The principal claim of Part 2 is that the standard account of Hume on causation is incorrect even as regards the Treatise. A key part of the argument for this claim (in 15.3) doesn’t appeal to Hume’s use of referring expressions that apparently refer to Causation. It concentrates instead on quotations that appear to support the standard view, in order to argue that they don’t really do so. Hume does nevertheless make a considerable number of apparently straightforward references to Causation in the Treatise, and I will now briefly consider some of them, here and in 15.2, without expecting them to carry the main weight of the argument.
At the beginning of 1.3 Hume speaks without irony, and in an apparently straightforwardly referring way, of
(1) [REF] the power, by which one object produces another,
commenting that it is [EP]‘never discoverable merely from [the] idea’ of the objects in question (69/1.3.1.1)
It may be said that it would be unwise to rest much on this quotation. A better example occurs in 1.3.6, where he says that when we are faced with two objects (i.e. two types of occurrence) that have always been conjoined,
(2) we [EP] cannot penetrate into [REF] the reason of the conjunction (93/1.3.6.15).
There is, certainly, [NI] a reason for the regular conjunction, but we cannot know anything about its intrinsic nature. For all we can ever detect in the objects is precedency, contiguity, and constant conjunction.
It is not only when we think of reality in the ordinary realist way that we see that this is so. It is equally so if we think of reality, so far as it exists beyond our perceptions and their content, in Berkeley’s way. This is important to Hume. Indeed his belief that we cannot even rule out Berkeley’s theory of the true nature of reality (see e.g. 84/1.3.5.2) is perhaps his second main reason (after his belief that Causation has the AP property, discussed in 11) for being so sure that we can never know anything of the nature of Causation or power as it is in reality.
At the heart of his discussion of our idea of causation in 1.3.14, Hume remarks that almost all philosophers agree that
(3) [REF] the ultimate force and efficacy of nature is [EP] perfectly unknown to us, and that ’tis in vain that we search for it in all the known qualities of matter. (159/1.3.14.8)
But [NI] it exists, for there must be some reason, in nature, why things are regular in the way they are. It’s just that we can’t know anything about it. If we did know about it, Hume thinks, we would have to be able to make a priori certain inferences about causal matters (see 11), and we know we could never do this. We‘have no adequate idea of power or efficacy in any object’ (160/1.3.4.10).
Another reason why we can’t know anything for sure about it (the point bears repetition) is that we can’t even rule out Berkeley’s hypothesis about the nature of the world and the power (the volition of a divine, immaterial, active substance) that gives it its order. As the Humean Philo says in the Dialogues,
our experience, so imperfect in itself, and so limited both in extent and duration, can afford us no probable conjecture concerning the whole of things (133/178).
But if we know so little about the world as a whole and the power that informs or governs it that we can’t even decide between a more or less Lockean account of it and a Berkeleian account of it (let alone a Malebranchean account of it), and (further- more) can’t even conceive of what sort of humanly accessible evidence could ever give us grounds for making a definite choice between these hypotheses, then it’s very clear indeed that we don’t really know anything for sure about its ultimate nature.2
For this reason alone, even if for no other, the seventeenth-century belief in ‘intelligible causes’—in the possibility of knowledge of the true or ultimate nature of nature—can be seen to be a delusion. And this belief is one of Hume’s main targets.3
Still in 1.3.14, Hume speaks of our never having any
(4) [EP] insight into [REF] the internal structure or operating principle of objects, having just remarked that
(5) [REF] the uniting principle among our internal perceptions is as [EP] unin- telligible as that [the uniting principle] among external objects,
which nonetheless certainly exists, and is real, although we can never know anything about its ultimate nature.4Clearly he can’t here mean the ‘principles of association of ideas’ by ‘the uniting principle among our internal perceptions’, for the principles of
2 The respectability of the notion of the ultimate nature of reality was defended in 7.
3 More particularly, many philosophers thought that they had some a priori insight into the nature of causation of a sort that allowed them to conclude with certainty that all causation or‘active power’ must be mental or spiritual in nature; see Wright 1983: 163, and ch. 20 n. 6 below.
