THERE IS a human instinct to freeze big events into cliches that stick in the mind. Andrew Young's dramatic departure from the Carter Cabinet will produce its share; the crowning blow upon a sinking presidency, the end of the black-Jewish alliance in domestic politics, an inevitable victory of the establishment over an outsider, the conclusion of Washington's second honeymoon with the Third World.

But these cliches distort and trivialize the Andrew Young experience, which is symptomatic of a far broader crisis of American foreign policy. Young epitomized many aspects of that crisis -- the runaway ethnic diplomat, the emergence of the "mellow" foreign policymaker, the Rafshooning of the Third World by telling it what it wants to hear.

Ethnic politics, to begin with, is a basic strength of American foreign policy, both healthy and inevitable. But, as in so many other areas, Jimmy Carter converted this American tradition into a national disaster by creating the ultimate in the unrestrained ethnic diplomat, by appointing a man he could not afford to discipline or fire because of the importance of the domestic constituency Young so self-consciously represented.

The principal purposes of U.S. foreign policy, of course, are to protect us from threats to our own and our allies' security and living standards and to advance the possibilities for stable world order. Ethnic foreign policy often starts from other premises and is reluctant to deal with world relationships as they exist. Instead, its key assumption is the primacy of the ethnic cause at home and its reflection abroad. American policy becomes a platform for working out domestic frustrations. Foreign peoples or states -- Greece, Israel, Tanzania -- are championed without reference to their conduct or to the effects of our partisanship on broader U.S. interests.

When a domestic campaign against the evils of "the system" is carried over into foreign policy, the result can be a failure to accept the legitimacy of the United States or to advocate its core national interests. This explains the grotesque equivalence ascribed by Young to Khomeini's executions and the death penalty in a Florida criminal case, or to modern-day Gulag justice in the U.S.S.R. and our own penal system. Which side is our man on? Does he have any concept of the barbarity which passes for politics in much of the world beyond our shores?

Runaway ethnic foreign policy is especially ambivalent about whether our system, and that of our democratic allies, is a benevolent or oppressive influence in the world. It appreciates western technological supremacy, but it questions the domestic and global political order with which it is inextricably intertwined. Our system's traditional adversaries suddenly get the soft sell (Americans are "paranoid about a few communists in Africa"), while our traditional allies get the shaft (Britain has had worse racism "than anyone else in the history of the earth").

Another problem with the undisciplined ethnic diplomat is his confusion about his job. Angered at the resignation, a number of black leaders have pointed out that Young will be missed throughout the Third World, where he was seen as a champion of the underdog black and brown nations. Young himself confirmed this impression in a resignation remark at the State Department: "Unfortunately, but by birth, I come from the ranks of those who had known and identified with some level of oppression in the world. By choice I continued to identify with what would be called in biblical terms the least of these my brethren." This, however, is not the prime function of an American diplomat appointed to represent our immensely complex society -- with its kaleidoscope of ethnic, racial, religious and other groups of all economic backgrounds, not just the poor among blacks -- before the world.

Tactical confusion was also evident. On several occasions in dealing with South Africa, the most emotive issue in the Third World for blacks, Young encouraged the campaign for U.S. corporate disinvestment while adding that he personally did not want U.S. business to pull out. The campaign, he believes, will heighten corporate (and public) awareness while warning white South Africans of the need for rapid change. But what if the campaign ever gets close to its stated objective? Where will Young be when faced with the hard choice?

It is not Young who deserves the principal rap for all of this. He played the hand dealt him by Jimmy Carter and tolerated by the American political system for 2 1/2 years. A "mellow" foreign policy

The Young experience also typifies an era in which America is conducting a "laid-back" foreign policy. Policy elites traumatized by past excesses of U.S. zeal to contain communism now wonder whether Moscow doesn't have a "right" to expand its influence and project its power. All threats can be redefined with such logic. Conflict and threat are seen to flow from misperception or failure in communication. Are the Israelis and the PLO at loggerheads because they do not "understand" each other? With the best of intentions, can one energetic and able communicator resolve a primordial clash of interests and values?

