The authors begin the construction of a generalizable theory of casual
ties and opinion, reexamining the logic employed by Mueller and showin
g that although human costs are an important predictor of wartime opin
ion, Mueller's operationalization of those costs solely as the log of
cumulative national casualties is problematic and incomplete. The auth
ors argue that temporally proximate costs, captured as marginal casual
ty figures, are an important additional aspect of human costs and a cr
itical factor in determining wartime opinion. Using Mueller's data on
opinion in the Vietnam and Korean wars, the authors find that marginal
casualties are important in explaining opinion when casualty accumula
tion is accelerating, and earlier findings about the importance and ge
neralizability of the log of cumulative casualties as the sole casualt
y-based predictor of opinion are overstated. Finally, the authors offe
r some thoughts about other factors that should be considered when bui
lding a model of war deaths and domestic opinion.