C.I. Lewis (1883–1964) was the most Kantian of all the pragmatists, although he did not become a pragmatist until he read Charles Sanders Peirce’s (1839–1914) papers, when he was given an office in the library room where they were stored at Harvard.

Lewis was born in Stoneharn, Massachusetts. His father was a shoe maker who became barred from employment due to union activism. Lewis attended Harvard as an undergraduate and returned to get his Ph.D. there after teaching in Colorado. He then went through the tenure process at the University of California and became well known for his work in symbolic logic. But he gave up his position as associate professor there to be an assistant professor in the Harvard department of philosophy in 1920, where he remained until 1953, serving twice as chair.

Lewis was the most famous philosopher of his generation during the 1940s, but he had become obscure by the 1960s, largely due to the success of his student W.V.O. Quine (1908–2000). Quine’s success was largely based on the widespread acceptance of his refutation of the analytic/synthetic distinction, which was the cornerstone of Lewis’ entire philosophical edifice. Lewis’ main works are A Survey of Symbolic Logic (1918); Symbolic Logic (1932), which was written with C.H. Lanford; Mind and the World Order (1929); An Analysis of Knowledge and Valuation (1946); and The Ground and Nature of the Right (1965).