David K. Lewis (philosopher)

David K. Lewis was a prominent philosopher known for his work in metaphysics and philosophy of language. He proposed that all possible worlds—ways reality could have been—are as real as the actual world we live in, a view called modal realism. This helps explain concepts like possibility, necessity, and counterfactuals (if-then statements that explore alternate scenarios). Lewis also contributed to understanding the nature of belief, causality, and identity. His ideas influence how philosophers think about the structure of reality and how we consider different hypothetical situations.