War is a cultural event. World War I destroyed the old social order in Europe and disillusioned a generation of talented young Americans. World War II bred a feeling of American unity and self-confidence. Vietnam helped trigger a counterculture.

The Iraq war is not going to have that kind of pervasive cultural impact, but it has already shifted the zeitgeist. There has been a sharp drop in Americans' faith in their institutions. Trust in government has fallen back to about half of where it was in 2001. More Americans believe government is almost always wasteful and inefficient, according to surveys by the Pew Research Center.

There has been a sharp decline in support for the United Nations. There has been a sharp rise in the number of people who say the United States should mind its own business when it comes to world affairs. Isolationist sentiment is about where it was just after Vietnam.

Americans are increasingly cynical about politics and their parties.

Only 24 per cent say the Republicans represent their priorities, according to an NBC/Wall Street Journal poll, and only 26 per cent say the Democrats do.

The hammer of disapproval has fallen hardest on the Republicans, of course, but the public is just as eager to think the worst of the Democrats. Seventy per cent of Americans say Democratic criticism of the war is hurting troop morale, according to a poll by RT Strategies. Most Americans cynically believe Democrats are levelling their attacks on the war to gain partisan advantage, while only 30 per cent believe that they are genuinely trying to help U.S. efforts.

Finally, a brackish tide of pessimism has descended upon the country. Roughly two-thirds of Americans say the country is headed in the wrong direction. Iraq is not the only issue that is driving this sour pessimism, but it is the main issue.

And Americans are in this awful mood despite rising consumer confidence and strong economic growth.

In this atmosphere of general weariness, the political pendulum is no longer swinging on a left-to-right axis. As Christopher Caldwell noted recently in The Financial Times, the same phenomenon is striking country after country: the governing party sinking, but the opposition party not rising. Problems on the right do not lead to a resurgence on the left, or vice versa.

In other words, the Democrats may win elections in 2006 or 2008, but that doesn't mean they will have the public's confidence or a mandate for change.

In this atmosphere of exhaustion, the political pendulum swings from engagement to cynicism. When polarized voters lose faith in their own side, they don't switch to the other. They just withdraw.

The chief cultural effect of the Iraq war is that we are now entering a period of skepticism. Many Americans are going to be skeptical that their government can know enough to accomplish large tasks or competent enough to execute ambitious policies.

More people are going to be skeptical of plans to mould reality according to our designs or to solve the deep problems that are rooted in history and culture. They are going to be skeptical of our ability to engage with or understand faraway societies in the Middle East, Africa or elsewhere.

In theory, skepticism leads to prudence, not a bad trait. But when it is tinged with cynicism, as it is now, it turns into passivity. In skeptical ages, people are quick to decide that longstanding problems, like poverty and despotism, are intractable and not really worth taking on. They find it easy to delay taking any action on the distant but overwhelming problems, like the deficits, that do not impose immediate pain. They find it easy to dawdle on foreign problems, like Iran's nuclear ambitions, rather than confronting them.

As Harvard economist Benjamin Friedman has observed, Americans begin social reforms when they are feeling confident, not when they are weary and insecure.

Already, the resolve to rebuild New Orleans and seize the post-Katrina moment has dissipated. The bipartisan desire to do something ambitious about energy policy is going nowhere. Even the problem of Darfur evokes little more than sad sighs and shrugs.

What's at stake in Iraq is not only the future of that country but also the future of American self-confidence. We may have to endure a cycle of skepticism before we can enjoy another cycle of hope.

David Brooks is an op-ed columnist at The New York Times.

Commentary:
I watched a bit of McCain on "Meet the Press." Talk about somber - he sounded like he was giving a eulogy for the GOP. Dems need to be the party of optimism, exuberance and ideas. After tax cuts the GOP became the "don't blame Bush party" and hasn't had an original idea since.

Dems can pick up on the idea that ‘every problem created by man (Bush) can be fixed by man.' Then they can lay out objectives on Iraq, the economy, the deficits etc. There's plenty of time between now and the next election but why wait so long? I think most Americans don't believe anything Bush or the GOP says on ANY issue so there's a massive power vacuum in Washington. Everyone perceives it and someone WILL stand up and grab it. They always do.

I think the main problem is very simple. We know we were lied to about this war and now we don't know what to do about it. Impeach Bush, the Congress and the media? Of course we don't trust the people who lied to us. Does anyone expect us to?