Displaying 14 Items

Groups in Conflict: Size Matters, But Not In The Way You Think

(with Laura Mayoral), December 2017.

Summary. This paper studies costly conflict over private and public goods. Oil is an example of the former, political power an example of the latter. Groups involved in conflict are likely to be small when the prize is private, and large when the prize is public. We examine these implications empirically by constructing a global dataset at the ethnic group level and studying conflict along ethnic lines. Our theoretical predictions find significant confirmation in an empirical setting

Conflict and Development

(with Joan Esteban) Annual Reviews of Economics  9, 263-293, 2017.

Summary. In this review, we examine the links between economic development and social conflict. By economic development, we refer broadly to aggregate changes in per capita income and wealth or in the distribution of that wealth. By social conflict, we refer to within-country unrest, ranging from peaceful demonstrations, processions, and strikes to violent riots and civil war. We organize our review by critically examining three common perceptions: that conflict declines with ongoing economic growth; that conflict is principally organized along economic differences rather than similarities; and that conflict, most especially in developing countries, is driven by ethnic motives.


CesIfo Economic Studies 2015.

Summary. Yes, capital must displace labor, but not because r > g. This article is based on this blog post, Branko Milanovic objected here; I replied. Piketty replies to some of his critics here.


Implications of an Economic Theory of Conflict: Hindu-Muslim Violence in India

(with Anirban Mitra), Journal of Political Economy 122, 719-765, 2014.

Summary. We model intergroup conflict driven by economic changes within groups. We show that if group incomes are low, increasing group incomes raises violence against that group and lowers violence generated by it. We then apply the model to data on Hindu-Muslim violence in India. Our main result is that an increase in per capita Muslim expenditures generates a large and significant increase in future religious conflict. An increase in Hindu expenditures has a negative or no effect. These findings speak to the origins of Hindu-Muslim violence in post-Independence India. Online Appendix.

Ethnicity and Conflict: An Empirical Study

(with Joan Esteban and Laura. Mayoral), American Economic Review 102, 1310-1342, 2012. Online Appendix.

Summary. We examine empirically the impact of ethnic divisions on conflict, by using a specification based on Esteban and Ray (2011). That theory links conflict intensity to three indices of ethnic distribution: polarization, fractionalization, and the Gini-Greenberg index. The empirical analysis verifies that these distributional measures are significant correlates of conflict. These effects persist as we introduce country-specific measures of group cohesion and of the importance of public goods, and combine them with the distributional measures exactly as described by the theory.

Ethnicity and Conflict: Theory and Facts

(with Joan Esteban and Laura Mayoral), Science 336, 858 – 865, 2012.

Summary. Over the second half of the 20th century, conflicts within national boundaries became increasingly dominant. Many (if not most) such conflicts involved violence along ethnic lines. On the basis of recent theoretical and empirical research, we provide evidence that preexisting ethnic divisions do influence social conflict. Our analysis also points to particular channels of influence. Specifically, we show that two different measures of ethnic division—polarization and fractionalization—jointly influence conflict, the former more so when the winners enjoy a “public” prize (such as political power or religious hegemony), the latter more so when the prize is “private” (such as looted resources, government subsidies, or infrastructures).

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.

Comparing Polarization Measures

(with J. Esteban), M. Garfinkel and S. Skaperdas (eds), Oxford Handbook of the Economics of Peace and Conflict, Oxford University Press, 2011.

Summary. We review some alternative measures of unidimensional polarization, grouped into two families: polarization and bi-polarization measures. We take as a base for our analysis the set of axioms that characterize the measure of polarization developed in Esteban and Ray (Econometrica 1994) and Duclos, Esteban and Ray (Econometrica 2013),

A Model of Ethnic Conflict

(with Joan Esteban),  Journal of the European Economic Association 9, 496–521, 2011.

Summar. We present a model of conflict in which discriminatory government policy or social intolerance is responsive to various forms of ethnic activism, including violence. The model allows for both financial and human contributions to conflict and allows for a variety of individual attitudes (“radicalism”) towards the cause. The main results concern the effects of within-group heterogeneity in radicalism and income, as well as the correlation between radicalism and income, in precipitating conflict.

Costly Conflict Under Complete Information

unpublished manuscript, June 2009.

Summary. This paper studies costly conflict in a world of complete information, in which society can commit to divisible transfers among all potentially warring groups. The difficulty in preventing conflict arises from the possibility that there may be several conflictual divisions of society, each based on a different marker, such as class, geography, religion, or ethnicity. It is shown that this diversity of societal markers is particularly conducive to social instability when potential conflict is over private, divisible resources. In contrast, when conflict is over public goods, such diversity promotes social stability.

