A marvelous thing happened over on Paul Krugman's blog at the New York Times last week. Krugman effectively conceded defeat on a range of economic debates. Who defeated him? People who posted comments on his New York Times blog. Mere commenters.

For those who do not know, Paul Krugman is one of the few who still claim that Keynesian progressivism is the answer to America's (and Europe's) problems, not their cause. He repeats that claim many times each month. Amid these repeated expressions of his "progressive" faith, he now also repeatedly expresses grim despair because his progressive policy prescriptions are being accepted less and less in the public square, even by the Obama administration.

Krugman is an academic. He has never run a company. He has never created a job. The closest contact he evidently ever had to "business" was as an adviser to Enron, where (in his own words ) he was paid $50,000 to help build Enron's "image."

This, perhaps, explains the dozen or so points that Krugman makes over and over. Here are a few: Obama's stimulus was too small . Debt is good . Austerity is bad . Deflation is coming . Ken Rogoff , Greg Mankiw , Alberto Alesina (all at Harvard), and other serious economic scientists do not understand economics as well as he does. Those who do not agree with him are " mass delusional ." And perhaps Krugman's favorite line : "I was right, of course."

Befitting his ideology, Krugman has only one policy to propose, regardless of topic: Transfer more resources from the discipline and dynamism of markets to the inefficiency and cronyism of government.

Government-run health care. Government-controlled banks. Government bailouts. High taxes. High spending. Krugman wants it all, just like in Europe (which, in 2008, he called "the comeback continent"). And Krugman has no problems denying economic science and current events to advocate it.

With the meltdown in Europe so obviously the consequence of too much Krugmanism and U.S. unemployment near 10% after a trillion dollars in stimulus, Krugman has attracted some criticism.

For example, Robert Barro, the distinguished Harvard economist, noted that Krugman "just says whatever is convenient for his political argument. He doesn't behave like an economist." The New York Times ombudsman Daniel Okrent observed that Paul Krugman has "the disturbing habit of shaping, slicing and selectively citing numbers in a fashion that pleases his acolytes but leaves him open to substantive assaults." James Taranto at the Wall Street Journal, after listing the falsities in Krugman's latest piece on climate last week, hazarded that perhaps "Krugman makes himself ridiculous merely to make our job easy."

But no matter how low Krugman's fallacious fruit hangs, Krugman has long been comfortable among the acolytes who frequently post on his blog. A representative post is: "Paul, you are a God-send for those of us who appreciate a superior intellect with common sense! Thanks for applying your brilliance." Or this : "Paul, dig deep dude. You are brilliant." It was hardly surprising that last January, Krugman declared , "I love my commenters."

No longer.

For just as Krugman was declaring his love for his blog commenters last January, people started posting serious rebuttals of Krugman's standard claims about economics. These commenters were not obviously Republican stooges. They were not obviously members of "the political class." They were not obvious ideologues.

Rather, the posters simply knew some economic science and how jobs are created and economies grow, perhaps because they were members of "the productive class." And they came prepared to support their rebuttals of Krugman's ideology and his singular policy prescription by facts and peer-reviewed economic science.

For six months, they made Krugman's blog one of the more informative and interesting places to hear economics debated. In part, this was because they gave Krugman a serious run. Their posts were long, near the 5,000-character limit set by the New York Times. They were reasoned. They were knowledgeable. They carried citations to economic science literature that one might expect in a Ph.D. dissertation.

And so their rebuttals were often decisive.

For example, when Krugman a month ago drew one of his famous "trend lines" based on a single point, a blogger named rjh immediately responded , "These trend lines you are drawing all over the place. Pardon my French, they are complete garbage." And nearly half of Krugman's commenters joined to point out that Krugman was arguing junk. Krugman was forced to make two defensive replies ; both were immediately refuted .

Responding to Krugman's praise for the high taxes in Europe and his repeated denial that tax cuts might stimulate an economy enough to make up for revenues lost, a European posting under his initials jg pointed out that the low Reagan-Clinton tax rates made "being an entrepreneur interesting again. All those internet startups like eBay, Amazon or Netscape would probably never have been created if it weren't possible for the inventors to get rich." This anti-progressive notion that the "evil rich" might actually create growth if they were not taxed -- on his "personal" blog, no less -- must have made Paul spit up his morning coffee.

But things got worse for the professor. Matching Krugman's repeated claim that the "stimulus" was too small, Sean produced peer-reviewed economic science from Alesina , who examined 92 attempts at stimulus since 1970 in OECD countries and found that tax cuts, but not spending, stimulated. Krugman stammered a reply , but the damage was done; his acolytes had learned that economic science existed that contradicted Krugman's claim (central to Obama's "stimulus" legislation) that government's spending your money helps an economy.

Matching Krugman's claim that government can "create wealth by printing money," several posters cited the latest economic science showing that the "multipliers" that Keynesians use are wrong. They further noted that Krugman had used these wrong multipliers seventeen months ago to predict incorrectly that Obama's stimulus package would keep unemployment below 9%.

And so Krugman's blog presented the most unforgivable conclusion: Krugman had actually been wrong. As he had been when he advocated low interest rates and the creation of a housing price inflation in 2001, one of the causes of current economic difficulties.

