Clarence Irving Lewis

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Lewis, Clarence Irving


Born Apr. 12, 1883, in Stoneham, Mass.; died Feb. 3, 1964, in Menlo Park, Calif. American logician.

Lewis was appointed a professor of philosophy at Harvard University in 1930. His logical studies are chiefly concerned with the development of modal logic and its application for formalizing logical inference; he also studied problems arising in logical semantics. In 1912, Lewis demonstrated the difference between material implication and the ordinary concept of logical inference, and introduced the concept of strict implication based on the modal concept of possibility. Lewis developed a number of calculi for strict implication. Lewis’ philosophical ideas are closely related to pragmatism.


“Implication and the Algebra of Logic.” Mind, new series, vol. 21, no. 84, 1912.
A Survey of Symbolic Logic. Berkeley, 1918.


The Philosophy of C I. Lewis. London, 1968.