Philosophical disagreements about whether there is a distinction between a priori and a posteriori knowledge is typically conflated with a disagreement about the possibility of a priori knowledge itself. This is because very few people doubt the existence of a posteriori knowledge or what it is, so the survival of the distinction inevitably is dependent on the survival and/or the characterisation of the a priori.
But whether knowing anything a priori is actually possible has still not found philosophical resolution. Naturalism, for instance, has provided a steady offensive against the possibility of a priori knowledge. And, inevitably, most often the rebuttals have come from within the rationalist camp. But, it is argued here, a defence of the a priori which does not use the most robust analysis of the concept is bound to fail at the outset. Such a robust account does necessarily come from the rationalist camp.
This paper aims to correct one such defence of the a priori and therefore of the distinction: Casullo’s ‘Four challenges to the a priori-a posteriori distinction’ – which is in fact four challenges to the a priori. It further aims to suggest a more robust construal of a priori, by suggesting an anti-realist analysis of ‘a priori knowledge’.