiliw of the therapeutic use of doning cells to prodtrce tissues and organs IIIIght involve diseased livers. The teclt~riqtlcof autrdogous l~epatacytetransplantation uses the patient's own liver cells, These cells, h r n portions of liver tissue diseased b y n e or more defectrive genes, could be rcinoved and gclietically modified in culture to rcyair tbc critical geiies. They tbcrl could bc inft~secl.back into the patient's liver, xncrgi~lg with tbc organ and replacing the dckctive hepatacytcs.34 frz xxlany cases, l1o\ve'17er~patiellts sll-fferiz~gfro111 lct~ke~xtid, kidxley disease, or liver failure may he too sick to bellefir: from such a procedlrrc. Clr, the da~x~age to their cells xxray be so extensive that they could xzot be genetically reprogrdmmed At an eartier time, before the onset of sympproduction of replacement tissues or toms, ceUs cotrfd be stored Z'or organs. C)f course, this cvonld assume that t11ey knew they wrt. Likriy ta develop the disease, with the genctic inforindti~nreadily availalzle to tbein. This is not to deiiy that we should procccd cautiously with rcsearch in this arca, give11 the risk of DNA damage to cells stored 61s long periods of tirne. Nerittrthdess, when large n\rlrthcrs of people ilecding wansplants die
because there arc not enough humai'r doi'ror orgAns, clol'ring org~izswould be one way of mccting tbis necd. In late W97, rnolectrlar biologists lecl E-iy Jonnthan Slack created a frog exnl-tryo without a heacl.-i' They achieved diis rcsuSt by ~x~a~iip~Satiitg certain genes in sucll a way as to srrppress develop~l--rentof a tadpole's head, trunk, and t-rrF1,Thisleads one to speculate whetlter the technique could be adaptelf to grokv ltunlan organs such as hearts, krdneys, and livers in an embryoi'ric sac functioi'ri~lgin an artificial womb. If such a technique were to become a reality the11 people needilig organ transplants could have tbeir own custom-xnadc organs grow11 fmm tbeir c3\~1'r clorzed cells. The cmbryos rcstalti~igh m thcse ccfls could bc genctically rc~trogrammccl.to suppress developntent of all parts of the body into which the e~?-tbryoothcrwise wozrld develop, except t;or the needed parts, plus a heart and blood circ-ulation.Tltis also could alleviate the shortage of of-ga~ts far trdnspjancation. Even if one =@led tltat embryos have moral status and that tlteir h r ther developnlent should not be intedered with in any way, gi-o~ringpartial embryos could bypnss legal restrictions and n'roral concerns, Far without the patc~ztial&or a ccrztral nerwus systcrn, these organisins would not technically qualify as embrycjs. Insofiar as human body parts like cells aizd dssues lack xnoral status, genctically manigulatilzg them in the respects f have describecl would xtot be niomlly ol7jectionable. I t vvorxld be ob~ectiondbie only if it resultcd in harmful eEects on persorts in the form of disease or disdbilii~yover the coursc of their lives. In addition, cloning human cells could be useiirl in cori-ect.ing genedc n'rutations in early eml-tryoi'ric cells grolving in culttxre. Consider sickJe-ceU anemia, which is caused by a n'rutatian in an allele of the gene colJing &?r bemoglohin. If gclledc testing sho~vedthdt embrycji'ric cells l ~ this d illutatioi'r, then a normaf. f~~x-rctioi'ring genc that wc~uldensure proper functioning of hellloglobin could bc inserted illto crnbryc~niccells Izy xneal'rs of ;L F * ~ w The H - . DNA of the xtrtclerts of one of the cells then could be irnplanted illto a new entlcleated egg ii-01~1tlie noth her and a new pregnancy coz~ldbegin. ir.3 this way, tile origi~inl~117hry0wn~tldbe replaced by a healthy c h n e of itself, which \\ro~ilddevdop into a healthy human being."'. Althotrgh the newr embryo wotrld be genetically identical to the original, the individual deveioging from tlte genet-jically normal embryi, rotri rid go 011 ta develop a different set of psychological propertics and tbus wtjulcf be a distiltct person. Still, the iaailt issue here is the xnotivation &or cloizi~tg cells or emlzryc~s,which is ta pmvent disease in people 1t-y ilttcrcicrzing gc~ieticallybetitre people come into edt;textce."l:'hc aim is to prevent ilartnf~jl
effects in people 1zy elinlinating tbc gclietic causes of diseases at an early strtgc of ~mby)~cjnic d ~ v e l ~ p m cIt~is~ both t . 1ncdicaUy and nora ally preferable to prevent diseases from occltrri~lgin the first place than to bring people into existerlce wit11 severe diseases arld then trl;' to treat them, especially wllexl treatrxrerlts are not very eEective.
Eugenics Again? I h ~ v ebeen arguixig t h ~ in t gcr~cralcloru~~tg should be used, 11ot ta create illorc people, but to i ~ ~ a eesting kc people healtby. It would do this Izy preveriting, controlling, or curixig these disexses or by regencradng tiss~lesand organs daxrraged by degexlcrative diseases.To the extent didt: it is both xx~cdically ar~clrr~orallyxxlore dcceptnble to achieve this air11 by cloxling body beings, there are strc3rlger reasotls for parts rntlier tlinn ftdl-fledged htl~x~dn supparting research on the first type and weaker reasons f i r supporting research on the second, Even here, though, one might ask cvhether at a deeper level the cloiling o f cells, tissues, and organs would be motit~atedby tbc desire ta inlprc~vethe burnail species and thus serve eugeIUc goals. If so, the11 would tbcrc not be illoral grc3unclis Ec3r banning all for1-r.l~of clonil~tg? tfefore responding to this point, it is imporcarlt ta dislingiich it h m Eisexlberg?~point al-tout the loxlg-terxxt evolrxtionnry irrrpact of clo1lix2g.Tl1e idea that clorling rr~igiitbe tlscd to improve die httrnan species conflicts with Eisenberg's claim that it w u l d have precisely the opposite eEect. It would reduce genetic diversiw anif t h e ~ b yadversely aKect the species' ability to adapt to and survive in changing physical environn~ents.Yet Eiscriberg's claim pertains explicitly to tbc effects 011 the burnail species and inlplicidy ta tbc eEects oil i~ldividudlpeople who 1viB exist in the distant filture. In contrast, clainls about eugc~iicspertail1 to people who already exist or will exist in the near future.This is not ta dirrtir-zish the sig11if;icance of h e evcllut-jnnaq ixnpact of cloning. FStrt the point about the etlgeriics of clorlirlg is generntcd by more imn-~ediatccorlccrn about the welfdr-c o f people who alxaily exist or will exist in the near iirture, There are no moral grounds &?r banning all &?rms of clonit~gif we restate the distinction betkveen positive anif negative eugenics drawn. and discussed in chdptcr 3 and place clonil~tgin tbc secolld catcgov. That is, if we use cloning to pr~31notchealth by preventing or c~)ntrc)llii~g disease, rrither tban ta rriise physical and i ~ ~ e n t capacities al alzcwe tbc bascliiie of normal ftrlnctioning, then there is nothing lrtorally c~bjection~b1.e iibout the
procedure. IkcAectil~tgon the alfegcd eugenic aspects of clonil~g,Leon Eass says that "we dc:, ii~tdecdalready practice negative cugei~icseiicction, thmtrgh genetic scree~lingancl prtlnntdi diagl~osic.Yetour practices are gcwernecl by a norlxr of l~eaith."""'ass goes on to digerentiate hedjth prornotion h m galetic enhnnccrxrent, sttggegkig tbnt while the latter is ~xrorally ur-?justifiable,the foormer is not only justifiaMe but obligatory Wo~revei-,he also sqgests that the line between normal physical and mental functioning and pbysical and ment-al enhancement cannot always be clearly dmwn,The difference bettvceii thc twtj is o i ~ l yof cliegrce, ~vhichis oiie reasctn why clonil~gshould be banned. Hc>w can 1\7e be so sure tbat a clonillg program intclided as a forin of ~~egative et~genicsw o d d rlot evolve into a pmgrala of posit-ivc: ctrgenicsi E3ecazlse the ifiEerent fortns of clorling tvotrd be arrdnged along a spectruxxr of cases of the same kincl, if one case tvere perxnittcd, tllexl it could set a pecedent for and cause other cases to be permitted. And because these other illstances cvould involve n~ot-alXyrepugnant " h a v e New World" scel~arios,cloning should not be pernGtted in the first place. C)r so one i ~ i g h targue. It appears t h ~ tbe t spectcr of the sliitpery slope oncc again has reared its ugly head. Yet, as I demolistrated in chapter 3, tbe slippery-slope argzinerit adis trr~sorrr~cl becatrse it vanced in respoxlsc to various uses of 17iotechrloloC~ rests 0x1 the fallacy of assirxrifatioxl nncS on trxlwarranted clairxrs nbout catrsation. Although the salnc gerlemi tcrtn is used in both brms, posirive and negatit~eeugenics do not di&r merely in degree, but in kind. Each kind rests on a meiiicnlly and morally LJ.istinct-ranonate. In negative eugenics, the aini is to prevent, control, or cure disease in people a r ~ dthereby raise them ta or xnaintailz tbcln at aii absolute baselil~teof iiormal physical and mental functic>iiixig.In positive cugeics, the aim is to raise thc level of functioning in people who are not discdsecl. above the baseline.There Inay be rcladve differences in degree of disease or health below or above die 17aselirle. Rut the baseIirle itself is arl absolrxte xxleasure that d i s t i ~ ~ g ~ i s between hes disease ailcl health, as wefX as the airxrs of treatrxrerzt and cxlllzzncerncnt. Xt does not admit ofdegi-ees. If this is corrt.ct, and they are co~~cepttrally distinct, then negative eugenics. is not assiniilable to posttitit. eugenics, O n e does not cause or inevitably lead to the othel; and therefore we sho~ildreject ally appeals ta tbe slippe~)8-slopearhwiIlent to prc>viclereasoils for bannixig human clonillg. The alleged slide from negative to positive eugci~iccloiiixig llecd not occur.We car1 brlxrulate prtl-tlic poficy and erlact Icgisjdtion that uphoids a
clear disdncdon bcbveen proi~~oting healtb ta a level of r-rormal functioning, 011 thc oize hai~d,and enhancilig people's cayacitics alztwe this level, on the other."l-'lieseare distinct aims generated by competely digertlnt sets of reasoris correspor~dingto heneficexice arid pcdkctioi~ism.A sixnilar poficy works quite well in E%ritain,where there is a genernily respected regulatory authority tltat oversees IVT",hunlan eml-tryo, aild stem cell research. PI-ovided that tlte ratlollale for clonit~gis clearly spelled out at the policy level in terms of health promotim through disease prevention, there is no reason to bclieve tbat cloiling ~vctuldiiievitallly lead to an ciibancerncnt program thdt wt3~1ldmake sctme people u116airly better off th'311 otbcrs, or that it xnigbt adversely atreet our humanity
Conclusion The possiblliw of cloning human cells, nssues, organs, and perhaps even full-fie&ed humail beings oRers great opportuilities f i r preventing, coiltrolling, and curing genedcally caused diseases. Although it still may be a rcrnotc biologcdl possibiliy, the xnc)ral in~plicationsof cloni~lgl~tzinanorgaisms tbat would dcvclop into persoi~sr ~ ~ a kusc well-acf-visecl. to proceed caudously on this front. For if we clone humans solely for the purpaw of ~ r t k i n ggellaic replicas of ourselves, to repiace a dj~irlgpcrsol.1, or as a sotirce of stern cells or hone marx-OIVto rave ariother person's life, then the prnctice w d d violate a f~indatl:tet:ira1 rnordl priticiple,l"be clone would be used solely as a nleans and not also as an end, in which case clonir-rg wotrld be n~arallyobjectionable, It is in this xspcct tltat cloiling cvould undern ~ i n eone's atztanonly, dignity; aild humanity Nexrtheless, clonillg does not ncccssarily iniply such a conseytlcnce, sincc cloi~esxnay very well be trcatccl. as er~dsand not J~zstas means. So there is nothii~tgirlhcrci~tly r~~orally objectioi~alzlealzout cloni~zgitself. Tbc r ~ ~ o rissues al pertain ta the ways in which clox~ixlgis used. Clot:iing should be lxtedicdily arid 1rtoraX1y perrrtissiblc when it is r31ot-i~*ated by and used far tberapczitic goaJs.Yet, to the extent that cells car1 be genetically reprogramn~edto produce genetically ideiltical but healthy l d copies of diseased tissues and organs, tlte cases in mrhich there m ~ ~ he con~pellingmedical or moral reasons to clone human beings would be rare. Indeed, this prrictice wctuld h'3v.c thc virtue of siclesteppi~igthe xnost trt3txblcsoine moral questions gencratcd by clanirig. C:loning cells, ernbrycts, or organs to replace diseased body parts 1%7ouldbc either r~~orally pernlissihle or morally rieutrral, sirlce tliese parts have rio moral status of
tbeir own, Nor wtjuld clo~~ixig tbreatcn our persorlhood or l-tersonal icientity, because persorls arc constituted by but are not icientical to thcir body parts, Genetic identiw is; tlot p e r s o d iclcnti~;unlike cells, selves cannot he cloned. I1ersolzhood and persollnl identiry are not sin-tply tii~lcrionsof tisstxes, orgntls, or genes. Provided that it is consistent witl.1 the idea of negative euge~iics,of promoting health by preventing and treating disease, cloiiing can he a morally justifiable form of genetic t e c h n o l o ~that accords with our deepest metaphysical and moral convictions abor~tthe nature of persons and the value of our lives. Asstlr~Gngt h t ~the Kantiai-2ix~jrxnctic>~~ ta treat clones not solely as mca~ls but also as erids IS upheld, there arc orlly tvvc3 morally ot3jectiondble aspects of clo11111g.The first is that the procedure might entail 1)NA darxtage to cell ~lvclci,which in tltrn cotllif lead to prernattrre aging and disease iri people who have been cloned.The secold is that, as an asexual for~rtof repi-odtrctian pi-acticed on a broad scale, it might entail long-tern1 adverse effects on genetic dib~ersityand tlte survival capacity of tlte human species. Althotrgh this sceliario may not be likely; nlany people might avail themselves of it to i ~ i i l i n i z ctheir children's s~sceptibilityto disease. It could have adverse intcrgcnerationd1 effects by Increasing the n u r ~ ~ b of e r gc~letic 111uti1tions within Fa~~ilies. A111ong otber t h i ~ i g it, raises the questioll of weighing the p t e ~ l t i a lbenefits of-ciollitlg and otlier fartns of geiletic Ixta~~ipulacicri~ and tmtlsfer betkveen people who exist 11o~vancl in the near fixture agi~instthe pote~ltiafharms to people xvho will exist in the distant fixttxre. This n~oralweighing is necessary because nranipulating gencs cotrld adversely affect genetic dib~ersity,the result of which could be a higher inc i k n c e of deieteriotls mutations causing a higher incidence of disease and t siniilars questions is death earlier ill people's lives. A~lotberIsstlc t h ~ raises tbe pasibility. of gclietically ~ n a i p u l a t i ~ the i g i~~echanisms of agi~lgto extend thc h u r ~ ~ alife n span. It is Iniportant now to exallline the evolutic>~.rary hiologi~dfactors irivc)i\red in altering genes for ellis purpox, as well as the ~xtetaphysicaland mora1 co~~sequei~ces o f it for both prc"ii~t and fircure people.
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trl the p ~ c e d i n gbtrr chapters, I have exn~nineddifit-ent types of ge~letic it~tervel.ltiotland have explored their irnplicdtions fclr the existe~lccand lives of k t u r e people along biological, ~netaphysicni,and ~nol-ralditnensioi-2~. My aim in tlrus chapter is to iirrther elaborate these issues along these same dinlensions, payilzg special attention to tlte possihdity of controliing the genetic mechanisms of agng and extending the lengh of the l t t ~ n ~ a n life span,Tbe discussioi~1 \ 7 d f~lrthcrelucichtc the i~npactof gclietic intcrverition 01-2 the bdlancc bcm7cen acutc and chrc>i.ricdiseases, persa~~at, idcntity through time, and o u r obligations to future generations. Clver tlie 1 s t littndred years, the derielqe"1orld has expcrier2ct.d a substa~ltinldecline in rnormliey and a corresponding illcreae in life exp e c ~ n c Tlzis y is dlle IargeZy to the epinemiologicnl shift from the predornilzance of acute inkctior~sdiseases eartier in life to cltroi~icdegenerative diseases later in life.1 Nevertheless, even if tlte nlost con~moncauses of were elinlix-rated,the increase ixz death-cancer, heart disease, and stro life expeceincy would bc no rllorc tbal-2 about fifeecri years. Morec>ver,although the nvt.rage length of life ((fifec x p e c ~ i ~ ~ in c y dcvelopecl. ) counties bds steadily i1icreas~d,the I ! Z Q X ~ ~ T Eduratio1-2 ZI~E of lift ((fifespan) bds not. Cel2tnries ago, few people lived 100 years, and today this limit rerl~aitzs iilndanle11taIl.y ttnchnnged. 'l'here arc rnore ce~lter:lariarlstoclay, h t ~ tthey constirrrte a very srnali percenk2ge of the bun- an popdarion. One of tlte essential biological properties of humans is senescence, tlte process by wltich cells, tisstles, and organs gradually deteriorate as we age. This biologicai aging entails the decreasing ability of malecuhr mechanislns to prc3perly 111aintai11 cc11 fuiiction, Agilig is a11 ix~~scdpal~le Eict of o u r biological lives and has different explai~ations.As I notccl. in ch'jptcr 4 with respect to tbc I-Sayack limit, one expiiandtion is that cc& f o l l c ~a ~ strict genetic pmgrarn and divide only a certnir~nt~rllherof times before
dying. Ailotbcr account, also noted in chdptcr 4, is tbat over t i n ~ ernutatiol'rs accurnulatc in cclls and adversely affect the r~~echanisms c~)ntr~llil~tg c e l maintei~anceand repair.lkt another expalatior~is tltat wlrestricted caloric intake affects glucose tnetabolisn-I in suclr a way as to incl-ease the p m d n c t i o ~of~ ii-ee radicals, wllidl in turn dd~nagecells.Tlzere is no single accorlnt of aging because it is governed by rnal~ydi&rent genes and mo1ecular processes. But all of tltese processet; involve senescence, Except f i r a sn~allnunll-ter of individuals, senescence enstlres that ltunlans cannot survive xntlch b c y ~ n d100 years. Although we have not asccrtailicd all of the biological gactors in aging, it is worth cor~sidcringtbc role of telt.>meresin tbls process in the light of recent genetic research. As der-crihcd in chapter 4, telolncrczs are the erlcls of ctimt.l?iosomes consisting of I-epentifli=I)NA sequellces that control the nunll-ter of cell divisions arlcl becoxnc increasix~glyshorter the xnore tiales cells divide, The telomerase gene is repressed in nlost somatic cells. In two sepwate experinlents, however, researchers have discovered two ways to extend telomerase expl-ession in these cells. C)ne gmup was able to insert a copy of ail active harm of the tclomcrase genc into certailz cell types and exterid tbcir life spar1 in culture by at least twe1it)r divisi~nsbeyc.>i'rdthe Hayflick limit." difZ:ert.nt group was able to rrconstitute l~tirllanetl-tbryonic stem (ES) cells, tvIiicIl are undiEerentiatecl ard have perxxranently yozrthf~iltelorncrt.s."~n theory, cculttrmd ES cells could be generically programmed arld gtridcd into targeted tiss~resand organs to re_luverlate them, This corlld delay the onset of or ameliorate such age-refated diseases as arthritis and diabetes. Morec3ver, if inserdan of telomerase-active genes cotrld make cells inlnlune to tlte molecular clock that triggers senescence, and the lik of cells were extendecl. illdefinitely then it r ~ i g h bc t possible to extend the human life span another 50 to 100 years,Thcsc arc rough figures without any intrillsic v.aluc-.Tbepoint is siniply to use them as references f i r reflecting or1 the biological ancl r~~oriil issues gerierdted by the idea of a life span possibly twice the let:lgh of the present 1lorrl.r. The idea of getzeticslly marlipulatirlg the xx~echarlisxnsof aging raises the &32lowing yuestians. If it became possible to extend the lik spatz of our cells and bodies, tlten what would the n'rotivation be for doing so? Would we w n t to maintain adult vigor &3r a longer period of time and delay tlte oilset of o r ar~~eliorate the phy"i"d ccctnditions eritailed by seriescencc? Would we, ill addition, want ta exploit tbc tcchnolo~yin order to live r ~ ~ u lorlgcr ch th'm we presently do? If 011e answerccl. the bst qrxestion affir1ztative1~ then one would cZo weil to consider tlie i ~ ~ ~ p l i c a t i oofn sdie
prospect ofa significantly loi~gcrlife spa11 &or one's icientiv and the qtxality of one's life. Equally inlportant, one 1\7oul.d do 1\7ell to consicier the. effects e the qualthat extendi~tgour lives in the present genemion r ~ ~ i g lh~t v on ity of tlie lives of tlie people wlio will exist in the rxxt and srlcceedir~g generations,We need to reflect 011 what our obligations to them zx~ighl-be and wltat these would meall for the life-extending genetic interventioi~s cve nlight decide to undertake in tlte present generation. Some remarks on the current prrblic debate on enlbryonic stem cells are in order. While ES cells could be derived from cloned embryc:,~,presently tbey are mined from IVF cmbryc:,s that have been discarded by fertdiv clinics. In Augzst 2001, President Bush announcecl. tbat be 1\7ould allo~cv federnl f~ix~dix~g for lirllitecl stem cell research. This vvorrld involve existix~g stem cell lines fic~rnetxrbrj~osthat already had been discarcjed. No new ernbryos would be prodzrced to generntc additiond stern cell lines. The main moral issue here is cveighing the value of aflosving an embryo to develop into a full-fledged ltuxr~anorganisnl and person agait~stcreadng (and then destroying) it for 1-esearch tltat could lead tr:, treatnlent ofdegenerative diseases in cxisd~igpeople. We cannot bcriefit an emlzryc:, by allowing it ta develop into a person because 1\7c d c ~not thcrcly make the cmbryc) bctrcr off. Eznbrycts do not bccome penon" at lca"tot in the identiq-cSeterrir1ii1i11g sense of ""bco~rte." To insist othemise is to cot~ttlate persons and Irrrtrta~~ orpraisl-m, whidi are distitlct ontological types. Rut we may he able to benefit people suffering froll-t degenerative diseases by using ES cells to treat tltese conc2itions. We can make elczsting people better o E by deviating their pain, dsahilit?;, and sagering. We have a strnnger moral obligation to eistit-tg people than to merely potentidl people (embryos). Thcsc rcxsons wc3uld seem tc:, Justify using h u l n a ~ES ~ cells fcrr i~ledicalresearch and possible treat~ncnt.Yct, xnaq belicvc that emlzryc:,~ and persoi~ssuiFering fr01n disease have cqrxal moral. vdlue. The moral isnres could be sidestepped by usitlg adtllt stetl-t celfs from tlie skin, fizr example, mtber than from embrps. But tldike tliese other cell types, ES cells are totipotex~tancS therefore rllore versatile. So the debate on diis issue is likely to continue. for sonle time. The. issues tltat I am addressing in tltis chapter nlay not appear to be. as as the moral status of the spare or cloned embryos immediately pressi~~g from w h c h ES cells arc derived. Rut the idea of extending tbc hrzman life span through gclietic illcans ~ ~ e c to d sbe addressed. For the intcrcsts of distant filture people arc no less xnorally sigificant than tbc interests of those of us living in the present ancS xlear fzztrtre.
