This paper asks whether population growth is conducive to the sustainability of cooperation. A simple model is developed in which farmers who live around a circular lake engage in trade with their adjacent neighbors. The payoffs from this activity are governed by a prisoner's dilemma "rule of...

Field evidence suggests that people belonging to the same group often behave similarly, i.e., behavior exhibits social interaction effects. We conduct a laboratory experiment that avoids the identification problem present in the field and allows us to study the behavioral logic of social...