No one would suggest that we can adequately investigate what makes something an acid, or what makes something aluminum, by bringing our pretheoretical intuitions about these things into reflective equilibrium by way of armchair theorising.

The experimentalists think that we can only get at our concepts by way of empirical investigation, while the armchair philosophers think that we can skip the experiments and figure things out from our armchairs. What they have in common, however, is regarding our concepts as the targets of philosophical theorising, and I just don't think that, in the vast majority of cases, the subject matter of philosophy has our concepts as its target.

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

Rather, although belief may be adequate for explaining the behavior of individual animals - an animal which believes that p will behave no differently from an animal which knows that p - talk of knowledge is necessary once one begins to look at explaining the cognitive capacities of a species.

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.

If we want to make sense of the possibility of successful inductive inference, and if we want to explain the possibility of laws of nature, we will need to appeal to something like natural kinds. This is, to be sure, a metaphysical commitment, but it is a metaphysical commitment that is implicit in science, as I see it.