Plato and John Stuart Mill Glaucon's challenge to Socrates at the beginning of Book II of Plato's Republic is to clarify in what sense justice is a human "good." Glaucon begins by separating goods into three categories: those which are harmless pleasures with no results, those things which are good in themselves but also lead to good results (like knowledge or health), and those which are unpleasant in themselves yet lead to good results (like caring for the sick, or physical exercise). Glaucon wants to know how Socrates would characterize justice in these categories. This leads Glaucon to the famous discussion of the "ring of Gyges" -- like the ring of Bilbo Baggins in The Hobbit, Gyges' ring confers invisibility on the wearer. Gyges is a shepherd who, according to myth, discovered such a ring and used it to sleep with the local queen, kill the king, and take over the country. Glaucon tells the story to challenge Socrates to clarify the difference between a just and an unjust man, if we imagine both types had the chance to use Gyges' ring: "the just man would put one on, and the unjust man the other, no one, as it would seem, would be so adamant as to stick by justice and bring himself to keep away from what belongs to others and not lay hold of it, although he had license to take what he wanted from the market without fear, and to go into houses and have intercourse with whomever he wanted, and to slay or release from bonds whomever he wanted, and to do other things as an equal to a god among humans. And in so doing, one would act no differently from the other, but both would go the same way" (1991: 37). This is Glaucon's argument, and it is astonishingly...

Socrates gives the rather un-cynical response to the challenge posed by Glaucon's invocation of Gyges' ring that -- in an inversion of the notion that virtue is invariably its own reward -- vice would prove to be its own form of punishment to the invisible person. The wearer of the ring of Gyges would not be able to abide his own conduct if he devoted himself purely to injustice and selfishness.
But what if we replaced Socrates in this argument with John Stuart Mill? We can, to a certain degree, construct what Mill's response to Glaucon might be, from an examination of the fifth and final chapter from Mill's work Utilitarianism, which bears the title "On the Connexion between Justice and Utility." In other words, this is Mill's own direct statement on the subject of justice, and how it relates overall to his ethical principles. We must begin by examining Mill's position overall -- to a certain degree, it bears a resemblance to Glaucon's, in approaching Socrates initially on the question of different types of human "good." This is what Mill's Utilitarianism aims to do: Mill wishes to establish the ethical value, good or bad, of an action is derived from the results of the action, not from some quality inherent in the action itself. As he defines the principle in Chapter 2 of Utilitarianism: "The creed which accepts as the foundation of morals, Utility, or the Greatest Happiness Principle, holds that actions are right in proportion as they tend to promote happiness, wrong as they tend to produce the reverse of happiness." In…