The political handling of conflict presupposes its own standards. These are less precise than the technical languages of law and economics, and there is a persistent danger that the political realm be colonized by the standards of legality or economic efficiency. This lecture explores the tension, relying on Aquinas’s account of law, and drawing on his analogical discussion of the many types of law to underline the importance of preserving a distinct realm of political reasonableness as a requirement of the common good.