Horizontal inequality and armed conflict: a comprehensive literature review

The review finds strong empirical support for the argument that high levels of group-based economic and political deprivation increase the likelihood of armed conflict, particularly when combined with political exclusion. While economic deprivation is a consistent driver, the role of relative privilege is less clear. The authors highlight significant knowledge gaps regarding social horizontal inequalities, within-group inequality, and the mediating role of perceptions. Methodologically, the paper notes challenges with data quality and endogeneity, suggesting that while the inequality-conflict relationship generally holds under instrumental variable analysis, more granular, individual-level, and non-ethnic group studies are required.

• There is strong empirical evidence that high levels of economic and political deprivation among ethnic groups increase the likelihood of armed conflict.
• Economic horizontal inequality is more strongly linked to conflict when it occurs alongside political exclusion, as this provides leaders with incentives to challenge the status quo.
• Research indicates that relative economic deprivation is a more consistent driver of conflict than relative privilege, for which results remain inconclusive.
• Political horizontal inequality, specifically exclusion from executive power or a recent loss of such power, is positively associated with the risk of group participation in armed conflict.
• Objective inequality does not automatically lead to conflict because the translation to perceived inequality is subject to manipulation and misperception.
• The presence of natural resource wealth, particularly oil, enhances the conflict potential associated with political exclusion.
• Addressing endogeneity through instrumental variable analysis generally confirms the inequality-conflict relationship and suggests that governments may preemptively include conflict-prone groups in government to prevent revolt.

APA

Hillesund, S., Bahgat, K., Barrett, G., Dupuy, K., Gates, S., Nygård, H. M., Rustad, S. A., Strand, H., Urdal, H., & Østby, G. (n.d.). Horizontal inequality and armed conflict: a comprehensive literature review. Peace Research Institute Oslo. https://cdn.cloud.prio.org/files/a26a32e7-7908-4c8d-9dce-72724133e3db/Horizontal inequality and armed conflict a comprehensive literature review.pdf?inline=true

Chicago

Hillesund, Solveig, Karim Bahgat, Gray Barrett, Kendra Dupuy, Scott Gates, Håvard Mokleiv Nygård, Siri Aas Rustad, et al. Horizontal inequality and armed conflict: a comprehensive literature review. Peace Research Institute Oslo, n.d. https://cdn.cloud.prio.org/files/a26a32e7-7908-4c8d-9dce-72724133e3db/Horizontal inequality and armed conflict a comprehensive literature review.pdf?inline=true.

Wikipedia

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BibTeX

@techreport{hillesundndhorizontal, author = {Hillesund, Solveig and Bahgat, Karim and Barrett, Gray and Dupuy, Kendra and Gates, Scott and Nygård, Håvard Mokleiv and Rustad, Siri Aas and Strand, Håvard and Urdal, Henrik and Østby, Gudrun}, title = {{Horizontal inequality and armed conflict: a comprehensive literature review}}, institution = {Peace Research Institute Oslo}, url = {https://cdn.cloud.prio.org/files/a26a32e7-7908-4c8d-9dce-72724133e3db/Horizontal inequality and armed conflict a comprehensive literature review.pdf?inline=true}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }