Popularity - the art of biting the marshmallow bullet

A friend noted that President Reagan's popularity had slipped a bit in the polls. Up, after Grenada. Then down four or five points again - who knows why? Our friend is not a Reagan fan. But he was moved to remark with some passion: ''Popularity! The bane of America!''

He has a point. Popularity - as in ''anxiety about'' - can make life one long adolescence.

Popularity tyrannizes first of all by its very vagueness. Nobody knows exactly what popularity is. Certainly nobody knows how to get it.

Yet how the craving for it can bully and humiliate!

Popularity is the ratings report that makes everybody feel like a sitcom up for renewal.

The same day that the little dent in Mr. Reagan's popularity was reported, the word ''popularity'' turned up in another headline in the New York Times - as in ''fears about.'' The article restricted itself to quoting teen-agers on the pressures they felt to please their peers - a topic as agonizing as it has become banal.

In fact, popularity is one of those problems so sensitive that adults like to pretend it exists only for The Young.

Certainly the high school yearbook seems to bring the first 17 or 18 years of life to a false point in the climactic vote for the most popular boy and girl in the class.

Enlightened parents and other adults decry the superficial value of popularity. Popularity, they advise, is bland. Popularity is vanilla. Popularity measures merely the negative state of not-offending.

Enlightened parents and other adults teach children to stand by their convictions, no matter what.

But at the bottom of this ''To-thine-own-self-be-true'' speech, there lurks in small print the hope that, in the end, those principles will win for one's children, well, genuine popularity.

And what does that desperate little footnote say about our own dependence on popularity?

In democracy, if one is not very alert and very strong, popularity becomes the ultimate vote.

Our fascination with popularity may be gauged by the fierceness with which we fight the temptation in our children's lives openly, in our own lives secretly.

When we enlightened parents and other adults have to make a difficult decision - have to bite the bullet, as we say - we are apt to cite another cliche: ''Life isn't a popularity contest.''

The grim resignation with which we deliver the line says nearly the opposite.

The official code stays in place - barely. It is considered vulgar to court popularity. Nobody would boast that he or she had been the most popular student in the class. Far more chic to recall yourself as shy - a loner! The approved pose is that of someone who doesn't really much care what other people think.

''I'm learning to like myself'' - this is the current catch phrase. But something subliminal within the defiance seems to whisper: ''And you're supposed to like me for that too.''

The desire to be popular is devious. Is it ever possible to free oneself from wanting to be liked - by friends, by strangers, by everybody?

It's certainly an uphill struggle for Americans. Why have we bought all this self-help literature all these years on ''How to Make Friends''? Half the answer is a dream of success. Half the answer is a dream of popularity. Half the time we can't tell the difference.

The national ideal remains self-reliance. But we keep taking those cheating looks sideways - at polls, at ratings, at the whole apparatus of ''What's In.'' Television, radio, and the press make us so instantly aware of what other people are thinking and doing that we can end up living our lives like mirrors reflecting mirrors, noting what is popular, and calculating what effect any deviation on our part will have on our own popularity.

How can we break the vicious circle? Perhaps we could begin by admitting to ourselves that popularity is not just another teen-age problem. In our friend's phrase, it can be the bane of the nursing home as well as the kindergarten sandbox - of ordinary people as well as politicians and prom queens.

Then, if we want to be literary about it, why not go one step further than Polonius's speech on being true to thine own self whenever the topic of popularity comes up? We could repeat to our children (and ourselves) Chekhov's ringing declaration: I will not be a slave.m

If that doesn't square the shoulders, what will?