There is a deranged person with a gun at the door of your kid's classroom. In that instant, do you want your kid's teacher to be armed? Of course you do.
This is the image presented by the NRA's recently announced "response" to the Newtown shooting and other shootings. And in that instance, any sane person would want the defenseless teacher armed. Not only would we want the teacher to have a gun, but we'd prefer that it be a really powerful assault weapon. Frankly, we'd probably like it even more if the teacher were surrounded by a few dozen really pissed-off Navy SEALs.
But the fallacy of this image is that it ignores the other 99.999999 percent of the time, when there is no deranged potential killer at the door. Is that gun locked up in the normal course of life? Does the teacher ever forget to lock it? Do these naturally curious kids ever observe where the teacher keeps the key to the gun cabinet? Does a curious kid ever decide to take a look at this intriguing forbidden fruit? And how many tens of millions of person-years are kids in school while they are at risk of one of these things happening? What happens next if they act on their natural curiosity?
We can take this same calculus and apply it to our home. A deranged person (or a garden-variety burglar, for that matter) intrudes upon our home while we are home. In that instance, what sane homeowner would not want to be fully armed? It is easy to visualize the moment in which we would feel at risk and vulnerable if we were unarmed in that instant. The thought of being defenseless in such an imagined moment can be terrifying.
The problem with basing social policy, or even the personal decision to arm oneself, on such extremely unlikely hypotheticals is that if we focus only upon them, then we can make very bad and statistically irrational decisions that increase rather than decrease the risk to ourselves and our loved ones.
The calculus is a lot like our poor assessment of risk in other areas. Who has not stuck their toe in the ocean without giving a thought to sharks in the water -- this despite the fact that there are only a handful of shark attacks on humans worldwide each year? Why do we focus on the image of a shark in the water? Because the image of a shark's teeth tearing our defenseless flesh is so terrifying that we do not consider that our risk of dying in a car accident within a few miles of home is tens of thousands of times more likely. So we regularly drive without giving this a single thought. And many fear commercial airline flights (which are far safer per mile than is routine driving) because we feel that the outcome of a flight is out of our control. As a result, our fears in many areas are grossly disproportionate to objective risk.
That image of a home intruder is terrifying. Many people arm themselves in response to it, ignoring clear data that weapons at home put the armed homeowner and his family at far greater risk of injury from a momentarily furious spouse or a curious child. But spouses and children do not conjure up the same fearful images as does the armed intruder, so it is easy to ignore the greater risks associated with greater access to firearms.
While the relative risks of such incidents are clearly misperceived, the images they create are genuinely terrifying and are embedded in our collective consciousness. If advocates of greater gun control want to make any significant progress, they have to figure out how to allay such fears or they will continue to lose the larger argument.