Death Penalty as Deterrent: Arguments For Capital Punishment

Introduction: The Deterrence Question

If it is difficult — perhaps impossible — to prove statistically, and just as hard to disprove, that the death penalty deters more from capital crimes than available alternative punishments such as life imprisonment, why do so many people believe so firmly that the death penalty is a more effective deterrent?

Some are persuaded by irrelevant arguments. They insist that the death penalty at least ensures that the person who suffered it will not commit other crimes. True — yet this confuses incapacitation with one particular way of achieving it: death. Death is the surest way to bring about total incapacitation, and it is irrevocable. But does incapacitation need to be that total? And is irrevocability necessarily an advantage? Obviously, it makes correcting mistakes and rehabilitation impossible. What, then, is the advantage of execution over alternative ways of achieving the desired incapacitation? More importantly, the argument for incapacitation confuses the elimination of one murderer — or of any number of murderers — with a reduction in the homicide rate. The elimination of any specific number of actual or even potential murderers will not affect the homicide rate, except through deterrence. There are enough potential murderers to replace all those incapacitated. Deterrence may prevent the potential from becoming actual murderers, but incapacitation of some or all actual murderers is not likely to have much effect by itself. The question remains: does capital punishment deter more than life imprisonment?

Science, logic, or statistics have often been unable to prove what common sense tells us to be true. The Greek philosopher Zeno, roughly 2,000 years ago, found that he could not demonstrate that motion is possible; indeed, his famous paradoxes appear to show that motion is impossible. Though nobody believed them to be true, nobody succeeded in exposing the fallacy of those paradoxes until the rise of mathematical logic less than a hundred years ago. Yet the world did not stand still in the interim. Nobody argued that motion should stop because it had not been shown to be logically possible. There is no more reason to abolish the death penalty than there was to abolish motion simply because the death penalty has not been — and perhaps cannot be — shown statistically to be a deterrent over and above other penalties. There are, in fact, two quite satisfactory, if non-statistical, indications of the marginal deterrent effect of the death penalty.

Once a punishment exceeds, say, ten years in prison (net of parole), there may be little additional deterrence gained by threatening additional years. We know very little about diminishing returns in the area of criminal penalties. It still seems likely, however, that the threat of life in prison deters more than any shorter term of imprisonment, and the threat of death may deter still more. It is a mistake to regard the death penalty as though it were merely another point on the same continuum of penalties. Death differs significantly, in kind, from any other punishment. Life in prison is still life, however unpleasant. The death penalty, by contrast, does not merely threaten to make life unpleasant — it threatens to take life altogether. This difference is perceived by those most directly affected. When prisoners under sentence of death are given the choice between life in prison and execution, 99% prefer life in prison. Through appeals, pleas for commutation, and every other available means, they demonstrate that they prefer life in prison to execution.

From this unquestioned fact, a reasonable conclusion can be drawn in favor of the superior deterrent effect of the death penalty. Those who have the choice in practice — those whose choice has actual and immediate effects on their own survival — fear death more than they fear life in prison or any other available penalty. If they do, it follows that the threat of the death penalty, all other things being equal, is likely to deter more than the threat of life in prison. One is most deterred by what one fears most.

Suppose one is not fully convinced of the superior deterrent effect of the death penalty. Even if one is genuinely uncertain whether the death penalty adds to deterrence, one should still favor it from a purely deterrent viewpoint. If we are uncertain, we must choose between two alternatives: (1) trading the certain death, by execution, of a convicted murderer for the probable survival of an indefinite number of future murder victims — whose survival becomes more likely if the convicted murderer's execution deters prospective murderers — or (2) trading the certain survival of the convicted murderer for the probable loss of the lives of future murder victims, who are more likely to be killed because the convicted murderer's non-execution failed to deter prospective murderers who might have been deterred by an execution.

To restate the matter: if we were entirely ignorant about the marginal deterrent effects of execution, we would have to choose between the certainty of the convicted murderer's death by execution and the likelihood of the survival of future victims on the one hand, and on the other his certain survival and the likelihood of the deaths of new victims. The preferable choice is to execute a person convicted of murdering others rather than to put the lives of innocents at risk.

Incapacitation and Its Limits

Those who insist that the death penalty has not been demonstrated to be more deterrent than other penalties may not genuinely believe that it is not, or that deterrence even matters. The deterrent effect of the death penalty — or its absence — does not appear to be what actually drives abolitionist opposition. Rather, the lack of statistical demonstration of a marginal deterrent effect is used to rationalize opposition that has other, non-rational sources. In fact, most abolitionists are not entirely serious about the relevance of their own argument from insufficient deterrence.

Perhaps the most straightforward argument for the death penalty is that it saves innocent lives by preventing convicted murderers from killing again. To understand the risk posed by abolition, consider the following data: of 52,000 state prison inmates in 1984 serving time on murder charges, approximately 810 were convicted felons who had previously been convicted of murder, and together they had killed 821 persons after those prior convictions (U.S. Department of Justice, 1999). Executing each of these inmates after the first murder conviction would have saved the lives of more than 800 persons.

