"Guns don't shoot people; people shoot people," the National Rifle Association is fond of saying. It's a specious argument for not doing anything about the easy availability of handguns. But it does contain a grain of truth about the business of arms control. Whether you are talking about Saturday Night Specials or Pershing IIs, the principle is the same: It's the politicians, policy makers and, ultimately, the ruling figures who trigger wars.

That is no reason not to make every effort to get the international arms race under control. But the root causes of international conflict are worth keeping in mind when people in high places start talking about eliminating all nuclear arms. Whether it's Mikhail Gorbachev with his latest contributions to the Geneva talks, or Ronald Reagan with his Strategic Defense Initiative and its promise of an impregnable shield, the minute people start talking that way, you know that a deadly serious subject is not being seriously addressed.

To pretend that the world can ever be completely rid of the threat of nuclear weapons is to cheapen the arms- control debate. It does so by encouraging the soft-headed hope that there really is an alternative at hand to nuclear deterrence against nuclear or conventional war. The inescapable truth is this: for as far ahead as the eye can see, there is no alternative.

To begin with, there is no "erase" button in the mind of man; technology cannot be disinvented. There can be, accordingly, no insurance against the reconstruction of nuclear weapons -- even assuming the most meticulous dismantling.

The two superpowers alone have tens of thousands of nuclear weapons, all of them immensely more powerful than the two that ushered in the nuclear age. The French and British have independent nuclear forces in place. China, Israel, South Africa, India and perhaps other nations have the capability if not the hardware.

When Reagan and Gorbachev talk about negotiating an end to nuclear weapons, I think of Muammar Qaddafi and the impossibility of ever knowing for sure that nobody, anywhere, has a nuclear device tucked away.

You will know that an American president is serious about banning nuclear weapons only when he says he's prepared to trust Soviets not to cheat. We do not even trust the Soviets to honor the arms-control agreements we already have. You will know that Gorbachev is serious when he says he is ready to submit the Soviet society to the kind of intimate, on-site inspection that would make his ban-the-bomb proposal verifiable.

What would have had to happen by the turn of the century (which seems to be everybody's sense of a proper deadline) to give both sides the necessary confidence? The answer: a fundamental trnsformation of the ideological struggle between the United States and the Soviet Union -- something that is in nobody's crystal ball.

What we are really talking about when we talk of a world without nuclear weapons, then, is an unimaginable global state of grace. Failing that, even if we could stipulate that nuclear weapons (in Reagan's phrase) can be rendered "impotent and obsolete," it is impossible to make the same stipulation about so- called conventional wars. In their reservations about SDI, the Europeans make the central, practical point.

Against a hostile Soviet empire, the Europeans would be reduced to dependence on conventional deterrents -- and they would be heavily outmanned and outgunned. That's why the Europeans, the Japanese and others of our allies see nuclear deterrence as the only feasible alternative to a greatly increased conventional defensive effort entailing sacrifices they are not disposed to make.

So if one is serious about banning the bomb, the next question is: What else would be banned? Conventional weapons reduced large parts of Europe to rubble and inflicted millions of casualties in World War II. Tokyo was laid waste by fire-bombing before we got to Hiroshima and Nagasaki. Advances in the state of the art over the past 40 years make a conventional World War III not all that much more acceptable than a nuclear exchange to nations that have been the battlefield of two world wars.

We will know that the superpower advocates of eliminating nuclear weapons are serious, then, when they take up the question of eliminating chemical and biological warfare, or the laser beams and other high technology that would be developed for nuclear defense systems but which also have devastating offensive potential.

The real problem with talk about banning the bomb is not only that it is irresponsible to talk about something that isn't going to happen. The practical problem is that you wouldn't want it to happen -- unless by the time it did, the brightest dreams of the drafters of the Charter of the United Nations had all come true. But then, if the world had become that orderly, you wouldn't need arms control.