The world weeps over the Soviet downing of an unarmed South Korean commercial airliner last week. It weeps because of the personal tragedy, the needless loss of so many innocent lives. It weeps, too, out of frustration and anger that the Soviet Union has again acted in such uncivilized, brutal manner. Can the West, it is asked, associate and do business with a nation that seems to scorn every code of decent, humane behavior?
The question needs careful thinking through. For, while there is an understand-able urge to want to punish the Soviet Union - and some international action is surely appropriate - unwise retaliation could in the end make matters even worse. To cut off nuclear arms talks, for instance, or to cancel the recent US-Soviet grain deal as some American lawmakers suggest might provide a sense of self-satisfaction. But it would also harm the West's interests. President Reagan is to be commended for a measured, farsighted response that seeks to avoid sharp confrontation.
Americans in particular have a tendency to want quick solutions to international problems, including the problem of coping with a powerful communist adversary. Yet the fact is, it could take years, perhaps decades, before the totalitarian system of the USSR changes enough to make friendly association possible. The shooting down of the South Korean airliner is another stark illustration of how different the Russians are. They are a people with different values, a different outlook, a different historical background. Their behavior and experience cannot be measured by that of the United States or Great Britain.
There is no excuse for the violent attack on the Korean airplane. But it may help to understand that the Soviets have a fixation about security and about their borders that leads them to excessive measures of ''self-defense.'' They also have a fear of showing weakness. In a similar air incident in 1978 a South Korean Boeing 707 strayed many hundreds of miles into Soviet territory before the Russians fired on it, causing it to make a forced landing. Were they perhaps remembering that incident - and the slowness of their reaction - and determined not to let it happen again? There is also the matter of the Soviet military mentality which sees orders in black-and-white terms and makes no leeway for ''humane considerations.''
While all of that is profoundly sad, it must not blind the outside world to the urgency of working for stable relations with the Soviet Union. The Russians do not have to be admired. However, it would be self-defeating for the West to stop trying to do business with them. It is in the mutual interest that the superpowers bring their nuclear arms competition under control - not only to reduce the danger of armed conflict but to help provide a climate in which such tragic border incidents can more easily be avoided. East-West trade is also in the mutual interest - because it yields benefits for both sides and because it forces the Soviet Union to live up to certain international standards.
Over the course of time it can be hoped there will be changes for the better in the Soviet Union, that the Russians will become less xenophobic and insecure, less aggressive. They themselves are victims of centuries of autocratic rule that prevents them from realizing their potential and making a constructive contribution in the world. That, too, is tragic. The West cannot morally tolerate the terrible misdeeds of the Soviet Union. But in calculating its reaction, it must count the long-term cost. Peace demands that East and West learn to live together, however uneasily.