Is There More Violence in the Middle?

Is there more violence in the middle? Over 100 studies have analyzed whether violent outcomes such as civil war, terrorism, and repression are more common in regimes that are neither full autocracies nor full democracies, yet findings are inconclusive. While this hypothesis is ultimately about functional form, existing work uses models in which a particular functional form is assumed. Existing work also uses arbitrary operationalizations of “the middle. ” This article aims to resolve the empirical uncertainty about this relationship by using a research design that overcomes the limitations of existing work. We use a random forest-like ensemble of multivariate regression and classification trees to predict multiple forms of conflict. Our results indicate the specific conditions under which there is or is not more violence in the middle. We find the most consistent support for the hypothesis with respect to minor civil conflict and no support with respect to repression. Replication Materials: The data, code, and any additional materials required to replicate all analyses in this article are available on the American Journal of Political Science Dataverse within the Harvard Dataverse Network, at: https://doi.org/10.7910/DVN/LNUYXZ. What is the relationship between regime type and political violence? Are certain forms of conflict more likely in democracies or in autocracies? A series of influential studies has suggested this relationship is curvilinear, with violence most likely in regimes in the middle range—often referred to as anocracies—that are neither fully autocratic nor fully democratic (Eck and Hultman 2007; Fein 1995; Hegre et al. 2001). We refer to these arguments, collectively, as the More Violence in the Middle Hypothesis (or MVM Hypothesis). Despite decades of research, the extent to which such theories are empirically supported is unclear. While some early studies found that civil wars are most likely in anocracies (Hegre et al. 2001), others did not (Sambanis 2001). The debate may have appeared resolved when Vreeland (2008) showed that correcting for the extent to which measures of democracy might include indicators of violence results in no support for the MVM Hypothesis, but since then some have used his measure and found support for the hypothesis (Gleditsch and Ruggeri 2010), whereas others have confirmed his result (Peic and Reiter 2011). Likewise, some find evidence that terrorism is most Zachary M. Jones is Postdoctoral Fellow, eScience Institute, Campus Box 351570, University of Washington, Seattle, WA 98195-1570 (zmj@zmjones.com). Yonatan Lupu is Assistant Professor, Department of Political Science, George Washington University, Monroe Hall, Room 417, 2115 G Street, NW, Washington, DC 20052 (ylupu@gwu.edu). For comments on previous drafts, we thank Erica Chenoweth, Christian Davenport, Scott Gates, Will Moore, and Jake Shapiro, as well as participants in workshops at New York University, Uppsala University, and George Washington University. For research assistance, we thank Jack Hasler, Bryce Loidolt, and Steven Schaaf. common in anocracies (Wade and Reiter 2007), whereas others do not (Chenoweth 2010). With respect to repression, Davenport and Armstrong (2004) arguably settled the question by using more appropriate methods for testing this hypothesis than the bulk of the literature and finding no support for the MVM Hypothesis, but some recent work continues to find support for it (Mitchell, Ring, and Spellman 2013). The purpose of this article is to reduce the empirical uncertainty about the MVM Hypothesis and describe the conditions under which it does or does not hold. Although existing work has made significant progress, the methods used to date have several consequential limitations. The MVM Hypothesis is a prediction about the functional form of the relationship between regime type and conflict, yet almost all existing tests of the MVM Hypothesis have been conducted using models that assume a particular functional form and then test whether the data allow us to reject a simpler possible relationship between regime type and conflict, such as a monotonic relationship. While such tools can allow us to reject a monotonic relationship, they are not well suited for understanding the more complex ways in which regime type American Journal of Political Science, Vol. 62, No. 3, July 2018, Pp. 652–667 C ©2018, Midwest Political Science Association DOI: 10.1111/ajps.12373