Plato's city in the Republic is created as a perfectly just city ruled by philosopher kings that eventually will evolve into lower forms of constitutions, which will beget lesser forms of man. How do just philosopher kings allow their city and men to evolve into these lesser forms? How is it possible for Plato to basically say that injustice can be created from pure justice?.
In the Republic, Plato creates a city, a kallipolis, that is ruled by aristocracy, "which is rightly said to be good and just." This city Plato proves to be both the best and the happiest for the people. The way that this city is said to be purely just is because of its rulers. Plato defines these just rulers as the philosopher kings. Philosopher kings have knowledge and understanding of the Forms, they know what is good and follow only that absolute. Plato states that they are just and do only just acts, and they are the only ones fit to rule the aristocratic constitution. (VI 487 e).
In book VIII, Plato discusses four types of constitutions and their corresponding four characteristics of man that have descended from the aristocracy described above. These four types are known as timocracy, oligarchy, democracy, and tyranny. Plato characterizes these four types as four stages of disintegration from the original ideal kallipolis, with timocracy being the penultimate quality of state after aristocracy and tyranny being the worst form of constitution. .
Plato argues in book VIII how these four lower types of constitutions and characteristics of man descend from the just aristocracy. This is where Plato is flawed in his theory of decaying constitutions. How is it possible that these less just stages of constitution and man are created from the original perfect stage? More specifically, how can tyranny eventually be created from aristocracy if aristocracy is purely just, which Plato describes it to be? Plato's argument corresponding to these questions is that: .
