When it comes to celebrities, Americans lose all sense of proportion. We savor even their most inane acts and words. So Bill Cosby certainly could not have been surprised when his rants on the black poor last year--"Ladies and gentlemen, the lower economic people are not holding up their end in this deal ... These people are not parenting"--became a diatribe heard around the world.

Following his surprisingly truculent speech last year at an event commemorating the 50th anniversary of the Brown v. Board of Education Supreme Court decision, Cosby launched a tough-love tour, delivering his unvarnished message of uplift and condemnation to black communities across America. "You young males, you can't just knock up five, six girls and then not take on the responsibility of fatherhood," he lectured young men. And he castigated unmarried mothers for living wildly: The child "hears you having sex in the room, he hears you arguing, he hears you cursing ... And then four days later, you bring another man into the house."

Many people, including this writer, criticized Cosby for aiming too narrowly; for refusing to deal with the range of influences that made certain inner-city residents act the way that they sometimes do, and for not offering much in the way of solutions. Now Michael Eric Dyson, the scholar and cultural critic, has taken that critique several steps further. He has done Cosby the honor of considering his words at length and seriously--much more seriously than they deserve to be considered. Disservice might be the better word; for Cosby's clearly simplistic observations cannot stand up to such critical assault.

"Is Bill Cosby Right?" (Basic Civitas Books) is a fascinating journey through black thought, American history and the psyche of an uptight, easily embarrassed, tittering black aristocracy that, in Dyson's view, has unfairly heaped blame on poor, defenseless blacks ever since the Great Emancipation. The title of his book notwithstanding, Dyson thinks Cosby is anything but right. And although the author is scrupulously fair and polite in arguing his case, he makes it abundantly clear that he sees Cosby as a hypocrite and a danger.

Dyson longs for the man glimpsed in an old Playboy interview and in Cosby's doctoral dissertation: a man who courageously stood up to racism. That Cosby--the good Cosby, the Cosby who could have been--in Dyson's eyes, was unabashed in defending his less fortunate brethren. But as Dyson sees it, Cosby caved. For the most part, the superstar comedian opted not to take stands that could potentially alienate his white fans--fans who worshiped him, in large measure, because he was a funny, almost raceless man who helped them forget that, in the real America, blacks were far from equal.

Dyson also calls Cosby on his own moral failings. Since Cosby's behavior sometimes has been less than that of a moral exemplar, he should have a little more compassion for those whose lives have been so much more difficult than his own, argues Dyson. While he does not exactly call Cosby a racial turncoat and Uncle Tom, Dyson sees him as something considerably less than a courageous figure. Instead, he sees much of Cosby's life as a wasted opportunity. For Cosby, he maintains, could have made a much larger difference in solving (or at least highlighting) America's racial problems than he has. Instead the comedian let whites off the hook.

In truth, most whites let themselves off that particular hook long before Cosby got around to doing it. It has been a very long time since whites, en masse, have appeared eager to take responsibility for the ills of America's inner-city ghettos.

Although Dyson does a brilliant job dissecting and demolishing Cosby's rhetoric, it is far from evident that Cosby's words have had anything like the impact Dyson, and so many others, seem to believe. Yes, Cosby got a lot of people talking, black and white alike; and, yes, he raised anew questions of personal versus societal responsibility that are as old as social thought. I have no doubt that Cosby's efforts are sincere; but I am not convinced that he changed many hearts or minds, or made people's lives either easier or harder.

Many young black people to whom I talked when Cosby's comments were in the news, responded to them with the same icy disdain they sensed that Cosby felt for them. As one young ex-offender put it, "He's saying the same s--- that people been saying for a hundred years, that basically black people ain't s---. He's talking about me holding up my end of the bargain. Listen ... I robbed 'cause I was hungry ... If he's going to put food on my table, if he's going to give me time to pursue education vigorously, then fine. But if he's not, then I'm going to hold up my end of the bargain and make sure I get something to eat."

That young man was precisely the sort of person Cosby presumably was trying to reach: an endangered soul adrift in a world offering him few options for success. To him Cosby's words were worse than irrelevant. The one-time stick-up man may have been less eloquent than Dyson in his dismissal; but his analysis was bracingly realistic--which, is to say, he had no illusion that the clangorous traveling Cosby show had much of anything to do with him.