Richard Vulich (University of California Irvine)
"Frege’s Sharpness Requirement and Natural Language"
Controversy exists concerning the consequences of Frege’s sharpness requirement for concepts and functions. Some say that the sharpness requirement, if taken to be a necessary condition for truth functional language use, renders most of our natural language discourse meaningless. This is because most if not all natural language concepts and predicates are not sharp. In this essay I argue first that Frege does indeed see the sharpness requirement as a necessary condition on a language’s truth-functionality in all contexts in which language is used, and that the attempt to eschew the difficulty that this requirement presents by stipulating within a metalanguage what the extensions of our natural language concepts and predicates shall be is fundamentally at odds with Frege’s conception of logic. I then turn to a possible application of Frege’s notion of sharpness as a set of metaphysical presuppositions underlying the everyday use of concepts in contexts in which truth is being addressed.