It seems unlikely, especially when the nation for which he speaks is visibly declining in influence and credibility around the globe because of a failure even to address its domestic woes. Yet the mellow policy-maker persists.

The world out there is accepted by mellow diplomats to be an almost infinitely malleable place waiting for the expression of American desires and the exercise of American talents. Endemic conditions of insecurity, strife and scarcity are dismissed or verbally transcended as each new administrration inherits what it mistakes for a blank canvas.

The abiding limits on U.S. freedom of action and influence are dimly understood, while new constraints on us are hardly considered as we launch bold new initatives to save the globe from the ills we perceive in it. By focusing on nonproliferation, social justice, peace, reduced arms races and exports or development, our mellow policymakers ignore the fact that these goals are by-products of more elusive -- and less glamorous -- things like stability, productivity and security.

These, in turn, are produced, if at all, by the conscious choice of governments, including our own. They cannot be manufactured by unilateral American acts of will, charity, preaching or "communication." Andrew Young did not invent these contemporary manifestations of American parochialism, and he is not responsible for them. We are, and we have witnessed in his outspoken career the effects of our self-indulgence. Rafshooning the world

Young and the Carter administration are widely credited with having reestablished U.S. credibility and influence in the Third World, and especially Africa. There are no scientific insturments for testing the claim or for knowing how long influence must last to be considered an achievement. But the claim is, at the least, premature.

Young has played the major role in reducing Eurocentric arrogance, neglect and racist stereotypes from American policy toward these regions. He symbolizes a humane empathy lacking since Kennedy for peoples who experienced European colonial rule. His personal efforts broke down cultural and attitudinal barriers which too often made even personal contact among officials difficult. These are important accomplishments while they last.

But before we rush to conclude that it was worth it after all, let us remember that Washington cannot Rafshoon the Third World any more than Carter can Rafshoon the United States. Consider the parallels. There is, first, the emphasis on flattering or massaging the audience. It is not the listeners who are responsible for their own woes (poverty, inflation or whatever) but the "system," the power structure, the existing order. Internationally, the United States is a substantial element of that existing order; hence it is incumbent on Washington to apologize to the Third World for its past behavior.

Second, there is the syndrome of identifying whatever the audience (Third World governments or voters at home) wants to hear and espousing it as policy. This bizarre but very American way of conducting politics and foreign policy has its consequences. The leader ends up standing for whatever the audience says it wants, and he submerges his own agenda -- if, indeed, he has one.

Diplomacy becomes a popularity contest in which success is measured by having the best possible relations, especially public relations, with the maximum number of governments. In the end, the goals and ideologies we identify with are those of the people who scream the loudest, and all screamers are given equal time.

This accounts for the inevitable rise in the legitimacy of militant nationalists, xenophobes and Marxists during the Carter era. Khomeini becomes "some kind of a saint," the PLO becomes progressively part of the peace process because it demands to be and threatens to bring the house down if its exclusion continues. In the case of Rhodesia, we have witnessed the spectacle of African frontline states showing more pragmatism about a settlement than Young and the State Department, which are allowing a virtual veto by Patriotic Front guerrilla leaders.

The final step in the Rafshooning of the Third World is the use of extravagant promises as an instrument of diplomacy. Of course, when it comes time to deliver and the cupboard is bare, there will always be an ample stock of scapegoats in foreign as in domestic policy -- big oil, our allies' "vested interests," the Congress, conservatives at home and so forth.

This approach to Third World issues has its attractions for those who use it. The crusty habits and shibboleths of the past can be swept away in a frontal assault. But the "gains" provide limited influence for this week and new demands on us the next. Third World leaders want to know what we can do, as well as what we can say.

Andrew Young's tenure as U.N. ambassador, in short, is a contemporary American social epic acted out before our eyes. We are reluctant to recognize so much of ourselves in the career of this humane, blundering, optimistic, confused, arrogant and charmingly direct man. The only surprising thing is how long he lasted in the job. Preoccupied with his "gaffes," we could overlook how profoundly he and many others misconceive the conduct of foreign policy. The danger is that our opinion of him will distract us from much needed thinkging about ourselves.