The next thing Socrates wants to explain is how all human beings are educated, and he does this with a (super famous) story (in this case an allegory) about a cave:
Imagine all of humanity is in a deep, enormous cave with one really long tunnel that leads out to a little speck of light.
Now, all these folks have been tied up since childhood so that they can't move and can only see what's in front of them. There's no looking side-to-side, or behind.
The only light they have in this cave comes from some fires, and in front of them there's this big shadow-puppet show going on, which projects all kinds of different things and shapes.
Glaucon interrupts and says this is a weird story, but Socrates says it's not that weird, because that's how we all live.
Socrates goes on. These people in the cave know nothing about how they really look, or about how anyone around them really looks; all they can see is what is reflected by the fire.
Socrates imagines that these prisoners talk to each other about the shadows they see projected. They give everything they see names, and they believe that the truth consists of just these shadows that are projected on the wall.
All right. Now imagine that one of these prisoners manages to free himself and is able to actually look around for the first time. He'll be partly blinded by all the unfamiliar light, and he won't know what to make of the actual objects he's seeing around him. If someone comes and tells him that his entire life up to this point has consisted of watching silly shadows, and that the real world is all around him, he'll freak and probably not even believe this person. And even if this person tries to point the fire out to him so that he'll understand the situation, the freed prisoner's eyes will burn, and he will much rather return to the shadows his eyes are able to see.
So, let's say this other person gets aggressive and literally drags our freed prisoner out into the sunlight. What will happen then? Well, the freed prisoner will be so utterly blinded by the light that he won't be able to see anything. He still may not believe what this other person had been claiming.
But slowly, as the freed prisoner becomes accustomed to the light, he'll be able to see shadows, then objects, then the reflection of the sun, and then the sun itself, which will allow him to begin to understand the seasons and the workings of the real world.
So now that the freed prisoner understands these things, he'll remember all the other prisoners in the cave and go to free them.
Now, in the cave, the prisoners have come up with all kinds of rewards and honors for the ones who can best describe or predict the shadow images that go by, but Socrates suspects that once freed, the former prisoner will not be interested in having those honors. Furthermore, if he tries to sit down with them and explain what he has seen, the others will laugh at him and say he is the one with some serious delusion issues and vision problems. In fact, if one of the other prisoners is able to free his hands, he'll probably kill the freed prisoner for disturbing the peace.
Now, Socrates explains that this story corresponds to their earlier conversation about the good.
The cave is this visible, actual world; the light in the fire is the sun; the process of going up and leaving the cave is the soul's journey toward the intelligible; and the real world revealed at the top is the idea of the good. Once you see the good, you desire nothing else.
Socrates says that it shouldn't be a surprise that those who have been enlightened seem a bit weird and crazy, because they are like the prisoner coming back into the cave, having to readjust to its darkness and being asked to have strong opinions about these silly shadows on the wall.
So, we shouldn't laugh at people who are transitioning from darkness to light, because even though it is disorienting at first, this process is ultimately a very good thing.
Education, therefore, isn't just about filling the soul with new information; it's more like a whole transformation in which the soul slowly gets used to thinking about and contemplating true reality.
The capacity to think about the true reality is already there; it's just often directed at the wrong thing.
Other virtues are added to the soul later, as it practices and learns the good—though this can, of course, be complicated by bad habits which drag the soul down and turns its vision away from the good.
So, it's clear that the city can't be guarded either by people who have had no education or experience with truth or by people who have immersed themselves too completely in education, since they won't have any public interests.
Instead, they need to make sure that the best kind of people get exactly the education they've been outlining: they need make the ascent out of the cave to see the good. And what's more, they need to make sure that these people don't just stay and hang out in the land of the good but go back down into the cave and try to share what they've learned with the others.
Glaucon is horrified by this idea: he thinks it will punish their philosopher-guardians. But Socrates reminds him that the most important job of the guardians is to care for everyone as a whole. This is completely crucial to the entire project, since each time these philosophers descend, they'll be better and better able to understand how foolish the shadows and darkness are. Their willingness to descend will also be a sign that they are actually excited about the reality of ruling and caring, which is something Socrates believes is crucial for a happy city.
In this way, the city will be governed by justice and will function harmoniously, since everyone will understand the necessity of his or her role.
Even though philosophers are not politically inclined, everyone agrees (for like the zillionth time, we know) that they will make the best leaders.
Next, Socrates wants to explain what kinds of education will enable the soul to make the ascent from darkness into light.
Socrates reminds everyone that the guardians can't just be intellectual; they need to be warlike, too, so that will have to factor into their education scheme.
Earlier, the group decided that the best education comprised of music and athletics. But athletics isn't stable enough: it deals with the body, which isn't immortal, so the group decide that athletics won't work.
Music won't work, either, because it teaches by similarity: you become harmonious by being exposed to harmony. These philosophers, though, will need to know. They can't just learn habits by means of similarities.
The Study of Numbers and Calculations
What they decide is necessary is calculation and numbering, since that is a skill universally useful. It's applicable to pretty much everything.
