Republican presidential candidate Donald Trump wants gun owners to know that he has their backs. To make that clear Trump endorsed the National Rifle Association's argument that the answer to stopping mass shootings is a "good guy with a gun," and he applied it to an international tragedy. At a conference hosted by the NRA's legislative institute, he said that the ISIS attacks that killed 130 people in Paris, many by gunfire, could have been stopped if someone was carrying a gun.

"It might not have happened, because if they knew guns were in the room, it might not have happened," he said.

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Trump blamed France's tough gun laws. He also went on to say the same thing about last year's San Bernardino tragedy in California, where a married couple shot and killed 14 people in the name of ISIS.

But is that true?

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Now we have to get into some Trump logic. It appears that Trump is implying that if France had less restrictive gun laws, the terrorists would have assumed some of their targets had guns as well. Based on that rationale, he appears to be saying that the terrorists may not have carried out the attacks, if they "knew guns were in the room." The logic is that gun-friendly policies prevent murders because killers assume someone will shoot back.

While there is no way to know if this is anecdotally true in the particular situations Trump mentioned in his speech, we do know some things about murder rates and gun laws. First of all, France has a lower murder rate than the U.S. and more restrictive gun laws, according to The Guardian.

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U.S. states with some of the more gun-friendly laws, like Louisiana, and Mississippi have higher rates of murder by firearm compared to other states. Using Trump's apparent logic of the Paris attacks, states like these with gun-friendly laws should have the lowest rates of firearm murders. The argument would be that killers would assume victims are carrying guns, and avoid the confrontation. However, it appears that at least in the U.S., knowledge that someone could have a gun does not prevent murder.

Associated Press

Trump's comments came after officially getting the endorsement of the National Rifle Association and opening remarks by NRA President Wayne LaPierre, where he repeated his controversial mantra, "the only way to stop a bad guy with a gun is with a good guy with a gun."

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LaPierre has made this argument after mass shootings and also uses it as a slogan for personal safety. However, according to a study published in the American Journal of Epidemiology, you are more likely to die in a home invasion, if you keep a gun in the home.

Trump's past on guns.

Hopefully, for Trump, the NRA supporters won't remember the things he said about guns in the past.

In 2012, after the mass shooting of more than 20 people, mostly young children, at an elementary school in Newtown, Connecticut Trump agreed with President Obama's call for gun control.

Also, in his 2000 book "The America We Deserve" he wrote about his support for a ban on assault weapons.

"I generally oppose gun control, but I support the ban on assault weapons and I also support a slightly longer waiting period to purchase a gun," he said, according to ABC News. "With today’s internet technology we should be able to tell within seventy-two hours if a potential gun owner has a record.”

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