Security ... think about it!
While I agree that arguing that terrorism is statistically harmless isn't going to win any converts, I still think it's an important point to make. We routinely overestimate rare risks and underestimate common risks, and the more we recognize that cognitive bias, the better chance we have for overcoming it. And Kevin illustrates another cognitive bias: we fear risks deliberately perpetrated by other people more than we do risks that occur by accident. And while we fear the unknown -- the "reminder that al-Qaeda is still out there and still eager to expand its reach and kill thousands if we ever decide to let our guard down a little bit" -- more than the familiar, the reality is that automobiles will kill over 3,000 people this month, next month, and every month from now until the foreseeable future, irrespective of whether we let our guard down or not. There simply isn't any reasonable scenario by which terrorism even approaches that death toll.