Back in my primitive college days, students would sometimes argue about politics and current affairs on the Kirkland House email list serve.

When the United States invaded Iraq, I made the argument — which I regret both because it was totally wrong and also because several students told me at the time that it persuaded them — that the progressive hothouse environment of the Harvard campus was leading people to dramatically underrate George W. Bush’s odds of success. At the end of the day, I said, Bush had access to all kinds of intelligence and military professionals. And while he obviously might shade the truth or engage in misleading rhetoric (as all politicians do), it fundamentally made no sense for him to allege that Iraq had an advanced WMD program unless he had a very high degree of confidence that they did, in fact, have an advanced WMD program. The opposite would, after all, result in a huge political embarrassment with obvious blowback.

More broadly, I argued that the whole i…