Tributes like tonight's "High Hopes: The Capra Years" could give character assassination a good name. Frank Capra, who directed some of the most beguilingly good-hearted and optimistic films in Hollywood history, deserves far better than this haphazard and numbskulled hour, and presumably will get it next year when the American Film Institute hands him its Life Achievement Award.

Those with a fondness for Capra, who always aimed not for the jugular but for the proverbial lump in the throat, would do well to avoid NBC's curiously cursory homage, at 10 tonight on Channel 4. The film clips have been tossed together in dizzy disarray, and writer Richard Schickel hands such incongruous guest stars as Carl Reiner such incisive observations as, "We can't live by cynicism alone."

How true, how true, and more's the pity.

Others who pop up include Lucille Ball, Burt Reynolds and James Stewart, who at least appeared in Capra films but whose contribution is almost self-parodistically aw-shucksy. The narration doesn't seem to sense the difference between Capra's fanfares for the common man ("Mr. Smith Goes to Washington," "Mr. Deeds Goes to Town") and his philosophically unrelated adaptations of Broadway plays ("Arsenic and Old Lace," "You Can't Take it With You").

There is an extended sequence, in which Capra himself appears (at 80 he seems alert and affable but has terrible taste in shirts), devoted to his greatest film, "It's a Wonderful Life." The print quality of the clips shown is sparklingly good (far better than the motley 16mm version recently shown by Channel 26), but it's simply not worth running the show's gauntlet of inanities and indecencies to get to it.