James Whitmore's solo show, built around what he calls Will Rogers' "cowboy philosophy" of national values, has returned to Ford's Theatre for its third run. That this two-hour monologue has prospered for almost eight years now more than confirms the actor's observation several years ago that "these guys some of us are doing on the stage - Fonda's Clarence Darrow, Hal Holbrook's Twain, my Rogers and Truman - can help give us a sense of what our heritage is."

This work, based entirely on fragments from Rogers' stage and literary commentaries on the politics and mores of the 1920s and 1930s, expresses an attitude of skeptical but benign humor that clearly appeals to the audiences of the 1970s.

Some examples of Rogers the social commentator:

"There's no way to keep a political party honest unless you keep it out of office."

"This country has got the greatest politicians that money can buy."

On the riducule directed at the Prince of Wales because he was a bad equestrian: "I don't see why people pick on him so. Anybody who grew up in the West like me knows that when your horse falls, you have a tendency to join him on the ground."

His wonderful parody of the taciturn Calvin Coolidge giving a State of the Union address is probably the evening's high point - fully up to the standards of the best contemporary stage parodists.

This primary appeal of this material lies in its "heritage," as Whitmore calls it. This is a properly dignified way of saying nostalgia. Rogers's humorous inventiveness and his wisdom are undeniable, but the relevance of this material to today is limited. Rogers' time was considerably more innocent than our own. And Whitmore's optimistic final line from Rogers, that despite all the kidding, "I never met a man I didn't like," would be harder for an entertainer of today to sustain in light of what has occurred in the ensuing four decades.

The one-man show has become a cliche. But Rogers was primarily an entertainer, and his lines work better on stage than in print.

Whitmore, who premiered "Will Rogers, U.S.A." at Ford's in 1970, holds things together remarkably well, considering that much of Paul Shyre's script is no more than a pastiche of one-liners. The run is scheduled for four weeks.