Review of Heller

Review: [Untitled] Reviewed Work(s): The Ontology of Physical Objects: Four-Dimensional Hunks of Matter by Mark Heller Dean W. Zimmerman Philosophy and Phenomenological Research, Vol. 53, No. 1. (Mar., 1993), pp. 220-224. Stable URL: http://links.jstor.org/sici?sici=0031-8205%28199303%2953%3A1%3C220%3ATOOPOF%3E2.0.CO%3B2-B Philosophy and Phenomenological Research is currently published by International Phenomenological Society.

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gated skepticism cannot be defended by any deeper form of argumentation. Unlike Hume, however. he thinks that it is possible to look this result in the eye without a consequent loss of a feeling of rational autonomy. In this way Hookway axrives at a compatibilist soft skepticism parallel to Hurne's compatibilist soft determinism. ROBERT J. FOGELIN

D a r t m o ~ hCollege

The Ontology of Physical ObJects: Four-Dlmenslonal Hunks of Matter. MARK HELLER. Cambridge: Cambridge University Press. 1990. 9. xiv. 162. Mark Heller's The Ontology of Physical Objects is. as far as I know. the only book-length defense and exposition of "four-dimensionalism" or "the metaphysics of temporal parts" (MTP). MTP is the view that just as extended things fill space by having different parts in different places. persisting things last through time by having different parts at different times. Although MTP is quite popular, most proponents have given only brief arguments in its favor and worried little about its broader ramifications.' Heller's book fills an important gap in the literature on this subject, and should be of interest to metaphysicians of every stripe. Heller argues that the metaphysics of physical objects which he calls our "standard ontology" is false. By "the standard ontology" he means a metaphysics according to which tables, trees. mountains. people. and the like are three-dimensional objects which persist whole and entire from one moment to the next (i.e.. without having a distinct temporal part for each instant or temporal stretch during which they exist) and which could have had shapes and spatiotemporal careers other than those they actually have. The "replacement ontology" he advocates is a version of MTP which identifies physical objects with "four-dimensional hunks of matter" having their actual spatiotemporal configurations and careers essentially. Although he thinks his arguments call for the replacement of the "standard" ontology we already have, he admits that some philosophers will insist that he could only succeed in showing that we are already ontologically committed to four-dimensional hunks of the sort he describes-i.e., that the truth conditions of our usual claims about physical objects involve such hunks. His primary goal, however, is simply to show that MTP is true. He suspects that its truth implies the falsity of all our commonsense assumptions about physical objects, but he is not interested in fighting for this claim (pp. ix and 148-51).

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For influential presentations of MTP, see: C. D. Broad, Scientijc Thought, pp. 53-55; Bertrand Russell. "The Ultimate Constituents of Matter." in his Mysticism and Logic (Garden City. New York: Doubleday and Co.. 1957). esp. pp. 123-24; W. V. 0.Quine. Word and Object (Cambridge. Massachusetts: M.I.T. Press. 1960). p. 171; Nelson Goodman. The Structure of Appearance. 2nd ed. (Indanapolis: Bobbs-Memll Co.. Inc.. 1966). pp. 127-30; Richard Taylor. Metaphysics (Englewood Cliffs. New Jersey: Prentice-Hall. Inc., 1963), pp. 70-71; Richard Canwright. "Scattered Objects." reprinted in his Philosophical Essays (Cambridge. Massachusetts: MIT Press. 1987). pp. 171-86; and David Lewis, On the Plurality of Worlds (Oxford: Basil Blackwell, 1986). pp. 202-3.

