NBC tonight devotes 90 minutes of presumably lucrative television time to a wide-ranging discussion of the condition of blacks in current American society. If the network set out to flex its research muscles, it should go back to the barbells, for there is little new information here and Garrick Utley's conclusion -- that "America remains in many ways two nations, black and white" -- is indefensibly obvious.

But the "NBC White Paper: America -- Black and White," which airs at 9:30 on Channel 4, does serve as a remarkable mirror to our troubled but eloquent society, reflecting the extraordinary ability of Americans to play themselves without rehearsal or script when the television occasion demands.

In Rosedale, a section of Queens that borders the promised land of Nassau County, Long Island, the camera meets a man named David Fleming and joins him while he drives his 8-year-old son to baseball practice. Fleming is black, but he says "basebawl" just like his white neighbors. His attitudes and income are middle-class. He is handsome and well-spoken and he does not seem surprised to find a camera in his car.

Fleming and the camera later attend a local school board meeting, where white residents are outnumbered by blacks and have recently lost a battle to maintain a white majority in the public school. Tempers flare. Fleming rises to denounce the white residents as "bigoted racists, whether sitting here or wearing white sheets in alleys."

Whites respond equally passionately, and there is even a dramatic scuffle for control of a microphone. Neither side is cowed by the presence of a network crew. As a white woman leaves the room, she pauses to address the camera in a Shakespearean aside: "This is what they call white supremacy?"

The scene shifts to Sag Harbor, at the other end of Long Island, where Earl Graves, publisher of Black Enterprise magazine, is introduced as an example of black empowerment. Graves, the blue Atlantic sparkling behind his estate, is eloquent, relaxed and perfect for his role. He points out that despite some political achievements (there are now 182 black mayors and 18 black congressmen), blacks control only 3 percent of all the business enterprises in America.

Thence to Harvard, where an extraordinarily attractive student explains the difficulties of being young, gifted and black; or tries to, for her situation appears to be so rare as to make her experience virtually untransferable. She is concerned about quotas for minority students, but seems quite unconcerned that a camera has followed her to lunch. A white student, interrupted outside by a TV camera, which catches him in full Wasp profile, declares that he is "ah, against quotas."

The Murphy family of Detroit, a tragic example of a living, suffering social cliche', is visited next by the roving network eye.

Mrs. Murphy is an obese black welfare mother living in a five-room house. She has been on welfare for 30 years. She has had 12 children. Three are dead, one is in jail and none of the rest has a job. She tells the camera her story, tears flooding from her eyes as she explains about her husband.

"He's just like one of the children in the house. Alcoholic. He ain't no good. I'm just telling it like it is. It's all just too much strain on me, that's all."

Several of her sons are interviewed, as are other neighborhood youths. One young man is an aspiring singer. He sings for the camera. Another is an aspiring cartoonist, who confesses that he must first learn to read. The camera shows him in a reading center, unable to pronounce the word "about."

Excellent performers all, no hint of nervousness, or even of suspicion. Maybe an artist's agent will see the singer, and his phone will ring; perhaps the glimpse of a cartoon on national TV will bring opportunity to the cartoonist. And for Mrs. Murphy herself, with no hope -- the electronic stage seems at least the chance to offer others the example of herself.

In the face of these willing subjects, a segment on a black professional, who uses a confrontational technique to challenge the racial presumptions of white youths ("You're a fool, boy!), falls flat and fake. Mere technique seems unable to compete with real people willing to perform for us the message of their lives.

And how remarkably skilled these subjects are at portraying themselves! When Edward R. Murrow's camera visited migrant workers almost 30 years ago for the documentary "Harvest of Shame," it found them frozen, respectful, even brave in the face of the lens. Of course, they had not watched television, and television had not watched them.

It appears now that when a television crew asks a question, it often gets a form of television back as an answer. This is an engaging example of cultural entropy, which gets nobody off the hook.