The epistemicist solution to the Sorites Paradox consists of two key components. First, vague terms, just as non-vague ones, have ordinary classical semantic-values and do not require any revision of classical logic or semantics. In the case of ‘tall’, each person is either tall or not tall, and there is a specific number k such that someone is tall if and only if they are over k metres in height, thus ensuring that one of the premises of the paradox is just plainly false. Second, although words like ‘tall’ have such sharp boundaries, we do not and cannot know what these boundaries are, and this explains why we might be tempted to (falsely) conclude that such boundaries do not exist.

Epistemicm faces four principle challenges: addressing the counterintuitiveness of the view; accounting for how the sharp meanings of vague terms are determined; explaining why we are principally ignorant of the sharp-boundaries of vague terms; and explaining what makes vagueness into a distinctive phenomenon, different than other kinds of ignorance. The chapter focuses on discussion of these four challenges, presents the most prominent defence of Epistemicism - Timothy Williamson’s- and discusses a range of objections from recent literature to these responses.

Take any putative ordinary object which is divisible into a finite number of small units and tolerant to the loss of one of them. We can remove these units one at a time, and since our object definitely doesn’t exist when there are zero units, and since we cannot pinpoint which removal brings about this destruction,the Sorites Puzzle threatens common sense. We can rescue ordinary objects from its grip, but since independently motivated linguistic explanations of vagueness depend on there being multiple candidate contents of vague terms, these efforts succeed only if there are multiple candidates that can be meant by ordinary object terms. Thus, many more objects than common sense accepts have to exist. The 'arguments from vagueness' also offer soritical reasons for object proliferation. Problematising the categories composite object and persisting thing (rather than specific object concepts), these show that either there are none of these (except simples) or every candidate for making up one, does. The latter, less revisionary alternative is plenitudinism. I defend Modally Full Plenitude, because it is three-dimensionalist and non-reductivist about de re modality – a distinct persisting object in any region, and for every modal profile satisfied by the matter in that region.

The vagueness-intuitionist credits epistemicism with a crucial insight, namely that vagueness is a cognitive, rather than a semantic phenomenon: the vagueness of the distinction between, say, yellow and orange consists in our inability to, so to speak, bring those two concepts up against one another to mark a sharp and stable boundary. The chapter proposes a knowledge-theoretic semantics for a first-order logic of vagueness that respects this conception of the nature of the phenomenon. The semantics diverges from traditional intuitionist-style semantics (Heyting, Beth, Kripke) in the treatment of negation, taking the idea of incompatibility between atomic vague predications as primitive, and setting the negation of atomic A as acceptable just when some statement is acceptable which is incompatible with A. It is shown how a semantics based on this idea vindicates an intuitionist-style repudiation of the principle of Bivalence and thereby the law of excluded middle, and thus enables the reasoning of the Sorites Paradox to go through as a demonstration of the negation of its major premisewithout thereby incurring the unwelcome implication, sustained by classical logic, of the existence of a sharp boundary to the extension of the relevant predicate.