"Cowardly . . . bestial . . . beyond the pale of civilization" -- so went the familiar expressions of horror. The reflective rallying cries were all too familiar, as well: "The world community must unite to end this menace. . . . Those responsible must be punished. . . . There must be no place for terrorists to hide."

Never mind that none of this is of much practical use. Working through the shock of savage, indiscriminate killing is not an easy passage for civilized people. But you do eventually have to get to the hard part: What are we to make of the slaughter in the airports in Rome and Vienna last week? And what to do about it?

One thing to do is what the Reagan administration gives every evidence of doing, once having got past the obligatory prescriptions having to do with tighter security, stricter law enforcement, better intelligence, judicial processes. That's all useful. But it's more useful to see terrorism in all its awful complexity and to take each case as it comes. In this instance, that means a U.S. restraining hand on Israel, whose natural impulse is to lay all Arab terrorism at the doorstep of Yasser Arafat and the Palestine Liberation Organization -- and to lash back.

The administration is counseling that the finger may not point this time to Arafat, and that making him the culprit and the target for reprisal will put the fragile Middle East "peace process" at further risk.

Given the success of earlier U.S. cautions of this sort, only time will tell the effect of this one. No nation claims a better right to know the answers than Israel. And none, in fairness, has suffered so heavily at the hands of terrorism. That said, less and less does it follow that Israel has the only claim or the only interests or the right answers.

Those check-in counters were El Al's, which is to say Israeli. But the airports were in Italy and Austria. The Achille Lauro was an Italian ship hijacked in Egyptian waters, and the lone casualty was an American. The latest skyjackings were of TWA's Flight 847 and of an Egyptian airliner.

It cannot be coincidence that the United States, Italy, Egypt and Austria are all deeply identified with a point of view on how to bring peace to the Middle East. All have become players, major or minor, and have become caught up in the struggle.

They are entitled to question Israel's stiff refusal to find any distinction between the PLO and its various competing factions.

U.S. and Western intelligence agencies do recognize a significant distinction between Arafat's mainstream PLO element, Fatah, and an extremist splinter group called Black June and headed by Abu Nidal. He was expelled from the PLO more than 10 years ago and sentenced to death for an alleged attempt to assassinate Arafat. Both U.S. and Italian authorities find Abu Nidal's hand in last week's airport massacres.

If that's so, you come to quite a different theory of the case than that of Israel: you at least suspect that any inclination toward "moderation" in the Palestinian camp, centering on Arafat himself, might have been as much the target of recent terrorist events as the state of Israel. Peace has always been the enemy of Abu Nidal.

Interestingly, the Israeli government concedes much of the argument leading to this supposition, but rejects it anyway. "Okay, Abu Nidal is anti- Fatah," said Israeli foreign-ministry spokesman Avi Pazner a day or so ago. But "we have to take that claim with a grain of salt. I don't exonerate Arafat, because parts of his organization were responsible."

There's the nub of it. For Israel to make the same distinction as others make would be to play into the hands of those who, in the words of Israeli Defense Minister Yitzhak Rabin, "are trying to depict Arafat and his organization as those who wat peace."

When every terrorist act is answered by an Israeli attack on PLO installations, so-called moderate Arabs lose whatever moderating influence they have. Israel is thus spared the stresses of entering into the unknown of a "peace process" whose outcome it can't be sure of.

The obvious, all too simple answer, is to resolve the underlying Palestinian issues so that terrorism will go away. I don't believe that any solution would satisfy the Abu Nidals or that a successful "peace process" would put an end to terrorism in the Middle East.

But having no "peace process" guarantees an endless spiral of terrorism, retaliation and more terrorism. The evidence is writ large: in the Lebanese war with all the damage it supposedly did to the PLO; in continuing reprisal air strikes by the Israelis in Lebanon's Bekaa Valley; in the Israeli bombing of PLO encampments in Tunisia. All of this was done by way of retribution and punishment with a view to deterrence. Yet none of it deterred the carnage last week in Vienna and Rome.