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.