Robert L. Bartley died last week. He was a loving husband and father, a loyal employer, and something of a genius of a newspaperman. His proudest boast, that for 30 years he had run "the only editorial page in the country that actually sold newspapers," was unconditionally true. For more than a million readers, it was the only must-read of the day.

But it is also the case that, as an editorialist, more than any other, Bob Bartley was a corrosive force in American life. Almost single-handedly, he made extremism respectable.

It is important to understand how that happened, and what it portends.

He was born in Marshall, Minnesota, in 1937, and raised in Ames, Iowa, where his father was a professor of veterinary medicine. He attended college there, at Iowa State University, served in the Army Reserve, and obtained a master's degree in political science from the University of Wisconsin before going to work in 1962 in Chicago for The Wall Street Journal. Three years later he joined the editorial page, becoming its editor in 1972.

His career merits the attention of a careful and perpendicular biographer. Having voted for Lyndon Johnson over Barry Goldwater in 1964, he turned away from Johnson, turned away, too, from Richard Nixon, in the course of a conversion that is too little understood.

In the 1960s and 1970s, there were many currents running in the new conservatism. Among other places they found expression in magazines such as The Public Interest, Commentary and Encounter. There was in fact a Movement, or at least a Counter-Movement in those days. Much of it had little to do with the press. But under Bartley's leadership, the editorial page of The Wall Street Journal gradually gained currency and the others lost. Just at the moment it was about to pass in front of the reviewing stand, Bartley had appeared at the front of a great parade.

Trouble is, Bartley (and his then-sidekick, editorial writer Jude Wanniski) had become enthralled by a pair of rogue economists, Arthur Laffer and Robert Mundell. Having fled the complicated methodological battles that had begun in the department of economics at the University of Chicago in the 1970s, Mundell and Laffer became convinced that they had discovered a workable "supply-side" policy against inflation. Quite untethered by professional norms, they prepared to sell their ideas to the public, with Bartley and a few others serving as intermediaries.

Never mind tight money; Paul Volcker and Ronald Reagan had come up with that on their own. Never mind tax cuts; the rationale for those went back to John Kennedy, during whose administration Mundell had toiled as a young post-doc at the International Monetary Fund. The emphasis on lowering marginal rates was probably useful and certainly new. But Mundell's real secret weapon for stability (and thus Bartley's) was the gold standard -- then, as now, an antiquated and essentially crackpot scheme.

In international security matters, Bartley did better. Strategist Albert Wohlstetter may have been his chief guru, and much of his writing on the Soviet Union seems prescient. His biggest embarrassment was a noisy crusade against "Yellow Rain," a campaign of biological warfare that the Soviet Union was alleged to be conducting against tribesmen in remote areas of Southeast Asia in the late 1970s. The "Yellow Rain" samples proffered by the State Department turned out to be bee feces, dropped by swarms during seasonal cleansing flights. No credible alternative weapon delivery system was ever produced.

But Bartley's dogged refusal to grapple with his critics' claims, or to back off his original charges after the government retreated and even the news pages of his own newspaper reported that the case had all but collapsed, became a metaphor for his tendency to put his fingers in his ears and raise his voice when contradicted by the evidence. And when an antagonist produced irrefutable evidence that Bartley had been right about another Soviet germ warfare controversy, the accidental anthrax epidemic in Sverdlovsk, Bartley ignored that evidence too. The fingers stayed in the ears.

(For an a glimpse of a somewhat similar controversy between heterodox and established opinion on an otherwise unrelated manner, see the cover story on nanotechnology is an issue of Chemical and Engineering News earlier this month. It takes the form of an extended exchange between K. Eric Drexler of the Foresight Institute in Palo Alto, Calif., and Professor Richard E. Smalley of Rice University.

(Drexler is the author of a famous 1986 book, "Engines of Creation: The Coming Era of Nanotechnology," in which the possibilities of molecular manufacturing were introduced to a wide audience for the first time. Drexler, a Massachusetts Institute of Technology Ph.D., anticipated the possibility that the "molecular assemblers" he envisaged might eventually pose a threat to human control. He established his Foreight Institute to warn against the possibility, and other technology gurus have followed suit: Michael Crichton in the science fiction novel Prey, and Sun Microsystems chief scientist Bill Joy in a widely-read article in Wired magazine called "Why the Future Doesn't Need Us."

(Smalley, who won a Nobel Prize for discovery of the 60-atom carbon molecules now known as fullerenes (after architect Buckminster Fuller), has pressed for a decade dor a coordinated national research program in nanotechnology, on grounds that potential benefits of concrete applications are very great. But his has disparaged Drexler's alarms on scientific grounds. Their disagreements are laid out a lengthy point-counterpoint forum that permit you to decide for yourself with a fair degree of confidence, even without a background in physics and chemistry. As it happens, it was a similar exchange in C&E News 20 years ago that did the most to deflate the "Yellow Rain" controversy.)

The point is, such differences of opinion among periphery and the core in science are not all that unusual. Usually some narrowing of the distance takes place within a relatively short period of time, as tests are devised, challenges posed, experiments made and assessed.)

But not with low-brow "supply-side economics," any more than in the matter of "Yellow Rain." Having allied itself with heterodox opinion in economic matters, The Wall Street Journal editorial page resolutely remained there, peddling a grotesque caricature of Keynesian doctrine in which tax cuts rather than deficit spending are continually necessary to prod an otherwise stagnant economy, proclaiming at every stage that the medicine was working. ("The triumph of faith over observation," as MIT's Robert Solow slyly put it to The New York Times last week).

