Single Idea 3306

[catalogued under 12. Knowledge Sources / A. A Priori Knowledge / 1. Nature of the A Priori]

Full Idea

One proves non-existence (e.g. of round squares) by using logic to derive a contradiction from the concept; it is precisely here, in such proofs, that we find the clearest example of a priori knowledge.

Gist of Idea

The clearest a priori knowledge is proving non-existence through contradiction

Source

José A. Benardete (Metaphysics: the logical approach [1989], Ch. 4)

Book Reference

Benardete,José A.: 'Metaphysics: The Logical Approach' [OUP 1989], p.20

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