Hume and Thick Connexions Simon Blackburn Philosophy and Phenomenological Research, Vol. 50, Supplement. (Autumn, 1990), pp. 237-250. Stable URL: http://links.jstor.org/sici?sici=0031-8205%28199023%2950%3C237%3AHATC%3E2.0.CO%3B2-I Philosophy and Phenomenological Research is currently published by International Phenomenological Society.
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Philosophy and Phenomenological Research Vol. L , Supplement, Fall 1990
Hume and Thick Connexions S I M O N BLACKBURN
Pembroke College
1. Two Approaches Recently there has been a pronounced shift in the interpretation of Hume on causation. The previous weight of opinion took him to be a Positivist, but the new view is that he is a Sceptical Realist.' I hold no brief for the Positivist view. But I believe it needs replacing by something slightly different, and that at best it shows an error of taste to make Sceptical Realism a fundamental factor in the interpretation of Hume. Let us call any concept of one event producing another, or being necessarily a cause or consequence of another, but which involves something beyond the concept of regular succession a "thick" notion of the dependence of one event on another. Then on the Positivist account, Hume believes that no thick notion is intelligible. O n the Positivist view there is very little that we can ever understand and mean by a causal connexion between events. All we can understand and properly mean by talk of causation is that events fall into certain regular patterns, and the Positivist interpretation is that Hume offered this as a reductive definition of causation. This is the famous regularity theory, summed up in the 'philosophical' definition of 'an object, followed by another, and where all the objects similar to the first are followed by objects similar to the second'.' The sceptical realist view denies that Hume offered any such reduction or analysis of the notion of causation. It takes seriously the many passages in which Hume appears to allow that we are talking of some thick notion of dependence of one event on another, going beyond regular succession. It takes it that Hume acknowledges that there is some such thick relation, even if it will be one about whose nature and extent we are doomed to
I have in mind Edward Craig, The Mind of God and the Works of Man (Oxford: Oxford University Press, 1987); Galen Strawson, The Secret Connexion (Oxford: Oxford University Press, 1989), and John Wright, The Sceptical Realism of David Hume (Manchester: Manchester University Press, 1983). Enquiry Concerning Human Understanding, ed. Selby Bigge, Section VII pt. 2 , p. 76.
H U M E A N D THICK C O N N E X I O N S 2 3 7
ignorance. Hence, in John Wright's phrase, Sceptical Realism. At first sight the difference between Positivism and Sceptical Realism is reasonably clear, and it is clear too that if these are the two options Hume is better seen as tending towards the second. But, as proponents of the Sceptical Realist interpretation realize, there is one big problem. This arises from Hume's theory of meaning. Sceptical realism seems to demand that we know what it would be for one event to depend thickly upon another, even if we are ignorant of the nature of this relation; Hume seems to demand that we have no impression, and hence no idea of any such dependence. The problem here is a problem for anybody, and can be focussed on a contradiction, to which Hume seems to be committed: (I)
(2)
(3)
We have no ideas except those that are preceded by suitably related impressions. There are no impressions that are suitably related to the idea of a thick necessary connexion between distinct events. We have an idea of a thick necessary connexion between distinct events.
The 'suitable relation' spoken of includes direct copying, in the case of simple ideas, and whatever is covered by 'compounding' in the case of complex ideas that are compounded out of simple ones. The Positivist interpretation takes Hume to be claiming that when we talk of causation we only mean something that strips out the thick element of necessity, and substitutes regular contiguous succession. So (3) is false. The difficulty is that Hume denies this: Shall we then rest contented with these two relations of contiguity and succession, as affording a compleat idea of causation? By n o means. An object may be contiguous and prior to another, without beingconsider'd as its cause. There is a NECESSARY CONNEXION to be taken into consideration; and that relation is of much greater importance, than any of the other two above-mentioned.'
The central problem in interpreting Hume is coping with the contradiction. The Sceptical Realist strategy is to downplay the importance of the theory of understanding, so that even if Hume officially said (z), it played a negligible part in his view of causation.
Treatise of Human Nature, edited by Selby Bigge (Oxford: Oxford University Press, 1888), P. 77.
