Single Idea 16960

[catalogued under 4. Formal Logic / D. Modal Logic ML / 3. Modal Logic Systems / d. System T]

Full Idea

If some world is 'a way the world might be considered to be if things were different in a certain respect', that might show that the accessibility relation should not be taken to be transitive, and we should have to adopt modal logic T.

Gist of Idea

If possibilitiy is relative, that might make accessibility non-transitive, and T the correct system

Source

Michael Dummett (Could There Be Unicorns? [1983], 8)

Book Reference

Dummett,Michael: 'The Seas of Language' [OUP 1993], p.348


A Reaction

He has already rejected symmetry from the relation, for reasons concerning relative identity. He is torn between T and S4, but rejects S5, and opts not to discuss it.