the nexus between socioeconomic horizontal inequalities and conflict. Section 4 presents the data and research design. Section 5 provides the results from the empirical tests. The terms of socioeconomic HIs show a positive effect on conflict onset for both the welfare indicators (household assets and education levels), and across all the three group identifiers (ethnic, religious and regional). Moreover, the results indicate that this effect is influenced by regime type. The conflict potential of HIs seems to be stronger in democracies and semi-democracies than in autocracies. I also find some evidence that not only the level of democracy, but also the institutional setup within the democracies may be of importance here. Although the results are not very robust across various indicators of social welfare (household assets and education), the trend seems to be that the positive effect of socioeconomic horizontal inequalities on civil war increases with the level of inclusiveness of the electoral system. Finally, although direct political exclusion shows no separate effect on conflict, it seems strongly to enforce the positive relationship between regional HIs and conflict. The last section concludes.

# **2 Horizontal Inequalities and Civil Conflict**

Stewart (2002: 1) defines horizontal inequalities as ‘systematic inequalities between culturally formed groups’, such as ethnic, religious or regional groups. Systematic, socioeconomic inequalities between identity groups often have their origin in historical circumstances, such as colonial policies, which privileged some groups over others. Sometimes, however, horizontal inequalities are not caused by deliberate agency at all but simply become evident for example when traditional peoples on the periphery of modernizing societies are drawn into closer contact with more powerful and technologically proficient groups (Gurr, 2000).<sup>3</sup> An initial advantage often leads to long-term cumulative advantages, as resources and education allow the more privileged groups to secure further advantages. Likewise, group deprivation tends to be reproduced over time, like in South Africa – even after apartheid (see e.g. World Bank, 2006: 1).

A shared cultural identity may be a powerful organizing principle for a group. First of all, it overcomes the collective action problem (Olson, 1965) whereby people are unable to cooperate because of mutual suspicions. However, there is reason to believe that a shared identity is not a sufficient factor to produce conflict. In line with this, Murshed & Gates (2005) argue that some well-defined grievances are required for identity-based conflict.

Given that groups are the central units in conflicts the question then is how they are mobilized. Stewart (2000) shows how different identity bases have been the source of group differentiation and mobilization: In central Africa, ethnicity has been the major basis of group categorization; in Central America, group identification and organization has developed along social class lines, with some overlapping ethnic dimensions; and in the Balkans and Northern Ireland religion has been the primary feature of categorization. However, regional location is a source of group differentiation, which often coincides with ethnic or linguistic cleavages, like for

> 3 Without analyzing each country in depth it is hard to tell whether group inequalities predate repression or not. Furthermore, objective measures of group inequalities do not necessarily perfectly reflect people’s perceptions of such inequalities. An ongoing project at Centre for Research on Inequality Ethnicity and Human Security (CRISE) at the University of Oxford, involves mapping people’s perceptions of group inequalities in eight countries based on particular perception surveys. This seems as a promising start for studying the degree to which people’s grievances correspond with objective group inequalities in society.

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