C:onsistent with the p r e c c d i ~ ~chapters, g the biological framc\vork withill 1\7bich I will address these r~~etaphysic~l and xnoral qrxcstions will be one ix~forxrredby evolrxtionary bioloti,yYInsofar as x-ranrml selectiox~deterlztineii the genetic n~echarlismsthat corltt-csl the lik cycle of cdls, them may be a good e'l7olrttioxzary explanadon for serlescerlce and death at the ex-rcS of a limited life span. Natural selection allows for genetic mutations that cause disease later in life but keeps these mutations to a m i n i m m eadier in life.The asymmetry in the way these mutations are selected oKers a net reproductive advancige to human organisms so that they can transllvt their genes to oi5pring. 13elctcrious mutations in tbc past-reprc>d~zctivcperiod arc not selectccl. against because they do not affect rcprc~ductivcfitness.Yet nrhstnntialty extencling ollr biological lik spm tllmugh the insertiorl of gelleticzzlly r~lodifxed telonnerase into, o r r e c ( t i i o of ES cells at, the gerrn line could alter the cotlrse of natural selecdotl, itlcl-ease the nurnber of deleterious nlutations in humans earlier in life, and result in harm to &scant humans by mahng them more susceptible to PI-ematurt"disease and nlarcality. I will explore how genetic intervention i ~ ~ v o l v i tclomcrase-active ~lg ES cclls could alter the ratio of I-zic>logicalbcriefits earlier in life to biological burderis latcr in the life of hrzxnan org~rusms.If this rado were reversed, then extending the llillrrarl life spdr-r well b e p n d the rough present lirnit of I00 years could mean that p o g l e existi~lgin the distnnt f u t ~ ~w r e d d have shorter and rnore diseased lives o~tvingto a higher i~lcidenceof genetic mutations eadier in life. These people cor~ldbe harmed hy the defeat of their intexst in eslsting mritbout l7remntable eal-ly-onset infectious cjjseases and the opportunity for a decent 1IUninlum level of .vveU-being over the course of a reasonably long life. Adnittcdly, this is a possible scenario, and as such does not warrant the strongcr claini that all rcsearch ain~ecl.at ext c ~ ~ d i nthe g h u i ~ ~ alife n span should be foreclosed. Indeed, it would be in?plausible to make stzch a claim. k r this research cnufd lead to treatx1tet:lts for rlla11y degenerative diseases. R,zther, I arn xx~akixlgtile weaker cldixn that, if one accepts the pri~lcipiesof e'17oIrttioxlary bialo%q,the11 the possibility that I anr raising should at least give us pause before we try to develop m d implement life-extending tecbnolof;). on a broad scale. 111 addition to the moral reasons I have just adciuced, there are prudendal reasolls agdi~lstgclieticdlly manigulatil~tgthe xnechanisins of a p n g to substrtl~tiallyextend the h u i ~ ~ alife n span. I will arhwe that a substantial increase in longevity. wc3tald entail undcsiralzle conseyucriccs for personat, identity. and the rationdj, grcz~lrldsbr prtldential concerll about orrr t;lrt~treseZws, A
loi~gcrbic>logical life of a htrma1.r organism would not lleccssarijfy iinpiiy a correspar~dingconti~~tuotrs and u~lificdpsychological life cof one and the sarnc person. The point is not that a virtrrally immortal life of 200 years vvotlld be had br us ns indiviclrrals, hut that it would not he prudentially desirable, because of its effects on personal identiv.Y,t, if it xvodd rmt be desimble, then tl~erewould be no p o d zclason for each of us to have a substalltially longer life than we presently do,
Cells and Senescence
tr is ir~structiveto place the process of ceZl set:let;cet:lceand its eEects on tiswet; and organs withit-r the broader ii-amework of the lrun-rar~in-tntune systern,We become more strsceptible CO diseclse ns we age because cells di-iride only n finite x-rrxxxrber of times arid becatrse die tznderlyi~~g xx~cchanisxnsdiat control cell damagcz and repair no longer function as efficiently and effeetively as they did earlier in our biological lives. Apoptosi" or pl-agrammed cell death, is one factor that maintains eqndihrium in the immune Whereas tbe gradual shortci~il~tg of tclo~aeresand thc nulnbcr of cell divisioi~sis 1\7ritten illto cells from thc pcjixit of COIICCP~~O~I, apcjptasis is initiated in response to D N A damage airccting critical gcncs that control ceU gl-oxvth and pmlifet-atior.1. Apoptosis is necessar-). to 1rtaitlr;3itlthe delicate halmce in the imrnurze systetrt k t w e e t : ~cell gmwtl~and ctatrtage repair to [:)M, xvhicl~is crucial to the nrrvivz11 of the orgdrlisrn.l'bo little npoptosis nlay lead to cancer and autoin~nlunediseases like rheurr~atoirliarthrids; too much may- result in stroke damage and neurodegenerativt" diseases like Alzheirner's.C3 In~mtlnologicalho~aeostasisis maintainccl. by prc>tcin~h'jtsscr~seD N A da~aagefrom ioi~izil~tg radiation, oxidation, or che~aotherapctrticdrugs. These proteins aiFect tbe cell cycle in eitbcr of two 1\7;lys: (2) stoppixlg cell divisiot.1so that I)NA dan~agecan he repaired by the appropriate mecha~-risr~-rs; or (2) deciding that the dantage has g m e too far ancl that the celf ~rtustctie."l:'he tulrtor mlpprtlssor gene p33 is critical to the first mecharlism in that it suppl-esses cell proliferation. If this respoilse is wei-ridden by oncogenes causing somatic-cell nlutations, then the death-inducing protein tunnor necrosis factor (TNF) is activated and catzses the cell tr:, die be&ore it demlops ta tbc point of c~)nstitt~til~tg a ne~plasticrisk. C3rdiliardy9 when there is dalnagc ta DNA, thc dcrebwlatcd expressioi~of doGnant orlcogcnes thdt induce cell proliferation, such as Myc, El-A, and E2F, is offiset by the activatioxl of p53 in msponse to D N A instlft, as well as by key
regulators of the cell cycle likc tbc rctinoblblastaiaa protein (plkb) . When tbcse rehwlatirzg Factors are ovcrricldcii by oi.rcogeiies, al-taptosis (through activation of TNF) puts a stop to fizrther deleterious proliferation. If a p p tosis is eEective, then the oncoproteins 1 fiave mentioned m y indirectly act as trunor suppressors even tvhen p53 has been activated. These katures of tlte immune 1-esponsecollstitutc one way of ensuring that cells divide at a certairl rate over a certaiti period oftinle. It is important to enlphasize the connection betmreen cell senescence arid apoptosis in the i1nmunc: response. I lzserting ES cells or manipulatir~tg gencs to extcrid thc period of tclomcrase expression iri sctmatic cells could retard senescence and the onset of agc-related diseases. It also could rejrx~*7enate dairtagecf tissues. Al the sarne time, however, there i s the risk that, by ~~etltralizing or eli~rtirlatingone of tfic controls on norlrtaj cell serlesccnce, the altered cells could becarne canccrorrs. f3aradoxicalIy, a type of ger~etic intervention intellded to extent2 the lives of cells and thereby extenc2 adult vigor and the lengh of the human lifc span ultinlately could, turn out to shorten it, In~mortalizingcells is a double-edged sword. To comyltcatte rllatters further, not all cell types arc eqtlally sensitive to 13NA insult or the functic>i~ of telomerase. So it is uiiclcar which cells tvould be Inore likely to respond ta an active &>rrl~ of tbc tclolnerase genc ill the desirccl. way and which cells vvorrld be xxtore likely ta proliferate orrt of car~trolarlcl e\reIztrxally kilt us, In addition, if the i~lwstmentthat gerlcts make in htundn reproduction comes at the expense of cell maintenarlce ancl mp"ir, then, in tfte case of cvonlcn w h o have borne children, it in unclear whether a telo mel-ase gene in combination with ES ceUs could nentrrtlize the effeet-s of repmducti.oi~on cells and retad sellescellce in tltem. lkcsearcbers have reported that, 111 expcrilnents performed or1 mice, tclomcrasc-ini~z~ortaIizirig cells did not show any cbroinosctmat. chLjngcs. Morectvcr, cmii after m70 key grcjwth suppressor genes, p53 and pltb, were actiwted, they did not iind any calzcer cells.' This sttggests that crucial checkpoitzts or1 growth ancf prolikmtion are s d i i r z ~ c in t tliese cells.To be sure, one cannot trtalce the simple inferetzcc that, because the experinterlts yielded these results ixz mice, tltey would yield the same results ixz ltuxr~ans, But even if we could, have our cake anif eat it too by retarding or even reversing the effects of senescence without simultaneously increasing the l g a form of gcrisk of cancer, there may be reasons against u n d e r ~ i k i ~such netic interwiltion to lengtbcii the humari life spa11 well beyc~ndtbe present norm,
Rccatrse the tclomerasc gene is activated in ~~ldiffereiiti;~tted ES cells, tbcse cclls can divide i~idcGnitcly,prc~vidcdthat tbcy remain crs~bryc~ruc. Clnly ES cels car1 rc~rrainz~ncli.CTerei-rtiated a r ~ dtotipotent. As the crxrbryc3 develops into a fetus a i d e'17exitualiy into the body and brain of a fullfledged hzrxrta~iorg;~riisrn,stern cells dit-fe~ntiateinto the specialized cells necessary far tlie structul-e. and contin-tred function of the body's tissues and organs. The telomerase gene is expressed in undidtoerentlated cells, but it becomes repxssed once &Eerentiatioi occurs. Still, there is considerable variation among cells types. Braill and heart cells, for example, stop dividing o i ~ c ctbc orgdnisin is EtiUy developed. In contrast, skin and k?lt10d cells coi~ti~sue dividing and can bc rejuvciiatcd by stcln cells specifically ~irgctcd to these celt types. Clnce these types have differeritiared, thotrgh, their celts have a fix-zitc life span, dividing only a lirxrited x-ruxxrber of tirrres and e'I7eI-rtrxally Mfing prey to senescellce. h ~ a tparticular type of stem ceU, present before en~bryonicdevelopment begins, can resist diff'e~ntiationand the lifetrime limit that this entails.These eml-tryonic germ ceUs migrate to tlte developing ovary or testis, whcrc they gclleratc tbc egg or sperm for the next generation, By isolatilig tbcse cclls and nlaki~lgthem inii~~trnc ta difTerciitiatioa, researchers could ensure that the cells rctainccl. permanently yc~utbfuland active t~lt~~nereti. If these ES cells with the active tctomerase gene could be guided to carefray contmiled specif c pathways of digerctlitiatiotb then it r ~ ~ i gbe h t possible to i5in-rtrtortalize" the speciajized cells of the blood, heart, and odier orgz~ns, There are weaker and stronger biological interpretations of "i~nzmort:rl.'" Neither of these interpretations should be taken literdlly, since neither imdies that our lives can be eternal. Furthermore, these i~lterpretationsof in~mortalityshould bc disti~sguishedfrom tbc sense in which cancer cells ~il, eridlessly out of control to bring about tbc demise arc i n ~ r s ~ o r divicling of huis~anorginisms. According ta the weaker sense of cell in~mortalization, genedcdly produced telonreres, or specially r~~odiiied ES cells, could be ir-ztrc3duced into soxrratic-cell types, Tllis co~xldxxraderntely retard the process of senescence by rejtlver-rntiiig cells, tissues, a d organs and exteriding the period of '~drrltvigar anotlter ten to twenty years. I have referred to this as "I-egenerative n~edicine,"Accardingtr:, the stronger sense of ceU imn~ortaliza tian, undiEerentiated. telonlerase-ac tive ES cells, cvlticlt are functionaUy eqt~iviilentto germ cclls, could bc prc>grars~rs~ed into the germ lilic at an early stage of cmbryc~i~ic developlnc~itand gwictcd illto a13 cell types. Thus, even after differentiatilig and forrrung specific tlsstlcs and orgins, aU the body's cells could coi-rtixirte dividing ixi a yotrthftil state for ax-r illdefi-
nite perirrd of tin~e.Tbisiiight ii~akcit passible for the hrzman life span to be extended up ta between 150 and 200 years. O f course, a lorzgcr life wotlld be desiral-tle provided that it did not incltrde the physical, cogl~itive, and agective inhrlxrities orcfinarily er~taiSecSby aging, which the sort of Renetic interve~~tion in qtle~Ciot7presllirllably would p r e v t " ~ ~ , In maily respects, there is no siglificant bidogical difference b e ~ e e n extending the period of telomerase expression in somatic cells and many n~edicalix-rtermntions ctirrendy ix-r use. But each of these intermntions allo~cvsat most a ~norrlvrafcextension of rrjugbly tcii to m7clity. years in the hu111an life span, where tbc aim is not so xnrzch to increase the ~zumbcroflifc years as ta col~trcjldiseases and xnaintaili vigor for a longer perirrd. A substarltii41 exterlsiorl of 50 to 100 .)rears of the life span worrld be sigrrifica~ltly different froxrr currelit rlledical ir-zte~ventiox~s becatzse it corrld ix~volvea life span t'~vicethe length of the present x-ronrr,Also, this cxter~siox~ tvould be n~odvatednot just by the desire to remain healtl~ylonger, but also by t l ~ e deeper conviction that there is intrinsic valtle in livixlg much longer than cve presently do, given that being alive itself is intrinsically valuable. Ncvcrtbclcss, evolutionary biological rcasolzs exist for not substantially extendilig our lives through ge~zeticmanipufatio11 of tbc xnechanisins of aplig. And tbcse bic3logical reasons could ilzfluence ii~oralreasolzs regarding how we should respect the i~lterestsof firturn people in not being harmed."l-'inkeringwith genes at the gcrtn line to extend life spans by Kducing the incidence of genetic mutations later in life ~rtight:gradtaly alter the cotrrse of i~aturalselection. Such n~anip~~lation nlight ix-rcrease t l ~ e inciknce of mubtions earlier in lik and hence the incidence of early-onset diseases in ftrture people. Those who experience the initial effects of tbis type of iliterventioi~in the preserit arzd ncar future iiight bcneGt 6c3m it by hLjvi~ig lol~gerand healthier lives. But pe013le who will exist in the distant future could bc harii~edby a ""rcdrcsscci'~cnetic balance ilivrrlving a liigller incidence of deleterious ~ntltcttionsearlier in life. Conseqtlex~tly i'iitrrre people could be atWicted with a higher i~~cidence of p r e t r t a m disease and nlortaliq in dieir lives, which could be considerably shorter diaxz, otrr own. Eve11 if natural selection cotrld correct itself and limit the ilunlber of mutations, this pmces o p e n t e u t a glacial pace. Before a corrcctioil occrirred, iilany people could bc harmed by the defeat of their interest in having the same reasol~alzlylong life spa11 tbat we presently crijoy. Insofar as we in the present gcncration have an otlligation to prcvcrzt harm to peaple in distaxlt tiiture f~eneratiolls,and that extending our owl1 lives thmrrgl~
gclietic manipulation of cells could bar111 tbcsc people ill the respects I have described, we should carchlly think tbrc~ugbthe iniplic~tionsof this teclino1o~;)rbefore deciding whethe? or to what extent, we shodd exploit it.
