Gage Skidmore from Peoria, AZ, United States of America · CC BY-SA 2.0

Trained as a physicist but made his name arguing, in The Machinery of Freedom, that markets could supply not just goods but law and order itself — a fully worked-out theory of anarcho-capitalism built without ever taking a formal class in economics or law. Friedman taught law at Santa Clara University for over a decade while writing textbooks on price theory and legal economics that treated everyday habits and legal systems alike as problems markets could illuminate. He is the son of Nobel laureate economists Milton and Rose Friedman, and has also written fantasy fiction on the side.