Values and Imperatives

C. I. Lewis ranks among the most influential American academic philosophers. He spent most of his long career at Harvard University, guiding the education of many graduate students who later held faculty positions at American colleges and universities. As a very young professor, first at the University of California, at Berkeley and later at Harvard, Lewis established a national and international reputation in symbolic logic, to which he had been introduced in the early years of the century by his mentor Josiah Royce. Lewis wrote one of the early histories of symbolic logic, A Survey of Symbolic Logic (1918). Of more importance his dissatisfaction with the principle of material implication presented by Bertrand Russell and Alfred North Whitehead in Principia Mathematica inspired him to construct a system of strict implication, one of the earliest forms of modal logic. He presented this theory in a book he coauthored with Cooper Harold Langford, Symbolic Logic (1932).

Lewis is most famous for his articulation of a form of pragmatism known as conceptual pragmatism. A close student of Immanuel Kant, he was impressed with the role of a priori concepts in the interpretation of experience and the formation of knowledge. Critical of what he regarded as the neglect of formal conceptual structures by such philosophers as William James and John Dewey he upheld a doctrine of the a priori, but, unlike Kant, he stressed its pragmatic character. His epistemology of conceptual pragmatism was unfolded in his book Mind and the World-Order (1929).

When the American Philosophical Association met in 1945 for the first time after World War II, Lewis was invited to deliver its most prestigious lectures---the Paul Carus lectures. He addressed himself to the epistemological and valuational issues raised by the rising tide of logical positivism. He defended and elaborated a theory of meaning that denied its reducibility to the syntax of language. He drew sharp distinctio