Aune, Bruce - An Empiricist Epistemology Ch 2 "A Priori Knowledge and the Claims of Rationalism"

05/11/2007

Unpublished Manuscript

This chapter is devoted to giving doubts to the anti-empiricist rationalist philosophies that claim support of a priori knowledge like "nothing can be green or yellow at the same time" or 'not (P and not P)'.

Author wants to distinguish between a priori knowledge and analytic knowledge. At issue here is whether commonly thought of a priori claims (not necessary identity and contingent a priori claims made by Kripke, by the way) can be proved or verified. The proof would be possible given a combination of axioms and inference. But now we are given to another question: what axioms do we use? Here the rationalist believes the axioms used are knowable by direct intuition. Author complicates this picture by showing that axioms are superfluous because they are derivable from rules, and further that the claim that anything is knowable by direct intuition is dubious (pg 46-). The contrary view is the empiricist's, whose standard claims are that the rules of inference are underwritten by convention that aims at preserving truth using 'semantical rules' (pg 42, top).

Author discusses that it is true that sometimes things are immediately apprehendable; but these things are like recognizing faces, or my own hand. Author does not believe that recognizing that things are of a given kind is as intuitive. For instance, we need to recognize the appropriate application conditions of modus ponens before we can use it in inference. Without taking a situation (or set of propositions) to be an instance where modus ponens properly applies, we can easily go wrong. Author uses two examples of moral and geometrical cases.

Author then takes on the standard cases that make up the rationalist backbone. E.g., the law of non-contradiction is complicated by non-self-referential liar-like-paradoxes. The law of the excluded middle is complicated by supposedly vague predicates 'is bald', 'has a beard', 'is a tree/sapling', 'is a child/adult'. Author also discusses 'nothing can be both red and green all over at the same time' and indicates that this happens to be more a matter of physiology than a property of the world, as an exercise, change 'red/green' to 'yellow/green' and you can have 'yellowish-green' and 'greenish-yellow'.

Lastly, author reviews the more modern cases of Kripkean necessary identity and contingent a priori. He claims these can possibly be shown to be analytic, and he will try to do so in the next chapter.