Back in the heyday of the British Empire, a man from one of the colonies addressed a London audience. "Please do not do any more good in my country," he said. "We have suffered too much already from all the good that you have done." That is essentially the message of an outstanding new book by Jason Riley about blacks in America. Its title is "Please Stop Helping Us." Its theme is that many policies designed to help blacks are in fact harmful, sometimes devastatingly so. These counterproductive policies range from minimum wage laws to "affirmative action" quotas. This book...