AT CLOSED hearings on the antiballistic missile legislation in the spring of 1969, a leading authority on nuclear strategy told a Senate panel that he thought it "most unlikely" that laymen could reach a rational judgment on the ABM. Indeed, he doubted that so abstruse a matter could ever be explained to those who were not already experts. Smiling sardonically, Senator Fulbright replied, "You go right ahead and try, Doctor."

That exchange captures the spirit of Gregg Herken's brilliant new book. A Yale historian, who coincidentally occupies the same office in New Haven that once housed the first of the nuclear theoreticians, Bernard Brodie, Herken demonstrated his own command of the field in an earlier study, The Winning Weapon. But he denies that "the subject of nuclear weapons is so technical and complex that it is best left up to the experts." Indeed, he believes the debate over nuclear war is not chiefly "over secret numbers, mysterious acronyms, or rival technical analyses," but is rather "a competition between deeply held and often unstated beliefs," especially about the United States and the Soviet Union. He quotes with apparent approval Paul Warnke's observation, "The experts don't have all of the answers -- and possibly not any of the answers," and he has chosen for one of the opening epigraphs of the book a sentence from Lord Salisbury: "No lesson seems to be so deeply inculcated by the experience of life as that you should never trust in experts."

In no sense, though, is Counsels of War a muckraking assault on "the doomsday scholars." Rather, it is an incisive, well- crafted account that draws upon hundreds of recently declassified documents; videotape chronicles of episodes like the Cuban missile crisis; rich archival sources such as the Brodie manuscripts at UCLA and memoranda in the Eisenhower Library; and more than 50 interviews, including three with former secretaries of defense and 22 with atomic scientists.

The focus of Herken's compelling study is the cluster of scientists and strategists on campuses, in government agencies, and at institutions such as Rand who, ever since Hiroshima, have been thinking about the unthinkable. Though they have been compared to priests roaming the Pentagon's corridors like "Jesuits through the courts of Madrid and Vienna," they are not conspirators, he insists, nor have they shared a common outlook. Neither can it be said that there is something perverse in their preoccupation with the bomb. "Most have been drawn to study it," he observes, "less out of what Joseph Conrad termed 'the fascination of the abomination' than in the spirit of Leon Trotsky's grim admonition that 'while you may not be interested in war, war is interested in you.'"

THOUGH there are any number of knaves in Herken's story (not least, the inevitable General Curtis LeMay who regards civilian casualties as a "bonus" of nuclear bombing), much of his book concerns men of principle who sometimes did even greater wrong because they could never bring themselves to resist the momentum of technology and unexamined political assumptions that were driving the great powers ever closer to mutual destruction. Not only despite, but also because of, the efforts of men of intelligence and good will, Herken notes, the power of destruction has increased since 1945 at an almost exponential rate. When a group of atomic scientists gathered in Sicily in 1982, one participant, recalling how badly the region had been damaged by 5,000 tons of explosives in World War II, remarked that the conferees were talking about a future war where 5,000 million tons might be dropped. And when the scientists who had constructed the atomic bomb returned to Los Alamos in the spring of 1983 for a reunion, the 86-year- old Isidor Rabi reflected sadly that "nations are now lined up like people before the ovens of Auschwitz, while we are trying to make the ovens more efficient."

ONLY occasionally does Herken intrude his own views, but certain axioms, stated or implied, leap out from his pages: No matter how many times experts cry havoc about nonexistent or exaggerated threats like the "missile gap" of 1960, they can be counted upon to come forth before long with yet another dire warning. No matter how many times an expert has been proved wrong in the past, he will pop up in a succeeding administration as a respected authority. No matter how nutty a multibillion dollar weapons program is, it will be justified as essential to demonstrate the national resolve. No matter how many times congressmen have been suckered by the argument that a reckless expenditure for an obsolete weapon is necessary as a bargaining chip, they will queue up early to be gulled by the same tale again. And no matter how many bombs are added to the nuclear arsenal, no one in authority in Washington will ever admit that there are enough. For whenever the government faces the embarrassment of an excess inventory of nuclear bombs, it merely increases the number of targets in the Soviet Union deemed essential to our safety. At the outset, there were 20 Russian targets; by 1979, 40,000.

Of all the developments Herken analyzes, the most disturbing is the willingness of high government officials to advocate either a "preventive war" or a strategy of fighting a nuclear conflict with Soviet Russia in the expectation of "winning." In the Truman era, those who favored dropping an atomic bomb on Russia or China, not as a defensive response but as an aggressive act by the United States, included the Navy secretry, the director of the Air War College, and Senator Stuart Symington.

No less worrisome is more recent experience. In 1976 Jimmy Carter talked often of his "dream" of eliminating nuclear weapons, but when a presidential review memorandum in 1977 estimated that in an all-out war with Russia the United States would suffer a minimum of 140 million dead, Zbigniew Brzezinski responded by seeking the capability to fight a nuclear war through to victory, a view that Carter soon embraced, and in 1979 Carter endorsed the MX, though "it was a nauseating prospect to confront with the gross waste of money going into nuclear weapons of all kinds." Little wonder that by the beginning of 1984 the editors of the Bulletin of Atomic Scientists had moved the hands of their doomsday clock to only three minutes to midnight.

STILL SCARIER has been the consequence of Ronald Reagan's election, which brought to positions of influence in Washington what one scientist called "the crazier analysts" -- those who believed in fighting a protracted nuclear war to destroy the Soviet Union no matter how many millions of lives it cost. Eugene Rostow, surely no dove, referred to this "group of ideologues" as "humorless" and "paranoid." The psychiatric metaphor is instructive. The head of one of the wartime labs at Los Alamos thought that future generations would regard what had happened since 1945 as "a virulent case of a collective mental disease," and, in truth, more than one reader of this book will be moved to ask whether some of the foremost policymakers of our own time are not loony.

Many of the quarrels over nuclear strategy in 1945, Herken points out, have a familiar ring today; yet something fundamental has changed: policymakers no longer feel the original sense of horror at the prospect of nuclear war. No one, he suggest, said this better than I. Rabi "It's obscene to get people accustomed to megadeaths," the Nobel laureate declared. The so-called "arms controllers" have "lost human sympathy. They lost an understanding of their own selves -- of their own meaning. There has been an atrophy of the imagination, a decline of the moral sense." That hardening of perception reminded one authority of the quatrain in Pope's Essay on Man:

Vice is a monster of so frightful mien,

As to be hated, needs but to be seen;

Yet seen too oft, familiar with her face

We first endure, then pity, then embrace.

Diffident though he is about imposing himself, Herken leaves no doubt about his convictions. He identifies himself with an early statement by Bernard Brodie: "Thus far the chief purpose of our military establishment has been to win wars. From now on its chief purpose must be to avert them. It can have almost no other useful purpose." We have been victimized, he intimates, less by the advance of technology than by the failure to examine our premises. Consequently, he calls for a new debate, not by the expts but by the American people, to address the issues "which the experts themselves have seldom raised, and never really answered." In an arresting conclusion to this very important book, he warns us that, before it is too late, we must all confront Clausewitz's inescapable question, "De quoi s'agit-il? -- What is it all about? What is it for?"