Richard A. Posner has spotted a vigorously growing weed in the garden of American cultural delights: the specialized academic who writes and lectures on "matters of broad public concern." In books, magazine articles, op-eds, and television appearances, this new breed of public intellectual spouts results-oriented social criticism to a general audience. The "controversialist" offenders are "often careless with facts and rash in predictions." They operate in an undiscriminating media market that imposes no costs for bad arguments, mistaken diagnoses, and false prophecies.

Posner's Public Intellectuals: A Study of Decline begins, fashionably, with a confession. "The reader may sense here the paradox of self-reference," Posner confides. "Am I not an academic public intellectual?... I was a full-time academic and am still one part-time, writing out of my field.... I am aware that the arrows I shoot may curve in flight and hit the archer." Casting his admission as a question looks like a hedge, but in a later chapter he includes his name on a systematically culled list of 546 public intellectuals. He also ranks himself among the "top 100 public intellectuals," based on media mentions. (The data are on the Web at http://home.uchicago.edu/~rposner/publicintellect.) Posner, a conservative academic appointed to a federal appeals court by President Reagan, has written many books on legal and public affairs, and on social issues such as AIDS and aging.

The book casts a wide net. The catch includes Noam Chomsky, Alan Dershowitz, Ronald Dworkin, Paul Ehrlich, Stephen Jay Gould, Paul Krugman, Martha Nussbaum, Richard Rorty, and Lester Thurow. Posner faults Chomsky for dismissing reports that the Khmer Rouge in Cambodia had killed more than a million people and never acknowledging his error. Paul Ehrlich has been "consistently wrong for decades" in apocalyptic visions such as his 1970 warning that "Americans will probably be subjected to water rationing by 1974 and food rationing by the end of the decade."

The Right doesn't get off. It failed to grasp Communism's internal weaknesses and thus couldn't imagine its implosion, Posner says. Gertrude Himmelfarb's study in national decline, One Nation, Two Cultures, idealizes the past. In his work, Robert Bork engages in "considerable hyperbole."

Posner imposes a high standard on speech, one that looks a little quaint when applied to political utterance. Sean Wilentz, a historian who opposed President Clinton's impeachment, can't be forgiven for telling the House Judiciary Committee in December 1998 that "upon this impeachment inquiry ... hinges the fate of our American political institutions." Most would understand such testimony as a passionate, agenda-driven extravagance and dismiss Wilentz's description of his statement as "no exaggeration." But Posner takes the words at face value and argues that "it could not have been clear to Wilentz" that so much depended on whether Clinton was impeached.

Posner's arguments rely heavily on sheer quantity of evidence, and their bulk is indeed persuasive. Suggestions for change, on the other hand, take up only 11 pages at the end of the book. They have the ring of dutifully composed afterthoughts and are introduced with a verbal shrug: "In the main we shall have to live with this slightly disreputable market. But what else is new?" Universities could perhaps require faculty to post or cite on the Web all nonacademic writing, but the proposal has "no hope" because "academics will denounce it as 'McCarthyite.' " Voluntary posting might work if only a few prominent professors would lead the way. And maybe academics, like public officials, could disclose all moonlighting income. Posner doesn't deal with the counterarguments—privacy, fairness—this idea would generate among academics, but he at least grants that the public intellectual, unlike the public official, has little power.

We will continue to live with irresponsible public-intellectual argument and prophecy: Pressure for change never builds because "the views of public intellectuals are not important to most people, even those who read their books and articles." Then why do readers bother? Because they are looking not only for information "but also for entertainment ... and for ... solidarity" with like-minded thinkers, a function Posner calls "rallying." In a rare sunny moment, he admits that "public-intellectual work may even be a superior kind of entertainment, the kind that provokes thought and stimulates curiosity."

Posner concludes that his arguments don't add up to irrefutable proof. "I have not proved that the market for public intellectuals is failing to deliver a product of high average quality," he says. However, he has at least "presented a fair amount of evidence that it is," though "anecdotage is not proof." What drove him to produce some 400 pages of brilliant, barbed commentary on a cultural ill that does little harm and probably can't be cured? He claims less interest in criticizing public intellectuals than in showing "that the public intellectual can be studied in a systematic and fruitful fashion." But the book is not about research methods. It's an elaborate charge of irresponsibility against particular public intellectuals and their milieu. Its underlying aspiration for a higher code of behavior among players in the media free-for-all is both romantic and legalistic. It is the surface of the book—the well-built arguments, the cutting language, the call for change—that has force. Posner has produced an archetypal public-intellectual work: It doesn't prove much, but it provokes and stimulates. It is a sophisticated media performance that entertains and rallies.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.