As tricky as the political equation is in Lebanon, the human equation is trickier, and more tragic, and likely to play back into the politics.

Its prime element is that many thousands of civilians, both Lebanese and Palestinian, were killed and injured in the Israeli invasion. Israelis explain the toll as a consequence of the PLO's deliberate disposition of its forces in civilian locations and of the "natural" accidents of war. The carnage would have been much worse, they insist, had the Israeli army not taken the pains it did, often at considerable loss of military opportunity.

There is a limited truth to such explanations, but only a limited truth.

It is part of Israeli strategy to give the local population a powerful incentive to stop providing even reluctant sanctuary to Palestinian soldiers. Thus does the indirect punishment of civilians become something more than the regrettable byproduct of direct assaults on guerrillas. The rationale is that if civilians pay a certain price in the short run and draw the proper conclusions and help freeze out the guerrillas, they will fare much better in the long run.

You could call this approach Realpolitik, lancing a boil. It stirs what hope there is to reconstitute a peaceful Lebanon and to reduce Palestinian terror. But there remains another name for the use of violence for purposes of political intimidation: terror. The tension between the two definitions of Israeli policy is unavoidable.

No less than any other embattled group, Israelis dehumanize their adversaries. One evident result is the Israeli army's sometimes wanton use of its firepower. For every actual or would-be civilian victim of Palestinian operations, there have now been perhaps scores of victims of Israeli operations. The disproportion deeply embarrasses Israeli diplomacy, as it should.

Israelis point defensively to recurrent Arab mass slaughters of Arabs--Lebanese estimate (and Israelis dispute) that 10,000 civilians died last week, against perhaps 70,000 dead in Lebanon since 1975 at Arab hands. They ask in effect whether Arabs in their collective, impersonal aspect put any more of a premium on Arab lives than Israelis do. But this defense ignores the central tribal fact: family members are permitted lapses not allowed outsiders. And it leaves the Israelis abandoning their claim to occupy a higher moral ground than Arabs--a claim at the heart of their appeal for a special Western tie.

Then there are those who point out that the United States did the same in Vietnam, or worse. Let us welcome the humility that comes from history. But let us look closely at the history. Like the United States, Israel is a democratic country with a public demanding that conduct be reasonably consistent with a humane moral code. American conduct in Vietnam persuaded many Americans that their country had trampled on its code. There followed a decade or more of internal convulsion and some not inconsiderable external enfeeblement. I am not talking here about anything so precious, and so decidedly Israel's own business, as the quality of its soul but of its capacity to get along in an unforgiving world.

Nor can it be a matter of indifference to a country in Israel's exposed circumstances that in Lebanon the distinction between civilian and military victims of conventional military operations was rubbed finer--and by Israelis--than in any of the Arab-Israeli wars since 1948. You can say that the civilian-military distinction in the Mideast tends to be arbitrary. Do you really want to say that? This time the battlefield was Lebanon. The next time?

In the last two weeks, I have heard repeated expressions of anger and despair from Americans mourning Arab dead. These mirror the expressions I have heard in the past from, alas, other Americans-- never the same--mourning Israeli dead. In both cases, the feelings reach to something beyond the loss, anguishing as that is. The extra edge is the conviction that one's losses are not being properly registered by an American moral chorus, including government and press.

A proper mourning there must be, but that is not enough. The residual source of the terror and the tension in the Arab-Israeli world must be treated by providing the Palestinians a home to match the one Israelis already have. Otherwise, more terror and more tension are only a matter of time.