FEW things can be more sobering than thinking about humor, especially when that product is in precious short supply. Nobody, it seems, wants to be a comedian these days. Comedy is regarded as an entry-level job on the way to being an actor, with acting regarded as the wild-card route to politics.
One-time comedians like Chevy Chase, Eddie Murphy, Dan Aykroyd, and Bill Murray practically constitute a repertory acting company - the ''Saturday Night Live'' deserters.
At the moment, Murray is actually trying to bring tears to our eyes in ''The Razor's Edge,'' portraying a humorless chap portentously seeking to become a saint in India.
Just last week Steve Martin joined the wipe-that-smile-off-your-face crowd by confessing to an interviewer that he couldn't cut it up any more as a ''wild and crazy guy.''
As he intimated in ''Stardust,'' Woody Allen sees himself being dragged, kicking and screaming, to play it again for laughs, Sam. If his fans would leave him alone, he would prefer to make Ingmar Bergman-style films like ''Interiors'' and brood about death, as in his movie of the same name.
Even comic-strip cartoonists want to go tragic, like Gary Trudeau, who can't get ''Doonesbury'' unstuck from a gloomy preoccupation with That Man in the White House.
Amid this drought, the comedy-starved consumer, shopping for something more than laugh-track sitcoms, is left with memories or reruns, such as the anthology hour put together last month by Johnny Carson from a couple of decades of tapes of guest comedians. But where are they, now that we need them, the comedians and comediennes, of other years? Must Lily Tomlin and Gilda Radner play Ophelia?
When comedy has to rely on the oldest members of the club - George Burns, Bob Hope - the problem would appear to be more than just a case of burn-out here and there. A bystander can get a very unfunny feeling that our comedians have lost their grip, not on humor but on what exactly is funny about our times.
The cartoons of The New Yorker magazine collectively serve to support the point. Functioning as a shrewd and intelligent observation post on the commuter lines between Manhattan and affluent suburbia, the New Yorker cartoon continues to record moments of upper-middle-class rue. But the scenes have begun to freeze into a time warp. A recent issue played out a Julia Child joke, a Donald Trump joke, a shaggy (but thoroughbred) dog joke, and the oldest standard of them all, the grump-in-the-boardroom joke.
These are jokes about jokes rather than jokes about life.
It says something, too, that David Letterman, the most gifted comedian on television today, builds a lot of his jokes around old TV programs, just as Steven Spielberg builds a lot of his movies around old movies. The pop-culture quote, plus a touch of parody, equals the in-joke. Are in-jokes - jokes under glass - good enough?
Well, what are we all waiting for? Another preppie joke? Another yuppie joke? Another computer joke? Spare us! But not so long ago comedians played sharpshooter on more than just the straw targets of kitsch. Mort Sahl, with rolled newspaper in his hand, made politicians fair game. Mike Nichols and Elaine May shot bull's-eyes through the pretensions of young elitists affecting intellectual chic. Until he self-destructed, Lenny Bruce raged erratically but often brilliantly against every odd and disturbing aspect of American materialism, as he saw it, including himself.
Materialism - this, in the end, has been the primary target of the American humorist, from Mark Twain on, railing against the Gilded Age. When comedians have found the enemy in their sights, they have been content, even proud, to remain comedians. When, on the other hand, comedians change vocations, it is a sign of more than just a confused state of humor. What they - and we - are having trouble zeroing in on may be, not the jokes for the '80s but the idealism behind them, without which every joke tends to become the epitaph for a lost conviction.