More than 100 people die from gunshots on an average day in America. In June, the surgeon general declared gun violence a public health crisis. It’s the leading cause of death for children 17 and younger. The Centers for Disease Control and Prevention reported there were 48,000 deaths from firearms in 2022, 40% of which were homicides. Yet many Americans believe owning a gun makes them safer: Self-defense is the number one reason given for owning one.

In the precedent-reversing 2022 New York State Rifle & Pistol Association v. Bruen decision, which struck down a restriction on who could carry a handgun in New York, justices cited an unpublished survey that seemed to show guns are used over a million times a year in self-defense. That survey, by Georgetown University researcher William English, was funded by the gun lobby.

English found so many defensive uses of guns in part because he allowed survey respondents to define self-defense. But David Hemenway, a professor of public health at Harvard, says it can be a problem to define self-defense so broadly. Hemenway has also done surveys asking people about their defensive use of guns, and he says most are not defending themselves against a mugger or a rapist. They are more like the subject who told him he got his gun after arguing with a neighbor who threw a beer. Is that self-defense?

To look more directly at how guns may be used by innocent people to defend themselves from criminals, he and other researchers have looked to a data set from the National Crime Victimization Survey, put together yearly by the Census Bureau and Department of Justice. People are asked whether they were victims of a crime or attempted crime and how they responded. The results show that in cases where a person was present during a crime attempt, about 1% responded by using or brandishing a gun.

What’s often missed in surveys such as English’s, said Stanford University law professor John Donohue, are cases where something went horribly wrong. He’s thinking of a man responding to a break-in and shooting his 16-year-old son by mistake, or a man who used a gun to pursue someone who robbed him at an ATM, in the process shooting a 9-year-old girl.

Other researchers have asked: Does having a gun make you safer? In 2017, 75% of gun owners told Pew Research it did.

Donohue was impressed by a 2022 study by David Studdert comparing gun-owning households and gun-free households in comparable neighborhoods which showed gun-owning households were twice as likely to die by homicide. In the Pew survey, gun owners were three times as likely to have been shot as non-gun owners.

In 2009, professor Charles Branas gathered data on shootings in Philadelphia from 2003-06. He compared the victims to a control group matched for age, sex and race who had not been shot. His results showed shooting victims were four times as likely as non-victims to be carrying a gun at the time.

Cause and effect are hard to tease out. The correlation might be explained by gun owners feeling braver and avoiding de-escalation because they felt protected by their firearm.

Suicides by guns have spiked during the last decade and make up the majority of gun-related deaths. Experts say many of these are impulsive acts by people who might have had a chance to recover from their suicidal thoughts if a gun weren’t available.

The cost of gun proliferation is clear in terms of homicides, suicides and accidents, but it’s harder to compute the other side of the balance — the benefits people derive from the ability to protect themselves.

The pro-gun side is assuming that in these allegedly defensive gun uses, someone would have been hurt or killed if not for their gun. The most careful studies show those assumptions are wrongheaded.

Neither Hemenway nor Donohue have come across any studies showing more firearms make for a safer or healthier society — and no evidence the proliferation of semiautomatic rifles make people safer.

English wrote guns like the AR-15 were “rather ideal for home defense,” which was the primary reason people say they buy them. Yet these are guns developed to kill on the battlefield — as Hemenway puts it, “to rip up your insides.” Donohue pointed out the defensive benefits of such guns is “zero.” And because these guns can shoot through walls, they create more potential for hurting innocent bystanders.

Investigators are searching for missed signs that would have identified the shooter in Butler before his assassination attempt, but so far they’ve found nothing in the way of motive. Except of course that he was a loner, possibly troubled, and thanks to his parents’ gun collection, had easy access to a dangerous weapon.

F.D. Flam is a Bloomberg Opinion columnist covering science and host of “Follow the Science” podcast.