Two years after the election victory of Socialist President Francois Mitterrand, many Frenchmen feel as if they are in the grip of what one writer has called "a light hangover."

It all began with a wonderful party. Singing and dancing, tens of thousands of jubilant Socialist supporters poured into the streets of Paris on the night of May 10, 1981, to celebrate the end of more than two decades of conservative rule. Right-wingers watched aghast as the new Socialist ministers launched a sweeping program of reforms that included nationalization of the major banks and industrial groups and an all-out push for economic growth.

Two years later, France's socialist experiment has gone sour. The ambitious economic goals with which the left came into office have had to be abandoned in the face of international constraints. Mitterrand's standing in the opinion polls has slumped and the first signs have emerged of social unrest in the form of strikes and street demonstrations.

The government can claim credit for significant social reforms such as the reduction in the work week, abolition of the death penalty and a project to decentralize political decision-making away from Paris. In foreign policy, it has won points from the Reagan administration for its forthright warnings against Soviet attempts to decouple Europe from the United States. But in the all-important area of domestic economic policy, its record has been marked by confusion and humiliating U-turns.

Soon after their election victory, the Socialists set about trying to reflate the French economy, despite the fact that the rest of the world was still in recession. A year later, the strategy had to be reversed following a dramatic rise in the foreign trade deficit.

Today, just as other western countries are talking about reflation, France seems condemned to several more years of harsh austerity measures and no economic growth.

The economic and political consequences of that initial policy decision are likely to shape the remaining five years of Mitterrand's term. In the words of a former Socialist minister, France is now obliged to "pay the price" for the haste with which the government sought to carry out the program on which it was elected.

The experience of the last two years seems to have confirmed a self-perpetuating political mechanism that has kept the French left out of power for the greater part of this century despite the fact that it enjoys the support of almost half the electorate.

A typical cycle begins with the election of a left-wing government at a time of economic crisis as part of a general reaction against the right. The new government's attempts to "keep faith" with its electors by massive public spending only make the crisis worse. The leftists acquire a reputation for economic mismanagement, are forced out of office, and spend their time in opposition dreaming up schemes for changing society until the cycle turns yet again.

Previous interludes of left-wing rule in France have averaged about two years each. The period 1956 to 1958 saw a series of center-left administrations before Charles de Gaulle was swept back to power following a military uprising in Algeria. Leon Blum's popular front government made up of Socialists and radicals and supported by the Communists, was in power from 1936 to 1938, when it was brought down by a wave of strikes.

It is one of the great ironies of French politics that Mitterrand's ability to remain in power beyond the time traditionally allotted to left-wing leaders rests on the strength of the institutions of the Fifth Republic. The present French president was once one of the foremost critics of the 1958 constitution, which was written at de Gaulle's behest in order to strengthen the authority of the executive at the expense of parliament. He expressed his feelings in a book entitled "The Permanent Coup d'Etat." French Socialist Reforms Turn Sour After Two Years By Michael Dobbs Washington Post Foreign Service

PARIS, May 10--Two years after the election victory of Socialist President Francois Mitterrand, many Frenchmen feel as if they are in the grip of what one writer has called "a light hangover."

It all began with a wonderful party. Singing and dancing, tens of thousands of jubilant Socialist supporters poured into the streets of Paris on the night of May 10, 1981, to celebrate the end of more than two decades of conservative rule. Right-wingers watched aghast as the new Socialist ministers launched a sweeping program of reforms that included nationalization of the major banks and industrial groups and an all-out push for economic growth.

Two years later, France's socialist experiment has gone sour. The ambitious economic goals with which the left came into office have had to be abandoned in the face of international constraints. Mitterrand's standing in the opinion polls has slumped and the first signs have emerged of social unrest in the form of strikes and street demonstrations.

The government can claim credit for significant social reforms such as the reduction in the work week, abolition of the death penalty and a project to decentralize political decision-making away from Paris. In foreign policy, it has won points from the Reagan administration for its forthright warnings against Soviet attempts to decouple Europe from the United States. But in the all-important area of domestic economic policy, its record has been marked by confusion and humiliating U-turns.

Soon after their election victory, the Socialists set about trying to reflate the French economy, despite the fact that the rest of the world was still in recession. A year later, the strategy had to be reversed following a dramatic rise in the foreign trade deficit.

Today, just as other western countries are talking about reflation, France seems condemned to several more years of harsh austerity measures and no economic growth.

