At the turn of the twentieth century, William James was America's most widely read philosopher. In addition to being one of the founders of pragmatism, however, he was also a leading psychologist and author of the seminal work, The Principles of Psychology (1890). While scholars argue that James withdrew from the study of psychology after 1890, Eugene Taylor demonstrates convincingly that James remained preeminently a psychologist until his death in 1910.

Taylor details James's contributions to experimental psychopathology, psychical research, and the psychology of religion. Moreover, Taylor's work shows that out of his scientific study of consciousness, James formulated a sophisticated metaphysics of radical empiricism.

In light of historical developments in psychology, as well as the current philosophic implications of the neuroscience revolution as it is related to the biology of consciousness, Taylor argues that both the subject matter of James's investigations and his metaphysics of radical empiricism are just as important for psychology today as James believed they were in his own time.