Republican presidential candidate Marco Rubio on Sunday said he bought another gun on Christmas Eve — to protect his family and himself from ISIS.

"I'm a strong supporter of the Second Amendment. I have a right to protect my family if someone were to come after us," Rubio said on Face the Nation, according to a video posted by ThinkProgress. "In fact, if ISIS were to visit us or our communities at any moment, the last line of defense between ISIS and my family is the ability that I have to protect my family from them, or from a criminal, or anyone else who seeks to do us harm. Millions of Americans feel that way."

But is this really a good way to protect your family? Consider two statistics: In the US, around 600 people, including about 110 children, die in accidental shootings each year. By comparison, fewer than 75 Americans died in terrorist attacks annually after 2001. Just based on these figures, it would seem like Rubio should worry about the potential repercussions of owning a firearm more than a terrorist attack.

More broadly, Rubio's comments advance the "good guy with a gun" myth: the idea that someone with a gun can stop shootings, so as many people as possible should buy firearms to protect themselves. But the empirical evidence is clear on this point: Getting more people to buy and own guns would likely lead to many more gun deaths.

More guns mean more gun deaths

The theory behind the mantra of "a good guy with a gun" is that more people should be armed so they can be ready to defend themselves and others from an active shooter.

But the research suggests that's plainly false: When there are more guns and gun owners, there are far more gun deaths. Studies have found this to be true again and again — for homicides, suicides, domestic violence, and violence against police.

Here's one chart, from a 2007 study by Harvard School of Public Health researchers, showing the correlation between statewide firearm homicide victimization rates and household gun ownership after controlling for robbery rates:

A more recent study from 2013, led by a Boston University School of Public Health researcher, reached similar conclusions: After controlling for multiple variables, the study found that a 1 percent increase in gun ownership correlated with a roughly 0.9 percent rise in the firearm homicide rate at the state level.

This holds up around the world. As Vox's Zack Beauchamp explained, a breakthrough analysis in the 1990s by UC Berkeley's Franklin Zimring and Gordon Hawkins found that the US does not, contrary to the old conventional wisdom, have more crime in general than other Western industrial nations. Instead, the US appears to have more lethal violence — and that's driven in large part by the prevalence of guns.

"A series of specific comparisons of the death rates from property crime and assault in New York City and London show how enormous differences in death risk can be explained even while general patterns are similar," Zimring and Hawkins wrote. "A preference for crimes of personal force and the willingness and ability to use guns in robbery make similar levels of property crime 54 times as deadly in New York City as in London."

THE US APPEARS TO HAVE MORE LETHAL VIOLENCE — AND THAT'S DRIVEN IN LARGE PART BY THE PREVALENCE OF GUNS

This is, in many ways, intuitive: The prevalence of guns can cause petty arguments and conflicts to escalate into deadly encounters. People of every country get into arguments and fights with friends, family, and peers. But in the US, it's much more likely that someone will get angry during an argument, pull out a gun, and kill someone.

These three studies aren't the only ones to reach similar conclusions. Multiple reviews of the research, including the Harvard Injury Control Research Center's aggregation of the evidence, have consistently found a correlation between gun ownership and gun deaths after controlling for other factors.

So chances are a good guy with a gun will not stop a bad guy with a gun. In fact, trying to produce more good guys with guns could make gun deaths far, far more frequent.

Watch: America's biggest gun problem is the one we never talk about