David Lewis

David Kellogg Lewis was an American philosopher, born in 1941 and died in 2001, who taught briefly at UCLA before joining Princeton University in 1970, where he remained until his death. He was closely associated with the Australian philosophical community, which he visited almost annually for more than three decades. Lewis made significant contributions across philosophy of mind, philosophy of probability, epistemology, philosophical logic, aesthetics, philosophy of mathematics, philosophy of time and philosophy of science, and is considered among the most important figures in most of these fields in recent decades. He is best known for his work in metaphysics and philosophy of language, where his books Counterfactuals, published in 1973, and On the Plurality of Worlds, published in 1986, are considered classics; his account of counterfactual conditionals, developed alongside a competing account from Robert Stalnaker, became one of the most influential theories of its type in philosophy and linguistics. His metaphysics included seminal contributions to quantified modal logic, counterpart theory, counterfactual causation and the position called Humean supervenience, and in On the Plurality of Worlds he defended modal realism, the view that possible worlds exist as concrete entities and that the actual world is only one among many equally real possible worlds.