Abstract

For all post-1970s effort expended on the topic, the most central and important question about vagueness—what it is: what, specifically, something’s being a borderline case of a vague expression consists in—has seldom been tackled with the theoretical explicitness necessary if issues expectably downstream of it, like the nature of valid inference among vague statements, or the Sorites paradox, are to receive a properly motivated treatment. The great interest of Chapter V of The Things We Mean is that it points the way towards a new kind of approach, according to which vagueness is constitutively a psychological phenomenon, grounded in the characteristic propositional attitudes of practitioners of vague discourse. It’s uncontroversial that a vague expression is one whose presence in a sentence contributes towards there being, at least in principle, situations which present borderline cases of its truth; for Schiffer, it is the status of such a situation as a borderline case that is grounded in the characteristic psychology of thinkers who appraise the sentence in that situation.