2. A Doubtful Distinction How then does the Sceptical Realist deal with the problem of meaning? Edward Craig and Galen Strawson draw attention to a distinction that occurs in Hume's writing^.^ When the theory of ideas threatens our idea of external existence or 'body', it is said that Hume invokes a distinction between what we can 'suppose' and what we can 'conceive', the idea being that we can coherently suppose that there are things of some sort (external objects) even when strictly we have no idea of what it is that we are supposing. Another way of putting it is that we can have a 'relative' idea of things whose 'specific' difference from other things we cannot comprehend. We could say that we have no representative idea of what we talk about, but a relative or relational idea, locating it by its role. We would talk of a 'something-we-know-not-what' that does something or bears some relation to an aspect of the world of which we do have an idea. This distinction solves the contradiction by distinguishing between the terminology of ( 2 )and (3).Hume thinks we have no representative idea of causation: we have no impression of it, and in some important sense it remains incomprehensible, and we cannot represent to ourselves what it is. What we do have however is a relational idea of it - it is whatever it is that issues in regular successions of events, or upon which such patterns depend, or whatever forces such regularities. The negative side is given in (2), but the positive side in (3). The texts give no direct support to this interpretation of Hume. While he uses both a 'relative' vs. 'specific' distinction and the possibility of 'supposing' what we cannot 'conceive', he uses them very sparingly indeed. In fact he never uses either, nor mentions either in connexion with causation. He never uses or mentions either in the Enquiry or in the Dialogues in any context at all. This alone makes them an unlikely candidates for a central r61e in understanding his mature p h i l ~ s o p h y .But ~ worse, there are warning signs to be noticed when they occur in the Treatise. There are four occurrences: on pp. 67-68, p. 188 referring back to it, p. 218, and p. 241. In none of these cases is Hume actually contrasting a specific versus a relative idea of any one property or relation, enjoining us that we can know a property or object by its relations even if we cannot know it by some stricter standard derived from the theory of ideas. On the contrary, in each context it is the impossibility of conceiving a 'specific difference' between external objects and perceptions that is the focus of
'
Edward Craig, The Mind of God and the Works of Man (Oxford: Oxford University Press, r 9 8 7 ) , p. 1 2 4 . Galen Strawson, op. cit., chapter 12. It is particularly odd that Strawson relies upon them, since he conceives of the Enquiry as embodying Hume's official theory of causation.
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239
attention. 'Specific' qualifies the properties supposedly differentiating external objects from ideas, and of these specific qualities we know and understand nothing by any standard at all. Here are the two major passages with enough surrounding context to matter: Now since nothing is ever present to the mind but perceptions, and since all ideas are deriv'd from something antecedently present to the mind; it follows, that 'tis impossible for us so much as to conceive or form an idea of any thing specifically different from ideas and impressions. Let us fix our attention out of ourselves as much as possible: Let us chace our imagination to the heavens, o r to the utmost limits of the universe; we never really advance a step beyond ourselves, nor can conceive any kind of existence, but those perceptions, which have appear'd in that narrow compass. This is the universe of the imagination, nor have we any idea but what is there produc'd. The farthest we can go towards a conception of external objects, when suppos'd specifically different from our perceptions, is to form a relative idea of them, without pretending to comprehend the related objects. Generally speaking we do not suppose them specifically different; but only attribute to them different relations, connexions and durations. But of this more fully hereafter. (p. 67-68) Philosophers deny our resembling perceptions to be identically the same, and uninterrupted; and yet have so great a propensity to believe them such, that they arbitrarily invent a new set of perceptions, to which they attribute these qualities. I say, a new set of perceptions: For we may well suppose in general, but 'tis impossible for us distinctly to conceive, objects to be in their nature any thing but exactly the same with perceptions. What then can we look for from this confusion of groundless and extraordinary opinions but error and falsehood? And how can we justify to ourselves any belief we repose in them? (p. 218)
It requires some daring to take these passages as a model for sceptical realism. Hume is far - about as far as can be - from saying that we actually possess a going idea of the external world, which allows us to understand, by some weak standard, what the externality is that we do not know about. Each of the two passages gives the strongest contrary impression. The first affirms idealism ('. . .we never really advance a step beyond ourselves'). The second introduces the 'supposes versus conceives' distinction only while he simultaneously dismisses its effect out of hand. Its dismissal justifies Hume in describing his Philosophers (the culture whose spokesman is Locke) as actually inventing new perceptions, rather than inventing new things different from perceptions. This is the very opposite of the view a Sceptical Realist Hume should take. He should take seriously the view that a Lockean succeeds in introducing a (relative) notion of an external object as something that has various relations to our perceptions, and go on to worry how much we know about them. Hume does not: he simply dismisses the idea that we have a set of determinate, intelligible, propositions about which, unfortunately, we shall never know the truth. We are in the Humean domain of a 'confusion of groundless and extraordinary opinion' where our only hope is to abandon reason
altogether. But we shall shortly find that the theory of ideas makes this inevitable in any case.
3. Another Distinction Before proceeding it is necessary to have in mind two things that might be asked of 'thick' causation. When we think of a causally connected pair of events, such as the impact of the first billiard ball causing the motion of the second, we want there to be a further fact than (mere) regular succession. We want there to be a dependency or connexion, a fact making it so that when the first happens the second must happen. Call this the desire for a causal nexus. But now suppose we shift our gaze to the whole ongoing course of nature. Again, we may want there to be a further fact than mere regular succession. We feel that the ongoing pattern would be too much of a coincidence unless there is something in virtue of which the world has had and is going to go on having the order that it does. We want there to be some secret spring or principle, some ultimate cause, "on which the regular course and succession of objects totally depends."6 This is whatever it is that ensures the continuation of the natural order, that dispels the inductive vertigo that arises when we think how natural it might be, how probable even, that the constrained and delicate pattern of events might fall apart. Call the desire for this further fact the desire for a Straightjacket on the possible course of nature: something whose existence at one time guarantees constancies at any later time.' A fact alleviating this vertigo has to be a very peculiar fact, for the following reason. It has to be something whose own continued efficacy through time is subject to no possibility of change or chance of failure. For otherwise the fact that it keeps on as it does would itself be a case of coincidence or fluke, another contingency crying out for explanation and engendering inductive vertigo. Some think they can point us towards a fact with this potency. Some draw comfort from God's sustaining will, as if anything understood on the analogy of our own mental states could be timeproof! Armstrong believes that a kind of necessary, timeless, gridlock of universals will do.' Galen Strawson takes comfort in fundamental forces constitutive of the nature of matter.9
Enquiry, p. 5 5 .
