SYRIA'S PRESIDENT Assad is the latest Middle East leader Mr. Carter has seen in his deepening quest for a regional settlement. As in the earlier sessions, the vibrations were pleasant enough: Each foreign leader who sees the President hopes to impress him with his earnestness and sincerity, and it suits Mr. Carter in this introductory period to smile back. If there has developed any change of position or attitude sufficient to put adversaries within diplomatic hailing distance, however, it is a well-kept secret. Israel insists it won't yield the measure of territory, and the Arabs the measure of neighborly peace, that the other party demands. Israelis and Palestinians still seem remote from mutual recognition. President Carter has one more Arab (Saudi Arabian Prince Fahd) and one more Israeli (the winner of next Sunday's elections) on his guest list. Then what does he do?

The conventional answer is: Geneva. The idea of convening a general Mideast peace conference, in which a place for the Palestinians would be found, has gotten a certain grip on the popular if not the diplomatic imagination. But there is no magic in Geneva or in any other single diplomatic format. On the contrary, there is a serious danger - fortunately, one recognized by most of the Mideast parties - in calling for a conference whose outcome has not been carefully worked out in advance. This holds whether the goal is a comprehensive settlement, or the designation of working parties on sub-issues, or the negotiation of further disengagement agreements involving Israel and Syria or Egypt, or new approaches on the West Bank, or whatever.

In fact, the format and even the timetable are less important than the attitude taken by Washington. Clearly, the Arabs, wielding the oil weapon and the threat of war, want the United States to deliver their lost territory and a Palestinian state without asking them to make compensating political concessions to Israel. But this would make a mockery of American friendship for Israel and possibly set the stage for the next war. Mr. Carter has wisely refused to go down this path. The Israelis have no comparable leverage on the United States. They are, furthermore, uniquely dependent on Washington and, therefore, uniquely vulnerable to American pressure. But, again to hsi credit, Mr. Carter has rejected Israel's demands for support for its territorial objectives and, that lacking, in effect for a long American-subsidized pause in the bargaining. The American interest in good relations with the Arab world, and in Mideast peace, rules out such a course.

We don't pretend to know how to put the pieces together. Judgment on tactics must rest in the hands of those American officials who have been talking in confidence with the Israeli and Arab leaders. We belive, however, that the basic Carter stance - to offer each parties satisfaction of its legitimate aims, on condition that each grants similar satisfaction to its adversary - is the only sound basis on which a settlement can be sought. We are not so much dismayed that Mr. Carter has yet to crack the Mideast nut as we are persuaded that he is going about it in the right way.