Model Uncertainty and the Deterrent Effect of Capital Punishment

The reintroduction of capital punishment in 1976 that ended the four-year moratorium on executions generated by the Supreme Court in the 1972 decision Furman v. Georgia has permitted researchers to employ state-level heterogeneity in the use of capital punishment to study deterrent effects. However, no scholarly consensus exists as to their magnitude. A key reason that this has occurred is that the use of alternative models across studies produces differing estimates of the deterrent effect. Because differences across models are not well motivated by theory, the deterrence literature is plagued by model uncertainty. We argue that the analysis of deterrent effects should explicitly recognize the presence of model uncertainty in drawing inferences. We describe methods for addressing model uncertainty and apply them to understand the disparate findings between two major studies in the deterrence literature, finding that evidence of deterrent effects appears, while not nonexistent, weak.