Abstract: This chapter contends that proponents of the a priori face two major challenges: articulating the experiential/nonexperiential distinction, and providing supporting evidence for the claim that there are nonexperiential sources of justification. It is argued that the most promising approaches to addressing both challenges involve empirical investigation. With respect to the first, “experience” should be viewed as a natural kind term whose extension is fixed by certain paradigms. The underlying nature of the paradigms must be uncovered by empirical investigation. With respect to the second, it is argued that providing compelling support for the a priori involves two related projects: the Articulation Project, whose goal is to more fully articulate the claim that there are nonexperiential sources of justification; and the Empirical Project, whose goal is to provide empirical supporting evidence for the articulated claim.

Keywords: a priori, articulation project, empirical project, experience, experiential, justification, nonexperiential, natural kind, source,