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Single Idea 11001

[catalogued under 10. Modality / A. Necessity / 2. Nature of Necessity]

Full Idea

The equation of 'necessity' with 'true in every possible world' is known as the S5 conception, corresponding to the strongest of C.I.Lewis's five modal systems.

Gist of Idea

Equating necessity with truth in every possible world is the S5 conception of necessity


Stephen Read (Thinking About Logic [1995], Ch.4)

Book Reference

Read,Stephen: 'Thinking About Logic' [OUP 1995], p.118

A Reaction

Are the worlds naturally, or metaphysically, or logically possible?