The crisis of France's breakfast: morning croissants or socialism?

It is 5:30 a.m. at the bakery on Rue de Babylone in the center of Paris.

Claude Bilnet, the owner, pulls out a rack of golden soft and flaky croissants, ready for the breakfast plate. Despite the early hour and the prospect of 12 more hours on the job, Mr. Bilnet smiles with pride as he looks over the savory rolls.

But turn the subject to France's Socialist President, Francois Mitterrand, and the smile disappears.

''If Mitterrand makes me do that, I won't be able to stay in business,'' he says.

No more fresh croissants? ''No more.''

His reaction is typical of France's many artisans, who are angry at Mr. Mitterrand's program of cutting work hours. In February the government decreed that workers are supposed to toil only 39 hours, down from 40. And if things go as planned, they will labor only 35 hours a week in 1985. The idea is to improve the worker's lot and open up new jobs.

But for bakers and other artisans such as chefs and hair stylists, the 39 -hour workweek provoked a crisis.

In these fields workweeks traditionally last around 50 hours, and to cut working hours so drastically would cause a wave of bankruptcies in these small businesses, the artisans argued. The baking craft, for example, calls for both boss and worker to put in long days, beginning in the wee hours of the morning. Otherwise there would be no fresh bread for breakfast.

And since most of France's 40,000 ''boulangeries'' are family-run operations with three to five employees, they are unable to afford additional workers to compensate for the shorter workweek. A study for the National Bakers' Association claimed that if the 39-hour law was applied to bakers, half of the country's ''boulangeries'' would be forced to close.

As a result, the bakers' workweek became a test of how far Mitterrand was aiming to change France. Could the country do without its morning croissants?

Apparently not. Bosses and workers recently agreed on a 47-hour workweek in bakeries, down from last year's 49-hour maximum. And Mr. Mitterrand appears ready to accept this contract, even though it violates the 39-hour principle.

''There is no other choice,'' a Labor Ministry spokesman said. ''This is the old system of work in France.''

So France's artisans will continue to work long weeks - with union agreement. Up to 500,000 workers are affected, according to the Labor Ministry.

For such artisans working overtime is considered necessary to achieve excellence. Cooking gourmet meals in three-star restaurants or styling hair in the modes of fashions simply takes more than 39 hours a week. But is it just pride that makes these artisans willing to forgo the benefits of socialism?

''No, bakers are willing to work so hard because they know they can rise to become an owner,'' says Francois Guillerme, secretary general of the Paris Bakers' Association. ''Individual enterprise is rewarded.''

The baker Bilnet, for example, started out as an apprentice baker in Lyon 17 years ago. Now he owns his own bakery in the heart of Paris. He works much more than his employees, up to 80 hours a week, beginning early in the morning.

''If I didn't work so much, I would only make the minimum wage,'' he says. ''But I am the boss and that is a terrific feeling.''

He puts the batch of steaming croissants in the counter and opens the bakery for business. For the first hour until his salesgirl arrives, he will tend the register.

An older man enters. ''Deux croissants, s'il vous plait,'' he says.

''Oui monsieur,'' Bilnet responds, handing him two delicious-looking rolls. Both men smile.