In his sustained critique of popular notions of justice, Mill uses the common idiom “an eye for an eye and a tooth for a tooth.” Identifying the desire for vengeance as “primitive,” Mill writes that:
No rule on the subject recommends itself so strongly to the primitive and spontaneous sentiment of justice as the lex talionis, an eye for an eye and a tooth for a tooth. Though this principle of the Jewish and of the Mohammedan law has been generally abandoned in Europe as a practical maxim, there is, I suspect, in most minds, a secret hankering after it; and when retribution accidentally falls on an offender in that precise shape, the general feeling of satisfaction evinced bears witness how natural is the sentiment to which this repayment in kind is acceptable.
Here, Mill alludes to the “lex talionis,” an ancient conception of law that is broadly known under the idiom “an eye for an eye.” This principle has a long history. It is often associated with the Bible, but similar ideas can be found in older sources, including the Code of Hammurabi, a Babylonian legal text. Mill claims that this “primitive” understanding of justice, which emphasizes proportionate revenge, has been “generally abandoned in Europe,” though he also acknowledges that many Europeans have “a secret hankering after it.” Mill’s use of the idiom “eye for an eye” underscores what he believes to be the overly simplistic and bloodthirsty nature of this common attitude. Against this, he proposes the utilitarian model of justice, which would imagine punishment only as a means of ensuring the common good rather than as the execution of revenge.
In his discussion of the relationship between justice and vengeance, Mill uses the conventional idiom “just deserts.” Critiquing what he considers to be the limits of “the idea of justice” as “conceived by the general mind,” Mill writes:
Thirdly, it is universally considered just that each person should obtain that (whether good or evil) which he deserves, and unjust that he should obtain a good or be made to undergo an evil which he does not deserve. This is, perhaps, the clearest and most emphatic form in which the idea of justice is conceived by the general mind. As it involves the notion of desert, the question arises what constitutes desert? Speaking in a general way, a person is understood to deserve good if he does right, evil if he does wrong.
In accord with other utilitarian philosophers, Mill believes that maximizing collective pleasure or happiness should be the goal of both philosophy and politics. In outlining his theory, he examines the question of “justice,” which seems to offer a challenge to the utilitarian model. Most people, he acknowledges, have some basic, instinctive sense that people should be punished for doing things that are bad or evil, regardless of whether or not that punishment maximizes human happiness. Central, for Mill, to this popular conception of justice is the notion of “just deserts,” a long-lasting idiom that calls for an individual to receive reward or punishment for good or bad behavior, respectively. In this idiom, “desert” does not mean either an arid landscape nor a “dessert” following a meal, but rather, that which an individual deserves. Here, Mill uses this idiom to characterize a common attitude he thinks is ultimately mistaken.