The world is complex, Richard Posner observes in his most recent book, Reflections on Judging. It follows that, to resolve real-world disputes sensibly, judges must be astute students of the world’s complexity. The problem, he says, is that, thanks to disposition, training, and professional incentives, they aren’t. Worse than that, the legal system generates its own complexity precisely to enable judges “to avoid rather than meet and overcome the challenge of complexity” that the world delivers. Reflections concerns how judges needlessly complexify inherently simple law, and how this complexification can be corrected. Posner’s diagnoses and prescriptions range widely—from the Bluebook to the law school curriculum. But the principal culprit,...