(1883 - 1964 )
One of the few and upcoming American philosophers. Lewis went on to Harvard to get both a Bachelors and a Phd. He then went on to teach at the University of California, and served as professor of philosophy at Harvard until he retired, as emeritus.
His chief importance is a philosopher who made progress in combining symbolic logic with pragmatic epistemology. To do this he had to come up with his own version of logic, in opposition to the one made by the towering giant in the field at the time, the noted and revered Bertrand Russell. Who, if you'll recall sent a rather devastating letter to Frege.
Anyway, Lewis argues that the choice between philosophical systems (in particular those pertaining to logic) should be made pragmatically, rather than being tied to a particular ideal. In this respect he wasn't a million miles from Nietzsche.
His works include: A Survey of Symbolic Logic (1918), Mind and the World-Order (1929),
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).