Supplementary Appendix: Do Democracies Possess the Wisdom of Crowds? Decision Group Size, Regime Type, and Strategic Effectiveness

What is it about democracies—if anything—that enables them to avoid war with each other while navigating conflictual international politics in pursuit of their own interests? Recent research in International Studies Quarterly by Brad LeVeck and Neil Narang (2017) provides an elegant new answer to this longstanding question. Drawing on “wisdom of crowds” logic—the insight that a large-enough group of inexpert judges is more likely to average towards an accurate estimate of a continuous variable than a smaller group, even when the smaller group contains relevant experts—supported by experimental evidence, they suggest that democracies’ strategic advantages lie in their large, diverse decision-making communities. If such crowd wisdom equips democracies to accurately assess others’ capabilities and intentions, so the argument goes, then they should be better than alternative regime types at maximizing their own interests while still avoiding the bargaining failure that is resort to war. Unfortunately, however, the politics of democratic foreign policy-making compromise the crowd-wisdom mechanism. This response article thus elucidates key flaws in the argument that crowd wisdom underpins democratic peace, before progressing to explain how the crowd-wisdom insight nonetheless carries important implications—irrespective of regime type—for strategic effectiveness.