EVEN YOUR LIBERAL FRIEND who banished John Dos Passos forever as a political turncoat should enjoy Professor Townsend Ludington's fine, sweeping study. He shows in full color Dos Passos the paradox, the self-contradiction, the eccentric of such proportions that the mere facts of his life would make arresting reading even had he had no particular genius. Was there ever a man so concerned about our democracy who yet kept departing our shores as if fleeing the plague? Was there ever a revolutionary who become ultimately so reactionary? A writer so concerned about theme and technique who yet, for a time, thought of making his career in painting? A man so shy who had so many friends? One so broke who spent money so freely? So discerning/superficial, so forthright/ambiguous, so heretical/orthodox, etc., etc.?

Born out of wedlock in 1896, Dos Passos spent much of his childhood hidden away in Belgium and england with his mother, Lucy Madison, so that he would not embarrass his father, a wealthy Washington corporation lawyer, and his father's estranged Catholic wife. When that lady died in 1912, John's father married John's mother and Jack Madison, then a senior at Choate, allowed that he had better wait until he entered Harvard before he became openly John Dos Passos. There would be less explaining to do. Sensitive about his illegitimacy and his 16-year concealment, he had to struggle against his feeling of being an outsider. Yet the world was his oyster, and all his life he was to pop off to Marrakesh or Brasilia or Tehran or Tiflis with as little forethought as most would give to an intrastate journey. If he inherited some of the brilliance doctrinaire conviction of his kindly though arrogant father, he also drew a drop or two of his mother's whimsy and impracticality.

Young John had poor eyesight but read copiously. He stuttered but spoke fluent French. He was hopeless at atheletics but a hiker ready to reel off 20 miles with or without a companion. An honor graduate at Choate, he was sent by his father on the obligatory grand tour of Europe and the Middle East, complete with tutor at his side. At Harvard his sophistication in travel an art existed queerly alongside his diffidence -- even a streak of naivete -- where one would expect sangfroid and savvy. He devoured the classics, composed vigorous poetry, kept a diary, was active in literary affairs and wrote innumerable letters. He dodged women, failed to make the smart clubs but graduaged cum laude and formed an enduring friendships with classmates including E. E. Cummings, Robert Hillyer, Stewart Mitchell and Dudley Poore.

Intuitive rather than deductive, he was seldom a model of logic. There was a bashful friendliness and charm about him at odds with the indignant opposition to authority and bureaucracy which came to be one of his strongest traits. His indulgent father sent him to Spain to study architecture as he absorbed the language and literature. Returning to New York 1917, he mixed with Greenwich Village radicals and cherished magazines like the left-wing The Masses and the pacifist Seven Arts before he joined an ambulance unit in France. He saw the war there, and later in Italy, with the eye of a novelist-moralist determined to strip this killing of glamour and place the blame where it belonged. Fat, pompous men of authority had committed the crime of bringing on war. It was the poor, and the young, who paid for it. His reactions were less like those of his contemporaries than of young men decades later in the Vietnam It was "swag-bellied old fogies in frockcoats" who had made a "'God-damned mess' of things," and he wrote furiously in his journal, "down with the middle aged!"

His Three Soldiers , with its debunking portrayal of war's effects on ordinary doughboys, drew praise on the left and denunciation on the right (a "textbook and bible for slackers and cowards," said one). Dos Passos not only propagandized and picketed for Sacco and Vanzetti. He interviewed them both in their cells, was briefly jailed himself for excessive indignation, and wrote it up for The New Masses . For a time he had the wary approval of that basilisk of the New York Communists, Mike Gold. He was beloved by radicals, a bosom friend of his onetime ambulance-driving sidekick, John Howard Lawson.

Off to Europe at every whim, he was as at home with the Hemingways, Fitzgeralds and Gerald Murphys as he was on Cape Cod with Edmund Wilson -- the latter a particulary engaging friend and critic. What with his travels, friendships, letters, causes and occasional bouts with rheumatic fever, the wonder is that in his time Dos Passos could turn out some 30 books and much shorter material. Might not the general quality have been higher had he spent less time on ships, planes and Riviera terraces and more with the lamp?

With Manhattan Transfer (1925) Dos Passos envolved the stylistic innovations that he enlarged and used with smashing effect in his magnum opus, the U.S.A. trillogy of the '30s composed of The 42nd Parallel, 1919 and The Big Money . This fictional representation of the first three decades of this century, with its bold and cocky interspersion of contemporary atmosphere and stream-of-consciousness observation in such devices as the "Newsreel" and "Camera Eye," rocket him to fame, put him on the cover of Time and actually made him some money. (He made less than $1,000 in 1935.)

But while it depicted an America in capitalist decay, its violations of the Communist line were legion and he was denounced by the brotherhood. No loger was Lawson his friend. Indeed Dos Passos was never a Marxist. Worse yet, as this biography suggests, he never truly developed his political radicalism into fullblown method and system. He was poet, artist, impressionist -- seldom dialectician or logician.

But as businessman he was worst of all. His father had left him huge acreage property in Virginia which Dos Passos entrusted to the care of others. For decades they collected a small fortune while he, never suspecting, was given a driblet. O, splendid innocence of the Camera Eye! His finances were chaotic. He often borrowed from friends, touching one to repay another, flying a kite repeatedly to Hemingway, with whom he fished and corresponded. He lived habitually beyound his means. He took off on journeys first class while in straits at home.

In 1937, when Dos Passos was in beleaguered Madrid with Hemingway and others supporting the Spanish Republic, his suspicions of the Communists turned to rage when he learned that they had murdered his friend Jose Robles because of political divagations. His accommodation with the Communists -- never ardent, never by the book -- ended. He quarreled with Hemingway, who was thereafter characteristically savage toward him. His righward shift accelerated, eventually reaching his espial of Reds under the bed, his cold-war approval of McCarthyism and his support of Goldwater and the Vietnam war. He became one of those middle-aged men he had once cursed. Always honest, he was politically simplistic and emotional. He studied Jefferson for years, but his book on that statesmen lacked understanding.

He avoided public speaking out of stage-fright. He usually fled the country when a book of his was published, as if distance lent safety. His marriage to Katherine Smith in 1929 brought him domesticity on Cape Cod or wherever he happened to be at the moment, but oh, those money problems! She died at his side when -- that poor vision again -- he smashed his car into a truck. He lost an eye but recovered to marry Elizabeth Holdridge two years later and to become a father for the first time.

Ludington, of the University of North Carolina, who previously edited Dos Passos' letters and diaries, moves so grandly with his preambulatory subject that we can forgive him if he is a mite lenient on the critical side. He has a higher opinion of Dos Passos' later writings than most. As biographer, his view is steady, informed, tolerant and researched in depth. We are carried again through one of our most turbulent political and literary eras, this time in the person of a man brilliant, vulnerable, erratic, seized by ideas tempestuous and often surprising. "The extreme shift in his political affiliations . . . was difficult to comprehend," Ludington agrees. But for all Dos Passos' senescent vagaries, he remains warm and understandable in this richly detailed appraisal. Not for many of us are our sins redeemed by such an original, exciting, triplebound tour de force as U.S.A .