It’s a sign of the psychic costs of America’s ongoing epidemic of gun massacres that we have all learned to parse the casualties of the latest gun massacre within the frame of all the gun massacres that have gone before. People discussing what will become known as the Gilroy Garlic Festival massacre, which occurred on Sunday afternoon, took solace in the fact that only three victims were killed, until it was discovered that two of them were children, one just six years old. It’s as though, in some obscene way, there’s an implicit horror-score to be computed each time.

This gun massacre, however, occurred just after the death, on July 16th, of the retired Supreme Court Justice John Paul Stevens. There were many reasons to praise Justice Stevens, among them his genuinely judicious temperament, his capacity for reasoned argument, his respect for logic and evidence, and his allergy to dogmatic insistence of all kinds—all virtues that have been fading during the past decade of judicial polarization, and are now being aggressively eradicated under Trumpism. But perhaps his finest single legacy is his dissent—which may come to seem as distinguished as any in American history—to the genuinely deranged 2008 Supreme Court decision on gun laws in District of Columbia v. Heller. Concerning a near total ban on handguns in Washington, D.C., it was decided by a 5–4 vote, led by the late Justice Antonin Scalia, who wrote the majority opinion, which interpreted the Second Amendment to recognize a civilian’s right to keep a firearm unconnected to a “well regulated” militia. (Traditionally, significant decisions on the Supreme Court had to command significant majorities and otherwise lacked legitimacy. Brown v. Board of Education was a unanimous decision; Roe v. Wade decided on a 7–2 majority. Nowadays, precedents and, indeed, Presidents can be forced through with a one-vote majority, no matter the long-term cost to the legitimacy of the court. We have not yet meditated sufficiently, perhaps, on how aberrant that practice ought to be considered.)

Scalia’s reasoning in Heller hardly deserves the name. Neither the clear words nor the transparent intentions of the Constitution’s authors were taken up; instead, Scalia showed that you could, with effort, construe the words of the Second Amendment to mean something clearly different from what they had ever been understood to mean. His opinion involved suppositions about words and meanings as incredible to any meaningful philosophy of language as they are to any meaningful philosophy of law.

Stevens, in his dissent, wrote that an attempt to offer such a reading in the context of the Second Amendment is particularly risible, since no piece of American law could be more clearly contoured by a social purpose. As he writes, dryly demolishing the key argument in the majority opinion, “The Second Amendment was adopted to protect the right of the people of each of the several States to maintain a well-regulated militia. . . . Neither the text of the Amendment nor the arguments advanced by its proponents evidenced the slightest interest in limiting any legislature’s authority to regulate private civilian uses of firearms. Specifically, there is no indication that the Framers of the Amendment intended to enshrine the common-law right of self-defense in the Constitution.”

Stevens’s opinion is not just a persuasive legal argument but also a model of pragmatic reasoning. He patiently takes apart the claims of the majority, disassembling them piece by piece, like—well, like a man disassembling a weapon—and reasserts, past all reasonable counter-argument, that there is nothing in the Constitution to protect gun makers and gun killers from being disarmed in advance by their fellow-citizens. It was a logical argument in a losing cause, but it still stands, upright and unashamed, as the only logical argument that the case at hand could provoke.

Stevens’s dissent is particularly relevant now, because, once again, and with even more force, not only the urgency but the efficacy of gun control has become self-evident, and the case that gun control is constitutional needs to be made once again. The evidence all along has been that the presence of many guns correlates with the epidemic of gun massacres. New studies, including one published last year, by the Stanford University School of Medicine, and another published this month, in the journal of the American Academy of Pediatrics, reinforce what ought to be the unremarkable point that states with stronger gun laws see fewer children dying of gunshots. “If you put more regulations on firearms, it does make a difference,” Stephanie Chao, an assistant professor of surgery at Stanford, said. “It does end up saving children’s lives.” (It is no surprise that surgeons, who see children devastated by bullets, are often the originators of these studies.)

This spring, an appropriations bill passed the House which authorizes fifty million dollars in spending for the seemingly small cause of investigating the causes and cures of gun violence. This is a pursuit that, in a fully rational country, would need no pursuing—or would have been long pursued—but, given that all such research has been prohibited from receiving federal funding for more than twenty years, it’s a significant advance. As an editorial in Scientific American puts it, none of the recent smaller-scale studies “has had the power of large investigations that look at the effects of various kinds of interventions across the entire country and that involve tens of thousands of people. This is the kind of science that showed us the safety and health advantages of using seat belts, quitting smoking and reducing air pollution.”

So, when the Democratic candidates on the debate stage this week, in Detroit, are asked about gun massacres and gun control, as they will be, they need to do three things. First, they should endorse the House bill and even ask that the sums involved be increased. Second, they need to offer counsel against despair, even in the face of the staunch Republican resistance that will surely rise in the Senate regarding this mild investigative initiative. The reason that we know as much as we do about gun violence is that state-by-state legislation that has already been passed is saving lives. That smaller-scale legislation isn’t enough; the gun for this latest massacre in California, which has strict laws, was bought in Nevada, which does not. But we ought to promote making guns harder to obtain in as many towns, cities, and states as we can, even if we cannot yet entirely nationalize gun sanity. It makes a difference.

And the candidates should not be afraid of taking “radical” positions. One lesson—however paradoxically it must be learned from the astounding reversal of long-settled law in Heller, and, more broadly, through the unprecedented insistence, over the past thirty or so years, on putting military-style weapons into private hands—is that ideas that were once fringe can be made central, if they are put forward with enough passion and purpose. Incremental change will be a necessary fact of the path to gun sanity. You start somewhere and go farther. We are told over and over that laws banning assault weapons are impossible to pass because there are already so many of the weapons available—and what is an assault weapon, anyway? (That’s actually easy to answer: it’s one designed to imitate military weapons that are designed to kill many people quickly.)

But there is no reason to let difficulty be the enemy of the determination. We’ve heard long enough about “background checks” and gun-show loopholes. It’s time for politicians to speak up for an outright and permanent ban on assault weapons, and subsequent bans on the handguns that are the cause of many more deaths. Every study and every survey shows that the overwhelming body of the American people are in favor of gun sanity. The example of Justice Stevens’s life involves the power of rational argument to endure in all its integrity, even in the face of obvious madness. The candidates should remember that, as Stevens showed, you can argue rationally for a passionate purpose, and passionately for a rational one. Doing that is exactly why we have politics.