2025 Zayira Ray
Julius Silver Professor, Faculty of Arts and Science,
Professor of Economics, New York University
Research Associate, NBER
Part-Time Professor, University of Warwick
Research Fellow, CESifo
Spool Member, ThReD

Department of Economics, 
New York University,
19 West 4th Street
New York, NY 10012, U.S.A.
debraj.ray@nyu.edu, +1 (212)-998-8906.

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Oxford University Press, 2008. This book is now open-access; feel free to download a copy, and to buy the print version if you like the book.
≋ Three Randomly Selected Papers
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Collective Dynamic Consistency in Repeated Games

Games and Economic Behavior 1, 295-326, 1989

We formalize the notion of collective dynamic consistency for noncooperative repeated games. Intuitively, we require that an equilibrium not prescribe any course of action in any subgame that players would jointly wish to renegotiate, given the restriction that any alternative must itself be invulnerable to subsequent deviations and renegotiation. While the appropriate definition of collective dynamic consistency is clear for finitely repeated games, serious conceptual difficulties arise when games are infinitely repeated.

Linking Conflict to Inequality and Polarization

(with Joan Esteban), American Economic Review 101, 1345–1374, 2011.

Summary. In this paper we study a behavioral model of conflict that provides a basis for choosing certain indices of dispersion as indicators for conflict. We show that a suitable monotone transform of the equilibrium level of conflict can be proxied by a linear function of the Gini coefficient, the Herfindahl-Hirschman fractionalization index, and a specific measure of polarization due to Esteban and Ray.

The Great Gatsby Curve: Upward Mobility, Persistence and Inequality

(with Garance Genicot and Laura Mayoral). December 2025.

Summary.  This paper revisits the Great Gatsby curve that connects inequality to mobility, using panel data spanning several countries and time periods. Existing literature observes that the intergenerational elasticity of earnings is positively correlated with inequality, implying that mobility (viewed as the negative of that elasticity) decreases with inequality. In sharp contrast, we show that measures of upward mobility, axiomatically based on progressivity in income growth rates, are robustly and positively associated with baseline inequality. While there is no logical contradiction here, our study highlights crucial differences between mobility measures based on (lower) persistence and those based on growth progressivity, and asks the reader to align their choice of measure with foundational criteria that they feel best describe “mobility.” Our findings offer a re-interpretation of the Gatsby curve through the lens of shared prosperity, and have implications for the evolution of inequality within countries.