When person A makes an offer to person B and B rejects it, then A may "lose face". This loss of face is assumed to occur only if B knows for sure of A's offer. While under some circumstances loss of face can be rationalized by the consequences for future reputation, it may also enter directly...

Costly signaling of commitment to a group has been proposed as an explanation for participation in religion and ritual. But if the signal’s cost is too small, freeriders will send the signal and behave selfishly later. Effective signaling may then be prohibitively costly. If the average level...

In existing models of direct democratic institutions, the median voter benefits, but representative politicians are harmed since their policy choices can be overridden. This is a puzzle, since representative politicians were instrumental in creating these institutions. I build a model of direct...

All rulers face political competition, both from rivals within their state, and from other states to which their subjects may exit. In a simple model, both kinds of competition are substitutes. Internal competition (democracy) benefits citizens by allowing them to replace rent-seeking rulers....

People exhibit group reciprocity when they retaliate, not against the person who harmed them, but against somebody else in that person's group. Group reciprocity may be a key motivation behind intergroup conflict. We investigated group reciprocity in a laboratory experiment. After a group...

In experiments, people behave more cooperatively when they are aware of an external threat, while in the field, we observe surprisingly high levels of cooperation and altruism within groups in conflict situations such as civil wars. We provide an explanation for these phenomena. We introduce a...