Roderick Milton Chisholm (/ˈtʃɪzəm/; November 27, 1916 – January 19, 1999)[5] was an American philosopher known for his work on epistemology, metaphysics, free will, value theory, deontology, deontic logic and the philosophy of perception.

Richard and Fred Feldman, writing in the Stanford Encyclopedia of Philosophy, remark that he "is widely regarded as one of the most creative, productive, and influential American philosophers of the 20th Century.

He was drafted into the United States Army in July 1942 and did basic training at Fort McClellan in Alabama.

[7] He spent his academic career at Brown University and served as president of the Metaphysical Society of America in 1973.

Chisholm trained many distinguished philosophers, including Selmer Bringsjord, Fred Feldman, Keith Lehrer, James Francis Ross, Richard Taylor, and Dean Zimmerman.

Chisholm 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.

He argued that free will is incompatible with determinism, and believed that we do act freely; this combination of views is known as libertarianism.

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.

"While intended as a joke, the term has found some use in serious philosophical papers (for example, Kevin Meeker's "Chisholming away at Plantinga's critique of epistemic deontology").

In a strict philosophical sense, we must say that everyday vulgar objects do not persist through even the slightest change of parts.

If we consider these objects carefully, they are better understood as merely feigning identity, what Chisholm calls "ontological parasites" or ens per alio.

We may innocently discuss much of the world around us as persisting through change in the loose sense, but when we consider strict philosophical puzzles, we must not be fooled by ontological parasites.

Persons, unlike everyday vulgar material objects like ships and tables, persist in the strict and philosophical sense, even when they change their parts.