William James (1842–1910), brother of novelist Henry James, was a psychologist, physician, and philosopher. For William James, pragmatism was personal and pluralistic. His attention to the affective elements of experience, such as feelings of volition, intention, and personal identity, mark the breaking point from Peirce's version of pragmatism. James was always more the psychologist, Peirce the logician and mathematician. Author of numerous influential books and essays, James's popularizing of pragmatism gained both him and the movement great notoriety.
James's landmark The Principles of Psychology (1890) described consciousness as an activity of selection. This selection occurs within a "stream of consciousness" (a term coined in The Principles). James worked to make psychology a natural science, using human physiology and employing the scientific method.
In "The Will to Believe" (1897), James advocated a freedom of choice or belief when empirical evidence does not provide sufficient warrant to commit us to one belief or another, and when the situation presents us with a "forced, living, and momentous" decision. Here James employed the notion of selectivity he had earlier developed to describing the volitional function of consciousness.
In Pragmatism (1908) and Essays in Radical Empiricism (1912), James went on to develop a nondeterministic and nondualistic theory of knowledge. In these works, James advocated the notion of truth as the "cash value" of a proposition or belief. James called for a consideration of philosophical dilemmas in terms of the effects of their resolutions. If it benefits us to hold a particular belief, we should take those benefits into account when considering the advisability of adopting such a belief as true.
In addition to Peirce, James's influences include Charles Bernard Renouvier (1815–1903) and F. C. S. Schiller (1864–1937). For example, James's diary entry from April 30, 1870, addressed Renouvier's definition of free will as "the sustaining of a thought because I choose to when I might have other thoughts." James's response was to write, "My first act of free will shall be to believe in free will…I will assume for the present—until next year—that it is no illusion." And James worked with Schiller to establish pragmatism as a form of humanism.
Perhaps the most important philosopher to benefit directly from James's work was American educator, psychologist, and public philosopher John Dewey.