Since the dawn of the nuclear age mankind's survival has rested on the novel concept of deterrence.
Deterrence as such is not new, of course. The phenomenon has existed ever since (one assumes) the first cave man averted a raid on his hearth by holding a bigger stone aloft than the rival cave man wielded.
What is new is the central importance of deterrence. In the past it didn't matter so much to the human race if deterrence broke down and disputes over home and societal values and national grandeur were resolved by battle rather than by one side's timely retreat. One person, one family, one generation of young men, even, might be slain. But others would survive, return to normal lives, and procreate for posterity.
The hydrogen bomb changed this. Scenarios for an all-out nuclear war project tens of millions of deaths in a few moments. Mankind can no longer afford to have deterrence fail.
That axiom is simple. Its implications are not. They fly in the face of conventional military and political wisdom.
The first step in comprehending the peculiarities of deterrence came with the American debate about whether any defense was possible against the atom bomb. President Truman thought in 1945 that ''every new weapon will eventually bring some counter defense to it.'' So did the United States Navy. The US Air Force was skeptical.
The Air Force proved to be right. Defense was difficult enough against planes carrying nuclear bombs. (Unless a defender destroyed 100 percent of incoming aircraft, he would still suffer devastation.) And defense became impossible against missiles that could fly from one continent to another in minutes. (At first no technology existed to protect missiles; by now some partial technology has been invented, but its ''cost effectiveness'' means that it is cheaper for an assailant to add one more warhead than for a defender to add sufficient interceptors to stop the incoming warhead.)
Once both the United States and the Soviet Union had nuclear weapons, then, the first premise of security planning came to be the unavoidable vulnerability of both superpowers, and especially of their major civilian cities, to any attack. The corollary quickly came to be that the only possible ''defense'' was retaliation.
The aggressor cave man had to be deterred from ever throwing his first nuclear rock by the certainty that if he did so, a second nuclear rock would flatten him, too.
As early as 1946, Bernard Brodie, a pioneer nuclear strategist, drew the conclusion: ''Thus far the chief purpose of a 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.''
This hard nuclear truth established itself - not without resistance - after the Soviet Union broke the American monopoly on the atom bomb in 1949, and especially after both sides got the even more terrible hydrogen bomb in 1952-53. It was after the thermonuclear explosions that Winston Churchill drew the further conclusion of superpower stalemate and therefore of paradoxical enforced peace: ''Then it may well be that we shall by a process of sublime irony have reached a state in this story where safety will be the sturdy child of terror, and survival the twin brother of annihilation.''
President Eisenhower's secretary of the Air Force, Donald A. Quarles, agreed. War was now an ''unthinkable catastrophe,'' from which ''neither side can hope by a mere margin of superiority in airplanes or other means of delivery to escape.''
In part Secretary of State John Foster Dulles's doctrine of massive retaliation acknowledged this stalemated condition. In part it did not. Nuclear weapons were to be used only in response to an attack; and deterring wars, not winning them, was the main objective. But Dulles preached the need to ''seize the initiative'' and rejected any restrictions on targets or weapons. His policy envisioned the firing of American nuclear weapons in reaction either to nuclear or conventional incursions in various trouble spots around the world.
In practice, however, the United States refrained from ever repeating Hiroshima and Nagasaki. And in only one part of the globe did the threat of a US nuclear response to a conventional attack become fixed policy: in Western Europe , America's top defense priority abroad and an area in which the US felt a specific need to compensate for Western inferiority in conventional weapons and manpower.
In the early years there was no comparable Soviet adjustment to the new nuclear world. Stalin was far too rigid to budge from the Soviet Union's ponderous Permanently Operating Factors that had finally repulsed Hitler's legions. Besides, the initial US monopoly on and subsequent clear superiority in nuclear weapons meant that the only profitable psychological and political approach for Moscow to take was to deny that nuclear weapons had changed anything. At Potsdam, Stalin treated President Truman's news about America's novel A-bomb with nonchalance. This indifference to the impact of nuclear weapons remained official Soviet policy until Stalin's death in 1953.
