The United States has reasserts its role as peacemaker of the world economy, and the leaders of the other major industrial countries, despite some misgivings, have crossed their fingers and gone along with Ronald Reagan. That's mainly what has been happening at the economic summit meeting here.

Previous summit sessions throw into stark relief the nature of the present meeting. The first economic summit, at Rambouilet in 1975, was a price exacted by the French for acceptance of an American idea for reform of the international monetary system. At the next session in Puerto Rico, Gerald Ford was certified by his peers, just before the electoral campaign, as a true leader in foreign policy.

Jimmy Carter, an honest-to-God believer in partnership and interdependence, solicited favors at four successive summits. In London in 1977 and in Bonn the following year, he sought Japanese and German cooperation for government policies that expanded economic activity. At Tokyo in 1979 he asked for help against a run-up of oil prices by competitive bidding on the spot market. At Venice in 1980 he tried to keep the others in line with the embargo placed on Russia after the invasion of Afghanistan. A little assistance was forthcoming, but it was grudging, and there was not a wet eye in any of the summit capitals when Carter was voted out last November.

The Reagan administration has concentrated on the American economy with hardly a glance over the shoulder at other industrialized countries. It has tightened monetary poliy considerably, and tried to cut back on social expenditures while pushing for private economic growth through tax relief. Inflation has eased -- in part because of good luck on oil and food prices, but interest rates have hit record highs.

The impact on other advanced countries has been distinctly adverse. In order to prevent a catastrophic flow of funds from their own currencies to the dollar, West German, Italy, France, the Netherlands and Belgium have all had to maintain their interest rates at high levels. As a result, those countries have experienced an extraordinarily slow recovery from the recession induced by the oil prce rise of 1979-1980.

Thus economic growth in the United States will exceed 2 percent this year, and the jobless rate will grow by less than 10 percent. But the four major European countries (Germany, France, Britain and Italy) are suffering a drop in growth and a rise in unemployment of more than 25 percent.

Inevitably, there has been squawking, particularly from the newly elected French government of Francois Mitterrand, who has ambitious social schemes in mind. But Reagan was able to turn aside all the complaints by holding out the hope that rates would go down later in the year. Even Mitterrand, who made a strong pitch on the issue in his private talk with Reagan Sunday night, gave the United States until the end of the year to get the rates down.

The relatively docile acceptance of the American lead by the other advanced countries finds many special political explanations. Margaret Thatcher of Britain agrees, in principle, with the Reagan policies. Helmut Schmidt of West Germany is torn between his own Socialist Party, which favors lower rates and a more expensive economy, and his partners in the governing coalition, the Free Democrats, who, along with the German Central Bank, support the American position.

Pierre Elliott Trudeau of Canada does not want a fight over interest rates to foul his hopes for a bigger commitment from the industrialized countries of the North to the developing nations of the South. The Italian prime minister, Giovanni Spadolini, represents a splinter party so narrowly based he cannot afford to make any waves. Zenko Suzuki wants only to get through the meeting without new threats of barriers against Japanese exports to Europe and North America. At one point, when Trudeau and Reagan were gossiping about how many leaders spoke French and how many English, there spread over the face of Suzuki, who speaks neither, a beatific smile.

A larger consideration, however, takes precedence over all the special, political reasons. When the United States is on the defensive, when Washington does not know its own mind, and looks outside for cues, and chops and changes policies, then all other countries have to back and fill. When the United States makes its own policies with its eyes fixed on American conditions, other countries can adjust accordingly. Then, if things turn sour, or somebody gets hurt, changes can be effected and compensations quickly made. In other words, the world is healthier economically when the United States acts as No. 1.