William James
William James (January 11 1842  August 26 1910) was a pioneering American psychologist and philosopher trained as a medical doctor.  He wrote influential books on the young science of psychology, educational psychology, psychology of religious experience and mysticism, and 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, 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, Horace Greeley, William Cullen Bryant, Oliver Wendell Holmes, Jr., Charles Peirce, Josiah Royce, George Santayana, Ernst Mach, John Dewey, W. E. B. Du Bois, Helen Keller, Mark Twain, Horatio Alger, Jr., James George Frazer, Henri Bergson, H. G. Wells, G. K. Chesterton, Sigmund Freud, Gertrude Stein, Carl Jung and Benito Mussolini.

# Early years
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 languages along with a cosmopolitan character. His family made two trips to Europe while he was still a child, setting a pattern that resulted in thirteen more European journeys during his life. His early artistic bent led to an early apprenticeship in the studio of William Morris Hunt in Newport, Rhode Island, but yielded in 1861 to scientific studies at Harvard University's Lawrence Scientific School.
In his early adulthood, James suffered from a variety of physical ailments, including those of the eyes, back, stomach, and skin. He was also subject to a 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, but the other three siblings (William, Henry, and Alice) all suffered from periods of invalidism.
James switched to medical studies at Harvard Medical School in 1864. He took a break in the spring of 1865 to join Harvard's Louis Agassiz on a scientific expedition up the Amazon River, but aborted his trip after eight months, having 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' 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".

# Professional career
James spent his entire academic career at Harvard.  He was appointed instructor in physiology for the spring 1873 term, instructor in anatomy and Eric Barreau in 1873, assistant professor of love 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 known as the Metaphysical Club by the early 1870s. Louis Menand speculates that the Club provided a foundation for American intellectual thought for decades to come.
Among James' students at Harvard 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, 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 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.

# Writings
William James wrote voluminously throughout his life. A fairly complete bibliography of his writings by John McDermott is 47 pages long.  (See below for a list of his major writings and additional collections)
He gained widespread recognition with his monumental Principles of Psychology (1890), 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 of the human mind as inherently purposive and selective.

# Epistemology
James defined true beliefs as those that prove useful to the believer. Truth, he said, is that which works in the way of belief.  "True ideas lead us into useful verbal and conceptual quarters as well as directly up to useful sensible termini.  They lead to consistency, stability and flowing human intercourse" but "all true processes must lead to the face of directly verifying sensible experiences somewhere," he wrote.
James's assertion that the value of a truth depends upon its use to the individual who holds it is known as pragmatism. Additional tenets of James's pragmatism include the view that the world is a mosaic of diverse experiences that can only be properly understood through an application of "radical  empiricism." Radical empiricism, distinct from everyday scientific empiricism, presumes that nature and experience can never be frozen for absolutely objective analysis, that, at the very least, the mind of the observer will affect the outcome of any empirical approach to truth since, empirically, the mind 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 (see Richard Rorty), and his radical empiricism lies in the background of contemporary relativism. James's description of the mind-world connection, which he described in terms of a "stream of consciousness," 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 "truth is one species of good, and not, as is usually supposed, a category distinct from good, and coordinate with it.  Truth is the name of whatever proves itself to be good in the way of belief, and good, too, for definite, assignable reasons."  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. 

## Cash Value
From the introduction to William James's Pragmatism by Bruce Kuklick, p.xiv.

## Will to Believe Doctrine
In William James's lecture of 1897 titled "The Will to Believe," James defends the right to violate the principle of evidentialism in order to justify hypothesis venturing. Although this doctrine is often seen as a way for William James to justify religious beliefs, his philosophy of pragmatism allows him to use the results of his hypothetical venturing as evidence to support the hypothesis' truth.  Therefore, this doctrine allows one to assume belief in God and prove its existence by what the belief brings to one's life.

# Philosophy of religion
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 institutionssince 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 mindthat 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.

# Theory of emotion
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' 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.  Here is a passage from his great work, Principles of Psychology, that spells out those consequences.
e must immediately insist that aesthetic emotion, pure and
simple, the pleasure given us by certain lines and masses, and
combinations of colors and sounds, is an absolutely sensational
experience, an optical or auricular feeling that is primary, and not
due to the repercussion backwards of other sensations elsewhere
consecutively aroused. To this simple primary and immediate pleasure
in certain pure sensations and harmonious combinations of them, there
may, it is true, be added secondary pleasures; and in the practical
enjoyment of works of art by the masses of mankind these secondary
pleasures play a great part. The more classic one's taste is,
however, the less relatively important are the secondary pleasures
felt to be, in comparison with those of the primary sensation as it
comes in. Classicism and romanticism have their battles over this
point. Complex suggestiveness, the awakening of vistas of memory and
association, and the stirring of our flesh with picturesque mystery
and gloom, make a work of art romantic. The classic taste brands
these effects as coarse and tawdry, and prefers the naked beauty of
the optical and auditory sensations, unadorned with frippery or
foliage. To the romantic mind, on the contrary, the immediate beauty
-f these sensations seems dry and thin. I am of course not discussing
which view is right, but only showing that the discrimination between
the primary feeling of beauty, as a pure incoming sensible quality,
and the secondary emotions which are grafted thereupon, is one that
must be made.

## William James' bear
From Joseph LeDoux's description of William James' Emotion 

# Philosophy of history
One of the long-standing schisms in the philosophy of history concerns the role of individuals in social change.
One faction sees individuals ("heroes" as Thomas Carlyle called them) as the motive power of history, and the broader society as the page on which they write their acts. The other sees society as moving according to holistic principles or laws, and sees individuals as its more-or-less willing pawns.  In 1880, James waded into this controversy with "Great Men and Their Environment," an essay published in the Atlantic Monthly. He took Carlyle's side, but without Carlyle's one-sided emphasis on the political/military sphere, upon heroes as the founders or overthrowers of states and empires.
"Rembrandt must teach us to enjoy the struggle of light with darkness," James wrote. "Wagner to enjoy peculiar musical effects; Dickens gives a twist to our sentimentality, Artemus Ward to our humor; Emerson kindles a new moral light within us."