This paper investigates the efficacy of a punishment mechanism in promoting cooperative behaviour in a public goods game when enforcement of punishment is uncertain. Experimental studies have found that a sanctioning system can induce individuals to adopt behaviour deemed as socially acceptable....

In the Solidarity Game (Selten and Ockenfels, 1998), two "rich" persons can support a "poor" one. A strong positive correlation between one rich person's solidarity contribution and his expected contribution of the other is observed. This paper investigates the causality behind this correlation....