Abstract: This discussion of Peirce's account of vagueness begins with a comparison of the attitudes towards vagueness of Frege, Peirce, and Wittgenstein. It explores Peirce's account of vagueness through an exploration of his account of assertion and his semiotic account of quantification in natural languages. The place of bivalence in his philosophy is discussed, as are his claims about the importance of vagueness for science and other kinds of cognition.

Keywords: assertion, bivalence, Frege, Peirce, quantification, science, vagueness, Wittgenstein,