The economic and political consequences of that initial policy decision are likely to shape the remaining five years of Mitterrand's term. In the words of a former Socialist minister, France is now obliged to "pay the price" for the haste with which the government sought to carry out the program on which it was elected.

The experience of the last two years seems to have confirmed a self-perpetuating political mechanism that has kept the French left out of power for the greater part of this century despite the fact that it enjoys the support of almost half the electorate.

A typical cycle begins with the election of a left-wing government at a time of economic crisis as part of a general reaction against the right. The new government's attempts to "keep faith" with its electors by massive public spending only make the crisis worse. The leftists acquire a reputation for economic mismanagement, are forced out of office, and spend their time in opposition dreaming up schemes for changing society until the cycle turns yet again.

Previous interludes of left-wing rule in France have averaged about two years each. The period 1956 to 1958 saw a series of center-left administrations before Charles de Gaulle was swept back to power following a military uprising in Algeria. Leon Blum's popular front government made up of Socialists and radicals and supported by the Communists, was in power from 1936 to 1938, when it was brought down by a wave of strikes.

It is one of the great ironies of French politics that Mitterrand's ability to remain in power beyond the time traditionally allotted to left-wing leaders rests on the strength of the institutions of the Fifth Republic. The present French president was once one of the foremost critics of the 1958 constitution, which was written at de Gaulle's behest in order to strengthen the authority of the executive at the expense of parliament. He expressed his feelings in a book entitled "The Permanent Coup d'Etat." The powers entrusted to the president under the Fifth Republic make Mitterrand, on paper at least, one of the most powerful democratically elected heads of states in the world. Until his seven-year term ends in 1988, there is nothing the right can do to get rid of him.

The phrase "A Light Hangover" was used by a French political journalist, Olivier Todd, as the title of a book to explain how he felt after two years of socialism. Todd voted for Mitterrand in May 1981 and still feels sympathetic toward the left. But he says his reason tells him that something has gone wrong.

Like many Frenchmen, Todd did not really believe that the Socialists would actually seek to carry out the radical platform on which they ran for office. He imagined that, once in power, Mitterrand would rein in the ideologues on the left of his party and pursue pragmatic, middle-of-the-road policies. The Socialists surprised everybody by doing exactly what they said they were going to do.

Disillusionment came quickly. Unable to stem a run on the franc, the government was forced to devalue the currency in October 1981, less than five months after assuming office. A second devaluation came in June 1982 and a third last March. The franc has lost almost half of its value against the U.S. dollar since Mitterrand's election victory.

Exactly why the Socialists decided to ignore the advice of all the experts and push ahead with their ill-fated plans to expand the economy is still a mystery. Some political commentators have put it down to inexperience after 23 years in opposition. Senior Socialist officials, however, continue to insist that the strategy was carefully thought out.

According to their argument, the social reforms carried out during the early months of the Mitterrand presidency served to legitimize the new administration in the eyes of its natural supporters. This created a fund of good will on the left on which the government hopes it will be able to draw during the difficult period that lies ahead. Mitterrand felt obliged to show that he was charting a different course from that of his discredited predecessor, Valery Giscard d'Estaing.

None of these explanations is fully satisfying. Michel Crozier, one of France's leading political sociologists, contends that the root of the problem lies in the fact that the French Socialist Party has never been able to rid itself of its "utopian visions" for changing society.

"It used to be said that the French right was the most stupid right in the world. It's equally possible to say that our left is the most stupid left," he said.

He added: "Elsewhere in Europe, the socialists have become social democrats. They have been successful in bringing reformist change to West Germany and there is now a healthy alternation of power between a moderate right and a moderate left. Both the Spanish and Portuguese socialist parties have made great efforts to dissociate themselves from the policies pursued here. It is only in France that the Socialist Party retains a belief in Utopia."

There are still many people within the French Socialist Party who think the government is making a mistake not to press ahead with its original plans. In a recent open letter to Mitterrand, the party's number two man, Jean Poperen, wrote that the socialist experiment would "fail if the government sacrifices its political obligations to the constraints of the economy." Finance Minister Jacques Delors has depicted himself as a lonely fighter for economic good sense and lashed out at left-wing "bazaar economists" who criticize his austerity program.

