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 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 present the first causal evidence on the persistent impact of enduring competition on prosociality. Inspired by the literature on tournaments within firms, which shows that competitive compensation schemes reduce cooperation in the short-run, we explore if enduring exposure to a competitive...

The provision of social incentives in the workplace, where performance benefits a charitable cause, has been frequently used in modern organizations. In this paper, we quantify the impact of social incentives on performance under two incentive schemes: piece rate and a winner-take-all...

We show that warm-glow motives in provision by competing suppliers can lead to inefficient charity selection. In these situations, discretionary donor choices can promote efficient charity selection even when provision outcomes are non-verifiable. Government funding arrangements, on the other...

We consider dynamic competition among platforms in a market with network externalities. A platform that dominated the market in the previous period becomes "focal" in the current period, in that agents play the equilibrium in which they adopt the focal platform whenever such equilibrium exists....

The effects of (private, small-scale) piracy on the pricing behavior of producers of information goods are studied within a unified model of vertical differentiation. Although information goods are assumed to be perfectly horizontally differentiated, demands are interdependent because the...

This paper develops a theory of oligopoly and markups in general equilibrium. Firms compete in a network of product market rivalries that emerges endogenously out of the characteristics of the products and services they supply. My model embeds a novel, highly tractable and scalable demand system...

We model competition on a credence market governed by an imperfect label, signaling high quality, as a rank-order tournament between firms. In this market interaction, asymmetric firms jointly and competitively control the underlying quality ranking's precision by releasing individual...

In many markets, sellers advertise their good with an asking price. This is a price at which the seller will take his good off the market and trade immediately, though it is understood that a buyer can submit an offer below the asking price and that this offer may be accepted if the seller...