What Vagueness Consists In

The main question of the paper is that ofwhat vagueness consists in. This question must be distinguished from other questions about vagueness discussed in the literature. It is argued that familiar accounts of vagueness for general reasons failto answer the question ofwhat vagueness consists in. A positive view is defended, according to which, roughly, the vagueness of an expression consists in it being part ofsemantic competence to accept a tolerance principle for the expression. Since tolerance principles are inconsistent, this is an inconsistency view on vagueness.Manythanks to Ólafur PállJónsson, Peter Koellner, Agustín Rayo, audiences at Yale University and the University of Colorado at Boulder, and to Kent Bach and John MacFarlane and other members ofthe Bay Area Philosophy of Language Reading Group, for helpful comments on this paper (and ancestors thereof).