A situation has come into being in West Beirut that resembles the situation that existed toward the end of the 1973 Mideast war. The resemblance is close enough, I believe, to justify some speculation on whether something better can come of this war for the Israelis and Palestinians than the grim aftermath that is being widely predicted.

In 1973, the Israelis, reeling at the outset of the war, recovered and were about to humiliate the Egyptians when the United States and the Soviet Union intervened politically. Egypt was thereby enabled to get out of the war with its confidence in its own valor and revival intact. This was the psychological prelude to peace with Israel. It also provided a basis on which the United States could insert itself into subsequent proceedings as something other than a patron of one side alone.

In 1982, the PLO took the Arab military lead for the first time and acquitted itself well. The PLO so claims, the Israeli military appears to agree, and plenty of third-party observers go along. True, the PLO was thoroughly outclassed and saved itself from complete pulverization only by retreating to the cover of West Beirut and raising a cry about Israeli disregard for civilian life. But the important point remains that the PLO fought well and--by means of another international intervention--averted the final defeat that would have washed out its earlier valor.

So it becomes possible to ask whether the PLO, like Egypt in 1973, may not have gained the confidence there is to be gained from striving bravely and from having one's effort and sacrifice appreciated. Is it conceivable that the PLO may be more of a mind--in one of its lobes anyway--to consider political options than it has been to this time?

Even if you regard that suggestion as wildly wishful, or simply as unproven, it seems to me important to note just how the PLO got to the surprising place where it is now. Far from being poised for the kill, the Israelis have suspended the war for negotiations with--through intermediaries--their hated adversary. Their agreed subject is the terms on which the PLO should make an honorable surrender-- that is, on which it should survive.

The terms being discussed, moreover, give the PLO a good deal more than what it could have extracted from an ultimate battle of Beirut. For this gift, the PLO, which earlier felt itself abandoned, owes much to those parties whose influence was lately brought to bear. Those parties include the Saudis and the United States. I have the impression that in their separate ways, and perhaps also in their cooperative ways, they finally saw an opening: to save West Beirut and then to get into the game in such a way as to win a voice in how it would be played out.

It remains to consider some intriguing words spoken this week by Menachem Begin about the conditions under which PLO soldiers might depart West Beirut. "We do not want to humiliate them," he was quoted as saying in the American press. "With their personal weapons, let them go in peace." He went on to explain: "They are lowly murderers . . . but they are human beings."

These words, seemingly so uncharacteristic, intrigued me. Why, after all, had Israel invaded Lebanon except to humiliate the PLO? The notion that people otherwise called terrorists could "go in peace," with weapons, seemed heretical. The whole basis on which Begin has denied Palestinians the rights he demands for Israelis is that the Palestinians--or at least the fighters among them--are only "lowly murderers" and not "human beings" as well. Was it a tired old man speaking late in the day, putting verbal trim on a concession being made for plainer reasons?

The full text contains a lot of rough and abusive words about the PLO, and it is quite possible that Begin was simply speaking in an ironic tone, coating his familiar contempt for the PLO in a bit of whimsy. So I would not make too much of his words. But . . .

The PLO has not come out for peace, but it is in the kind of circumstances, having fought well and averted disaster, that produced the first Arab-Israeli peace process. Menachem Begin has not accepted the PLO but, for the first time, I believe, he has spoken words that can be interpreted as respectful of the Palestinians. These are potential assets, fragile but not to be dissipated without first being thoroughly assayed.