Single Idea 9388

[catalogued under 9. Objects / B. Unity of Objects / 3. Unity Problems / e. Vague objects]

Full Idea

Of any concept, we must require that it have a sharp boundary. Of any object it must hold either that it falls under the concept or it does not. We may not allow a third case in which it is somehow indeterminate whether an object falls under a concept.

Gist of Idea

Every concept must have a sharp boundary; we cannot allow an indeterminate third case

Source

Gottlob Frege (Logic in Mathematics [1914], p.229), quoted by Ian Rumfitt - The Logic of Boundaryless Concepts p.1 n1


A Reaction

This is the voice of the classical logician, which has echoed by Russell. I'm with them, I think, in the sense that logic can only work with precise concepts. The jury is still out. Maybe we can 'precisify', without achieving total precision.