Book I, although very like a typical aporetic dialogue, turns out, as Socrates discovers, to be only a prelude to the real discussion. It raises the issues; it does not explore them. At the beginning of Book II, Glaucon steps in and restructures the argument of Thrasymachus, pressing Socrates to give an account of justice that shows both what it is and why it is better than injustice, not just in its consequences, but in itself. Glaucon does this in a memorable way by painting three related scenarios. In the first, Gyges discovers a magic ring that lets him do things without getting punished, and has a successful life doing things that would ordinarily be considered unjust. In the second, similar rings are given to a just person and an unjust person. And in the third, we do away with the rings and imagine an unjust person who is universally thought to be just and a just person who is universally thought to be unjust. The point of all three scenarios is to raise this fundamental challenge: People do not care about justice, do not regard it as valuable; instead, they care about the benefits, and especially the reputation, they associate with being just. People do not want to be just, but only to seem just. They want to outdo (pleonektein) other people, and only value justice insofar as it allows them to do so.
Adeimantus jumps in and looks at the same point from the opposite side: How do people actually praise justice? In what do they locate its worth and value? If a father is encouraging his sons to be just, he speaks of reputation and the kind of honors that are given to people who are thought to be just. He notes that they support their views by appeal to the poets, people like Hesiod and Homer, who talk about virtue in terms of "the esteem of the gods" (363a). People tell stories of the material rewards given to virtuous men by the gods. In all of this they treat virtue as beautiful (kalon) but extremely difficult (chalepon) and painful (epiponon), while they treat vice as pleasant and easy and profitable (lysitelestera). Further, people tell stories about how you can compensate for your wrongdoing by making sacrifices to the gods, so that if a rich person has done something wrong he can fix it with an easy ritual rather than a serious punishment. If we add all this up, Adeimantus says, what will be the effect on the young? Surely it is all a way of teaching them that it is more important to have "a facade of illusory virtue" (365c) than virtue itself?
Socrates replies that this challenge may be beyond his ability to meet, but promises to do what he can. He begins by proposing a method. In order to find out what justice is in the individual, it might help to look at justice on a much larger scale, since things may be obvious when justice is magnified that wouldn't be if we only looked at the little version. In short, we should look at what justice is in a city (polis) and use what we learn from that in order to determine what justice is in a life. Thus Socrates begins describing his first ideal city.
Cities consist of people getting together to get what they need and provide what others need. They are built on a principle of division of labor. So a city must have the kinds of skilled labor that allows this to happen; it needs farmers, cobblers, builders, and so forth. It will also need people to handle trade with other cities, merchants, sailors, and the like. It will need people to handle the buying and selling, so that farmers, for instance, don't have to waste precious farming time sitting around in the marketplace; in other words, it will need retailers. It will need people to be manual laborers for odd jobs and heavy lifting. So let's assume our city is up and running. What will life in it be like? Socrates says,
They'll produce bread, wine, clothes, and shoes, won't they? They'll build houses, work naked and barefoot in the summer, and wear adequate clothing and shoes in the winter. For food, they'll knead and cook the flour and meal they've made from wheat and barley. They'll put their honest cakes and loaves on reeds or clean loaves, and, reclining on beds strewn with yew and myrtle, they'll feast with their children, drink their wine, and, crowned with wreaths, hymn the gods. They'll enjoy sex with one another but bear no more children than their resources allow, lest they fall into either poverty or war. (372a-b)
Glaucon interrupts and says that they don't have any delicacies, and so Socrates jokingly replies that, of course, they need delicacies, things like salt olives, cheese, and yams, with fine desserts like figs, chickpeas, and beans. Glaucon insists, though, that the problem with this ideal city proposed by Socrates it is that it is "a city for pigs" (372d); people need proper couches and tables, and have the same kinds of fine foods that are easily found in Athens. Socrates responds that this changes things considerably:
It isn't merely the origin of a city that we're considering, it seems, but the origin of a luxurious city. And that may not be a bad idea, for by examining it, we might very well see how justice and injustice grow up in cities. Yet the true city, in my opinion, is the one we've described, the healthy one, as it were. But let's study a city with a fever, if that's what you want. (372e-373a)
Thus we begin the second ideal city. Now that luxury is a matter of importance, the city must expand massively to include all sorts of arts and occupations devoted to entertainment and pleasure. And as it expands, it increasingly becomes likely that what it has is not always enough, and thus we find the origin of war. The advent of war and conflict requires the development of a class of people devoted to protection of the city and its good. These guardians, however, cannot just be any kind of person; they need to be "both gentle (praon) and high-spirited (megalothymon) at the same time" (375c). But meekness and having a big thymos are not obviously consistent. Socrates proposes that it is philosophy that mediates between the two and makes them consistent with each other. The guardians of the city will have to be people of "philosophy, spirit, speed, and strength" (376c).
