Naturalized epistemology

1. Hume’s anticipation of naturalized epistemology

The naturalizing movement in epistemology is the continuation of Hume’s rebellion against Descartes’ view about knowledge. Like Descartes, Hume wanted to conduct an investigation of the mind and its operations, including ‘the operations we perform in our reasonings’. But five features of Hume’s approach place him far closer to contemporary naturalism than to Cartesianism.

First, while Descartes wished to leave no room for doubt, Hume explicitly took for granted the trustworthiness of the very faculties whose operations he wanted to investigate. Later naturalists (theorists who identify with the label ‘naturalized epistemology’) make a parallel move: they trust the techniques and assumptions of science even while investigating how (scientific) knowledge is possible. Hume assumed that our mental faculties are trustworthy because it would be pointless to attempt to test their accuracy; after all, any test required their use. In fact, it was because Hume supposed that the mental faculties generated knowledge (or at least rational belief) that he thought the clarification of their workings would shed light on the normative question of what an epistemic agent ought to believe. His project still had a critical edge, for when Hume found any belief that could not be satisfactorily accounted for in terms of standard human faculties, he recommended throwing it out as baseless.

Second, like later naturalists, Hume modelled his epistemology after the emerging natural sciences, where empirical confirmation served as the basis for claims. He thought that knowledge encompasses everything we can discover using all our mental faculties, including experience and what we can discover by applying our mental faculties to themselves.

Third, like contemporary naturalists, Hume was prepared to say that some knowledge is the product of purely causal mechanisms rather than reason (or reasoning), since through introspection Hume thought he could detect a causal mechanism at work. The mechanism he detected itself produces knowledge of causal relations, on the basis of which we believe in matters of fact, which are facts that hold contingently and whose negations indicate real possibilities (see Hume, D. §2; Causation §1). Custom, prompted by experience, is the mechanism through which we form our suppositions concerning causal relations. Hume does not recommend doubt about the products of custom. After all, the mind is functioning in a healthy, normal way when it is under the influence of custom, and reasoning can begin only after custom does its work. We should begin to question our beliefs only when we find that they are arrived at while the mind is not functioning in the normal way science describes.

Fourth, like many contemporary naturalists, Hume explains some of the mechanisms responsible for knowledge (such as custom) in terms of survival value. The linking of causes to effects is so important to human survival that it would have been a mistake for ‘nature’ to entrust it to our reason ‘which is…extremely liable to error’. Better to entrust it to ‘some instinct or mechanical tendency, which may be infallible in its operations, may discover itself at the first appearance of life and thought, and may be independent of all the laboured deductions of the understanding’ (Hume [1748/51] 1975: 55). Years later, W.V. Quine and other naturalists will speak in the same vein. Quine (1974: 20) explains induction in terms of natural selection, and disavows any claim to have justified induction. ‘In the matter of justifying induction we are back with Hume, where we doubtless belong’.

Fifth, Hume is with contemporary naturalists in their reactions to scepticism. As he had to, since he put his trust in his faculties, Hume rejected Descartes’ idea that to know that our beliefs are true is to be in a position to place all our beliefs beyond doubt at once. Hume saw that it is not even possible to justify all our views at once. No more than Descartes could Hume use his faculties to assess his epistemic prospects without first assuming that they were reliable. In the last section of the Enquiry Concerning Human Understanding (1748/51), Hume mentions scepticism and simply acknowledges that truly global doubts would be ‘entirely incurable’.