One of my commenters asks what I got wrong on the Iraq war. I've posted on this before, but I suppose it's worth saying again what I've learned from the experience.
1) I lost my normal scepticism about the government's ability to make things better. This is not a "I trusted Bush too much"; perhaps the Bush administration is really the reason that everything went wrong, but I am not in a position to evaluate that. I simply forgot to be skeptical that we could build a functioning nation in Iraq. The military performed beautifully--at its core task, which is killing people and seizing military targets. I therefore assumed that we would also be able to build a functioning government and economy. This can be done by people with a lot of tanks and high explosives, but not in any way that I would approve of.
2) I paid too little attention to how the Iraqis would feel. Despite my core belief that I live in the best country in the entire world, I'm basically a cosmopolitan. I should have realized that the Iraqis would find it humiliating to be conquered by an outside power, even one that was (as we are) one of the best-meaning occupiers in human history.
3) I overestimated my ability to interpret Saddam's behavior. I genuinely believed that he had WMD--the main reason I favored invasion--because he was acting exactly like I would if I'd had WMD. I failed to adequately consider that not being a brutal dictator in a chronically unstable region, I probably had limited insight into his thought process.
4) I forgot that institutions matter. The experience of Eastern Europe after the fall of the Iron Curtain revolutionized our thinking about markets. We used to think that they were the natural occupant of any space left free by the government. Now it turns out that they are supported by a dense network of custom and law that is largely invisible to us for the same reason that you can't tell someone how to ride a bike. I knew this, or should have--yet I expected that once we smashed Saddam, democracy and freer markets would naturally fill the vacuum.
5) I failed to consider who would come after Saddam. The corollary to that is that I didn't look hard enough at the possible succession. I imagine that, like the US government, I thought that the exiles could go back and take over; I had more excuse than they did, but not that much. Most exiles aren't De Gaulle.
6) I paid too much attention to the French. While in general, "Whatever France is doing, don't do that" is very good policy advice, it is not actually true that everything the French oppose is therefore a good idea.
7) I fell prey to the notion that we had to do something about Islamic terrorism. This was something. In retrospect, there were many better somethings to do. For example, we could have invaded France.
I'm sure there were other errors I made, but those are the ones that I can identify five years later.
The biggest thing I've learned is simple humility. Almost any set of facts can tell two stories; I will never again be so sure that my story is right.