Frederick Joseph is a marketing guru, an Elizabeth Warren campaign surrogate, and the author of a 2020 book, The Black Friend: On Being a Better White Person. He is black. Over the weekend, he took his dog for a walk with his fiance in a New York City park, in the Williamsburg neighborhood of Brooklyn. There the couple encountered a white woman, later identified as Emma Sarley. It's not clear exactly what happened, but a disagreement broke out—Joseph claims that Sarley wrongly thought the dog was barking too loudly—and Sarley flipped Joseph the bird before stomping off. But according to...