We ended last time with Glaucon posing the question that The Republic is supposed to answer: why is justice valued for its own sake? As Socrates pointed out at the end of Book I, this requires answering a second question: what is justice?
The attempt to characterize a just city is supposed to help us to answer those questions. By seeing what makes a city just, we will hopefully see what makes an individual just. In addition, the value of justice in the city will, hopefully, throw light on the value of justice for an individual.
Guardians were introduced to solve some of the luxurious city’s needs. (Plato later split this group between guardians, who rule, and auxiliaries, who make up the military force supporting the guardians.) Having introduced a military class, Plato set about describing their selection and education. It’s important to select good leaders and also to train them so that they will stick to their jobs rather than exploiting their power.
One interesting thing about this is that Plato hasn’t yet described why even the luxurious city needs leaders, people who govern the behavior of its members. The need for guardians came entirely from relations with people outside the city. We’ll get more of the story later; my only point is that we haven’t heard much yet.
Another interesting thing is that the myth of the metals is directed more at the guardians and auxiliaries than the rest of the city. We’re familiar with false beliefs that have the function of discouraging members of a society from pursuing their own interests. But these are usually directed at those closer to the bottom of society.
Plato will try to show that life in the just city is the best life for all concerned. So this sort of lie isn’t exploitative in the way that the familiar falsehoods that we’re typically concerned with are. It’s an interesting question whether “noble,” non-exploitative, lies like this play a legitimate role in our political lives or not. It’s a question that we’ll return to when we talk about Sidgwick’s utilitarianism and Rawls’s liberalism.