Group Inequality and the Severity of Civil Conflict

GROUP INEQUALITY AND THE SEVERITY OF CIVIL CONFLICT JOHN D. HUBER AND LAURA MAYORAL1 January 1, 2019 ABSTRACT Civil conflicts, which have been much more prevalent than inter-state conflicts over the last fifty years, vary enormously in their intensity, with some causing millions of deaths and some far fewer. The central goal of this paper is to test an argument from previous theoretical research that high inequality within an ethnic group can make inter-ethnic conflict more violent because such inequality decreases the opportunity cost to poor group members of fighting, and also decreases the opportunity cost to rich group members of funding the conflict. To test this argument, we create a new data set that uses individual-level surveys to measure inequality within ethnic groups. The analysis using these data provide strong evidence for the importance of within-group inequality, and thus underscores the value of focusing on the capacity of groups to fight if one wishes to limit the destruction of civil conflicts. Keywords: Ethnicity, within-group inequality, civil conflict. JEL: D63, D74, J15, O15 1 This paper is a revised version of our previous work “Inequality, Ethnicity and Civil Conflict”. Huber: Depart- ment of Political Science, Columbia University, [email protected]; Mayoral: Institut d’Analisi` Economica,´ CSIC, Barcelona GSE, and University of Gothenburg; [email protected]. John Huber is grateful for financial support from the National Science Foundation (SES-0818381). Laura Mayoral gratefully acknowledges financial support from the Generalitat de Catalunya, and the Ministry of Economy and Competitiveness Grant number ECO2015-66883-P and from National Science Foundation Grant SES-1629370 (PI: Debraj Ray). We received helpful comments from Lars- Erik Cederman, Joan Esteban, Debraj Ray and seminar participants at various venues where this paper was presented. We also thank Sabine Flamand, Andrew Gianou and Tom Orgazalek for superb research assistance. 1. INTRODUCTION The tragic civil war in Syria, which broke out in 2011 and which pits a range of ethnic and sectarian groups against the government, has cost hundreds of thousands of lives and displaced millions. While it is a particularly depressing case, Syria joins a growing list of countries that have suffered from serious intrastate conflicts, which have replaced inter-state wars as the nexus for large scale violence in the world.2 Conflicts, however, vary a great deal in their intensity, with some conflicts leading to large numbers of fatalities and others to a small number. Over the period 1946-2009, for example, the total number of battle-related deaths in the 25% of least-deadly civil conflicts is less than 5,000 people in total (Lacina and Gleditsch, 2005). By contrast, the equivalent figure in the top 25% of most-deadly conflicts is close to 5 million people.3 Thus, if one wishes to limit the death and destruction of civil conflict, one must understand not simply what triggers conflict. It is perhaps even more important to focus on the factors that influence conflict severity. This paper examines empirically the relatioship between economic inequality and the severity of civil war. Previous research on economic inequality and civil war has focused on the link between inequality and grievance. This emphasis is found in long-standing arguments by Karl Marx, Dahrendorf (1959) and Gurr (1970, 1980), who argue that economic inequality breeds grievances which in turn lead to the onset of civil violence. More recent work has recognized that most civil conflict is rooted in ethnic, sectarian or other identity groups (Doyle and Sambanis 2006, Fearon and Laitin 2003), and group-level research with a focus on economic inequality has also emphasized grievances, arguing that economic inequality across groups triggers the start of civil wars (e.g., Cederman et al. 2011, Cederman et al. 2013, Cederman et al. 2015). We also focus on inequality and ethnically-based group conflict, but our analysis departs from this previous research in two substantively important respects. First, rather than focusing on inequality across groups and its link to grievances, we emphasize inequality within groups, which 2Gleditsch et al. (2002), for example, find that since WWII, there were 46 interstate conflicts with more than 25 battle- related deaths per year, 22 of which have killed at least 1,000 over the entire history of the conflict. Over the same period, there were 181 civil conflicts with more than 25 battle-related deaths per year, and almost half of them had killed more than 1,000 people. 3These figures are based on the “best estimate” of the Battle Deaths dataset, version 3.1; see Lacina and Gleditsch (2005). 