William James (January 11, 1842 – August 26, 1910) was a pioneering American psychologist and philosopher who was trained as a medical doctor. He wrote influential books on the young science of psychology, educational psychology, psychology of religious experience and mysticism, and on the philosophy of pragmatism. He was the brother of novelist Henry James and of diarist Alice James.

William James was born at the Astor House in New York City. He was the son of Henry James Sr., an independently wealthy and notoriously eccentric Swedenborgian theologian well acquainted with the literary and intellectual elites of his day. The intellectual brilliance of the James family milieu and the remarkable epistolary talents of several of its members have made them a subject of continuing interest to historians, biographers, and critics.

James interacted with a wide array of writers and scholars throughout his life, including his godfather Ralph Waldo Emerson, his godson William James Sidis, as well as Charles Sanders Peirce, Bertrand Russell, Josiah Royce, Ernst Mach, John Dewey, Walter Lippmann, Mark Twain, Horatio Alger, Jr., Henri Bergson and Sigmund Freud.

William James, with his younger brother Henry James (who became a prominent novelist) and sister Alice James (who is known for her posthumously published diary), received an eclectic trans-Atlantic education, developing fluency in both German and French. Education in the James household encouraged cosmopolitanism. The family made two trips to Europe while William James was still a child, setting a pattern that resulted in thirteen more European journeys during his life. His early artistic bent led to an apprenticeship in the studio of William Morris Hunt in Newport, Rhode Island, but he switched in 1861 to scientific studies at the Lawrence Scientific School of Harvard University.

In his early adulthood, James suffered from a variety of physical ailments, including those of the eyes, back, stomach, and skin. He was also tone deaf. He was subject to variety of psychological symptoms which were diagnosed at the time as neurasthenia, and which included periods of depression during which he contemplated suicide for months on end. Two younger brothers, Garth Wilkinson (Wilky) and Robertson (Bob), fought in the Civil War. The other three siblings (William, Henry, and Alice James) all suffered from periods of invalidism.

James took up medical studies at Harvard Medical School in 1864. He took a break in the spring of 1865 to join naturalist Louis Agassiz on a scientific expedition up the Amazon River, but aborted his trip after eight months, as he suffered bouts of severe seasickness and mild smallpox. His studies were interrupted once again due to illness in April 1867. He traveled to Germany in search of a cure and remained until November 1868. (During this period he began to publish, with reviews appearing in literary periodicals like the North American Review.) He finally earned his M.D. degree in June 1869, but never practiced medicine. What he called his "soul - sickness" would only be resolved in 1872, after an extended period of philosophical searching. He married Alice Gibbens in 1878.

James's time in Germany proved intellectually fertile, helping him find that his true interests lay not in medicine but in philosophy and psychology. Later, in 1902 he would write: "I originally studied medicine in order to be a physiologist, but I drifted into psychology and philosophy from a sort of fatality. I never had any philosophic instruction, the first lecture on psychology I ever heard being the first I ever gave".

James spent almost his entire academic career at Harvard. He was appointed instructor in physiology for the spring 1873 term, instructor in anatomy and physiology in 1873, assistant professor of psychology in 1876, assistant professor of philosophy in 1881, full professor in 1885, endowed chair in psychology in 1889, return to philosophy in 1897, and emeritus professor of philosophy in 1907.

James studied medicine, physiology, and biology, and began to teach in those subjects, but was drawn to the scientific study of the human mind at a time when psychology was constituting itself as a science. James's acquaintance with the work of figures like Hermann Helmholtz in Germany and Pierre Janet in France facilitated his introduction of courses in scientific psychology at Harvard University. He taught his first experimental psychology course at Harvard in the 1875 - 1876 academic year.

During his Harvard years, James joined in philosophical discussions with Charles Peirce, Oliver Wendell Holmes, and Chauncey Wright that evolved into a lively group informally known as The Metaphysical Club in 1872. Louis Menand speculates that the Club provided a foundation for American intellectual thought for decades to come.

