For 65 years now, Americans have been having a hard time with the dark side of the Soviet system. Are they such cheats and liars and murderers that we cannot do business with them? Are they merely ordinary despots with the ordinary habits of their breed? Or are they more sinned-against than sinning, so that the real enemies of Soviet-American harmony must be sought in our own ranks? All these views can be heard again as we contemplate the ugly evidence of yellow rain in Asia and the still-more- ugly possibility of a Bulgarian connection. Perhaps it is time to recognize that all three of our traditional attitudes are wrong.

Let us begin by assuming the worst: that the people who lied about missiles in Cuba are lying about yellow rain, and that the people who wanted Trotsky dead could want a non-Polish pope and let their wants be known to others. The present evidence on yellow rain is strong, and on the Bulgarian connection weak, but I am only assuming the worst, not asserting it. I do not see how we can honestly tell ourselves that such assumptions are preposterous, and not at all because "we are just as bad." It is true that even in our deeply different society there has been clumsy assassination plotting, but it remains wholly undemonstrated, and to me wholly implausible, that the presidents of that time ever ordered or approved such plots.

Soviet behavior in such matters is totally different from anything in our own gray past. Systematic deception, obsessive secrecy and ruthless political killing are all deeply rooted characteristics of the Soviet system. No one without blood on his hands, lies in his throat and terrible secrets in his head has ever come to the very top in communist Russia. Moreover, the guilt becomes collective by its collective denial. Forty years later, these men still cannot face the truth about Katyn.

But it is a long and wholly unjustified jump from these realities to the conclusion that we cannot do business with such men. They govern a great nation, and we must never assign to the Soviet people as a whole the offenses of their rulers. We are stuck on the same small planet, sharing the same thermonuclear danger. This reality alone is enough to require a strong and persistent effort to do most serious business with this unappealing regime.

The most dangerous moment we have had with them, the Cuban missile crisis, was caused by terrible failures of perception on both sides, and its peaceful resolution was the consequence not only of determination and strength, but of intense communication. Arms control negotiations have a much more complex history, but the common testimony of American negotiators of all persuasions is that when we are serious, the Soviets can be, too.

In less apocalyptic matters, we can find similar lessons: for example, we know from nearly 30 years of Austrian freedom that these men can keep their word when they find it in their interest to do so. Even the most sinister assumptions about chemical warfare and plots to kill cannot change these realities or our own interest in building on them.

But should we simply ignore the yellow rain and the possible Bulgarian connection? Of course not. The energetic exposure of outrageous behavior is our very best way of raising its cost in the eyes of these highly realistic calculators. Private citizens can and should hold Soviet feet to the fire of truth, as groups like the Helsinki Watch have done with great skill in the field of human rights. Governments can and should press their concerns where they can, though their standard of evidence must be high.

There are sensitive questions as to which official should say what and about whom, but our own sense of what is fitting should govern the answers to such questions. Soviet touchiness is another reality, but the character of Soviet propaganda-- which is just as much Andropov's doing as his own most solemn speech--allows us to adapt Adlai Stevenson's famous theorem: the time to stop telling the truth about these people will not come before they stop telling lies about us.

And now let's get serious in Geneva.