This article has two aims: (1) to identify the causal effect of income inequality on civil conflict and (2) to find the mechanism in which disadvantaged individuals can mobilize collective violence. Applying the Heckscher-Ohlin and Stopler-Samuelson theorems, this study hypothesizes that workers in land-rich countries – those who face contracted demand in the labor market and consequently a larger income disparity – will have a lower opportunity cost to engage in conflict as trade expands. Exploiting exogenous spatial variation in inequality due to the country’s factor endowment, together with time variation in tariffs arising from the economic liberalization, the work of this research documents a statistically significant and economically meaningful causal effect of inequality on civil conflict. Secondly, to identify the mobilizing effect of inequality, I test whether higher disparity in income distribution within an ethnic group breeds more rebellions initiated by the group. Esteban and Ray’s model claims that an increase in income inequality within an ethnic group makes collective violence more likely, because the poor within the group provide conflict labor, and the rich within the group provide resources for violence. By merging international census data that cover 115 million individuals from 221 ethnic groups with the groups’ conflict records, the analysis empirically identifies that when holding total ethnic income constant, within-group inequality that is proxied by the unemployment rate is strongly correlated with the group’s propensity to initiate armed conflicts. Shedding new light on the prevailing scholarly discord that exclusively chooses either one of class and ethnic cleavages as sources of intrastate violence, the findings of this study imply that if trade-induced labor market shocks increase within-group inequality, it motivates workers to participate in rebellions by lowering their opportunity cost of fighting and mobilizes ethnic collective violence by allowing the ethnic leaders to recruit combatants at a lower cost.
This was originally published on SAGE Publications Ltd: Journal of Peace Research: Table of Contents.
