John Dean's weak conscience: an apostate Republican fails to explain today's GOP.

En route to getting shellacked by historic proportions in the 1964 presidential race, Sen. Barry Goldwater (R-Ariz.) suffered through a smear job as oversized and ugly as Lyndon B. Johnson's gallbladder scar.

It wasn't the infamous "daisy ad," in which a young girl innocently pulled the petals from a flower until a mushroom cloud filled the frame. That w spot was at least rooted in Goldwater's loose talk about using "low yield" atomic bombs in Vietnam. The truly low blow came in the pages of Fact, which claimed to have asked some 12,000 psychiatrists whether Goldwater was "psychologically fit to serve as president of the United States." Among the more than 1,800 replies were long-distance diagnoses pronouncing the challenger a "dangerous lunatic" and a "compensated schizophrenic" similar to Hitler and Stalin.

Goldwater's ghost hovers over Conservatives Without Conscience (Viking), the new study of "authoritarian" Republicans by John W. Dean. The book, whose title is a play on the senator's 1960 manifesto The Conscience of a Conservative, was conceived as a collaboration between Goldwater and the Nixon administration's most famous heretic. Dean shared the senator's dislike of the "so-called social conservatives" who have risen to prominence within Republican ranks, and the pair planned a book for which they would talk "with people like Chuck Colson, Pat Robertson and Jerry Falwell" and "attempt to understand their strident and intolerant politics."

The project was temporarily derailed by Goldwater's death in 1998, but Dean remained dedicated to unmasking what he sees as a breed of "tough, coldblooded, ruthless authoritarians" who have "co-opted" conservatism. For Dean, figures such as President George W. Bush, Vice President Dick Cheney, and former House Majority Leader Tom DeLay are not simply misguided ideologues, relentlessly pushing an agenda at odds with Dean's own, (He describes himself as a registered independent or "a 'Goldwater conservative.'") They are sinister figures uniquely deranged by their lust for power, their limited ability "to see the world from any point of view other than their own," and their willingness to submit to authority.

The book, which is dedicated to Goldwater, draws heavily on the work of the social psychologist Bob Altemeyer, the creator of a scale for measuring "right-wing authoritarian" (RWA) tendencies. Dean writes that Altemeyer is "not given to hyperbole in his scholarly work" yet quotes him as saying that many "High RWAs" would "attack France, Massachusetts or the moon if the president said it was necessary 'for freedom.'" Altemeyer says it's "a scientifically established fact" that political, religious, and economic conservatives are High RWAS, and Dean concludes that our government "is run by an array of authoritarian personalities" who are "dominating, opposed to equality, desirous of personal power, amoral, intimidating ... vengeful, pitiless, exploitive, manipulative, dishonest, cheaters, prejudiced, meanspirited, militant, nationalistic and two-faced."

The estimated 20 percent to 25 percent of us who are High RWAS, Dean warns, "will take American democracy where no freedom-loving person would want it to go." With Ahab-like monomania, he discovers that every objectionable conservative Republican action--from "taking America to war in Iraq on false pretenses" to harsh right-wing criticism of the nomination of Harriet Miers to the Supreme Court--reflects triumphant authoritarianism.

But Conservatives Without Conscience does little to advance a true understanding of contemporary politics, conservative or otherwise. Dean's schema doesn't go far in explaining, for example, the huge increases in nondefense discretionary and entitlement spending under President Bush and a conservative Congress.

Alas, even the distortions and exaggerations used to build the case for war in Iraq are hardly unprecedented. (Remember the Maine? And the Gulf of Tonkin?) What Dean sees as dark new developments read more like politics--and politicians--as usual.

As important, Dean's book calls to mind nothing so much as the scurrilous treatment of Barry Goldwater back in the 1964 campaign. Our political discourse is rancorous enough without attempting to psychologize our adversaries out of decent debate. When Ronald Reagan nominated Sandra Day O'Connor to the Supreme Court, the Rev. Jerry Falwell said every good Christian should oppose her selection. Goldwater, rising to the defense of a fellow Arizonan, responded that "every good Christian ought to kick Falwell's ass."

If the candidate nicknamed Mr. Conservative were to revisit today's political scene, he might find another target at which to swing his leg.

Nick Gillespie ([e-mail]) is editor-in-chief of reason. An earlier version of this article appeared in The New York Times. Reprinted with permission.