Experience and reasoning: challenging the a priori/a posteriori distinction

Williamson and others have recently argued against the significance of the a priori/a posteriori distinction. My aim in this paper is to explain, defend, and expand upon one of these arguments. In the first section, I develop in some detail a line of argument sketched in Williamson (The philosophy of philosophy, Blackwell Publishing, Oxford, 2007). In the second section, I consider two replies to Williamson and show that they miss the structure of the challenge, as I understand it. The problem for defenders of the distinction is to find a way to draw it without leaving out some paradigmatic a priori knowledge or including some paradigmatic a posteriori knowledge. Interestingly, the two replies fail in opposite directions. I then consider the view that, in cases of a priori knowledge, one needs only understanding and some reasoning to gain justified belief. Such reasoning, I argue, should itself not be dependent on experience. Next, I consider, and reject, the attempt to spell out independence of experience for reasoning based on a link between the modal and epistemic status of the proposition involved. Finally, I provide some general grounds to think that the role of experience in forming a reasoning competence, while not evidential, is not devoid of normative value. The main reason is that the normative status of intellectual competences depends on the experiences that constitute their acquisition and development.