Chemists in earlier centuries were quite interested in the nature of acids. They had no interest in analysing their concept of acid. After all, they knew that their understanding of acids was at a fairly primitive level, and what they wanted to do was understand something about the world better - the nature of acidity - not something about their own concepts.

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.

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?

It's not just that there is a cooperative spirit of investigation there, where we all recognise that we are engaged in a common project of inquiry. It's also that the philosophers are well-versed in the relevant empirical data, and the scientists are well-versed in the more abstract issues which are typically the central focus of philosophical work.

I don't know whether I can say that having a career in philosophy has turned out as I imagined, since in many ways I had little idea of what such a life would be like. But philosophy is still tremendously exciting to me, and the opportunity to think, and talk, and write about these issues has been wonderful.

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.

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.