THESE DAYS there is a kind of taboo against contemplating in too fine detail what nuclear warfare might be like and how it could most efficiently be conducted and who would stand under certain conditions to lose or save what. The reason for the vaguely magical and superstitious injunction against such talk is that it can make the prospect of nuclear war seem to those in charge of preventing it, somehow, both inevitable and manageable. And it can also scare a prospective opponent into rash acts of his own, giving him the idea that the other side is figuring to start such a war. But clearly these forbidden subjects are also subjects a responsible government needs to give some very detailed thought to. And therein lies a fundamental problem of our government in a broad range of foreign crises just now and in our continuing nuclear relationship with the Soviet Union in particular: how to prepare to meet prospective threats to the nation's security without, in the very act of preparation, being provocative.

Government contingency plans have always had an unfortunate way of being received, once revealed, as a bald assertion of policy and intention. A hot example of this perennial trouble-causer turned up in a Sunday story in The Post ("Thinking the Unthinkable: U.S. Eyes Bombing Russia Without Wiping It Out"). The "eyeing" described in the headline was being done by a bunch of consultants whom the Pentagon had engaged to make some "what-if?" studies concerning how the desolate human and political landscape might look after various kinds of nuclear warfare had occurred and what the United States could reasonably expect to achieve in any such conflicts. Merely to say as much, you will note, is immediately to sound, if not bloodthirsty, at least slightly deranged. And yet -- we insist on it -- it would be wildly reckless for the people who preside over our national arsenal and our national strategy not to address seriously the questions of what we think that arsenal is for, in the event deterrence fails, and what, grisly as it might be to meditate on, the outcome of various kinds of nuclear combat might be.

For concerned and involved political people, it seems to us, the right response to all this should be, first, a warness about confusing our own government's intentions with its attic-ful of "what-if?" studies. Next should come an understanding that such confusion may be easier for people in the United States to avoid than it is for, say, the Russians; we have never been much on all those "mirror-image" explanations of U.S.-Soviet conflict, but you do not have to see the Soviets as innocent victims of anxieties created by the American military to appreciate how fine the distinction between theory and intention may look to people when it's their own obliteration that is being considered.

Finally, from musing about how Russians may read such stories about "bombing Russia without wiping it out," one should get an important corrective slant on those hyped-up translations of Russian nuclear planning against us that are increasingly being fed into the arms debate. Never a Soviet marshal comes forth with some hideous contingency plan or speculation that it doesn't find its way into our pantheon of national scares: they intend to do this... or that... As this country heads into a prolonged and probably strained and nasty national argument over nuclear arms and right relations with the Russians, it has never been more important to keep these fundamental distinctions in mind.