The formation of implicit contracts in labor markets with heterogeneous employees is studied. If layoffs occur, the firm finds it optimal to offer differing contracts to differing employees, with employees who place a higher priority on leisure accepting contracts with higher layoff probabilities. The firm can do so without violating the constraint that employees voluntarily sort themselves into these contracts. Under plausible assumptions, the contracts match the empirical observation that relatively low wage rates and high unemployment probabilities tend to be correlated. Finally, an average or composite wage rate varies over states of nature, calling into question the ability of implicit contracts models to account for the constant, representative wage rate often found in macroeconomic models.

This paper explores the questions of how economic theory can be used to design and interpret experiments and how experimental results can be used to construct and interpret economic theories. The relationship between economic theory and experiments is modeled and illustrated with examples from both theoretical and experimental work. The emphasis is on combing theory and experiment to the benefit of both.

This is a review article of Foundations of Human Sociality: Economic Experiments and Ethnographic Evidence from Fifteen Small-Scale Societies (Oxford University Press 2004) edited by Joseph Henrich, Robert Boyd, Samuel Bowles, Colin Camerer, Ernst Fehr, and Herbert Gintis.

This paper provides an introduction to how knowledge is modeled in economic contexts and the role played by the concepts of knowledge and common knowledge in economic analysis.

This paper develops an explanation of why bargainers often terminate negotiations in disagreement in spite of positive expected gains from continued negotiation. The key to the analysis is a model which embeds bargaining activity within a market. Agents are continually faced with the choice between continuing to bargain with an existing partner or searching for a new partner. Bargainers may then terminate negotiations without an agreement, in spite of positive expected gains from continued bargaining, because seeking a new bargaining partner promises a higher return.

Preferences exhibit relative consumption effects if a person's satisfaction with their own consumption appears to depend upon how much others are consuming. This paper examines a model of an evolutionary environment in which Nature optimally builds relative consumption effects into preferences in order to compensate for incomplete environmental information. Copyright Econometric Society 2004.