Vagueness - Related Attitudes

NYU Stephen Schiffer claims (in the present collection) that vagueness is essentially a psychological phenomenon. According to him, vagueness should not be explicated in terms of absent truth values or incurable ignorance—that is, as a semantic or an epistemic phenomenon—but rather in terms of a peculiar new type of propositional attitude. Schiffer introduces the notion of a vagueness-related partial belief and bases upon it both a novel analysis of the notion of a borderline case and a novel solution to the sorites paradox. He defines standard partial beliefs (SPBs) as partial beliefs which can under suitable idealization be identified with subjective probability (p. 221). He defines vagueness-related partial beliefs (VPBs) as partial beliefs which cannot be so identified (p. 223). He adds that VPBs, by contrast to SPBs, do not measure uncertainty or generate corresponding likelihood beliefs (p. 223). He defines a paradigm VPB (VPB*) as a VPB held by an ideally rational thinker who knows, with certainty, that she is in ideal epistemic conditions with respect to the content of her VPB (p. 227). Schiffer then analyzes the notion of a borderline case as follows: x is to some extent a borderline case of being F just in case someone could have a VPB* that x is F. Near the end of his paper, Schiffer suggests the possibility of reformulating his analysis in