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The argument of the book moves along two fronts: There is a "destructive project", whose goal is the demolition of the standard ontology; and a "cunstructive project", which consists of positive arguments for his version of MTP. The two are closely interrelated, since the arguments against the standard ontology place severe constraints upon any replacement proposal such as MTP;and a radical view such as Heller's becomes more palatable once metaphysical theories that seem closer to common sense (such as the standard ontology) are hled out. The destructive project takes inspiration from a series of papers by Peter Unger.2 Unger tried to show that conceptual vagueness produces Sorites paradoxes which imply the impossibility of +there being such ordinary objects as stones. tables, and people. Heller's own Sorites argument is a reductio ad absurdurn that turn upon the apparent vagueness of persistence conditions for ordinary objects: For any term "S" that connotes an ordinary kind of physical object (e.g., "table," "mountain," "human being"), there is a series of (actual or merely possible) objects varying slightly from one another which is such that (i) "S" is definitely applicable to early members in the series. (ii) "S" is definitely not applicable to the final members, but (iii) there is no precise point in the series at which "S" becomes inapplicable. The "standard ontology" is committed to the existence of three-dimensional, persisting objects which belong essentielly to the categories named by each such term. If this ontology were correct, then the vagueness surrounding our physical object categories would have to reside either in our hazy use of these terms to refer to objects which in fact have precise persistence conditions, or else in the actual vagueness of physical objects. But there cannot be vague objects, so the standard ontology implies precise persistence conditions-knowable or unknowable-for its objects. Since no additional information accessible to us is sufficient to make such conditions known, they must be unknowable for us. But they cannot be unknowable either. If it were impossible for us to know what changes are sufficient to destroy a thing, then we would not know what changes it is capable of surviving-and the standard ontology insists that tables and chairs do survive certain minor changes. Thus the standard ontology must be false. About one-fourth of the book (chap. 3) is devoted to supporting the various premises of the argument just sketched. Of particular interest is the discussion of the relevance of multivalued logics and supervaluationism in the "vague objects" debate. Heller shows that, unless one is prepared to recognize a sort of halfwayhouse between existing and not-existing. objects with truly vague persistence conditions are imp~ssible.~ Heller's arguments against vague objects and the rest of his assault upon the standard ontology seem to me to be important and largely successful. Since the rejection of any element of the standard ontology does seem to represent a departure from our commonsense assumptions about physical objects, he succeeds in showCf. Peter Unger, "There Are No Ordinary Things," Synthese, Vol. 41 (1979), pp. 11754; "I Do Not Exist," Perception and Identity, ed. by G. F. McDonald (Ithaca: Comell University Press, 1979), pp. 177-222; "Why There Are No People," Midwest Studies in Philosophy, IV (1979), pp. 177-222; and "The Problem of the Many," Midwest Studies in Philosophy, V (1980), pp. 411-67. The pmblems Heller raises for vague objects constitute a serious objection to Peter van Inwagen's attempt to countenance vague persistence conditions for composite objects. Cf. van Inwagen, Material Beings (Ithaca: Comell University Press, 1990). 39 17-19.

