In the language of today’s National Rifle Association, “an armed society is a polite society.” The aphorism, borrowed from the science-fiction author Robert Heinlein, is the inspiration for one of the N.R.A.’s most popular T-shirts, which bears the word “COEXIST,” spelled out in brightly colored ammo cartridges and guns. To promote the shirt ($17.99), the N.R.A. store says that Heinlein’s quote “emphasizes the independent, tolerant nature of gun owners in a fun and thought-provoking way.”

It is a vision at the heart of the modern gun movement: the more that society makes the threat of violence available to us, the safer we will be. In forty-eight hours this week, the poisonous flaw in that fantasy has been exposed from multiple angles: on Tuesday, two police officers in Baton Rouge, Louisiana, fatally shot a black man, Alton Sterling, while trying to arrest him. Some reports say that, before police arrived, he was openly carrying a gun, which, under the makeshift patchwork of American gun law, would have afforded him more legal protection, not less. Louisiana is one of the forty-five states that allow residents to carry firearms openly in public, and though Sterling was a convicted felon (and therefore probably ineligible to obtain a concealed-carry permit) police could not have known his criminal record before investigating him. It was absurd not to ask whether a white man, exercising his right to open carry, would have been approached differently.

The next day, during a traffic stop in Falcon Heights, Minnesota, a police officer fatally shot a black man, Philando Castile, who, according to his girlfriend, Diamond Reynolds, was licensed to carry a concealed firearm. According to Reynolds, who was in the car and broadcast the aftermath on Facebook, Castile had told the officer that he was carrying his gun, but when Castile reached for his license and registration, he was shot. In the hours that followed, as America turned, once again, to the ritual of mourning the killings of black men by police officers, the N.R.A. was silent. Its official Twitter feed, which often draws attention to cases of police questioning gun owners for exercising the right to carry, said nothing, even as the silence became conspicuous. (@CoolJ90: “@NRA care to come to the defense of a man murdered by police who had a license to carry his weapon?”)

For critics of the N.R.A., it was an awkward exposure of what is usually left unsaid: the organization is far less active in asserting the Second Amendment rights of black Americans than of white ones.