There are two factors common to mass shootings in the United States, and a "vector," as the Atlantic's Jeffrey Goldberg says, that links the two.

One is easy access to firearms capable of killing lots of people quickly. The second is the perpetrator's having a history with mental illness.

On the first, significant minorities of all guns purchased or obtained in the United States are done without the benefit of an instant background check. This is not a loophole; it is a circus ring. The background checks are relatively limited in scope, as is normal. This is relevant because, for reasons of law and technologies, it is hard to scour the most relevant records quickly.

On the second, the alleged gun-wielding murderers who shot up Columbine, Aurora, and Ft Hood, among many others, have all been discovered to have had in retrospect clear signs of mental illness. In some cases, privacy laws preventing doctors from disclosing this to employers and others. In others, the level of mental illness or distress was relatively benign; none of us would want our own human difficulties disclosed or added to a database as part of some sort of mass surveillance effort aimed at tracking everyone who has seen a psychiatrist.

So: Is it easier to tighten access to guns or broaden access to mental health records? Each may conflict with a value — the second amendment in one case and privacy in the next — but which value is worth sacrificing to some extent in order to move forward?

The answer to me is fairly obvious: Everyone who wants to have access to a gun can do so provided they register their weapon and get state-sanctioned training. The types of guns that people can carry on their persons ought to be limited to those made legitimately for self-defense. The gun show loophole should be closed; with the exception of family-to-family transactions or old weapons given as gifts, every sale or exchange of a weapon must be registered. The instant background check will be replaced for new gun owners with a state-approved training course that includes a more extensive background check. (Each state course would have to meet basic federal guidelines but could differ in the particulars.)

A tax on gun purchases would fund this new system. People would have access to guns; they could not be denied access to guns on the basis of anything other than mental fitness, failing their training, or having a criminal record. (Juvenile records count.) The relationship between the gun owner and the government would change from a conflict model born in the origin myth of our founding — that King George and his minions were out to gets us — to a model founded upon the value of cooperation, where self-defense and safety were balanced. Gun manufacturers and ammunition makers would have to change their business practices here, too.

What to do about mental health? More money for mental health programs? Maybe. Better training for teachers to recognize troubled students? Yes, but in 999 out of 1,000 cases, the symptoms that might indicate a propensity to violence probably just reflects a propensity to do drugs. Better access to mental health records? Yes, but what's the right balance here? Should psychiatrists be forced to report every kid who seems oppositionally defiant? If a neighbor calls the police after hearing an argument next door, do the police have to treat the participants as potential mass shooters? That type of response would force untrained police officers to act as mental health screeners, very much to me the exemplification of modern totalitarianism.

American politicians need to get off their butts. So far, most, including the president, have abdicated a moral responsibility to talk frankly about guns and rights, ironically, they say, because the issue is "complicated." Goddamn right it's complicated. That's why we ought to talk about. Democrats still adhere to the fear that if they mention common-sense gun rules, their party will lose the backing forever of gun owners and those who see gun ownership as a stand-in for checking government power. For the most part, though, that coalition isn't the Democratic Party's coalition, and it becomes less so with every election.

The gun rights lobby could lead the charge here, but they won't, because they're afraid they'd lose the chance to demagogue politicians who rise up against them. The NRA's opponents are as central to the NRA's successes as anything else.

So: Ball's in your court, Mr. President.