Advanced · a field of logic
Modal Logic
Necessity and possibility, made rigorous by Kripke’s possible-worlds semantics, with their kin: temporal, epistemic, and deontic logics.
- The problem
- How can “necessarily” and “possibly” be made precise enough to reason with, without collapsing into paradox?
- The turning point
- Kripke semantics: necessity is truth at every accessible world, and the modal systems map onto properties of accessibility.
- An open question
- What is the right modal logic for knowledge, obligation, and provability, and how do they interact?
The Canon
- Semantical Considerations on Modal Logic 1963
- Counterfactuals
To study it
- Modal Logic: An Introduction
- A New Introduction to Modal Logic
- Modal Logic