' At least. It may be that its existence at one time should entail its existence at any previous
'
time as well. But one way of gesturing at what is wanted is to imagine God creating it by some kind of fiat or act of lawgiving, whose writ would run into the future. What is a Law of Nature (Cambridge: Cambridge University Press, 1983), p. 88 ff.
It is easy to confuse the desire for a nexus, case by case, with the desire for the Straightjacket. But Hume (sometimes - but see below) is clear that they are different. They are different because whatever the nexus between two events is at one time, it is the kind of thing that can in principle change, so that at a different time events of the same kind may bear a different connexion. Thus suppose we grant ourselves the right to think in terms of a thick connexion between one event and another: a power or force whereby an event of the first kind brings about events of the second. Nevertheless there is no contradiction in supposing that the powers and forces with which events are endowed at one time cease at another, nor in supposing that any secret nature of bodies upon which those powers and forces depend itself changes, bringing their change in its wake. Hume emphasises this point in both the Enquiry and the Treatise.'" It is his reason for denying that the problem of induction can be solved by appeal to the powers and forces of bodies. But it is equally a reason for separating the question of a nexus from that of the Straightjacket. Nexuses by themselves do not provide a Straightjacket. The ongoing regularity and constancy even of thick nexus between one kind of event and another is just as much a brute contingent regularity as the bare regular concatenation of events." In each case we have something that can engender the inductive vertigo, or whose continuation through time might be thought to demand some kind of "ground" or ultimate cause or Straightjacket. The difference between a nexus, holding on some particular occasions, and a Straightjacket guaranteeing the continuation of a pattern of connexions is easy to confuse. This is because of a lurking epistemological difficulty. Suppose one thinks that a particular nexus can be known for what it is, for instance by some observation whose content is more than the mere succession of events. One might report that by claiming to have seen that the one event had to happen, given the other. But if you see a 'must' in one pair of events, would you not thereby see that it will hold for every pair of some kind that the original pair enables you to identify? How could you see it without seeing something with general implications, and ones that are immune to temporal change? In other words, you will take yourself to have seen a timeproof connexion: one that Straightjackets how things could ever fall out. To put it the other way round, if things were not to fall out as expected, the original claim to have seen that the 10
Treatise, pp. 90-91, and Enquiry, p. 37. " One might seek to avoid this by the verbal manoeuvre of identifying kinds of events by their causal powers, in which case it will follow that events of the same kind will bear the same causal connexions. But as Hume in effect points out, inductive vertigo then transfers itself to the contingent question of whether future events with the same sensory appearance will turn out to be of the same kind.
one event had to follow the other is refuted. This in turn makes it hard to see how a particular nexus could be an object of observation. Observation extends only to limited periods of space and time: how could we have within our view something that essentially casts its net over the whole of space and time? This problem probably explains one puzzling feature of Hume's procedure. He repeatedly affirms that someone who has a full apprehension of a causal connexion would be in a position to make an a priori claim about the way events will fall out: what kind of event will be caused by another. It is because we cannot have this timeproof knowledge that we do not apprehend the causal connexion, for instance in the exercise of our own will." The argument seems initially to be, as Craig describes it, a muddle, since there is no evident reason why someone apprehending a nexus on one occasion should thereby know that the same nexus will obtain on another - the very point Hume himself emphasizes when arguing that powers and forces will not solve the problem of induction." I suspect that Hume sees that nothing would really count as apprehension of a particular 'must' unless it carried with it implications of uniformity for the general case. It is to be (per impossibile) a particular apprehension, but one with the consequences of apprehending a Straightjacket. Someone apprehending a Straightjacket for what it is will as a consequence know its immunity to time and chance: he will know the timeless must that it guarantees. He will be apprehending the impossibility that events should ever transpire otherwise. He has therefore a piece of knowledge that, although it took an empirical starting point in the apprehension of an individual thick necessary connexion, can be seen a priori to have implications for allother places and times. And it is this that Hume treats as his target, even when the issue ought to be the apparently lesser one of the particular nexus. There may be some room for manoeuvre over the lesser claim to have apprehended a particular, but not necessarily timeproof, thick connexion. One might try allowing the particular apprehension not to carry any implications for what might be present on other occa~ions.'~ T he difficulty will be that an apprehension of a mutable thick connexion does not give us quite what we want from knowledge of causation. That knowledge has to have a consequence: the subject possessing it must be prepared to foretell the one event on the appearance of the other. It is not
11
'' I4
Enquiry, Section 7 , passim. Hume, Treatise, p. 91,Craig, op. cit., p. 97. Anscornbe, G. E. M . '
