Television, it was originally thought, would enrich American culture. Now we're lucky if, on occasion, TV merely documents the enrichment of American culture in other fields. However, when that documentation is as festive and moving as "The Kennedy Center Honors," a CBS special at 8 tonight on Channel 9, it's almost enough to make TV look beneficent and full of promise again.

For two hours, anyway.

When it was inaugurated five years ago, the "Honors" project seemed just a gratuitous new addition to TV's endless parade of tribute and awards shows, albeit one of a more hoity-toity bent. But last year's celebration was splendid both in person and on the air, and this year's, while not perhaps as shimmering, is also entirely applaudable. Producers George Stevens Jr. and Nick Vanoff work something like a miracle with this show, and tonight's scheduling makes it a Christmas gift to the country that shows off Washington, deceptively perhaps, at its best.

One especially admirable thing about the "Honors" is that it isn't schlocked up for TV. For instance, there's no bellowing billboard at the opening telling what "stars" are going to appear, and the cast is not padded with those ubiquitous TV "names" who are added to the rosters of similar programs because they get good demographics or have high TVQ's.

On the other hand, the producers and director Don Mischer may go a little overboard in the dignity department. The spoken tributes to honorees still sound uncomfortably like eulogies to the living. Tonight's program doesn't really come to life as television until Lionel Hampton storms the stage of the Opera House with "Air Mail Special." Mischer, apparently liberated by jazz, suddenly feels free to cut and shoot much more energetically than during the previous half hour.

Another problem with this year's "Honors" is the absence of humorist Art Buchwald, who reportedly could not appear because of scheduling conflicts. Buchwald's irreverence was just what the show needed last year, and just what it needs this year. Producer Stevens says he's confident Buchwald will appear at next year's show.

The five honorees, in order of honoring, are George Abbott, Lillian Gish, Benny Goodman, Eugene Ormandy and Gene Kelly. The salute to Goodman includes not only Hampton's rouser but also a haunting, veritably celestial version of "Where or When?" by the great Peggy Lee, still mercurial after all these years and, with spangles and beads dripping from her hair, looking like a fat lamp, a Tiffany.

Not much of consequence was cut from the live show, which ran about 2 1/2 hours. One of Peggy Lee's songs went, so did one of Hampton's numbers, the film clip of the complete "Singin' in the Rain" number has now been edited (ooh, will that ever make Gene Kelly burn), and Claudette Colbert's flubbed-up pitch for the Kennedy Center has been reshot and edited in to look as if all went well the first time.

The program opens with a dispiriting downer, a dull number from the Broadway musical "Cats" (this is the big smash hit of 1982?) but then picks up with special lyrics to "You Gotta Have Heart" from Abbott's "Damn Yankees," sung by a stellar quintet: Eddie Albert, Tom Bosley, Van Johnson (particularly chipper and welcome), Hal Linden and, in rare voice, Jean Stapleton. All have appeared in Abbott shows.

Leona Mitchell sings from "La Bohe me" for Gish, who once starred in a silent film version of the story, Isaac Stern plays Mozart for Ormandy, and Kelly is saluted first by singer and dancer Gregory Hines and then by Donald O'Connor and Cyd Charisse, who costarred in "Singin' in the Rain," and Betty Comden and Adolph Green, who wrote it. And everyone is saluted by the host of the program, Walter Cronkite, who gets a round of applause from the audience when he says near the conclusion, "The show will go on, for that's the way it is." Yes, Walter, we remember.

Among those glimpsed by cameras in the audience: Roger Mudd, Dan Rather, Secretary of State George Shultz, Sens. Charles Percy and John Glenn, Ethel Kennedy, Cliff Robertson and Dina Merrill, Van Cliburn and, apparently sharing the presidential box, CBS Chairman William S. Paley. Mark Fowler, chairman of the Federal Communications Commission, has a very nice seat right up front; he was a guest of the CBS Television Network. President and Mrs. Reagan look just fine. It's audacious of Mrs. Reagan to wear a red dress in, of all places, the utterly red Opera House, but she brings it off.

Now, is this just a big fat-cat social shebang or does it really have something to say about the creative process and the inestimable value of the arts to a society? It really has something to say. In saluting Lillian Gish, Eva Marie Saint recalled the counsel given Gish by pioneering film director D.W. Griffith, who had told her, "What you get is a living; what you give is a life." Viewers will not see this, but as Stern played Mozart, a CBS cameraman on stage lowered his black-draped camera almost to the floor for a better shot of the soloist and so had to get down on his knees to see through the viewfinder. This was a dreamy, if bizarre, image of technology kneeling in the service of art -- there was something sublime about it, and there's something sublime about the program as well.