Does a TV pitch for soap or soda pop belong in an art museum?

That old nagging question keeps cropping up: ``. . . but is it art?'' When this was asked about motion pictures, the Museum of Modern Art helped settle the issue -- in the affirmative -- by establishing a major department to collect, preserve, study, and exhibit movies. When it was asked more recently about music videos, the museum rode to the rescue again, with an extensive show tracing the history of these rock-and-roll-and-TV hybrids.

But television commercials? That's obviously going too far.

Or is it? Could TV ads be a minor but lively subgenre of film and video art? The Museum of Modern Art seems to think so, and it backed up its opinion recently by screening the winners of the 1985 British Television Advertising Awards.

Did the 45-minute show prove the museum's case? Loosely speaking, yes -- if the ads are British, at least, and if one is willing to limit the term ``art'' to matters of style and surface alone. Many of the minispectacles feature striking bits of imagery and montage, and some are witty enough to draw an out-loud chuckle or two. Notable art-world figures took part in a few, as well: The spunky vocalizing of rocker Ian Dury sparks the ads of an electronics concern, for example, and director Ridley Scott --

of ``Alien'' fame -- directed a couple, including a delightful science-fiction extravaganza wherein the unseen denizens of a spaceship choose their favorite of Earth's soft drinks.

And yet, and yet. . . . For all their inventiveness, the things are just commercials, after all. Their only point is to pitch a product, to promote consumerism. I don't mind their brevity -- director Robert Wilson once made 100 video dramas at 30 seconds each, and they were certainly art -- and some sneak in a socially useful point, as when an appliance company speaks of ``womankind'' instead of the traditional ``mankind.'' But it would take a lot more substance than I found in these prizewinners to mak e me a student of ad art.

The awards were organized and sponsored by a British organization representing ad agencies, production companies, and TV contractors. The winners are also being screened this season at film and video centers in Chicago; Minneapolis; Los Angeles; and Berkeley, Calif.