Bad Money, Bad Actors
The Principle Behind Gresham's Law and the Long Delay of Its Adoption
Abstract
Gresham's law, usually stated as "bad money drives out good," rests on a more general principle. When a rule or a gap in knowledge forces unequal things to pass at the same face value, the party who chooses what to tender passes the inferior and keeps the superior, so the inferior circulates and the superior withdraws. The principle was understood by Aristophanes in 405 BC, analyzed by Nicole Oresme in the 1350s and Nicolaus Copernicus in the 1520s, and implicit in Thomas Gresham's 1558 warning to Elizabeth I, yet it was named only in 1858, and its remedies were adopted late and in pieces.
This paper argues that the delay is not mainly a story of ignorance. Every remedy the principle implies, whether letting price reflect quality or making quality cheap to verify, destroys a rent, and the holders of that rent have repeatedly slowed adoption: debasing sovereigns, holders of mint privileges, clippers and melters, counterfeiters, and, in modern markets, sellers of fake credentials, lenders who blacklisted honest appraisers, and a lawyer who cultivated the regulator responsible for policing him. Drawing on monetary history, the economics of adverse selection, and public enforcement records, the paper restates the principle in general form, documents the lag between recognition and adoption across 9 episodes, and proposes design rules for verification reforms that anticipate the resistance the principle itself predicts.
Key findings
- Gresham never said "bad money drives out good." The famous wording comes later. His 1558 letter warns that the debasement "was the occasion thatt all your ffine goold was convayd ought of this your realme."
- The principle is more than 2,000 years old. Aristophanes made the point in the Frogs in 405 BC, Oresme and Copernicus analyzed it, and it still went unnamed until Henry Dunning Macleod in 1858.
- The lag was about money, not ignorance. Each cure, from milled coin edges to credential verification, ended a profitable rent, and those who collected it resisted.
- The same mechanism runs through modern credentials: diploma mills, mortgage appraisal, and attorney discipline. The paper traces 9 episodes and proposes reform rules built to survive the resistance.
Keywords
Gresham's law · bad money drives out good · adverse selection · rent seeking · credential fraud · verification · monetary history · professional regulation
The book is coming Q2 2027
This paper lays out the principle. Gresham's Law tells the story of one case.
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