Every time an armed madman fills a school or office or shopping center with bleeding bodies, the question is asked: Why does the National Rifle Association oppose restrictions on semiautomatic weapons and high-capacity ammunition clips? As a non-hunter who's never owned a gun, I used to puzzle over this myself, until I decided some years ago to pay a visit to the local gun club. I told the very friendly group of guys I found there that I understood the need for a handgun or rifle to protect yourself or to hunt. But why insist on legal access to weapons and magazines created for the military and police, with the capacity to massacre dozens of people in seconds? They smiled at my naïveté. One day, they explained, we may need weapons with serious firepower to fight the military and the police, in an armed rebellion against the government.

This is not a fringe view, held only by shaved-head militiamen in camouflage uniforms. Though not often discussed around hostile audiences, the belief in the "right of revolution" is a fundamental tenet shared by tens of millions of gun enthusiasts, and is at the heart of the NRA's determined — and successful — fight against gun-control laws. As actor and NRA activist Chuck Norris puts it, "If the government decides to become a tyrannical government, our guns are to protect us against that. And that's really what the Second Amendment is all about." In response to the latest bloodbath, gun-control advocates will once again demand limits on how much killing power citizens can purchase. But it’s "the right of revolution" that will stand in the way.