"We captured a bunch of people. Some are harmless unfortunate bystanders. Some are dangerous people who are nevertheless not immune to handcuffs. Still, we'd better lock them up in harsh conditions without trial just in case."

"Iraq probably has no nuclear weapons and no means to deliver one, but we'd better invade the country just in case. We don't want to be wrong and end up with a mushroom cloud over Manhattan."

>Shortly after September 11th 2001, I thought to myself, and now someone will turn up minor intelligence warnings of something-or-other, and then the hindsight will begin. Yes, I'm sure they had some minor warnings of an al Qaeda plot, but they probably also had minor warnings of mafia activity, nuclear material for sale, and an invasion from Mars.

>Because we don't see the cost of a general policy, we learn overly specific lessons. After September 11th, the FAA prohibited box-cutters on airplanes—as if the problem had been the failure to take this particular "obvious" precaution. We don't learn the general lesson: the cost of effective caution is very high because you must attend to problems that are not as obvious now as past problems seem in hindsight.