Ralph Barton Perry (1876-1957) was an American philosopher.
Perry argued for a naturalistic theory of value and a New Realist theory of perception and knowledge. He wrote a celebrated biography of William James, and proceeded to a revision of his critical approach to natural knowledge. An active member among a group of American New Realist philosophers, he elaborated around 1910 the program of new realism. However, he soon dissented from moral and spiritual ontology, and turned to a philosophy of disillusionment. Perry was an advocate of a militant democracy: in his words "total but not totalitarian".
- The Hope for Immortality, (1935)
- The Thought and Character of William James, (1935), Little, Brown, and Company, 1996 Vanderbilt University Press, paperback: ISBN 0-8265-1279-8
- The Thought and Character of William James As Revealed in Unpublished Correspondence and Notes Together With His Published Writings, Greenwood Publishing Group, hardcover reprint, ISBN 0-8371-7520-8