September 11, 2001 was a tragedy. Many (though not all) U.S. foreign policy decisions following the attacks were also tragedies. The decision to allow the use of "enhanced interrogation" (aka, torture) is one such example. Today, whenever I think about September 11, my first thought is not that my country was profoundly wronged but that we did something dreadful to ourselves: we sold off part of our national soul for a little security. It is a difficult causal question, but I am convinced that we would not have struck such a bargain with the devil had it not been for the attacks.
Anyway, reflecting on our endorsement of torture following the events of September 11, 2001 reminded me of an excellent Daily Show interview, wherein Jon Stewart argues with Marc Thiessen about the causal efficacy of torture. You can watch the extended interview (in three parts) here: Part 1, Part 2, and Part 3.
One of the (many) things I like about the interview is that it shows how seemingly arcane questions of only philosophical interest -- like whether or not counterfactuals are backtracking -- apply to meaningful policy debates. Another thing I like is that depending on how the causal question is settled, the moral question might turn out to be irrelevant. That is, if torture is ineffective at producing actionable intelligence (and it probably is), then it doesn't matter whether there are apparently clever rationalizations of torture.