At the risk of tempting fate, I'll say it anyway: something new and promising seems to have been added to the Reagan administration's approach to the Middle East. A certain subtlety, for one thing, but I would add renewed energy, a sense of purpose, a readiness to accentuate the positives -- and, most important, a reordering of priorities.

The Arab-Israeli-Palestinian conflict, it now appears, is back where it belongs on the administration's front burner, never mind the old Israeli arguments for cooling it.

Once again, U.S. policy seems grounded on the sound proposition that Islamic extremism and the Palestinian conflict are intertwined and thus doubly dangerous because.

If that proposition was accepted in the first Reagan term, it hardly showed in the 18 months it took to develop the Sept. 1, l982 definitive Reagan "peace initiative" and the limp effort put behind it thereafter. Recent developments, however, offer interesting evidence of a second-term turnabout.

This week, for example, U.S. and Soviet officials will sit down for two days in Vienna to talk about the Middle East -- including the Arab-Israeli issue. The administration has been at pains to insist that this signifies no change in the administration's refusal to deal the Soviets in on the peace talks, but merely an "exchange of views," with no agreement expected, is better than a rebuff to that part of the new Jordanian-PLO agreement on a "framework for common action" that would specifically bring the Soviets into the act. The "framework" conflicts in other important respects with U.S. positions and will certainly be put down as hardly worth talking about with the Israelis. But the Reagan administration wisely latched on only to the affirmatives.

"It seems as if some progress has been made," Reagan said, adding "We're being optimistic about it." Official background briefers called it "a milestone" and noted that it represented the first Palestinian commitment "to a peaceful settlement." Conspicuous by its absence, officials pointed out, was the standard Arab insistence on an independent Palestinian state with Jerusalem as its capital.

This is an important advance from the so-called Fez Declaration by the Arab League in September 1982, which is the only collective Arab response to Reagan's "initiative." But it was rather more positive, even its rejection of the Reagan plan, than the rejection of the Reagan initiative in its entirety by a unanimous vote of the Israeli Cabinet the day after the plan was announced. When King Hussein of Jordan failed, after an eight-month struggle, to deliver Arafat to the peace table, the whole process collapsed.

That's what makes the recent burst of activity so striking, for it included not only the agreement between Hussein and Yasser Arafat of the PLO but another latching on to the affirmative in a meeting between Reagan and the principal author of the Fez plan, King Fahd of Saudi Arabia. If they squabbled within the White House over the shortcomings they obviously find in each other's handiwork, it didn't show in their joint communique. On the contrary, Reagan sent Fahd home with a pat on the back of "appreciation for the Fez consensus, positive elements of which have been recognized by the United States."

At least one wise and experienced Israeli leader, former foreign minister Abba Eban, was optimistic, even before the most recent developments. Writing in the winter issue of Foreign Policy magazine, he argued that the dominant Labor Party element in Israel's government of national unity is no longer "unconditionally opposed" to the Reagan plan, and is also more sensitive to the importance of going slow with West Bank settlements in the interests of keeping options open for future territorial compromise. His great fear, he said, is of American "passivity (which) would condemn the Middle East to a volcanic status quo leading to possible explosion."

While offering no guarantee of success for an American role, he did offer a little homily that nicely captures what would appear to be an increase in the Reagan administration's involvement, as reflected in its performance in the last few days. "In the Middle East," Eban wrote, "we must learn to be grateful for small mercies -- in which case we should stop calling them small."