Single Idea 16958

[catalogued under 4. Formal Logic / D. Modal Logic ML / 3. Modal Logic Systems / g. System S4]

Full Idea

In S4 logic the actual world is, in itself, special, not just from our point of view.

Gist of Idea

In S4 the actual world has a special place

Source

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

Book Reference

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


A Reaction

S4 lacks symmetricality, so 'you can get there, but you can't get back', which makes the starting point special. So if you think the actual world has a special place in modal metaphysics, you must reject S5?