Scientists, businessmen and farmers unhesitatingly, and with general approval, sever ties with the Russians when Jimmy Carter throws a fit about Afghanistan. But Olympic athletes protest cancellation of the Moscow games, and are widely applauded. How come?

The answer, I believe, is that sports occupies a privileged enclave in American life. Along with show biz and the arts, sports is one of very few modern activities that keeps faith with the great myth of American society.

The myth, of course, is that American society is free and easy. Careers are supposed to be open to talent, and opportunities available for those prepared to take chances. The individual is said to count, and the Constitution is cited to prove it. We go on endlessly about free enterprise and risk capital.

Our principal national saint is the Great Emancipator, the president born in a log cabin. Our foremost poet is the poet of the open road and the democratic vista. To this day our captains of industry celebrate the jobs they had chopping ice.

In fact, however, American society is chiefly distinguished by large institutions. Giant corporations dominate the economy. Big universities and research institutions hold the keys to learning. Most of us live -- by the millions -- in huge urban centers.

Far from the swinging free as individuals, we adjust to each other. We stand endlessly in line for films and museums. We wait patiently for traffic lights to change. We accept mutely the decision of utilities to rip up streets. We don't -- compared with most other folk -- even cheat the tax collector.

Limitation of risk is the other side of regimentation. Our great success stories in private enterprise are not bold innovators. They are careful bureaucrats.

People may drop out of school and quit jobs. But hardly anybody who genuinely wants work cannot find work of some kind. Failing a class is so hard that some states have adapted minimum achievement tests for graduation from high school. Compensatory programs have been developed for every type of American -- blacks, browns, women, the handicapped, people on welfare. For those who can't pass tests, there is a challenge to the tests. Truly, the down and out in most of American life -- the failure -- tends to be a pathological case.

Sports -- along with the arts, which have a much smaller constituency -- are genuinely different. There merit, and only merit, counts. The best athletes come to the top. The rewards they reap in money and fame are fabulous. There is no nonsense about affirmative action for short white basketball players or equal rights for women in football. Even the antitrust laws tend to be suspended so that skill can triumph.

Failures, by the same token, are also real. The aging pitcher actually does lose the hop on his fastball. Skiers who fall are out of the competition. Teams that don't take risks blow the Super Bowl.

For all those reasons, sports carry a special thrill for most Americans. There is about them the glamour of youth and the spirit of teamwork. We revel in victories and are the better for it. When the Cardinals win the pennant, St. Louis doesn't have race riots.

So it is natural that Olympic stars would feel themselves to be above politics and resent a mere presidential decision to boycott the Moscow Games. pIt is understandable that they would protest the decision, and easy to see why so many Americans sympathize with the protest. Unlike farmers and businessmen and scientists who are indemnified, the athletes really have something to lose -- and lose forever.

For my own part, I wish there were more of American life imbued with the national myth. It would be good if scientists had more self-confidence and businessmen showed more disposition to take risks. Anyway, there is reason to be glad that sports at least afford an enterprise with a mass constituency that does fit into a special enclave. As many of us feel in our bones, sports is one of the last barriers against a mindless egalitarianism, a refusal to acknoweldge superiority that is diminishing the quality of American life.