SARTRE: A Biography By Ronald Hayman Simon and Schuster. 572 pp. $22.95 SARTRE: A Life By Annie Cohen-Solal Translated from the French By Anna Cancogni Pantheon Books. 591 pp. $24.95

JEAN-PAUL SARTRE -- who until 10 years before his death in 1980 was the dominant intellectual voice of postwar Europe -- is a fallen hero. Sartre emerged on the Parisian scene during and immediately after the German occupation, stepping from a welter of promising obscurity into a new kind of visibility, from which he rose to an embattled eminence greater than that enjoyed by any other intellectual in this century. Philosopher, novelist, playwright, polemicist, all these activities sustained him in his large role, which was to define the war of ideas for the Europe of his time, and fight among its greatest combatants.

How Sartre reached that pinnacle, and how he fell from it, is the substance of these two compelling books. In addition to his great gifts, Sartre was the stuff from which heroes are made. He had stature: the strength fully to live up to his own seriousness. He had courage: He lived in controversy, and no matter how vicious it became, it could not break him. Finally, he had an unfailing sense of his own fighting place in the crisis of European intellectual culture following World War II.

Yet he was more than all his roles. Twenty years ago, I counted myself among his countless hero-worshipers. I am struck now by a certain strain of romantic irrationality in my admiration. What, exactly, did I admire? To be truthful, while I found his formal philosophy very exciting as a verbal -- almost poetic -- game, as a description of actual consciousness it seemed first unconvincing and soon merely uninteresting. I never for a moment acceded to his lamentable politics. It was Sartre the writer who moved me, and greatly. His plays engage ideas with unequaled dramatic intensity: I defy anyone to shrug off the infernal machine of No Exit. Nausea and his short stories are among the most interesting fiction of his era. His literary and cultural essays -- the work in Situations -- are unforgettably incisive. His memoir of childhood, The Words, is among the really flawless pieces of French prose in this century. Despite the slack late work, Sartre was among the most virile and powerful stylists in modern letters. One of many, I took him for a model.

Yet finally I think his glamour derived most powerfully from the musk of some 20th-century romantic magic that Sartre exuded with unchallengeably hypnotic allure. To a degree almost without precedent in this century -- the exception is Ernest Hemingway -- Sartre was endowed with a talent, a separate autonomous gift, for fame. I do not mean empty celebrity. Sartre's fame was part of his heroism, and I invoke the word in its honorable antique sense: fame, the praise and recompense of heroes. He had an uncanny capacity to make himself the most visible part of his relation to any issue. (I'm interested to discover how he was influenced by Hemingway, especially by Hemingway's knack for making the smallest gesture seem to glow with deliberation and consciousness. "Me, I'm only a captain," Hemingway told him when they met. "You're a general.") From all this Sartre conjured up a rough, tough but very cerebral mystique of the isolated ego, a vision of the intellectual as solitary hero, a modernist romanticism of which Sartre made himself the Great Writer and sage. Nausea is The Sorrows of Young Werther for mid-century. To several generations of the young and bright, it was irresistible.

And it makes a fascinating life, or rather, lives -- for there is no Sartre without his lifelong companion, Simone de Beauvoir. The actual outline of their relationship, the subject of so much fantasy and myth about sexual openness, is of enormous interest. Add to their relationship the circles within circles of Parisian intellectuals who formed their apparatus, not to mention the vast network of his love life, and intrigue spreads, to become very grand.

OF RONALD HAYMAN'S biography and Annie Cohen-Solal's, I would say that on balance the superior book is clearly Hayman's. First of all, he writes much better than she does. Hayman works with a solid, lucid, balanced British prose which is far more adaptable to Sartre's complexity than is Cohen-Solal's. Though solidly researched and well put together, Cohen-Solal's enterprise is infected with a slack between-us chattiness that's recently been responsible for a great deal of very bad French style. Hayman is far more intellectually sophisticated than his French rival. He has a much more more lucid view of Sartre's philosophy and its implications; his literary judgments are as good or better; and because his grasp on psychoanalysis and depth psychology is firmer than hers, his picture of Sartre and de Beauvoir's motivations is more credible. (This last shows growth on Hayman's part: His earlier biographies of Brecht and Kafka struck me as very short on psychological insight.)

