The growing influence and arrogance of the social-justice crowd bothers Mr. Sowell, which is one of the reasons he wrote the book. “Someone once said that people on the political left think that they would do what God would do if he were as well-informed as they are,” he says. He’s especially vexed by the quashing of dissent. “The fatal danger of our times today is a growing intolerance and suppression of opinions and evidence that differ from the prevailing ideologies that dominate institutions, ranging from the academic world to the corporate world, the media and government institutions,” he writes. “Many intellectuals with high accomplishments seem to assume that those accomplishments confer validity to their notions about a broad swath of issues ranging far beyond the scope of their accomplishments.”