This scenario almost never happens. The logic is nonsense, the odds of a perfectly timed counter-killer getting the drop on the evil killer unlikely. And even when such a situation does happen, as in the Tucson shooting of 2011, the armed citizen who jumps into the melee can pose a mortal threat to others. In Tucson, an innocent person came within seconds of getting shot by an armed bystander who wasn’t sure whom to shoot.

Most gun-free zones, like the theater in Lafayette, La., are not gun-free at all. They have no metal detectors or screening — that would cost too much, the theater owners claim. Gun-free is a suggestion, and therefore a misnomer. Eventually, the more prosperous theaters in better communities will pay for metal detectors, further setting apart the two Americas in our age of mass shootings.

The Mall of America — more than 500 stores in four miles of retail space, drawing 40 million annual visitors to a climate-controlled part of Minnesota — is trying to be a gun-free zone. “Guns are banned on these premises” is the mall’s official policy.

If the mall took up Rick Perry’s suggestion, shoppers could roam among the chain stores packing heat, ready for a shootout. The owners of that vast operation, similar to those who stage concerts and pro sports, think otherwise. The mall has a security force of more than a hundred people. Yeah — I hear the joke about the feckless mall cops. But the Mall of America trusts them more than well-armed shoppers to protect people, as they should.

Surprising though it may seem, gun ownership is declining over all in the United States. We are still awash with weapons — nearly a third of all American households have an adult with a gun. But that’s down from nearly half of all households in 1973.

What we’re moving toward, then, are regions that are safer than others, and public spaces that are safer than others, led by private enterprise, shunning the gun crazies who want everyone armed. The new reality comes with the inconvenience and hassle of screening and pat-downs similar to the routines at airports — enforced gun-free zones, not mere suggestions.

As a way to make everyday life seem less frightening, the new reality is absurd. But that’s the cost, apparently, of an extreme interpretation of a constitutional amendment designed to fend off British tyranny, a freedom that has become a tyranny in itself.