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ing that, whatever the truth is about physical objects, it is bound to be a somewhat odd and unintuitive truth. His constructive project consists of an argument for the particular oddities of MTP. Arguments for MTP have been mounted upon several bases: pervasive analogies between space and time: the "fusion" of space and time effected by relativityg5 problems of intrinsic change,6 and problems of mereological change. Heller's argument for MTP is of the final sort, and its general outline is relatively familiar.7 If one holds that objects are three-dimensional things persisting whole and entire through time, then one must accept one of the following "unpleasant alternatives": Either (i) there are no undetached parts (e.g.. my hand does not exist unless it is severed), (ii) mereological essentialism is true (i.e.. no object can undergo the gain or loss of a part). (iii) there can be two precisely similar entities in the same place at the same time, or (iv) identity is not transitive. For suppose all four were false together. Then, by the denial of (i), my hand (to take one plausible example) exists now, as does my "hand-complement'' (the remainder of my body, excluding my hand). Of course neither are identical with my whole body, of which they are proper parts. Since this case constitues one of our reasons for denying (ii), we must assume that I can continue to exist even if my hand is amputated. But after amputation, the three-dimensional, persisting "hand-complement" and I seem to suddenly occupy the same place at the same time, which is impossible by the denial of (iii); so they must have become identical, which is impossible by the denial of (iv). According to Heller, instead of giving up and admitting that one of (i)-(iv) is .true, we should simply deny the three-dimensionalism presupposed in the argument. The fact that the four-diiensionalist can reject all four "unpleasant alternatives" is the only reason Heller gives for adopting MTP (pp. 2-4). In developing his version of MTP. Heller points out that one can hold MTP without treating persisting objects as "built up out of instantaneous objects" (p. 6). Perhaps persisting objects have no instantaneous parts, even though they are infinitely divisible along their temporal dimension into ever smaller extended slices. In any case, they need not be regarded as sets or sums composed out of more fundamental instantaneous objects. Instead, persisting objects can be regarded by the four-demensionalist as simply "hunks" of material stuff spread throughout a region of space-time. This move seems a wise one. Identifyiiig objects with sets or sums of temporal partsrsuggests that they could not have failed to have the parts they in fact have, from which conclusion strange, fatalistic results would seem to follow. For example, on the assumption that my body is a set or sum of temporal parts, it looks like it would be impossible for me to die before or after the date of my actual death.s One might think that a version of MTP like Heller's, which identifies per-

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Cf. Taylor, Metaphysics, pp. 70-71. Cf. Milic Capek, The Philosophical Impact of Contemporary Physics (Princeton, New Jersey: D. Van Nostrand. 1961). chapter 15. Lewis, On the Plurality of Worlds. pp. 202-3. Cf. Eli Hirsch, The Concept of Identity (New Yolk: Oxford University Press, 1982). pp. 57-61: Richard Cartwright, "Scattered Objects"; Peter van Inwagen, "The Doctrine of Arbitrary Undetached Parts," Pacific Philosophical Quarterly. Vol. 62 (1981), pp. 123-37; and Judith Jarvis Thomson. "Parthood and Identity Across Time," Journal of Philosophy, Vol. 80 (1983), pp. 201-20. Cf. van Inwagen, "Four-Dimensional Objects," Nods, Vol. 24 (1990), pp. 245-55.

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sisting things with four-dimensional "hunks" of stuff, could avoid this conclusion. If "hunks" are sufficiently unlike sums or sets of stages, perhaps they could differ in shape and spatiotemporal location "across possible worlds." Heller argues, however, that his four-dimensional hunks are just as "modally inductile" as the sets or sums of stages utilized in other versions of MTP.9 On his view, too. objects have their spatiotemporal shapes and locations essentially. I have reservations about some of his arguments for this conclusion. For instance, his reasons for thinking that a thing's location in,space-time is essential to it depend upon the rejection of "brute identity differences" between qualitatively similar possible worlds. Many philosophers will be unconvinced, however, being quite prepared to recognize such haecceitistic differences.'' Nonetheless, other considerations he raises do suggest that the modal properties open to four-dimensional objects will not match up nicely with the modal properties we tend to ascribe to enduring objects. In particular, it appears that four-dimensional hunks have their spatiotemporal shapes essentially. And this is sufficient to raise a serious dilemma for Heller's constructive project. As noted above, the argument given for MTP depends upon the "unpleasantness" of four alternatives, three of which were, in essence, mereological essentialism (the thesis that no object can undergo a change in its parts), the denial of the doctrine of arbitrary undetached parts (roughly, the doctrine that an extended object has a distinct part for every connected, three-dimensional region within the space it fills)." and the admission that two distinct physical objects can be in the same place at the same time. But, clearly. if MTP turns out to be just as "unpleasant" as any one of these alternatives, then Heller's argument for fourdimensionalism evaporates. How unpleasant does MTP become? If Heller is right, it becomes a kind of fourdimensional mereological essentialism. Objects have their four-dimensional spatiotemporal shapes essentially. Thus the movements a thing makes, for example. are ones that it could not have failed to make. And. on Heller's (provisional) assumption that all of an object's intrinsic properties supervene on the spatiotemporal configurations of its parts (p. 6). every intrinsic property of a thing is essential to it. Whether such Leibnizianism is more or less plausible than mereological essentialism or the denial of the doctrine of arbitrary undetached parts is a nice question. Heller is prepared to admit that MTP may face rival metaphysical theories which are "equally good but incompatible" (p. 51, n. 15). But suppose MTP and mereological essentialism, say, are running neck and neck. Then the stiff essentialism of his version of MTP seriously undermines his mereological argument for four-dimensionalism in a further respect. The argurn-int depends upon our conviction that some things do indeed survive certain changes in their parts; the denial of this was the "unpleasantness" associated with mereological essentialism. But consider the reasons one might have for thinking that some things survive changes of parts. Are these reasons distinct from those that ground our convic-

