Punishment of any kind is to fulfill one or more of six purposes: 1) restoration, 2) retribution, 3) deterrence, 4) prevention, 5) interception, and 6) reformation.
A crime for the purposes of this article is any violation of the rights of people or any violation of morality in general.
There are three parties to consider in a punishment: the criminal, the victim (if the crime has one), and the public (everyone else in society). The fourth and unseen party is the concept of justice and morality.
A punishment is done to affect these parties in different ways for one or more of the six purposes. Almost every punishment is multifaceted, so it is not necessary any of the examples given in this article illustrate only one purpose.
1) Restoration
Restoration is when a punishment awards some benefit to the victim from the criminal to make up even if partly for the crime he committed.
Restoration is also possible without a punishment if the victim is awarded benefit that does not come from the criminal. What makes it a punishment is when the criminal is responsible for awarding the victim.
An example of this in Islamic law is the diyah (blood money) paid by a killer to the victim’s family if they forgive him from the punishment of execution.
Another example is when a person who damages some property is required to pay the price of the damages to the owner.
On the Day of Judgement, if there is a person who harmed another person and there was no justice in the world, Allah will either give the victim some good deeds from the criminal or give the criminal some bad deeds from the victim as compensation. This is also an example of restoration.
Restoration only applies to crimes with victims.
2) Retribution
Retribution (also called recompense or compensation) is when a criminal is punished to morally compensate for the crime he committed. It is not about restoration to victims. It is simply payment for a crime. This purpose relates to justice and morality itself.
It is as if the crime is the criminal taking a loan and the punishment is the repayment of the loan.
This purpose of punishment is only concerned about justice or morality in its purest essence.
It sometimes has the added effect of giving satisfaction to the victim, but that is only because humans have an inner desire for justice or moral compensation. So, the fulfillment of that moral compensation might give them satisfaction.
An example of this is when a murderer is executed for his crime of murder at the request of the victim’s family.
Another example of this is when a fornicator is punished with 100 lashes or an adulterer is punished with stoning to death. These are moral compensations for the magnitude of their crime.
The most important example of this is people being punished in Hellfire on the Day of Judgement. They are punished as moral compensation and to fulfill justice. Allah says:
That is the recompense of the enemies of Allah – the Fire. For them therein is the home of eternity as recompense for what they, of Our verses, were rejecting.
Quran 41:28
3) Deterrence
Deterrence is when a criminal is punished to discourage the public from committing the same crime. This purpose relates to the public.
It is of two types: theoretical and actual.
Theoretical deterrence is when the existence of the punishment in theory or the possibility of it in the future plays the role of deterring the public.
Actual deterrence is when the punishment is also actualized and that actualization also plays a role in deterring the public.
Almost all worldly punishments are examples of actual deterrence, like the punishments of murder, stealing, adultery, and drinking alcohol. The existence and implementation of the punishment deters people from committing the crime.
The punishment of Hellfire in the afterlife is an example of theoretical deterrence. The fact that it will occur in the future plays the role of deterring the public in this world. When it actually occurs, it will play no role of deterrence since there would be no people in tests left to deter.
The punishments of fornication and adultery can be argued to be between fully theoretical and fully practical because they are extremely difficult to implement due to the high standard of proof.
Allah’s punishment of the past nations is also an example of deterrence. It deters other nations from acting like them.
Allah explicitly describes the punishment of stealing as being for deterrence and for retribution (recompense):
[As for] the thief, the male and the female, amputate their hands in recompense for what they committed as a deterrent [punishment] from Allah. And Allah is Exalted in Might and Wise.
Quran 5:38
Allah also refers to the deterrent nature of the punishment of fornication:
The [unmarried] woman or [unmarried] man found guilty of sexual intercourse – lash each one of them with a hundred lashes, and do not be taken by pity for them in the religion of Allah, if you should believe in Allah and the Last Day. And let a group of the believers witness their punishment.
Quran 24:2
Allah requires the punishment to be in public where some people witness it. That is for deterrence.
4) Prevention
Prevention is a punishment that exists to prevent the criminal from committing a crime in the future by the punishment limiting his abilities. This and the following two purposes all relate to the criminal.
It must either be captivity, constrainment, or death since those are the only things that can accomplish that.
An example is the execution of murderers sometimes, especially serial killers. Often, murderers are not expected to be repeat offenders, so their punishment is not for prevention.
Another example is the execution or amputation of those who spread corruption in the land (like highwaymen and other violent criminals). Amputation makes them continuing to commit their crimes very difficult.
Another example is the punishment of life imprisonment non-Muslims give to murderers.
Captivity is not a punishment prescribed specifically in Islam, but it can be used by the Islamic government for some crimes as part of Tazīr, which means discretionary punishment (see article on Tazīr).
5) Interception
Interception is a punishment designed to make a criminal stop a current crime he is committing.
An example is if a person who leaves his obligatory Salah is lashed until he prays it. This would be allowed for a government to do as Tazīr (see article on Tazīr).
6) Reformation
Reformation is a punishment meant to reform a criminal to not want to commit crimes in the future.
The difference from prevention and interception is that those are punishments to stop a criminal from committing the crime by and during the punishment while reformation is to reform the criminal so that he avoids the crime even after the punishment is over.
Most (non-capital) punishments are for reformation like the punishments of stealing, fornication, slander, and drinking alcohol.
Another example is Allah punishing criminals in this world with pain and affliction.
Allah says:
And we will surely let them taste the nearer punishment short of the greater punishment that perhaps they will repent.
Quran 32:21