Bob Hale: The Basis of Necessity and Possibility

Part of the Royal Institute of Philosophy's 2016 London Lecture series: Metaphysics.

This lecture argues that modal concepts should be explained in terms of the essences or nature of things: necessarily p if, and because, there is something the nature of which ensures that p; possibly p if, and because, there is nothing whose nature rules out its being true that p. The theory is defended against various objections and difficulties, including ones arising from attributing essences to contingent individuals.