more from Nathan Salmon

Single Idea 14691

[catalogued under 4. Formal Logic / D. Modal Logic ML / 3. Modal Logic Systems / h. System S5]

Full Idea

Believers in S5 as a correct system of propositional reasoning about what might have been must claim that it is an essential property of any way things might have been that things might have been that way.

Gist of Idea

S5 believers say that-things-might-have-been-that-way is essential to ways things might have been


Nathan Salmon (The Logic of What Might Have Been [1989], V)

Book Reference

Salmon,Nathan: 'Metaphysics, Mathematics and Meaning' [OUP 2005], p.145

A Reaction

Salmon is working in a view where you are probably safe to substitute 'necessary' for 'essential' without loss of meaning.