On the Salience of Ethnic Conflict

(with Joan Esteban), American Economic Review 98:5, 2185–2202, 2008. Online Appendix.

Summary. “In much of Asia and Africa, it is only modest hyperbole to assert that the Marxian prophecy has had an ethnic fulfillment.” — Donald Horowitz (1985).

Polarization, Fractionalization and Conflict

(with Joan Esteban), Journal of Peace Researc45, 163-182, 2008.

Summary. We provide a theoretical framework that distinguishes between the occurrence of conflict and its severity, and clarifies the role of polarization and fractionalization in each of these cases.

An Extension of a Measure of Polarization, With an Application to the Income Distribution of Five OECD Countries

(with Joan Esteban and Carlos Gradín), Journal of Economic Inequality 5, 1–19, 2007.

Summary. We introduce an extension of the Esteban and Ray [Econometrica, 62:819–851 1994] measure of polarization that can be applied to density functions. As a by-product we also derive the Wolfson [Am. Econ. Rev., 84:353–358 1994] measure as a special case. This derivation has the virtue of casting both measures in the context of a (statistically) unified framework. We study the polarization of the distribution of household income for five OECD countries (LIS database): US, UK, Canada, Germany and Sweden.

Aspirations, Poverty and Economic Change

in Abhijit Banerjee, Roland Benabou and Dilip Mookherjee, What Have We Learned About Poverty?, Oxford University Press, 2006.

Summary. Introduces the idea of aspirations as a socially determined reference point. The paper argues that reachable aspirations serve to inspire, while still higher aspirations could lead to frustration.

Polarization: Concepts, Measurement, Estimation

(with Jean-Yves Duclos and Joan Esteban), Econometrica 72, 1737–1772, 2004.

Summary. We develop the measurement theory of polarization for the case in which income distributions can be described using density functions. The main theorem uniquely characterizes a class of polarization measures that fits into what we call the “identity-alienation” framework, and simultaneously satisfies a set of axioms. Here is a link to a somewhat expanded version, which was published in C. Barrett (ed), The Social Economics of Poverty: Identities, Groups, Communities and Networks, London: Routledge (2005).

Collective Action and the Group Size Paradox

(with Joan Esteban), American Political Science Review  95, 663–672, 2001.

SummaryAccording to the Olson paradox, larger groups may be less successful than smaller groups in furthering their interests. We address the issue in a model with three distinctive features: explicit intergroup interaction, collective prizes with a varying mix of public and private characteristics, and nonlinear lobbying costs. The interplay of these features leads to new results. When the cost of lobbying has the elasticity of a quadratic function, or higher, larger groups are more effective no matter how private the prize. With smaller elasticities, a threshold degree of publicness is enough to overturn the Olson argument, and this threshold tends to zero as the elasticity approaches the value for a quadratic function. 

Social Decision Rules are Not Immune to Conflict

(with Joan Esteban), Economics of Governance 2, 59–67, 2001.

Summary. Why is rent-seeking so endemic in societies? Might it not be possible to design a Pareto-improving social decision rule that sidesteps the inefficient waste of resources resulting from conflict? We assume that a benevolent planner knows the effectiveness of each rent-seeker, that the cost of expending resources is isoelastic, and that it is the same across all players. But she does not know the precise value of this elasticity. We show that this minimal lack of information leads to the impossibility of a Pareto-improving social decision rule, as long as there are at least four agents.

Conflict and Distribution

(with Joan Esteban), Journal of Economic Theory 87, 379-415, 1999.

Summary. We develop a behavioral model that links the level and pattern of social conflict to the society-wide distribution of individual characteristics. The model can be applied to groups that differ in characteristics such as wealth, ethnicity, religion, and political ideology. We settle questions of existence and uniqueness of conflict equilibrium. Conflict is seen to be closely connected with the bimodality of the underlying distribution of characteristics. However, in general, the conflictdistribution relationship is nonlinear and surprisingly complex. Our results on conflict patterns also throw light on the phenomena of extremism and moderation.

On the Measurement of Polarization

(with Joan Esteban), Econometrica  62, 819–851, 1994.

Summary. This paper is concerned with the conceptualization and measurement of polarization. Suppose that a population is grouped into significantly-sized “clusters’,” such that each cluster is “similar” in terms of the attributes of its members, but different clusters have “dissimilar” attributes. In that case we would say that the society is “polarized.” We study these intuitive criteria carefully, and provide a theory of measurement.