I write at a moment when armed warfare has subsided in the South Atlantic and at least drawn down in the Middle East. Now the air over both, so recently filled with crisscrossing missiles, is filled with crisscrossing "lessons" being fired every which way from every side in answer to three main questions: What did the warfare show? What did it accomplish? Was it justified?

The first of these is a political question; it means: what signal did the combat send to other governments? Mrs. Thatcher has insisted from the start that Britain's willingness to fight constituted a warning to would-be aggressors the world over that, as they used to say on Gangbusters, crime doesn't pay. I wish I thought this were so.

The Falklands action certainly showed that Britain was serious about not being kicked around by Argentina and that it was willing to take risks and pay a price. But I think the implications are self-limiting: Britain sustained losses that make it extremely unlikely that its government could take on any comparable action for some time to come; and so far as many Class-A aggressors are concerned, let us say the Russians in Afghanistan or the Vietnamese in Cambodia, I don't believe they are especially chastened or affected by what happened.

The British did show that they are militarily skillful, brave and tough, something worth recalling to themselves and others. No one needed to be reminded of these things in relation to the Israelis, who have been in recurrent combat over roughly three decades. What has been most startlingly demonstrated in the Lebanese fighting is the thinness of support on the part of the Third World in general and the Arab countries in particular for the PLO as an organization. Surely the sunken cruiser of our precombat assumptions is (or was) this idea that there would be a terrific political outcry and reaction if the Israelis were to do what they have just done.

I certainly expected otherwise, just as I wrongly expected that the casualties in the South Atlantic would cause the British public to fall away from support for their government's action, rather than rally behind it as they did. A friend, Alexander Chancellor, editor of the British weekly, The Spectator, writes of his own changed feelings: "War has its own momentum to which nobody can remain immune . . . It has seemed fruitless to go on airing doubts about the wisdom of the whole venture when the obvious first priority has become to win the war. . ."

That of course has now been accomplished: what was most self-evidently shown in the Falklands and Middle East was that warfare can be conducted within certain limits and can accomplish certain ends. For the short term, anyhow, two countries fought for something they wanted and seem to have gotten it at what they, though not perhaps others, regard as an acceptable price. For all the suffering that was sustained, I'm afraid that in the minds of many they have given warfare a "good name."

We have crossed an ill-marked frontier here ourselves--from the question of what was conveyed to the world at large by all this action to the question of what was in fact accomplished. I am a little leery of the too-quick response that dwells exclusively on the short-term nature of the accomplishments and insists that over the long haul all the trouble will be back, because war "settles nothing." I sense in it my own instinct to cover some earlier misjudgments with this noble thought and also that it is only partially true.

This spring, war has settled some things. Certain of its consequences--most notably the revelation of the weakness of the PLO as an instrument able to command international support--have probably changed conditions permanently. But neither the plight nor the anger of the Palestinians themselves has been dealt with, any more than the political turbulence activated in Latin America by the Falklands conflict has been. New grievances, and, thus, conditions for new trouble to come have been created. The question is whether the victors will seize the opportunity to act magnanimously and try to make permanent political improvements, not just changes, in their relationships with those they have whipped.

The Thatcher government's ability to do this has evidently been limited by the number of casualties sustained by Britain's fighting men. Was their sacrifice or the sacrifice of a much larger number of Argentine men justified? We have such suspect and eccentric methods of deciding this question these days that no answer really has much moral credibility. We have become more skittish about warfare, more self-conscious about nationalism and more sensitive to the suffering fellow creatures whose role as "enemies" and whose direct responsibility for their leaders' actions against us seem tenuous at best.

So we count, or we measure comparatively against some arbitary expectation: 200 seems low, 900 seems high, only 19 lost, and so on. We don't know what we think any of this fighting is worth. Sometimes we justify it by irrelevant guideposts: it's not as many as were killed somewhere else, or the adversary government has done a lot of butchering itself. None of this answers the question. I would suggest that not a single British casualty will have been justified if the fact of their sacrifice becomes a real stumbling block to an otherwise attainable resolution of the conflict and a reason for prolonging it.

The Israeli fight was different--part of a decades-long struggle for self-preservation. But even some of Israel's most committed friends concede that the civilian casualties in and around the cities of Lebanon were horrendously, disproportionately high. Here again we reach the marshy soil of relative numbers. But that huge civilian death toll cannot begin to be justified. The destruction can only be made bearable, perhaps be redeemed, if the opportunity is seized now to try to reach a real peace with the Palestinians.

What seems indisputable as the firing dies down is that the violence represented failure, no matter which side prevails, that what you must do when it is over is what you should have done long before.