We have come to the end of Plato's Republic and the end of the podcast. In the final episode, Socrates satisfies Glaucon's challenge to show that a just state is always preferable to an unjust state and being a just person is always better than being unjust. He has previously described the just and unjust governments (kingship and aristocracy) and corresponding souls. Socrates now contrasts them to each stage of the degradation of the city-state and soul, concluding with a discussion of Tyranny and the tyrannical soul. The conclusion is that kingship and aristocracy are always preferable to any other type of government or soul, especially tyrannical states and souls.

Plato extends his analogy between the constitution of the city-state and the soul of the individual by presenting a theory about how the constitutions slowly devolve from the ideal (kingship or aristocracy) to the most imperfect (tyranny) and how this is mirrored by the slow degradation of the soul.

Plato's Allegory of the Cave is one of the most famous thought experiments in the history of Western philosophy. An allegory is "a story, poem, or picture that can be interpreted to reveal a hidden meaning, typically a moral or political one" (Oxford). The question asked by Plato scholars and repeated here is "What meaning is most consistent with the moral and political ideas promoted by Socrates in the preceding discussion about the form of the Good?"

Socrates tells Glaucon that philosophers should be kings because only they have access to the Form (concept) of the Good. The concept of Justice cannot be understood unless one understands its relationship with the Form of the Good. In order to explain this relationship, Socrates turns to an analogy -- the Sun and the power of the sun to shed light on things and make them visible.

This episode begin with Socrates' astounding claim that "only philosophers should be kings." However, he soon qualifies this with the remark that he does not mean philosopher in name only. He means philosophers who have a specific kind of knowledge that he calls "knowledge of the form Good." The remainder of this episode is a journey through the distinction between forms (concepts) and the particular things that participate in the forms, including forms that participate in other forms. What is the difference between beautiful things (works of art, music, sculpture) and the form Beauty itself? How does the form Beauty participate in the form Good?

Socrates argues in defense of his recommendation that women can and should be rulers in the ideal state. His argument is that there is nothing relevant about women that would prevent them from ruling. Second, he says that male and female rulers should be prevented from marrying or having a permanent sexual relationship with another member of the ruling class because this would make them partial to the need of their spouse, thereby detracting themselves from their main duty to promote the good of the state. Third, any newborn children of a ruler should be removed and taken to an isolated part of the city where professionals will care for, educate and raise them. No child will ever know their biological parents and no biological parents will ever know their children because (again) this would distract the parents from their main task -- to protect promote the good of all citizens.

This episode is a discussion of the concluding paragraphs of Republic, Book IV. It is about the question "Why do we need a theory to explain self-control?" Socrates would answer this by saying "Because we need to show how one and the same person can control his or her appetites or emotions." Socrates introduces the theory of a tripartite soul. We can control ourselves only if there is one part of the soul that does the controlling and the other parts that are controlled. But this account leads to the Humunculus Problem (if there are parts of the soul, then the parts must be directed to what they do by their own parts, and so on ad infinitum. This episode shows why a tripartite theory is unnecessary. The remainder of this episode discusses Socrates' theory of how justice and all the other virtues of the soul are tied either to tasks of the parts of the soul or to the "best relationships" between the parts of the soul.

If Socrates is to convince Glaucon that justice and injustice in the soul is like justice and injustice in the city-state, then he must prove that there are parts of the soul analogous to the three classes of the city-state. Socrates believes he can do this by using the Principle of Opposites. But having made his point he runs into another question: Is each part of the soul an entity (a "humunclus") that has its own parts?

Socrates takes the first steps toward discovering the meaning of justice in the city-state and the place in the city where it is most likely to be found. He puts forward two analogical arguments to prove that justice is found in the city only when there is an agreement between all classes of the city is founded on the principle of natural division of labor. Each person practices only one task in the city and that shall be the task for which he or she is naturally suited.

Glaucon asks Socrates if he can provide a defense of justice (right conduct) that will show not only that justice is good for the sake of its consequences but it is good in and of itself. In one of the most famous parts of Book II, Glaucon presents the myth of Gyges ring -- the ring of invisibility. Socrates must show that a just person would never use the ring to make himself invisible and do an unjust (wrong) act. There are other challenges of Glaucon. At the conclusion of Book II, Socrates begins to build his case by drawing an analogy between a just city and a just person.