Is Foundational A Priori Justification Indispensable?

Abstract

Laurence BonJour argues for a rationalist position according to which pure reason can discover substantive truths about the world.¹ Rationalism has been dominant throughout the history of philosophy, but in recent years the development of philosophical naturalism has diminished its prestige. Naturalism holds that reason’s putative grasp of these truths can either be explained away in terms of convention or dismissed entirely. The first move explains reason’s putative grasp of these claims in terms of definitions and trivial implications between synonyms. This view is associated with moderate empiricism. The other naturalist move takes aim against the distinctions and concepts upon which the traditional debate over the a priori relies. BonJour focuses on Quine’s radical empiricism in this connection. One of the themes I return to is that BonJour doesn’t appreciate the depth of Quine’s criticism of the traditional rationalist-empiricist debate. I restrict my attention to BonJour’s indispensability arguments. He argues that unless one is a radical skeptic about justification, there must be some substantive a priori justification. ² BonJour refers to this argument as “the master argument” of his book.³ He argues that unless there is some substantive a priori justification then no reasoning is ever justified and no one is ever justified in believing any claim that transcends experience.