ABSTRACT

Apriori (or a priori) knowledge is often taken to be exemplified by logic and arithmetic, where sense experience is thought to be irrelevant. Aposteriori (or a posteriori) knowledge is often taken to be exemplified by physics and chemistry, where it is thought that self-evidence and intuition must be supplemented with experimental data based on sense experience. However, usage varies. For some philosophers, apriori beliefs are known with absolute certainty and aposteriori beliefs are relatively suspect. For others, apriori beliefs are mere prejudices that have not been subjected to unbiased investigation and aposteriori beliefs are relatively reliable. Moreover, some philosophers seem to assume that epistemic processes leading to apriori beliefs are infallible and thus that all apriori beliefs are knowledge, known to be true. Other philosophers readily grant that the mistakes occurring in the history of logic and mathematics provide ample proof to the contrary.