Fuzzy logic extends deductive methods to situations in which the information available may be only
partly or approximately true. Fuzzy logic has often been championed as a logic of vague terms, and it
does indeed provide an intuitive analysis of what goes wrong in Sorites reasoning. Here a fuzzy
semantics is given for a language containing the quasi-modal operators 'Determinately' (Î) and
'Indeterminately' (Ú). The semantics is sensitive to higher-order vagueness. For example, the
semantics distinguishes between Herbert's being a clear borderline case of a bald man and his being a
borderline borderline case of a bald man. I show that a famous reductio ad absurdum of the statement
'Ú(a=b)', due to Gareth Evans, is not valid when the background logic is fuzzy logic. Moreover, an
improved form of Evans's reductio due to Harold Noonan is also not valid.