David Kellogg Lewis (September 28, 1941 – October 14, 2001) 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 has made contributions in
philosophy of language,
philosophy of mind,
metaphysics,
epistemology, and
philosophical logic. He is probably best known for his controversial
modal realist stance: that (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, and (iv) our world is among the possible worlds.