Next, Socrates claims that different kinds of things and sensations produce different desires for intellectual consideration. On the one hand, there are simple things that appear to be obvious, so people don't give them a lot of thought. On the other hand, there are complex things, often things that seem to be contradictions, and people are naturally inclined to devote much time and thought to them.
These two categories also apply to the two categories of things Socrates established way back when: 1) the visible and 2) the intellectual. We don't necessarily think too hard about visual things, because things just look how they look. But when we think more deeply about something, about why it looks that way or how it could look that way, we are prompted to be more thoughtful. So, the intellectual world is more likely to foster deep consideration.
Now, since deep consideration is a way to escape the cave, it follows that the intellectual world is more likely to be of help in trying to accomplish this.
Going back to the study of numbers, Socrates wants to consider the idea of the number one. He asks whether the number one will make people think or not. The group agrees that it will make people think because, as a concept, it is kind of contradictory: it can represent a single thing, but it can also be used to describe a single multitude of things, like a single crowd.
So, they decide that the number one—and all other numbers, and the study of calculation in general—leads people to intense intellectual activity. Therefore, it leads them toward truth.
Socrates recommends that they make studying calculation a law. He wants philosophers to study it in such a way as to comprehend the intellectual meaning of numbers themselves. It shouldn't just be about the practical use of math for everyday needs.
Socrates continues to praise math as a wonderful way to contemplate the good because it so clearly exists in a realm beyond visible objects. Furthermore, because math is so complicated, people who are good at it tend to be good at everything else.
Areas of Study that Lead to the Good
Next, Socrates wants to consider geometry. Glaucon says that geometry would definitely be a good idea, since it's so useful for war.
However, Socrates says that you only need to know a very little bit of geometry to make it useful in war, whereas he wants to determine the effectiveness of entire disciplines in preparing people for intellectual consideration.
Socrates suggests that even though some people talk about geometry in an overly practical way, it's actually quite intellectual because it deals with absolute, unchanging truths. For this reason, it is clearly a study that will lead to the good, and it should be part of education in their city.
Next, they consider astronomy. Glaucon immediately endorses it for all the useful things it can do. But Socrates again teases him for being so fixated on the useful, when what they really care about is the ideal. He says that they've actually jumped a bit too far ahead: after geometry, they should consider solid, 3D geometry.
Glaucon isn't as enthusiastic about this area of study, because he says it hasn't been really figured out yet. Socrates admits that's true, but he bets that if a city and intelligent people put their minds to it, a lot of progress could be made.
On to astronomy. Glaucon again endorses it, but this time it's because he's sure that anything that is the study of the heavens will be good for the soul.
Socrates isn't so convinced. He says that looking up at the heavens isn't the same thing as actually contemplating them. Since he believes the only kind of studies that lead to the good are the ones that involve a contemplation of things that truly are (and that are invisible), astronomy doesn't qualify.
Instead, Socrates recommends a different version of studying the heavens, one not concerned with movements and visual things but with the actual divine will embodied by the heavens.
After considering astronomy, Socrates wants to consider an area of study called antistrophe, which he says is the study of harmonic movement.
Socrates says the he doesn't want anyone in their city to be studying imperfect things, so they'll need to be careful about how their citizens study harmony.
They won't allow any study of harmony that involves poorly played instruments, and they'll only allow study that encourages a deeper understanding of numbers.
They all agree that after having examined these various disciplines, it seems that they've chosen the best ones to lead an aspiring philosopher out of the darkness of the cave. Socrates says, however, that there is still one greater area of study they haven't considered. This one is the most crucial in enabling this path of enlightenment, and it's called dialectic.
Brain bite! Dialectic? Don't worry: this is just a fancy word that describes an argument where multiple people speak, voice different opinions, and hopefully, as a result, reach the truth. So, it's pretty much your typical kind of argument, but Plato is the guy who made it so famous.
Socrates again describes how the philosopher, having pursued dialectic and the rest of the education outlined, will be in a position where everything looks different: the phantoms of the cave will exposed as... yep, just phantoms.
Glaucon says that what Socrates says is completely convincing but, at the same time, still kind of hard to believe. He wants Socrates to talk more about what dialectic is and what forms it can take.
Socrates says this will be difficult: Glaucon might not be able to follow it, since such an inquiry will lead them to look at truth itself.
Socrates goes ahead, though, and says that dialectic alone has the power to reveal the greatest truths of philosophy.
The other disciplines they've mentioned—geometry, calculation, etc.—all help the mind understand bits and pieces of bigger truths, but they are still only concerned with the small part that pertains to their area of study. Dialectic is the area of study dedicated to the big picture of truth itself.
Socrates reminds Glaucon that earlier, they had outlined four categories of mental activity: 1) knowledge, 2) thought, 3) truth, and 4) imagination. The first two categories together were called "intellection" and the second two "opinion."
Socrates says they should maintain this system, and they should remember that the disciplines they've been discussing fall into the category of 2) thought. Intellection in general deals with being (the way things actually are), whereas opinion deals with things coming into being (attempts to understand the way things are). But Socrates wants to leave these categories alone for now and move on.