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Similar arguments may be found in van Inwagen, "Four-Dimensional Objects," and W. R. Caner. "On Contingent Identity and Temporal Worms," Philosophical Studies. Vol. 41 (1982), pp. 213-30. Cf. Robert M. Adams, "Primitive Thisness and Primitive Identity," JournuI of Philosophy, Vol. 76 (1979), pp. 5-26. Cf. Peter van Inwagen. "The Doctrine of Arbitrary Undetached Parts."

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tions that things could survive changes which they do not actually undergo? Suppose that, while Heller and I are talking. I observe that one hair falls from his head. He then uses this as an example that shows the falsehood of mereological essentialism, since he obviously survived the loss of a single hair. But why would I think that he did survive the loss of a hair then, if I did not also believe that I could have survived the loss of a similar hair at that moment, too? But, by his lights, I could not have survived the loss of a hair (since I did not lose one then). If my knowledge that a thing did survive a certain change is based upon or otherwise presupposes my knowledge that things of that sort can survive such changes, then Heller's argument is weakened in a curious way. Upon accepting its conclusion, I immediately lose my reason for believing a crucial premise. Does such subtle "self-referential incoherence" show that Heller should cease believing his version of MTP? Perhaps not.12 However, the following principle seems to me to be a good one: When faced with a choice between two incompatible theories which have roughly the same amount of evidence in their favor, if accepting one of them would entail the loss of your evidence for that theory. while accepting the other one would not result in a corresponding loss with respect to its evidence, then do not accept the former one. Someone not antecedently committed to four-dimensionalism should not, then, find Heller's argument persuasive. A number of other important matters come up in the course of discussion. There are lengthy explorations of the semantic relationships which would have to hold between our ordinary statements about physical objects, and the four-dimensional entities which make our claims at least "appropriate", if not literally true. The usefulness of a counterpart-theoretic semantics for making sense of ascriptions of modal properties to physical objects is also briefly discussed. Heller's arguments are usually convincing and always interesting. The book's sometimes complicated dialectical structure remains relatively transparent throughout. I recommend The Ontology of Physical Objects to anyone interested in the metaphysics of concrete individuals. and anyone who wants to know just how hard it is to be a friend of temporal parts. DEAN W.ZIMMERMAN

Universily of Notre Dame Baffling Phenom'ena and Other Studies in the Philosophy of Knowledge and Valuation. NICHOLAS RESCHER. Savage. Maryland: Rowman & Littlefield. 1991. Pp. ix. 223. Strictly according to the rules, the first two words of the title of this book should be in quotation marks, for the reference is to the name of the first essay in this collection. Perhaps an editor, anticipating problems of electronic cataloging and retrieval, red-penciled them. Three of the twelve essays (nos. 1, 3, and 11) have appeared earlier and have been revised for publication in this volume. The others are newly published. The book is dedicated to Ernest Sosa, editor of this Journal. l2

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Cf. George Mavrodes. "Self-Referential Incoherence," American Philosophical Quarterly, Vol. 22 (1985), pp. 65-72.

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