John Hersey, whose report on Hiroshima a whole generation still recalls, ends his update, "Hiroshima: The Aftermath" (The New Yorker, July 15), with laconic reflections on one of the hibakusha or "explosion-affected persons." Kiyoshi Tanimoto "read in the papers that the United States and the Soviet Union were steadily climbing the steep steps of deterrence," Hersey writes. "He lived in a snug little house with a radio and two television sets, a washing machine, an electric oven, and a refrigerator, and he had a compact Mazda automobile, manufactured in Hiroshima. . . . His memory, like the world's, was getting spotty."

One hesitates to deny a survivor his chosen consolations. But is the world in fact forgetting the horrors of the bomb, as Hersey's references to the seductions of national armaments and individual comforts suggest? Is it not just as conceivable that here people have made a sensible and necessary decision to cope with difficult circumstances -- to care for their defenses and, meanwhile, to get on with their lives?

There is a common view that people who are not caught up by a daily sense of the fragility of the nuclear peace and the paramountcy of disarmament -- and, it sometimes follows, the madman potential of Ronald Reagan -- are victims of a wrongheaded, escapist and perhaps militaristic sensibility: "psychic numbing," the phenomenon is sometimes called. Some people feel this way in flashes, if not in longer spells, and it brings them to a point of emotional quivering and relentlessness in political controversy.

I have known some of those flashes, but something else troubles me more regularly. It is not so much the sharp premonition that we all are playing carelessly on the brink of nuclear devastation as the queasy feeling that in nuclear matters we do not have adequate control of our destiny. But it is more akin to the feeling I have about the narcotics problem, the budget deficit and other wild beasts that we somehow domesticate and make part of our lives. How can mature people allow these things to happen?

How can someone who observes the arms buildup and the political tensions not feel we are playing on the brink of nuclear disaster? Along with the negatives, there are some positives. Over 40 years, the nuclear powers have shown a readiness to learn both the mechanics and politics of restraint in the actual handling of their weapons and their crises. Public opinion, good sense and self-interest have forced them to. That no further bombs have been dropped is no reason to relax, but it would be foolish to deny the instruction that comes from understanding why they have not been.

These days, for instance, there is a new wave of attention in and out of the government to the procedures and apparatus of nuclear command and control. The onset of more accurate warheads inevitably provoked new consideration of nuclear war-fighting strategies; keener attention then started flowing to the possible "nuclear winter" effects of applying these strategies. You do not have to be sanguine about the eventual results to see that public opinion and internal debate have worked to draw the American and Soviet governments, in their separate ways, into arms control talks.

The 40-year reviews of Hiroshima are themselves instructive. They have focused on the situations -- this includes all situations since the two bombs dropped in wartime -- when the use of nuclear weapons was considered more or less seriously but was ultimately rejected. In the last analysis if not always the first, governments have been responsible. In the consensus view, which, granted, may or may not finally be guiding, the single accepted function of nuclear weapons remains deterrence.

Nor, in asking why the nuclear peace has held, can Hiroshima itself be ignored. The great purpose of dropping the bomb was, I believe, to win the war quickly and cheaply, and it accomplished that purpose, producing a Japanese surrender within days and saving the many American lives and the far greater number of Japanese lives that would have been lost in an invasion of the home islands.

But a great effect of dropping the bomb was to demonstrate nuclear power. The demonstration played into the calculations by which the great powers have kept their rivalry on the safe side of direct confrontation in the 40 years since; in every instance except Cuba, by a large margin on the safe side. This conclusion is rejected by those who feel that the bomb, posing a historically new threat to the life of the planet, was born in sin. It seems to me the practical essence of living with the bomb.