Having now established the character of the true philosopher, Socrates sets himself to the task of showing why the philosopher would, in the ideal state, be the best ruler. It follows logically that, since he understands the Forms, the philosopher is best fitted to rule; after all, it is he who understands truly the nature of reality. Besides, having come to maturity in his study of the arts and gymnastic, the philosopher will possess the cardinal virtues: wisdom, courage, temperance (discipline), and justice.
Because he knows what Justice and Goodness are, the philosopher would be best qualified to administer justice for the good of the citizens he rules. And because he loves Truth, the philosopher will not lie (he would hate a lie); he will not countenance a lie for his benefit or give tacit agreement to lies. Because his bodily wants and physical necessities are provided for him, the philosopher will not be covetous of material things; he will possess temperance and will conduct himself temperately in the interest of his subjects. The philosopher's whole life's training having been spent in gymnastic and in the pursuit of temperance, the philosopher will possess courage. He will not fear death in the field of battle, nor will he fear death from his political adversaries. For all these reasons, the philosopher will make the best ruler.
Adeimantus objects, saying that Socrates has such a way of arguing (his "Socratic method") that any listener must answer in the affirmative to his rhetorical questions. But Adeimantus disagrees with Socrates' conclusions. The good philosophers he sees around him, Adeimantus says, are worthless to the society they live in, and the bad philosophers are rogues. But whether because of their general worthlessness or their villainy, the philosophers Adeimantus sees are not fit to rule.
