more on this theme     |     more from this thinker

---

Single Idea 9470

[filed under theme 4. Formal Logic / D. Modal Logic ML / 4. Alethic Modal Logic ]

Full Idea

Modal logic is not an extensional language.

Gist of Idea

Modal logic is not an extensional language

Source

Charles Parsons (A Plea for Substitutional Quantification [1971], p.159 n8)

Book Ref

'Philosophy of Logic: an anthology', ed/tr. Jacquette,Dale [Blackwell 2002], p.159

---

A Reaction

[I record this for investigation. Possible worlds seem to contain objects]

---

The 3 ideas from 'A Plea for Substitutional Quantification'

9469	Substitutional existential quantifier may explain the existence of linguistic entities [Parsons,C]

9468	On the substitutional interpretation, '(∃x) Fx' is true iff a closed term 't' makes Ft true [Parsons,C]

9470	Modal logic is not an extensional language [Parsons,C]