Deterrence
Can fear discourage crime? There has been much debate over whether deterrence works. Proponents assert that punishment deters if it is administered with celerity (swiftness), certainty, and severity. A distinction needs to be drawn between general versus specific deterrence. General deterrence uses the person sentenced for a crime as an example to induce the public to refrain from criminal conduct, while specific deterrence punishes an offender to dissuade that offender from committing crimes in the future. Critics point to the high recidivism (relapse into crime) rates of persons sentenced to prison as evidence of the lack of effectiveness of specific deterrence. Critics also note that there are limits to the impact of general deterrence. Some crimes, such as crimes of passion and crimes committed while under the influence of drugs, can't be deterred because their perpetrators don't rationally weigh the benefits versus the costs (which include punishment) before breaking the law. Finally, research evidence suggests that the deterrent effect of punishment is weak.
Incapacitation
A popular reason for punishment is that it gets criminals off the streets and protects the public. The idea is to remove an offender from society, making it physically impossible (or at least very difficult) for him or her to commit further crimes against the public while serving a sentence. Incapacitation works as long as the offenders remain locked up. There is no question that incapacitation reduces crime rates by some unknown degree. The problem is that it is very expensive. Incapacitation carries high costs not only in terms of building and operating prisons, but also in terms of disrupting families when family members are locked up.
Rehabilitation
“Let the punishment fit the criminal” expresses the rehabilitative ethic. Rehabilitation calls for changing the individual lawbreaker through correctional interventions, such as drug‐treatment programs.
Common ground
But evaluations of correctional treatment show it doesn't consistently prevent or reduce crime. Why has rehabilitation failed? Funding has been inadequate, so the full effectiveness of rehabilitation hasn't been tested. Furthermore, certain criminals—such as perpetrators of nonviolent crimes and first‐time offenders—are more likely to be successfully rehabilitated than repeat offenders and violent criminals.
Deterrence, incapacitation, and rehabilitation are all arguments that look to the consequences of punishment. They are all forward‐looking theories of punishment. That is, they look to the future in deciding what to do in the present. The shared goal of all three is crime prevention.
Retribution
“Let the punishment fit the crime” captures the essence of retribution. Proponents advocate just deserts, which defines justice in terms of fairness and proportionality. Retributivists aim to dispense punishment according to an offender's moral blameworthiness (as measured by the severity of crimes of which the offender was convicted). Ideally, the harshness of punishments should be proportionate to the seriousness of crimes. In reality, it is difficult to match punishments and crimes, since there is no way to objectively calibrate the moral depravity of particular crimes and/or the painfulness of specific punishments. Retribution is a backward‐looking theory of punishment. It looks to the past to determine what to do in the present.