Hume on Causes

The great British empiricist philosopher David Hume (1711-1776) wrote that “There are no ideas which occur in metaphysics more obscure and uncertain than those of ‘power’, ‘force’, ‘energy’, or ‘necessary connection'” (An Inquiry Concerning Human Understanding, Library of Liberal Arts ed., p. 73).

Hume is most famous for his critique of naive or dogmatic assumptions about causality. “[T]here is not, in any particular instance of cause and effect, anything which can suggest the idea of power and necessary connection” (p. 75). To me, it seems to be the idea of an underlying power or force responsible for causality that he is mainly questioning. He has no doubt that we continually experience instances of cause and effect.

“[There is] no such thing as chance in the world” (p. 69). “[T]he conjunction between motives and voluntary actions is as regular and uniform as that between the cause and effect in any part of nature” (p. 98). Clearly, then, he did believe in the reality of cause and effect, but only wanted to reject naive claims about our knowledge of the world that purport to link experienced instances of cause and effect to explanations in terms of the operation of underlying powers. What we actually experience in these cases is just lawful regularity.

“It is certain that the easy and obvious philosophy will always, with the generality of mankind, have the preference above the accurate and abstruse…. The fame of Cicero flourishes at present, but that of Aristotle is utterly decayed” (pp. 16-17). But on the other hand, “All polite letters are nothing but pictures of human life in various attitudes and situations…. An artist must be better qualified to succeed in this undertaking who, besides a delicate taste and a quick apprehension, possesses an accurate knowledge of the internal fabric, the operations of the understanding, the workings of the passions…. However painful soever this inward search or inquiry may appear, it becomes in some manner requisite to those who would describe with success the obvious and outward appearances of life and manners…. Accuracy is, in every case, advantageous to beauty, and just reasoning to delicate sentiment. In vain would we exalt the one by depreciating the other” (p. 19). Clearly, then, Hume’s polemic against scholastic modes of reasoning does not at all mean he simply rejects the values of “accurate and abstruse” philosophy.

Neoplatonizing tendencies in the Aristotelian commentary tradition led to the common Latin scholastic view of causes as metaphysical powers operating behind the scenes that Hume is mainly concerned to criticize. Aristotle himself identified causes more broadly and much less speculatively with every kind of “reasons why” things are as they are and behave as they do. He did so without making extravagant claims to certain knowledge. Whereas scholastic philosophers characteristically debated the pros and cons of accepting various abstract propositions, Aristotle himself was fundamentally concerned with the use of reason to help interpret concrete human experience (see Aristotelian Causes).

Hume is a great philosopher, and so far I have focused on a positive appropriation of his work, having some points in common with themes I have been pursuing about causality and the notion of power. Robert Brandom’s innovative reading of Kant’s response to Hume points out that there are distinct limits to Hume’s approach.

“Kant read Hume’s practical and theoretical philosophies as raising variants of a single question. On the side of practical reasoning, Hume asks what our warrant is for moving from descriptions of how things are to prescriptions of how they ought to be. How can we rationally justify the move from ‘is’ to ‘ought’? On the side of theoretical reasoning, Hume asks what our warrant is for moving from descriptions of what in fact happens to characterizations of what must happen and what could not happen…. Hume’s predicament is that he finds that even his best understanding of facts doesn’t yield an understanding of either of the two sorts of rules governing and relating those facts, underwriting assessments of which of the things that actually happen (all he thought we can directly experience) ought to happen (are normatively necessary) or must happen (are naturally necessary).”

“Kant’s response to the proposed predicament is that we cannot be in the situation that Hume envisages: understanding matter-of-factual empirical claims perfectly well, but having no idea what is meant by modal or normative ones” (Brandom, Reason in Philosophy, p. 54).

Brandom continues, “To judge, claim, or believe that the cat is on the mat, one must have at least a minimal practical ability to sort material inferences in which that content is involved (as premise or conclusion) into good ones and bad ones, and to discriminate what is from what is not materially incompatible with it. Part of doing that is associating with those inferences ranges of counterfactual robustness…. So, for example, one must have such dispositions as to treat the cat’s being on the mat as compatible with a nearby tree being somewhat nearer, or the temperature a few degrees higher, but not with the sun being as close as the tree or the temperature being thousands of degrees higher. One must know such things as that the cat might chase a mouse or flee from a dog, but that the mat can do neither, and that the mat would remain essentially as it is if one jumped up and down on it or beat it with a stick, while the cat would not. It is not that there is any one of the counterfactual inferences I have mentioned that is necessary for understanding what it is for the cat to be on the mat. But if one makes no distinctions of this sort — treats the possibility of the cat’s jumping off the mat or yawning as on a par with is sprouting wings and starting to fly, or suddenly becoming microscopically small; does not at all distinguish between what can and cannot happen to the cat and what can and cannot happen to the mat — then one does not count as understanding the claim well enough to endorse it” (pp. 54-55).

Brandom concludes, “If that is right, then in being able to employ concepts such as cat and mat in ordinary empirical descriptive claims one already knows how to do everything one needs to know how to do in order to deploy concepts such as possible and necessary — albeit fallibly and imperfectly” (p. 55).

I am actually a little more sympathetic to Hume, in that I don’t read him as categorically rejecting the validity of concepts of necessity, only any possibility of certain knowledge of how they apply to the real world. I personally like the position of Leibnitz that necessity is real but always hypothetical, never categorical. But Brandom is right that Hume does not go on to emphasize how essential our fallible understanding of necessity is to our understanding of ordinary experience.