Kant's Retributivism

In one line

Kant says punishment is owed to the guilty because they are guilty, that it may never be inflicted as a means of producing some benefit, and that the measure of it is what the offender did.

In the wording a student can write in an exam: Kant holds that juridical punishment can never be administered merely as a means of promoting another good, whether for the criminal himself or for civil society, but must in all cases be imposed only because the individual on whom it is inflicted has committed a crime; that the principle of equality determines both the quality and the quantity of punishment, which he calls the right of retaliation or ius talionis; and that this is the only principle which, in regulating a public court as distinguished from private judgment, can definitely assign the kind and degree of punishment.

The moral foundation

Kant's theory of punishment is not a separate doctrine bolted on to his ethics. It follows from two propositions that run through everything he wrote.

A person must never be treated merely as a means. Human beings possess dignity, which is a worth beyond price, and to use a person as an instrument for producing some result is to deny that worth. This is why the utilitarian theory of the next chapter is, for Kant, not merely mistaken but a wrong done to the person punished.

Punishment must be deserved, and desert is backward looking. The question is what the offender did, not what will follow from punishing them. Consequences are irrelevant to whether punishment is owed, and can be relevant only within the limits desert has already fixed.

The consequence students find hardest. On Kant's account, punishing a guilty person is not a regrettable necessity to be minimised. It is required. A society that let a murderer go free because nothing would be gained by punishing him would, in Kant's language, be a party to the wrong.

The two passages

The right of retaliation

Kant's own text puts the principle plainly. Whatever undeserved evil you inflict upon another within the people, that you inflict upon yourself: if you strike yourself, you strike another; if you kill another, you kill yourself. This, he says, is the Right of Retaliation, in his Latin the ius talionis, and, properly understood, it is the only principle which, in regulating a public court as distinguished from mere private judgment, can definitely assign both the quality and the quantity of a just penalty.

Three things to notice.

It is a principle of measurement, not of vengeance. Kant's claim is not that the victim's family are entitled to satisfaction. It is that the offence itself supplies the standard by which a court can fix a sentence, and that no other principle can.