IF A Stroll with William James suggests a leisurely

reminiscence, then the title of this book is misleading; but when we recognize the voice as that of Jacques Barzun, we should not be surprised to find a brilliant, witty, and entertaining reappraisal of the man whom Barzun considers to be one of the giants in psychology and philosophy, and as great a literary artist as his brother Henry, the novelist. No one has a better right to make such a claim than Mr. Barzun, who has already traced the evolution of the modern mind from 1750 to 1890 in distinguished interpretations of Darwin, Marx, Berlioz, and Romanticism. Now in this book he extends his intellectual history to William James' death in 1910.

In 1890, after 12 years of labor and personal difficulties, James published his monumental Principles of Psychology, the first scientific and exhaustive study of the subject. Barzun calls it "an American masterpiece," and like Melville's Moby Dick, "it ought to be read from beginning to end at least once by every person professing to be educated." Like Moby Dick, too, it is the narration of a search, a search for the human mind:

"How, from multiple sensation--the 'one great blooming, buzzing confusion' of the infant's encounter with the world--comes such an extraordinary entity as the warm particular self each of us knows, with its perceptions, will, judgment, habits, emotions, preferences; and its undetermined powers: its capacity to abstract and remember, to suffer and utter in myriad languages, to create art and philosophize, to invent systems of writing and of algebra; and with the aid of puny limbs and muscles to bore through mountains, bridge abysses, and reach the moon."

Everything James wrote was based in experience, and no previous investigator of the human mind had such varied experiences. Educated by a rapid succession of private tutors and experimental schools in Europe and the United States, which always disappointed his eccentric father, he felt deprived of formal training, but gained fluency in French, German--and English.

James had difficulty in finding his vocation. He studied painting for a few months under William Hunt, but science interested him more. Unqualified to enroll in Harvard College, he was accepted in the new Scientific School, where he studied chemistry, biology and anatomy. He was admitted to the Harvard Medical School, dropped out to accompany Louis Agassiz on a scientific expedition to Brazil, and dropped out again to seek in Germany a cure for his psychosomatic back pains. Though his health improved little, he read German books on "psycho-physics" and talked with leading scholars in the field. On returning to Harvard, he completed the requirements for the M.D. degree, but had no desire to practice medicine.

An appointment as instructor in physiology at Harvard enabled James to control (though not cure) his neuroses. He found it an easy step from teaching physiology to psychology, for which his medical studies, his wide scientific reading in three languages, and self- examination had qualified him better than anyone else in the country. He established a psychological laboratory, the first in the country, in which he trained a generation of American psychologists. It was by introspection, however, that he gained his greatest insights, or at least was able to supplement scientific experiments in a way no one else had thought of.

Philosophers as far back as Plato had tried to separate rationality and emotion, "feeling" and "thinking." James found, as Barzun says, "that mind and emotion, head and heart, are not contending parties, one of which may lose by the decision of some inner umpire." Rather, "thoughts" and "emotions," are integral and inseparable parts of experience, and completely objective thinking ("cool reason") is an impossibility. Together they are a process, which begins withy.. sensation and ends in action. This process is not automatic; all his life James rejected Determinism. The brain receives many messages through the sensory organs, from which it selects those it "will attend to"; and if it decides not to act, that is also an end-product of the process.

What "consciousness" is, James admitted he did not know, or "mind" either. But by introspection he could examine the contents of consciousness. Impressions, "thoughts," he found, flow in a "stream of consciousness." This was a basic observation in his Principles of Psychology' (though he first called it "stream of thought"), and a stepping-stone to his philosophy of Pragmatism, Pluralism, and Radical Empiricism.

As Barzun says, in the 20th century "wishful thinking is used as a pejorative clich,e to question the truthfulness of an idea or thought. James was as strongly opposed to self-delusion as anyone, but he showed that all thinking is "wishful"; in Barzun's neat summary, "the mind works to serve wants, ideas are the product of desire."

James' discovery of the way the mind works led to his philosophy of Pragmatism, though it is not a philosophy, and the term has taken a pejorative meaning completely at variance with his intentions. When someone calls a politician "a pragmatist," it usually means, "he will do whatever is necessary to win," without regard to ethics.

Plato taught that "Truth" is eternal, existing outside the world of sense. But it is a notorious fact in human experience that what is accepted as truth in one time and place is often rejected or altered in another. Yet the idea that truth is relative is repugnant to most people. How, James asked, can we say with confidence, "This is true, that is not"? Himself trained in science, he used the method of induction by which scientists have explored the secrets of nature: collect the facts, compare them objectively, form a tentative hypothesis, then test it in application. This is the Pragmatic method.

"Truth," says James, is simply a collective name for verification processes, just as health, wealth, strength, etc., are names for other processes connected with life. Truth is made, just as health, wealth, and strength are made, in the course of experience. The "truth" is the result, and it need to be constantly reverified.

James' theory of truth was the natural result of what he discovered the stream of consciousness to be: a meaningless flux, until the human mind and will make order out of it. The analogy that fits James' empiricism, Barzun says, "is the artistic . . . it is we who project order into the world by selecting objects and tracing relations so as to gratify our intellectual interests." James conceived the world as "a forest or a block of marble from which parks or statues may be produced by eliminating irrelevant trees or chips of stone."

Most philosophers write a dense prose which only other philosophers understand, but James' artistic view of the world of experience made him a great prose stylist, able to write not for the specialist, but for a literate public. His prose is limber, vivid, and virile, because it conveys the imagery of real life. As different as William and Henry were in temperament and lifestyle, Barzun believes they shared a similar view of the mind and experience. What Henry wanted to convey in fiction, he noted in 1893, was "the multitudinous presence . . . the surge of life." His novels became increasingly concerned with his characters's consciousness--and conscience. Barzun is scornful of the biographers who see William and Henry divided by sibling rivalry. They learned from each other, their Swedenborgian father, and the "new consciousness" of the 1890s.

Though Freud is often spoken of today as the discoverer of the unconscious, James was writing as early as 1872 (when Freud was only 16) that, in Barzun's words, "the subliminal self forms with the conscious mind a continuous spectrum, not distinct layers with a corridor between," as Freud believed. "James respected the rich contents of the subliminal self. The flights of genius are 'uprisings from below' and so are the highest religious visions." When he wrote The Varieties of Religious Experience, he refused to call any of the experiences delusions because they had pathological origins. All were genuine experiences, deserving unbiased observation and tolerant description. As "a positivist Freud felt he must deny to religion and philosophy any valid insights into the mind." He could see in the pragmatists, whom he called "anarchists," nothing but defenders of "wishful-thinking." However, "Freud's system contains not a scrap of empirical observation but is all inference, fashioned into constructs and analogies so as to fit situations inherently confused."

This James condemned as "reductionism," which Barzun calls "the prevailing form of polemics in the twentieth century. We owe it to the popularity of Freud and Marx, whose systems imply that any resistance to them proves how right they are." Barzun has no patience with the psychoanalytic biographers who try to find a "ruling passion" in every character, a notion as silly as Ben Jonson's superstitious "humors". They fail to deal with the "complexity of the vast, many-layered unconscious first studied so fruitfully in the Jamesian era."