Under Nikita Khrushchev the Soviet nuclear debate did begin. In a pattern that was to become the norm for the nuclear era, however, the Soviet debate was nowhere near as radical as the American one. It never sought to set up a fundamentally new analytical framework for war and diplomacy.
To some comrades, of course, Khrushchev's innovation that wars with capitalist states were no longer inevitable was a shocking revision of Stalin's version of Leninism. But even Khrushchev's revision stopped well short of the growing Western conviction that there could be no winner in a nuclear war.
Khrushchev did come close to this admission in retorting to Chinese charges of Soviet cowardice in not threatening ''paper tiger'' America with sputniks. He also came close to postponing indefinitely the ultimate world victory of Marxism-Leninism. But throughout Khrushchev's last and Brezhnev's first years in office, the Soviet proviso would remain that if nuclear war should break out, then capitalism would be destroyed, and the (Soviet-style) socialist survivors would go on to build the brave new world.
Furthermore, this ideology of the inevitable world victory of the Soviet-led socialist camp endures to this day - along with the solemn duty of the Kremlin to promote this victory, by arms if necessary. This ideology is in stark contrast to the Western premise of a nuclear-decreed military stalemate, and to the West's model of world pluralism, stability of the status quo, and the imperative of not upsetting the existing international order by force.
In the US, the second stage in the evolution of thinking about deterrence arrived with Defense Secretary Robert McNamara in the heady years of John F. Kennedy's presidency in the early 1960s.
McNamara completed the wresting of nuclear strategy away from military commanders to civilian academics. He became fascinated by the idea of limited wars (including limited nuclear wars) and pushed development of battlefield nuclear weapons. And, in the element with the greatest relevance for arms control, he eventually wrote a definition of how many nuclear weapons were enough in the approaching world of nuclear plenty. His thesis was called ''mutual assured destruction'' and was dubbed ''MAD'' by its detractors.
MAD (the nickname was defiantly adopted by its proponents as well) was based on the distinction that Albert Wohlstetter, a think-tank analyst, first drew in public in 1959 between first and second strikes. A first strike was the opening shot of a nuclear war, and was specifically directed against the nuclear weapons of the enemy with the aim of wiping out his means of retaliation.
A second-strike force was one that could survive such an incoming first strike and still cause unacceptable damage (even if only to cities) in its own return blow.
For McNamara all that was necessary or desirable for purposes of deterrence was an assured second strike. A first-strike force would be superfluous - and, American strategic thinking increasingly believed, dangerous. It would add nothing to American security. It would simply feed the Soviet feeling of insecurity, induce a jittery trigger finger in Moscow, and thus add to ''instability'' - that bugaboo of deterrence.
An assured second strike, on the contrary, would promote the ideal of stability. By being able to ride out a first strike it would allow time for calm assessment of a real or suspected attack before any decision were made on a response. It would reduce ''use 'em or lose 'em'' pressure for a policy of overhasty ''launch on warning.'' It would leave time to distinguish between a deliberate adversary attack and, say, an accidental launch or a deceptive firing by some third nuclear state.
In this atmosphere the new concept of ''arms control'' sprang up.
Arms control, unlike deterrence, had no real historical precedent. It differed from previous attempts at ''disarmament'' because it didn't really seek to end the arms race, nor even primarily to cut numbers of weapons. Instead, it accepted the arms race as a given, and sought to manage it, to render it less explosive, by maintaining a stable balance that neither side would be tempted to break out of. If stability might be greater at higher rather than lower levels of weapons (by making any cheating or even surprise attack so marginal that it would not destroy the effective balance and therefore would be unprofitable), then so be it.
Arms control also differed from earlier disarmament efforts in its fundamental analysis of the arms race. Arms controllers rejected the disarmers' vision of any arms race (whether of nuclear missiles or of dreadnoughts) as the source of tensions between rival nations. They rejected as well the disarmament debunker's vision of any arms race as the wholly dependent manifestation of some other hostility.
To arms controllers, the arms race was indeed an aspect of some more basic clash of perceived national interests. (Canada, after all, doesn't get alarmed by any US buildup of missiles or tanks.) But an arms race - especially in a thermonuclear age of unprecedented penalty for misjudgment - could dangerously fuel fears and lead to overreaction, miscalculations, and possibly a disastrous war that no one really intended.
