Abstract
By considering carefully Socrates' invocations of 'compulsion' in Plato's Republic, I seek to explain how both justice and compulsion are crucial to the philosophers' decision to rule in Kallipolis, so that this decision does not contradict Socrates' central thesis that it is always in one's interests to act justly. On my account, the compulsion is provided by a law, made by the city's lawgivers, that requires people raised to be philosophers take turns ruling. Justice by itself does not require the philosophers to rule, but it does require them to obey just laws. I also consider the implications of this view for Plato's politics.