David Lewis (philosopher)

David Kellogg Lewis was an American philosopher. Lewis taught briefly at UCLA and then at Princeton from 1970 until his death. He is also closely associated with Australia, whose philosophical community he visited almost annually for more than thirty years. He made contributions in philosophy of language, philosophy of mind, philosophy of probability, metaphysics, epistemology, philosophical logic, and aesthetics. He is probably best known for his controversial modal realist stance:
(i) Possible worlds exist.
(ii) Every possible world is a concrete entity.
(iii) Any possible world is causally and spatiotemporally isolated from any other possible world.
(iv) Our world is among the possible worlds.