For much of modern political history, the most dangerous words in public policy have not been shouted slogans but soothing reassurances. They are the claims that certain policies are “compassionate,” “progressive,” or “humane,” offered without any serious accounting of how they actually affect the people forced to live under them. This pattern is particularly evident in the agenda of today’s Democratic Party, whose policy choices increasingly produce chaos and danger while being marketed as moral advances. The central flaw is not malice so much as indifference to consequences. The pursuit of ideological purity has replaced the traditional liberal concern for...