In Book II of the Republic, Glaucon argues that "all who practice it [justice] do so unwillingly, as something necessary, not as something good." (358c) The common conception of justice in Plato's day was a social one, which involved the following of laws and conventions. Glaucon states that, for most people, "what the law commands they call lawful and just." (359) He uses the Ring of Gyges to show that "People value it [justice] not as a good but because they are too weak to do injustice with impunity." (359b)
This view of justice might lead one to Glaucon's argument. But, I will argue that his argument, based on this view, is wrong for two reasons. First, I believe that there are some things wrong with Glaucon's characterization of justice, which would not lead one to as depressing of a conclusion as Glaucon. Second, I will show that Glaucon cannot get the result he claims by necessity. Analytically, Glaucon's argument is unsound.
Glaucon sets up the Ring of Gyges argument as a thought experiment, which should clearly show us that "those who practice justice do it unwillingly and because they lack the power to do injustice." (359c) The ring, which grants invisibility to the wearer, is to allow both the just and the unjust person of our thoughts the "the freedom to do whatever they like." (359c) We will then keep a figurative eye on both as they go about their life. Glaucon maintains that we would "catch the just person red-handed travelling the same road as the unjust." (359c) His premise for this claim is an assumption that he makes—that humans "desire to outdo others and get more and more." (359c) "This," he maintains, "is what anyone's nature naturally pursues as good, but nature is forced by law into the perversion of treating fairness with respect." (359c)
I argue that this assumption of Glaucon's is not a naturally occurring process of human nature, or even of human society, but of a materialistic economy, such as we live in today, or one like the ancient Athens of Plato. Athens, along with the rest of Greece, had relatively recently escaped from the Dark Ages of Greek history. Their world had, and was still, undergoing radical changes. Influences and trade from the ancient Near East had been pouring in for a few hundred years. The city-states had progressed from the old kingdoms, through the aristocracies, and the tyrants into something much freer and open. A merchant class had arisen based on trade. Someone had to be buying all these goods. I am sure that life was much tougher for an ancient Athenian than for me today, but their economy was highly materialistic. It is easy to see why the masses of Glaucon's time may have had this view of justice, but it is a faulty view based on a faulty assumption.
Humans do not naturally desire to outdo one another, or desire to acquire more and more things. This is something that we are taught by our respective cultures. But, different cultures teach these in different ways. The desire to outdo one another can take many forms, some of which may accept or reject justice. Some ways may even demand justice. A society such as Glaucon's accepts justice. They use it as a tool; helpful when needed, ignored if at all possible. Many societies encouraged their members to outdo one another in limited situations, such as games of strength, but justice and fair play were still demanded.
Many societies, which we would call 'primitive', are not concerned with the accumulation of wealth. The fact that we call them 'primitive' is not properly a value judgement on our part. The aborigines of Australia and the !Kung bushmen of Africa are two examples. Daily survival in these societies is far more important than amassing 'things'. It is the more 'civilized', materialistic economies that teach us to value the accumulation of more and more.
Thus, I believe that Glaucon's assumption that humans "desire to outdo others and get more and more" (359c) is incorrect. It is, in fact, historically accurate in many societies throughout history, such as in Plato's Athens, but it is not a natural human desire.
This faulty assumption of Glaucon's leads him to declare that a just person would be no different than the unjust person in this situation. He would supposedly steal just as much from the market, he would have sex with whomever he wished, kill those who bother him, etc. This result might be achieved, if in fact, everyone believed as Glaucon does. It is clear that they do not though, as even Glaucon claims to be arguing this position only to get Socrates to give a better answer. I maintain that there are many just people, who may even have a reputation for injustice, that would rarely commit injustice in these circumstances. They would not rape or kill. They may steal a few pieces of food from the market if they or their family were starving, but this most certainly does not qualify as 'following the same path.'
Analytically, Glaucon's argument self-destructs. First, I'd like to offer a minor point. His belief that simple invisibility would allow one "the freedom to do whatever they like" (359c) is clearly naïve. Invisibility alone would not give one this freedom. He is, of course, free to change his thought experiment by adding whatever is necessary and sufficient to give our just and unjust person this freedom.
My major argument against Glaucon is that he cannot logically get from the possibility of acting unjust to the necessity, or actuality, of it. There is no logical connection between 'can' and 'will'. Even if Glaucon's assumption about human nature is valid there is still no necessity that would make a just person act just as unjust as the most unjust one would.
I have shown that Glaucon's argument is wrong for two reasons. First, I believe that his characterization of justice is wrong. Second, he cannot get the result he claims by necessity. His argument is unsound.
Plato, Republic Book II, in Morgan, Michael L., ed. Classics of Moral and Political Theory. 2nd ed, Indianapolis: Hackett Pub. Co, 1996.