Abstract
This paper offers an account of the a priori. According to this account, the fundamental notion is not that of a priori knowledge, or even of a priori justified belief, but a notion of an a priori justified inferential disposition. The rationality or justification of such a priori justified inferential dispositions is explained purely by some of the basic cognitive capacities that the thinker possesses, independently of any further experiences or other conscious mental states that the thinker happens to have had. It is then shown how a priori justified inferences and beliefs can be explained on the basis of such a priori justified inferential dispositions.