The Smart Squad : LUDWIG WITTGENSTEIN; The Duty of Genius <i> By Ray Monk (The Free Press, a division of Macmillan: $29.95; 654 pp.) </i>

The philosopher Ludwig Wittgenstein may be the most famous obscure intellectual of the century. It’s hard to imagine a more unwilling celebrity than this profoundly serious man who shunned publicity and devoted his life to the pursuit of clarity. Since his death in 1951, however, he has emerged as one of the best known and least comprehended contemporary thinkers.

He’s the “Mad Genius” as sent by Central (European) Casting, the savior of British philosophy or its trivializer. He is passionate, tormented, misunderstood, a man so singular that virtually everyone who ever knew him, from Bertrand Russell to the man who delivered peat to his cottage in Ireland, remembered and wrote about him. He reminded one student of “the Norse God Baldur, blue-eyed and fair-haired, with a beauty that had nothing sensual about it.” Others were less enthusiastic. One young boy told his diary: “Witkinstein (sic) is an impossible person everytime you say anything he says ‘No No that’s not the point.’ ”

He was equally hard on himself, a master of self-laceration who often contemplated suicide. Though baptized a Catholic, he was of Jewish descent, a heritage he sometimes blamed for his moral and mental inadequacies in language reminiscent of “Mein Kampf.” (Curiously, Hitler and Wittgenstein attended the same school for a year; there’s no evidence that they met.)

Though he wrote constantly, he revised constantly too; most of his work has been posthumously published, and generates hundreds of scholarly books and articles each year. A recent bibliography lists nearly 6,000 items.

Outside the academy, Wittgenstein is a cultural presence to many who know him only as a name, or the inspiration for a sizable body of music, art and writing. His words have been rendered in dance and neon; there’s even a poem about his lecturing style. He’s a character in several novels and is mentioned in plays, on public television and by Woody Allen.

For those who want to learn more about his fascinating figure, Ray Monk’s thoughtful and accessible biography, intended for the general reader, encompasses the life and work in a single narrative, illuminating the values implicit in both.

The book’s subtitle, “The Duty of Genius,” is taken from Otto Weininger’s “Sex and Character,” which Monk believes is the source of many of Wittgenstein’s attitudes toward life and love. Weininger, a misogynist and anti-Semite, believed it was man’s duty to conquer the flesh and to discover and realize his genius--or to kill himself. A Jew and a homosexual, Weininger shot himself at 23, in the house where Beethoven, his hero, died. Suicide greatly increased both Weininger’s moral prestige and the sales of his book, which Wittgenstein read as an adolescent.

Though Monk’s is not the authorized biography, he enjoyed the complete cooperation of Wittgenstein’s literary executors, who permitted him to quote from previously unpublished material, including diary entries written by Wittgenstein in code about his homosexuality, which has been the subject of an unseemly, irresistible debate. Much of Monk’s research will be new to even avid readers of Wittgensteiniana; those unacquainted with Wittgenstein’s philosophy will find Monk’s explanations helpful and unforbidding, if not exactly a piece of Sacher torte.

Wittgenstein was born in Vienna in 1889, the eighth child of an extremely rich, cultivated and ill-fated family. His father was a steel magnate on the order of Andrew Carnegie, his mother a musically gifted patron of the arts. Three of the brothers committed suicide; the fourth, Paul, continued his career as a concert pianist despite the loss of an arm in World War I.

The world is fin de siecle Vienna, the city Karl Kraus called “the research laboratory for world destruction”; the birthplace of Nazism and Zionism; the Vienna of Sigmund Freud, Arnold Shoenberg and Adolph Loos. Like these contemporaries, Wittgenstein broke away from the historical outlook in his field: His linguistic analysis is a radical departure in philosophy, analogous to psychoanalysis in psychiatry, atonality in music and functionalism in design.