4
169/1.3.14.29. It seems clear that these external objects must be construed in a straightforwardly realist way, or at the very least in a basic-realist way—as must ‘nature’ in quotation (3). For if objects are just pc objects or pcc objects (cf. 6.2), then they don’t really have any concealed, internal structure. (In fact, even if one gives the words‘external object’ a non-basic-realist construal, here, interpreting them as pc objects or pcc objects, it seems that one is still left with a referring expression referring to Causation—to the completely unknown‘operating principle’ of objects whatever their ultimate ontic nature; i.e. whether they are purely mental or not.)
association of ideas are fully intelligible. He explicitly states what they are (resem- blance, contiguity, and causation), and what they amount to. So‘the uniting principle among our internal perceptions’ must mean, roughly, ‘whatever in-itself-unknown power or principle of operation makes our minds operate observably as they do’—the way in which our minds operate observably being fully captured by the description of the principles of association of ideas. In an exactly similar fashion, Newton’s laws capture observable aspects of the theory-of-ideas unintelligible (E-unintelligible) ‘uniting principle’ among external objects (see 20 below).5
To these examples we may add one from the‘Abstract’, where Hume says that (6) [REF] the powers, by which bodies operate, are [EP] entirely unknown.
(652/Abs}15)
I think I can imagine how commitment to the standard view of Hume’s account of causation may make it possible for some readers to read passages like these auto- matically as confirmation of the standard view. For such readers, Hume’s epistemo- logical, sceptical point about the complete undetectability of Causation still immediately generates the profoundly un-Humean ontological claim about the definite nonexistence of any sort of Causation. But one can no longer react like this once one has understood Hume’s strictly non-committal scepticism with regard to knowledge claims about what does or doesn’t exist, and his commitment to the idea that it’s intelligible to suppose that there are things that are completely unintelligible to us, and of which we can only have a‘relative’ idea; not to mention his realist or basic-realist beliefs, which are fully compatible with his scepticism, since his scepti- cism emphatically allows that these beliefs are R-intelligible (12.2), intelligible in the broad sense, and may in fact be true, insisting only that we can never know for sure whether they are or not.
Objection. Hume is only saying that‘the reason of the conjunction’ of any two objects, the ‘ultimate force and efficacy of nature’, ‘the powers, by which bodies
5 Insofar as we are able to work out the principles of association of ideas we are able to‘discover, at least in some degree, the secret springs and principles, by which the human mind is actuated in its operations’ (14/1.15), although we cannot ever grasp the nature of the‘ultimate principle’ which governs the mind. In fact, though, Hume thought that we could go a little further. His discussion of the principles of association of ideas in 1.2.5 is of particular interest. He begins by referring to 13/1.1.4.6, where he says that the causes of the mind’s operating according to the principles of association of ideas ‘are mostly unknown, and must be resolv’d into original qualities of human nature, which I pretend not to explain’. But he then (following Malebranche and Mandeville) goes on to offer as his own a fullyfledged if very general neurological explanation of why the mind operates as it does:‘the mind is endow’d with a power of exciting any idea it pleases; whenever it despatches the spirits into that region of the brain, in which the idea is plac’d; these spirits always excite the idea, when they run precisely into the proper traces, and rummage that cell, which belongs to the idea. But as their motion is seldom direct, and naturally turns a little to the one side or the other—for this reason the animal spirits, falling into contiguous traces, present other related ideas in lieu of that which the mind desir’d at first to survey’ (60–1/1.2.5.20). The nature of the ‘ultimate principle’ by which the brain thus operates is still entirely unknown and unintelligible, on this view, as is the nature of all causal power. Nevertheless we can give some kind of real explanation of why the principles of association of ideas govern our thought as they do, by reference to the nature of the brain.
operate’, and so on, are perfectly unknown, and not in fact unknowable. Reply: since Hume holds that all that could ever become known to us, so far as causation in the objects is concerned, are regularities of succession, this objection must suppose that all Hume means by speaking of the‘perfectly unknown . . . ultimate force and efficacy of nature’ (etc.) are other as yet undetected (presumably because much smaller) regularities of succession. The idea is then presumably that, given knowledge of minute regularities of succession between Cs and Ds, Es and Fs, say, we might come to see why there is some larger-scale regularity of succession—between As and Bs, say.
Three points may be made in reply to this suggestion; two have been made already. First, it’s highly unnatural to read such phrases in this way.6Second, one of Hume’s
explicit reasons why we can’t know the true nature of power is that if we did then we would be able to make a priori certain inferences about causal matters of a sort we know we cannot make. Learning about minute regularities of succession couldn’t help with this. Third, since we can’t even decide between Lockean and Berkeleian accounts of the true nature of reality, we can’t possibly suppose that we could ever know the nature of‘the ultimate force and efficacy of nature’.
It’s true that Hume does sometimes think of causes as being unknown in the sense that there are regularities of succession which are unknown but potentially discov- erable. But this doesn’t alter the fact that he thinks of the ‘ultimate force and efficacy of nature’ as something totally inaccessible to us. This issue is discussed further in 18.
6 The reading is offered in support of the‘standard’ view; but only a prior presumption that the ‘standard’ view is true can give one reason to favour it.