Apr. 19

　　The president of Virginia Tech, Charles Steger, should resign. But not because of the school's rather slow realization Monday morning that a demented murderer was on campus. Mass shootings are infinitesimally rare. As the Department of Justice points out here, in 2004 less than 0.1% of all homicides involved five or more victims. The rate of homicides involving more than two victims has been under 1% since at least the mid-'70s. In other words, statistically speaking, the cops who arrived at Ambler Johnston on Monday morning to find two dead bodies had every reason to believe the killer was finished.

　　But assuming that an unknown murderer won't leave the scene and keep shooting people is different from assuming that a person who has long been identified as a threat, as Cho had, won't hurt someone. The fateful decisions that cost the lives of 30 more people at Virginia Tech weren't made on Monday morning; they were made in the previous 18 months.

　　校长应辞职

　　弗吉尼亚理工大学校长查尔斯·斯蒂格应该辞职，不是因为星期一上午学校很迟才意识到校园里有一名疯狂的杀手。大规模的枪击事件是极为罕见的。正如司法部的报告所显示的，2004年所有杀人案中死亡5人或5人以上的不到0.1%。至少从70年代中期以来杀人案中死亡2人以上的一直在1%以下。换句话说，根据数据，当警察在星期一早晨到达安伯勒·约翰斯顿发现两具尸体时，完全有理由相信凶手已经干完了。

　　但是，假设一个不知名的杀手杀人后没有离开现场并继续向人们开枪射击和假设一个像赵那样的、长期以来被认定是危险人物的人不会去伤害别人，那结果就不一样了。导致30多人死于弗吉尼亚理工大学的致命决定并不是在星期一上午做出的，而是用了过去18个月才决定的。