Among James's students at Harvard University were such luminaries as Boris Sidis, Theodore Roosevelt, George Santayana, W.E.B. Du Bois, G. Stanley Hall, Ralph Barton Perry, Gertrude Stein, Horace Kallen, Morris Raphael Cohen, Walter Lippmann, Alain Locke, C.I. Lewis, and Mary Calkins.

Following his January, 1907 retirement from Harvard, James continued to write and lecture, publishing Pragmatism, A Pluralistic Universe, and The Meaning of Truth. James was increasingly afflicted with cardiac pain during his last years. It worsened in 1909 while he worked on a philosophy text (unfinished but posthumously published as Some Problems in Philosophy). He sailed to Europe in the spring of 1910 to take experimental treatments which proved unsuccessful, and returned home on August 18. His heart failed him on August 26, 1910 at his home in Chocorua, New Hampshire. He was buried in the family plot in Cambridge Cemetery, Cambridge, Massachusetts.

He was one of the strongest proponents of the school of functionalism in psychology and of pragmatism in philosophy. He was a founder of the American Society for Psychical Research, as well as a champion of alternative approaches to healing. He challenged his professional colleagues not to let a narrow mindset prevent an honest appraisal of those phenomena.

In an empirical study by Haggbloom et al. using six criteria such as citations and recognition, James was found to be the 14th most eminent psychologist of the 20th Century.

William James wrote voluminously throughout his life. A non-exhaustive bibliography of his writings, compiled by John McDermott, is 47 pages long.

He gained widespread recognition with his monumental Principles of Psychology (1890), totaling twelve hundred pages in two volumes, which took twelve years to complete. Psychology: The Briefer Course, was an 1892 abridgement designed as a less rigorous introduction to the field. These works criticized both the English associationist school and the Hegelianism of his day as competing dogmatisms of little explanatory value, and sought to re-conceive the human mind as inherently purposive and selective.

President Jimmy Carter's Moral Equivalent of War Speech, on April 17, 1977, equating the United States' 1970's energy crisis, oil crisis and the changes and sacrifices Carter's proposed plans would require with the "moral equivalent of war," may have borrowed its title, much of its theme and the memorable phrase from James' classic essay "The Moral Equivalent of War" derived from his last speech, delivered at Stanford University in 1906, in which "James considered one of the classic problems of politics: how to sustain political unity and civic virtue in the absence of war or a credible threat...." and "...sounds a rallying cry for service in the interests of the individual and the nation."

James defined true beliefs as those that prove useful to the believer. His pragmatic theory of truth was a synthesis of correspondence theory of truth and coherence theory of truth, with an added dimension. Truth is verifiable to the extent that thoughts and statements correspond with actual things, as well as the extent to which they "hang together," or cohere, as pieces of a puzzle might fit together; these are in turn verified by the observed results of the application of an idea to actual practice.

"The most ancient parts of truth . . . also once were plastic. They also were called true for human reasons. They also mediated between still earlier truths and what in those days were novel observations. Purely objective truth, truth in whose establishment the function of giving human satisfaction in marrying previous parts of experience with newer parts played no role whatsoever, is nowhere to be found. The reasons why we call things true is the reason why they are true, for 'to be true' means only to perform this marriage - function," he wrote.

James held a world view in line with pragmatism, declaring that the value of any truth was utterly dependent upon its use to the person who held it. Additional tenets of James's pragmatism include the view that the world is a mosaic of diverse experiences that can only be properly interpreted and understood through an application of "radical empiricism." Radical empiricism, not related to the everyday scientific empiricism, asserts that the world and experience can never be halted for an entirely objective analysis, if nothing else the mind of the observer and simple act of observation will affect the outcome of any empirical approach to truth as the mind and its experiences, and nature are inseparable. James's emphasis on diversity as the default human condition — over and against duality, especially Hegelian dialectical duality — has maintained a strong influence in American culture, especially among liberals. James's description of the mind - world connection, which he described in terms of a "stream of consciousness (psychology)", had a direct and significant impact on avant - garde and modernist literature and art.

