Kieran Setiya has some skeptical thoughts on the X-phi movement here. It's a very interesting post, based on some cogent considerations regarding the seeming ineliminability of a priori knowledge in the X-phi method itself.
I have two inchoate thoughts. First, I'm not sure it's fair to view X-phi as a philosophical position that denies the possibility of a priori knowledge per se. Rather, one could view X-phi merely as a complement to the more speculative philosophizing that the "armchair method" represents.
This objection to Kieren's post is inchoate because I'm not really sure I've got the sociological facts straight. (E.g., maybe Josh Knobe really thinks that there is no such thing as a priori knowledge of contingent facts. I'm not familiar enough with his work to say.)
Second, continuing to view X-phi as a philosophical position that deprecates a priori knowledge, the argument might be not that a priori knowledge of the contingent doesn't exist so much as it is that such knowledge is subject to defeat by empirical discovery. I think it would be fair, for instance, to say that Einstein had knowledge that mass and energy was equivalent. Arguably, this counts as "a priori" knowledge; while Einstein relied on empirical findings about the speed of light in developing the idea, he also relied on several paradigmatically "a priori" principles (e.g., the principle of relativity itself). And, also arguably, this insight counted as knowledge before it was ever tested. But - Einstein's knowledge, such as it was, would have been defeated had later tests gone the other way. If that's right, then the empirical has epistemic priority over the a priori.
This second objection to Kieren's post is inchoate because in the standard case, a single empirical experiment won't soundly falsify a theory. Armchair speculation may provide ad hoc, a priori insights that preserve the theory. In which case, the armchair beats (or at least ties) the laboratory. So it's a bit quick to say that the empirical has priority over the a priori. I'll have to leave it at that. Go read Kieran's post.
