1. John McCain supported the surge before it was cool.
2. The surge caused a reduction in violence.
3. This implies that McCain has good foreign policy judgment.
The accuracy, importance and relevance of the first and third points have been questioned extensively, of course. The second one is generally taken as an article of faith, and granted even by Obama backers. But is it true? Is the surge mainly responsible for the decline in violence, or were Moqtada al-Sadr's semi-retirement, the Anbard awakening, and the ethnic cleansing in Baghdad bigger factors? Was the surge even a tactical success?
Ezra and I doubted it. But don't take our word for it: we asked basically every think tank type who writes about Iraq for their thoughts, and they all agree it's complicated. The results are here. Unsurprisingly, Michael O'Hanlon and John Nagl represent the right flank, with Juan Cole and Larry Korb on the left and Colin Kahl, Tom Ricks, etc. somewhere in between.