The Justification of A Priori Intuitions

There are propositions that upon understanding them it seems that one can that they are necessary or impossible. A commonly discussed example is the claim that it is not possible for an object to be red and green all over at the same time. My purpose in this paper is to account for how it is that such beliefs are justified. I begin by criticizing a suggestion defended lately by Laurence BonJour and others.' BonJour argues that because these beliefs are necessarily true external factors are irrelevant to their epistemic status. This is how BonJour can defend a foundationalist account of the a priori while at the same time attacking foundationalism with respect to empirical knowledge. I argue that this view of the a priori is mistaken. External factors are relevant even in the case of those a priori beliefs it seems we can just see to be true. I defend an alternative account of the justification of such beliefs. I argue that these beliefs may be justified in virtue of their being the products of a basic belief-forming mechanism one has no reason to distrust. In particular, I argue that this approach can be employed to account for the non-inferential justification of a priori beliefs without falling prey to the line of objections BonJour lodges against other forms of foundationalism.