Slate's What I got Wrong series on the five-year anniversary of the Iraq War, and similar efforts from other media outlets, have triggered a fair amount of irritation, especially among those who opposed it. Says Timothy Noah:

Why should you waste your time, at this late date, ingesting the opinions of people who were wrong about Iraq? Wouldn't you benefit more from considering the views of people who were right? Five years after this terrible war began, it remains true that respectable mainstream discussion about its lessons is nearly exclusively confined to people who supported the war, even though that same mainstream acknowledges, for the most part, that the war was a mistake. That's true of Slate's symposium, and it was true of a similar symposium that appeared March 16 on the New York Times' op-ed pages. The people who opposed U.S. entry into the Iraq war, it would appear, are insufficiently "serious" to explain why they were right.

I heard a fair amount of that this weekend. But I think it's seriously misguided.

The universe being a complicated place, you can usually tell multiple stories from the same pieces of evidence. We learn by gambling on what we think the best answer is, and seeing how it turns out. Most of us know that we have learned more about the world, and ourselves, from failing than from success. Success can be accidental; failure is definite. Failure tells us exactly what doesn't work.

Failure tells us more than success because success is usually a matter of a whole system. And as development economists have proven over and over and over again, those complex webs of interactions are impossible to tease apart into one or two concrete actions. Things can fail, on the other hand, at a single point. And even when they fail in multiple ways, those ways are usually more obvious than the emergent interactions that produced a success.

At the decision point where we decided to go into Iraq, there were two hypotheses we could have tested:

1) Something terrible will happen if we leave Saddam in power
2) We can depose Saddam and leave the world a better place

We chose to test hypothesis number two. So far, it looks like a dud.

Since it failed, the more interesting question is not what did you get right, but what did you get wrong. The people who were right can (and will) rewrite their memories of what they believed to show themselves in the most attractive light; they will come to honestly believe that they were more prescient than they were. This is not some attack on people who were against the war: I was wrong, they were right. But everyone does this with almost everything--indeed, not rewriting memory in this way is so rare that there's a clinical term for it. We call it "major depression". They will also quite possibly simply be wrong about how they got it right; correct analysis often operates at a subconscious as well as a conscious level.

The people who failed will also do this. But unlike the people who were right, there is a central fact stopping them from flattering themselves too much: things are blowing up in Iraq and people are dying. Thus they will have to look for some coherent explanation.

To be sure, many of those explanations are wan and self-serving--"I trusted too much." But others of them aren't. And the honest ones are vastly more interesting than listening to a parade of people say "Well, obviously, I'm a genius, and also, not mean."