In the Republic, Glaucon argues that people are only just because they fear the consequences of behaving unjustly. He uses the traditional story of Gyges's ring to illustrate this. In the story, Gyges finds a magic ring that makes him invisible. He uses this ring to enter the queen's bedroom and seduce her, then conspires with the queen to murder the king and take his place.
Glaucon believes that anyone who could act as Gyges did with the certainty of escaping punishment would do so. This accords with the view of human nature expressed by Thomas Hobbes in his Leviathan. Hobbes believes people are driven principally by egotism. Since we are all approximately equal in abilities, we all believe that we have a good chance of overcoming our opponents. Therefore, human beings are in a state of constant war unless some greater power, the Leviathan, imposes his will on us and keeps our egos in check.
Hobbes, therefore, agrees with Glaucon that everyone would use Gyges's ring if he could. However, neither Plato nor Socrates, Glaucon's interlocutor in the dialogue, agrees with this position. While many people would use Gyges's ring for immoral ends, Socrates argues, there is good reason not to do so, meaning that a wise man would refrain. The reason is that we debase our souls by failing to follow the path of virtue, and one's primary duty is the care of one's own soul. Therefore, while Plato considers and expresses the same cynical view as Hobbes, he does not espouse it.