At this point, they turn to look at what kind of education is required for the guardians of the city, looking at the two major forms of exercise in the Greek world: music and poetry for the soul and athletics for the body. Adeimantus, of course, had raised the problem of people using poets to praise justice in ways that only regarded its appearance, rather than its substance; this problem exercises them almost immediately. I don't intend to look in detail at all the proposals for how music, poetry, and athletics should be handled, but I do want to point out something important that is often missed: the discussion of these topics indirectly covers almost all of the ground that will be covered by the rest of the dialogue. For instance, in discussing music, the descriptions used in criticizing or praising different kinds of music will be echoed later on in the descriptions used to criticize or praise different kinds of political constitutions.
All the guardians must be tested repeatedly for whether they put the good of the city first and foremost, and, moreover, they must be taught to avoid the things that tend to corrupt politicians, with money being first and foremost.
* Notice that Glaucon brings up the distinction between appearance and reality immediately; this is one of only several ways in which Plato depicts philosophical discussion as being parallel to and analogous with moral life. Socrates philosophizes in the way the just man lives his life; sophists like Thrasymachus philosophize in a might-makes-right way, preferring the appearance of success (winning the argument) to real success (discovering truth). As I've noted before, Plato is highly sophisticated when it comes to arguments; his arguments often do not merely tend toward a conclusion but toward several conclusions simultaneously, across several different areas of life. We will see this throughout this dialogue.
* It is easy for us to miss it, but the authochthony myth, about the citizens being born out of the earth, at the end of Book III tells us something important about the city, and is not some random thing pulled out of nowhere. One of the major differences between Athens and Sparta is that Sparta was founded by invasion. This is why Sparta had the structure it did, with the Spartan citizens sitting on top of a population of helots with no significant rights: the helots were the descendants of the original inhabitants of the region. Athens had no such origin, and, indeed, the Athenians described themselves as autochthonous: they grew up from the land. Because of this they had a particular kind of freedom, since they had no obligations to another city (like a city founded by colonization would) and they were not dependent on a population other than themselves (like Sparta). And, moreover, as Socrates says of the guardians, they regarded the land as theirs in a way that went far beyond being a place of residence: it was not just their home but in a sense their mother. We've seen the political and civic importance of autochthony elsewhere, in Critias and the Statesman.
* I think most interpretations of the Republic founder on not taking seriously the fact that the city discussed for most of the dialogue is explicitly regarded by Socrates as a second-best city. Much of the strangeness of that city is quite clearly deliberate, in order to make the point that luxury increases the danger of pleonexia, grasping for more, which is recognized from Book I on as the cause of injustice. A just city with luxuries has to be structured so that this attempt to outdo or have more than others is almost impossible despite the luxuries, and it is this that requires all the drastic measures discussed in the book.
Now it is time for Adeimantus to jump in and object. It doesn't seem like the lives of these guardians is very happy (eudaimona). But Socrates notes that, while at this point they should not presume that the guardians aren't happy, nonetheless the happiness of the guardians is not the primary concern at this point, since we are looking at what makes a whole city run well -- at this point, our concern is with the happy city, not happy individuals. Adeimantus notes that that's well and good, but inequality in wealth might make a significant difference among cities. Socrates responds that this overlooks an important point: a city is a city insofar as it is united, but most of the things we call cities are in fact not perfectly united but might equally be considered groups of cities, consisting of at least a city of the wealthy and a city of the poor. (This, like everything else in these books, will be echoed later.) For the ideal city to work as it should, however, it has to work as a unity, not as a group of smaller cities that can be potentially in conflict.
Because of this, the city will have to be such that all the citizens in it have all their goods in common, and education will have to be carefully constrained so that young people understand this from an early age and aren't tempted by other ways of doing things. The irony is that this means that the city doesn't require all that many laws: as long as people understand the importance of maintaining good and are educated so that they continue to do so, there isn't much need to dictate to them the details of what they should do. The constant making and amending of laws is a sign of the sickness of a city; it is analogous to a medical patient who keeps trying treatments to handle the symptoms of his disease while refusing to change his life and live in such a way as to get rid of the disease itself. If one lives healthily, serious medical treatment becomes a merely occasional thing; if a city works as a unity, new laws are a merely occasional thing. This is why education is so important; if you want the dye of justice to be color-fast in the city, you have to make it so that it will not be scrubbed out by "even such extremely effective detergents as pleasure, pain, fear, and desire" (430a), and education is how you do this.
Having laid out the basic elements of the city, Socrates notes that it exhibits, in its own way, the virtues of prudence, fortitude, temperance, and justice. If they want to see more clearly what justice is, then, they just have to abstract it from the other three virtues -- Socrates in a delightful passage (432b and following) describes it as hunting (compare the Sophist). And thus we actually get Socrates's definition of justice: it is "doing one's own work and not meddling with what isn't one's own" (433a), but only if we understand it in light of the city as a whole. What makes the city just is that everyone does what will contribute to the good of the whole.
