7 ideas
14626 | In S5 matters of possibility and necessity are non-contingent [Williamson] |
10594 | Henkin semantics is more plausible for plural logic than for second-order logic [Maddy] |
14625 | Necessity is counterfactually implied by its negation; possibility does not counterfactually imply its negation [Williamson] |
14623 | Strict conditionals imply counterfactual conditionals: □(A⊃B)⊃(A□→B) [Williamson] |
14624 | Counterfactual conditionals transmit possibility: (A□→B)⊃(◊A⊃◊B) [Williamson] |
14531 | Rather than define counterfactuals using necessity, maybe necessity is a special case of counterfactuals [Williamson, by Hale/Hoffmann,A] |
14628 | Imagination is important, in evaluating possibility and necessity, via counterfactuals [Williamson] |