Black Lives Matter, the slogan of the movement that began in earnest after the police shooting of Michael Brown in Ferguson, Mo., is a lie. Taken at face value, the phrase is a truism, since obviously all lives matter. But the people who use it as a shibboleth don’t care about black lives per se so much as scoring points against the police. When there is some awful tragedy involving a cop shooting or harming a young black man (sometimes justifiably, sometimes not), they muster every ounce of their moral dudgeon and stage demonstrations eagerly covered by a sympathetic media....