In yet another triumph of myth over experience the American people have chosen a president whom they expect shortly and not too painfully to repair the United States' tumbled-down position in the world. It was that way with Jimmy Carter in 1976 and it is that way with Ronald Reagan in 1980. The incorrigibly optimistic cast of mind of the American people is again shining through, providing a continuity -- a troubling continuity -- in a transition otherwise seemingly marked by change.

Jimmy Carter, as we know, entered the White House not only accepting but encouraging high foreign policy expectations, notwithstanding the objective difficulties and his thin preparation for dealing with them. He thought that the world was tractable enough, and his own talents ample enough, to sustain his ambition. His personal religiosity, a post-Vietnam mood nourishing a belief in rebirth, the misleading inspiration of his Camp David virtuosity and the enthusiasms of the advisers he came to rely on all propelled him on.

Propelled him on, I might add, to frustration both in terms of his major foreign policy objectives and in terms of the public's appreciation of his policy. Not by accident did his reelection campaign expire in the fading of hopes that the hostages were finally coming home. Carter and the rest of us might have been better off had he come to power regarding the world as a nettlesome, constricted place in which only modest and incremental changes could prudently be essayed, a place in which the national and personal penalties for overreaching were severe. If he had, the American people might have answered quite differently Ronald Reagan's searching question of whether they felt more or less secure after four Carter years.

Now we have a new president who promises to put the American Humpty Dumpty back together again.Like Carter, Reagan has the self-confidence born of his unorthodox and, to most people, unlikely election victory. Like Carter, he has the simplicity of international outlook that arises from a superficial exposure to the problems in the past. Like Carter, he exudes the certainty that America remains a land of the moral frontier, an international one, with a shining global mission that it is his duty to fulfill. Like Carter -- indeed, more than Carter -- he can fairly claim that he has a popular mandate to fulfill that mission in his chosen way.

The basis on which Reagan's promise in policy is commonly distinguished from Carter's record is his "realistic" emphasis on accumulating military power and being prepared to wield it if necessary. But the deeper truth lies elsewhere. Carter's world view, or the one he started out with, rested on the notion of an American-led moral revival offering the country benefits both psychic and real. Woolly, right? Meanwhile, Reagan speaks, with the fervor of American secular religion, of confidence in the future -- as though the future were a spacious and hospitable and almost perfumed realm, especially for Americans, and as though demonstrating confidence in it was the key to getting in. So much for the "hardheaded" Reagan.

I do not happen to be one who thinks our problems in the world will yield appreciably to Reagan's sort of muscularity, but I recognize, somewhat glumly, that the voters have spoken on that question. It is his innocence, the sense he conveys of being immune to the common afflictions of policy, that concerns me here.

In important ways, things are likely to be tougher for Reagan than he makes out.

In general, his blue-sky, no-limits, get-America-moving-again approach to foreign policy risks inducing him to attempt too much too soon, to skip over the need to set priorities (at first, modest ones), to unleash advisers interested mostly (and narrowly) in their pet projects and to allow popular expectations to get out of hand.

As for some sample specifics, his readiness to junk the grain embargo could quickly bring down the whole structure of international sanctions mounted against the Soviet Union on account of Afghanistan, leaving the anti-communist Reagan in the ironic position of cutting the costs of Soviet aggression. His plans for junking SALT II and challenging the Kremlin to an arms race have already begun to traumatize the NATO allies and could worsen what some of his advisers see as Europe's well-advanced "Finlandization."

Finally, there is the politics of foreign policy. The Reagan landslide did more than produce a Republican majority in the Senate. Many in that majority make Reagan look flabby. To the extent that Reagan, under tutoring, moves toward the middle, he will tempt hard-line reprisals that could evoke the executive-congressional collisions of Carter's time. The reappointment to the State Department of Henry Kissinger -- distrusted by some for his early detente role, by others for both -- could provide an early testing.