Grand Canyon.

What JFK proposes to do for our political past, Grand Canyon undertakes to accomplish for our societal present. Directed by Lawrence Kasdan from a script by himself and his wife, Meg Kasdan, this is the story of life in Los Angeles (or Anytown) today, as seen through the eyes of a handful of upper-to-lower-middle-class characters. Their lives become interconnected by such seemingly random events as a prominent lawyer's car breaking down in one of L.A.'s seamier sections, or that lawyer's wife's taking in an abandoned black baby, or a highly successful hack Hollywood producer's being wounded by a mugger, or said lawyer's extramarital fling with his pretty secretary.

From the man who gave us the vastly overrated The Big Chill, this film was almost inevitable. Whoever came up with that supposedly hardnosed but actually glossy backward look at the lost illusions of 1968, just about had to project same--or similar--characters into an even murkier future, which happens to be our present. We get the tribulations of upward mobility as a black family is arbitrarily moved to a better, white neighborhood; also the trials of--shall we call it downward immobility?--as the lawyer's car, during a nocturnal shortcut, gets struck in a black slum, and its owner very nearly finds his life cut short.

It is on of Grand Canyon's several misfortunes that this alarmingly believable episode comes at the lengthy movie's beginning, effectively dwarfing what follows. As a scary gang of young blacks surrounds, taunts, and threatens Kevin Kline and his car, racial tension, class hatred, and the precariousness of the nost sheltered existence in the urban jungle come into frightening focus. The last-minute arrival of the tow truck, driven by Danny Glover, a black man of sense, strength, and courage, is no deus ex machina, as the risky confrontation continues, more equally balanced now, but no less inflammable.

Though not uninteresting, the subsequent episodes prove increasingly pious and predictable. Especially wearing are the attempts of Mary McDonnell, as Kline's near-hysterical wife, to persuade her spouse to adopt that found baby. And Kline's office affair with Mary-Louise Parker is handled too superficially for any real impact, especially when the actress is allowed to indulge too many of her fussy mannerisms. Danny Glover's romance with a black colleague of Miss Parker's, Alfre Woodard, is not badly done, and yields the film's cleverest comic line, but the evolving friendship between Kline and Glover is routine stuff, as is the puppy love of Kline's teenage son for an adorable girl he meets at camp. Glover's nephew, who tries to run away from the upscale ambiance suddenly foisted on him, also gets relatively short shrift. And we are given much too little of that slick movie producer, played less than persuasively by Steve Martin.

In fact, Grand Canyon raises the question of whether a movie, even a longish one, can seriously undertake to examine several lives and a cross section of social problems. A hefty novel can do it, and so, perhaps, could a very long movie, which, however, would create problems of distribution. To be sure, it's not hard to deal with an even larger group of people in, say, a disaster movie, where the central problem is that burning skyscraper or sinking ocean liner. But where there is no center-stage disaster allowing for formulaic characterization, disaster of another kind takes over.

Except for Miss McDonnell's overemoting and Miss Parker's fidgeting, much of the acting is solid, notably that of Glover, Kline, Woodard, and some lesser known others. But there is, finally, something too schematic, didactic, contrived about the film, perhaps best illustrated by the concluding convergence of all the principals on the Grand Canyon, where the symbol, not content to remain a symbol, turns into a grandiose travelogue. All that's missing is Ferde Grofe's music, but then James Newton Howard's managers to be just as grand.