The Epistemic Conception of Vagueness

This chapter challenges Epistemicism. It rebuts Williamson’s arguments for unrestricted Bivalence, based on the Disquotational Scheme for the truth predicate, and Sorensen’s arguments that the idea of a predicate’s being of limited sensitivity is itself incoherent. The chapter nevertheless proposes a broadly epistemic conception of what a definite case of a vague predicate is—namely, a case where at least one of two conflicting verdicts about a vague predication must involve some kind of cognitive shortcoming, and proposes a corresponding notion of a borderline case—one where each of a pair of conflicting verdicts can be unexceptionable—and sides with Epistemicism in rejecting the idea of such cases as truth-value gaps. It is contended that Williamson’s explanation of why we cannot know where the putative sharp cut-offs in Sorites series come at best explains too little, since it has nothing plausible to say about our ignorance throughout a borderline area, nor about vagueness induced by deliberate approximation—‘roughly six feet tall’, ‘about a metre long’.

Vagueness and Intuitionistic Logic

This chapter considers the question: should we employ intuitionistic logic, not classical logic, when reasoning with vague concepts? In his commentary on Michael Dummett’s “Wang’s Paradox,” Crispin Wright presents an apparently powerful argument in favour of an affirmative answer to this question. This chapter advocates a less conclusive answer than Wright’s. It is argued that intuitionistic logic may be the strongest logic we are entitled to use in reasoning with any vague predicate, but there may also be common and central families of vague term where we are entitled to use classical logic.

Tolerance effect in categorisation with vague predicates

Vagueness is understood as the problem of associating imprecise application criteria with ordinary predicates such as ‘bald’ or ‘blue’. It is often construed as due to one’s tolerance to a minute difference in forming a verdict on the application of a vague predicate. This paper reports an experiment conducted to test the effect of tolerance, using as paradigm categorisation tasks performed with respect to transitional series, e.g., a series of tomatoes from red to orange. The findings suggest a negative effect of tolerance on categorisation with vague predicates. The implication of the findings for certain commonly-held assumptions about tolerance is discussed.

Stephen Clark, the Laws of Logic and the Sorites

A standard method for refuting a set of claims is to show that it implies a contradiction. Stephen Clark questions this method on the grounds that the Law of Non-Contradiction, together with the other fundamental laws of logic do not accord with everyday reality. He accounts for vagueness by suggesting that, for any vague predicate ‘F’, an ordinary object is typically to some extent both F and not-F, and that objects do not change abruptly from being F to being not-F. I challenge Clark's ‘deconstruction’ of logic, and show that, in characterizing vagueness and dealing with the associated Sorites paradox, we can accommodate his observation that change from being F to being not-F is ineradically continuous without tampering with any fundamental logical laws.