The death of Tancredo Neves the 75-year-old man who was elected president of Brazil but taken mortally ill before he could be sworn in -- will strike many people here as a kind of freak accident, an antic turn of fate. In Brazil it will be regarded differently -- as a cosmic act of cruelty and injustice. Something akin to exultation marked that country's attitude toward its return to civilian democratic rule this winter, and something akin to reverence had come to mark its feeling for Neves, who had done so much to help accomplish the transformation. Late last month when I was in Brazil, between the second and third of what were to be seven operations on poor Neves, two emotions seemed to prevail. One was dejection that Neves was so sick; the other was determination that the democratic constitutional order should survive, no matter what happened to the ailing president.

You heard this determination expressed everywhere. And you heard comparable commitments to a new effort at democracy throughout the hemisphere. In fact, the parts of South America I visited -- Brazil, Argentina, Uruguay and Peru -- seemed to be experiencing a kind of frenzy of democratic politics, an overwhelming rush of excitement at the return of civilian government after a prolonged spell of military rule and roughly half a century of instability and coups and tugging and hauling among strongmen and charismatic loonies and such normal democrats as from time to time held sway. Both Brazil's misfortune and its coming effort to hold the new democracy together in trying times and under a far less popular leader than Neves can only be understood in this larger context.

In a way the political frenzy put me in mind of Spain and Portugal a decade ago. There too you could see Catholic countries coming out of 50 years of authoritarian rule with an exuberance for democracy and a gift for it that confounded expectation. (The political pin-up boy of the South American countries I visited, by the way, frequently mentioned as an example for newly liberated Latin politicians, is the young, pragmatic Socialist prime minister of Spain, Felipe Gonzalez. His is considered to be a success story in overcoming some of the same obstacles now facing his South American counterparts.) But in some ways I was more powerfully reminded of post-colonial Third World countries than I was of Spain and Portugal. It is as if these places are coming out of colonialism. There is a comparable kind of spirit in the air.

There are also, of course, comparable troubles. Recently in Uruguay, Argentina and Brazil, and a little farther back in Peru, military governments were eased or shoved out not because (as some of them claimed) they had achieved the stability and security for the country that was their only goal in taking power, but rather because they had fouled up. This was especially true in relation to the wrecked economies over which they had presided. So now you have a difficult situation in all these Latin countries that is very similar to one that has afflicted many countries newly freed from colonial control: There is elation that the old order is gone, but the rewards of the new order seem nonexistent. The first call of the democratically elected government must be for cutbacks and sacrifices to achieve economic stability and pay off the errors and aggrandizements of the past. In Zimbabwe or Brazil it is the same in this respect: "Welcome to democratic self-rule. It is going to cost you plenty. There may be no material improvements at all to show for it for years to come. Your government will be busy undoing past damage and demonstrating to other countries that it is responsible. Isn't freedom wonderful?"

The added difficulty is that once the strongman government is gone, labor unions and other economic and social groups feel safer in demanding better wages and fuller benefits, which run directly counter to civilian government's austerity programs. So the people who run those civilian governments require extraordinary personal authority to generate the required painful support for their policies. It was thought that Tancredo Neves had such authority, which is why his death was so especially cruel for Brazilians and why his successor, Jose Sarney, faces such a formidable challenge. But in fact any president of Brazil (or Argentina or Peru or even Uruguay with its longer, though interrupted democratic tradition) would find this a challenge. That is because much of the instability of recent decades in South America, the social and political turmoil of the region, is due to a very thin and chancy sense of the legitimacy of government institutions in the first place.

In Brazil people cling tenaciously these days to the word and letter of the constitution, citing it literally to answer perplexities. It is as if there were no larger, informal understanding of where authority lies and how it works and actually there is none. In Argentina it is being severely questioned whether the present government has the mandate or the strength to do any of the things it considers essential to governing. Taxes are a joke in many of these countries. A huge "informal" sector exists in Peru, which means huge numbers of poor people appropriate land, build unauthorized hovels on it, steal electricity off main lines to light and power it and then just settle in. The independent, roving band is a model of enterprise and settlement in many places on the continent. The history of one system's displacing another over the years in politics has made all of them suspect and weak. The toughest job facing all of these new governments is that of establishing its own legitimacy and thus its claim on the loyalty of its citizens, its claim, at the simplest level, to be listened to.

That, interestingly, is what Tancredo Neves had managed, all but miraculously, to establish in Brazil. And that is why his death is so consequential. It's not that people fear a grab to retrieve power by the military there. It's that they fear no one else has Neves' authority or his presumed legitimacy with the people. This is a problem -- the problem -- for all the newly elected democratic governments of South America.