William James is considered by many to be the most insightful and stimulating of American philosophers, as well as the second of the three great pragmatists (the middle link between Charles Sanders Peirce and John Dewey). As a professor of psychology and of philosophy at Harvard University, he became the most famous living American psychologist and later the most famous living American philosopher of his time. Avoiding the logically tight systems typical of European rationalists, such as the German idealists, he cobbled together a psychology rich in philosophical implications and a philosophy enriched by his psychological expertise. More specifically, his theory of the self and his view of human belief as oriented towards conscious action raised issues that required him to turn to philosophy. There he developed his pragmatic epistemology, which considers the meaning of ideas and the truth of beliefs not abstractly, but in terms of the practical difference they can make in people’s lives. He explored the implications of this theory in areas of religious belief, metaphysics, human freedom and moral values, and social philosophy. His contributions in these areas included critiques of long-standing philosophical positions on such issues as freedom vs. determinism, correspondence vs. coherence, and dualism vs. materialism, as well as a thorough analysis of a phenomenological understanding of the self and consciousness, a “forward-looking” conception of truth (based on validation and revisable experience), a thorough-going metaphysical pluralism, and a commitment to a full view of agency in connection with communal and social concerns. Thus he created one of the last great philosophical systems in Western thought, even if he did not live quite long enough to complete every aspect of it. The combination of his provocative ideas and his engaging writing style has contributed to the enduring impact of his work.