In June 1981, a month after the Socialist election victory, 74 percent of Frenchmen expressed confidence in Mittterrand's ability to solve France's problems, according to an opinion poll published in Le Figaro magazine. Today, according to the same poll, only 49 percent of the electorate still have confidence in Mitterrand. Another poll shows that 59 percent of Frenchmen think France is "badly The powers entrusted to the president under the Fifth Republic make Mitterrand, on paper at least, one of the most powerful democratically elected heads of states in the world. Until his seven-year term ends in 1988, there is nothing the right can do to get rid of him.

The phrase "A Light Hangover" was used by a French political journalist, Olivier Todd, as the title of a book to explain how he felt after two years of socialism. Todd voted for Mitterrand in May 1981 and still feels sympathetic toward the left. But he says his reason tells him that something has gone wrong.

Like many Frenchmen, Todd did not really believe that the Socialists would actually seek to carry out the radical platform on which they ran for office. He imagined that, once in power, Mitterrand would rein in the ideologues on the left of his party and pursue pragmatic, middle-of-the-road policies. The Socialists surprised everybody by doing exactly what they said they were going to do.

Disillusionment came quickly. Unable to stem a run on the franc, the government was forced to devalue the currency in October 1981, less than five months after assuming office. A second devaluation came in June 1982 and a third last March. The franc has lost almost half of its value against the U.S. dollar since Mitterrand's election victory.

Exactly why the Socialists decided to ignore the advice of all the experts and push ahead with their ill-fated plans to expand the economy is still a mystery. Some political commentators have put it down to inexperience after 23 years in opposition. Senior Socialist officials, however, continue to insist that the strategy was carefully thought out.

According to their argument, the social reforms carried out during the early months of the Mitterrand presidency served to legitimize the new administration in the eyes of its natural supporters. This created a fund of good will on the left on which the government hopes it will be able to draw during the difficult period that lies ahead. Mitterrand felt obliged to show that he was charting a different course from that of his discredited predecessor, Valery Giscard d'Estaing.

None of these explanations is fully satisfying. Michel Crozier, one of France's leading political sociologists, contends that the root of the problem lies in the fact that the French Socialist Party has never been able to rid itself of its "utopian visions" for changing society.

"It used to be said that the French right was the most stupid right in the world. It's equally possible to say that our left is the most stupid left," he said.

He added: "Elsewhere in Europe, the socialists have become social democrats. They have been successful in bringing reformist change to West Germany and there is now a healthy alternation of power between a moderate right and a moderate left. Both the Spanish and Portuguese socialist parties have made great efforts to dissociate themselves from the policies pursued here. It is only in France that the Socialist Party retains a belief in Utopia."

There are still many people within the French Socialist Party who think the government is making a mistake not to press ahead with its original plans. In a recent open letter to Mitterrand, the party's number two man, Jean Poperen, wrote that the socialist experiment would "fail if the government sacrifices its political obligations to the constraints of the economy." Finance Minister Jacques Delors has depicted himself as a lonely fighter for economic good sense and lashed out at left-wing "bazaar economists" who criticize his austerity program.

In June 1981, a month after the Socialist election victory, 74 percent of Frenchmen expressed confidence in Mittterrand's ability to solve France's problems, according to an opinion poll published in Le Figaro magazine. Today, according to the same poll, only 49 percent of the electorate still have confidence in Mitterrand. Another poll shows that 59 percent of Frenchmen think France is "badly governed" against 32 percent who are "satisfied."

The major question for the Socialists now is whether they can stem this slide in popular support or whether the decline is irreversible. The next few months will be crucial as they are likely to witness the first significant drop in the purchasing power of ordinary Frenchmen since World War II.

Up until now, the economic policies pursued by the government have not adversely affected general living standards. In the opinion of Raymond Aron, a right-wing philosopher and political commentator, "They have hurt France rather than the French." Workers are probably better off now after gaining five weeks of paid vacation, increased social security benefits and a 39-hour work week.

This is all about to change. Next month the French will start paying a forced loan equivalent to 10 percent of their taxable income to the government. Prices are rising faster than incomes.

The major political card still in the government's hand is that it still enjoys the grudging support of the big trade unions, particularly the General Confederation of Labor, which is controlled by the Communist Party. Union leaders have grumbled about the latest austerity package, introduced in March, but seem to have no interest in stirring up industrial unrest. Pressure from the rank-and-file could, however, cause a shift in this attitude.

Edmond Maire, who heads the second largest trade union, the French Democratic Federation of Labor, insists that the "game is not yet lost" for the Socialists. But he accuses the government of failing to consult the unions on the important issues and failing to develop a realistic economic strategy.

"We must reject the notion that there are any miracle solutions," he said.

