IF I HAD A HAMMER . . . The Death of the Old Left and The Birth of the New Left By Maurice Isserman Basic Books. 259 pp. $18.95

ONE OF the folk songs that most stirred young campus rebels in the 1960s was Peter, Paul and Mary's version of "If I Had a Hammer." The lyrics proclaimed: "It's the hammer of justice,/ It's the bell of freedom,/ And a song about love between/ My brothers and my sisters/ All over this land." For Maurice Isserman, who teaches history at Smith College, the song evokes the euphoric mood of the New Left, and he has written this book at least in part to protect the memory of his own exhilarating youthful initiation into radical politics. In 1968, when the Students for a Democratic Society (SDS) had reached its apex of popularity, Isserman was a 17-year-old college freshman and "a proud new member" of SDS. A year later, the largest radical movement since the 1930s, with close to 100,000 members, was taken over by the bomb-throwing Weathermen and shortly after self-destructed.

Since 1970 a number of memoirs have tried to recapture the aura of innocent idealism and comradeship with which, at least in benign retrospect, the movement was launched between 1960 and 1962. Earlier this year there was published, to much acclaim, James Miller's Democracy Is in the Streets": From Port Huron to the Siege of Chicago, a richly footnoted scholarly effort to rehabilitate the SDS, to separate its buoyant inception from its disastrous end. Although Miller was a member of one of the saner factions of SDS and now recognizes serious flaws in the ideas and actions of the founders, he still insists that "they helped launch America's last great experiment in democratic idealism."

Maurice Isserman is more reserved in his admiration and more enterprising in his thesis, which finds greater continuity than the generally assumed discontinuity between the Old Left and the New Left. To sort out what went wrong from what went right, he turns his attention to the pathetically small Old Left movements of the 1950s which, in his view, provided most of the ideas, moods and organizational structures that were later absorbed and transformed by SDS. The uninitiated can easily get lost in the intricate maze through which Isserman conducts the reader: Communist Party factions formed after Khrushchev's denunciation of Stalin in 1956, Trotskyist and ex-Trotskyist socialist sects, a half dozen pacifist societies, at least as many leftist youth groups operating on college campuses, to say nothing of those theoretical reconsiderations about the entire radical tradition reflected in the pages of Dissent, which the author calls a "journal of tired heroism." Luckily, despite his sad tales of bewildering sectarian machinations, Isserman focuses on a few outstanding figures -- Max Schachtman, Irving Howe, A.J. Muste, and Michael Harrington -- who placed their strong imprint on various peripheral yet influential grouplets.

No colorful personalities emerge in the opening chapter on the collapse of the Communist Party, which went from 20,000 members in 1956 to 5,000 in 1958. Years of strict discipline and proscription against unorthodox thoughts had flattened out individuality among the leaders. Many of the party members who dropped out retained, despite their anger at having been deceived about the Soviet Union, certain instinctive political responses that could be dubbed "Stalinoid" -- a lingering defensiveness about the Soviet Union, a readiness to believe the worst about the United States, and a susceptibility to amorphous populist slogans, especially when embodied in folk songs. In varying degree, these attitudes were transmitted to their children (Isserman calls them "red diaper babies") who in the 1960s constituted the largest single entity on campus amenable to SDS recruitment.

The Communist debacle created new opportunities for leftist groups not tainted with Stalin's crimes. One of them was the tiny Independent Socialist League (later merged with the Socialist Party) led by Max Schachtman, a former follower of Leon Trotsky and a devastating polemicist who had a gift for spotting and nurturing talented young intellectuals -- among them Irving Howe and Michael Harrington. Schachtman's influence on the budding New Left was mainly indirect, through his disciples in the Young People's Socialist League (by default, the largest radical youth group during the late 1950s) and in the League for Industrial Democracy, which became the parent organization and main source of funds for SDS.

Among Old Leftists, Michael Harrington, who was to achieve fame as the author of The Other America and as a catalyst for the War Against Poverty, established the closest rapport with SDS leaders, especially with Tom Hayden who shared his midwestern Catholic background. Harrington's principal achievement was to secure the insertion of a brief anti-communist paragraph in the SDS Port Huron (Michigan) Statement of 1962, to balance the much longer denunciation of anti-communist and anti-Soviet "paranoia." (In 1965, that paragraph was quietly dropped.) Recently, Harrington has expressed regret that he pushed so hard on this issue and thereby intensified the SDS leadership's resentment against their "patronizing" elders. It could be argued, on the other hand, that generational resentment is no excuse for historical ignorance or for backsliding on the SDS's clear commitment to democratic principle.

THE INFLUENCE of Dissent, a magazine of socialist reexamination founded by Irving Howe and friends in 1954, on the student New Left is hard to estimate. Certainly the editors' call for "rethinking, reformulation, controversy and openness of ideas" matched the mood of the young radicals. In 1962 Dissent's editors met with Tom Hayden and other SDS leaders to exchange ideas, only to find themselves deadlocked on the same issue of anti-communism. Isserman's attitude toward Dissent is ambiguous. On the one hand, he finds it a repository of hard-won wisdom gained from past battles. On the other hand, he chides the editors for missing the revolutionary boat because they took the lessons of the past too seriously.

The final source of influence on the New Left, according to Isserman, was the pacifist movement, led principally by the late A. J. Muste, a saintly man of ministerial background with much experience in labor and radical circles. Though small in number, the pacifists appealed to the anti-ideological and activist predilections of the New Left by their stress on moral values and their personal courage in performing acts of conscience (e.g., placing their lives at risk in opposing nuclear tests). Yet in the period after 1965, when the New left concentrated on opposition to the Vietnam War and when the principled nonviolence of the pacifists might have restrained the "crazies," the Student Peace Union, depleted by internal dissension, had vanished from college campuses.

As someone who in the distant past encountered and admired the three main figures in Isserman's book, I could not help finding parts of his narrative absorbing. By persistence in interviewing many of the surviving actors in his sectarian drama, he has meticulously resurrected an obscure bypath of political history. Yet even for me much of the detail seems excessive and irrelevant to the declared theme of the book, the continuity between the Old and the New Left.

Even more troubling is Isserman's reluctance to work out a just balance-sheet of SDS accomplishments and failures. He does not mention the harmful effect on university atmosphere and curriculum of the New Left's bullying style of activism. He agrees with the SDS leaders that the issue of communism, raised by sophisticated elders, was stale and not pertinent to the 1960s. In fact, SDS alienated the larger public and weakened the antiwar movement precisely because of its blind support of North Vietnam, along with its virulent anti-Americanism.

Isserman concludes, rather ambivalently, that the failure of the New Left was due both to youthful resistance to the moral and tactical lessons learned by their elders and to excessive ardor on the part of those same elders in trying to impose their cautious wisdom on impatient idealists aching for heroism. It hardly seems respectful of the young to regard them as incapable of learning from history or from their more experienced seniors. Perhaps those most culpable were the adults on campus and off who, vicariously thrilled or simply intimidated by the revolutionary bluster of the New Left, gave it thoughtless encouragement.

Nathan Glick is the former editor of the U.S. Information Agency's Dialogue magazine.