The democratic peace - the idea that
democracies rarely fight one another - has been called "the
closest thing we have to an empirical law in the study of
international relations." Yet, some contend that this
relationship is spurious and suggest alternative
explanations. Unfortunately, in the absence of randomized
experiments, we can never rule out the possible existence of
such confounding biases. Rather than commonly used
regression-based approaches, we apply a nonparametric
sensitivity analysis. We show that overturning the negative
association between democracy and conflict would require a
confounder that is forty-seven times more prevalent in
democratic dyads than in other dyads. To put this number in
context, the relationship between democracy and peace is at
least five times as robust as that between smoking and lung
cancer. To explain away the democratic peace, therefore,
scholars would have to find far more powerful confounders than
those already identified in the literature. |