So ... jihad? Workplace revenge, like that perpetrated last year at a FedEx warehouse in Kennesaw? We don't know, but I suspect it doesn't matter much to the friends and families of their 14 dead victims. You can drive yourself crazy trying to make sense of the senseless.
But to give us a sense of perspective, let's look at some data:
Since 1994, the number of murders and non-negligent manslaughter committed with firearms has been cut almost in half. The overall murder rate has been cut by more than half. And no, the decline is not caused by armed civilians intervening to prevent crime. The number of justifiable homicides by a civilian with a firearm was an almost negligible 316 back in 1994, and it had dropped to 229 in 2014.
So in a general sense, we're making real progress. That's important to keep in mind. We're clearly succeeding in reducing what might be called "discriminate violence," the typical murders in which victim and perpetrator have some relationship. What seems to be increasing, although we lack FBI data in this case, is "indiscriminate violence," violence in which the angry and disgruntled and disturbed among us gain legal access to powerful firearms and inflict blind carnage. And in many ways that's more frightening and unsettling.
So what do we do?
I've already proposed to ban the sale of ammunition to anyone who cannot demonstrate that they have passed a background check and taken a gun-safety course. Those are minimal steps that every responsible citizen who wants ammunition for hunting, sport shooting and self-defense would have no problem completing, without impingement on their Second Amendment rights. They are also steps that would deter the delusional and criminal. It would by no means solve the problem of gun violence, but it would save lives.
I would also ban the sale, commercial or private, of semiautomatic military-style assault weapons with a capacity of more than 10 rounds, and require the registration of those weapons already in private hands just as fully automatic versions are required to be registered.
I would ban the civilian sale of body armor and other paramilitary equipment that feeds the fantasies of the delusional and those with terrorist ambitions. And I would attempt to delegitimize and deglamorize the notion that the Second Amendment enshrines the gun as some legitimate tool of political expression, because it does not. No court has ever embraced that reading, and no politician should endorse it even tacitly. The theory of the gun as a means of forcing political change is the theory of the terrorist.
In a more rational political environment, of course, none of those steps would be controversial. They respect and protect the gun rights of responsible law-abiding Americans while protecting public safety, but because they would also inflame the fears of the paranoid, they cannot even be seriously considered. It's a bizarre situation, but again, we've grown so accustomed to the bizarre that we no longer see it as such.