A major American thinker who made lasting contributions to both psychology and philosophy, James was born in New York City in 1842. His highly cultured family included his father, the religious philosopher Henry James Sr., and his brother, the novelist Henry James. James received a varied education at home and in Europe, eventually attending Harvard University to study science and medicine. His poor health prevented him from practicing medicine, however, so he instead devoured books on psychology and religion which would ignite his future intellectual interests. 

In 1872, James became an instructor in physiology at Harvard, and then switched to teaching psychology. He was a pioneer in this field, transforming the study of the mind from a branch of philosophy to a laboratory science; he is often considered “the father of American psychology” (Ehrenfeld, Temma. "How William James encourages us to believe in the possible.” Encyclopedia Britannica.). James’s marriage to Alice Gibbens in 1878 complemented what was generally a happy period of his life. However, James was not satisfied to stay in the psychological laboratory permanently, and instead gravitated toward the study of religious and philosophical questions.

James examined such questions as free will, determinism, life after death, and the existence of God, using his background in scientific research to shed light on these topics in the essay collection The Will to Believe (1896).