Roderick Milton Chisholm (November 27, 1916 – January 19, 1999) was an American philosopher known for his work on epistemology, metaphysics, free will, 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.
Chisholm graduated from Brown University in 1938 and got his Ph.D. from Harvard University in June 1942. He was drafted into the United States Army in July 1942 and did basic training at Fort McClellan in Alabama. Chisholm administered psychological tests in Boston and New Haven. In 1943 he married Eleanor Parker, whom he had met as an undergraduate at Brown.
Chisholm's first major work was Perceiving (1957). His epistemological views were summed up in a popular text, Theory of Knowledge, which appeared in three very different editions (1966, 1977, and 1989). His masterwork was Person and Object, its title deliberately contrasting with W. V. O. Quine's Word and Object. Chisholm was a metaphysical Platonist in the tradition of Bertrand Russell, and a rationalist in the tradition of Russell, G. E. Moore, and Franz Brentano; he objected to Quine's anti-realism, behaviorism, and relativism. He defended the possibility of empirical knowledge by appeal to a priori epistemic principles whose consequences include that it is more reasonable to trust your senses and memory in most situations than to doubt them. His theory of knowledge was also famously "foundationalist" in character: all justified beliefs are either "directly evident" or supported by chains of justified beliefs that ultimately lead to beliefs that are directly evident. He also defended a controversial theory of volition called "agent causation" much like that of Thomas Reid. He argued that free will is incompatible with determinism, and believed that we do act freely; this combination of views is known as libertarianism. He developed a highly original theory of first person thought according to which the things we believe are properties, and believing them is a matter of self-attributing them. (A similar view was developed independently by David Kellogg Lewis, and enjoys considerable popularity, although it is now known mainly through Lewis's work.) Chisholm was also famous for defending the possibility of robust self-knowledge (against the skeptical arguments of David Hume), and an objective ethics of requirements similar to that of W. D. Ross. Chisholm's other books include The Problem of the Criterion, Perceiving, "The First Person" and A Realist Theory of the Categories, though his numerous journal articles are probably better known than any of these.
Chisholm read widely in the history of philosophy, and frequently referred to the work of Ancient, Medieval, Modern, and even Continental philosophers (although the use he made of this material has sometimes been challenged). Nonetheless, he greatly respected the history of philosophy, in the face of a prevailing indifference among analytic philosophers. Chisholm translated some work by Brentano and by Husserl, and contributed to the post-1970 renaissance of mereology.
Chisholm greatly influenced a number of his graduate students and colleagues, including Richard Taylor, Jaegwon Kim, Keith Lehrer, R. C. Sleigh, Ernest Sosa, Peter D. Klein, Fred Feldman, Terence Penelhum, Selmer Bringsjord, Dean Zimmerman, David Benfield, Joseph Boyle and Bernard K. Symonds.