PERU'S VOTERS were following a clearly visible logic when they chose the previously unknown Alberto Fujimori to be their next president. First of all, his chief opponent, Mario Vargas Llosa, a novelist of world reputation, comes from the urban middle-to-upper class, European in its descent and its outlook, that has always run things in Peru. Over the past two decades the country's leadership has made a spectacular mess of its affairs. Second, Mr. Vargas Llosa sought to break away from that bankrupt tradition in a direction that evidently made most of the voters uneasy. A conservative, he warned them explicitly (and correctly) that their economy can't be stabilized without a period of austerity.

Or, as Peruvians might put it, greater austerity. The country is going through a grinding depression, and real wages have dropped some 60 percent in the past couple of years. When Peru borrows from abroad, as it did in the 1970s, or when it pumps up consumer demand, as it did in the mid-1980s, the benefits flow mostly to the cities and to the middle and upper classes. But when it has imposed austerity, at least in the past, the impact has fallen mostly on the bottom half of the income ladder.

In Mr. Fujimori, the Peruvians now have a president who managed to get through the campaign without offering more than the vaguest hints of his intentions. He takes over a country in severe economic decline, with a soaring inflation and a savagely violent guerrilla movement. Under the outgoing president, Alan Garcia, Peru has had more than enough of fake cures and posturing. Mr. Fujimori now has to try to govern a country in which public trust in government has fallen to zero.

It would be nice to think that aid or international support could somehow turn the course of events for Peru. But until Mr. Fujimori can find ways to give Peruvians a sense of hope, and some reason to think that they are being governed competently, outsiders can contribute little.

Americans have a strong interest in Mr. Fujimori's success, nonetheless. Among many other reasons, Peru's mountain valleys are the source of most of the world's coca and, consequently, cocaine. As the country grows poorer and its peasants see fewer alternatives, the coca trade is going to become harder than ever to suppress. Military intervention, even with American helicopters and advisers, isn't going to suffice. Cutting down coca production will be possible only in a more stable society in which people can see around them better ways of earning a living.