Roderick Milton Chisholm (/ˈtʃɪzəm/; November 27, 1916 – January 19, 1999) was an American philosopher known for his work on epistemology, metaphysics, free will, value theory, and the philosophy of perception. He received his Ph.D. at Harvard University under Clarence Irving Lewis and Donald C. Williams, and taught at Brown University. He served as president of the Metaphysical Society of America in 1973 and was often called "the philosopher's philosopher."