Card 1.6 · Root I — Metaphysics
Modality
What does it mean to say something could have been different?
Modality is the study of possibility and necessity — of what could have been otherwise, what could not, and what makes the difference.
Where it sits
Under I. Metaphysics. Contains 1.6.1 Possible worlds. Borders 1.7 Free will, 4.3 Modal logic, 1.2.2 Fine-tuning.
Narrower questions under this one:
The rival answers
| Position | What grounds possibility |
|---|---|
| Modal realism | Other possible worlds exist, as concretely as this one |
| Ersatzism | Possible worlds are abstract representations, not places |
| Modal fictionalism | Worlds talk is a useful fiction; the claims are literally false |
| Dispositionalism | Possibility is grounded in the powers actual things have |
| Conventionalism | Modal claims record our linguistic conventions |
Key figures
| Figure | Dates | Tradition | Contribution |
|---|---|---|---|
| Aristotle | 384–322 BCE | Greek | Potentiality and actuality; the sea battle problem |
| Ibn Sina | 980–1037 | Islamic | Necessary and contingent existence as a basic division |
| Duns Scotus | c. 1266–1308 | Scholastic | Synchronic possibility; alternatives at a single moment |
| G. W. Leibniz | 1646–1716 | European modern | Possible worlds as ideas in the divine mind |
| Saul Kripke | 1940–2022 | Analytic | Necessity distinguished from the a priori |
Connections
→ 1.1, 1.6.1 · ↔ 1.7, 4.3, 1.2.2, 6.10.1 · ◇ modal realism, ersatzism, fictionalism, dispositionalism · ○ Islamic golden age; Scholastic; Modern; Table 1
→ narrower questions · ↔ questions it borders · ◇ the positions, mapped in Part III of the book · ○ the eras and comparison tables (Parts IV and V)
The full card is in the book
In The Coordinates of Thought this card goes on to a worked example that sets the answers against one case, and to where the question touches daily life — page 66.
On Coordinates of Thought
Conversations about this question in Possibility & necessity:
- S5 is the right logic for metaphysical necessity 6 replies
- Reading group: David Lewis, On the Plurality of Worlds (1986), chapters 1–4 6 replies
- Reading group: Epictetus, Discourses II.19, where the Master Argument meets a bus driver 5 replies
- Possibility lives in the powers of real things, not in other worlds 5 replies
- The incredulous stare is a perfectly respectable argument against modal realism 5 replies
Join free to ask about it Everything in Possibility & necessity