3 we argue is a proxy for a group’s capacity to wage civil conflict. This requires us to measure income distributions within groups rather than economic differences across them.4 Second, we focus on the severity rather than the onset of conflict. Both of these departures from previous research are motivated by Esteban and Ray (2011), who argue that internally unequal groups – unlike groups with a large middle class composed of primarily rich or primarily poor individuals – have both the labor (poor people) and the capital (rich people) necessary to fight effectively. This focus on group capacity does not lead to clear inferences about how civil wars begin, but it does suggest that when civil conflicts occur, they will be most intense if they involve groups that have high levels of inequality among their members. Our paper makes two distinct contributions. First, we introduce a new data set that uses surveys to measure economic inequality within groups. Using survey data to this end presents important challenges which we describe below, as well as our strategies to address them. We also argue that using surveys to measure within-group inequality offers important advantages over the use of geo- coded spatial data, which have been employed in previous research. Second, we use the new data set to provide evidence of a robust association between within-group inequality and the severity of civil war (measured using battle deaths). To the best of our knowledge, this is the first paper that analyses this empirically.5 The estimated association – based on cross-national regressions which limit the possibility of making causal claims6 – is larger than the estimated effect of any other variable we examine, and it is robust. In addition, consistent with theoretical arguments emphasizing how group inequality affects the capacity rather than the incentive to fight, we find the association between within group-inequality and conflict onset to be quite weak. The paper is organized as follows. Section 2 reviews the theoretical argument about the relationship between intra-group inequality and conflict intensity. Section 3 introduces a new data 4 In a related study, Arbatli et al. (2018) find a positive relationship between conflict and within group genetic diversity,which they argue is a proxy for interpersonal diversity. We discuss how our findings and those of Arbatli et al. (2018) are related in Section 2. 5Previous studies have focused instead on conflict onset, which as noted above, is not clearly linked to the ER theory. Østby et al. (2009) find a positive association between within-region inequality and conflict onset in 22 countries in Sub-Saharan Africa, and Kuhn and Weidmann (2015), which we discuss below, find a positive association between within-group inequality and conflict onset using a global dataset that has the ethnic group – rather than the region– as unit of analysis. 6See Section 5, however, which is devoted to assessing issues of reverse causation and omitted variable bias. 4 30.46 30 26.44 22.41 20 Percent 10.34 10.34 10 0 0 <500 500-999 1,000-7,500 7,500-15,000 >15,000 Total war deaths Figure 1. Variation in the qualitative nature of civil wars set that uses individual-level surveys to measure within-group inequality. The empirical analysis is found in the three sections that follow. Section 4 focuses on conflict intensity and incidence as dependent variables, followed in Section 5 by a discussion of the possibility that results are due to omitted variable bias or reverse causality. Section 6 then turns to empirical analysis of within-group inequality and civil war onset. Section 7 concludes. Appendix A provides addi- tional analyses of the data, Appendix B provides definitions and summary statistics corresponding to the variables employed in the empirical analysis and (on-line) Appendix C contains materials regarding the data and its construction. 2. ETHNIC INEQUALITY AND CONFLICT Although empirical research on civil strife typically focuses on why conflicts break out, it is important to recognize that the damage wrought by them varies a great deal (Lacina 2006). Figure 1 summarizes some of these differences for 174 civil conflicts with battle death information in the PRIO data (see Lacina and Gleditsch 2005). Around one third of these conflicts have less than 500 total casualties, and 40% have less than 1,000. But some conflicts lead to a great deal of death, with 26% of wars having more than 15,000 casualties. Thus, limiting the devastation from civil conflicts requires that we understand the factors that can lead conflicts to become particularly severe. 5 To this end, Esteban and Ray (2011) (henceforth “ER”) provide a simply theory linking one aspect of inequality – that which exists within groups – to a group’s ability to fight, and thus to variation in conflict intensity. They argue that for a group to fight effectively, it needs financial resources and labor (i.e, fighters). Sustaining violence therefore has at least two opportunity costs: the cost of contributing resources and the cost of contributing one’s labor to fight.

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