ROBERT MORRIS is a famous contemporary artist whose work is widely regarded as thoughtful and important. Visitors to the Morris show at the Corcoran may wonder why.

While billed as "the first exhibition to focus exclusively on the relationship between image and text in the work of the internationally renowned artist," the 85-object show actually is a fairly full-blown retrospective. It includes abstract paintings that haven't been seen since Morris's first solo exhibition in 1959 and there is a raft of works from his early "Crisis" series and the "Firestorm" and "Holocaust" wall reliefs from the '80s.

The 16 new paintings, completed within the past couple of years, are pretty thin. Which is not much of a surprise, because so are most of the older ones.

Morris, who's best known as a minimalist sculptor, derives his images mainly from the public domain. Nothing wrong with that, except that most of what's original in his work seems trivial, much of what's not trivial seems trite, and much of what's not trite is travesty. Presenting us with a lynching scene from the 1920s is reaching pretty far back to exacerbate social wounds; assaulting us with death-camp burial pits seems not so much to honor as to exploit Holocaust victims.

The most recent works are large encaustic-on-aluminum paintings which, curator Terrie Sultan says, are "based on the reinvigoration of experience and cognition as a way of explicitly recycling social history, and are grounded in an iconography drawn from mass media sources, art history, and the artist's own personal history."

The images are absolutely predictable and utterly politically correct diatribes against politicians, oppression of minorities, the rape of the planet, etc. The aluminum panels no doubt also are recycled.

DONALD LIPSKI and BUZZ SPECTOR, on the other hand, are a pair of witty and impudent iconoclasts whose current Corcoran show is an unalloyed delight.

Lipski likes to poke holes, literally, in our holies of holies; when he bored a hole through "The Book of Knowledge" in 1985 it was a hoot, and a brilliant stroke.

Lipski's "Half Conceals/Half Discloses" (1989) a painstakingly -- as well as "lovingly and respectfully" -- perforated 16x8-foot American flag, is a spine-tingling call to arms. His presentation is so straightforward and riveting that we cannot duck its truth: When the authorities pass laws against "desecrating" our national symbol, it's the duty of every patriotic citizen to take a flag out into the street and desecrate it.

Spector is a funster and punster whose works break people up. But you can't help noticing that as the laughter dies away it has a sort of hollow ring to it.

"Hospitalite': pour Georges Bataille" (1988-89) is verbal and visual punning on "hospital" and "hospitality," and "breadpan" and "bedpan," as well as the English and French words for bread and so forth. What it is is 11 bedpans stuck to the wall, each containing a loaf of bread that may or may not represent a baby. "L.A. Brea(d)" (1990), is a gross of loaves of French bread bound in a mile of twine and dipped in tar. "Freeze Freud" (1990) is the collected works of the father of psychiatry, frozen in a block of ice.

Curator Sultan's accompanying brochure explains what it all means, but Spector's too funny for words.

INABILITY TO ENDURE OR DENY THE WORLD: Representation and Text in the Work of Robert Morris -- Through Feb. 17.

TRANSGRESSIONS: Donald Lipski and Buzz Spector -- Through Feb. 10. Corcoran Gallery of Art, 17th Street and New York Avenue. NW. 202/638-3211. Open 10 to 4:30 Tuesday through Sunday and to 9 Thursdays. Metro: Farragut West. Call ahead for wheelchair access.