Ideas from 'Modal Logic within Counterfactual Logic' by Timothy Williamson [2010], by Theme Structure

[found in 'Modality' (ed/tr Hale,B/Hoffman,A) [OUP 2010,]].

green numbers give full details    |     back to texts     |     expand these ideas

---

4. Formal Logic / D. Modal Logic ML / 3. Modal Logic Systems / h. System S5

14626

In S5 matters of possibility and necessity are non-contingent

10. Modality / A. Necessity / 1. Types of Modality

14625

Necessity is counterfactually implied by its negation; possibility does not counterfactually imply its negation

10. Modality / B. Possibility / 8. Conditionals / a. Conditionals

14623

Strict conditionals imply counterfactual conditionals: □(A⊃B)⊃(A□→B)

10. Modality / B. Possibility / 9. Counterfactuals

14624

Counterfactual conditionals transmit possibility: (A□→B)⊃(◊A⊃◊B)

10. Modality / C. Sources of Modality / 1. Sources of Necessity

14531

Rather than define counterfactuals using necessity, maybe necessity is a special case of counterfactuals [Hale/Hoffmann,A]

15. Nature of Minds / C. Capacities of Minds / 2. Imagination

14628

Imagination is important, in evaluating possibility and necessity, via counterfactuals