WHEN Johnny Carson retires from "The Tonight Show" this week and leaves us to Leno, Letterman, and the rest, what we watchers of late-night talk shows will experience is essentially a change in style - from classical to postmodern.
Mr. Carson's show was classical in that it offered a transparent window on his guests' various talents. David Letterman's show is postmodern in that the medium is partially opaque. Carson's cameras stay invisible, politely focused on the set and the guests. Letterman jostles "our" camera at some point in nearly every opening monologue. He throws pencils at us. Why? To acknowledge the artifice, to be un-phony by displaying the phoniness.
Carson always gave a genuine comic monologue. Set-up and punch, set-up and punch, weaving together today's headlines with items of sheer mirth.
Exit the mirth of a nation, enter the derision. After Johnny's classical period, talk show decadence now has its day. Letterman's halfhearted pretense at a monologue is itself a kind of joke. Even supposedly hip cynicism grows depressing after a while. Yet Johnny's show seemed to exult, perhaps more innocently than is now the fashion, in the value of life. That's probably what we'll miss the most.
Johnny's classicism may seem old-fashioned next to his successor at NBC, Jay Leno, whose snack-food ads run on MTV. But Leno is less hip than Letterman. In terms of style, that is, there's a continuum: Johnny was the classic, Leno and Arsenio Hall are modern, and Dennis Miller and Letterman are postmodern. The scale refers to the relative transparency of the medium itself.
Miller, for instance, is the only one now making a regular prop out of the studio monitor's applause sign. There and elsewhere in his new show, Miller thus adds a new kind of humor, that of text appearing on the screen, which is obviously an up-to-date style of our times. Letterman's "Top Ten List," when you think of it, is a kind of computer-screen scroll unfurling its punchlines. But let's not mistake the postmoderns' use of superimposed text as some fresh wave of intellectualism sweeping the tube: On all of these late-night shows (including "Saturday Night Live"), the hosts are still careful to read to us the text that appears on our screen.
Johnny's shows almost always were videotaped in one take, in "as-if-real" time. Led by actor Ronald Reagan's preferred film director Fred De Cordova, Johnny's producers took the show's classical unities of time and space very seriously. You could watch the show as if it were all just happening as you watched.
The newer shows, though, present themselves as things that could happen only on video. With the cameras jerking around "Late Night Thrill-cam" style, and the ("Hal, roll that tape") endemic use of videotape, postmodern TV treats time and space as stuff waiting to be spliced and diced. These newer programs, conceived since the cable explosion, have understandably been designed to simulate channel "zapping." Letterman, most notably, with his out-of-the-studio tape packages, overtly acknowledges that his sh ow's reality is not the virtuosity of as-if-live, but rather as if (because it really is) on tape.
The good side to postmodern TV's self-consciousness is that it can seem more honest, less deceptive about its illusions. The down side is that the self-consciousness leads to narcissism.
TV as a medium has developed a bad habit, recently, of casting its own shadow over the picture. We saw it in the coverage of the Gulf war, and we see it in the producers, cameramen, and stagehands who play sullen on-camera characters on Letterman. Here again, Johnny kept the screen clear for us. He had the knack Ovid admired in Pygmalion's work as a sculptor: an art that conceals its own art. Letterman's show, like much of MTV, is largely about being on TV.
But if there is a change of style between Johnny and his successors, the function of these shows, no matter who hosts them, remains the same. Their very profusion, and the impressive ratings they get, suggest that whether classical, modern, or postmodern, light entertainment with celebrities talking about themselves is what Americans prefer to watch at that hour. Stay up late and hear some jokes, marvel at some tricks, see the stars come out.
These shows perform a liturgical purpose at the end of the weekday: amusing us, reassuring us, and preparing us for sleep. Styles may come and go, but the tube - thanks largely to Carson's heroic support of the ritual - has learned, at last and at least, to do that. Thanks, Johnny, for sending us to bed smiling.