Kant on punishment; or, why we need to punish people more severely.

Immanuel Kant wrote in Fundamental Principles of the Metaphysic of Morals (1785, trans. Thomas Kingsmill Abbott, 1934),

...it is easy to see how it happens that, although the conception of duty implies subjection to the law, we yet ascribe a certain dignity and sublimity to the person who fulfils all his duties. There is not, indeed, any sublimity in him, so far as he is subject to the moral law; but inasmuch as in regard to that very law he is likewise a legislator, and on that account alone subject to it, he has sublimity. We have also shown above that neither fear nor inclination, but simply respect for the law, is the spring which can give actions a moral worth. Our own will, so far as we suppose it to act only under the condition that its maxims are potentially universal laws, this ideal will which is possible to us is the proper object of respect; and the dignity of humanity consists just in this capacity of being universally legislative, though with the condition that it is itself subject to this same legislation.

Whenever I stumble across a news item like this one, I inevitably reconsider Kant's views on punishment. The notion of the Categorical Imperative must be considered in light of the fact that every moral agent is ultimately responsible for his own actions. Given free choice each action necessarily establishes, in relation to itself, a maxim stating that the action in question ought to be universally permissible. In choosing to attack the cab driver, the machete-wielding teenager willed that his action instantiate a universal law, available to and permissible for everyone. (Whether or not he was aware of this is immaterial, I think.) Kant's conception of retributive justice pivots on the ineluctable fact that an individual cannot justifiably complain about having his actions, once duly installed in the realm of the universal, turned back on himself. If for instance X were to commit murder – and in so doing establish murder as universally permissible – he could not object to being himself murdered.

Taken one step further, Kant argues in The Philosophy of Law (1796, trans. W. Hastie, 1887) that injustice and immorality demand rather than merely deserve retribution:

But what is the mode and measure of punishment which public justice takes as its principle and standard? It is just the principle of equality, by which the pointer of the Scale of Justice is made to incline no more to the one side than the other. It may be rendered by saying that the undeserved evil which any one commits on another, is to be regarded as perpetrated on himself. Hence it may be said: "If you slander another, you slander yourself; if you steal from another, you steal from yourself; if you strike another, you strike yourself, if you kill another, you kill yourself." This is the right of retaliation (jus 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.

This is why the wretched liberal philosophy of punishment currently in vogue – restitution, rehabilitation, and reintroduction – cannot properly force criminals to atone for acts of manifest evil in any acceptable way. Two years of comfortable incarceration does not swing the "pointer of the scale of justice" back into equilibrium.