Glaucon used the
Ring of Gyges to point out some interesting takes on
ethics in
Plato's book
The Republic.
The ethical life is a compromise between the life one wants to live and the life one wants to avoid. You hate sleeping on rocks in the rain, so you make a choice to work and have a place to live. This balance can be adjusted as needed during one's life.
If you were asked, would you rather live in a tar shack in the bayous of Louisiana or in Bill Gates' rambling monster mansion? Almost everyone would pick the life of luxury, if offered the chance. Hell, that's what the lottery system is based on - this choice, or a chance at it.
The life of luxury extends to a life where we are shielded from negative consequences. Bill Clinton lied under oath and got away with it. If you lied under oath, you can rest assured your ass would be behind bars. This difference between the groups, the oppressor/elite and the opressed/masses, is what Glaucon based his arguments on.
In the story, the shepherd, a good person, uses the ring to seduce, kill and steal. With the ring, he was immune from the consequences of his actions. The masses adopt rules, laws and morals to restrain the elite from taking advantage of the masses. The elite see these laws as restraints on their power, and so they attempt to subvert the system. We see an actress shoplift and get a slap on the hand - but if a young black woman from Harlem was accused, she would have an uphill battle and would probably wind up in prison. Is this moral?
The masses, Glaucon believed, wanted to be the elite, so they did allow some of the rules to be broken. The overall point of this process was happiness, the root goal of ethics. Once the shepherd had the power of the Ring of Gyges, the rules no longer applied to him. The shepherd followed a new moral code of self-interest.
Glaucon argued with Socrates that anyone in the situation of the shepherd would do the exact same thing. Anyone who says they wouldn't would be either a liar or a fool.