Peirce on Vagueness and Common Sense

“Issues of Pragmaticism” (1905) contains the only published version of Peirce’s doctrine of “critical common-sensism.” One of the claims of that doctrine is that common sense beliefs are invariably vague. In this paper, we seek to explain this claim. We begin by providing a philological reconstruction of the drafts of “Issues of Pragmaticism” and a comparison of Peirce’s several, successive expositions of critical common-sensism across those drafts. Then we examine Peirce’s theory of vagueness; we show that there is both a “subjectal” and a “predicative” variety of vagueness, and that Peirce construes predicative vagueness according to three distinct models. Finally, we assess in what sense, i.e., according to which of the three models, common sense beliefs may be said to be invariably vague.