Rich Lowry writes that it's the mindset on college campuses:

The left's new faith, now that socialism has died, is pessimism. I'm struck by this when I'm on college campuses. I want to say to these kids (and professors), “OK, you think Bush's foreign policy is a disaster, but what do you believe, what's the alternative, what's your vision?” There is none. These people believe in nothing. They aren't even soft-headed idealists anymore because Bush's idealistic rhetoric has prompted them to reject idealism. All they have is a smug faith in American failure, that whatever we do--literally whatever we do: whether its militaristic or altruistic or something in between--is wrong and doomed to fail.