David Lewis

David Lewis was a prominent philosopher known for his work on possible worlds, which posits that every way a situation could have been corresponds to a real, though perhaps unobservable, world. His ideas challenge traditional notions of modality—what could be or must be—by suggesting that these possibilities are just as real as our actual world. In ontology, he argued for a "realist" view of universals and properties. Additionally, Lewis contributed to the philosophy of time, advocating for a view where all points in time are equally real, akin to his theory of possible worlds, which has influenced metaphysics and the philosophy of science significantly.