Ecologist Garrett Hardin's 1968 essay described a shared, unregulated pasture where every herder benefits fully from adding one more animal, while the cost of overgrazing is spread across everyone. Because the personal gain is immediate and the shared cost is diffuse, each rational herder keeps adding animals — and the pasture that supports them all collapses.
Elinor Ostrom won the 2009 Nobel Memorial Prize in Economic Sciences for showing that real communities often avoid this tragedy through self-governed rules, monitoring and graduated sanctions — without needing privatisation or top-down regulation.
A shared pasture where self-interested herders each graze as much as they can, driving total grass biomass down faster than it can regrow — unless the group agrees to a sustainable quota.
Every patch of grass regrows logistically toward full health on its own, but herders act independently, each maximising their own harvest. Total consumption scales with herder count and harvest rate, and once it exceeds the pasture's regrowth capacity, biomass collapses.
Adjust the number of herders and their harvest rate against the grass regrowth rate, and watch the pasture's colour and height respond in real time. Toggle the sustainable quota to see how a shared limit keeps the commons healthy.
Elinor Ostrom's Nobel-winning research found that real-world commons — fisheries, irrigation systems, forests — are often managed sustainably by the communities that depend on them, through locally agreed rules rather than privatisation.