Abolitionists respond to this argument by observing that only a fraction of murderers receive the death penalty. Bedau argues that "the only way to [completely] prevent such recidivism would be to execute every murderer, a policy that is politically unavailable and morally indefensible" (Bedau & Radelet, 1987). This response is unsatisfying. It is no indictment of death penalty procedures to learn that they do not single-mindedly pursue the goal of incapacitating murderers. The American death penalty responds to a variety of concerns, including not only incapacitation but also the possibility of rehabilitation and mercy. No other criminal justice sanction makes the prevention of recidivism its exclusive goal. Society sentences most criminals to a term of years rather than to life, reserving the life sentence for the worst offenders. Yet no one argues that recidivism is inappropriately addressed through life imprisonment merely because such sentences are reserved for circumstances where, in light of all relevant factors, they are most appropriate.

Deterrence: Logic, Evidence, and Theory

The death penalty's incapacitative benefits come from preventing the individual murderers who are apprehended and executed from killing again — what criminologists call specific deterrence. More significant benefits come from the death penalty's restraining effect on the much larger pool of potential murderers, what criminologists call general deterrence. Evidence for capital punishment's general deterrent effect comes from three sources: logic, firsthand reports, and social science research.

Logic supports the conclusion that the death penalty is an effective deterrent for serious crimes including murder. As James Q. Wilson has explained: "People are governed in their daily lives by rewards and penalties of every sort. We shop for bargain prices, praise our children for good behavior and scold them for bad, expect lower interest rates to stimulate home building and fear that higher ones will depress it, and conduct ourselves in public in ways that lead our friends and neighbors to form good opinions of us. To assert that 'deterrence doesn't work' is tantamount to either denying the plainest facts of everyday life or claiming that would-be criminals are utterly different from the rest of us" (Wilson, 1983).

Whenever society faces a problem with a burgeoning number of crimes — be it kidnappings in the 1930s, aircraft hijackings in the 1970s, domestic violence in the 1980s, or political terrorism in the 2000s — the public response is almost invariably to increase the criminal penalties associated with those crimes. We take it as uncontroversial that increased penalties will deter at least some prospective criminals, making the increased penalty worthwhile. Our entire criminal justice system is premised on the belief that increasing penalties increases deterrence.

The logic of deterrence applies to aggravated homicides no less than to other crimes. As the Supreme Court observed in Gregg v. Georgia (1976): "There are carefully contemplated murders, such as the murder for hire, where the possible penalty of death may well enter into the cold calculus that precedes the decision to act." The death penalty applies only to "carefully contemplated" first-degree murders — that is, murders committed with premeditation and malice. It is no answer to the deterrence argument to say that the death penalty cannot prevent a killing during a barroom brawl; such heat-of-passion offenses are typically punished as second-degree murders and are not eligible for capital punishment. The ultimate penalty is reserved for first-degree murders and, indeed, for a subset of especially aggravated first-degree murders. Nor is it an answer to say that murders continue to be committed despite the death penalty. The salient issue is not whether the death penalty deters every murder, only whether it deters some. Logic suggests that at least some potential murderers will be deterred.

Conclusion and Recommendations

Abolitionists such as Stephen Nathanson argue that because the statistical evidence in favor of the deterrent effect of capital punishment is indecisive, we have no basis for concluding that it is a better deterrent than long prison sentences (Nathanson, 2001). If I understand these opponents correctly, their argument presents an exclusive disjunction: either we must have conclusive statistical evidence — a proof — for the deterrent effect of the death penalty, or we have no grounds for supposing that the death penalty deters at all. Many people accept this argument.

There is, however, a middle position: while we cannot prove conclusively that the death penalty deters, the weight of evidence supports its deterrence. Furthermore, there are too many variables to hold constant for us to prove the deterrence hypothesis through statistics alone, and even if the requisite data were available, we might reasonably question whether we were observing mere correlation rather than causation. On the other hand, commonsense and anecdotal evidence can provide genuine insight into the psychology of human motivation, offering evidence that fear of the death penalty does deter some would-be murderers from committing homicide.

In contrast to the general declines in homicide rates seen in leading death penalty states, the largest abolitionist states have seen rising homicide rates. Among non-death penalty states large enough to have two congressional representatives and without wild swings in annual murder rates, the following pattern emerges: of Wisconsin, Minnesota, Massachusetts, Iowa, Michigan, West Virginia, Rhode Island, and Hawaii, six have seen their murder rates rise since 1966 (Wisconsin, Minnesota, Michigan, West Virginia, Rhode Island, and Hawaii), one has stayed the same (Maine), and two have seen slight reductions (Massachusetts by 0.4 percentage points and Iowa by a comparable margin) (U.S. Department of Justice, Bureau of Justice Statistics, 1999).

These state-by-state comparisons are bolstered by more sophisticated and recent econometric analyses that control for the variety of demographic, economic, and other variables that differ among states. The best of these studies suggest that the death penalty has an incremental deterrent effect over imprisonment — in plainer terms, that the death penalty saves innocent lives.

Research has shown that the majority of Americans do not consider the death penalty cruel. According to polls, approximately 70% of Americans favor the death penalty (U.S. Department of Justice, Bureau of Justice Statistics, 1999). When the Supreme Court objected to certain aspects of state laws imposing capital punishment, more than two-thirds of all states reenacted them so as to remove the putative constitutional defects. This does not, in itself, show that the death penalty is a good thing — but it does show that the majority of Americans and their state representatives favor it. If the majority in any state does not want the death penalty, it can abolish it, and in the past often has. Why, then, make it a federal or constitutional matter? Why make the retention or abolition of capital punishment a judicial matter at all?