The purposes of criminal punishment are rather unanimously delineated in the Catholic tradition. Punishment is held to have a variety of ends that may conveniently be reduced to the following four: rehabilitation, defense against the criminal, deterrence, and retribution. Granted that punishment has these four aims, we may now inquire whether the death penalty is the apt or necessary means to attain them.
Rehabilitation. Capital punishment does not reintegrate the criminal into society; rather, it cuts off any possible rehabilitation. The sentence of death, however, can and sometimes does move the condemned person to repentance and conversion. There is a large body of Christian literature on the value of prayers and pastoral ministry for convicts on death row or on the scaffold. In cases where the criminal seems incapable of being reintegrated into human society, the death penalty may be a way of achieving the criminal’s reconciliation with God.
Defense against the criminal. Capital punishment is obviously an effective way of preventing the wrongdoer from committing future crimes and protecting society from him. Whether execution is necessary is another question. One could no doubt imagine an extreme case in which the very fact that a criminal is alive constituted a threat that he might be released or escape and do further harm. But, as John Paul II remarks in Evangelium Vitae , modern improvements in the penal system have made it extremely rare for execution to be the only effective means of defending society against the criminal.
Deterrence. Executions, especially where they are painful, humiliating, and public, may create a sense of horror that would prevent others from being tempted to commit similar crimes. But the Fathers of the Church censured spectacles of violence such as those conducted at the Roman Colosseum. Vatican II’s Pastoral Constitution on the Church in the Modern World explicitly disapproved of mutilation and torture as offensive to human dignity. In our day death is usually administered in private by relatively painless means, such as injections of drugs, and to that extent it may be less effective as a deterrent. Sociological evidence on the deterrent effect of the death penalty as currently practiced is ambiguous, conflicting, and far from probative.
Retribution. In principle, guilt calls for punishment. The graver the offense, the more severe the punishment ought to be. In Holy Scripture, as we have seen, death is regarded as the appropriate punishment for serious transgressions. Thomas Aquinas held that sin calls for the deprivation of some good, such as, in serious cases, the good of temporal or even eternal life. By consenting to the punishment of death, the wrongdoer is placed in a position to expiate his evil deeds and escape punishment in the next life. After noting this, St. Thomas adds that even if the malefactor is not repentant, he is benefited by being prevented from committing more sins. Retribution by the State has its limits because the State, unlike God, enjoys neither omniscience nor omnipotence. According to Christian faith, God “will render to every man according to his works” at the final judgment (Romans 2:6; cf. Matthew 16:27). Retribution by the State can only be a symbolic anticipation of God’s perfect justice.
For the symbolism to be authentic, the society must believe in the existence of a transcendent order of justice, which the State has an obligation to protect. This has been true in the past, but in our day the State is generally viewed simply as an instrument of the will of the governed. In this modern perspective, the death penalty expresses not the divine judgment on objective evil but rather the collective anger of the group. The retributive goal of punishment is misconstrued as a self-assertive act of vengeance.
The death penalty, we may conclude, has different values in relation to each of the four ends of punishment. It does not rehabilitate the criminal but may be an occasion for bringing about salutary repentance. It is an effective but rarely, if ever, a necessary means of defending society against the criminal. Whether it serves to deter others from similar crimes is a disputed question, difficult to settle. Its retributive value is impaired by lack of clarity about the role of the State. In general, then, capital punishment has some limited value but its necessity is open to doubt.
Avery Cardinal Dulles, “Catholicism & Capital Punishment” (2001)