The “collective action problem†describes situations where each person in a group can individually profit more by withholding contributions to group goals. However, if all act in their material self-interest no public good is produced and all are worse off. I present a new solution to...

This paper experimentally explores how the enforcement of cooperative behavior in a social dilemma is facilitated through institutional as well as emotional mechanisms. Recent studies emphasize the importance of negatively valued emotions, such as anger, which motivate individuals to punish free...

In a semi-aggregative representation of a game, the payoff of a player depends on a player's own strategy and on a personalized aggregate of all players' strategies. Suppose that each player has a conjecture about the reaction of the personalized aggregate to a change in the player's own...

We analyze group contests for public goods by applying the solution concept of an evolutionary stable strategy (ESS). We show that a global ESS cannot exist, because a mutant free-rider can always invade group behavior successfully. There does exist, however, a unique local ESS, which we...

This paper presents a formal theory of reciprocity. Reciprocity means that people reward kind actions and punish unkind ones. The theory takes into account that people evaluate the kindness of an action not only by its consequences but also by the intention underlying this action. The theory...

In this paper we show that a simple model of fairness preferences explains major experimental regularities of common pool resource (CPR) experiments. The evidence indicates that in standard CPR games without communication and without sanctioning possibilities inefficient excess appropriation is...

Problems which can only be resolved through international cooperation are increasing. Due to this increase, states cooperate more than ever with each other and with international organizations (IOs) but often insufficiently to solve the problems. When social scientists analyze the potential for...