The new arms-control theory, therefore, tried, in the mathematical and ''systems analysis'' jargon that came into vogue, to write rules for a ''non-zero-sum'' rather than a ''zero-sum'' game. The latter term described a contest in which one player's gain was necessarily the other player's loss - the traditional view of any arms race.
The innovation was to be a contest in which some moves might be seen to benefit both players, with a premium placed on certain aspects of cooperation (such as, for example, survival).
To conventional military thinkers, all this was highly suspicious. It was bad enough to say in the abstract that no defense was possible against nuclear weapons. It was worse categorically to renounce both defense and victory in one's very force planning, and it was the greatest heresy of all to think that the Soviet Union should be encouraged to develop an invulnerable second-strike capability. Such an elevation of the fact of mutual vulnerability into a principle of unilateral relinquishment of a first-strike option defied all common sense.
Furthermore, the value-free neutrality inherent in treating both the Soviet Union and the US as equivalent players in a game - and the whole view that the arms race itself might be even more of a danger to Americans than the Soviet threat - seemed to belittle the differences between the two societies that Americans were so proud of.
McNamara prevailed over the objections. The ''balance of terror'' was acknowledged as the state of mankind in the second half of the 20th century, and stabilizing this balance of terror became America's policy goal.
As Prof. Thomas Schelling of Harvard University described it, the world was now witnessing ''a massive and modern version of an ancient institution: the exchange of hostages'' as a guarantee of good behavior.
The gravest test of the balance to date came with the 1962 Cuban missile crisis, when Khrushchev tried to sneak nuclear weapons into Cuba to compensate for the developing American superiority in intercontinental missiles. (The disparity resulted because the two countries had gone in different directions in the first few years of the missile age, with the US concentrating on intercontinental range, the Soviet Union on intermediate range, with Europe as the target.)
In retrospect, the Cuban missile crisis was both alarming and reassuring. It was alarming in the immediacy of the threat of ultimate resort to nuclear weapons, and reassuring in its resolution without that resort, as Khrushchev withdrew his missiles.
The scare helped prod the superpowers in the direction of arms control that the analysts were exploring. The two superpowers agreed to ban nuclear testing in the atmosphere and to prevent nuclear proliferation to other countries. They set up a hot line so that each side could avoid miscalculation in crises and reassure the other about what it was doing or not doing. They devised rules for preventing accidental and unauthorized use of nuclear weapons and formalized these in the Measures to Reduce the Risk of the Outbreak of Nuclear War.
Most significantly, by 1972 the two nations for the first time put a mutual ceiling on their offensive nuclear launchers in SALT I, and agreed not to deploy more than a minimal antiballistic missile defense.
SALT I, it seemed, corroborated the perverse new peace based on invulnerable nuclear weapons and vulnerable civilian populations. As Laurence Martin, vice-chancellor of the University of Newcastle, put it, deterrence was enthroned and widely regarded ''as the crowning achievement of postwar strategic thought.''
But by 1981, when Professor Martin uttered these words in the BBC Reith Lectures, he was already using the past tense as a prelude to discussing the ''severe limitations'' in this theory of nuclear deterrence.
Next: The politics of nuclear weapons Suggested further reading:
The Evolution of Nuclear Strategy, by Lawrence Freedman. London: Macmillan. 1981.
Nuclear Weapons and World Politics Alternatives for the Future, by David Gompert et al. New York: McGraw-Hill. 1977.
''Nuclear Strategy: the Case for a Theory of Victory,'' by Colin Gray. International Security, Vol. 4, No. 1, summer 1979.
The Nuclear Revolution, International Politics Before and after Hiroshima, by Michael Mandelbaum. Cambridge, England: Cambridge University Press. 1981.
Strategic Thought in the Nuclear Age, Laurence Martin, ed. Baltimore: Johns Hopkins University Press. 1979.
New Directions in Strategic Thinking, Robert O'Neill and D. M. Horner, eds. London: George Allen & Unwin. 1981.
The Effects of Nuclear War. Washington: US Office of Technology Assessment. Washington. 1979.