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?

I believe, that empirically informed approaches to the question have issued in more illuminating answers than the old armchair approaches. But I think that it would be a terrible mistake to give up on addressing normative questions in epistemology.

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.

There is a worry that many have expressed that, on the naturalistic way of approaching philosophical questions, philosophy will somehow be co-opted by science. I'm not much worried about this.

Work on causal theories of knowledge - early work by Armstrong, and Dretske, and Goldman - seemed far more satisfying. As I started to see the ways in which work in the cognitive sciences could inform our understanding of central epistemological issues, my whole idea of what the philosophical enterprise is all about began to change. Quine certainly played a role here, as did Putnam's (pre-1975) work in philosophy of science, and the exciting developments that went on in that time in philosophy of mind.

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.

The role of empirical work in informing our philosophical theories, as I see it, is not that it gives us a better view of our folk concepts, but that it gives us a better view of knowledge, and the mind, and so on.