Abstract

BonJour’s intricately argued and provocative book raises a fundamental challenge for the empiricist: if we lack the capacity for direct apprehension of necessary truths, how do we know so much? How do we know about logic and mathematics and other apparently a priori subjects? How do we know about generalities, about the past and the future, about objects that are not present? How do we know about the relations that hold between premises and conclusions? If the first half of BonJour’s book is right, the empiricist is unable to answer these questions, for she is unable to explain how our beliefs in such things are justified. Lacking such an explanation, the empiricist would be committed to an extreme and unacceptable form of skepticism—call this the indispensability argument. The rationalist, by contrast, has an answer to these questions, and if the second half of BonJour’s book is right, the answer is both epistemologically and metaphysically unobjectionable— call this the possibility argument.