Roderick Milton Chisholm is widely regarded as one of the most creative, productive, and influential American philosophers of the 20th Century. Chisholm worked in epistemology, metaphysics, ethics, philosophy of language, philosophy of mind, and other areas. His work constitutes a grand philosophical system somewhat in the manner of Leibniz or Descartes. Chisholm continually refined — and sometimes utterly revised — his views. He was a prolific writer. The bibliography of his written work in [LLP] contains citations of 320 items, including journal articles, reviews, and books. His work in epistemology alone would probably guarantee his position as an outstanding figure in American philosophy. Yet he made major contributions in several areas of metaphysics and ethics as well.