There can be no compromise: Institutional inclusiveness, fractionalization and domestic terrorism

Research on terrorism in democracies borrows from the literature on civil war and rebellion to argue that more proportional representation decreases the likelihood of terrorist violence. However, theories of broader social mobilization may be ill-suited to predicting the occurrence of terrorism. This article proposes that proportionalism's institutionalization of small minority groups as legitimate but relatively insignificant political actors leads to militancy. Analyses of the Global Terrorism Database on domestic terrorist attacks across all democracies in 1975-2007 provide broad support for this argument. The presence and greater degrees of proportionalism are significantly associated with greater levels of domestic terrorism when ethnic fractionalization within a given society increases. Moreover, domestic terrorism increases as the number of small parties represented in the legislature increases.