THE FINEST minds of this nation almost unanimously agree that deployment of an anti-ballistic missile system is logically and technically indefensible. Thus one might expect any debate of the issue to be an exercise in futility for the AMB'S defenders and an indulgence in verbal overkill for its opponents.

The Special Report on the ABM recently issued by the prestigious Center for the Study of Democratic Institutions is nonetheless a valuable document. The argument for the ABM is presented as forcefully and eloquently as possible--and then is carefully demolished.

The format of the book is a panel discussion, with Jerome B. Wiesner and Senator George S. McGovern arguing against development of the ABM and Donald G. Brennan and Leon W. Johnson, General, USAF (retired), arguing for it. The introduction by former Vice-President Hubert Humphrey is a reasonably effective though slightly rhetorical attempt to place opposition to the ABM in the context of general unclear disarmament. The epilogue, by Associate Justice William O. Douglas, is similar, arguing against the ABM from the standpoint of a man committed to total disarmament and the rule of international law. It is much less a comment on Justice Douglas then on the state of human consciousness to say that it is a very eloquent piece of hopelessly wishful thinking.

The Brennan-Johnson position has two major arguments. The first is that an anti-ballistic missile system would considerably reduce U.S. Casualties in the event of nuclear war. Brennan believes that an ABM deployment costing between $10 and $20 billion could reduce casualties from 80 to 120 million to something like 20 to 40 million; a reduction from almost half the population to less than a fifth. He further contends, incontestably, given the urban concentration of American industry and assuming his previous statistics are accurate, that the nation's loss of productive capacity in a nuclear exchange would be reduced by a greater amount. He concludes that the ABM would make the difference between enormous though withstandable losses and the destruction of the United States as a coherent society.

THE SECOND argument in favor of ABM is that we dare not permit the Soviets to "take the lead" in building an ABM system. To do so, insist Bernnan and Johnson, increases the probability that the Soviets will feel they are in a position to destroy the United States with acceptable damage to themselves.

Wiesner disposes of the first argument in short order. The figures Brennan cites are highly suspect on technological grounds, and he admits they are applicable only "assuming that the Soviets do not make a major increase in their offensive forces in response to our improved defense." The ABM would be the most incredibly complex electronic-mechanical system ever built, with all the fallability such complexity implies. The ABM's reliability could never be tested under conditions approximating those of a nuclear attack, simply because there is no way of simulating all the conditions of a nuclear attack. For example, a radar system control the trajectories of the ABMs. We know that radar is affected in strange ways by nuclear explosions, but that is all we know. To accurately test the effectiveness of the ABM's radar system under actual attack conditions, we would have to explode large nuclear weapons all over this continent.

But, as Wiesner points out, even if the system works as well as the Pentagon's feasibility studies predict, we have no assurance that the Soviets will be content to maintain a static offensive force. There is every reason to believe the Soviets will increase their offense if we build an ABM system, just as we did when we discovered them deploying an ABM system around MosCow. So long as it costs more to purchase an ABM than it does to build the offensive weaponry to offset it, the ABM is tenable only if your are willing to spend some multiple of your opponent's offensive budget.

But, Brennan replies, that argument presumes that the U.S. and the Soviet Union will maintain their present definitions of the minimum loss they are willing to inflict upon each other.

They rejoinder is that they are about as likely to do that as they are to resist the temptation to build ABMs; certainly no more, probably a good bit less.

SENATOR McGovern uses the history of U.S. ABM research and development to devastate the second argument. It takes a considerable amount of time, about five or six years, to test and deploy any ABM system. Because of the complexity of the system, an ABM system is not something the Soviets could erect and use without ample time for the U.S. to construct a similar defense. We seem to have learned quickly about the system the Soviets were deploying around MosCow. Assuming the CIA is equally efficient in discovering a nationwide deployment of an ABM system by the Soviets, we would not be subject, as General Johnson thinks, to "that Soviet nuclear blackmail we have avoided for the past twenty years." We would "lose" only several months. Given the much greater productive capacity of the U.S. economy, that is a risk we can easily afford to run; in fact, only the most picayune or the most hysterical alarmists would dignify it by calling it a risk.

Though formulated more thoroughly and precisely than they have been in a great delay of the public debate, the arguments are still familiar. So it is a more-than-welcome suprise to see Senator McGovern and Humphrey mention, though not directly discuss, the real reasons why the ABM is being built.

The first has to do with the mentality of a military establishment. It is a truism that soldiers exist to fight--and win--wars. Major "conventional" conflicts are unlikely, if only because they would quickly become nuclear once any party thought it was losing, the U.S. is inept at combating guerrilla units, and major nuclear was is, at the moment, strategically unacceptable. There just don't seem to be any kinds of wars the U.S. can win anymore. The obvious question becomes: What do we need soldiers for? or, at least, what do we need so many soldiers and weapons for?

That is the sort of question that is bound to make a professional military man more than a bit nervous. And whether it knows it or not, the American military has been reacting to this question. The only way to get back to a place where its existence is justified is to somehow create a situation in which a nuclear war can be "won."

ROBERT McNAMARA believed precisely this, says Humphrey:

The most dangerous thing in the world is a state of mine--the belief among powerful men on both sides, in the face of all the horrendous evidence to the contrary, that somehow the scientists will yet fins a way to employ nuclear weapons so that military men may again win a war.