On Wednesday, two journalists at a CBS affiliate in Roanoke, Virginia were murdered during a live interview with a city official for the station’s morning broadcast. The gunman, a disgruntled former employee, killed himself after posting point-of-view footage of the killing online. So far, the gun lobby hasn’t commented, but it’s not hard to imagine their response: “If only those journalists had been armed.”

It’s the same tired refrain whenever there is a high-profile shooting. Dozens of schoolchildren murdered by a madman? Arm the teachers. Americans picked off like fish in a barrel by a lunatic in a movie theater? Arm the ushers.

The televised Virginia shooting comes just days after a damning report out of the University of Alabama by professor Adam Lankford listing the United States number one in the world, by a wide margin, for public mass shootings. According to the study, the correlation between private firearm ownership and the rate of mass shootings in a society is almost perfect. The U.S. has the most guns; we have the most mass shootings. Other nations with high rates of firearm ownership also ranked high in the study.

On Lankford’s definition of a “mass shooting,” the incident in Virginia doesn’t even qualify. But Lankford’s study still challenges the deadly notion, peddled by the NRA and other gun fanatics, that “The only thing that can stop a bad guy with a gun is a good guy with a gun.”

Wayne LaPierre’s favorite folksy idiom about the good guy with a gun is challenged by facts and real-world anecdotes. FBI data on active shooters – defined as “an individual actively engaged in killing or attempting to kill people in a confined and populated area” – details 160 incidents between 2000 and 2013, 21 of which were stopped by unarmed bystanders, six of which were stopped by trained security or off-duty police, and only one of which was stopped by a proverbial “good guy with a gun” – himself a former Marine.

Even the conservative Washington Times, highlighting 11 incidents of gun heroism, lists mostly responses by trained law enforcement officials, minor incidents of protection from home invasion, and incidents where no shots were even fired.

Actually, it looks as though the best thing that stops a bad guy with a gun is the bad guy himself. In the 160 incidents in the FBI report, 40 percent of the suspects turned the gun on themselves. And if not suicide, peaceful surrender: Two of the most deadly mass shootings in history, the Aurora theater shooting and the Charleston church shooting, ended without incident.

The likely response from the gun lobby to these facts – provided they could be made to recognize the facts at all – would be that shootings happen in gun-free zones, where the good guys are forced to leave their guns behind. It’s a real scandal, on their view, that places like elementary schools ban guns. If only there were more guns there, we’d see more good guys with guns saving the day.

Except that even in instances where a good guy with a gun responds, things typically don’t go very well. Mere possession of a concealed carry permit doesn’t make a person a hero. In a chaotic, emergency situation where bullets are flying and people are running and screaming, things often go badly when an untrained would-be hero enters the fray. The presence of guns is also widely understood to escalate conflicts that might otherwise not have involved any shooting.

Superman is faster than a speeding bullet, but no human being is. Once a shot has been fired, some flesh somewhere is likely to be rended. And if the killer possesses, for instance, a perfectly legal AR-15 outfitted to fire 900 rounds per minute, by the time a good guy’s sidearm is pulled out and aimed, the bad guy’s gun has likely already fired dozens of bullets.

Commenting on whether the Virginia shootings present a need to reform our gun laws, presidential candidate Donald Trump said, “Whether it was with a gun or a knife or whatever it would’ve been, it would’ve been something.” This is another common argument from the gun lobby – that even if you keep guns out of the hands of criminals, they’ll find other ways to cause mayhem, such as stabbings.

This is almost certainly true. In England, which has tight restrictions on gun ownership for the vast majority of its population, 14,000 people are admitted to hospitals with stab wounds annually. But any gun fanatic who makes this argument is really showing their desperation. Knives are obviously not as deadly as guns; only 27 people in England died of their stab wounds as opposed to a whopping 32,000 gun deaths in the U.S.

Any way you slice the figures, more guns means more gun deaths. Knives are not as deadly as guns. Unless they are well trained, “good guys with guns” do not help in mass shootings. The gun lobby deals with a paranoid, deluded fantasy world where heroic concealed-carry holders’ aim is always true and criminals in the woodwork are champing at the bit for them to holster their weapons. Every politician who is too weak to stand up to the gun lobby and present the clear, easily understood facts has blood on his hands. And until something meaningful is done, their hands are only going to get bloodier.