After the Columbine High School shooting in 1999, I wrote a book that asked why America had never developed much of a gun control movement. To answer the question, I looked at similar life-and-death issues around which vigorous movements had arisen and found three common elements: funding from wealthy patrons, incremental strategies that delivered momentum-building victories and maternal calls to action.
It rarely makes sense to draw big conclusions or make public policy on the basis of anecdotes. But the plural of "anecdote" is data, and sometimes one-off events are useful in crystallizing lessons to guide policymakers and inform the public. So it was with the Pittsburgh-area rampage this week in which a teenager bearing two kitchen knives is accused of injuring 21 high school classmates and a security guard -- but none of them were killed. It's hard to imagine an anecdote that better illustrates what decades of data show: that for purposes of life and death, the weapon matters.