Book V of Plato’s Republic begins with Socrates the establishment of their new city as both “good” and “right” (449a). In contrast, there are four other forms of bad cities, or governments, however before Socrates can elaborate on them he is interrupted when Polemarchus arose and whispered into the ear of Adeimantus. The concern that is now brought to the table is that of the proposed communism of women and children. Socrates is outnumbered by the votes of Polemarchus, Adeimantus, Glaucon, and Thrasymachus in needing to address this concern.
After they force Socrates to take up the question, he proposes two alternative, and more direct, questions that address the heart of the issue: 1) Is this communism possible? 2) Is it desirable? The communism of women is the consequence of the equality of the two sexes, particularly concerning the work they do. This demand for the equality of the sexes requires an entire upheaval of the city’s custom, and presupposes a return to what is according nature. The upheaval requires a justification on the ground that what is useful is what is most fair or noble. Utility replaces justice. It requires the most severe regulation of sexual reproduction and intercourse. However, there is a great difficulty in that men seem to naturally desire children of their own. Eros must be sacrificed for the sake of justice in the city.
The only relevant difference between the sexes is that men are physically stronger than women. Socrates uses this outlet to engage Glaucon in a discussion of war. The city must act as the form of a human being, with each person playing their respective part, rather than in parts (note the opposition to factionalism that is always present in democracy). Is it possible for this city to ever come into being? The only way, Socrates claims, is for the philosophers to become kings (472d). This leads to a discussion of what the philosopher is: a desirer of wisdom, or one who is willing to taste every kind of learning with gusto and insatiability. This leads to a discussion of knowledge, as distinct from opinion. In the same way that we experience the triad of non-being, becoming, and being; the relationship exists between ignorance, opinion, and knowledge.