Many analysts contend that the left's present problems are closely bound up with Mitterrand's enigmatic personality. He is widely acknowledged to be one of the most skillful politicians in France, with a highly developed sense for political survival. Under his leadership, the Socialists have become the most important political party in the country, completely overshadowing the Communists.

What Mitterrand seems to lack, however, is a coherent economic vision for tackling France's problems. As president, his main field of interest has been foreign policy. He is widely perceived as weak and vacillating when hard economic decisions have to be made.

Mitterrand received his training as a minister under the Fourth Republic in the early 1950s and his critics have suggested that his talents are ideally suited to the endless government reshuffles that took place then. The implication is that, while he relies on the institutions of the Fifth Republic to remain in power, he does not know how to use the powers that have been entrusted to him.

France's Fifth Republic institutions, which have proven so strong up until now, could face a crisis if the left does badly in the elections for a new National Assembly in 1986. French presidents since de Gaulle have always enjoyed full control over the legislature.

In order to avoid such a conflict, Mitterrand is now toying with plans for proportional representation. This would water down the expected swing to the right and allow him to govern from the center during the remaining two years of his presidency. Once again, in the view of observers, his political instincts seem to be serving him well.

The bigger question, though, is what will happen to France. Crozier echoes the opinion of many independent observers that the country is going to get ever more difficult to govern as the economy deteriorates.

"The government's survival is not in question, but the country's future is," he says.

This century, left-wing governments have never ruled France for more than two years at a time. France is entering uncharted territory. graphics/1 photo: FRANCOIS MITTERAND ...standing in polls slumps graphics/2 caricature: Mitterand By Steve Mendelson--TWP governed" against 32 percent who are "satisfied."

The major question for the Socialists now is whether they can stem this slide in popular support or whether the decline is irreversible. The next few months will be crucial as they are likely to witness the first significant drop in the purchasing power of ordinary Frenchmen since World War II.

Up until now, the economic policies pursued by the government have not adversely affected general living standards. In the opinion of Raymond Aron, a right-wing philosopher and political commentator, "They have hurt France rather than the French." Workers are probably better off now after gaining five weeks of paid vacation, increased social security benefits and a 39-hour work week.

This is all about to change. Next month the French will start paying a forced loan equivalent to 10 percent of their taxable income to the government. Prices are rising faster than incomes.

The major political card still in the government's hand is that it still enjoys the grudging support of the big trade unions, particularly the General Confederation of Labor, which is controlled by the Communist Party. Union leaders have grumbled about the latest austerity package, introduced in March, but seem to have no interest in stirring up industrial unrest. Pressure from the rank-and-file could, however, cause a shift in this attitude.

Edmond Maire, who heads the second largest trade union, the French Democratic Federation of Labor, insists that the "game is not yet lost" for the Socialists. But he accuses the government of failing to consult the unions on the important issues and failing to develop a realistic economic strategy.

"We must reject the notion that there are any miracle solutions," he said.

Many analysts contend that the left's present problems are closely bound up with Mitterrand's enigmatic personality. He is widely acknowledged to be one of the most skillful politicians in France, with a highly developed sense for political survival. Under his leadership, the Socialists have become the most important political party in the country, completely overshadowing the Communists.

What Mitterrand seems to lack, however, is a coherent economic vision for tackling France's problems. As president, his main field of interest has been foreign policy. He is widely perceived as weak and vacillating when hard economic decisions have to be made.

Mitterrand received his training as a minister under the Fourth Republic in the early 1950s and his critics have suggested that his talents are ideally suited to the endless government reshuffles that took place then. The implication is that, while he relies on the institutions of the Fifth Republic to remain in power, he does not know how to use the powers that have been entrusted to him.

France's Fifth Republic institutions, which have proven so strong up until now, could face a crisis if the left does badly in the elections for a new National Assembly in 1986. French presidents since de Gaulle have always enjoyed full control over the legislature.

In order to avoid such a conflict, Mitterrand is now toying with plans for proportional representation. This would water down the expected swing to the right and allow him to govern from the center during the remaining two years of his presidency. Once again, in the view of observers, his political instincts seem to be serving him well.

The bigger question, though, is what will happen to France. Crozier echoes the opinion of many independent observers that the country is going to get ever more difficult to govern as the economy deteriorates.

"The government's survival is not in question, but the country's future is," he says.

This century, left-wing governments have never ruled France for more than two years at a time. France is entering uncharted territory.