h Evolutionary Trade-O@ Agiiig itself is not a disease, But the diseases resulting fiam the gradual deterioration of the gro.r;trtl~-and-repairmechanisms a f cells are part a f an age-related prc>ccss.("r~ieralfy,tbcse 1vill l3e chrc)iiic disorders of ~luddleto-late adulthood. Gencs h'3v.e different allelcs, and alfeles h'3v.e diiTercnt functic>~.rs,The same gclies with allclcs tbat i m k ~ ~ U I ~ organis~ns I I susccptibie to iate-o~lsctdiseases also have afleies that protect us frmrt early-onset diseases to enszlrc, that we xvilj suwive long enough to reach reproductive age. This idea rests on the pleiotrupic-gene hypotlsesis (which I will explain shortly). The disparate iiriictioiis of alleles are part of oiie e d u t i o n ary ptrryase, which is enstiring that genes will be transnlitted illta the next generation. Since the most common way to tJo this is through sexual rerril detcrr~i~les thdt gclies work ta cribal~ccthe production, ~ ~ d t ~ sclecti~n s~rTbivalprcjspects of 0rgd111sins until these organisms have reached reyrodt~ctiveage. Natural selectic>nacca11113lisbcs this l3-y liniti~igtbc nuinbcr of deleteriotis tntrbtions that would nlake orgi~nisntssttsceptihle to diseases t h ~ j u g hreproductive age. Clnce the reproductive period dlrrixlg which genes wotild be tratlsr~littedinto the rxxt generatio11 has passed, the survival and repi-ciductive fitness of the organism have diminished importance. So natural selection cvrU allow an increase in the nurr1be.r of mutations leadit~gtr:, a 11igl-te.r susceptibdtty tr:, disease, Natural selection m,rxilnizes the survival proqpects of genes, not the health of huinan org~nismsor thc 1%7cll-lzeingof persons. Nevertheless, bccause the hcaltl~of human orgdnisins is infucriccd l3-y the ways in which genes control the cellular &actions underlyitlg physical and ~rteilt-alhedth, uttlirlz gelles (or alleles) are selected will inflzreilctz the health of lru~natlorg a n i s t ~and ~ ~the well--hging of persotls, Thus, alttlough f~eilesand the force of natural selection are impersonal, tl~e):are indirectb person-agecting. The impact of natural selection on humans progressively weakem with i n c ~ a s i n gage, which suggests that genes providing biological benefitis earlier in life xnay e n t d bic31ogical burdens later in liEe..The mecibalic costs of i~~ail~ttail~ting tbc rccylrisite mechanisms for human sunrival and reproductive success i1Iean tbat mutatiol~swith hc3rr1dkleffects on h u r ~ ~ aorgdnisins n in the later stglges of d x i r lives can acculntllate witliin the gene p o d . C-'vex^
thdt survival and rc~>roductive6tiiess arc all tbat lnatter in evolutionary terms, thcrc is no evoltldonary reason far selcctiar~agai~lsti~~utations harmful to hltrnarz orgi~nisrxrswell bcyc>r~cl reproductive age. In the light of this, the question arises as to tvhether nlanipzrlating genes iirr the sake of lot~gevivrnight adversely affect selection agai~lstmtttatior:~in reproductive and pre-rep rocfuctIve years. Hunlan argdnisn-zs have a Iin-zited lifetinle biochemical budget, in the sense that their somat.ic cells divide only a certain number of times. The idea of a gx~titenuinbcr of cell divisions is consistent xvitf?,aU of tbc explanatioi-zs of agixig that I cited at t l ~ coutset of this ch'jptcr. Fcl>llowi~igthe i~~andate of gclles to bc transrruttccl. fro111 one gencradoi-z tc:, the ncxt, cells devote mlliclwf their enerh:1; in dividing to sexual reprod.tlctic:,x-z.Insofar as te of cell divisions ixrrplies that there is a lixrrit to this cnerhTf a f i ~ ~ ix~rt~x~ber it seelxrs to follolv that cells will have less e n e r g to devi>tcto dieir xxraix~tenance and repair in the post-1-epmductiw period, Eve11 if the life cycle of cells corlld be extealded tfiroug1-z genetic manipulation, it is m ~ r t hemphasizing that there is no evolutioilary reason &?r nattxral selectiovr to minii ~ i z ci~~trtations later in life. Manipulatiing genes to do this could alter t l ~ e force of ndtural selection, ir~creasethe incidence of lnrztations earlier in life, and in turn affect the health and eve11 s~rvivalof ~ U L ~ ~ inI Ircprc~d~cS tive and pre-rel~rodrrctiveyears. This coulcl resrtlt beca~zsewe vvottld be char~gix~g what the hrt~x~an body is x~aturallydesigx-zed to do. There may be an evoltrtior.~arytrade-off hetweetz repmductive sttccess and longevity, with resources invested ta ellsure reprocfuctive stlccess conling at the expense af a limited life span. When cells devote mare af their enerLqto sexual repmducdon, they have less e n e r n tr? devote ta nraintenancc and repair ixi the post-reprod~~tive period. Co~~verscly, if cells dcvote more of tbcir encrh7 to ~ndintcnanceand rcpair for the sake of longcvit)r; the11 less enerLT c211 be dcwtecl. ta sexual reproduction, Since repmductive success ellsarres that genes will be t-I-atzsxnittedinto the next generation, it seerlzs that the long life of Fries entails a linzited life spar1 for htzxxrar~s, Keproducti.ve kitlless is a~lritheticalto prenrature disease and morta1it)i in pre-reproductive and repmducdve years, sitice diseases during these periads make it less likely that a hunlan organisxr-zwill survive up to the time whcri it can reproduce. Thc diseases in qrxestion arc ixzfectious ixi ctiolohy9 rcsultilig from invdding bacterial, viral, and other pathagcns.These IncltdcIc such maladies as tuhcrculosis and HIV-AILIS. Because these conditions arc causecl by pathogens and art. potentidily lethal, I do nor: incltrde the inabil-
ity to reproduce in the salnc class of diseases, if indeed this could be considcrccl. a disease at aU. In the rezmote p a t , genes did not have to invest mucll it1 CCII ~rraitltenance and repair because tiur~~an orga~lisxrtsdid not live much beyond reprdrrctive age. All the hic7chernicaZ energT went- illto prolnotitlg repmLJuctive fitness, and cell mechanisms were p a r t o f the immune system's purpox to protect bun~atzsfrom pathogens and 'warantee their survival so that they corlld repmduce. A =cent study has shown that fernate longevit~j is negatively correlated tvitb nulnbcr of progeny and positively correlated with age at first childbirth, As the case of a cklcilfess wctman (jeannc: CMi ~ ~ e nint ) FI-mce wbo died rccently at age 122 III~~strat~s, a t\7oma~ris Inore likely to live longer the felvcr (ifany) clliildt'~"xl she hedrs at a later age.Tlzis nipports the idea of an evalutiorlary trdde-ofa'beavcet:~reproductive success and l o x ~ g e v i ~ Suppose that sonlehow we could nlanipl~lategenes so that they cotrld enltance reproductive ftt~~ess a d extend the human lik span. We ' u ~ u l d tJo this by limicing tltc il~ci~leni'e of mutations in hot11 earlier and latcr stages of life. If tbis were possible, t l ~ e na loirger life for present and near future people wt:,uld not be incoi1113atiMe with thc s~rvivaland reprc~ductivcsucev~ryc)i~e wc:,uld benefit and no cess of diseint future people. Pres~~iaal?ly, one worxld be hzlrxrred. Rut diese cor~clrtsiox-rswould not x-rccessarilyfollolv. An cxter~siax~ of die life spz~l-rtvould result in decreased adaptAility of the hr~lrtanpopllildtion because of increased colapctitior~for scarce resotl~-ces,such as fiocl, betvveen older people, who already would have repr-aduced, a l ~ dyounger people, t3erhaps yotrnger people could actapt ta tltis scenario by heconring more efficient in their caloric intake and metaholism duriilg tbcir reproductive years, But such adapeition t\7otrld bc difficult to achieve in a wctrld where people's lives were sigiifica~rtfylonger and tvhcrc colapetition for resources like food could be qrxitc fierce. Restrictions on procreatiol-r cotlld alleviate tile probletrt. Yet such a policy ~rtighthe zr~~fair to tlie yotrrIgl who would not have the saxne reproductive choices that the oid already fiave bad. It is at least intuitively pfausib(e that, in a t-irture overpnpulated worici with substaxltialJy extended buman lives, scarce resources could adversely affect the survival avrd reproductive pr-aspects of the yotrng. This cotrld ltarnr them by tltcvarting their interest in being healthy enough sc:, that they could sunrivc a11d prc:,crcatc.The bioof t l ~ e1ncchat:risr-r.ls logical a11d xnoral iniplications of gcnetic i~~anipulation of aging cdr111ot bc separated from those of ctvcrpopuladoir, g'rwen an extexlded h w 1 1 life span,
Accordi~tgto tbe pleic>trc>pi~-gcm hypothesis, which 1 ~ introduced s by Cgeorgc Waiams, ~ n o s gciies t ixivolvc bath biological beliefits and costs to hzrlnarl orgarlinns.T7'hs tipothesis is the faunddtioil of e\zlutiot.lary medicine, which ur.lderstnncls the body nxld its responses to pathoge~lsas a set of corxlpmmises that I~aveevnlved over tirne. In chapter I , I cited Nesse and Wllliams's claim that evolutioiiiary biolot;). is the t;,und.atioiii &?rall bioloLq9 and that biolo'q is the &?undation t;,r all medicine,l" O n this view9many genes have alleles that cause or predispose h u a n organisms to oiiie disease at the same time that tbcy protect them against a different disease. The 111ost 1\7ell-knotvl~texaiaplc of this is thc allelc &or the autosornal recessive discase sickle-cell ancr?lia. As already noted, oize copy of the Bckle-cell allele will protect agaillst xrtalaria, thollgh two copies of the altele will cause S(:.A.Tltis is an exatnple of a gene that has been selected to confer a surviwl dclvrlltnge on h r t ~ r t aorgnniurts ~~ in dxz, er1~7iro111~terlt with a life-direatening pathogen, specifically the X3Icllsttaodintrr pmtozoan that causes malaka. Another exanzple that seems to confirm the pleiotmpic-gem hyyothesis is the zcliatloiii bettvecn cystic fibrosis and typhoid fever. Stll+ing the rt-lation bettvceii SalmorlcfLj t y ~ ~ hthe i , bacterium that causes w h o i d fever, and the protein tbat, 1\7bcli illlterited in the &orm of W Ocopies of a mutallt alfele, muses C:E researchers hLjveshoxivn that S. t ~ huses i thc healthy version of the CFTR pmtein to enter the gut cells it infects,ff Notably, like the relation 17etl;sreerl SCA and nlalaria, the relaitiojtl between CF ancl S, typlri ir7tvs)1~*7es a trnde-off betweer1 a f~enericallycaused condidoiii and a coriidition catrsed by a pathogen. In each case, liiatural selection allows the expression of an allele associated with the more chroiiiic genedc concfitian becatzse it protects against the more acutely Itfetbreateni~lgpatbogcii prc-"domiiialztin a given c~ivimnmcnt.This yields a net rcprod~rctiveadvantage tc:, hurn,riz organisms by allowing them to reiaain healthy and survive in different e~zviroizmcntsuntil they rcxch repnxcSrrctive age. Strictly speaking, it is xrtislcading to label gexles as '"tlealthy" or ""nr.~healthy."WhiIemtltarlt alleles of genes can cause or n ~ a k e 11s suscepfible to disease by adversely affecting the proteins regulating cell functi.ons, the compromise between health m d disease in human organisms is at bottom a refiection of genes working to be translllitted into the next generation. Ncssc and Wi2liams claim that sencscerlce is the most tcling example of pleiatropy. l 2 Cgcncs that causally contribute tc3 aging and evcntudltly death later 111 life could bc seiiectcd for if they gave an advarltage to youth, when the force of rlaturnl seIectios~is strorlger. 'To the extent that
the plciotrcjpic-ge11e hypothesis reflects a biological bias tobvard the earlier part tof otxr lives ctver the later part, it is coirsistent with tbe explanaduring the tion of a g i w in terrl-rs of lxrlrtations accumdating in llrrma~~s post-repmductiw period Significmtly, the converse hypothesis mould be that genes ""slectecS" m confer ber~efitslater in life mtxld entail xnore costly mutations earlier in life. The manipuhtion of genes far bidogical benefits in later years could, over nlalry generations, result in a higher incidence of deleteknus mutations in earlier years. The ~rpshotof increasing langcvity fix ourselves in the prewirt generation could be a11 in06 acute early-onset diseases ancl. prem,rture death for creased il~cider~ce people in the distant future.This would bc due to tbe shift i11 the cotxrsc of natural selection through manipttlatios-r of the genetic n1echar3isrrrs of q i r ~ at g the gerrir-r line. Just becatrse the sce~lario1 llave sketched pcrtaitls to the relnote firturcr. does not dilllinish its moral importance, For, as Parfit ltas a r g ~ e dthe , moral significance of 8x1 event is not deternlined by its timing. The fact that an emnt agecting peaple occurs in the remote futrrre does not mean that it illatters less illorally, s-i~ic-c the claims of all peaple not to be harmed have equal moral 1\7cight, rcgardlcss of the Fact that they exist and make these claims dt different t i i ~ ~ eParfit s . ~ does say that "it rmy often be morally pennissihie to he less cuz-rccrr~edabout the more rernote eEects of our social policy But diis would never be ttecfirtsc these cEects are xxrare rclxrate. Z;t,zther, it vvorrld be becarrse diey are less likely to occur."" Presrtnlably; then, the mere possibiliv of an increase in the number of mutatio~rsin the hurryan gene. pool sltould not occasion nruch nroral concern. Vet it is not so fanciful ta imagine that mmy people would w n t to exd illeans ta d c ~so. And if the i~~echanisms of tend their lives if they h ~ the aplig 1\7crc genetically manipulated in ~nanypeople over mairy gcneratiolzs and altered t l ~ ecoarse of natural selection, tbcrl there could he a gradual ir-zcrcase in tlle x-ruxxrber of deleterious rl-rutatiox-rsdEecting htt~x~ans earlier it1 their lives. The pmspect of harm to jilture llzrrnans mould becornc irlcrcahgly probable over tinre. Tl.tis increahg probabilicl;, combined with the magritr~deof the Itarm tltat the nltrtations enrailed, provides grounds frx caref~lllythinking through the nroral implications of this type of genetic intervention. It is nlarally sigrificant that peaple lzugbt be harmed in tbc distrti~t f i ture 'by hLjvixigprcinaturcly diseased and abbrcviated lives. As Ncsse and Williams fbrther paint out, strc3ng iinmune dcfcnscs invctlving macrophLjgcs,Tlylnphocytes, and the suppressor ( ~ 5 3and ) necrosis (I'NF) proteins protect us kofrt itlfectior.1by v i d e n t trticrohes.15Hcfw-
ever, thc long-term coi.rsecyucncc of this protective iuni~lunerespoilse is lo~cv-Leveltissuc damage that can lead to chronic diseases latcr on, such xs arthritis, diabetes, and athercjsclemsis, This claim is supported by a recerlt strrdy concluditlg that athemsclemsis is an itlfiarx~n~atory disease that devel~ responses to viral, bacterial, or ops gradtrally tllmugbl C C ) ~ C ; I ^ I L I Cimn-tune e and 7: other p a t h o ~ n s , " " c t i ~ i o n of m o i ~ o ~ y t e - e rmacrophages lympltocytes as part of the immune response can cause inflammatory arterial lesions in infants and children, which can signal the start of the process and lymof atbcrogencsis, Sinilarly in rhertmatoid arthritis i~~acrophages phocytes predominate in the synovirxm, leading ta tbc ercjsiol~of' cartilage and bone, 1\7bich is tl-ren rcplaccd by 6brotzs tissue. A collstallt inNa1a111ator.). response designecf to protect the orgntlistrn earl): in life c m , over tinre; hecofrte an injztrious resporlse at ~nolecularand celltllar levels rnnnikstitlg it1 diseases of the body5 ttissires a d orgdrls. h addition, H~/icobilct~r pyji~ri, the bacteritlm tltat plays a role in producing duodenal ulcers, may play a role in some stomach cancers. Such coilclitions are examples of an association between cltronic &sease and infectious agents These sequclac Inay bc unavoicliablc conseqrzcnces of all inimui~esystexn desig~edto prcjtect hrzman orgdnisms h m i~lfcctioncxrly in life tta ensure and reproductive fitncss.This is xn expressiol~of the hypothtbcir s1~~wival g furlcticjn m d itnlxtt111e rcspollse are esis that genes m n t r ~ l , l i ~ lcell pleiotropic. If otlr bodies in general rind imlxnt~lesystezTts in parricular are a delicate set of trade-offs favc)rixlg the cadiier over the later stages of life, then it is possibje that tinkering at tlte gernl line cvitlt tlte genetic mecltanisnls of agiing to extend the human life span &3r people in the present and near future could make distant tilture people more vulnerable to infectious discases earlier in life. C3ne xnight claim that antibiotics and vacci~i~s c~tzldprevcilt tbls scenariclt fmia occurril~tg.But if thcrc 1\7cre more gcrletic i ~ ~ u ~ i t i oinn tbc s eels of hum12 organisnts, then it is likely that the celltzlar resporlse of the ixnrrtune systelxr anct its ability to x-retxtralize infectiotzs agents tvottld be weati-ened. Antibiotics and kraccines are designed to seimlrl;\te or stmnghten immune reqonse to invacjjng nUcrobes. If the tirncri.011 of marro~r-derived I3 ceUs and thymus-derived T (cytotoxic CD8 and helper CX24) cells has been canlpronlised by genetic nlutations, ltokvever, then one can question just ho?v effective tbcse incewe11do1.r~would be. For these cells are crucial in dcterr~Gningwhether x hui11a11 orpnisi-r.1will have adeqrlate i n i ~ ~ ~ u n o logical strength ta fend off disease-causing pdthogcns. The increased susceptihilir;\r to inkction ofindividerals whose imrntrne systerxls are itnpaired
from thc use of in~munos~~ppressive drtxg to reduce inNa~ai~~atior~ associwith HIV-AI1>S, are ated with autoin~munediseascs, as 1\7cU as i~~tdivicluals cases in point. Infectious agellct; elrolve so fast that our ixnrnwle c;ysterz?isare a l ~ ~ a ya sstep behind in respading to them. There is evidence of this iri the ixlcrcasix~gnuxxrber of antibiotic-rcsistd~~t strains of bacteria, srrch as methiciHin-resise~nt Sfc-rpflyhct~crnsJU~Y>I(S (MKSA) and v~ncon~ycin-xsistan t l:"lrrrrt~rtlcctds(VW). What X ltave desckbed would mark a perverse mist in the ctrrrellt disease prcjfile in xnodcril medicine, with early-onset acute infectious diseascs becomillg xnore prevalent than late-onset chronic diseases, and with peaplc gencraUy hL3\ai~ig i~lcrcasi~~tgly shorter livcs.There xnight c m ~be i a grad1x4 decrenment.~ We can imagine tbat Inany indivicluals would choose to extend thcir lives if the genetic tcchnolohy to do this bccaiae availat?le.Thosc undergc3ing the prcjccdure could have a prc>loi~gedperiod of vigor beibre tbc efC ~ ill and probably a moderate extension of life beyc3nd fects of S C ~ I ~ S C C I I sct a norrnal span of &out eighw-five years,They mi$t also be able to live nrhstnntialty b e p d this point. Idet us co~lsidereach of these scetzarios in turn. The n~otivadon&?rt l ~ cfirst scenario cvould not be ta ix-rcrease t l ~ cnunlber of lik years as such, but rather the number of years of vigor and thus the qu"Lir). of these yexs. Prt.sumablyI tkxs cvonld imply a corre~ponifing decrease in or colnprcssior~of the n u i ~ ~ b of c r years bettveen the onset of agc-related diseases and death," Id~dedUy,one would ~vantta delay tbc onset of &scasc until tbc completion of most or aU of ctnc's prcjjects ~vithina life plan. At this point, one still worild be plysicafly, cognitively, nncS etmotio11ally able ta enjoy one's achie'17ezrter1tf and die xzot too xrtuch later kern an acute illness sttch ns ptleuzrtonia, l"be rnotivatiotl for the second scenario wauld be the conviction that being alive is intrinsically goad anif herefore that living longer is intrit~sicallybetter than living f i r a shorter perlad. O n this view there is no point bepiid mrhich additional years of life ltave diilll~~tishi~~tg i~~argindl vdlue,This iniplicitly asstames tbat in being alive a person is free from tbc pail1 and suiFering occasirmccl. 1z-y disease and disabiji~ and has the capacity and o p g a r t u n i ~to undertake and completc prc~jects withit1 n masotla2nly long lik span. The value of a longer life tvill he cotldi-
