FINALLY President Reagan has a Mideast policy worthy of the name. He unveiled it in a lucid, thoughtful and courageous speech, one deserving to be called historic, on Wednesday night. His "fresh start" supplied what had been missing from the earlier Reagan effort to build security links and manage crises in the region: a pledge and a plan to tackle the Palestinian question directly within the context of a concern first of all for Israeli security. Mr. Reagan drew exactly the correct conclusion from the Lebanon crisis and from the earlier virtual collapse of the autonomy negotiations: the United States cannot afford to let the Palestinian question fester more.

The first major point in the new policy is to make a bold bid to draw legitimate Palestinian representatives into the stalled autonomy talks by suggesting that Israel freeze its settlements on the West Bank. Without such representatives, the talks are meaningless -- no, farcical and shameful. But legitimate representatives have boycotted the talks largely because Israel's settlements, among other acts, have convinced them that Israel means to annex the territory, notwithstanding its unequivocal Camp David promise to put the final status of the territory up for negotiation. Most Palestinians have felt, furthermore, that the United States was permitting Israel to pursue an expansionist course.

The Israeli Cabinet, in announcing yesterday that it would boycott any negotiations organized on the basis of the new American positions, insisted that it had the letter of Camp David on its side. The reasonable response was given on the op-ed page, also yesterday, by Jimmy Carter, who was there. "The massive settlement program in the occupied territories, launched by the Israelis contrary to repeated assurances by their leaders," he said, "has been an extremely unpleasant surprise to all of us who had such high hopes for a peaceful resolution of the major Middle East issues."

Mr. Carter also reminded everyone, as Mr. Reagan did in his speech, that United Nations Resolution 242, mandating withdrawal from occupied territory in exchange for peace, applies to the West Bank. Menachem Begin, with annexation in his eye (and in his party's platform), has explicitly rejected that position for years. In the language of the Camp David Accords, however, he at least implicitly accepted it. Therein lies a cruel personal and political dilemma for Mr. Begin. The administration ought to be, and evidently intends to be, sympathetic to his problem, even while it insists on the twice-agreed (in 242 and at Camp David) international language.

There is a second major point of the Reagan proposals. The president still maintains that the final status of the territories must be settled in direct negotiations. However, he guarantees Israel against its nightmare (a Palestinian state) and the Arabs against theirs (Israeli annexation), thereby precluding at least two theoretical outcomes of such talks.

Whether his no-Palestinian-state guarantee to Israel and his call for Palestinians to pursue self-government "in association with Jordan" turn out to be salable to Arabs is a real question. In any event, his no-annexation guarantee to the Arabs was protested yesterday by the Israeli Cabinet on the grounds that Camp David did not preclude application of Israeli sovereignty over "Judea, Samaria and the Gaza District." But it would be absurd to take this first Israeli response as the last. Surely it is the Israeli people's perception of their self-interest, not its lawyers' selective reading of a text, that will ultimately tell.

It is possible to get too much into the detail, on which there will be intense and necessary argument. The new policy serves broad and urgent American interests. It is also, explicitly, an extension of Jimmy Carter's distinctive and elevated reach for the noble objective of a full Arab-Israeli peace. Mr. Carter bet, and Mr. Reagan now bets, that the longing for peace and for secure acceptance is so profound in Israel that it will rise over all evident obstacles. We believe the president is right, and we salute him for accepting the great political risks of putting his perception to a test.