Wittgenstein’s originality seemed especially pronounced in the alien culture of England, where he spent much of his working life. He went to Manchester as a young man to study engineering, then took up aeronautics and, finally, mathematical logic at Cambridge with Bertrand Russell, who introduced him to G. E. Moore, John Maynard Keynes and other Apostles of Bloomsbury.

At the outbreak of World War I, Wittgenstein enlisted in the Austrian artillery, hoping to die or to change his life. He fought on the Russian front, was decorated for bravery and taken prisoner in Italy. When he was captured, he had with him the manuscript of the “Tractatus Logico-Philosophicus,” the only one of his books published in his lifetime, a work as magisterial as its title suggests, and best understood (if at all) in the context of Wittgenstein’s war experience. Here Monk’s approach is particularly apt, revealing, as Wittgenstein insisted, that “the point of the book is ethical.”

So was the point of Wittgenstein’s life, which shows the strong ethical views that the “Tractatus” says cannot be spoken of, only made manifest. He sought a life of Christian virtue as conceived by Tolstoy, and seems to have taken the ideals of poverty, chastity and duty more seriously than his mentor. He relinquished his fortune to his sisters and brother and lived very simply, in barely furnished rooms, once telling a friend: “I don’t care what I eat as long as it’s the same thing every day.” Since sex and love were incompatible, he was tortured by sexual guilt over even fantasized transgressions.

He grew to see philosophy as his duty, and devoted his life to it after he returned to England in 1929 and began the work which culminated in the “Philosophical Investigations,” the most polished and influential of the later books.

Here Wittgenstein rejects the classical view of philosophy as the attempt to answer ultimate questions. Philosophical problems, he writes, are not about matters of ultimate (or any kind of) fact; they arise from linguistic misunderstandings, from mistakes in logical grammar. The job of the philosopher, as he sees it, is to “ command a clear view of the use of our words.” Philosophy is not a theory, but an activity, “a battle against the bewitchment of our intelligence by language.”

Consider a question like “What is time?” Because it is similar in form to “What is dew?,” it misleads us into looking for something we can point to or describe, as we would the dew. Thus the endless philosophical theories about the nature of time. The Wittgensteinian philosopher resists the “craving of generality.” Instead of theorizing about time, he minutely examines how the word is used (how we teach it to children, for example), and is no longer puzzled. He can teach it, he can measure it, he can be on it. The meaning of time is not some mysterious metaphysical something, it is, roughly, its use in the language.

Philosophy is a therapeutic enterprise, Wittgenstein believed, a set of related techniques for dispelling linguistic confusions. This approach seemed exhilarating and effective to many philosophers; others, including Bertrand Russell, condemned it as a cop-out, a refusal to think seriously.

The controversy persists. In “The Legacy of Wittgenstein,” Anthony Kenny suggests that “Wittgensteinian philosophy as opposed to Wittgensteinian scholarship has not made progress, and some of the philosophical gains we owe to (him) seem in danger of being lost.”

During his lifetime, Wittgenstein was a cult figure in philosophy. In his lectures, he struggled visibly with his thoughts, which often were expressed in imaginative questions and aphorisms. His gestures and intonations were distinctive and much imitated; he feared, perhaps rightly, that his influence was destructive to his students. To him, the profession of philosophy was “a living death,” but all he was fit for; he urged his students to take up something useful, like medicine or manual labor, especially if they were serious philosophers. (He himself worked as a gardener in a monastery, and as a hospital orderly in London during World War II.) Philosophy was worthless unless it helped you to live a morally better life.

Wittgenstein did not permit “tourists” at his lectures, and the chances are, that’s you. Monk is considerably more hospitable, yet travelers should expect a fairly rigorous journey. Nevertheless, the book is engrossing, especially if read in conjunction with Wittgenstein himself. In Monk’s comprehensive account, certain features of Wittgenstein’s thought seem remarkably current. He is deeply suspicious of science and scientism, more interested in differences than in similarities, against abstraction and for contextual interpretation. And always, spirit prevails.

So what if he’s tough. There are worse ways to spend the fin de siecle.