On one of the most common readings of the Republic, Plato means for us to agree with Socrates and his interlocutors that their aristocratic city is the just polis. For convenience, I call this the political reading. It is no wonder, of course, that this interpretation is as common as it is, since it might be one of the most natural interpretations of the Republic. I argue, though, that it faces a serious problem: Socrates and his interlocutors’ argument for the justice of the aristocratic city has certain deficits, and—more important—there is considerable evidence that Plato was aware of at least one of these deficits and that he thought it was obvious enough for his readers to see.
Marshall, Mason, "A Problem for the Political Reading of Plato's Republic" (2010). The Society for Ancient Greek Philosophy Newsletter. 347.