Even before the full scope of the Falklands crisis emerges, there is one aspect of it that strikes the eye. It is the good old mixture of prejudice and ignorance of an American government when it has to deal with Latin American affairs.

There is almost invariably a sudden urge in Washington to guess what might be the overall reaction of Latin America to the open, although uncomfortable, alignment of the United States with Britain in the present crisis. There is no such thing as "Latin America" as idealized or feared by Washington, for the very same reason that there is no such thing as "Europe," when it comes to the self-interest of each of its components.

This is particularly true in Brazil, where hardly anyone feels much emotional connection with the Argentine drama. The naval battles in the South Atlantic are followed with passion as a war game turned deadly serious, but not as a battlefield where a close friend is fighting for his life. What there is, for good reason, is a grave concern within the Brazilian government about the political fallout in Argentina after the guns quiet down. Something close to an Argentine victory over Britain might inflate the military arrogance in Buenos Aires to a very undesirable level. Inversely, a military defeat of the Argentinians, it is feared, could result in a leftwing government in Buenos Aires, which appears twice as undesirable to the Brazilian government.

Nobody should doubt that the American siding with its European ally will become duly registered in the history textbooks of our continent and in the memories of present and future Latin American leaders.

On the other hand, no one in Brasilia, Caracas or Mexico City really expected the American government to throw its colossal weight on the side of Argentina. At best, and this is the major complaint being made against the Reagan administration, the United States should have managed to remain officially neutral. Even in Buenos Aires, the voice that was apparently most persuasive in conveying the assurance that the United States would side with Argentina -- Gen. Miguel Mallea Gil, the Argentine military attache in Washington -- is said to be up for a long political exile in his own country.

Most of the Latin American countries have come a long, long way in their beliefs and disappointments, and have sort of majored in American affairs over the years. President Nixon boosted a few egos here in the early 1970s by stating that Latin America would follow the path chosen by Brazil -- a statement that caused quite an uproar among our neighbors but filled with pride the regime of Gen. Emilio Garrastazu Medici, then president of Brazil.

One of the last moments of political fantasy we went through occurred in 1976, when Brazil and the United States signed a memorandum of understanding. It was believed at that time that we had been upgraded to "first- class allies" and that the United States would actually consult the military regime in Brasilia before taking any major decision on foreign affairs. During that period, Brazilian Foreign Minister Antonio Azeredo da Silveira was envied by most of his Latin colleagues for being on "Dear Henry/Dear Antonio" terms with Secretary of State Kissinger.

Fortunately, this diplomatic honeymoon did not last long. By September 1976, when Silveira went to Washington for what he thought would be at least a day-long sesson of wide-ranging talks with Kissinger, the secretary of state accorded him only two meager hours. Silveira threw away the Bahia cigars he had brought for "Henry" and our bilateral relations became more solid -- the inevitable frictions that do occur are handled by the Foreign Ministry in Brasilia without any undue fuss. This week's scheduled visit to Washington by President Joao Figueiredo will show this welcome maturity.

But the same smooth passage from apparent closeness to amicable distance cannot be expected in the case of Argentine-American relations after the Malvinas fiasco. And the Reagan administration is to be blamed for that.

Since he was sworn in 16 months ago, the president of the United States has embraced the controversial theory that totalitarian (i.e., communist) regimes are to be differentiated from authoritarian (i.e., anti-communist) dictatorships. Jeane Kirkpatrick, U.S. ambassador to the United Nations and professed inventor of this intellectual acrobatics, rapidly gained ground among several military dictatorships -- including Argentina's -- which felt that their somber journey through the Carter administration was finally coming to an end.

"Allies are allies, as long as they are anti-communist," become the motto, and they could expect special treatment if their loyalty to the common cause was kept alive. It so happens that the military regime in Argentina was (and is) staunchly anti-communist, sided with the Reagan crusade in Central America and was willing to be part of a new Western alliance based on ideology alone.

The fact that this same regime had no representativeness, let alone popular support, or that it was one of the most repressive regimes in Latin America, did not seem to matter. Nor did the Reagan administration seem to bother about the personal characteristics of the generals who ruled in Buenos Aires. How come, then, that Secretary of State Alexander Haig now is quoted in The New York Times calling them, bluntly, "a bunch of thugs"! Either they were thugs before the Malvinas crisis, or not. But the conflict certainly did not turn them into something they were not before. Exactly the same thing applies to Argentina's genuine claim to the Malvinas.

After these inconsistencies, generations to come in Argentina will harbor a very deep resentment and lack of confidence in whatever comes from Washington.

For many Latin American leaders, the Malvinas crisis will leave an unpleasant taste. The United States had to make a choice between two groups of old friends. Few realists doubted how Washington would behave if forced to choose. But even fewer people believed a crisis would emerge in which the United States would have to pick its preferred group of allies. The opportunity came, and the United States behaved as expected. But the ones passed over will feel they have been treated as second-class allies. How advantageous is it to be a second-class ally?

In its Central American obsession, the Reagan administration has threatened to resort to the Rio Treaty to counter what it considers foreign interference in some countries of that area. In the past, Washington had been able to mobilize most governments of the Southern Hemisphere to support actions against Cuba and in the Dominican Republic on the basis of that treaty. But if this old document is not good enough now to protect a Latin American country against Britain, questionable as the Argentinian action may be, how will the United States be able to use it against Cuba or Nicaragua in the future?

The consequences of the United States siding with Britain are not in yet, but there are already many questions on the sincerity with which Washington uses the Monroe Doctrine. Will Reagan be able to use it after the Malvinas?

After this whole episode disappears, a recurrent problem remains for any country dealing with the United States -- the short-lived nature of American foreign policy, which does not manage to survive even the four years of a presidential term. Unless the incumbent is reelected -- and this has been a rarity in Washington over the last decades -- a whole new grand design of priorities and decades -- a whole new grand design of priorities and strategies will be concocted in the White House.

Although adjustments are certainly necessary to enable the American colossus to face new situations through the world, some basic lines should, perhaps, be kept untouched. This would not be enough to prevent the Falkland crisis, but might have spared Alexander Haig a lot of trouble, time and effort.