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.

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.

My own reasons for favouring talk of natural kinds is just that I believe the best accounts of the success of scientific theories presupposes the existence of natural kinds.

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 think that when I first suggested the idea that knowledge should be viewed as a natural kind, many people thought this was just crazy.

The kind of approach I take is different from much of experimental philosophy. Although the experimental philosophers and I are certainly in agreement about the relevance of empirical work to philosophy, a good deal of their work is devoted to understanding features of our folk concepts, and in this respect, at least, I see them as making the same mistake as those armchair philosophers who are interested in conceptual analysis.

When reflection is thereby demystified, I believe that the temptation to view human knowledge as different in kind from animal knowledge is undermined.