tional upon the capacities of the perso11 ~vbosclife it is. In ordcr to dctcrthis, bc~wevcr,1vc need to rciteratittc the biological and pvchologic~l ser:lsesof""iife'h1zd die criteria of personal idex~tiqspelled out in Clzapter 1. The first sense of "life" is biologicnl and pertaills to the persistex~ceof a str~ictumllya i d t;lrnctiot:lallyintegrated httmdn orgailist:n.Tlze secorld sense of4'Iil'e"is psycil"lof;rcal and pertaiils to the capacit-y for mental life and the connectedness and condnuity betmreen mental states over time. ['ersons are consdtuted by their organisnls but are not identical tr:, tltem, since they are esserldally defi~zcdin terms of psychological rather than biological propertics.a_lthough the life span of a persoil overlaps the life spa11of a11 0rgailis17~ ta a certain extent, tbc two crltitics arc not coextensive. Humar~orgdnisri~s have lorlger life spans than persons, begirlnitzg eartier and ending iater than persons. So hllmarl organisms a i d persoils are ontologically distirlct kinds. Psychological corlnectedness and corltinuiq form the criteria of persoilal identity The first relation consists in the holding of particrllar direct links bet~veenmental states, These connections can be stt-anger, holding over shorter periods of time, or weaker, holding over longer periods. The seco i ~ drclatic:,i~is the ancestral rclation of psycfiological connectcdncss, consisti~~tg of t3vcr-lappiiig chains of strong connected~zessand extending tlvcr lorlgcr pcrirrds of d n ~ et h ~ nwhat is i~ivcrlvedin partictzlar direct links bet-wecxz rl~cl~tal states, Uxtlike coi~x~ected~~ess, condntiit)r does not: dcllxrit of degrees and is a transitive relation. StrictIy speclkirzg, personal identiq is based on the relation of corltinuit)r rather tltan connectedness. Variit maintains that connectedness pertains ta "wltat matters" but is not equivalent to identity,zyYct, in an intuitive sense, what matters to us and our concepdon of onrselxs as the same indkiduals persistliig tlirtjugh time cannot be separated. Accordingly 1 w i l use tbe ilIorc il~ttuitivcsense of identiy interchangcxbly with w h ~ matters t to us and base batb on tbc rclatioi~of conncctcdness. Specifificdlly, 1 1 \ 7 d be concerned wit11 coi~nected~~ess betweex1 forward-loc->kiq desires ancS irztexltions and backcvarcl-loc.>kitzgrl~en-~ories, uniiied kom the standpoint of the conscious prcsexlt, The ontalo@cal disdnction betmreen human organisnls and persoils is crucial. For mrhen cve reflect on the desirability of a longer Life, it is the continued conscious Life of a persoil that we have in nuncl, not tlte mere coi~ti~iued biological functioning of a b u i ~ ~ aorganisin. n Few, if any would 6i1d coilgc~~ial thc thought of a11 exterided life spa11 consisti~~tg in a persistent vcgc~itivcstate, with our orgdnisil~ssus~ii~icd irzdefi~~titcly by mcchanical l i k nipport. Although the contixltled tiirlcrionitzg of solne parrs of the
body and solnc r c g i o ~ ~ofs the braill arc necessary col~ditionsof an cxtcnded biological life span, tbcse regions arc not sufficient &for tbc contilizied camcious lik of a person. Not A parts of the brain can generate arid s~rstaititrtet:iral life. It1 additioli, tlie qtlalitativt- aspects of 11:tentalstates, sttcli as corisciotxsncss, aricl the contents of these states are not solely ftzrictiaxis of the body and brain but also of t l ~ esocial and pb_ysical e~ivir-anmentsin which we exist. Nor can the body and, brain alone fully explain how we integrate, or give narrative nleanttlg to, our past- and futrxre-oriented nlentcil states frc3m the co~zsciousprcwnt.Tbe contiliuccl. col~sciouslifc of a person is & nccessary condition of the rationdl desirc for & longer life and of rational concern about onc's future self. Intuitively the hest psyclsologicsl life, the one wit11 the highest level of quality o r weli--l-tei~ig,wili he one in which a person mnrisleritly has acl~ieverne~it-s for a good number of years, atid where the level of these achievements &clines just before dratb. As noted in chapter 2, most people have asynln~etricalten~poralattitucies, being more concerned about the future than &out the past, We care more about the good experiences we r ~ i g h ht ~ v ein the futurc than about those we h ~ v cbad in tbc past, prcfcrring the good ta bc ili tbc futurc and the bad to bc in the past. CZve~ithese asy~nl~~etricaf attittides to\vard tbc past and futurc, tbc ideal contour of 2 life w d d 11me the hulk of bad experie~lcesin the early stage, zrtost of o ~ l r achie%7emet:itsiti the middle to later stages, and few, if any, held experiences associated with the pain and silf-Teringof disease i n the last, lropetillly short, stage, If increased longevity entailed condnucd pl~ysical,cognitive, and emotio~ialvigor and a re~ardjngof senescence for a considerable period of l d more opportunities for achievetime, then more lik years w o ~ ~ offer rnerit, as 1\7cl as 0ppo3rtunitics to c~ijoytbc fruits of these achievcmcizts tbrough rcficctivc memory Such a life 1\7cnuld have a very high level of value. O n the other band, the colitour we want to avoid is onc of an extexided life span coiitaining a disproporrionately long last stage of disease atid tlisabiliq It1 this case, a life with a prolollgcd final period of tnort3idity wotxld zrtake for a wretched last stage and might even give that life as a whale a net disv;~ltle.This'uroulci be the case if, as a functio~iof our temporal bias tokvard the &&Ire, we care more about avoiding bad experiences in the last stage of life t11ltan in ally other stage. 1"c.rhatf~thebest ilfustration of the stcitc of ;tff;itirsjust described arc the %awls,"lo lives of Jonathar~Swift's Strtxldbrug, the inimortats ilz C;~rllizl/;r!c These ixiclividttals have clidless lives diat are vvortf-slessarid ir-ztolerable,owing to tlie t;act tliat rnore life years for thegm entail physical, cogllitive, and
affe~tivcdctcrioratioi~,precisely the sctrt of xnisforttlne tbat a11 extended hurn,rn life spar1 should avoid.Yet, eve11 if gcnctic manipulation of the ~ztectnanisn-1sof agi13t-fcould ellsure a life considembiy longer tl~anthe present 1mrt7il with one's capacities intact, the wlrre of sltcli a life c o d dirnirlish beyond a certaitl point far the peopje who would five it. For most of US,life plans, and prgects undertaken within these plans, are nlacle with the understanding that there is only so mucl? that we can accomplish in lifeeThereis a limit to the ilrrmber of prgects that call sust;ziti our i~itcrcstin persistilzg as perxxx i ~ i t othe future, as 1\7cU as to maintain tbc saim level of interest x11d enjc3ynIent in experienci~lgprc~jectsindefii cogriitive rcsourccs of kri0\\7ledge and nitely This is dac to tbc limit i ~ our imqinatiotl. Moreover, this rnny explain both our temporal bias towarcl the tteizr (as distinct frorn die tili.qtaftf) ftxtrtre ancS orrr itlea of what: the corltour of a life should be. O n diis view, even if the cxterlsioi~of our lives inr e not entail the same infirm Fate as Swift's definitely into the f ~ ~ t u did Struftlbrugs, it is dotlbtful that we could continuously geilerate a series of pi-ojects that cotrld sustaiti our desire to go on living." Bcyctnd x certain pailit, coi~tinucdlife wcjuld bc at best value-nerttral, at wtjrst i~italeralzle, but xnost likely undcsirablc. In Thornas Htlrkd's 1\7ords, ""lke x play a life can have a deiioucmerit, but it should not take up WC>-thirdsof its r u r ~ i ~ i ~ i g tir~le."~~ One xx~ightobject that, with a loxlger life span, we could devise digerexlt plans and projects that would have expan"cled tenlpomi horizotls.We could $an fbr a sequence of prujects that .vvotrld be internally 1-elated,each of which could constitute a lifetime project given our present maximum life span.33 But our brains have evolvecl. in such a way as to maintain eqtxilibrium bcttvcen anticipation of the fittare ancl. mclaory of the past. Too 111uch xnclnory xnight co~aprc>rniseour ability to conceive of and undcrtcike n c prc$ccts, ~ which depends on our alzility to x~~dcipdte the filturc.. tr~sofaras there are limits to what we can atlrjcipatc in the i'iitrrre arld re~zternberfrarrz the past, we could sust.dirl our interest in any ~7rojectfor onfy a lirrtitcd period of tlnle, fJecatrse of these cogx~itivelimits, and becatzse orxr &?imrard-loohng &sires and backwai-d-loohng memories \votilci be only weakly connected over long periods of time, pm~ectsundertaken at much earlier and much later pe"iocts of life would be at most mreakly connected for us, This shctuld lead us to qctcstion just ho\v intcr~~dlly relatecl. these prc3jects could be. Lxter in this section, I 1vill G ~ C Cempirical rcsearch on illemory to support tbis point,
I 60
Genes and Future PcopIe
In considering the possibility of a substantially extended life span, we need to ask how this would affect psychological connectedness between earlier and later mental states.Would a significantly long span of time between earlier and later mental states weaken the relations between them and make then1 so different that they effectively belonged to two distinct persons? O r would the relations between these states be strong enough to withstand the test of time and ensure that they were of one and the same person? When we say that we want to persist as persons into the future, it is not just qualitative sindarity between present and future psychological states that we have in mind, but numerical identity.That is, the person who will exist in the future must be the very same individual who exists now. I11 anticipating or planning for my future, it is not enough that my present psychological states are similar to other psychological states at a later time. I assume that these states will be mine and that it will be me who exists at that time.Yet, I want such states as my earlier intentions and the acts in which the intentions are realrzed to be united by the stronger relation of connectedness, not the weaker relation of continuity Parfit acknowledges that "connectedness matters more than continuity in theory and practice."34 Psychological connectedness is necessary for what matters to us. Continuity does not admit of degrees and is transitive. Connectedness does admit of degrees, however, and over long periods of time diminishes and fails to meet the condition of transitivity necessary for personal identity in the strict sense. If connectedness is a necessary ground of what matters to us in the hture, and if connectedness diminishes over time, then in an extended life span it seems that we may have to settle for qualitative similarity rather than strict numerical identity as that ground. Furthermore, assuming that there is congruence between prudential concern about the future and the intuitive conception of personal identity through time, and that the psychological connections definitive of personal identity dinlinish over time, it foblows that the reach of our prudential concern can extend only so far into the future. Because any mental states in the distant future would be so weakly connected to any present mental states, a substantial extension of one's biological and psychological lives would not be desirable from one's present point of view. In such a scenario, the identity of one and the same structurally and functionally integrated human organism most likely would be preserved. Its biological properties would be relevantly sindar between earlier and later times. But it is unlikely that the identity of one and the same person would be preserved, owing to diminished psychological connectedness over a long
perirrd. This is according to the i ~ ~ t t ~ l t conception ive of personal idcriti@)l. tbat I have adc~ptcd.Yct,eve11 if one adoptccl. a strict coi~ccptionof personal ideiltiq based on psychological contirluiy, there would not he any reason for an eadier sclf to care about a T I I U C ~later self, sincc the conxzectioils necessary to grc>uililt v h t lxlatters to US tvould have gready dirrlinished. There would be a ditiergence of our h i d o L efrom orrr psycltoloCq.But it is our p s y c h o l o ~tltltat proviks rational gro~rrrdsibr concern about the hture. The idea that: otrr biological organisms might exist for up to 200 years, w h l c the psychological relations in xvbich personal icleritity through time co~~sists bccarne discctnnectcd and disco~~tinuttus well before this pai~lt,would not be very comforting. A for~genough biological life wcjuld entail distinct psychological lives of distinct persons, T r y i ~ ~tog extend lxly p';ychoiogical life as a person thrc~ugllge~leticmanipulation of the ~xlecha11islns of aging has the paradoxical coilsequence that, as my biological orgdnism continued to exist indefirutely, I cvonld cease to exist and a person distjnct- &m me would begin to exist h e p n d a ccrtait~point. My eadier and later selves egectiwty w u l d , be the selves of digcrcnt persons. We i ~ i g h calf t this Mctbtrselah's lf"aadrlc, after the biblical g~wrc. Ad~xittcdly, tbc case of Metht-lselah is ail exaggcratcd illustratic>i~of the problem of rctciining or fosi~zgperso~lalicleritity over an exterided period of time. Rut X3avid Letvis e~xlpfoysit i11structively to shotv llow the relations betkvecxz earlier and later xnental states can b e c o r ~ ~discoil~~ected e a~lcS~ ~ S C O J Z tintlous firr a person who lives too long: Constder Mtrlzuselah. At tlre age of I00 he. still retiiernbers h ~ cfirldhood. s 13ut new rrreniorres crowd out the c~ld.Atthe. age of 150 he. h a ts-tdrilly any nitmorics yertr.At tlie ~ g of e 200 he lids hardIy A I I ~)in?eilit l i ~go t back tnefore hls t\ive~-ttieth ories tfut go back tnefi'ore his severltietli year, and \o on.When he dies at the age of 969, he ha%har&y m y mei~ioriesbeyond his 839th yertr.As lie g r ~ wolder \ lie gru\\r\;vrwlser: Exis callow olsinionr 2nd ch~rdcterat age 9(J have v,inrshed almost willrout a trace tty age 220, ttut t~issprtlial~sand cfi~racterat age 22U have mnrshed &nos&without 2 trace" tty age 350. He soon learns that re is futile to sec goals for h1111self too far ahead. . . .For Methuselah the. Gdxng out of persoml xdentxty loolrls large. as a fact of hfe. It is incu~~ibent on us to ~ ~ i a xkt chterafilly trtle that he will be a d~f:f?recctperran aGer one and c~ne-half centuries or so.
T h s example sho\vs how sclf-intcrcsted colzcern about thc hturc is illtinlately relatecl. to thc idea of persisti~lgthrough time as the same person, The less psychological connectedness between the mental states of tny
present self and tbosc o f a remote future self, the less rational it 1vill bc &or 111e ta be conceriied alzout thdt future self, ~vbicharhwably would not bc xxtine. Parfit offers mmc support iirr this point by s+ng tliat 'konnectedness is one of the tkvo rejations that give me rtldsons to be spcciafly concerned aborrt xxry own f~iturc,.Xt can be ratioxlal to care less when one of the gronncis &?r caring cvd hold to a lesser d e g ~ e . " . He ~ ~ ~further clain~s that w e can "treat trreakly connected parts of one lik as, in some respects, or to some degree, like digerent lives."37 Suppose that I k o r i ~a ~desire and i~itentic>i~ to tlndertake a cerr~til~t project arid to complete it by a certain time in the filtt~re.WhenI do this in the present, I assulnc thdt tbc prc~jectI value now 1vill be sctmctbing that I still will d u e when X cornplete it. Moreover, I nssrrtrte diat, when I colnplete it, X tvill be able to rerrlexxrber rny earlier desire and intexltioxl. For xxly coilcer1-1 about corxrpleting the project to he raiollal, there must he a w l i v or illtegration of tlte mental states of the desire and intention at tlte earlier time" and tlte mental state of ren~emberingmy earlier desire a l ~ dix-rtention at the later time. What unifies these ear-lter and later mental states is my coi~sciotasa\\7arcliess of niyself as a being 1 ~ b persists o through tinie as oiic arid the salnc ixidivicludl, Rut if thc connection bctwecri 1n-y earlier desire arid later rIIeiaory weakclis as tbc leiigtb of time bctwcen thcse r~~erital states increases, to tlie point wilere I n o longer identify with the desirc, or its coiltent, then it seenm to hllow tlidt nt)" c o x e r n about tlie proJect, and the rational basis for it, can cxter~clonly so far into the ftztrtre, t l w i l ~ gto ns nle~ltal tlte p a s s ~ eof time and its effC;:cts on the c o ~ ~ i ~ e c t i obettveen states, there w o d d not be enough psychological tinity of eadier and later mental states ibr me to rationally care about a self and its pi-ajects in the distant future. Onc could justify this by cxplainilig that tbc ~nclitalstates of tbc futurc self \vt>uld be the mental statcs of a differclit person. It is truc thdt if OIIC: is conti~~tu~>usly i n v ~ l v ~ind a very long-term project, then or.lct9sa'i.vdrer:lessof the project 2nd its continuous status w d d have t&e co~ltinuouslyupdated. 14owever, upclar-ing tlie project nt different stages worrld not giclrnrlte~that axle's xxret.lral states at the earliest and latest stages would be snfficiently related to sustail1 it over a very l o i ~ gperiod of time. The farther apart in time one's attitudes are, tlte weaker the connections b e ~ e e nthem will be, which could undermit~ethe unity a l ~ d c011tixiuit)r of the prc$ect, as well as one's illterest in it. T h s poi~itcan be s-tzppartccl.by a biological explanation of hmv certain gencs and strrrcttlrcs of the brain control memory C:oi~sistciit wttb an evelutionary explnrlation of huntan biologx, zxlegnory is designed in stldl n
way as to cribaxzcc thc survival capticicy of bumaiz organisins so that they can reach reproductive age and trailsinit tbcir gencs ta the next gencration. As an essential part of a btrlrtan orgi~nisrn,the hrdin wdf n ~ aZlo1v t the ~xtindto become Ctlttered with memi>riesthat serve xzo ptirpose, especiaiIy if this interferes tvitll other rllelital functiox~s.Even if braill cells so~rtel~o\v could be re~trvenatedthmtrgh genetic nlanip~~lation in the same way as cells in other parts of the body haw the brain and mind firm, store, and retrieve nlenzories is deteralined ultinzately by what evellts the brain deems useful for tbe organisin as a whole. Short-term mclnory is essei~dal ta our synchronic sensc ofidentiw to our conscious awareness of crursclves e,urtstilzg at a given tinic. Long-term memory is essential ta our diachronic sense of identity to ottr conscious awareness of ottrselves persistitlg thmtrgh time. The latter is eqecially gennal;Ic to the congrtlexzce bemeen p e r s o d identiq and prrttlerztial concerll about our i'iitrrre selves. Menlories the brain deems txsefiil are archbed via the hippocampus to a long-term storage site in the neocortex, the most recently evolved part of the brain. The action of a particular molecule-cyclic AMP response elei w n t binary prc3tein ((I:KEB)-m,rintain a11 opti~nalbalai~ccbcttvcen l e a r ~ ~ and i ~ ~Ec3rgetrii~tg g by iaodulati~lgthe fc~c)riaatfon-st~rage-retrieval ~>rc>ccss.~TRER is a transport: factor responsible b r switching 0x1 particular f~er:lesthat ~xrarzvfacttrreprc,teitzs necessary b r long-terrn Ixretmor-Jrfor1xtatiot.1.C:rucialfya(_:REISc o r ~ ~ eins two types: "activalor"' rus to care adbo~ittbesc distant future selves. If I decided to hLj\acthe cells of my body and brain genetically r~~anipulatccl. so tbat I could have a much lorlgcr life, tbcrl tbc biological organism that existed in the fiztrirt. lxlight be identical to the one of tvhicb 1 arn p ~ s e n t l yconstittreed. Mrrt the person existing at tlie ellcl of this prncess I Z I O S ~likely w trlcf not be rne becaltse the requisite connections bemeen past and future nlental states for retattling identity kvould have mreakened so M I U C ~that they na longer wotrld hold.The paradox here is that the nlot i ~ n o nf i r the gei~eticmanipulation kwtllci be to erctea~dmy psychologii end, xvbat I achievecl. wt:,uld be oi~lyan excal life as a person.Yct, i ~ tbc tc~lsio~l of thc biological life (of 211 or~;~anisin tl-idt at most wctuld be oilly weakly relatecl. to me, Extending the hu111an life span substantially beyond the present 11orr31 w t d d be tl~lilesir~ble because the penon who underwent the ge~lctticpmcedure for all prncticai pttrposes would have gone out of existence bebre his biological orgi1:anism did. Alchczugh otrr ~ztentallife catlsally depends on t11e contJllt~edtirncri.oning of our biological life, it is the former that generates and sustaitls our desire to live l o ~ ~ g e r , The collseqrreilce I just described cvonld not occur if the illcrease in longc\ait)r were moderate and did not extend too Far bc)8oi1d tbc lin~itof a normal biological lifc span. For, in tbat case, tbc tc~nparaldistance betw~cen present and future ~nerltalstates would not bc so great as tc:, severely weakexl the connections holdiz~gbetkvecn them The relations x-recessary to retain personal ides.ltir;\; stil would hold, asslrlrling tlie continued rlorrnal f~ix~ctionitlg of the body ancS die reje'17ant regioxzs of the brain, as we11 as the genetic a l ~ dbiochenlical col~ti-olson nlenlory and otl~ernlental states. A ,rrod~iafcextei~siourof the human lik span could preserve the integrity of our mental life while sustaining biological vigor, The prohlem with trying ta in~morrztlizecells and thereby bring alzout a subsfntlfinl extcrlsiorl of the life spa11 is that thc biological gaili would entail a psychological loss, the loss of pcrsollal identity and the rnerital cc>nnections that ground x\7bdt lztatters to 11s. Such a ifi: wotlld not be desirable fctr any person? arlci there-
&ore there wc3uld not bc any prudcrldal reasoils &>rsulzstrtntially extesiding our lives.
