Lewis, Clarence Irving

Lewis, Clarence Irving, 1883–1964, American philosopher, b. Stoneham, Mass., grad. Harvard (B.A., 1906; Ph.D., 1910). After teaching (1911–20) at the Univ. of California, he was professor of philosophy at Harvard from 1920 to 1953, when he became professor emeritus. Lewis's importance as a philosopher lies in his combination of symbolic logic with an essentially pragmatic epistemology. After studying logic under Josiah Royce, he developed his own system of symbolic logic in opposition to the Principia Mathematica of Bertrand Russell and Alfred North Whitehead. However, he soon began investigations in the field of epistemology. In his main work, Mind and the World-Order (1929), he developed a position according to which the choice between logical (and thus philosophical) systems must be based on pragmatic grounds. His other works include A Survey of Symbolic Logic (1918), Symbolic Logic (with C. H. Langford, 1932), An Analysis of Knowledge and Valuation (1946), Our Social Inheritance (1957), and The Ground and Nature of the Right (1955).

Bibliography

See his Collected Papers, ed. by J. D. Goheen and J. L. Mothershead (1970); J. R. Saydah, The Ethical Theory of Clarence Irving Lewis (1969).

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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.

WORKS

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

REFERENCE

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