Miracle? In Argentina? A country headed straight for economic self-destruction a few weeks ago, where the value of money was going down so fast that by year end it would have been worth less than a tenth of its value at the beginning of 1985? Yes, the Alfonsin shock treatment announced on June 13 may quite possibly prove an authentic modern miracle.

The Argentine president imposed:

* Tight price and wage controls. Both wages and prices had been going up 1,000 percent a year the day before the new plan was announced.

* Deindexation, in a nation where everything was indexed to the inflation rate.

* A new currency pegged to the American dollar. At $1.25, it replaces the old peso that had been worth a tenth of a cent.

* A balanced government budget. The deficit had been exploding, paid for by rolling the printing presses.

When it announced the new program, the government held its breath, and closed the banks. When the banks finally reopened a week later, the lines of waiting customers stretched out for blocks. One high official on his way to the office in the early morning thought that the nation was in a financial panic. He came to realize a few hours later that the public reaction was wildly enthusiastic. Instead of withdrawing their money, people were renewing deposits and taking dollars out of the mattress to buy the new Argentine austral.

Reserves began to build. Watch committees were organized by school districts to monitor prices and bring pressure on retail stores to maintain the freeze. Businessmen joined in the support. Trade union leaders welcomed the possibility that the nation might get off the inflation roller coaster. The shock program had the enthusiastic backing of four out of every five Argentines.

I arrived in Argentina the day banks reopened, intent on running my own private opinion poll. The first stranger I talked to was a down-at-the- heels parking lot attendant. He had seen economic reforms come and go. "I believe in this plan," he said. "For the first time, we have a president who wants to lead and a program that could work. All the people of Argentina feel the same way. Of course, in the end, it depends on God. And God has a lot of things on his mind right now."

I found the same sentiments all across the spectrum of Argentine life -- political figures, businessmen, trade union leaders, bankers. Women were particularly supportive. They concluded that the program might let them regain control of their household economic destinies.

In short, the shock treatment passed its first test with flying colors. But the next will be difficult -- to persuade the people that the government really means to balance the budget. Argentines are financial wizards; they have had to be to survive. And they know that the minute the government begins to print money again, all bets are off and Argentina is on the way once more to world-record inflation.

There is a widespread hope, however, that the Alfonsin administration has done its sums and will be able to finance its reduced expenditures with existing and new revenues. It also looks to be ready to restructure the economy, divesting itself of some of the loss-making public-sector enterprises and offering new and more favorable oil contracts to foreign investors.

Argentina's politics give Alfonsin some running room. His personal popularity has soared since the shock treatment began. The opposition Peronist Party is split. And the mighty General Confederation of Labor, historically Latin America's most militant trade union, now has new leadership committed to democracy and persuaded that democratic institutions and the interest of working people both depend on stopping inflation and starting growth. It is even conceivable that the government, the unions and business can fashion a breakthrough deal in which organized labor would agree to a freeze in wage demands in exchange for the maintenance of employment during a year or two of adjustment.

Paradoxically, Alfonsin's most serious opposition may be in his own party, the Radicals. The technocrats who stitched the new plan together, and who are responsible for its remarkable initial political acceptance, are not party hacks. The established Radical Party leadership, which has grown old playing traditional Argentine politics, distrusts them and their success. Many Argentines are persuaded that Alfonsin must isolate them if he is to succeed in carrying his program through the next difficult stages.

And the program is in for some rough days ahead. Wage controls and price freezes are difficult enough in the best of circumstances. Capital movements can overwhelm fixed exchange rates. So the technocrats know that they will have to manage a delicate transition and maintain a high level of public confidence at the same time. They also know that that happy day is not yet here when inflationary expectations are squeezed out of the system, new foreign investment rolls in, growth takes off, jobs multiply and a rigid and uncompetitive economy shakes itself into world-class efficiency.

Yet, it would be a mistake to bet against this miracle. So far, not many Argentines are. There is a widespread sense of cautious hope. A nation, tested by a humiliating military defeat in 1982 and an anguishing lurch from authoritarianism to democracy in 1983, and which, by putting its own former military leaders on public trial, is now coming to terms with the human rights atrocities of the past decade, is facing up to yet another national challenge.

If the miracle comes to pass, the consequences will be felt far beyond Argentina. The cause of democracy in the hemisphere will have received a real lift. And Alfonsin will have proved that fighting inflation and turning an economy inside out, even in the midst of an international debt crisis, is good politics in Latin America -- if a nation comes to believe that the hardship is fairly shared and that there is hope around the corner.