Why the Fregean “Square of Opposition” Matters for Epistemology

Abstract

A relevant issue for epistemology is the distinction between expression of a “judgeable content” and “judgment”. We would suggest that Frege’s enterprise in the Begriffsschrift seems to be devoted to describe this difference from a formal point of view. For, he considers an expression as a simple or complex sign characterized by the function/argument structure. In our contribution, we try to elucidate Frege’s effort by analyzing his variation of the Aristotelian “square of opposition” and by following his logical steps from an “epistemological” point of view which overcome the classical Aristotelian syllogism but plausibly respects the fundamental distinction between “judgeable content” and “judgment”.