Another mass shooting, another round of liberal venom hurled at people who oppose further gun control measures. In the wake of the slaughter in San Bernardino, the charges were particularly shrill. “Dear ‘thoughts and prayers’ people: Please shut up and slink away. You are part of the problem, and everybody knows it,” said one liberal Washington Post columnist, in a representative tweet.Most gun control advocates know that the push for federal gun laws is futile. Public support for gun rights is near historical highs, the structure of the U.S. Senate favors pro-gun forces, and—as many observers pointed out at the time—if the tragedy at Sandy Hook couldn’t get gun legislation through the Congress, nothing can, at least for the foreseeable future. But liberal decision to make the San Bernardino massacre a story about gun control is more than futile—it is fundamentally disconnected from the role the Second Amendment has played in American political thought, and therefore might be even less effective than past efforts.There is of course wide disagreement about the proper scope of the Second Amendment in the 21st century. But there is no doubt that the chief historical purpose was to ensure that the civilian population had a means of protecting its political liberty at home. Since the founding, the idea that the citizenry should be able to provide for the common defense against “foreign invasions” and “domestic insurrections” (to use Supreme Court Joseph Story’s words from his 1833 commentaries) has provided the foundation of Americans’ enduring support for gun rights. Today, almost two-thirds of Americans see an armed citizenry as a protection against tyranny. The idea of citizens safeguarding their freedom with their own arms is hardwired into America’s Jacksonian character.That’s where the San Bernardino shooting comes in. There now seems to be very little doubt remaining that the mass murder in San Bernardino was an ISIS-inspired jihadist attack. This makes it fundamentally different from the massacres at Aurora and Newtown. Not any more tragic, not any more evil—but categorically different, from a political standpoint. It appears that this was not a random act of violence committed by a psychopath, but a carefully orchestrated attack by individuals who had pledged allegiance to a totalitarian political movement that is at war with the United States. As Ross Douthat has suggested, this kind of political violence, inspired by a global jihadi network, is so frightening in part because it “challenges the government’s monopoly on organized force.”The post-San Bernardino debate is different from previous fights over gun, crime, and self-defense. According to the Supreme Court, the Second Amendment does protect a right to self-defense, but this is tangential to its historical role in American political thought: not as a pragmatic tool for hunting and warding off criminals, but as a political tool to safeguard self-government in America. The attack at San Bernardino cuts to the core of what the Second Amendment—in the minds of many Americans—is all about. Liberals who believe that jihadist attacks in the homeland will persuade Americans to disarm are very likely deluding themselves.