Altruists and envious people who meet in contests are symbionts. They do better than a population of narrowly rational individuals. If there are only altruists and envious individuals, a particular mixture of altruists and envious individuals is evolutionarily stable.

This study argues that parents have a desire for dividing equally between their children, and that this motive applies to transfers of gifts inter vivos. We suggest that the equal division motive competes with traditional altruism: support to the child or the children with greatest needs. When...

In public good games, voluntary contributions tend to start off high and decline as the game is repeated. If high contributors are matched, however, contributions tend to stay high. We propose a formalization predicting that high contributors will self-select into groups committed to charitable...

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...

We show that once interfamily exchanges are considered, Becker's rotten kids mechanism has some remarkable implications that have gone hitherto unnoticed. Specifically, we establish that Cornes and Silva's (1999) result of efficiency in the contribution game amongst siblings extends to a setting...

Empirical evidence is provided for the importance of non-reciprocal pro-social behavior of individuals in an anonymous, n-person pure public good setting. A unique panel data set of 136,000 observations is matched with an extensive survey. Even under anonymous conditions, a large number of...

This paper combines several large-scale surveys with different identification strategies to shed new light on the determinants of cooperative behavior. We provide evidence indicating that the well-being maximizing level of trust is above the income maximizing level. Higher trust is also linked...

Allowing for a free choice of the recipient's gender in a dictator game (N = 508), we find that women show a substantial gender biased towards females. Adding a charity recipient to the possible choices, the charity becomes the primary recipient and overall transfers increase. Yet, conditioning...

Fundraising interventions may lift donations and/or shift their composition and timing, making it important to study their effect across charity space and time. We find that major fundraising appeals lift total donations, but surprisingly shift donations to other charities across time. To...

We report experimental findings on the role of charitable promises in bargaining settings. We vary the enforceability of such promises within variants of ultimatum games where the proposer suggest a split between himself, the responder and a char-itable donation. By reneging on initial pledges,...