One is most deterred by what one fears most. From which it follows that whatever statistics fail, or do not fail, to show, the death penalty is likely to be more deterrent than any other.
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 do (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 makes sure that the person who suffered it will not commit other crimes. True. Yet this confuses incapacitation with a specific way to bring it about: death. Death is the surest way to bring about the most 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 is the advantage of execution, then, over alternative ways of achieving the desired incapacitation? More important, the argument for incapacitation confuses the elimination of one murderer (or of any number of murderers) with a reduction in the homicide rate. But the elimination of any specific number of actual or even of potential murderers, and there is some doubt that the actual murderers of the past are the most likely future (potential) murderers, will not affect the homicide rate, except through deterrence. There are enough potential murderers around 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. Let us then return to the question: Does capital punishment deter more than life imprisonment?
Science, logic, or statistics often have been unable to prove what common sense tells us to be true. Thus, the Greek philosopher Zeno some 2000 years ago found that he could not show 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 showing the fallacy of these paradoxes until the rise of mathematical logic less than a hundred years ago. But meanwhile, the world did not stand still. Indeed, 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. Indeed, there are two quite satisfactory, if non-statistical, indications of the marginal deterrent effect of the death penalty.
Once a punishment exceeds, say, 10 years in prison (net of parole), there may be little additional deterrence in threatening additional years. We know hardly anything about diminishing returns of penalties. It would still seem likely, however, that the threat of life in prison deters more than any other term of imprisonment. The threat of death may deter still more. For it is a mistake to regard the death penalty as though it were of the same kind as other penalties. If it is not, then diminishing returns are unlikely to apply. And death differs significantly, in kind, from any other penalty. Life in prison is still life, however unpleasant. In contrast, the death penalty does not just threaten to make life unpleasant, it threatens to take life altogether. This difference is perceived by those affected. We find that when they have the choice between life in prison and execution, 99% of all prisoners under sentence of death prefer life in prison. By means of appeals, pleas for commutation, indeed by all means at their disposal, they indicate 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 life and death, 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 equal, is likely to deter more than the threat of life in prison. One is most deterred by what one fears most. From which it follows that whatever statistics fail, or do not fail, to show, the death penalty is likely to be more deterrent than any other. Suppose now one is not fully convinced of the superior deterrent effect of the death penalty. I believe I can show that even if one is genuinely uncertain as to whether the death penalty adds to deterrence, one should still favor it, from a purely deterrent viewpoint. For if we are not sure, we must choose either to (1) trade the certain death, by execution, of a convicted murderer for the probable survival of an indefinite number of murder victims whose future murder is less likely (whose survival is more likely), if the convicted murderer's execution deters prospective murderers, as it might, or to (2) trade the certain survival of the convicted murderer for the probable loss of the lives of future murder victims more likely to be murdered because the convicted murderer's non-execution might not deter prospective murderers, who could have been deterred by executing the convicted murderer.
To restate the matter: If we were quite ignorant about the marginal deterrent effects of execution, we would have to choose, like it or not, between the certainty of the convicted murderer's death by execution and the likelihood of the survival of future victims of other murderers on the one hand, and on the other his certain survival and the likelihood of the death of new victims. I'd rather execute a man convicted of having murdered others than to put the lives of innocents at risk. I find it hard to understand the opposite choice.
However, I doubt that those who insist that the death penalty has not been demonstrated to be more deterrent than other penalties really believe that it is not. Or that it matters. I am fairly certain that the deterrent effect of the death penalty, or its absence, is not actually important to them. Rather, I think, they use the lack of statistical demonstration of a marginal deterrent effect to rationalize an opposition to the death penalty that has nonrational sources yet to be examined. In fact, although they use the alleged inconclusiveness of statistical demonstrations of deterrence as an argument to dissuade others from the death penalty, it can be shown that most abolitionists are not quite serious about the relevance of their own argument from insufficient deterrence.
The death penalty poses a legal as well as a moral question. Thus, many lawyers in the United States have tried to get the Supreme Court to declare capital punishment unconstitutional mainly on the basis of the Eighth Amendment, which prohibits "cruel and unusual punishment," or of the Fourteenth, which requires "the equal protection of the laws" for all the inhabitants of the United States. Let us consider the constitutional question then. The Eighth Amendment, which prohibits "cruel and unusual punishment" was enacted in 1791. However, so was the Fifth Amendment, which requires that no one shall be "deprived of life, liberty or property without due process of law." The Fifth Amendment implies that with "due process of law" one may be deprived "of life, liberty or property," i.e., that the death penalty is a legitimate punishment. Since the prohibition of "cruel and unusual punishment" was enacted at the same time, obviously it was not meant to repeal the death penalty, which at the time was imposed frequently.
If the framers did not consider the death penalty "cruel and unusual," do we? If we do, is what we consider "cruel and unusual" today to determine whether laws imposing the death penalty are constitutional, or should we be guided by what the framers of the Constitution meant by "cruel and unusual"? If we are to be guided by what they thought, the Constitution binds us until it is amended, and the death penalty is constitutional. * If we are to be guided by what we want and not by what the framers of the Constitution decided, why have a Constitution? Why pretend to adhere to a rule made in the past when we mean to be bound only by the rules we make? To have a Constitution means to wish to adhere to rules made in the past. Else we can leave everything to the rules we currently decide on.
If standards of cruelty did evolve, so that what was not thought "cruel and unusual" when the Fifth and Eighth Amendments were passed now is perceived to be, should the death penalty become unconstitutional? One first must ask: Perceived by whom? The people? If…