Williamson on Our Ignorance in Borderline Cases

Abstract

Timothy Williamson's instructive and ingenious Vagueness advances an epistemic theory of vagueness. This theory asserts that if a thing a borderline case of a property, then it's either a fact that the thing has the property or else a fact that it doesn't, but that in neither case can one know what the fact of the matter is. Williamson deft at criticizing competing theories, and he does a creditable job defending the principle of bivalence, which the primary motivation for the epistemic theory. But he recognizes that it will remain difficult to take the theory seriously without a compelling account of why we're doomed to ignorance in borderline cases. Consequently, the centerpiece of his book his attempt to give such an account. That attempt will be my present concern. In Vagueness, Williamson seeks to explain why we should be ignorant of the truth-values of vague utterances by showing that such ignorance is just what independently justified epistemic principles would lead one to expect (p. 215), where these principles, which govern cases of inexact knowledge, are what he calls margin-for-error principles. But it's possible to give his account of ignorance without mentioning inexact knowledge or margin-forerror principles, and in a recent article Williamson himself does just that.' I'll follow suit, restating what I take to be Williamson's account in my own words. Williamson recognizes that there no such thing as the property of being bald, for occurrences of 'bald' can express different properties in different contexts of utterance. Without any change in Harold, an utterance of 'Harold bald' might be true in one context and false in another. At the same time, Williamson holds that normal utterances of 'bald'-even when ascribed in borderline cases-express unique, determinate properties, and this permits us to ignore, for expository reasons, the context sensitivity of 'bald' and to pretend that 'Harold bald' determinately expresses the unique proposition that