Conclusion If one's biological life kvere to be extended substantially into the future through genetic manipnlatioi~of ES cells, telomeres, or other nlechanisms of aging, then one would kw~nta corresponciing extension of one's psychalogical life thdt ensured that onc ~vcnuldpersist as one and thc saim person thrcjugh tin~e,I have argued that, although thc dcsirccl. congrucrlcc between our bic3logical and psychological lives could be ensured if tbc life span were cxterzclecl r~loclerntelyinto the f~ittrre,a substaiztial increase in loizgeviv would severely weaken psychological connected~lessover a vast temporal period. It would corne nt the expense of persond identiq and rational grotrnnf fbr coilcern about the tirturt.. Making the body's ceUs and tissues less susceptil4e to age-related diiseases n1ay result in longer and nlare vigorous lives fbr otir organisms. But it does &?llowfronr this that the connections bcttvccr~our earlier and later xnerltal states would be strong enough to ensure that thc same person who t~ndenventthe genetic 1116nigulation wt3uld still exist at the csid of the pr~~cess. A substiintialfy longcr life wotrld not be bad far n person (inn sense, it ctjrrld r.tnt be, if that person ceased to exist while his orgdnisn-I coiztinued to exist); but it wotrld not be desirable either. Tlzerebre, there are no good pntdet.ztial reasons b r srrbstailtially exteilding the human life span. Flrrthermo~,even if our biological and psychological lives could converge in a desivalsle moderately extended life span. we .\jvcjr_rldnot sinlply want to retard senescence and the agc-relatecl. discdses it entails.We would w a i ~ ttc) C O I I I ~ ~ C S Sthe period bettvcen the onset of these diseases and of cells, tisst~cs,and orgdns death. A life in w h c h the vigorc>usfu~lctioi~ing was extencled beyoild die present rough lirxrit vvotrld not be desirable if it were folloxved by n pmlonged period of nrorbicliy before death, Aittlough one cotrld lxrake a case far extelzdil-lgollr itzdividt~albiological and psychological lives moderately into the future, coilsideratim of the collective consequences of doing so provides reasons for rgecting it, A wodd in which everpne's life span were extended, b e p n d eighty-five years could increase compedtioi~&or scarcc rcsourccs and lo~cverthe quality of life for aU.Tbesc collective ekFects in turn could 111ake it worse for each person to havc a loi~gerlife. It also could inipase an unfiair burderl on the young, who would have to pity a considernbie arnotrizt in payroll taxes a i d
r ~ ~ a kother c sacrifices to support the i ~ a n w o k i i ~old, g xvhose nuinbers could exterid over several generations. InsoFar as increasi~lglongcvit)r could he corlsidercd as a fol-rn of genetic ez~l~ancen:rezzt, a d insofar ns dle procedure w o d d he costly it would be rnore morally pl-rferahle to use resotrrces to itnprove the lives of the large numher of existing people whose quality of life Calls below the critical level of a decent n ~ i ~ I I n ~ u n ~ ,would T h i s nlean diverting resources f m n ~genedc tecltr101o~qtr:, pi-ogranls aimed at inlprovirlg the health of poor, diseaseci people. Tlte need-based claims of the worse off ta have reasctnablbly long lives have Inore moral weight than the prefcrciicc-based clainis of the better off tc:, have loilgcr livcs. In tcrrns of c~ac>lutioi.rary b i o l ~ h ythe ~ trade-off eri~iiled'by piiciotrc3pic genes suggests that genetic mnniprzlatiorl of cells at the germ line to extend the nunll-ter of tirxres they divide runs the risk of increasing the r~rt~x~her of deleteriotrs genetic mutations in the btzxxtar~pqulatior~.Altering gegles to make us in the present generation less susceptible to chmnic diseases later re more susceptible to acute cjjseases earlier in life could make f u t ~ ~ people in life.There could be a gradual increase in tlte incidei~ceof infectiaus diseases in youilger people, x%7hichcould result ill a radical change in the crznre of 1nortalifi)l.and lift expectailcy over Inally generatirri~s.It could even 1nea11 that a sig~ificantnurnbcr of peaple in distant filture geiierations might not reach repmdtlctive age, whicl would diminish the nun- her of people who would exist. The nlain issue here is a rnor;lI one. If the profile of disease were to shift as 1 have suggested, then people in the distant 61ture 'vlrould be harmed by the dekat of their intexst iii having a reasonably long and disease-free lik. This harm would be the eRect of nrlr pi-esent genetic manipuladon of the r~~echanisms of aging ta cxteild our ~ ~ ~ lives. 7 1 1The Fact that they do not presentty cxist but wlll cxist in tbc distant filture dttcs not dir~ir~tish the r ~ ~ o r kxce al of their claim not to bc harmed. A inere difference irz time does riot rxlatter xx~orally Utirnately, it is this risk of lzarm to futrtrti, people?in additior:~to the ttrldesirable consequulces for personal identity and prtrdeotiai corlcern about our h t u r e selves, that provide reas~nsagainst geneticaUy manipulating the mechanisms of aging to substannally extend the human life span. Accodingly, cve cvould do well to xlinyuislt our generocentrisn and egc:,centrisnl a i d come to realize and accept the biological and psychological limits of our orgailislns and our selves. We should live by the wisdom of llssallx %C): 12 and ~nakcthc days we have in our actual liniitecl. lives cc>u11t.4~~
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1. Tbcse and other related iss~xesarc discussed in Mark Rothstcitz, cd., C k nctic S c i ~ t sI)rc:rt~actir?q : l3rit)acy sad C:(J~fideflt~aljf)I irz tlw C;rstrrrzs(Oxford:CXat-c.ndonPress, 1984),esl~eciaflypart 4; Heyd, C;erzf.tlric,c: iZ/ltlral LSSZIC~S ilt Crenfi(~f? qf Peopl~(Berkeley: Ur~iwrsityof California Press, 19922). 4. ICitcficr, 'lhc Liws to C ( J ~ IT??c ~ P A: Y c ~C;PIIC#~C,C ~l nnd Hlrr~rual)c>.usl'bilifl'rs (New h r k : Sir~ronCi;r Schuster, 19962);MeMahalz, 'i%c Etlfics r?f'Killit.tq(Oxford: Oxford Universiv l%rrs, 200 1), 5,JVhy t;tPe C 2 t Sick: The X c t u S~icnce(lf Il~noi~ziun ,li/Iedicislc-.(Netv York: T i r ~ ~ e s Books, 1994). 6, Frorrl C;/TQ~~CL" fi? C;/IO~CV: C:e~~c.tr'c,c iirrzdJz~sticc.(NewYork: Canzbridge Urrivercity Press, 2000). 7. Elltics cztzrJ flw Lir~ifsof I)hil~~sopdzy (Carrtbridge, MA: Harvard University Vs-CSS, 1%5), 6.Tbc Latin ttrnr is rnc~mlitas;the Greck ters-xl is pt/~or. 8. S)ve~;iytlWrtt4e:?'he 'i"ttec~rt, nrld IJractiie r?fEqtzt~lity(earnbridge, M:Harvard tinivcrsiq Press, 2(fOQJ), 485, n. 1. 9, Sec, for erra~~~ple, f". M, Karl~rn,""Non-C:os-r~equcntia1isr~1, the 13erst>nas an End-in-Itself, ar-rd the S i ~ ~ i f i c a n cofe Status,"' Philosoj3hy G Pt-lltlic~4lf22irs21 (Faff 1992): 354-389. ~
C
I
Chapter 1 1. Sec Victor McICusick, l%ft3fldcliatlltzhcrifiaice irz ,44izrc: C6italr:qzie rrfrfAutrjranrul Do~nitzatzt,Autrjranrul fi?eii~ssi2/1; atzd X-Linked l3/1cnc~rypc"~, Tenth Editio~z(Balti-
n2ore:Johxzs Hopkins University X3rcss, 1992). Introductioxzs to genetics rnos-e pertitzcrzt tc) the philosophical issues I address ixzclude David Suzuki and Peter 2 %Clnsl? ~ Ucltzd~c*enthe AYctrj C;erletics nnd Hrirnnn E/nltic~s ICnt_tdtsoxi,C:en~tl~ics: (C:aiiibridge, MA: E-Iarvard Universi~Press, 1YC30); Darriel Kevles and Lemy E-Iood, cds., T'lzt. ns+f;Ir Heirltl? arld Social I41lir)j (W~shirrgtoxz,DC.: National Acadcr-xly PI-ess,19tb4).Maxwefl Mef-tifniariarzdJeErey Botkin oB2r a cor~ciseovcrvicw of the scientific, cthicaf, and policy aspects of thc Gexion~cProject in Access fct tltc Gcllzonte (Washington, L>C:: C;corgetotvn University Press, 1998), chap. 2. A rl-xore coll-xprehesrsiw discrzssion of the Vrctjece is given by fJuchanan et al., Front Cb~anccrt) Cl~oiccr: Cit7tzetlu alzd Jzistice. 5, Fronz Xk, Lipkitl, ' T h e Cftlest to Break the Huxnan Genetic Code,'Yt?~ ( ~ I I Decenzber--_jantrary I, 1991.: 46-48. Cited ixr Melzlnzan and Iliotkitl, 2 4. 6, "Medical and SocietaX Conseqt~ex;icesof the. Hunzan Ger~ox-neProject,'" LVcw En*qlalzdJc~nninlrtf' l%f(>dicit.tcl 341 ( 19tbY): 28-37. Also, Fraxzcis Cc~llinsarid Victor McIns,1W91); and Marc Lappe, The Tizo qf fttlllzurtolqqy (NewYork: Vlentxizr Press, 1997). 13, X3ro13ollents of this view ixrcXude Christoplzer Boorse, "Wr5afth' as a Theoreticaf Concept:Y/tilt)soj~dzyoj" Srir.fzcc. 44 (1 977): 542-571, and Leor-2 Kass, ""T11e Ex-rd of Medicirze and the Pursuit of I"Xealtf1,'"ixr Bu~tard .tr"z ,%re 4V(ztz.tml Scicrlce: rt.fr'af~;qysad Hrdltlnn /afnirs ((Ncw York: Fr-cc Press, 1985): 157-186, A n ~ u c hbrc3adcr (too broad, X believe) defi~zitionof4%health"i s givcrz in the preai-xlblc to the Cozzstit~rtioszof tf-rcWodd Hcalth Orgazzization (1%64;C;'"""Hcalth' is a state of coizrpfete physical, nrcneal, and social well-being ar-rd r-rot rl~erely tile absence of disease or iilfir~~-ilv.~' 14. ""The C;enolne 12roject,Individual L>iEferer-rces,and Just I-3ealt11 Care;" in ?1 Murgshy and M. Lappe, eds,,_fttsticecznd IJW I-Xidrltatz Ger~ttrllc.I""rcly'crr~(Berkeley: Universi-~yof (3atifc)rnia Press, 1994): 1 10-1 32, at 122. Daniels first formtzXated Ctzw (New York: Cambridge tilliversity this drrhitioxr of health ixrJ~stH~>tglrl.r PI-css, 1985). 1.5, Jai-xlcs Sabin arzd Norlnaxz Dazzicls, "Deternrining medical Nccessit-).5xn Mcxztal Hcaltl-r 13rracticc," Hastirtqs CPM~C~F fi?e~~c~rt 24 (1W44):5-13, at 10, 16, Preben MO Mortenser-r et: al., "Efi>cts of^Falllily I-3istory ar-rd Place ar-rd Seasor-r of Mirth on thc IXisk of Schizophrenia," &YewEt?qlafzdJl)trr~jnlqf iWedicitw 340 (February 25,1999): 6113-6(>8, and Nar-rcy Andreasen, "Understanding the C;ttises of Schizoplnreni;1,'7I(lid.:645-647, 17. Boorse, "anthe Distirzction Between Disease alld 1llness:"irz M, Cohen et al., eds., r"t4crrlil-is;te.tr"ztzrJrr/2orul I)/tr'loropdly (Prirtceton, N': Prirzcctor-r University PI-css, l%$): 3-22. Also, Eric (IZassell, 'ikLVatirrc * .c.rtf'S~!feht;qarld tlzc C;"c~uls.c.$ ,'lfefi.nicit.te(New b r k : Oxford Uni.c~crsieyPI-css, I W I ) ,
18. Kitchcr discusses tbcsc two t-xlodelsof diseasc in 'flw Lives to C O ~ chap. ~IP, 9, '""nclinliting Dircasc.'" 19. Ibid., 21 h. Enzphasis added. the Ccne ,Wj~t)l,85. 20, Hrxbbard ar-rdwald,IixpEodi~~~q 21, Natio~ralnotu, 202. 28. Ibid., 21 2 .' Also, !>avid Lewis, ""Survival and I d e n t i ~ , ' " ~A,~ C>. Rorty, ed,, 2 7 lliezztiticls ~ qf I>t>i.?;or?r (Derketey: Ul~iverrityof Cafifc>rnia Press, 197('>): 17-40, arzd Peter Unger, ld~tztitj$C o ~ z s c l t ~ t s zarid s Kzlr-te (New York: Oxford Urrivcrsiq Press, 1990). In 'f %c.View-Fl~nrL Y o ~ ~(Ncw f l ~York: ~ Oxford Uxzivcnrs i t y PI-css, 1985), Nagef dcfirics pcrsorzaf identity ixz tcrt-xls of psychological continuity; ti~o~z& he traces this uftir~iaee[tyto the brain alone, "Where the brain goes, I go" (41). l2arfit a~rdLewir a~uintainthat psychological cor-rr-rectedness ar-rd cor-rtinui~ycan occrzr in brar-rching Gtr111s ar-rd appeal to split-brain ta suysport their positior~.?'l-lisulldrrrlies their and ather thought-experix~ze~~ts claix~zthat identity as cuch does not r-xratter,tinger and NageX lzold that continuity does not dtow for branchitlg but reqtlires a tingle tlnity of consciotusrress persisdtzg throltgh ti~nc,X will asstfnIc that psycholr)gicaX coxz~zcctedncssand corztixzuifiy arc ~zor~brarrcfiixzg. Furtlher~norc,I -will assut-xlc that the partic-ular
brain and body an individual has are esscxztial for idc~itiq;not just alz): brain or body will do, 29. I'rrol-xlincr~tcoxztexnporaty n~ateriafistsinclude David Arxnstrc)xzg, A ,'lfat~vialisf711~0ryof iWifld (C:aliibridge: C:aiirbridge University Press, 1969);l%~xl MA: MIT Press, 1984); arrd tlrr'cs2 (2988): 227 K X follow Buckle it1 cXain~ixrgthat zygotes, embryos, ancl early-stage fetuses only have the potentiaX to pmduce persons, -which docs not imply thc logical relatloxz of idctitiq holdirzg bctwccrz thcse diEcrc~ztstages of hut-xlarr dcvcllol-tn~crzt, as inlplicd by thc pote~ztiaftc) become persons. 33. A si~-xiilarpo"tio~r is defended by Ly~irr$~SO)MS tirld Bodr'e:A C2onsritrrriori T ~ P I Y (New llork: C:aiirbridge University 12ress,2C100). A sustailred del;errse of the view tl-iat we are esserrtial1y r,rganis~irsis give11 by Eric Olson irrl 'rlze H$.rniar?AtzitttaI: 13t7fi0t?al Jd~jtfitytVifhotat IJsycholt?yjr (Oxhrd: Clarendon X3rer;s, 1997).PeterMin In~vagenargrres irr the cax-ne vein ixr rr/2nterial R~ift,ys(Ithaca, NV: Cornell University Press, 1990). 34. David Wiggitzs, Safl~cncssarld S~hsfatzct~ (Oxford: Blackwefl, 198(1);David Odcrbcrg, ""Coincidence Under a Sortal," Pl?i[c?soplzicnl fi?tyvieru 105 (19%): G 145-1 71 ; and "Modal PI-c~pcrtics,Moral Status, and Identity,'?-""l;trlwt~pl?j~
13tilrblicdflbirs 22 (Fall 1997): 25-298;and JeE MeMahazz, 'i"tte Etjzics ttf' Killif[?, chap. l . 35. McMahazz, 'Ilw Etjzics c$ Killit!p, chap. I; Silver, Kcnlnkl'l!q Eden, 69; and Stcphen White, ?he Iljlifjf (tf the Se!f (C:a~z~bridge, : MIT Press, 1989). 30, Muckfe, Karen L)aws<j:,n,and Peter Shger, "The Syngar~~y Debate:Wl~en Precisely L)oes a I-3urmr-rLife fJegiizl'"in Singer et: al., Entbryo Exj~rrj~~z~~.zfatr'o~ (Cax-nbridge: Cambridge Ulriversity Press, 1C)%()): 21 3-22.5. Also, Harris, and Inlntctrfality, 61-65; Michael Locksvood, ""VV11en Does a Life C3Er~rzf.s,Ccr~c~s, Dilerrrntm is;t r"t/tijd~rrzLWedici~re (Oxfad: Ox-Ilietgirr?'?ra Lockwood, ed., ~Jf{>r.a/ ford Urriversity Prcss, 1985): 9-31; and Norx-xlan Ford, kf4terl Did I rt_ft:yit?? (Caz-xlbridge:Caz-xlbridge Univcrsi-~yPress, 1%g), 97 fl: 37. Hrirnnn E:'lnbr)lus:'I7ze l2rhaft. an Assisfed Elej?n~durtion(Oxford: Oxford Uilriversley Press, 1"38Y), 17 . 38. Silver, R~ntakr'stqEden, 64. 39. Sec, far erraizrpfe, j,A, Needhaizi, A History ~fErnltqfolt?yy(New York: Abelard-Schtrxnaz~, 1959); C. Crobsteirz, 'TytacliKerentiation and Its Cor-ztrols,'\Sn'erzt~>143 (1 "34): 64.+650; and Cerald Edelnzan, &Yet.rra/Dclni~l'l-tisnr (New York: Basic Books, 1887). 4f1. Buckfc, ""Arg~tingfiox-xl 1"lotcrltial.'" 4 I. ""Lwis, 13crry,arzd What Matters:>n Rorty, 103,1z.10, the Worst of Tirnes:Yci42. See Fi-erlcfi AII~C~SOXZ, "The Best of T~MICS, cnce7 288 (April 28, 20C10): 62"762% 12.. M , IJlacse et: al., ""T Lyizrphocyte-Directed Ger-re Therapy fitr AL>A-SC:ID: Illitial Trial tlI;test~lt;~ Ager F O LYears:" Z~ SternS~iszce270 (1995): 47.5; arrd 12.ebecca Buckfq et al., ""We~~~atopoiedc Cell Transpfa1-xtatior.t.for the Trcattrtent of Severe Coz-xlbined Inzxnunodeficiency;'"Yel~ Ef[q/nr?dj?f4t"~za/ r?fJWedicirzc.342 (Febrtzary 2 8, 199")): 508-5 13. 43. Mariz-xa Cavazzana-Cafvo e t al., ""Gene 'rheraysy of Htil-xlan Conzbiraed Disease,'? SSdcncc 288 (April 20, 2000): IlnnzunodeGcicnq (SCID)-Xl 669-672. 44. The rnost perspicuous accourzt of harm is devclopcd and defezzdcd by Joel Feinberg in Harrlz 1.0 Cjrhers (Nctv York: C3xfarb University Press, 1%8) ar-rd Harf$t rt) ,Sc[f(NewYork: C3xfarb University Press, 1986). 4.5. Feizrberg, Ibid.; Vrrrfit, R ~ ~ s o tind n s 13ersofls, chape. 15, and John Mmolne, F&iellt'r{q CGc~ods(Oxford; Btackwcll, 299 l), ctlapt, 8, 46. See, for exanz~~le, the discussion of the ""piraciple of parexltaf respor-zsibifity,'%y Bonnie Steirabock and ikon McClax-xlrock,'WI1e.n Is Birth Unfair to the Child?" Hasfirtqs Guter fi?ej?ort 24 (Movcnzl~cr-Decel-xlbcr19tb4):363-369, 47. Lori Arrdrcws et al., Assessi~?qC;cnctic Risk-$:b~tplirnrfz'i~~ls+for Ht2nltlt nnd Sociurl IJolic)?(w~shington,DC: Natiolzal Acaderny of Scic~zces,1994).
48. Sec Holtzmaxil arild Marteau, "Will Gcrzetics Kcvc:llutio~zizeMcdicinc?? and Hubbat-d. arild WalcS, Explodz'tg the Getzc L%fytJz,111 E. 49, ""Upside Risks: Social Co~zscqu~xzces of Bc~zcficialBiotcchnoloa9'5ri [h?7 1 Social ~ C ~ O M S C ~ Z ~ ~qJ' ~ ?the C C SXcw C;ezzetics 1=:,1rl Czrar-ror, eb., Art2 C(;;er.r~s (Netv fJrur-rswick,NJ: Ikutgers U n i v e r s i ~Press, 1Yc34): 155-179, at 157.
