Michaela Granello, left, 19, takes a photo of the growing memorial in front of the Jack Evans Police Headquarters building on July 11 in Dallas. (Stewart F. House/Getty Images)

THE SOLUTION to a bad guy with a gun, it is often said, is a good guy with a gun. Yet according to Dallas Mayor Mike Rawlings (D), there were 20 to 30 good guys openly carrying guns among the protesters whom Dallas police were supervising last Thursday night, when Micah Xavier Johnson began picking off officers. “In the middle of a firefight,” the mayor said Sunday, “it’s hard to pick out the good guys and the bad guys.”

In fact, the presence of so many guns could have made Thursday’s massacre worse. Officers did not know where the shooting was coming from, how many people were involved or what kinds of weapons they were facing. Innocent protesters publicly toting guns became immediate suspects. Their presence fed the confusion and amped up the danger.

Yes, guns can be properly and effectively used in self-defense. But saturating the nation with firearms also primes the country for deadly violence, making many situations more likely to end in death. Potential suicides are more likely to succeed. Deranged and angry people, such as Johnson, can murder trained law enforcement officers from a distance. Curious children accidentally shoot themselves, their friends or their parents. Domestic abusers kill family members before tempers cool or authorities arrive. Police officers see or fear guns in the cars they pull over, and their adrenaline starts pumping.

Debate about gun laws spikes after mass shootings because their carnage reminds us that guns are uniquely and efficiently deadly, and pitifully under-regulated relative to the risks they pose. Yet gun violence in the United States is also unacceptably mundane, taking one or two lives at a time, all the time, with little fanfare and few headlines — just an ambulance carrying away the corpse of another battered wife, another child, another mentally ill person who felt she had no other option. Some of these deaths would happen even if the nation had sensible gun laws. Many would not.

Partially because of gun advocates’ pressure on research organizations, public health experts have relatively little data on gun violence. But the research that exists increasingly shows there are effective measures that reduce gun deaths without materially infringing on law-abiding people’s liberty: deny firearms to domestic abusers, for example; perform serious background checks on would-be gun buyers; require that gun owners obtain a license. Such measures would not stop every person bent on doing harm. They might not have prevented the Dallas massacre. But by making guns less easily available and less ubiquitous, they would make society safer.

A black trauma surgeon who treated the dying Dallas police officers, who were shot by a gunman during a protest against police brutality, made an emotional plea to end racial violence. (Reuters)