The pool is waiting
Step once to see what the agents request and what the pool can afford.
Change one rule
One run is a story. Twelve independent seeds show whether the story survives luck.
Run the batch to compare collapse and ending-resource spread.
Same pool, different asks
A tragedy is a mechanism, not a personality test
The pool does not need a villain. It needs demand to outrun recovery.
Different game, different claim
This model is different from The Commons Drain. There, agents contribute to a shared pot and the problem is free riding. Here, agents harvest from a living pool. The resource can regenerate, but regeneration is weakest when the pool is already nearly empty. The same word—commons—can hide two different mechanisms, and a useful simulation should make that difference visible.
Understandable choices can still add up badly
A group can be made of perfectly understandable agents and still exhaust what they share. The maximum harvester asks for what is available. The steward asks for a share of expected growth. The threshold protector cuts back when health falls. None of these rules has to be irrational for the resource to enter a downward spiral. What matters is the relationship between request, recovery, and the moment at which each agent decides.
What this model is not
It is not a forecast of a real meadow, fishery, climate system, or community. It leaves out institutions, communication, unequal power, property rights, enforcement, and the many ways people redesign a commons. It is a small instrument for isolating one question: when a pool regenerates but demand is immediate, which rules leave enough behind? A single run is an illustration. Change the seed or the rule and the conclusion should survive its own variation—or it should be withdrawn. The point is not to turn a curve into a prophecy. The point is to make the hidden dependency visible: every request changes the starting point from which the next request is made. Institutions can change that dependency; this page shows why they matter. A model earns trust by making its omissions easy to name, not by hiding them behind a polished chart.
Reading behind the model
- Hardin, G. (1968). The tragedy of the commons. Science, 162(3859), 1243–1248.
- Janssen, M. A., & Ostrom, E. (2006). Empirically based, agent-based models. Ecology and Society, 11(2), 37.
- Ostrom, E. (1990). Governing the commons. Cambridge University Press.
- Ostrom, E., Gardner, R., & Walker, J. (1994). Rules, games, and common-pool resources. University of Michigan Press.
- Rockström, J., et al. (2009). A safe operating space for humanity. Ecology and Society, 14(2), 32.