Chapter 41 A priori knowledge *

'A P.RIO~I' has been a popu~ar .term with phil?s~phers at least since Kant distmgmshed between a pnon and a postenon knowledge. Yet, despite the frequency with which it has been used in twentieth century philosophy, there has been little discussion of the concept of apriority. 1 Some writers seem to take it for granted that there are propositions, such as the truths of logic and mathematics, which are a priori; others deny that there are any a priori propositions. In the absence of a clear characterization of the a priori/a posteriori distinction, it is by no means obvious what is being asserted or what is being denied. 'A priori' is an epistemological predicate. What is primarily a priori is an item of knowledge. Of course, we can introduce a derivative use of 'a priori' as a predicate of propositions: a priori propositions are those which we could know a priori. Somebody might protest that current practice is to define the notion of an a priori proposition outright, by taking the class of a priori propositions to consist of the truths of logic and mathematics (for example). But when philosophers allege that truths oflogic and mathematics are a priori, they do not)ntend merely to recapitu-