When asked what posed the greatest challenge to statesmen, Harold Macmillan, the former British prime minister, responded, “Events, my dear boy, events.”

That’s because events tend to throw everybody off their plan. For example, Hurricane Irene ended President Obama’s vacation early. And the hurricane’s steady deterioration upset the plans of news producers who anticipated something more dramatic for their wall-to-wall coverage.

In a similar fashion, Obama and his advisers predicted the economy would do better — much better — than it has, and those predictions were wrong. The president blames events: the European debt crisis, the Japanese earthquake and tsunami, the political tsunami of the 2010 elections. Some of that is plausible, but the two years of anemic job and economic growth that preceded those events can hardly be blamed on them. An earthquake in Japan didn’t make Obama’s green-jobs initiative a bust, and the euro crisis didn’t render “shovel-ready jobs” a myth. And it’s those failures that have scuttled Obama’s plans for an easy reelection in 2012 and left him and his supporters stunned and shocked.

My National Review colleague Jim Geraghty has chronicled how, over the last few years, the media have greeted bad economic news by calling it unexpected. For instance, Bloomberg reports that “sales of U.S. previously owned homes unexpectedly dropped in July.” Reuters tells us that “consumer spending unexpectedly fell in June.” And so on.

Many who’ve been following the trend point to media bias. The press corps, writ large, wants Obama to succeed, argues American Enterprise Institute political analyst Michael Barone, so “they characterize economic setbacks as unexpected, with the implication that there’s still every reason to believe that, in Herbert Hoover’s phrase, prosperity is just around the corner.”

I certainly think there’s more than a little truth to that. The media get hooked on a story line — hurricanes are getting worse because of climate change, Obama’s a pragmatist doing the smartest things to fix the economy — and when the facts contradict the story line, it’s, well, unexpected.

But it can’t be simply media bias because the experts whom reporters call for quotes also are surprised. As Geraghty notes, groupthink is a culprit too. The guys on Wall Street use the same Keynesian computer models as the folks in the White House.

There are no more devout members of the cult of expertise than mainstream journalists. They rely on experts for guidance about what is “mainstream” and accurate and what is not. Sometimes that’s fine. Surgeons are extremely reliable sources to explain how a heart attack happens. They’re not as reliable at telling you who will have one, save in a statistical sense, and even less reliable at telling you when a specific person will have one.

That’s because prediction is hard. Experts — in politics, economics, climate — are very, very bad at telling people what will happen tomorrow, let alone next year or next century. How many of the economists who tell us what to do now failed to see the mortgage debt crisis coming? Nearly all of them.

Philip Tetlock’s 2005 book, Expert Political Judgment, documents that the predictions of even the most credentialed and experienced experts are often worse and very rarely better than random guessing. “In this age of academic hyperspecialization,” he writes, “there is no reason for supposing that contributors to top journals — distinguished political scientists, area study specialists, economists, and so on — are any better than journalists or attentive readers of the New York Times in ‘reading’ emerging situations.”

The cult of experts has acolytes in all ideological camps, but its most institutionalized following is on the left. The Left needs to believe in the authority of experts because without that authority, almost no economic intervention can be justified. If you concede that you have no idea whether your remedy will work, it’s going to be hard to sell it to the patient. Market-based ideologies don’t have that problem because markets expect events in ways experts never can.

No president since Woodrow Wilson or Franklin Roosevelt has been more enamored with the cult of expertise than Obama. That none of his economic predictions have panned out is not surprising. What is surprising is that so many people are surprised.

— Jonah Goldberg is editor-at-large of National Review Online and a visiting fellow at the American Enterprise Institute. You can write to him by e-mail at JonahsColumn@aol.com, or via Twitter@JonahNRO. © 2011 Tribune Media Services, Inc.