Here, as in so many other cases, however, it turns out that a very commonsensical idea looks far less attractive when one examines some of the experimental work which is not available to us from the armchair.

17th century philosophers were not in a position to understand the mind as well as we can today, since the advent of experimental methods in psychology. It shows no disrespect for the brilliance of Descartes or Kant to acknowledge that the psychology which they worked with was primitive by comparison with what is available today in the cognitive sciences, any more than it shows disrespect for the brilliance of Aristotle to acknowledge that the physics he worked with does not compare with that of Newton or Einstein.

I argue is that philosophers have had a tendency to present a kind of mystical view of the powers of reflection. Unreflective belief acquisition is seen in mechanistic terms, but when philosophers talk about reflection, it is as if reflective processes are not bound by the kinds of limitations which inevitably arise from being embedded within the same causal structure which governs unreflective belief acquisition.

I was often asked how one could even make sense of this. Isn't the category of knowledge something that we project upon the world, rather than something that we discover in it?

The fact that these scientific theories have a fine track record of successful prediction and explanation speaks for itself. (Which is not to say that I don't directly discuss the work of those philosophers who would disagree.) But even if we grant this, many will argue that scientific knowledge in humans, and, indeed, reflective knowledge in general, is quite different in kind from the knowledge we see in other animals.

I am certainly open to the idea that this might be used to explain other philosophical categories besides knowledge. I have some real sympathy with the work of those moral realists who have tried to give naturalistic accounts of human flourishing, and who offer accounts of right action in such terms. (I suppose this is more evidence that I really do have deep affinities with Aristotle!)

I do think that it is legitimate to talk of goals and functions in nature, and that these things can be made sense of in naturalistic terms. There is nothing at all contrary to naturalism in the idea of goal-directed systems.