I have made some headway in addressing these questions, however, and succeeded in explaining how it is that the category of knowledge might play an important role in empirical theories. To the extent that talk of knowledge can be shown to play an explanatory role in such theories, the analogy I wish to make with paradigm natural kinds such as acids and aluminum starts to make a good deal of sense. This is, of course, connected with the issue of the role of intuitions in philosophy.

Epistemologists should be concerned with knowledge and justification and so on, not our concepts of them; philosophers of mind should be concerned with various features of our mental life and the large-scale structure of the mind, not our concepts of mind, or consciousness, or anything else

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.

So I do, of course, reject much that is central not only to the psychology of Descartes and Kant, but to their epistemology as well. No doubt, the best available theories of today will look primitive in comparison with what we are in a position to understand hundreds of years from now.

When I got to college, I planned to be a math major, and, in addition to signing up for some math courses, I decided to take some philosophy. Quite by chance, I took a philosophy of science course in which the entire semester was devoted to reading Locke's Essay. I was hooked. For the next few semesters, I took nothing but philosophy and math courses, and it wasn't long before I realised that it was the philosophy that really moved me.

Externalists reject any such view. I think that the idea that we can tell, simply by way of reflection, whether our beliefs are justified, is deeply commonsensical. More than that, the idea that responsible epistemic agents ought to reflect on their beliefs, and hold them only if they somehow pass muster, is utterly natural.

The fact that we have been able to develop a successful science, which issues in ever more accurate predictions and broader explanations, is the real ground for confidence that we are in a position to gain knowledge of the world around us. At the same time, one might ask how it is that the cognitive equipment we have came about, and here, no doubt, our evolutionary origins are relevant.