講師 Nicholas J.J. Smith (Associate Professor, University of Sidney)
日時 11月１日（金）16:30- 18:00
題目 Fuzzy Logic and Higher-Order Vagueness
The major reason given in the philosophical literature for dissatisfaction with theories of vagueness based on fuzzy logic is that such theories give rise to a problem of `higher-order vagueness’ or `artificial precision’. In this talk I first outline the problem and survey suggested solutions: fuzzy epistemicism; measuring truth on an ordinal scale; logic as modelling; a hierarchy of fuzzy metalanguages; truth values with an internal hierarchical structure (blurry sets); and fuzzy plurivaluationism. I then argue that in order to decide upon a solution, we need to understand the true source of the problem. Two possible sources are discussed: the problem stems from the very nature of vagueness (i.e. from the defining features of vague predicates); or the problem stems from the way in which the meanings of predicates are determined (by the usage of speakers together with facts about their environment and so on). I argue that the latter is the true source of the problem — and on this basis, that fuzzy plurivaluationism is the correct solution.