Trying to understand this determination to stay the course no matter how unlikely the prospect of success, it might help to turn to a quip from one expert on Afghanistan, Rory Stewart, who heads the Carr Center for Human Rights Policy at Harvard and has been consulted by several members of the Obama administration on what to do there. He has testified before Congress on Afghan policies, but wonders how much affect he's having.
As quoted in Matthew Yglesias' blog, Mr. Stewart says, "It's like they're coming in and saying to you, 'I'm going to drive my car off a cliff. Should I or should I not wear a seat belt?' And you say, 'I don't think you should drive your car off the cliff.' And they say, 'No, no, that bit's already been decided - the question is whether to wear a seat belt.' And you say, 'Well, you might as well wear a seat belt.' And then they say, 'We've consulted with policy expert Rory Stewart and he says …'"