CURRENTLY AND CONSPICUOUSLY in at least two neighboring Arab states, chronic Arab weaknesses offer Israel, itself hard pressed, the temptation of avoiding difficult choices. Probably few other governments in similar straits could resist the temptation. Yet it is almost certainly in Israel's true interest to resist and Israel is not resisting well.

In Lebanon, the play of factional policies has let Israel replace its now-departed invasion face along the border with right-wing Christian militiamen. It has done this despite a Security Council mandate to turn over the territory to U.N. peacekeeping forces. Israelis profess scant confidence in the United Nations capacity to bar Palestinian guerrillas from the border area. Yet the United Nations has surprised many observers in the performance of its demanding mission. Certainly it cannot be said - yet - to have failed. The role given the Christian militia is pure provocation to the Palestinians, a recipe for resumed civil war in Lebanon and for another Israeli intervention. Constantly complaining of insecure borders, Israel has a powerful interest in strengthening the border role of the United Nations. Nor does it need another argument with the United States, one of the few nations to respect the considerations of self-defense that led it to intervene in Lebanon three months ago.

In Egypt, the drift of Israeli-Egyptian negotiations, staggering economic difficulties and his own changeable nature have led President Anwar Sadat to reverse a hopeful experiment in democratization and to move against critics, journalists, political opponents and "communists" across a broad front. He has further tarnished his reputation as the hero of the Jerusalem initiative by threatening to return to war if the stalled negotiations fail. The Israelis cannot save Mr. Sadat from himself, and cannot be asked to. But it cannot conceivably serve Israel in the long run, though it may be a political convenience for the Begin government in the short run, to witness the unraveling in Cairo. When else, where else, how else does Israel expect to find the likes of Anwar Sadat as an Arab negotiating partner. Perhaps Mr. Sadat is faltering only temporarily and he will revive himself. But the Israelis could help enormously to revive him, and they would profit from it enormously.

Factionlism in Lebanon, deterioration in Egypt, Syria preoccupied by domestic and inter-Arab strains. Jordan taking the season off for the king's marriage, the Palestinians absorbed as usual in their own convolutions. With neighbors like these, the grandest temptation for Israel is to slow its own political dialogue and announce primly and with some crocodile tears that it is waiting for the Arabs to become fit to talk peace. Precisely to forestall this tendency, the United States has asked Israel to answer hard questions about its West Bank intentions. The hope is to draw Israel into responses that will make it possible, and unavoidable, for Egypt to return to direct talks. Signs of movement by Israel would, of course, make it easier to elicit signs of movement by Egpyt, and vice versa. That is the way to get the peace talks moving again, and that should be the common urgent goal.