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 paper provides a complete characterization of equilibria in a game-theoretic version of Rothschild and Stiglitz's (1976) model of competitive insurance. I allow for stochastic contract offers by insurance firms and show that a unique symmetric equilibrium always exists. Exact conditions...

This study explores mechanism design with allocation-based social preferences. Agents’ social preferences and private payoffs are all subject to asymmetric information. We assume quasi-linear utility and independent types. We show how the asymmetry of information about agents’ social...

We explore mechanism design with outcome-based social preferences. Agents' social preferences and private payoffs are all subject to asymmetric information. We assume quasi-linear utility and independent types. We show how the asymmetry of information about agents' social preferences can be...

We introduce the give-or-destroy game that allows us to fully elicit an individual's social preference schedule. We find that about one third of the population exhibits both pro-social and anti-social preferences that are independent of payoff comparisons with those who are affected. We call...

For decades, experimental economics has been very interested in behavior that could be characterized as practicing solidarity (although the term is rarely used). Solidarity is a key concept in Catholic Social Teaching. This paper builds a bridge between these two endeavors that, thus far, had...

Can social norms affect fundamental patterns of behavior such as income effects? Studies of determinants of giving to charities and other individuals yield a wide range of income-effect estimates. We conduct two experiments to first test whether the effect of income on charitable giving depends...

This paper develops a positive model of informal contracting in which rewards and punishments are not determined by an ex ante optimal plan but instead express the ex post moral sentiments of the arbitrating party. We consider a subjective performance evaluation problem in which a principal can...

The goal of this paper is to draw some lessons for economic theory from research in psychology, social psychology and, more briefly, in biology, which purports to explain the formation of social preferences. We elicit the basic mechanisms whereby a variety of social preferences are determined in...

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.