Charles Sanders Peirce (10 September 1839 – 19 April 1914) was an American philosopher, logician, mathematician, and scientist who is regarded as the founder of pragmatism and one of the most original thinkers in American history. Bertrand Russell called him “one of the most original minds of the later nineteenth century and certainly the greatest American thinker ever.”
Born in Cambridge, Massachusetts, to the distinguished mathematician Benjamin Peirce, Charles graduated from Harvard College in 1859 and received a degree in chemistry summa cum laude from Harvard’s Lawrence Scientific School in 1863. For 32 years he practiced geodesy and chemistry for the U.S. Coast and Geodetic Survey while pursuing an immense range of research and writing. His nearest approach to an academic position was a lectureship in logic at Johns Hopkins University from 1879 to 1884.
In 1872, Peirce founded the Metaphysical Club with future Supreme Court Justice Oliver Wendell Holmes Jr. and philosopher William James, birthing the pragmatist movement. Peirce’s pragmatism holds that for any statement to be meaningful, it must have practical bearings—a method for clearing up metaphysics and aiding scientific inquiry. He later renamed his version “pragmaticism” to distinguish it from interpretations by James and Dewey.
Peirce made foundational contributions to logic, including the logic of relations, quantification theory, and threevalued logic. He identified logic in its widest sense with semiotics—the general theory of signs—arguing that “all this universe is perfused with signs, if it is not composed exclusively of signs.” His work on abduction (inference to the best explanation) alongside deduction and induction remains influential in philosophy of science. The Peirce papers at Harvard comprise an estimated 100,000 pages, testimony to the scope of a mind that transformed multiple fields.