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.

We study full implementation with evidence in an environment with bounded utilities. We show that a social choice function is Nash implementable in a direct revelation mechanism if and only if it satisfies the measurability condition proposed by Ben-Porath and Lipman (2012). Building on a novel...

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...

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...

Charitable donations provide positive externalities and can potentially be increased with an understanding of donor preferences. We obtain a uniquely comprehensive characterization of donation motives using an experiment that varies treatments between and within subject. Donations are increasing...

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...

Charitable fundraisers frequently announce giving by others, and research shows that this can increase donations. However, this mechanism may not put information about peers to the most efficient use if it is costly to inform individuals who are indifferent to peer actions or causes some...