Abstract: The account of warrant I propose, utilizing the notion of proper function as it does, is an example of naturalistic epistemology: it invokes no kind of normativity not to be found in the natural sciences; in this chapter and the next, I argue that naturalism in epistemology can flourish only in the context of supernaturalism in metaphysics. To do so, I argue that there is no satisfactory naturalistic explanation or account of the notion of proper function (or related notions like purpose, malfunction, design plan, etc.). I consider proposals for such an account that can be drawn from the work of John Pollock, Ruth Millikan, and John Bigelow and Robert Pargetter, but find in each case that the proposed account is inadequate. I then consider the possibility that the notion of proper function (and related notions) should be thought of as useful fictions. After some critical comments about this possibility, I proceed to point out that if one (1) is convinced that there really is such a thing as warrant and that there really is (for natural organisms) such a thing as proper function, and also (2) thinks that there is no naturalistic analysis of these notions, then one has a powerful argument against naturalism.

Keywords: Bigelow, Millikan, naturalism, naturalistic epistemology, Pargetter, Pollock, proper function, warrant,