Every once in a while, someone calls me with a really terrific story--a story so terrific, so deserving of the seldom-heard cry "stop the presses" that that is precisely what I want to yell. Only I know better and so I check out the story and almost always find that things are not what they first seemed. Nothing ruins a good story like thorough reporting.

It is the same with the concept of evil, as in the term "evil empire." President Reagan has used it to describe the Soviet Union and it was trotted out again by others in the aftermath of the downing of the Korean airliner. There is an I-told-you-so quality to these echoes of the president's statement, and then a pause while the speaker waits to be told that the president has been vindicated.

But once again thorough reporting reveals complications. What once looked so simple--a massacre in the skies--now looks not quite so black and white. The essence of the charge remains, of course, and it is compounded by the way the Soviet Union lied, but after that, things get murky.

The entire incident could have been a botch--not a rational decision. It could have resulted from the panic of an area commander, what Tass called a "command post." It could have resulted from the military pressuring a new and insecure civilian government. It could have been the reaction to the 1978 incident in which another Korean airliner wandered 1,000 miles into Soviet territory and made the Russian military look like monkeys.

These are possible explanations, not excuses, because the act itself was inexcusable. But whatever the explanation, pure evil does not seem to be one of them. Instead, the act resulted from some characteristic of the Soviet system--as does the failure to come clean about it. All of it, what is known and what is merely surmised, is open to analysis. It cannot be condoned, but it can be understood, and what emerges is not a picture of evil and raw strength, but incompetence and weakness--at least insecurity. Secure nations do not panic and shoot unarmed airliners from the sky.

Despite the administration's attempt to paint a picture of the Soviet Union casually wasting human life, Reagan's actions say something else. The president went on television, denounced the Soviets but pulled his punches. No curb on grain sales. No suspension of arms control talks. No re-institution of the Siberian pipeline embargo. It was as if the White House was tacitly acknowledging that evil was not the total explanation, that possibly it was something else--certainly not virtue gone astray, but not evil either.

Conservatives were disappointed, but the American people apparently were not. The White House reports no avalanche of protest calls. Capitol Hill seems solidly in the president's corner and even The New York Times, up to now no fan of the president's, editorially told him he was doing the right thing. You can't rely on anyone anymore.

What is striking here is that America seems capable of both outrage and pragmatism--of simultaneously saying that what the Soviets did was despicable, and yet certain processes must continue. It is a cold, professional assessment, one that recognizes that we are locked into a small world with another superpower and we, like they, must deal with the ultimate question of war and peace. Anything else, while important, even compelling, is secondary.

And what is also striking is that this pragmatism is shared by the president. He made sure that the really important business between America and Russia would continue. This is not the stance of a man who believes the logic of his own rhetoric. It would be folly, after all, to negotiate with true evil. It would be a double folly to negotiate with it after it has committed an evil act.

All this means that both we and the president have come a long way. History--the Iran hostage crisis, Poland and Afghanistan--has taught its lessons. We now know both the value and the folly of symbolic acts and know, further, that to label a country "evil" is not merely a statement of outrage, but an admission of ignorance.