Economists are vocal proponents of the simplistic scientific method. If they can’t present their work as experimental, they strive to label it “quasi-experimental.” But if you read an introductory economics text, virtually none of the content is based on experiments. Instead, good economics texts are packed with truisms based on calm observation of humanity: incentives change behavior, trade is mutually beneficial, supply slopes up, demand slopes down, excess supply leads to surpluses, excess demand leads to shortages, externalities lead to inefficiency. These lessons are as undeniable as “the heart pumps blood” and “the stomach digests food.” But they’re nevertheless supremely insightful and useful. Designing social institutions without considering incentives is as absurd trying to stuff food down people’s lungs.