Platos Republic

Why do men behave justly? Is it because they fear societal punishment? Are they trembling before notions of divine retribution? Do the stronger elements of society scare the weak into submission in the name of law? Or do men behave justly because it is good for them to do so? Is justice, regardless of its rewards and punishments, a good thing in and of itself? How do we define justice? Plato sets out to answer these questions in the Republic. He wants to define justice, and to define it in such a way as to show that justice is worthwhile in and of itself. He meets these two challenges with a single solution: a definition of justice that appeals to human psychology, rather than to perceived behavior.

Plato’s strategy in the Republic is to first explicate the primary notion of societal, or political, justice, and then to derive an analogous concept of individual justice. In Books II, III, and IV, Plato identifies political justice as harmony in a structured political body. An ideal society consists of three main classes of people—producers (craftsmen, farmers, artisans, etc.), auxiliaries (warriors), and guardians (rulers); a society is just when relations between these three classes are right. Each group must perform its appropriate function, and only that function, and each must be in the right position of power in relation to the others. Rulers must rule, auxiliaries must uphold rulers’ convictions, and producers must limit themselves to exercising whatever skills nature granted them (farming, blacksmithing, painting, etc.) Justice is a principle of specialization: a principle that requires that each person fulfill the societal role to which nature fitted him and not interfere in any other business.

At the end of Book IV, Plato tries to show that individual justice mirrors political justice. He claims that the soul of every individual has a three part structure analagous to the three classes of a society. There is a rational part of the soul, which seeks after truth and is responsible for our philosophical inclinations; a spirited part of the soul, which desires honor and is responsible for our feelings of anger and indignation; and an appetitive part of the soul, which lusts after all sorts of things, but money most of all (since money must be used to fulfill any other base desire). The just individual can be defined in analogy with the just society; the three parts of his soul achieve the requisite relationships of power and influence in regard to one another.