ABSTRACT
Reichenbach considered a position on a priori knowledge that is a dynamic theory of the constitutive elements in science, as he forcefully distinguished between the constitutive role of the a priori and its claimed necessity. Moritz Schlick considered the possibility that Einstein's principle of relativity might conflict with our a priori intuitions in a Kantian sense, but in his later works, Schlick rejects the Kantian a priori entirely. Michael Friedman has shown that Reichenbach's views on the a priori changed after an exchange of letters with Schlick. Treating conventionalism as a metamathematical thesis led to the charge of trivial semantic conventionalism, a trivial linguistic thesis made Logical Empiricism vulnerable to the criticisms raised in Quine's Two Dogmas of Empiricism. Ayer collapses the Kantian synthetic a priori, interpreting everything that had been in that category either as purely analytic or else as empirical and therefore not a priori at all.