Chapter 2 1. John Martirr Fischer and Mark Xkavizsa develop and defend this conception of responsibility in Respot zsibilitll ar ld C(J!~ trol:A 'I l?c.r>r-), r?f'l%fot.al fi?esj?ol2""bility (New h r k : Canzl3ridge U i i i \ ~ e r s iPI-css, ~ 1998). 2. Ibid., chap 1. The basic idea behirill tbcsc two coxzditioas is traceable to Aristotle, AYicttnttlrilc2dztzEthics, Book 111, Sec Tltt2 Ciojtzplet~E44rk.i cclfArisro~lc,Vc>lunres I and II,jonatllan fJar~-.les, trar-rs.and ed. (12rincetor-r,NJ; 12rinceton Urziversity 12ress,1984). 3. Andrews et al., Assr3srir:q Genetic Rbks, 4, and British. Medical Association, F-lutrzi~trCenetia, 34. 4. Clark, 'fl7c ,Yew Healt.rs, 54. 5.J. Mitchcll et al., "What Ui>ulzg People Think and Dc] Whczz the Option for Cystic Fibrosis Carrier Testing Is Availablc,""_Jor-rnlulr t f Afedical C:etzctics 30 (1993) : 538-342. 6, Sec, for erraizrplc,Juha IXaikka, "Frrecdoizr and tile IXi&t (Not) to Knc~v," Bioc+tllic,c12 (1998): 49-63, 7 , IXosar~~ond IXhobes defends this idea in ""Getretic Links, Faiziily Ties, ar-rd Social Eonds: Rights and Responsihi1it)t in the Face of Cer~eticKr~owledge,'" -fotlrrznl (tS&fediciltc~"iirtrd13)hikostjphy23 (Febrt1al-y 1998): 1C)--30, 8. Lynn I"Xartxlla11et al., 'Tfiicacy of Bilateral Propl~ytacticMastectonzy in Woi-xlcxz with a Fat-xlily Histc3ry c:lf Breast Caxilcer," "\'ew Enyla!irlJ>umal 1$,44~dz'crrtc 340 (jaiiluary 14, lWtl): 77-44, and Eli Ginzbcrg, "Putting the Risk of Brcast (Izanccr in Perspective," "id,: 141-1 46. In a more recent stttdy, 143 lvoizretr at increased risk of breast cancer lvere r3B5re.d a prophylactic lziastectoiziy and 79 cllose to have the surgery,At tlle beginr-ring of the study, rluny of the tvorlxen reported high levels of anxiety and otlier psychological probleizrs. Fotlowing the furgeryl hobvever; these probXerxts resolved. See M, D. Hatcl-ter et al., "The X3sychoXogicat Irnpact of Bilateral X3rophj;Iactic Mastectoxny: X3ercpective Stucly tisirzg Qt~estionairesand Structural Interv,iebvs:7Brirish i2/1~arJi~alcfow, sigr~ifica~zt, Hatilizc Megcrs-Heijbocr nnl 322 (jaxztxary 6 , 20QJl):" i " ~ 7 9EqttaUy et al. co~zducteda study showirlg that prophylactic bilateml total nzastectox-xly substatiltially reduces the irrcider~ccof breast calzcer anzong ?voz-xler~with the
BRCA1 or BRCAT! t-xlutatio~z.""Drcast Carzcer aficr 13rrophylactic Bilateral Mastectomy in Wolnc~zwith BR(IZA1 or BKCAL! Mutatiolzs," AVe~uEt?qlatzd 345 (july 19,24501): 159-"14, Jourrlal c~fLM(~dz'cz't.tr 9, Jonathan fJerkowicz ar-rd Jack Srlyder, ""lacisnr and Sexis~z~ ill Medically Assisted C:onception,*' BioefCtics 12 (1998): 2 5 4 % aalrd C.: L, Tcr-r,""The Use of IXeprc3drzctive Technologies in Selecting the Sexual Orientatior-r, IXace, and tile Sex of Children,'7Ibid,: 45-48, 10, See R, I>.?Prry et al., eds., Alzhr3irrlr.r I>ist>tzse(Daltil-xlore,MD: Lilstpirzcott, WiXlkaxrts and Wilki~zs,199"));and A. E. Lang and A, M, Losano, "Parki12sor1'q (f i%ft3di~itfr 339 (October 8 , 1098): 10441050; Discasc:\Vew LF.:'~?qkizrid~k~z~r~i~_~l and JeErcy (IZut-xlrnings,""blndcrstaxildkg 1""arkinsonkDiseasc,'"bid,: 3 X ~ 3 " i " . 1 1. Anzos Shapira, "Wrozzghl Lifc La~vs~ties for Faulty Gerzctic Cou~zselirg: of ,"lediccll Ethics Should the Ilixpaired Netvborn Me Ellttitled to S.tze?"'Jotdr~.rdl 24 (1998): 369-37.5. Also, Mrock, "The Nor-r-Iclentiv Probfel-r~and C;eiietis E-Iarizi: Tlze Case r>fWrongf~xlE-Iar-rdical?~," Bioetllics 9 (1995): 269-276; Ili~ichana~~ et a],, Frorfl Ctlatlc~" C t l i ~ ichap. ~ , t;;JeRMcMahan,'Wror-zgf~~l Life: Paradoxes irz the Moraliq of Causing People to Exist,'Yrz Julet; Colerrtan and Chrictopher Morris, eds,, Ratit~r/rcalContntitnrc.nt arzd LSocinlJ~stl'ce:Essut.,cj)r GPgory Kavka (Canzbridge: Canzbridge University Press, 19988):208-247; Joel Feinbcrg, "Ws-c>~zgft~l Lifc and tbe Coulzter-FactttaX Elex-nclzt in Harrnizzg," "xn Frftedonr m d Ff4v?llttd~rit(Prlnccto~z,NJ: Vrirlceto~zUtliver~ity13ress, 1992): 3-36; I-3eyd, Ger.retCfics, chap. 1; ar-rd Steinbock and McClaizirock, "When Is Birth UnG~irto tl-ic C:l~ild?" 12. In "Be~vare!Vreir~rplantatianrCsenetic X)iag-rosis May Solve Sorz~eOld o j ,Wcdici~lEiflfi~s25 (1999) : Pr-obler-nc but It Af so XXaises New Ot~et;,'"fo~rlrrt~aI 114-1 20, bioethicists Heather Draper and E$tlth Chadwick pre5ex;it a hypothetical case in wX1icl1 two deaf parents deliberately clloose an enzbr-yo with coxzgerzital deafness for ix~~plaxztation. Tftis wottld bc diffiicttlt to jugti.fj,, since the parents .i;vould be intentiorzally fvrcclosirlg opporttt~zitiesfor a future child. 13, This thesis derives fronr Jar1 Narvesones clairz~that we do r-rot have a rz~oraldtzty to ~ziakehappy people, but only to rz~akepcopfc happy He argues tl-iat the ber-rcfit of an act is the good it brirrgs to already existing peaplmr-rd does not irzcltlde the good of people who come irzto existence as a restlit of the act itz 'Vtilitarianisnz and New C;enerations:\Wind 76 (4 967): 62-72, and "Moral Problerxts of Poyrrlation,'"fl?c itikrr/rist 57 (2 973): 62-80. John Iliroonze and Adanz Morto~zdiscuss diEerc~ztaspects of thc nzoral asyrnz-xlctry thesis in "T be Vafuc of a 13c1rson,"Procc>edif;qs r t f tltc Aristi>f~"liafa Society, S ~ ~ p p l ~ n z c ~ z t a Vc3iunzc 68 (l9948):167-1 98.
14. jocl Fcixzberg, in Hann to Otitns; Brc~onzc;Ibid.; Parfit, in Kcizst~tlsatzd Iksons; and Harris, ixz Clonc.s, G~.nc.s,arid inrnri11tillitj5 all dcfitzc harm in conzparativc ttrnrs. That is, a pcrson is harnzcd whcrz shc is nzadc worse off than she wc>tzfdhave been r>themiscwith respect to hcr interests. I avoid usi~rgthe col-iiparative sense of harni w1-ier-r cor-rsideringtvhetl-ier being caused to exist with disabilities harms people, becarzsc; these people tvould not exist tvithout the disabifirtes they Izave, and a c o h e ~ n cox-nparicoxil t car1 be made only between two fhtes of existence.The comparative sense of i1arn-r can be invoked or-zly ixzsofi~ras people exist and have ixzterefts. C>thenvise, we shorrld use an inlpcrsonal sclzse of harm, conzparitzg two disdtzct potcr~tiaflives of two distinct potential pcoplc. 1.5. Parfit dcfcnds tbis pritzciptc in fi?eusotzs arld I)rrsons, chapt. 18, and in as does Jonaehan Glover, "Fuutrr Peo""C:ol-ii~-iients," Ethics 96 (1986): 858 E., plc, L>isability,and Screcnizrg:' in l$.Laslett a-xdJ. Fishkin, eds.,Jfdsriccr Bctu~cerr Acgc Cl,"rt)ctp~ afjd C;r-.ncratr'ctns (New E-Iaven, C:'T':Yzle Universit-y Press, 1992): 127-143, 16. This idea is discussed by Padit ixz R12~sttluand 13crsor?sand by Harris in C3Er~rzf.s,Ger~c~s, n r ~ dIrntrzortalit)}, 17. fi?easotzs nffd I-"cavsons,488-489, 18. Iril "Tltc 13aaadox of Future Ix-rdividuals~~-"l~;tilt~sopl~~~ G IJul~lz'rdfiin 1 1 (1982): 9.3-1 12, Kavka dcfitzcs a restricted life as ""ozc &at is signiFxcancXy deficient in one or l-rrore of the nrajor respects that ger-rerally rmke human fives valual-rle and tvorth living" (I 05).U"et Kavka further states tl-iat ""rstricted fives tyl"ically will be ~vort1-iliving, on the tvhole, for those lvho live thel-ii" (1C15). When I cay that a fife is not '~"ciorth livirzg for a perror-2, X meal2 or-zly a SP~I'P~(?I~) reftricted life, McMahan ofikrs infigfitful discussioril of this and related isstses in "Wror-2$ul Life: X3aracSoxc;s in the Morality of Causitlg People to Exist:hrild in ""Cognitive Disabiliv, Misfortulzc, and Justice," Plzilosophy G I-"ublic4faz'rs 225 (1996) : -3-35. 19. fi?easotzs 6md I-"carsons,chap. 16, and ""Cornnlcr1ts,'"5+862. Othcrs wEro address this pn,blel-r~incftxbc McMal-ian,"C:ogzitive L>isabiiic)r'"2nd "Wror-rgfill Life"; Kavkrt, ""The Paradox of Future Individtnals"; Jal-iies Woodward, ""The Non-Ider-rtiv Vroble~~r,~' Ethics 96 ( 1980):806831; M;ztthetv I-3anser,""WarmG Public AjJ~irs 19(1990): 47-70; Heyd, ing Future People,'?llilosopdly C;cr~~thia,chaps. 4 ancl C,; Bmck, ""The Non-Xdel-xtity X3rohXex-n and f;enetic Harnz'" and Bucl-tanarilet a],, I;l.c>tiz 61trznctv C3I?oice,chap. C,. Xkobert ,4danzs irztmduccd tbc Non-ldcr~tiqProblcx-n in ""Eisteszce, Self-Interest, and the ProbXcnz of EviX,'\\'i?us 13 (l979): 65-76, 20. " h t u r e X+oplc, Disability, and Screerzing," "l1.
21. Ibid., 142. n c the sarne ~zut-xlbcr of people will exist in the diEercxzt 22. Here I a s s ~ ~ tbat outcolnes. This avoids conlplications involving diff>rcnt szut-xlbcrs of people ar-rd llavi~lgto deterllrine which gro~zpis better or tvorse off than others. See Vrrrtit's discrlssion ofb6"Sanrc12cople C:kr,iccs;" "%me N u ~ ~ ~ C:l~oices," ber ar-rd "Different Nunrber C:hoiccs" in Reilrst)rts tind Ptzrsons, 356 fT, 2nd E-Ieyd, C;rnethr'cs. 23. 'Yrangft~llife and the Corrnterfctctud Elerxtent in Harxxtixrg,'" 24. Genet!~l'cs, c11ape2, 2.5. Helga ICuhsc arzd 13cterSinger clair11 tbat "we can, of course, dalnage the cnzl~lyc-, in such a way as to cause harx-xl to the scxzticnt being it will become, if it lives; but if it Izcvcr becoz-xles a scrztic~ztbeing, the elnbryo has ~zotbeen I-3tz'if~ar-rs, and Persons:The Issue of Moral Status:' harmed."' Frorzr "I~ldivldt~als, in IifnDqto Experi-irrtef?fation,82. Furthernrore, I-3arrissays that ""hrnr done at tile 13'"-person (eizzbryo) stage will be harm done to the actual persar-r she beCC;enesfand Irntrzortalconzes, It is a forxxt of delayed-action wr-ongdoixrg.'Y~Io~~t>s, i f y , 253. As I have bee11 arguir~g,persons can be Izarxxted by what \VC: do OT fa11 to do to el-nbryos even if enzbrps do not strictly cpeakirig bccortte persons, 26. Kitchcr provides a helpful ovcrvicw arzd discussion of the gelzctic causes of these arzd other discascs in ' f k eLit)(: to OIIIP. 27. Sec Darzicls, ""The Geszonzc Prc;llcct, Indivitfual Differeszccs, and Just E-Iealth C:are"; Mucllana~r,""Equal C3pportunir-y and C;er-redc 1ntewentior-r:" Srtcirzl Philostylly G IJolicy 12 (1995): 1115-1 35; ar-rd ""C:hoosiilg Who Will f3e Disabled: C;enetic Interver-rtion and tile Moralicy of Ii1clusior-r:7Ibid., 13 (1996): 18-46; and Buchanan et al., I;l.c>tiz C3Ifarzce 61tctic0, c11ap, 3. 28. Silver discusses diEcrent aspects of el-x-rbryoselection ixr Rrrfrakist~I-;rJtarz, 267 f-r: 29. K.G. Edwards arzd j. 13urdy, Hrirnarl Cc?ncel?tionin E/jfi'r~ (Loszdo~z:Acadex-nic- Press, 1981), 373. Sec also Boszrzic Stcinbock, Lifi Bc$~w Birt!~(New YOrk: Oxford tinivcrsiq PI-css, 19"32), and Mary Aszrz Warre~z,,44ttral Starlzs f Clxfi~rd:Czlarcndon Press, 1998). 30, Kitcher 0fi"t.r~a sinl~ilarnrodel to nreasure q u a l i ~r,f fife in ?he Lirxs to CjO~tte,as does Bmck, "Qrr,tfic)r {,l" Life Measrzres in I-3ealtl1 rkin,Sot~cr~i~rz Irirtcie, cllap. l , ar-rd 13ucllanan et al., Fro112 C ~ ~ Jto~ CCb~ojce, Z C C chap, 3, 39. A 2Z"ltectryc$;ift~sfice,83, 152- 2 53. 40. X3adit, Rerzsorzr iirfrrjl Pt?~cotzs,428-436.. 42. X3adit, Ibid., Nagef, Equality iirfrri 13arlr'nlity, 73; Scanlon, ""Contractuatisn1 and UtiXitariazzisln,""and i44tat I$+ O w to Each Utltcr;and KanzIn, l%fot.r~litl:,441jrtalitg Vi~lunzcI.. ICai-xlnzsays that "WC could nzinilnafly cha~zgea strict rnaxinlin theory in the k3Llowing -way: only .i;vhclz what would bc gdined by the worst
off" is a *in that t-xlakcs a real v;tluc sig~ificarztdiffkrer~ceto him should WC forego giving the better-oB-pcrsc3n a rnuch greater gain" "7Cf). S11c calls this the "x~xodifiedrnaxinlin rulc."W~*can interpl-rrt"value sigr~ihcantdigercxzce" in ternrs of cllanges in people's health status 111e;tsured ag*linst:as1 absolute baseliire of a decent r~~inii~rtxi~r of health. 42. These f i ~ ~ r eass ,lvefl as those fitr the incidence of other genetic disor41. ders, are given by Melzlnzan and Iliotkin it1 Access to the G(zt~ottle, 43. "Choosirrg W h o Will Z3e I)isabled,'Y32. Exaphases added. Also, Iliuchana~~ et al., I ; l . c j r r t C3Ifalrct. 61?oicc.,cllap. 7. 44. 13rclzatal Diagnosis and Discrir~~inatiorz Agaitzst the Disablcd.""_k>u~~~nl rtf' ,'lfcfi.nical Etilia 25 (1999): 16-3-1 "i", at 87. What C;ilfanz says about fetuses applies to cx-nbvos as well. 4.5.""Clr3osing Who Will Me L>isabl~d,~' 33. 46, See C;illdszr9s discussion of support &;orpeople with tllala(;seizriain [;recce in "Prenatal Diagizosis7'"84-85. 47. 'T~quallq~" ixa LWclrfttlQtie,cfior;7s,106-1 27. 48. Rer?rakz'r!qIlrit>rz, 9 @*.
Chapter 3 1. Sec Datzicls,_lrut Healtlt c6lPX?, Danicls and Sabin, "Deternrining Medical Necessity' in Mental Health 12racticc," aird Muchairair et al., Fro~tz Chd~lctrto Chnici., chap. 1 arrd 7 . 2, Lercy Walters aird Julie rablcasscssl-xlcrtt of this issue in arld ~~hz'lorophy ""Hurnaxil Gcrzc Thcrak9y:Why Tlraw a tinc?'""ounzal (zfrW(~dicirzc 14 (Dece~ziber1989): 682 -6%. 1.5. "Risks Inherent in Fetal Ger-reTherapy," AY~zt~l"e" 397 (February 4, 1999), 383, 16. YA-X3ingTang et al., "Genetic Enhancenzent of Learnix-rg and Met-nory ixr Mice,'\Vature 401 (Septer-nber 2, 1999): 63-49,I2egending a n the level af or-ze's coglitive ft~nctianing,this type of genetic ixrtervcntion colzZd be labefed as either "therapy" 01- "er~har~ce~-xlc~zt,"
17. Sec McMahan, ""Cognitive Disability, Misfortttlze, and Justice"; Buchana~z,""Cbooshg Who Will Be Disabled: Genetic 111terventiorz arzd the f~ to Cjloice, chap. 7. Moralit); o f Xnc1usion"";rzd Bucfialzan, et al., F r c ~ Clta~r.c. 18. IXawls, &tr or-re,criticizes uti1it;zrianisnl far this reason in A ?heor]) 4Jt4stict~,27 ff. 19. See, for erra~nple,G.Q, Maguire and EIfen McC;ec, "Iiz~plantableBrain Z ~ P I 29 " @axnuary-Fehrttary 1999): Chips? Time for I>ebate:%t~sfitl;qs C ~ ~ I ~Report 7-13, 20. Access k~ fJw Ger~ttrflc.,124-1 28, 21. Ibid., 125. 22. These rates o f incidcxzce (thottgh not the cost of treatnrcrzt) are gik~cnby Mchlz-xlarr and Dotkin, Ibid., 41. 23. Sec Czlark, ?'he Xew Hculen, chap. 9, "Gene Tlzerapy for Czar-rcer,'" 134-2 60. 24. Jon anieIs,Jtdst Health Ctzrc., 32, Wralters and Pafx-nzerpresent this thought-experizxex~tin Z7te Etlrt'cs (tf Hednlan Cknc. 'l"lilc.rq-)~, 123-128. As they szotc,jonathan Gfovcr ixztroduced this idea in 15iImf S ~ r qflJecyfe f Shotdid 'l%c.wBe? (Harnrondsworth: 13enguinr, 1984).
