You know how we know the terrorists didn’t win? It’s not because we killed Osama bin Laden. It’s because we killed him and we didn’t really care.

Which is not to say that we won, either. It’s more to say it’s been a weird decade.

According to the Gallup Poll, President Barack Obama’s “Osama bump” in his approval rating was about five points and lasted about five weeks. Think about that for a second: President Obama ordered a daring SEAL raid that ended in the execution of America’s deadliest foe and the president’s approval rose five points for five weeks. The president can get five points for five weeks by switching from white bread to whole grains. He could probably get twice that from a single appearance on “American Idol.”

Consider where we were just three short years ago, when Dunkin’ Donuts was forced to pull a commercial in which Rachael Ray wore a scarf that looked, to some conservative bloggers, like a kaffiyeh. What’s a kaffiyeh, you ask? Michelle Malkin described it as “the traditional scarf of Arab men that has come to symbolize murderous Palestinian jihad.” “Good Morning America” explained the controversy to its viewers by flashing a picture of Ray next to Yasser Arafat. Yep, Yum-O and Yasser: Can you tell the difference?

(You think I’m making this up? It’s on YouTube.)

That was politics in post-Sept. 11 America, and it was the only politics I knew. When the planes hit the towers, I was 17. My first vote was in 2002, when bin Laden was the star of many political ads. And for all the talk of resolve and courage and endurance, the post-Sept. 11 world struck me as almost crazed with fear.

Young and Reckless

I was a little crazed with fear myself. I supported the Iraq War based on the argument that Saddam Hussein was an irrational tinpot imperialist who would use weapons of mass destruction the moment he got them. I’m pretty sure I actually parroted Condoleezza Rice’s famous line: “We don’t want the smoking gun to be a mushroom cloud.”

The whole episode brings to mind another line from the Bush era: Candidate George W. Bush’s admission that “when I was young and reckless, I was young and reckless.” The post-Sept. 11 reality was worse than that. When we Americans grew scared, we became reckless.

The policies that ensued haven’t lost their capacity to amaze -- starting with the trillions of dollars in tax cuts that were never paid for. Initially sold as a way to spend down a surplus, as we tipped toward recession in 2001 they were resold as the way to avoid a downturn. Many of the cuts were passed before Sept. 11, of course, but in blowing that first big hole in the federal budget, they made everything that came next all the more remarkable.

We went on to enter not just one war, but two. And we didn’t pay for either one. Nor did we pay when we added a prescription drug benefit to Medicare, nor when we decided to boost infrastructure spending. “Deficits,” explained Vice President Dick Cheney, “don’t matter.”

We stopped caring what other countries thought of us, and to some degree, what we thought of ourselves. We tortured and surveilled and dodged the courts. We derided our longtime allies as “old Europe” and fooled ourselves into thinking we could remake the entire Middle East in our image, and be showered with flowers while we did it. Looking back, the whole period feels like a fever dream.

Holiday From Rules

But we can’t quite seem to wake from it. We spent trillions on foreign wars and allowed our physical infrastructure to deteriorate and our technological infrastructure to fall behind that of the rest of the developed world. We ignored the increase in inequality and laughed off the decline in U.S. manufacturing. We fed a credit bubble that would eventually pop our economy and ran up the debt and eased monetary policy in ways that would make an effective countercyclical response almost impossible. Our problems today are not the result of Sept. 11, but they are in many ways the result of Sept. 12.

After Sept. 11, there was talk that our “holiday from history,” as George Will put it, had ended. And it had. But we understood our new world too narrowly. We declared war on terrorism and assumed that the righteousness of our struggle gave us a holiday from the normal rules of governance. It didn’t. And then our holiday from economic history ended, too.

The lesson of Sept. 11 was that we are vulnerable to foreign threats. The lesson of Sept. 12 is that we are also vulnerable to ourselves. Kids can get away with being dumb and reckless. Superpowers, it turns out, can’t.

(Ezra Klein is a Bloomberg View columnist. The opinions expressed are his own.)

To contact the writer on this story: Ezra Klein in Washington at wonkbook@gmail.com

To contact the editor responsible for this story: Francis Wilkinson at fwilkinson1@bloomberg.net