Bartley excoriated Reagan economic adviser Martin Feldstein for his concern about the harm of long-term budget deficits (though Feldstein continued to write for the page.) He beat up on President George H. W. Bush, especially after he agreed to raise taxes slightly on the even of the first Gulf War, in order to strengthen America's financial position. Combined with the effect of H. Ross Perot blistering away at the significance of the deficit from the other flank, Bartley's rancor helped cost Bush the 1992 election. (The Journal's preferred candidate in 1992 was Congressman Jack Kemp and, in 1996, magazine publisher Steve Forbes.)

And when Bill Clinton was elected, Bartley turned on him with vitriol not seen in mainstream public discourse since the early days of the Republic. Legend around Journal headquarters is that Bartley greeted Clinton with open arms. That's bunk. From the beginning, the editorial page was on him with no holds barred, with the aid of enthusiastic readers in Arkansas (an editorial page is "a community venture in which the audience participates," as Bartley freely acknowledged).

The irony is that it turned out Bartley was right. Clinton was, in some deep sense, accustomed to playing fast and loose. He sought to staff his administration with personally loyal retainers concealed behind professional managers. (Roger Altman at Treasury, Webster Hubbell at Justice). He immediately set about reversing the single proudest achievement of the Reagan administration, the 1986 tax act with its two brackets and few loopholes. He appointed his wife to revamp the 15 percent or so of GDP that was the health-care sector, more or less secretly and single-handedly.

But by ceding Clinton none of the prerogatives of leadership, by offering him the benefit of no doubt, by hounding him and his associates without mercy, they made him both more nimble politically and more evasive. In 1992, Bartley published his paean to the "supply-side" policies that he helped devise, "The Seven Fat Years: And How to Do It Again," just before the Clinton administration put in train the first of its ten even fatter years. The Democrats' success with the economy seemed only to infuriate him. By the time impeachment proceedings began, the cutting edge of virtually the entire apparatus of government had been politicized by Bartley's relentless editorials -- courts such as the Washington, D.C. Court of Appeals and agencies such as the FBI included.

Worse, for all its skyscraper canyons, New York City is a small town. The New York Times in the mid-1990s had passed into the hands of an impressionable and insecure publisher, anxious to make his mark. There is some reason to think that Bartley's spectacular success drove The Times' editorial page to adopt a similar strategy, in hopes of assembling an equally attentive and influential audience. Under its editor, Howell Raines, The Times editorial page, too, began taking increasingly pugnacious positions. Usually they were opposite those of The Wall Street Journal, but, on the subject of Bill Clinton, for example, often they were the same and sometimes even more shrill. In due course, Raines moved up to run the entire newspaper -- with famously bad results.

At the end of last year, Bob Bartley formally retired to write a column. Columnist and long-time editorial writer Paul Gigot replaced him. In all respects, the editorial page has become a less aggressive and more tolerant place. The wishes of the Bancroft family, which owns around 40 percent of Dow Jones, appear to have been observed. (In a recent New Yorker article, family trustee Roy Hammer told Ken Auletta that most of the family "would have preferred a less acerbic editorial voice," but that nobody had "intruded" their judgment during Bartley's reign.) The many men and women who Bartley trained have settled down to run the shop, or have taken their skills to other newspapers. The industry is better off for the diversity of opinion they represent.

Last summer, Bartley let loose one last blast. "I think we're coming to the end of an era of 'objectivity,'" he wrote, a culture that had prevailed in journalism at least for as long as he had been in the business. Only certain types of persons want to be journalists, he asserted, and inevitably they converged to an astonishing uniformity of view. Editors could lean against this tendency to produce a single outlook, but ultimately they were doomed to fail. "Since they are increasingly dealing with subjective opinion, they should stop wearing 'objectivity' on their sleeves."

Appearing in a newspaper that, throughout the period of time he worked for it, set the industry standard for clear and persuasive explanation, this was vintage Bartley: plausible and egregiously wrong. Time and again, the news pages of the Wall Street Journal undermined Bartley's more extreme positions, and those of other crusaders, too, and doing so, earned readers' trust. Of course there were occasional failures, too. Its coverage of the insider trading scandals of the 1980s is now believed to have missed the point. But during the years when Barley ran the world's most influential opinion page, the news pages of The Wall Street Journal produced steadier, more dependable, less stroboscopic illumination.

The remarkable thing is that Bartley in those years was so often right. In fact, he was usually right -- yet the air of utter certainty with which he delivered his opinions undermined the receptivity to them in some large fraction of his audience, and excited the baser instincts of some other part of the whole. The result was to move the scrum, to change the consensus, but at considerable cost to civility.

And therein is the key to understanding Bob Bartley. The man who most nearly resembles him these days -- the writer who inherited his knack for galvanizing simplicity and clarity in writing, for polarizing self-righteousness and contempt in analysis -- surely is Paul Krugman of The New York Times. Certainly he offends those on the right who do not agree with him as deeply and routinely as Bartley ever offended those on the left.

Yet already there is something unmistakably passé about the debate. It is as if we know the outcome. A centrist Democrat will retake the White House, either next year or in 2008, and life in the modern mixed economy will go one as before.

It is hard to judge writers like Bartley and Krugman apart from the spirit of their times. It may be that extremism is something of a virtue when convictions are swiftly changing all around. Pick a simple principle and stick to it -- "free markets, free men" is the charge Bartley was given, and he put it to work.

But the revolution, whatever it was, is pretty much over now. The centrality of markets has been re-established, not just in the industrial democracies, but all over the world. It is time to start mopping up.