32. Drawitzg on the work of tir>acl trilling and Chaz-lcs Tiy1or, Cad Elliott discusses cognitive and agectivc cxzha~zcenzc~zts that undcrnrine what he calls the ""ethics of authctzticiq" "xn "The Tyranrzy of Happiness: Ethics and Cc~sin 13;irens,Enlratzcitv fid~tttnTktiific,177-1 88. Also rnetic Psycllopharnracolo~_~)i," in relewne to this issue is Harry Frankftrrt, ""Iclentificat-ian 2nd Extcr~~ality," Frankfurt, The Ifclporttztzct. qf l.l/"l~nfJ+k Cl~zrc.ilbotdr (Nctv York: C:aizibridge University Press, 2989): 58-68, 33. !>avid and Clare f;alton, ""Francis Galtan: And Eugenics To&y'"i~l&rsza/ qf i2/1edic~lEfjtics 24 (4 9%): 99-1 05. Atso, Buchanar.t. et al., I;rt?rfl C;","hafrceto Choice, chap. 2. 34. Sec, for exalnple, Daniel ICevlcs, 112 the. AYtzna~ r!fEf%qrnia:GPNC~ICS nnd tl'rr iisi*s of Hclrflnn Heredity (New York: A2fi:cd A. h o p f , 1985), and Troy Duster, Bci~kdnnrtct Eti'qt7nics (New %Irk: I;tr~tztledgc,1W911).Cf. John Wag-rer, "Gene Therapy Is Not Euger-rics,'"Xafulrc. Ccnere'cs 1.5 ( l997), 234. 3-5. This terlzr originally was coined 13y Joshua Lederbcrg in "Molecrzlar Iliialow, Eugenics, and Eupl-tenics," "Vafure 198 (4 963): 428-429, Janzes Neel efal9orates further on this idea ixr ""Lookirrg Ahead: Sonze Gex~eticIssues of the Future,'7I)1.ipec1ivcs ist Bi~lt;qyand i2/11adi~ift~ 44 (2 997): 328-347. 36. "Which Slopes Arc Slippery?" in Williarns, ,jldtzkl'rg S~.nse rtf' Hclnruaity (Caz-xlbridge:Cax-xlbridge Univcrsi-~yPress, 1995): 21 3-223, at 213. 37. Ibid., 213. 38. See Trrxdy C;ovier, "What's Wror-rg wit11 Slippery Slope Argrxnrer-rts?" C2(~fjndr'an Jounlal of Pltilostyj?y 12 (Tune 1982): 30.5-31 6 , Atso, Wibrer-r van den Berg, ""The Slippery Slope Argu~zicne,"Ethia 102 (Clctober 1991): 42-65. 39. Here 1 foXXow CGovier's formtzXation, 31 2 . 40. See E. Berger and 23. CGert, ""Genetic I>isorders and the Etl-ticaX Status of nfzd I)l?r'Easophy 16 (1991 ): CGerrm-Lirre f;ene Theraysy;""tpurtld (tf i2/1~dici~le 667-683. Also David Res~zick,"Debu~zklngthe Slippery Slope Argut-xlcnt About Hut-xlan Gcrnr-Line Getze Thcrapy,'7Xbid., 19 (l994):23-40. 4 I . 'i"tte Livc.5 to f=c>nre,202. Sec also Glc>vcr,15il$at Sort of IJ~ycyfc.Should 'I'here Be?
Chapter 4 1. lax1 WiXnltzt et al,, ""Viable Ofiiprixrg Derived fianz Fetal and Adrzft Marrtxna1iar.t.Cells,'\Y~ztz.ti.c.385 (February 27, 1897): 310-313, 2, Cfonirlq Hlrrjrua B~irlqs:Report arld fi?Iy~(~fifil1~nd&tI'Of~~ r$-t/?i>LVt~tiotzu!Bioet/zics Advisory C(~8clttlisriatl(lXocE;~.iille,MD, 1997). Jarncs Childrcss, Susan Wolf, C o u r t n q (IZarnpbcll,Daniel (IZallaha~z,and Errick l%z-ctzsdiscuss diKerc~ztnzoral
and XegaX aspects of the Kcport in "Cloxzirtg Hun~alzBeings: Kcspo~zdingto the National Biocthlcs i"?ldvisc>ryCc)nzlnissic>akRtport:Wastir?qs Cetlti"~R[-"port 2q(Seytcnzl~cr-C2ctobcr1907): 9-22. 3. Notetvorehy critiques of cloning r3r-r these gmunds are ogered by Lean Kass, "The Wisdr3111 of Rcp~gnx-rce: W We Should f3ar-r the : I;towizrar-r & Littlefield, 19981, and Martha Nussbauizi and ss Sunstein, eds., Clofrc~5czlatJ C;","loizru,c: Facts and Ezttfasies Afitttat Htzfttafz C;","lorzit;g (New Y0rk:W.W. Nortoxr, 1999). S,'TthicaX Aspects of Cel-xetic Coxrtrols:\Yel~ Ill-r;qland_forinzal oj" iMt>dil-r'rrc 285 (1971): 776-783, and ?'he Eti~icsof' Cerletir Ct~~~trcjl: E:'lzdit;qEl[~prodzactif~r. Eloulettc?(C;az-dcxz City, MY. Axzchor Press, 1974). 6 , This is tbe sccoxzd forl-xlulation of tbe categorical irnpcrativc, The first fari~rtxlationsays: ""I~ught never to act in such a way that I could r-rot also will ~ Eitldrtdations I$ tllc. Lifefathat ~ziyxzraxirn silould be a ur-riversaf law."' F r o r ~the pltysrc?; of i%f(~r~tls (1785), trar-rs.L.W. Deck, secor-rd edition (New York: Mac~~riffan, 199O), 429 for the cecortd fornzulation of the categoricaf ir-xlperattve,402 for the first, Page reference3 are to the Royal Prussian Acadexrty edition. F. M. Karrtxrt ofikrs a collterrtporary defense of the Kantian notion of a perror-2 as an inviolable trzd in itself in ""Nonconscqupr~tialis~-xl, tbc 13carsoxz as an E~zd-irr-Itself, and the Significa~zceof Status:? and in ,'lfc?rolitli-xlthe XcgaX ozzc at issup hem, that clo~zingshould not hc perinitted. 2'7. For discrzssiorr r>fthe diseisrction between negative arrd positive rights, sec, for erra~i-xple, Klaizr~zi,L2.foruliry,,li/Iortalit)~,Etlunze 11: KljtTifts, Duties, atzd Strntus. Jr~dithJarvis Tholi-xson, i"lw Rc2t~lrrzqf Riqlrfs (Caizrl?ridge, : I-3arvard Uilivercity Press, 1990). 28. ' T h y We SX~otlldBarr Hunzall Clorrisrg,'2 123. 29, ""Genes, Ex;ivironr-nent,and Personality,'\Sci~~z~~" 246 ('jrrne 17, 1994): 170QJ-1701. 30. "Whcrzcver the Thvaitz Shall Mcet,'Yixz 'Ihe Scirncc~3"j";""X)rolnisc and Pcrilil,"Y2-54, at 54, 31. ""The C:hildSs IXiglic: to an Cjpen Future," in W. Aikerr and H, LaiFollette, atzd State Z%u~t>r (Tc3tc>%va7 eds, , JVhose Child?: Cf~ildrc2n"srI't1/t NJ: Itcc>%viirdtr~ 81 Littlefief d, t 980): 124-3 53. 32. See, for exax-xlpte,the ceries of articles ixz "The Promise of Tiss~zeEngirreering,'Ycic~nf~fic Anr~ricala,April 1999, especially !>avid Mooney and Antorrios Mikos, 'Growirrg New C)rgans,'%60-65. There is a &rk side to this tecb11o1og-y as well. Arrdrews and Dorc>thy Nclkitz explore how tissues, cells, and gelzcs can bc harvested and turned into con~nzoditicson the opcrz t-xlarket in
U 0 4 Urlznar: 'f 'tze L%ft~rk~t~f;lr J - I ~ l n a f2 z 'i-cst-leIn tJw B i ( ~ t c J o l A qg e (New York: Crow11 Publishers, 2001). 33, Ibid., 63. 34. See IXos-rald E-%artet al., "Born Again?" 7116 ,Scinzct.s 37 (1997),""lt)rc>iirise and 12crif,'"47-5 1. 3-5. IXeported in the London Srtrrday Tinzc.s, Cjctober 19,1997. 36. See Stcve Mirrky and John Xkennie, "What Clox-zing Mearls for f;ene ?'herapy,'3cienf~ficAt~teric~1~1,J~1~1e 1997: 122-1 23. 37. '"The Wisdol-n of IXep~ig1lance:224.
Chapter 5 1. Sec, far cxaiiiple, 281, 1303-1 304. 7. Xu-lkong Jiaxzg et al., "Telol-xlerase Expresslosi in Hul-xlan Soi-xlatic Cclfs Does Not Ii~drzceCzl-rar-rgesAssociated with a Transformed 12Erenotypc,"Nt~iur~ (;;rmCtr'cs21 (J'znuary 1999): 111-1 14. 8, D, 12ro~iiislc>w, "lor-rgevity and the Barren Aristocrat," Xature 3396 (liecel-xlber 24-3 1, 1998): 719-720. Also, R, Westendorp and T Kirkwood, "Human Lor-zgevity at the Cost of Reproductive Success:? Ibid., 74.3-744. 9. Ceorge WiXliamc, 'Tr)Xeiotropy, Natural Selection, and the Evolt~tionof Senescence," E v ( J ~ ~I ~I(1957): ~ o R 398--411. This hyl3othesis is elaborated further by Ncsse and Wilianzs in FM?-),FW Get Sick: 'llwA\rcw Scic.rzc(>of' ZJumjirzia~ ,'lfcfi.nicit.tt.,and ""Eolutiorj and thc Origirls of Direasc.'3ee also Ewald, Eztoft.rfion ~flt~f:kci(ious Dist.rtse, 10. ""Evolution and the CTrigiils r,f Disease," 86. As ~iier-rtionedin chapter 1, tl-iis idea derives fro111Ther>dr,siusDobzhansky 13. CGerald Pier et al., ""Salr-nonella Typhi Uses CFTR to Enter lntesti~lal Egithefial Cells,'\Vnrl-fr(z B 3 (May 20, 3998): 79-82. 12. tWzy I& G(zf Sick, chap. 8, and ""EvoXutian and the CTrtgirrs of I>irease,'" 91-93, 13, fi?easotzs n d l-"c~ssjns, 486 E. 14. Ibid., 486, 1.5. ""Evolution and the C>rigks of Dise,zse," 92, 16, IXusscfl Ii:r,ss, ""Atherc>sclerosis-r Inflanr~iiatoryDisease:' LV17fuEngIat.zdJouuzaI c?f,\/ledicitle340 (January 14, 1999): 115-1 23, 17. " E r i ~ l ~ i t and i o ~ the ~ Origirts of X>isease,'Y2. 18, See Reasor?sar~dPl>rsrtlu,Appendix F. 19, Genetl~l'cs:iWclr~l1ssuc.s is;t flae C;r(oafion @I2ctyz2p, (34 tT. 20. Kainrn cl-xlplr)ysthis principle in her axzalysis of allocating scarce t-xledical resoktrces ixz l%foralitlr,~%lor#tzllfy: liiol~~~.zle I: Deaift and bi4?orfl to &vc liro~nI f (Oxford: Oxford University Press, 19".33),part 111. 21. See Tho~iiasE-Iurkrt,"Value and 130pttlation Size;" Ethics 93 (April 1983): chap. 17. For discrzssions of the issue 134-3 47, and Vrrrfit, Rct~sorrsatzd 13t~norrs, oE5airr-ressas it pertains to the yotxr-rg slzpporting the ofd, sec the essqs in 13eter L,aslett and Jal-xles Fishkiri, eds,,_lrastiw Bcfuj~nAAguC;n,t-l/~s and Gener~tz'or;7s (New Havex;i:Y~leUniverri-~yPress, 1992). 22, See Cairtls, itrlnffers qf LiI;. and I>catlt,chap. C,, and CGarrett Hardk, Lcivirt,~ f/iTir!~ZfzLz'tlzifs(NcwYork: Oxforcl Univcrsie)i.Press, 1995). 23. "Upside Kisks,'Y162.
24. This idea is dcfc~zdedby Daxziels in his prudexztiat Xife span accoktr-rt to deterl-x-rinca just distrib~ttionof heat& care, infrisf HcaEtlz Clarc>,and Aft! i ,Ify l)arc>~jfs' Kc>n,NJ: 13rincetc>nUrzivcnrsiq Press. Arjarb J., et al. 1999. "Dinrinishing $;teeurns fl-01.1-r Mutation Supply Rate in Aserrrz,tl 130pttlations.",%inzct. 283 (janrz,try 15): 40+4OCi. Armstrong, L). M. 196%A A,Wrzf~riali~f irZ?coqf -)r$ L2.find.C:aiiibridge.: C:arzrl?ridge University Press. Arrxtstror-zg,Cregoryl et al, 1999,'Trends in Xnfcctiotls Disease Mortality in the (tf 1.1'14 A~~iericiirn LWcrJicizl Ul~itedStates ll3urirrg the 2O'~<entury." "cJ(?urnlal Assodatiilfl 281 oanrtary 6 ) :61-66.
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Ascbrremd, 79,It11 Alyrlullcrtry theris, Olbhh ArIierosclerosis, 154 Au\tirz, C. R., 27 Autologous hep'lcocyte transplantation, 130 Autonoi~iy,108-109, 111, 11") 126,127, 132,127, I34 Aydla, An~c%a. 126--127 Bacteria, 20, I 50, 152, 154 antitliotlc-resistant \trains of, 15.5 R a ~ dlfatf-kid, , I Yil(n7) BAPI". Sf*eBeta-arl~yloiclprecursor proteltz 13 cells, IS, I54 Befirtvior modification, 36 13enefitihdrln Issues, 2,5,9, 10, 11,34-35, 35--36,3X, 60-66,72.94, 110, 1 19, 124,155-156, 157, 1X%(n13), 1X4jn25) tnenefice~xce,59,87, 88, (933, (97, NX, 112, 134 cc)i1113arative sertse of Ii~rrn,183(n14) rnagnltzlde elf harm, 6O,75 ni>irll~leficence, 511, 51, 52, 59, 011, 04, 66,6X, 80,X5,87, 111, 131-132, 148, 1%. 173 and r~ghts,55-56 Beta-axnySord precrrrsor protein (TZAPP), 7 2-72 Riotechnolom, 9.38, 112 Bil7olar dhorder, 59 13octles, 21-22,29-30 Bone-~l?~~rri>\v transplntdtion, l 11, 126-127 Bockl~~,Jefi?e)i,100 13oucIzarel,Thon~as,I32
13rdm, 21, 22, 2X,90, 147, 164, 165, Cloning, h, 1l h, 117-1 35 17X(n2X) and dddptive evolution, I D 3 ,124, 128 h a m cfirps, 98 of body parts, 128-1 32, 134, I92(rt32) hraln da111dge. 1(17 evolutionary inlpdct oi: 123-1 24, 132 hams of mice, 95 failure/success races, 120 and Inexr-tory, 168-1 69, 17U rr-ttthods of, 1 1 9 - 1 20 See c~lsoCerebral cortex; H~ppoca~~ipus; reasons agaxmt/for human clonlng, I 18, P;leurc>transmtclers;Syi?,~p%es 123--129, 132, 132, 128-132, 133, Bmzv ?li%ijdl.$r!d (Huxlied, 118, 119 134, 102Cn2h) Britain, 117, 134 and reducticznr in brrrt~defects and Bwck, Dan, 3-4, 125 dhertre, 123 13uclzanan,N e n , 3-4, 8 1-82 therapeutic, 1I? Buckle, Stephen, 179Cn32) and unexpressed traits of ciionor, 131 13~311,Georgc W, 137 uses of-,11.8-11% 1126 Clol~ingX3t-c>l-tibie~ox~ Act: of 1 1063, 117 C'~Udhdn,DanreI, 160-1 6 l 66, Cognxnve deveIopmtntlcnhancen~tnt~ Catmexlc.Jeannc, 15 1 l(17 Ca~~acI'r, 117 Cc)g~:nltivevs, physical firnctioning, 73 Can,~v~n dlccase, 66, 101 Colitrts, Francis, 12--13, 1"7h(126) CancerCs), 12, 13, (92, 1112, 115, 135, 139, Cc)i~ipetitivegoods, 106, 1117, 108, 112, 146, 147, I78jn23) 151,159-I60.151,172 braln cancer, 92 Cc)rtsanguinity coet%icient,1l 1 "oreast cdncer, 13, 14, 18-19,50, 54-55, Cont;ciuttsness, I 0.21, 22,24,25,2"3 61, SA--57, 1 X I (nH) 97, 132, 164, 17#(x-t2X) colon cancer, I 4,91 coIlect.rve, 39 envirox~rncnulc,rmes of, 1H c~l?sclouspresent, 1h3 o~~arian cancer, -54 29, 31, 1hX, 170 self-con\ciournetc, X?, rcorr-tacll caicer, 154 Col~sent,2, 39, 59,93. 1311 Car\>ondioxide, 1.59 Cc)rtsequer~tialisi~~. 4-5 Cc~rd~ovdsculdr disease., 125. See a1.w Heart Costs,79,99, !()if, 101, 102, 105, 106, 158 disertre socidl costs, 107, 1118, 109 C'lreers, 53. 105, I06 CKEWI. Sce Praterns, cyclrc AMP res~?~nse. Carriers, 19, 54,123, 125. Sea 4~li.o elelltel~tbr~~ary Xnherltance, attto,ume~lrecessxve CVS. See C11orionrc vrU~rssarr~pling Categancal imperatnw, 19(J(nh),See riE50 Cycexc fibrosis (CFJ, 13, 1") 2211, 30, 31, 32, Mea~tslends 37,54,09,82,7.5.94-95, 115, 123 Celera Ccnorr-ttcs,12 nuntbers aRtcted, I01 Celb, 147-148. See (tbuEnlL>ryos,ceU severity of: 66,f;K drtferenn~tionin; T-cells; irtad~rAging and typl~u~d fever, I52 Gentel-tarians, 135, 1.5 1 Gembra1 cortex, 2 1,24,26.27, 169 flaniels, Norman, 3-4, I A, I 02 fibrosis CF;. See CYC~XC De,tfi~ess,1X2(n12) Chadwxck, Ruth, 3 X2(n13) flent,Jarnes, 92 Chtldtzcarix~g,1S1 DeontoloGgI5,See illso Meanr/en& Ghorronic v i h s sa~~iplrng (CVS), 67 n e Silva, Alhantl, 33,X"f 92 Cli~r~ate chaxlges, 159 Di~ttece\,19, 11S,2 17, 136, 154 Clinton, B1l1, 117 type 2, 14, 1111