Things then got still worse. When Krugman repeated his claim that Bush's tax cuts had "caused" the deficit and damaged the economy, commenters first taught Krugman how to count. They then cited two papers by the Romers showing that tax cuts help economies. Christina Romer is, of course, the chief economic advisor to President Obama.

When Krugman repeated one of his "debt is good" posts, posters linked to the economic science from Reinhardt and Rogoff showing that high debt is inimical to economic recovery.

Occasionally, Krugman attempted a reply. For example, he dissembled that Reinhardt and Rogoff had "highlighted" a single postwar American experience, which he dismissed as "spurious." The commenters did not let him get away with it. Within 24 hours, Sean had pointed out that Reinhardt and Rogoff had found similar effects of debt in six countries on three continents over four decades, including Canada, Japan, Greece, and Belgium. Krugman then struggled to find something "spurious" about each of these. Sean 's rebuttal showed that Krugman was refusing to meet any burden of proof. Still worse, Samuel showed that Krugman's reasoning, if applied generally, would forever insulate Krugman's ideology from any refutation of any kind.

...Which is perhaps what Paul Krugman wants, but it is not economic science.

Krugman's blog commenters were especially relentless in pointing out his inconsistencies. In one post, Krugman admitted that "politicians will always find ways to shield the powerful." Posters piled on, pointing out that Krugman's universal policy prescription gave politicians more power under the assumption that they would defend "the proletariat." Krugman replied that he was "sure that there's a large literature" on government cronyism and corruption. Secure in his big-government ideology, he admitted that he had never read that literature. But like the ideologue that he is, Krugman then expressed his faith (the only word appropriate) that "bureaucracy will do a heckuva job" if it is not "downgraded and devalued." Bloggers responded by citing the latest economic science showing the impossibility of Krugman's "utopian dictatorship-by-bureaucracy."

Paul Krugman has spent his career as a pundit advocating that government bureaucrats and political process replace markets. He knows that there is a large literature that says that this is a bad idea. That literature is transparently relevant to Krugman's only policy proposal. And yet Krugman has not read it...and admits that he has not read it, without embarrassment.

By July, Krugman had lost his "Battle of the Blog." On July 23, Latrina commented , "Who is this Sean from Florida? He takes everything that [the] Professor [says] and shreds it, piece by piece. He shouldn't be allowed to post his comments on this blog since he seems to be winning all the debates. We progressives need to stick together and embellish our talking points without someone from the outside pointing out fallacies in our ideology."

Krugman had also had enough. On July 23, Krugman showed that he was clearly no longer "in love" with his commenters. Now he called them "ranters" and "trolls." On July 28, Krugman changed his comment moderation policy. Claiming that "ranters ... say the same thing every time," Krugman announced that he was going to throw away posts longer than "three inches." His thinking must have been thus: Three inches are sufficient to write "Krugman is brilliant," but not sufficient to present a documented and persuasive rebuttal to whichever of Krugman's standard arguments he was peddling that day.

Within 24 hours, those outside the Times had taken notice. Stephen Spruiell at the NRO noted the absurdity of Krugman's complaint that bloggers might use the same responses to rebut Krugman's repeated statements of the same ideology. Wrote Spruiell:

This [is] from the guy who has spent the entire summer rewriting the same blog post", Spruiell went on to point out that "Krugman's sycophants ... also say the same thing every time." "Krugman's policy seems geared to limit comments to "Yay Dr. K!" "Way to go!" "Keynes was right!" etc.

As indeed it has. Krugman's blog the day after the policy change had just six comments the last time I looked. "Hurray," said one. "Awesome!!" said another.

In his appearance on Sunday on "This Week," Krugman repeated his attack on Rogoff. He repeated his claim that he, a deflationista, "was right." Regulars could go to Krugman's blog and download the economic science that showed that Krugman was blowing smoke on "This Week," a gig that may pay Krugman more than even Enron.

And so after his ride back to Princeton, Krugman pulled the plug. He twice scolded "whiners," claiming that this blog under the New York Times masthead was "a personal not-for-pay venture." He claimed that he was burdened by needing to see if posts contained "obscenities" (none had, other than the "French" cited above). And he declared that he has "no obligation to provide" space for "ranters" and "whiners" who might rebut the ideology that he routinely markets.

Of course not. It is his blog. But it is newsworthy that after years of allowing 5,000-character responses consistent with Times policy, Krugman pulled the plug just as he was so obviously losing the debate. The academic world and the business world share something: They both view this as an admission of defeat.

Krugman is also "losing the audience." Eighteen months ago, Krugman's progressive ideology that was the consensus of the president, the House, the Senate, and not a few Republicans. Now, the Obama administration is evidently worried that it bought economic snake oil from Keynesians like Krugman. Even Ezra Klein is beginning to question the Keynesian economic models of Blinder and Zandi that "got it so wrong."

And so a six-month episode of enlightening economic debate has come to a close. Will Krugman respond to posts on other blogs? We do not know, but routinely in the past , he simply refuses to do so. He is clearly unable to do so, and, surrounded now sycophants and acolytes who tell him how brilliant he is, why should he even bother to try?