Prelude: Poincaré, Wittgenstein, Peirce, and the use of concepts

Abstract

The fact that categorial concepts are used despite the difficulties in giving them satisfactory set-theoretical foundations leads to the idea of studying first of all the use of these concepts, their pragmatic aspect. More specifically, workers in the field seem not to ask whether the concepts are legitimate in the sense that they refer to some objects which exist but whether they are used in a legitimate way. We have to analyze, hence, what it means for a use to be legitimate.