Abstract

A theory of vagueness must lie at the heart of any complete theory of meaning. This chapter offers a theory of vagueness, and of indeterminacy generally, since the indeterminacy of vague borderline proposition is only one source of indeterminacy. The theory distinguishes two kinds of partial belief: standard partial belief, which is normatively governed by the axioms of probability theory, and what I call vagueness-related partial belief, which is not normatively governed by those axioms. Thanks to the pleonastic nature of properties, it is possible to define vagueness and indeterminacy in terms of vagueness-related partial belief. The account of vagueness is applied to the sorites paradox, and resolving that paradox requires distinguishing between what I call happy-face and unhappy-face solutions to a paradox. The theory of indeterminacy yields a resolution of Gareth Evans’s puzzle about indeterminate identity.