In What Pragmatism Means, James writes that the central point of his own doctrine of truth is, in brief, that "Truths emerge from facts, but they dip forward into facts again and add to them; which facts again create or reveal new truth (the word is indifferent) and so on indefinitely. The 'facts' themselves meanwhile are not true. They simply are. Truth is the function of the beliefs that start and terminate among them."Richard Rorty claims that James did not mean to give a theory of truth with this statement and that we should not regard it as such. However, other pragmatism scholars such as Susan Haack and Howard Mounce do not share Rorty's instrumentalist interpretation of James.

In The Meaning of Truth, James seems to speak of truth in relativistic terms: "The critic's [the critic of pragmatism] trouble... seems to come from his taking the word 'true' irrelatively, whereas the pragmatist always means 'true for him who experiences the workings.' " However, James responded to critics accusing him of relativism, scepticism or agnosticism, and of believing only in relative truths. To the contrary, he supported an epistemological realism position.

In The Will to Believe, James simply asserted that his will was free. As his first act of freedom, he said, he chose to believe his will was free. He was encouraged to do this by reading Charles Renouvier, whose work convinced James to convert from monism to pluralism. In his diary entry of April 30, 1870, James wrote,

"I think that yesterday was a crisis in my life. I finished the first part of Renouvier's second Essais and see no reason why his definition of free will — 'the sustaining of a thought because I choose to when I might have other thoughts' — need be the definition of an illusion. At any rate, I will assume for the present — until next year — that it is no illusion. My first act of free will shall be to believe in free will."

In 1884 James set the terms for all future discussions of determinism and compatibilism in the free will debates with his lecture to Harvard Divinity School students published as "The Dilemma of Determinism." In this talk he defined the common terms "hard determinism' and "soft determinism" (now more commonly called "compatibilism").

"Old-fashioned determinism was what we may call hard determinism. It did not shrink from such words as fatality, bondage of the will, necessitation, and the like. Nowadays, we have a soft determinism which abhors harsh words, and, repudiating fatality, necessity, and even predetermination, says that its real name is freedom; for freedom is only necessity understood, and bondage to the highest is identical with true freedom."

James called compatibilism a "quagmire of evasion," just as the ideas of Thomas Hobbes and David Hume that free will was simply freedom from external coercion were called a "wretched subterfuge" by Immanuel Kant. James described chance as neither hard nor soft determinism, but "indeterminism". He said

"The stronghold of the determinist argument is the antipathy to the idea of chance... This notion of alternative possibility, this admission that any one of several things may come to pass is, after all, only a roundabout name for chance."

James asked the students to consider his choice for walking home from Lowell Lecture Hall after his talk.

"What is meant by saying that my choice of which way to walk home after the lecture is ambiguous and matter of chance?... It means that both Divinity Avenue and Oxford Street are called but only one, and that one either one, shall be chosen."

With this simple example, James was the first thinker to enunciate clearly a two stage decision process (others include Henri Poincaré, Arthur Holly Compton, Karl Popper), with chance in a present time of random alternatives, leading to a choice which grants consent to one possibility and transforms an equivocal ambiguous future into an unalterable and simple past. There is a temporal sequence of undetermined alternative possibilities followed by adequately determined choices. James’ two stage model effectively separates chance (the indeterministic free element) from choice (an arguably determinate decision that follows causally from one’s character, values, and especially feelings and desires at the moment of decision).

