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Single Idea 16952

[from 'Could There Be Unicorns?' by Michael Dummett, in 4. Formal Logic / D. Modal Logic ML / 3. Modal Logic Systems / a. Systems of modal logic ]

Full Idea

If T is only possible if S obtains, and S is possible but doesn't obtain, then T is only possible in the world where S obtains, but T is not possible in the actual world. It follows that the relation of relative possibility is not transitive.

Gist of Idea

If something is only possible relative to another possibility, the possibility relation is not transitive

Source

Michael Dummett (Could There Be Unicorns? [1983], 1)

Book Reference

Dummett,Michael: 'The Seas of Language' [OUP 1993], p.330


A Reaction

[compressed]

Related Idea

Idea 16953 Relative possibility one way may be impossible coming back, so it isn't symmetrical [Dummett]