Matt, in a post about how Kevin Drum echoes his thinking on Iraq, pens a terrific explanation of where I've landed in recent months:
That said, I've sort of been shifting away from the "had no chance of working even if it had been competently executed" view in favor of a more sophisticated one. Here's how I would put it. In Iceland, they often need to close a road or two to traffic because it's too dangerous. That doesn't mean it would be literally impossible to drive safely across it. If you drove perfectly, you could probably make it. But the road is closed precisely because it's so rare for someone to drive perfectly in difficult conditions. A dangerous undertaking that can only be done successfully if you never make a mistake, is something you ought to avoid doing. After all, it's not as if the United States won the second world war, or the civil war, because our strategy was flawlessly executed. There were plenty of mistakes and errors along the way. There are always mistakes and errors in such a large undertaking as a war. Which is precisely why there should be a strong presumption against undertaking wars of choice. It's a distinctively liberal error to think "massive, flawlessly executed government-sponsored venture" is a real option to be put aside "don't do it" and "do it but make some mistakes." Mistakes, when made, should of course be criticized, but on side level some mistakes are inevitable. If your plan depends on the absence of errors, then you've got a bad plan.
This is one of those long-time, historically recurring mistakes liberals make. From the Kennedy Brothers' deification of CIA operatives, which led to the Bay of Pigs, to the liberal hawk's reliance on Kenneth Pollack's smiley, heroic vision of an Iraq occupation, we get this wrong a lot. Indeed, the only time I can think of it working, or even coming close, is in Kosovo, where our military strategy was idiotic and took us months longer than it should have, but our mistakes were on the side of caution and thus our own ranks remained blissfully unthinned (the Kosovars experienced no such luck). But in Iraq, our mistakes were all strikes against prudence, and so the casualty count and emotional immediacy of the many missteps and strategic failures proved much higher.