A distinguished and experienced appellate court judge, Richard A. Posner offers in this new book a unique and, to orthodox legal thinkers, a startling perspective on how judges and justices decide cases. When conventional legal materials enable judges to ascertain the true facts of a case and apply clear pre-existing legal rules to them, Posner argues, they do so straightforwardly; that is the domain of legalist reasoning. However, in non-routine cases, the conventional materials run out and judges are on their own, navigating uncharted seas with equipment consisting of experience,...