William James was a philosopher and psychologist but was most well known in the field of Psychology for developing the philosophy of pragmatism, or the Functionalist theory: "Theory of mental life and behavior that is concerned with how an organism uses its perceptual abilities to function in its environment." He was also the first Psychologist to be born in America.

             William James was born on January 11, 1842 in New York City. His father, Henry James Sr. was a Swednborgian theologian, and one of his brothers was the great novelist Henry James. Throughout his youth, William attended private schools in the United States and Europe. He later attended the Lawrence Scientific School at Harvard University and then Harvard Medical School, where he received his degree in 1869 in the field of Physiology. The way that William got into the field of Psychology was that he got his degree in physiology and also enjoyed studying philosophy in his spare time, in psychology, he found, linked the two together. Before finishing his medical studies, he went on an exploring expedition in Brazil with the Swiss-American naturalist Louis Agassiz and also studied psychology in Germany. During this time, William retired due to illness but that didn"t stop his from excelling in the field. Three years later, in 1872, at the age of thirty, William become an instructor in physiology at Harvard University. In 1875, William started teaching Psychology at Harvard and after 1880 he was teaching both classes. .

             He taught at Harvard for thirty-five years, during which time; he wrote his first (and only) book; had his essays and lectures published in three different books: The Will to Believe and Other Essays in Popular Philosophy (1897), Human Immortality (1898), and The Varieties of Religious Experience (1902); and wrote a sympathetic psychological account of religious and mystical experiences, which was William"s last-named work.