James did important work in philosophy of religion. In his Gifford Lectures at the University of Edinburgh he provided a wide ranging account of The Varieties of Religious Experience (1902) and interpreted them according to his pragmatic leanings. Some of the important claims he makes in this regard:

• Religious genius (experience) should be the primary topic in the study of religion, rather than religious institutions — since institutions are merely the social descendant of genius.
• The intense, even pathological varieties of experience (religious or otherwise) should be sought by psychologists, because they represent the closest thing to a microscope of the mind — that is, they show us in drastically enlarged form the normal processes of things.
• In order to usefully interpret the realm of common, shared experience and history, we must each make certain "over - beliefs" in things which, while they cannot be proven on the basis of experience, help us to live fuller and better lives.

The investigation of mystical experience was constant throughout the life of James, leading him to experiment with chloral hydrate (1870), amyl nitrite (1875), nitrous oxide (1882), and even peyote (1896). James claimed that it was only when he was under the influence of nitrous oxide that he was able to understand Hegel. He concluded that while the revelations of the mystic hold true, they hold true only for the mystic; for others, they are certainly ideas to be considered, but can hold no claim to truth without personal experience of such.

Like Sigmund Freud, James was influenced by Charles Darwin's theory of natural selection. At the core of James's theory of psychology, as defined in Principles of Psychology (1890), was a system of "instincts." James wrote that humans had many instincts, even more than other animals. These instincts, he said, could be overridden by experience and by each other, as many of the instincts were actually in conflict with each other. In the 1920s, however, psychology turned away from evolutionary theory and embraced radical behaviorism.

James is one of the two namesakes of the James - Lange theory of emotion, which he formulated independently of Carl Lange in the 1880s. The theory holds that emotion is the mind's perception of physiological conditions that result from some stimulus. In James's oft - cited example; it is not that we see a bear, fear it, and run. We see a bear and run, consequently we fear the bear. Our mind's perception of the higher adrenaline level, heartbeat, etc., is the emotion. This way of thinking about emotion has great consequences for the philosophy of aesthetics. 

James studied closely the schools of thought known as associationism and spiritualism. The view of an associationist is that each experience that one has leads to another, creating a chain of events. The association does not tie together two ideas, but rather physical objects. This association occurs on an atomic level. Small physical changes occur in the brain which eventually form complex ideas or associations. Thoughts are formed as these complex ideas work together and lead to new experiences. Isaac Newton and David Hartley both were precursors to this school of thought, proposing such ideas as “physical vibrations in the brain, spinal cord, and nerves are the basis of all sensations, all ideas, and all motions...” James disagreed with associationism in that he believed it to be too simple. He referred to associationism as “psychology without a soul” because there is nothing from within creating ideas; they just arise by associating objects with one another.

On the other hand, a spiritualist believes that mental events are attributed to the soul. Whereas in associationism, ideas and behaviors are separate, in spiritualism, they are connected. Spiritualism encompasses the term innatism, which suggests that ideas cause behavior. Ideas of past behavior influence the way a person will act in the future; these ideas are all tied together by the soul. Therefore, an inner soul causes one to have a thought, which leads them to perform a behavior, and memory of past behaviors determine how one will act in the future.

These two schools of thought are very different, and yet James had a strong opinion about the two. He was, by nature, a pragmatist, and therefore believed that one should use whatever parts of theories make the most sense and can be proven. Therefore, he recommended breaking apart spiritualism and associationism and using the parts of them that make the most sense. James believed that each person has a soul, which exists in a spiritual universe, and leads a person to perform the behaviors they do in the physical world. James was influenced by Emmanuel Swedenborg, who first introduced him to this idea. James states that, although it does appear that humans use associations to move from one event to the next, this cannot be done without this soul tying everything together. For, after an association has been made, it is the person who decides which part of it to focus on, and therefore determines in which direction following associations will lead. Associationism is too simple in that it does not account for decision making of future behaviors, and memory of what worked well and what did not. Spiritualism, however, does not demonstrate actual physical representations for how associations occur. James therefore chose to combine the views of spiritualism and associationism to create his own way of thinking that he believed to make the most sense.

James was the first president of the American branch of the Society for Psychical Research. The lending of his name made Leonora Piper a famous medium. In time James found the investigations of Piper's mysterious abilities boring.