The fuss at the United Nations conceals the true dimensions of the crisis building in the Middle East. Its basis is that the Camp David agreement, once thought of as the single diamond in President Carter's crown, may be turning to paste, and nothing is now available to replace it.

Camp David is staggering from three blows. Carter delivered the cruelest by approving a Security Council resolution that prejudges the central issue -- the "final status" of the West Bank -- that under Camp David was to be negotiated by the parties over a five-year period once "autonomy" had been established.

In a vote whose real effects are scarecly softened by the administration's subsequent about-face, the United States publicly accepted that the land in question is "Palestinian" and that Israeli settlements should be dismantled -- and that Jerusalem should be redivided.

Thus has the administration invited all Palestinian and Arab bargaining from here on in to start from those positions. Why would any Palestinian negotiator now agree to "pay" Israel, in, say, recognition and security -- which is the way Israel should be paid -- to retreat to positions that Israel's sole patron has already yielded? This goes to the fundamentals of negotiating. How could Cyrus Vance not have understood something so elementary?

The second blow to Camp David is, of course, the one Menachem Begin has been delivering by his West Bank settlement policy from the day Camp David was signed. Inexcusably, Jimmy Carter never nailed Begin down on this issue, so he has been an accessory to an Israeli policy that even while pledged formally to hold open the "final status" of the West Bank, has steadily comprised that pledge. The administration only compounded the damage by its ham-handed catch-up effort at the United Nations.

Begin's response was to replace the departed foreign minister, Moshe Dayan, a man promising imagniative exploration of the possibilities lying between the lines, with Yitzhak Shamir, a neanderthal who voted against both Camp David and the peace treaty with Egypt.

The third blow is currently being prepared by the West Europeans, led by the craven French. France would give the PLO the status and recognition it seeks without asking the PLO to make even faintly matching concessions in returns. The British formula for anew U.N. resolution is cut from the same cloth.

The European approach cuts directly across the Camp David effort to draw West Bank and Gaza Palestinians into a give-and-take negotiation. It can only help spoil what slight chances remain for Egypt and Israel to pick up the pace of the autonomy talks by the "target date" of May 26. The Europeans, who speak for many in the American bureaucracy, insist that these talks are doomed. They are helping doom them.

In a situation in which everyone has acted badly, the temptation is to take it out on one party. This is what the administration did at the United Nations. Any Arabist worth his salt can justify it and make the case that, in the face of a stalemate, there is geopolitical cause to show sympathy for the PLO, even if no real results flow from it.

I would argue, however, that policy should offer at least some delivery on the Camp David promise to fit the Palestinians into a Middle East peace. The Camp David consensus, always fragile, is bucking. But nothing is at hand to replace it.That should sober serious people. It should make them more, not less eager to squeeze drops of progress out of the autonomy talks. It should interest them in effective ways, not self-defeating ones, to get Israel to reverse its destructive settlements policy. It should quicken the search for ways to draw the Palestinians -- that means the PLO, in one form or another -- into negotiations.

With Israel in negotiations and the Palestinians not, all attention gets put on forcing changes in the Israeli position. Seeing this, Palestinians avoid negotiations, which necessarily bring painful internal conflicts. Begin understands; he may prefer stalemate, even confrontation with the United States, to real negotiations with Palestinians. But the American interest still lies in drawing Palestinians in -- not French style, kissing their hand, but pressing them to make the kind of rending changes that the Israelis must make, too.

This cannot be done by May 26, nor by Nov. 4. Probably it cannot be done by Begin, perhaps not by Carter. But it is the only thing in the Middle East Worth trying to do, and meanwhile there is no point in making things worse.