The Multiple Effects of Casualties on Public Support for War: An Experimental Approach

Public support for a conflict is not a blank check. Combat provides information people use to update their expectations about the outcome, direction, value, and cost of a war. Critical are fatalities—the most salient costs of conflict. I develop a rational expectations theory in which both increasing recent casualties and rising casualty trends lead to decreased support. Traditional studies neither recognize nor provide a method for untangling these multiple influences. I conduct six experiments, three on the Iraq War (two with national, representative samples) and three with a new type of panel experiment design on hypothetical military interventions. The results of hazard and ordered logit analyses of almost 3,000 subjects support a rational expectations theory linking recent casualties, casualty trends, and their interaction to wartime approval. I also examine the effects of the probability of victory, information levels, and individual characteristics on the support for war, and contrast results from representative and convenience samples.