Do you feel that? That’s your sense of moral outrage dissipating.

It may still feel raw and vivid in the wake of Friday’s bloodbath in Connecticut. But if other recent massacres are anything to go by, our collective indignation has a half-life—and it isn’t long. The tender ages of the victims at Sandy Hook made the tragedy feel exceptional, and on television and Twitter, and at kitchen tables around the country, many of us expressed an urgent sense, over the past forty-eight hours, that something should be done. Even President Obama suggested that “meaningful action” is in order, though he didn’t elaborate on what that might entail, and notably absent from his remarks was the single syllable that might explain how one disturbed young man could walk into an elementary school and end twenty-six lives in a matter of minutes: “gun.”

One irony of the pernicious taboo on “politicizing” a tragedy is that in some especially thorny areas of policy—like, for instance, gun control—it is only a tragedy that can summon the political momentum for change. The original Gun Control Act passed in October 1968, following the demoralizing assassinations of Bobby Kennedy and Martin Luther King, Jr. The Brady Act owes its existence to the unsuccessful attempt on the life of Ronald Reagan.

But by 2011, when Gabrielle Giffords narrowly survived a bullet in the head, the dynamic of the debate had changed. “After the Giffords shooting, I thought something would happen with gun control,” a recently retired official from the Bureau of Alcohol Tobacco and Firearms told me last summer. But nothing did. “Apparently, a member of Congress doesn’t count,” he said. “So now I’m wondering, what exactly does it take? Another Presidential assassination?”

What does it take? If a congresswoman in a coma isn’t sufficient grounds to reëvaluate the role that firearms play in our national life, is a schoolhouse full of dead children? I desperately want to believe that it is, and yet I’m not sure that I do. By this time next week, most of the people who are, today, signing petitions and demanding gun control will have moved on to other things. If you want to understand why the gun debate can occasionally feel rigged, this is the answer: the issue is characterized by a conspicuous asymmetry of fervor. The N.R.A. has only four million members—a number that is probably dwarfed by the segment of the U.S. population that feels uneasy about the unbridled proliferation of firearms. But the pro-gun constituency is ardent and organized, while the gun control crowd is diffuse and easily distracted. In the 2012 election cycle, N.R.A. spending on lobbying outranked spending by gun control groups by a factor of ten to one.

What that means in practice is that in the aftermath of contemporary gun tragedies, we don’t see new gun legislation. What we do see is a spike in gun sales. After the shooting last summer in Aurora, Colorado, gun sales went up. After the Giffords shooting, there was a surge in purchases of the very Glock semiautomatic that wounded her. Certainly, the firearm industry and lobby will confront some bad P.R. in the coming weeks, but they can likely find succor in an uptick in business. Following the Newtown shooting, Larry Pratt, the Executive Director of Gun Owners for America, suggested that these massacres might be avoided in the future, if only more teachers were armed.

As Pratt’s sentiment should make clear, the United States has slipped its moorings and drifted into a realm of profound national lunacy. Ponder, for a second, the fact that I cannot walk into a C.V.S. today and purchase half-a-dozen packages of Sudafed, but I can walk into a gun dealership and purchase a .50 caliber rifle of the sort that U.S. snipers use in Afghanistan. In fact, I can buy six or ten—there is no limit imposed by law. Should the gun dealer think it fishy that I might want to acquire a weapon capable of downing a small aircraft (much less six of those weapons) he may report the purchase to the A.T.F. But in most states, he’s not required to.

To some readers, that may seem eminently reasonable. But what about this? The state of Indiana recently enacted a law that enshrines an enhanced version of the “Castle Doctrine,” that quintessentially American notion that you are within your rights to shoot and kill someone who is trespassing on your property. The Indiana statute, which was backed by the N.R.A. over strenuous objections from law enforcement, explicitly extends this precept to intruders who are “public servants,” but who you believe have no appropriate basis for entering the premises. In other words: under certain circumstances, it is now hypothetically legal under Indiana state law for you to shoot a cop.

The saddest aspect of Obama’s failure to address the deadly and dysfunctional role that guns play in American life is that he knows better. As David Remnick detailed on Friday, both in his Chicago years and as a candidate in 2008, Obama expressed support for greater gun control. After his election four years ago, gun sales shot up in anticipation of forceful new regulation. But the regulation never arrived. When Attorney General Eric Holder suggested in February 2009 that the Administration might seek to reinstate the assault-weapons ban, he was reportedly chastised by Rahm Emanuel, and told to drop the subject. That year, the Brady Campaign to Prevent Gun Violence gave the new President an “F” for his gun record. But you’d be underestimating the gun lobby if you thought they’d take yes for an answer. The N.R.A. relies, for its existence, on the appearance of persecution—or, in the absence of any actual persecution, on the illusion of it. So in a bit of public relations jiu-jitsu that was nothing short of inspired, the gun lobby argued, as 2012 approached, that while Obama may have totally capitulated to their agenda during his first term, he was merely biding his time. Surely, if he was reëlected, the Great Confiscation would begin. Sales soared (are you noticing a pattern?) as frightened gun owners stockpiled weapons that might soon become illegal. Sen. Mark Pryor, a Democrat from Arkansas, joked that the President had become “his own stimulus plan for the gun industry.”

Part of the reason that alarmism has been such a successful tactic for the N.R.A. is that gun control advocates have a lamentable habit of playing, unwittingly, into their talking points. As the public reacted to the events at Sandy Hook on Friday, many people took to the airwaves and the Internet to make a strident case for greater gun control. But they often betrayed a certain prudish illiteracy when it came to the basic features of the firearms and laws that they were talking about. There were calls to ban “automatic” weapons, though fully automatic weapons are already illegal, and the Newtown shooter used semiautomatics. There were also calls to reinstate the assault-weapons ban, a notion that White House spokesman Jay Carney said yesterday, remains “a commitment” for the President. Such a law would probably cover the type of Bushmaster M4 assault rifle that the shooter used on Friday. But even when it was originally passed in 1994, the ban was a highly compromised piece of legislation. It only covered sales after the effective date of the law, so any assault weapon already in private possession was effectively grandfathered in. And, of course, there was a spike in gun sales before the enactment of the law.