On the Death Penalty

Ethical, philosophical and religious values are central to the continuing controversy over capital punishment. Nevertheless, factual evidence can and should inform policy making. The evidence for capital punishment as an uniquely effective deterrent to murder is especially important, since deterrence is the only major pragmatic argument on the pro-death penalty side.1 The purpose of this paper is to survey and evaluate the evidence for deterrence. We must define the question correctly. We are not asking whether the threat of punishment, in general, deters crime, nor whether there should be heavy penalties for murder. The issue at stake is this: Does capital punishment, in a form which has been or might be practiced in the United States, provide a better deterrent to murder than long imprisonment? In particular, is it likely that expanding the death penalty in New Hampshire will lead to fewer murders? If not, capital punishment offers no practical benefits to weigh against its social costs.2
1 It is often suggested that executing convicted murderers can at least save money. This common belief is wrong; executions are far more expensive than life imprisonment. See Mark Costanzo and
Lawrence White, "An overview of the death penalty and capital trials: history, current status, legal procedures, and cost," Journal of Social Issues 50, no. 2 (summer 1994), pp, 1-18.
2
The greatest cost is that innocent people have been executed, and that others surely will be in theA small (but still substantial) portion of the vast literature on crime and prevention deals with factual evidence about deterrence. This evidence is statistical and the problems of interpretation are difficult. Nevertheless, there is a broad consensus about the answer to our question. We will begin the survey after some general remarks about statistical reasoning.
Two examples of statistical evidence
Statistical analysis is essential for interpreting complex data and making