William James, brother of Henry James, was a philosopher and psychologist born in New York City. He studied in Europe and earned his medical degree from Harvard University in 1869. He never practiced medicine, partially due to ill health and depression, but in 1872 he joined the Harvard faculty, where he taught first physiology and then psychology. At Harvard he also founded America's first psychology laboratory and, after twelve years, published the Principles of Psychology.

He sought to reconcile empirical, philosophical, and religious ideas through his theory of "pragmatism". This theory held that truth is relative and depends on its effect on human freedom. His well-known "Varieties of Relgious Experience" addressed the psychological aspects of religion. James dealt with basic human issues, which made him a central figure in American thought.