Socrates wants to talk about understanding and the role of dialectical thinking. He suggests that a dialectic person is able to understand the actual being of each thing, whereas someone who isn't dialectic isn't able to actually understand what things are, in and of themselves.
Understand what things are, in and of themselves, means understanding the idea of the good, not just being able to recognize a bunch of things you think are good (that's just having an opinion). Now, this isn't to say that sometimes opinions can't point in the right direction, or that opinions aren't sometimes able to lead to understanding. But even this understanding will only be partial, because it's still based on opinion and hasn't been thought about deeply enough to be considered knowledge.
Socrates asks about Glaucon's children. He wants to know whether Glaucon would allow them to become rulers of a city if they were clearly irrational. Glaucon assures him "no way."
Socrates makes sure Glaucon is on board with this whole dialectic-is-the-best thing. Glaucon is.
More on Educating Philosopher-Kings
Now that they've outlined this educational program, they need to figure out who will learn it and how.
Socrates reminds them that they decided to choose rulers who were moderate, courageous, and, yep, good looking. He says they should add the following requirements: candidates should learn all the above disciplines quickly, easily, and with determination.
Rulers will also need to have good memories, and they should never be afraid of hard work. These qualities are especially important, because philosophy has gotten a bad rap lately as a result of less-than-stellar people taking it up.
A philosopher can't be the kind of person who only likes some things about philosophy; he has to be willing to do it all. He also can't be the kind of person who says he's against lying but actually accepts lies he hears all the time.
They need to be very careful to be on the lookout for the best men: they don't want to be in a situation where someone less awesome is chosen just because no one knew how to be a good judge of character.
If they do find someone who is the best of the best, it seems impossible that the city won't be just.
Socrates briefly apologizes for having got too emotional just then. He just hates the idea that philosophy isn't as respected and revered as it should be. Glaucon assures him he didn't come off as emotional, and they proceed.
Socrates reminds everyone that earlier they had suggested that the best leaders of the city would be older people, but with this new regime they've come up with, they now want to start young.
Children should be given all the education they've described, but it shouldn't forced on them; they want people who are naturally interested, not those who have been forced.
In fact, the best educators know that play, not strict discipline, is the best method for education, because it shows what children naturally incline toward. Socrates also reminds everyone that they decided to have children witness battles to learn warfare.
Often children have been exposed to all these various things. Those who are most persistent and eager will be selected after they've done a couple years of intense athletic training (so probably when they're around 21).
Those who have been chosen will now be taught how the various disciplines they've learned are all connected, and they'll learn the reason they've been learning them. This phase will be a further test, because those who are able to grasp these big, umbrella concepts are dialectical, while those can't aren't.
Next, once these select few reach 30, they'll need to make sure that they are the kind of people willing to give up their reliance on their senses and follow the invisible truth. That's a tough job to oversee.
Why so tough? Well, Socrates says it's because the study of dialectic can very easily lead people to become fake and unruly (many who study it are both), because it often involves a realization that the morals and values you've held near and dear for your whole life are actually wrong. If you realize this without knowing where to turn to find what's right, you'll become sad, unhappy, and false.
Socrates compares the bad dialectician to an orphaned child who, once he realizes that his parents aren't actually his parents—and that he won't be able to find his real parents—turns away in anger from his adoptive parents and joins forces with some empty flatterers who at least make him feel better.
Socrates also recommends that they be careful in not allowing young children to be exposed to the art of dialectic. Young children won't fully understand how it works; they might misuse the art of dialectic and foolishly imitate dialecticians, not knowing what they're saying until they've become young adults apathetic about the whole thing.
A more mature person, in contrast, will be interested in discussing truth itself and will treat discussion honorably and sensibly. Moreover, these mature and sensible people should only argue with other mature and sensible people, in order to keep the argument dignified and productive.
After they've been allowed to study pure dialectic for about 5 years, these young rulers-in-training will need to go back into the cave and take up the practical responsibilities of leadership. This will also need to be monitored, in order to make sure these people remain strong and true to their education.
The rulers-to-be will do this for 15 years. Once they've reached the age of 50, they'll finally be allowed full and compete access to the knowledge of the good. They will spend most of the rest of their lives contemplating this good through philosophy, but will occasionally take turns ruling the city and educating other men to become like them. Once they die, they'll go off to heaven and be praised and honored by the city they left.
Glaucon says Socrates has described such beautiful ruling men that he's like an amazing sculptor making masterpiece statues. Socrates reminds Glaucon that he wasn't just describing ruling men; he was describing ruling women, too.
They all agree that what they've outlined is the ideal form of government, and while it may be difficult to set up, it's not impossible. Once philosophers take over as rulers of the city, the whole city will change for the better, because the philosophers will have zero interest in your typical honors and wealth. They will only want the very best for the city.
Socrates thinks the fastest way to set up a city like this would be to have some philosophers take children older than 10 from their parents and raise them in the country, away from all the bad influences of the world. That way, they'll begin to cultivate a generation of untarnished intellectuals. Glaucon agrees.