Abstract

Laurence BonJour divides approaches to a priori justification into three kinds. Quine’s radical empiricism denies the existence of any special category of a priori justification; moderate empiricism attempts to explain a priori justification in terms of something like knowledge of meaning or grasp of concepts; and rationalism postulates an irreducible ‘rational insight’ into the nature of reality. The positions therefore form a familiar trio of eliminativism, reductionism and anti-reductionism concerning a priori justification. BonJour’s interesting and (in the present philosophical climate) unusual project is to defend rationalism, the anti-reductionist position. Rationalism says that we have an ability to ‘directly or intuitively see or grasp or apprehend … a necessary fact about the nature or structure of reality’ (pp. 15-16). ‘An apparent rational insight,’ he says, ‘purports to be nothing less than a direct insight into the necessary character of reality’ (p. 107). Two clarifications will help to mark out the distinctive character of this view: first, that rational insight is fallible; and second, that although BonJour carefully distinguishes the concepts of necessity and apriority, he none the less claims that rational insight yields a priori knowledge of necessary truths only. On his view, the contingent a priori does not exist, although empirical necessities do...