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.

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 these scientific theories have a fine track record of successful prediction and explanation speaks for itself. (Which is not to say that I don't directly discuss the work of those philosophers who would disagree.) But even if we grant this, many will argue that scientific knowledge in humans, and, indeed, reflective knowledge in general, is quite different in kind from the knowledge we see in other animals.

The kinds of claims I make about knowledge are thus meant to be illustrative of a general argumentative strategy which might well bear fruit in areas of philosophy which I have not thus far explored.

No one worries terribly much about who the questions belong to, or whether a given contribution is really philosophy or, instead, properly nothing but science. Perhaps another way to put this is that, although I think that knowledge is a natural kind, I don't think that philosophy is.

I do think that an understanding of contemporary work in the cognitive sciences has a profound effect on how one views the workings of the mind. It doesn't work the way we pretheoretically think it does. Such an understanding, of course, should have a large effect on one's views in philosophy of mind, but also in epistemology.

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.