Full Idea
I am a fully paid up-naturalist, but I see no reason to deny that a priori knowledge is possible. My view is that a priori knowledge is unimportant (esp to philosophy). If there is a priori knowledge, it is analytic, true by the structure of our concepts.
Gist of Idea
A priori knowledge is analytic - the structure of our concepts - and hence unimportant
Source
David Papineau (Philosophical Insignificance of A Priori Knowledge [2010], §1)
A Reaction
It is one thing to say it is the structure of our concepts, and another to infer that it is unimportant. I take the structure of our concepts to be a shadow cast by the structure of the world. E.g. the structure of numbers reveals the world.