The just individual, then, is the individual who participates in this same form of justice, although on a different scale. We have different parts in us. Just as the city has money-makers, we have desires; just as the city has auxiliaries, we have thymos; just as the city has guardians, we have reason. We are just when all of these parts doing its part for the good of the whole, as long as we recognize that this is a matter of internal activity rather than external behavior (which has to do with appearance): "One who is just does not allow any part of himself to do the work of another part or allow the various classes within him to meddle with each other" (443d). Injustice, on the other hand, is a sort of civil war or rebellion, in which one part puts its immediate object above the good of the whole.
* Book IV is, of course, one of the key texts for the tradition of the cardinal virtues.
* The anecdote about Leontius seems to have been a common one; he was said to have a taste for very pale boys. Thus the (extraordinarily morbid) joke about his quandary on coming across the corpses of boys.
We can go further, and recognize that to every general kind of political constitution there corresponds a kind of soul. However, Socrates will not be able to get to these until Book VIII, because now Polemarchus jumps in with an interruption. Socrates had said that in the city goods should be in common, and in passing had included wives as one of the goods. Polemarchus wants to know about this, and Adeimantus, Glaucon, and Thrasymachus all agree. Socrates complains that they are asking him to start over again, but they insist.
What then happens is somewhat unexpected, since Socrates begins by arguing that women should be educated in the same way as men. Men and women are obviously not the same, but they differen only with regard "to a particular craft or way of life" (454d):
Then there is no way of life concerned with the management of the city that belongs to a woman because she's a woman or to a man because he's a man, but the various natures are distributed in the same way in both creatures. (455d)
Given this, the relations between women and men are simply to be governed on those principles that will best contribute to the good of the city; they are not an exception to the overall approach. (It's not immediately obvious but it becomes clear that one of the effects of this argument is that a woman cannot be treated as mere property or the personal possession of a man, but only as a citizen.) Sex and procreation are goods to be had in common, but as common goods they are to be done only for the good of the whole city. I won't go into detail about the practices proposed, but the implication of them as a whole is, of course, that everyone regards the whole city as their family, and that nobody ever plays favorites with their own children (in part because it's arranged that they don't know who they are). Thus we get an overall picture:
You agree, then, that the women and men should associate with one another in education, in things having to do with education, in things having to do with children, and in guarding the other citizens in the way we've described; that both when they remain in the city and when they go to war, they must guard together and hunt together like dogs and share in everything as far as possible; and that by doing so they'll be doing what's best and not something contrary either to woman's nature as compared with man's or to the natural association of men and women with one another.
This discussion leads to a discussion of behavior in war in which Socrates criticizes common Greek war practices, like enslavement of other Greeks or despoiling the dead. (It's worth remembering that according to Plato, Socrates fought in three battles of the Peloponnesian War, and so must have seen such practices up close.) He articulates the very important principle in ethics of war: "their attitude of mind should be that of people who'll one day be reconciled and who won't always be at war" (470d). One of the implications of this entire argument is that the Greeks, who should in some sense all together act as one city, nonetheless treat each other in ways that would be considered atrocious behavior if it were done within one city.
Socrates is then pressed on the question of whether such a city is even possible, and notes that since the point was to discover justice, this is not essential, but he does go on to look at the question of how a real-life city might come into existence that would approximate the ideal one. This gives us one of the most famous passages in the entire dialogue:
Until philosophers rule as kings in cities or those who are now called kings and leading men genuinely and adequately philosophize, that is, until political power and philosophy entirely coincide, while the many natures who at present pursue either one exclusively are forcibly prevented from doing so, cities will have no rest from evils, Glaucon, nor, I think will the human race. (473c-d)
'Philosopher' does not, of course, mean someone who gives themselves that title on the basis of taking a few classes and writing a few papers. Rather, it means someone who loves the whole of wisdom, and thus the sight of truth. They are the people who will not stop at beautiful things but will rise to the beautiful itself (cp. the Symposium). They seek not opinion (doxa) but knowledge (episteme). Socrates will explore this further in the books to follow.
* It is almost certainly deliberate that Polemarchus physically grabs Adeimantus's cloak; Polemarchus's slave at the beginning of the dialogue did the same with Socrates. Polemarchus is associated with force from the beginning and continues to be here; since he was a famous democrat, this is almost certainly a comment about the democratic kind of soul Polemarchus has.
* It's worth noting that Socrates also argues that women can and should be educated in Xenophon's Symposium; it's not as bold a proposal as Plato puts in his mouth, but that makes two students of Socrates who attribute to him the view that women should be regarded as capable of education, a startling idea in a society in which women had the rights not of full citizens but only of minors. It is notable as well that when Socrates says that women should be taught music, poetry, and athletics exactly like men, Glaucon's response (452a) is not definite agreement but merely the cautious claim that that seems to follow from what Socrates has said. Plato is very explicit that what is being proposed is a radical change to the Greek way of life (e.g., 456c).
* On the other side, Plato's Socrates takes the Greek practice of infanticide of imperfect infants as obvious (460c).
* The philosopher-king passage hearkens back to the earlier discussion in Book I in which Socrates argues that good rulers would have to be compelled to rule; here Socrates says that the statesman must be forced to be philosophical and the philosophers must be forced to be statesmen.