But both books are crammed with fascinating information. Who would have imagined, for example, that the title for Nausea was suggested at the last minute by Sartre's publisher, that pillar of the bourgeois establishment, Gaston Gallimard? Sartre's original title was a dull, Goethesque Melancholy. The change made the book, and identifies precisely the transformation of the romantic heroism over which Sartre presided. I had heard rumored, but never seen confirmed as it is here, that Sartre was a near-alcoholic and an amphetamine addict. I'd hazard that beginning with Saint Genet much of his style -- an energized, repetitious drive toward some perpetually unattainable lucidity -- derives from the effects of that drug. Certainly a number of the awful afflictions of his last years can be traced to it, and in Cohen-Solal's account especially, one senses that through his toxic addictions, Sartre paid a price for his need to stay forever visible, in battle, dominating the scene. We should not omit the painful story of Sartre's years of decline. Simone de Beauvoir wrote about them in a good book, Adieux, but certain rather sinister aspects are more fully handled here, especially the way the ailing Sartre used -- and was in turn both used and abused by -- his last assistant, an opportunistic young fanatic who emerged from the events of '68. It makes riveting reading.

In the larger balance of work, love and reputation, Sartre the artist is now at a low point, Sartre the political sage is close to discredited, and Sartre the man, as the companion of the leading French feminist of her era, in a kind of trouble these books can only deepen. I cannot remember the last time there was an important production in America of a Sartre play. As for the fiction, I'd guess only Nausea is still much read -- and a recent bump in its career is Denis Hollier's The Politics of Prose: An Essay in Sartre, a brilliant, hilarious, and all-but demolishing persiflage of the novel's structure and affectations. The autobiographical The Words remains a masterpiece, but even its standing will be troubled by these books, since both demonstrate that Sartre's account of his own past is grossly inaccurate.

Then there is the almost insurmountable problem of Sartre's politics. In political polemic, heroic stature is not quite enough. It also helps occasionally to be right. A short review makes a full analysis impossible, but it must be said that from the beginning, Sartre's political judgments were systematically and almost ludicrously unsound. He was wrong about Hitler, wrong about the Resistance, wrong about postwar Europe, wrong about the East-West struggle, wrong about totalitarianism, wrong about the future of France. An absolute reversal of the posthumous reputations of Sartre and his youthful companion, and later philosophical and political adversary, Raymond Aron, is only fashion's current testimony to an enduring problem. Exactly where Sartre was likely to be wrong, Aron was likely to be right. It does make a difference.

I FIND MYSELF gently reproaching both biographers for not summing up the relation to de Beauvoir more fully. Much is explained, but much also remains somewhat mysterious. Theirs was plainly a love match, and a peculiarly stable one at that, even though it floated inside an uncrossable moat of sado-masochism, and the famous "frankness" that defined it served a number of ends other than truth-in-intimacy. Sartre's girlfriends were numberless, part of his great-man apparatus, organized and compartmentalized in a thoroughly hierarchical fashion, with de Beauvoir steady in the center, admirer-in-chief. Except for her, he did not seek out women who were his peers, or even close. (Men either, for that matter). He seems to have been a charming, generous, gentle, ingratiating lover, far more interested in being admired and loved than he was in "conquest." It was de Beauvoir's job to witness and tolerate -- no, love and admire -- all this. The balance of this hard intimacy was maintained by elaborate formality; though they could finish each other's sentences, they addressed each other as "vous." Her dependency on him (partly denied in her feminism) was obvious and total: his on her was less obvious, and more personally (cruelly) denied. They were essential to each other and their partnership was authentic. Yet one senses that its leading characteristic was its entirely public, and publicized, nature. In fact, much of de Beauvoir's work consisted of writing and talking about it. The fact is that their intimacy was part of a public myth: each others' myth. And yet it was real.

Just as Sartre's stature is finally real. I am no longer much oved by his heroism. But it was authentic. I have come to greatly mistrust his "role" -- right and wrong -- in politics and culture. Yet he alone could have played it. Finally, he made himself into what the little prodigy and mama's boy dreamed of: one of the greatest French writers of his era. His funeral in April 1980 was one of the impressive events of recent intellectual history. Surrounded by a quite spontaneous crowd of, incredibly, 50,000 people, Sartre's hearse crawled through the Latin Quarter, across Saint Germain, past the cafe's he'd habituated, past the bookshops and kiosks and university hangouts that were his landscape, and then turned south toward Montparnasse. When the black van pulled into sight of the cemetery, the thousands broke into applause. The applause spread; it went on and on. It was the grand recessional of postwar intellectual life of Europe, and one could only lay down one's doubts and grieve. ::

Stephen Koch's books include the novels "Night Watch" and "The Bachelor's Bride" as well as "Stargazer," a study of Andy Warhol. He teaches at Columbia and is at work on a book about spies.