Diet, I 4,36,54, l l I dantage to, 139, 146 Dityerence principle, 77 of rtiitochondr~(933-94, 129 flignlty, 118, 119, 125, 126, 127, 131, 127, repair nlecl~dnis111~ of, 124 Dobzhan%ky, T'heodt>riur,It 1, 14 134 flirl-unishing 111arglnaI.value c?rfhfeyears, flolly, I 19,123-124 158, 1h2 Dopatltinc, 16, 3 1. 60 flisabrlity, 16, 30, 70, 137 flown syndmrne, 21,30,6X, A") 96,%, 123 disabled people, H 1--H2 Discrim~n~tion, 51, -53, -59.77, X1,X2, 1lt 1, Draper, Heather, 1X2jn12) 1 3u Duxlis~n,22--23 'tgainst the elderly, 160 Duchenne r~itlscuLrcIystropliy (DMD), 21, 50, 5'7, .58,64 fliseaseid~sordcrs,1 , l l, 12-21, 35, 138, numbers akRicted, 101 152, 1C71b-161 anlbigulty of genetic component m, 14 flworhn, Ronafd, 4 autoirntnmx~edisease, 1S, I t M, 139, Econornlc Issues, 84, l I 4, See a1.w Costs 155 Edtrcdcion, 18, 106, lO"7 11 1 chronic, 101, 13.5, 154, 1SS, 173 and clc-tning,124, 123 Edwards, Robert, 07 cogt.~ierlte./~fi~eccivcs 89-90, 107 Egalicarlztn prmclplc, S1,77,78, H3,Y8. See cIef"Initiori\ of, 15--10, 17, 102 illso Eyuahtyi~nequ~tht?, Eisenhcrg, Lean, 123-124, 132 dlsedse vs. ~Unessidisabrlity,I 6-1 7 and epigel-tesis, 14 E:'r.soutlrdr-t l; Brtrud, 129-1 30 monogenic, 13,37-38,53,59,AAk, a, Elderly people. 158-15") 159-I 60, 161. l(J1, 115 See t~lsoA g i ~ ~ g l l l l t l t ~ ~ l ~ t ~13, ~ l101-I d f , 02, 115 Exlibryo,, 28-2% 31,34,36, 50, 61,81,93, objectxv~sticonscrt~cti~~~~c ccb~~ceptio~~s 158, 1"7(1-t32), 184(1125) of, 17 cell cI1fi%rex:17ti&tim in, 27,28,29, 33, 9CJ. onset of, 30, 31.37,66, 69-70, 70--71, 95,131. 2-47 72, 74,75,76, 148, 149, 153, 1-55, choosing st~tic>i-tg, 57, 5%I ,X l-81 158,162,172 cloned tiom p,ttients94orrmtrc cells, I I? potygel-tlc,13, 189 embryonic germ cetls, 147 pEmdture ~ n f e c t ~ o1-50, u ~ 173 crrlbryan~cstenl cells (ES), 117, 1IX, 128, 129, 134, 136, 137, 138, 146, preventio~~/~reac~ttex~t of, 14, 17, 35, 37, 3")8~,88,X9,111,112,1I4,131, 147, 155 132, 157,158 gro\ni-ixlgp ~ r t i ~131 f. and rertse of self; 30 headless frog elllbryo, 131 severlv of, 66, 69,74,75,7$1,H,3--84,Y.5, rnoral smttxs of, 67-68 Sf*eidso C913ligatio11, 'tn3 reverity of selecting for sex of, 57, 59 disease;Worse-off-prlarlty principle cerm.tnaclon c?rf;I?,35,37,5S( .54,5X, and time between onset A I I ~dedtli, 75, (i2,6.5,06, 07-h8,70,72,7~5,76,82, 83, X L 92, 1109 162,164, I72 See also Cenn-line rn'~niptxLdon;Xrr types with gellerlc cause, 13 fliirllrslt).:See Genetic drvcrsity vitro fcrt~lizacion DMD. Sec Duchcnne lltuscsrlar Emergence, 22,2"3 dy\trc)phy Enlc>tion\,(95--(30 DNA.6, 12, 14,33,Y1,117,1l9,1123,124, Employment, 2,S3 131, 130, 131,135 EnJt>r~ietrioxiil, 1li
Environmenul Gctors, 9,13, 14, 18,39,9.5 ddapting to chdngmng, 123, 124.128, 132 and clc-tnlng,123, 121, 124, 132, 128 and lliental states, 23, 131, 132, 164 2nd personal tdentrty, 22.29 and plzenutypes, 28 2nd prevtn tin& tredling disease, 111-112 2nd schizophrenia, 30--3l,hO, 112 rocid entiironment, 111-1 12 Enzyme replacement tlzerdpy 79, 101 Epige~-te\is,14,28,2"3 332, 110, 1331 Eq~~llxtyixnequdl~ty, 37, 77, 87,94, 9% 1100, 106, 109 and fa~mess,107-10% intergeneracicznal, 155-1 h l Scc also Egali taran prmcli~le EquJ protectiox~princlp'le, 129 ES, Scc Elnbryos, e~llhryorlicrtem ceUs Estrc>gen,18 Ethical issue\, 1-2. Sce d s n Moral hwes Eugcnrcs, negatic~iposxtive,109- X I 4, 132-134,135 Eu than'~sx,~, 71 Evolutionary brolog, 4, 1(l-2 1, 14, 15, 18, 19,20,38, 173 2nd clonmg, 124 and ev~tution~iry medicine, 1-52, l li 1 and Illernary 168-I 69 Scc also Natural \election Fairxless, 78, 82, 94, 99-100, 10U-101, 10.5, IOfi 2nd equ6t1ir?;1t 17- 1OH interge~lerational,155-1 6 1, 172-1 73 Fantil~;tlh)perct~c~Ees;cerole~r~~a, 92, 1l S Feinberg, Joel, 04, 127, 1X3Cn14) Fertihcy drugs, 6'7 Fernre\, 26,27,28--2% 331, 32, 34, 36, -50, 61, At(, 81,89, I79(n32) second-trirntster, Y2,YS terlnination of; 1"75S(f,54,62 Fletcher,Joseph, 11H Fortil fuels, 159 Fragile X syndrorx~e,30, 96 Free radicals, 136
"'Furies, the Meatorious" (X.lorges), 170 Ft~ttlrepecqlle, 3A, 37, 3% 62, 64,%, 135, 138, 151, 153, 155,156-157, 173. See ill30 uilder Interests: C f bligation Future sejvcs, 23, 162, 164, 166, 1 6 F I 6 8 , 171.173
Cducher's disease, "7, 1t 1 l (;etsinger, Jerre, (92 Cenerdcio~~&ll issues, Sec F,tirx~ess, ir1tergerleratlt>17dl Genes, 9,I Ii) IrEKCAI/URC:N, 13, 50, 54-55. 56, -57, 181jnX) and disease, 12--2 1 , 149 and early-/late-onser: diseases, 149 ge~~erd~ip~~rtxcsrldr levels of operdcxolI, 1I Itlteractions ~imo~lg, 36, 39, X, 93,"IS and Inexr-toty, 168, 169 oncc)ge~-te\, 1351-1 46 and perronal ~dentlt):2X,29-38 pteiotropic-gene hypotherrs, 149, 152-155, 173 recessive. S ~ Inheritance, P autoso~x~al recessive turnor stxppressor p59, 102, 139, 146, l53 Gene cherd~~~fj; 15, 17.31.32, 33, 36, 56--57, 65,79, X6,89-1112 access and aUacdtron xssues, 99-102 dedttis resulting from, 92 vs. genetic enhancement, 102-IOS, 110, 112, 113,124 and 111entd disorder\, 95-97, 98-99 and pre,e.rvmg/chanw idcxltit-): 94-99 and rlippery-\lo3pe Argutllent, 112-1 14 11-1 utem fetal, 90,92, 95 viral vectors in, 91-92 Genetic deterlmn~sm,12.9, 131, 132, 128 Genetic disc~rclerr,early- and Lte-onset, 31 Gcnetrc diverslcy, 39, 119, 123-124, 125, 2 28,132,135 Gcnetrc enhancement, 1,2,5,37,34,7'7, 86, 87-88, 89, 95, 102--109, 133, 134, 157, 158, 173, lXW(n2h) enlrancentex~tofvirrt~oustraits, 108 and ge11etic lottery, ll1(i--107
2s morally ol>jectionable,I V1 unic~ers~tl accetc to, 1(17 See cdso irta&rr Gene tkzcrapy C;enet~c~nform~tioz~, 36, ,51),.52,58 Gcnetxc xntcrvcntian, 1,218-39,85-86, 131, 146, 148, 150, 155, 158 co5cs, 79 2nd enhaxlcentent of c,rp~cities.See C;enetic enharlreme~~t 2nd personAI tdentrr-y, 29,31,32--34, 34-35 See czlso Gene therapy; Gcnetxc tesrrng; C;erm-line manipuhtion; Life rpm Genetic Iottery, 100-101, 106-107 Ccnccxc research, 101, 115, 134, 136, 137, l46 Ccnccxc screenmg, 36, S1--52, S3 and treatable disorders, -54 Ccnccxc re,ting, 17, 35, 3h--37,52,53, 54, 6.5, 60, 07, O X , 72,84, X7,X9, (32, 111 vs. genetic screening, 5 1-52 t\NO forfllt ot; 50 Genotypes, 14, 29, 1llo, l I I , See &a Pel~etrax~cc Gcr~~i-hne rnanipuIatxm, 36,249, 90, 95-94.147, 148,153, 157,173, l %S (1127) C~llnrx~, Lynn, X 1 C;Iover, f onatEra17,03, 179(1132) Grectvcs,iVlt1, 17X(n23) C;rowtli hormone Injection\, 1114-1( 5 C;ulfiver"shgfn.cls (Swift), l 64-1 65 Hardy, G. H., 185tn3.1.) Hztrr~s,John,179(1132),192fn21) Hal~iking,Steplien, 73-74 HztyA~ckIirntc, 135, 136, 191(n 10) Healtli, 15, 19,36,37, 77,7X,79, 102, 112, 128, 133, 134, 149, I IXri(rr48) coqrc>mise between health and diitertre, 152 Healeh c'rt-e, 101, 102, 160, 161. See clkit M tdicd treaczrient Heart diseaw, 13, h%, 102, 1I S, 135 Hel~~c>phiIia, 21, 57, S, 92,1l5 Heycl, I>~vid, 3, 64, 157 Hick, JoIin, 190(11)
H~ppocarx~ptxs, 2 1, 169 HIV-AfI>S, 102, 150, 155 Waltzman, Neil, 13, I4,75 Ho11?~r\es~,dity, 59, 118, 128-129 Hulllan bemg, concept of; 22. Scc~also Persons, vs, hulnm orgdnts~lts Hulllan Gcnorne Prqect, 1, 12-1 3, 176(n6) H~1ntington3disedre, 13, Xi),2 1, 50, 32-53, SX,hh*1l5 Cdtlre 52 onset of synlptorra, 69-?O,?ff-?l, 76 H~~rka,Tho~lla%, 165, 1X5(nn 32, 343 Hurler syndrome, 66 Huxley, Aldous, 1 I X Hydroxyl radicals, I23 Hypertexuro~~, 16--17, 19, 80, 101
0e
1dentic)i2,4,9, 10, 1I . 90,ItE, 135, 169, 17K (n2X) b~olog~cal/persandl, 21-25,20, 65, 131, 132, 12% 135,103, 167. See ~ E I M Perrans, vs. human organlsnls and cogt.~rerlte./~fifective disorders, X9--9(J and continuity ofxxlcntal states, 163. Sce t~/sitf)ersons;Psychological cc~nr~ectecineuicc~z~tinui~ and expertence,/rnexr-tories, 3 1,33, X9 and extendirig hfe spa17\, 137, 13X-13C1, 162, 166-16?1 171,173 and gene therapy (334-(29 Sce czlsn l"crsuns Intrnort611ic)iof cells, 147 llnmune system, 33-34, a, 92,1I?, 12.6, 127. 128, 129, 130. 146)1S1 , 153-154,154-155 auroirr-ttnunc diseases, 1S, 104, 139, 1SS enhancing, 103 equdiibr~unlin, I34 ~rtimu~-ti)deticiency, 33, See (tbu Severe conlb~netl~~ia~~rtnodeticiency rtiAdrlt~rjatoryresponses, 154, 1SS xnnd tel~daptivecomponents of, 14-1 S rr-texr-toty cells in, 1 5 Immu~-t~z~tionsir,~~iccinet~ 1113, 1-54 littpersor~dlcontp~rdcixreprinciple, 4, h l , 63-64,?6-77,XO, 85, "IX
Income, 18, 105, I06 Inequahty. SCe Equ,dity/ineclu,dity Infertriht-y,12% Infl'ition, 1611 I~~her~tancc abl~orznalitiesXIOCinheneed, h8 auto,orrml dorn~ndnt,2.0-21,52, "7, %, 12") 'tutosc)mdl recerslw, l(>,2(1," 33, 54, 73, X3.91, 123, 12.5, 12%--130 Institute of Medlciae Cc)i~xslitteeon Assessmg CC;enetxcItrsks, 36 Insura~~ce, & -53 Intelliger~ce,Y -5 Ixztenticznr, 33, 89,9S,Y6, 126, 129, 163, lcitjl 168 Ixzterects, 10, 11.34--35,56. h/l.h3,hcF, 65, 85, 124, 127, 130, 129. 183C1.114) of future people, 124. 137, 148, 173 prudential interests/cc)ncer~ts,52, -53, -55, 84,138-139,Ih2,166, 169,1I.a, 172, 173, 1954n27) Intergeneratxonal; equahtyifairness, 155--161, 172--173 Intxma~y~ 56, 129 1x1 vitm krt3hz;taan (JVF), 1,36,5C1,57,59, 67.80, X3,XY, 93, 117, 129, 134,137 IVF. Sec In vitru ferribzacrox~ 1,
Jews, Ashkcn'~z~, 53-54, 1l 1 Johnston, Mark, 179(n3%) Justice, 60,64,64, 82, X5,87,XtG utilitarian argzsrnent for, 97-9 X Katltnt, F. M,, 1Xh(n48), 190(xrh) Seij also Mc=tm/enc$t Kan tiann~ll,5, 1(33(l(n6). Kas, Leon, 133 Kavkd, C;regory, 39, 1-59, l Ili 1, 1X3(nlX) K~tcher,Philip, 3, 17, 1l 4 Kuhse, Helga, lXrC(n25) Lee Ho Von, 120 Legal issues, "7, 1I?, 131. Sce czlsn Obligdcxol~,legal Letch-Ny1i;rn synclro~~se, -50, 60, 70 Lcukxr-tt;t,126--127, 130 Lewis, Davlil, 167, 17X(n&?X)
Lrk plans, hC1,Y7,132, 127, 162, 165, 167 L~fe,rertset of, 25-29, 163 Lxfe span, 4,23,5?,6243,64, 66, 135, 135--173 knmle Ioagevity, I5 1 rr-toderate vs, substar~cialextex~stonsslr: 171,172 rr-totix~~~riox~ for extending, 136 reasons for not extending, 148-155, 168-172, IYS(n27) L~festages, 57, h9-76, 158, 1011. 164, 185tn32) Llpo\omes, 92 Lxvcr Gil~~lre, I30 Lrv~~rg-orgax~ dox~attonr,56 McMah~n.Jeff,3 Mscrt~phager,153,154 Major depressiol~,59 MsIaria, 211, 93, 1-52 Marteau, TI-reresa, 13, I 4,75 Msstecto~~~y, 181(nX). Sf*e aho Cancer(\), breast cancer Marer~dlistn,23 Mate selection, I 10 Maxirntx~theory, 1Hfi(x14X) Msxirnum rule, 77 Meanr/ends, 5, l I X, 1l 9, 126-1 28, 134, lVO(nr>),1(32(1121) Med~cnltrcatmtnt, "7-"7,7") 83, I 60. See IEIAR Health care Mehlman, M'~st,vcU,I Oit Megers-Heghoer, Hanne, 1X I (nX) Memory 21,23,31,253, X") 95,96,163, I 67 and antictpadon, 16% 17if, 172 and evolutionary biology- 1hX-l69 and new projects, 165, 168, 170 short-/long-term, 16") 170 Mental dxsurcters, 13, 30, 52,98 and gelre therapy (335--(27,W-Yl rrlental wt'trdation, 30, 54, 68 See illso Do\%311ryndrsnte; Sch~zo phrenia Mex~calsldtes. 21.22,2g-30, 33, 81, 9(J, 96, (37, "21, 105, 129, 164 of future self, 16% mental life a13 r~ioralrtatus, h7-68
potential vs. capdcrty for, 24,29, 6 l, 179Cn32) responstbxliri): for, 108 Scc also Gc)rtsciausner$:Psychotog~cal connectedness/continu~ty:ettrdcr Ealvlronn-tentdt factor^ Met~plysxcalissues, 2,3, 10, 25, 118, 124 and beneFlt/fimnt rcsues, 36 and causal cc)ntrol, 49-5if ofpersona1 ~dentie.)i, 94. Sec rilsn Identity Metk~uselab'sParadox, 167 Methylation, 14 M~~carr~ages, 6'7 Micochondxra, 93--94, 129 Maral issues, 2,3,4-5,") 110,21, 80-XI, 118. 130, 153, 173 and s t u t o ~ ~ o i108-1 ~ ~ y , 119 existel~ceas rr-torally neutral, 69, 74 and genetic enfiancei~ient,109 morality vs. ethrcs, 4 ~llc>ral atatus of eimbryc.)r,67-68 and p~"frence.svs. need&,7'7, I 00, 156 and Probdbrlisric Discount Rare, 156 and relation c?rfgenes and persondl rdentiey, 34-38 rei3uireimerlt vs. perr~Gss~on tc:, prevent existexlce, 74,75, Sec idso C9131igation , tc:, preveglt existel-tce of people and reverity of cclndition vs. 1lu1lil3ers at&cted, 38, 51, X4 See also Renctitihann irsucs; Fairxlcs.;; Mtamiends; ObIigatxon; Responsthllity;Worse-off prioriv prinncli>le M~)rt~~fif)r, 135, 138, 148, 1SO,173 Muutions, 11, 1" 113, 14,20,21,31,33, 36,5Cf, -51, -52, 55, 56, 57*59, 6'7, 71-72, (91,93, 10") 111, 119 and cell maintenance. and repair, 136 and clonmg, 123, 124, 125, 1221, 135 and extendirig hfe spans, 148, 151, 156, 158, 173 in po~lt-reproductivei>eriod, 138, 249-150, 153 'trltI rexual/~sexualreproduction, 123, 124
Ndgel, Thont~s,83, 178Cx128) Narveson, Jan, lX2tn13) Nash, Ada111, 128 National Nioethic.; Advisory C:omrt?issic>n, 11'7,1128 N ~ ~ I o xcenter I ~ I Il>r Health Research. 1X N ~ ~ I o xCenter I ~ I for Hti~ndr~ Cel~ollte RePlertrch, 1 N ~ ~ I o xH~XII~JXI I ~ I Cellollte Research Irzstitute, 12 Natrondl X~~scitutes c?rfElc'1lt11, 1 ?-dativeAlnericdrts, 1'9 Natural selectrun, 10-1 I. 1X,3X, I 52 and diet, 19 and extendrng hfe spans, 148, 149, I53 and i~~~rrlutrc sysrellt, 15 and rerlercence, 138 See illso Ettoltrtion~rybiology Nesse, Kandotph, 3, 14, 1") 1152, 2-53, 155 Ne~rrutram~rutters, 16,28,2"3 3 35,33, Y O Obhgdtion, 34, 49,64, 112, 157 absence of, 53, 55 to brrng people into cxstence,62, 74 and c h ~ l d r e opg~ortuniey ~~i 59 and ciegree of risk, 56 eptstexl-ttc aspects of 52 tc:, tirture ~>eopte,135, 137, 148 and gcr~~i-lme. rnanlptrlatxon, 93 tc:, 1t1fi3rm chlldrerl of risk, 50, 53, 55, SC,,SK kgal. 58--59, 95 to pjuc.L-ent exatence of people, 2,5(1-.51, 61, 63, h5,hh--h9,71,73,74,75--76, 82, 84, 8.5, X9 and severiv of disease, 57-5X,68, 84, 101, 102 to test/be tested, 50, 51,52, 53,55, 56, -58 O~xuchmctranscarbalrlyfdse dcficzency (C>TC),92 Ooplasrr~~c transplantation, 9-3-94 Og311ortuniry,59,81, 82,87,97,9X, 99, 100, 1114, 106, 156, 1h4, 1821n12) Oxg)f Social class, 1lC) Social constructs, 17
Soctal Secsrriq and Med~care,159, 1h0 Socldl %tatus,10,T Solrclr, Davar, 191(nX) Sortals, pllase VL tuba~nce,25 Stem ccfls. See Elnbryos, e~iibryon~c \tern cell% Stmke, %,9'7,135, I 39 Suicide, hr 1 asvrted tulclde, 71 Sw~fi, Jonathan, 164-165 Synapset, 28.29.33 Synga~rl).; 26-27 T ~ x ~ t r o100, n , 159, I72 Tay-SdcX~sdi~ease,37,5C1,53--54, hh,7h, 111,115, I23 nuntbers ~Btcted,I01 T-cells, 1.5, 33, 153, 1.54 Teenage pregnancy, 1IX Telo~lleres/telo~l~erase? 123, 124, 136, 138, 139,146, 147, 155 Th'tlamur, 2 1 Thalassernia, 92,105 TNE See Tt~ra-tornecrczsis factor Tooley?Michdel, 17")n132) Tort of wrczngful hfe, 58 Toxic-w'arte d u ~ l ~ plsX, Tt~berculost%. 150 Turnor necrc>sii;factor (TNF), 139, 146, 153-154 Tkvirts, 132, 127 Typl-to~dfever, I52 Ulcers, I54 tralger, l'ecer, 178Cx12X) United States breast caxlcer 111, 18-1 C) elderly in, 158-159 C;r-orr; 13ornesac Product, 10I House of Kel.rrerentdtivec, 117-1 1X Supreme Court, 129 treerir~eenvlrunn-tent, 28,h0, 13 1 tlaccines. Sec Intt1tutrrz~croxa/t~acc11:~es V~scularendotllelial growth factor (VECF), 92
VEGF. See Vascular endorheli~l,growth tltctor k n t c r , Crag, 12, l"aA(n6) Viral vectors. See uilder Gene therapy Wakayat~ta,T,,12U, Il-)I(nH> WaIcers, Lercy, lif2-103, I XH(n26) Warson, Juries, 12 WeU-being. Scc Quahty of life
WikEcr, Daniel, 3--4 WiUiar~~$, Bernard, 112 W a ~ m s(I;curgt;e , C., 3,4, 14, 10,152, 153, 1.55 Wilmut, Xan, I 17, 119, 120, 1"dljnX) Wc>rse-otTpriorif?rprinc~ple,Xi--X4,9X--99, 101, 102, I 5?-1,%K,173, IXfi(lr48) Zygotes, X?--2?,28,32,17Vjn32)
