What's in a Line? Natural Experiments and the Line of Demarcation in WWII Occupied France

In “Political Devolution and Resistance to Foreign Rule,” Ferwerda and Miller (FM) use a natural experiment during WWII France to argue that devolution of authority to local elites mitigates resistance to foreign rule. We dispute FM’s claims on four levels. First, the Line of Demarcation dividing France was delineated with the goal of keeping strategic railways under direct German control, invalidating FM’s natural experiment research design. Second, the higher level of resistance they observe in directly occupied France results from the Resistance’s efforts to target these strategic railways. Third, FM’s argument is not supported by the overall pattern of resistance in metropolitan France between 1940-44. Finally, FM’s data is unsuitable for testing theories connecting the location of an attack with its perpetrators’ precise geographic origins. These problems lead us to argue for the epistemic priority of treatment-assignment causal process observations over balance checks on pretreatment covariates when validating natural experiments.