Collective action problems arise when the individually rational course of action produces outcomes that are collectively irrational or harmful. The prisoner's dilemma is the canonical model: two players, each choosing independently between cooperation and defection, reach a mutually worse outcome than if they had cooperated — because neither can trust the other. Garrett Hardin's 'tragedy of the commons' applied this logic to shared resources: without coordination, individually rational exploitation leads to collective ruin. Elinor Ostrom, however, showed that communities frequently solve these problems without either privatisation or state control — through norms, monitoring, and graduated sanctions. The lesson for climate, antibiotic resistance, tax avoidance, and arms races is the same: moral appeals are insufficient. The structure of incentives must change, and that requires institutional design.

💡 Did you know? Elinor Ostrom won the Nobel Prize in Economics in 2009 — the first woman to do so. Her research was based not on abstract modelling but on meticulous fieldwork studying how communities around the world actually managed fisheries, forests, and irrigation systems.