Lewis was born on 28 September 1941 in Oberlin, Ohio, to a Professor of Government at Oberlin College and a distinguished medieval historian. He was known later in life for his formidable (even intimidating) intellect; this intelligence was already manifest during his years at Oberlin High School, when he attended college lectures in chemistry. He went on to Swarthmore College, and spent a year at Oxford (1959-1960), where he was tutored by Iris Murdoch and attended lectures by Gilbert Ryle, H. P. Grice, P. F. Strawson, and J. L. Austin. It was his year at Oxford that played a seminal role in his decision to study philosophy, and which made him the quintessentially Analytic philosopher that he would be for the rest of his life. Lewis went on to study at Harvard, where he studied with W. V. O. Quine.
His most important works include Convention (1969), which used concepts of game theory to analyze the nature of linguistic conventions; Counterfactuals (1973), which astonished the philosophical world with a ground-breaking analysis of counterfactual conditionals in terms of the theory of possible worlds; and On the Plurality of Worlds (1986), which fleshed out and defended the theory of modal realism which he had advanced in Counterfactuals.
Lewis suffered from severe diabetes for most of his life, which toward the end of his eventually grew worse and led into kidney failure. In July of 2000 he received a kidney transplant from his wife Stephanie. The transplant allowed him to work and travel for another year, before he died suddenly, and unexpectedly, from further complications of his diabetes, on 14 October 2001.