One person who (unsuccessfully) threatened the lives of his fellow airline passengers ten-and-a-half years ago has changed air travel for every single passenger on every U.S. flight in all the time since then. We responded (and over-responded) to that episode with a “this won’t happen again” determination, like other countries’ response to mass shootings. It is hard to know what kind of mass killing with guns would evoke a similar determination in America. The murder of six people including a federal judge and near-killing of a Congresswoman last year obviously didn’t do it. Nor, in all probability, will these latest two multi-death shootings. In their official statements of condolence yesterday, both Barack Obama and Mitt Romney replicated their achievement after the Aurora murders: Neither used the word “gun.