Single Idea 14453

[catalogued under 4. Formal Logic / A. Syllogistic Logic / 2. Syllogistic Logic]

Full Idea

Some moods of the syllogism are fallacious, e.g. 'Darapti': 'All M is S, all M is P, therefore some S is P', which fails if there is no M.

Gist of Idea

The Darapti syllogism is fallacious: All M is S, all M is P, so some S is P' - but if there is no M?

Source

Bertrand Russell (Introduction to Mathematical Philosophy [1919], XV)

Book Reference

Russell,Bertrand: 'Introduction to Mathematical Philosophy' [George Allen and Unwin 1975], p.164


A Reaction

This critique rests on the fact that the existential quantifier entails some existence, but the universal quantifier does not.

Related Idea

Idea 13819 Aristotle's said some Fs are G or some Fs are not G, forgetting that there might be no Fs [Bostock on Aristotle]