Single Idea 9775

[catalogued under 5. Theory of Logic / D. Assumptions for Logic / 2. Excluded Middle]

Full Idea

Maybe classical logic fails for vagueness in Excluded Middle. If 'H bald ∨ ¬(H bald)' is true, then one disjunct is true. But if the second is true the first is false, and the sentence is either true or false, contrary to the borderline assumption.

Gist of Idea

Excluded Middle, and classical logic, may fail for vague predicates

Source

Kit Fine (Vagueness, Truth and Logic [1975], 4)

Book Reference

'Vagueness: a Reader', ed/tr. Keefe,R /Smith,P [MIT 1999], p.137


A Reaction

Fine goes on to argue against the implication that we need a special logic for vague predicates.