PDF Summary:The Republic, by Plato

Ancient Greek philosopher Plato’s The Republic is one of the foundations of the Western philosophical canon. Through elaborate scenes, discussions, metaphors, and arguments, The Republic defines justice, the human soul, the ideal society, and the foundational structure of the universe itself. Plato intertwines these complicated topics to argue that living morally is good for its own sake.

In our guide to The Republic, we’ll discuss Plato’s key arguments, images, and allegories about morality, politics, and knowledge. This includes but isn’t limited to Plato’s ideal city, his concept of philosopher kings, and his allegory of the cave. Through our commentary, we’ll provide additional context to Plato’s philosophy, describe the society he wrote it in, and cite scholarly interpretations of his ideas.

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Understanding the Ship

This ship serves as an allegory for Athens. The incompetent captain and power-hungry sailors represent politicians and orators, while the navigator represents the philosopher. Just as the navigator has the necessary seafaring knowledge to guide the ship, the philosopher has the necessary moral knowledge to guide society. And just as the navigator avoids petty power politics and is ignored as a result, philosophers aren’t interested in power and wealth and are therefore ignored.

Socrates argues that just as the navigator is the ideal leader of the ship, the philosopher is the ideal ruler of society. The philosopher’s lack of interest in power and wealth means they’ll be less corrupt, while their focus on knowledge makes them the most competent. Their dedication to knowledge also requires self-control and the courage to keep searching for answers to abstract, universal questions—all ideal qualities in a ruler.

(Shortform note: When Socrates talks about a philosopher, he uses a literal definition of the word. The word philosophy derives from the Greek “philosophia,” which consists of “philo,” or love, and “sophia,” or wisdom. Therefore, a philosopher is literally a “lover of wisdom” rather than the type of academic we associate the word with today. This is why Socrates can securely say that by definition, philosophers love and desire wisdom above all else.)

Allegory #2: The Divided Line

To further elaborate on why philosophical knowledge is superior for guiding society, Socrates outlines his theory of human thought and knowledge.

According to Socrates, there’s a hierarchy of human thought—some thoughts or claims are better than others. He argues that the more provable, universal, and unchanging a thought is, the better it is because these criteria determine how certain we can be of its truth. To further illustrate this hierarchy of truth, Socrates compares thoughts to objects in the world. He categorizes them in a line divided into several sections:

Each row of the divided line represents a different category of thought. Let’s explore the hierarchy of these categories in more detail.

(Shortform note: Plato’s earlier dialogue The Symposium describes a more specific kind of “ascent” that is similar in some ways to the divided line. In a passage scholars call “the ladder of love,” he talks about how to “ascend” one’s appreciation and desire for beauty. Much like the divided line, the ladder of love ascends from the specific and concrete to the abstract and universal. Someone at the bottom of the ladder desires specific beautiful things but doesn’t necessarily know what makes them beautiful, while someone at the top understands the nature of beauty and desires it in all its forms. Keep this contrast between specific examples and broad concepts in mind as you read through the description of the divided line.)

Lowest Level: Illusions and Images

Illusions are beliefs not backed by evidence. Socrates says these are therefore the lowest form of knowledge, as very little suggests they’re true. For example, the popular idea that “sunflowers always point toward the sun” is an illusion; it’s commonly repeated and believed even though it has little to no evidence behind it. Socrates compares illusions to our perceptions of images or shadows in the world around us—you see your reflection in a mirror, but there isn’t another real copy of you behind or within it.

(Shortform note: According to Plato, art also falls into the category of illusion because it merely represents objects in the world like a reflection or shadow. However, Plato’s relationship toward art and poetry in particular is complex; on the one hand, he often discusses the dangerous moral influence of art. On the other hand, Plato’s own works are dramatic and often use allegories, myths, and other artistic or poetic devices. Some scholars suggest Plato does so to paraphrase and simplify his more complex points. Or, to use the language of the divided line, he offers illusions as a shorthand for concepts he understands on a deeper level.)

Second Level: Opinions and Objects

Opinions are beliefs backed by evidence. They’re therefore superior to illusions but still don’t provide concrete knowledge. For example, there’s plenty of evidence that gravity exists, but we can’t be certain it does or that it always will. Socrates compares opinions to our perceptions of physical objects. We can see and touch a table to see if it’s there, but those perceptions are still founded on assumptions—that we know what a table is, that our faculties are working correctly, and so on.

Opinions, Objects, and the Limits of Perception

Plato describes the first two levels of the divided line in terms of sense perceptions—illusions are false perceptions, while opinions backed by evidence and perceptions of objects are generally reliable. However, he still believes perceptions are inherently limited, which is why they make up the lower half of the line. To further understand why, we can turn to 18th-century Scottish philosopher David Hume. Hume famously argued that there’s no rational foundation for knowledge. In other words, he believed nothing was definitively provable because all human knowledge and reasoning rested on unreliable empirical evidence.

For example, imagine you hold up a pencil and then drop it. You would expect it to fall and would most likely be correct. However, there’s no way of definitively knowing the pencil will fall before you drop it. You can drop thousands of pencils and gain overwhelming empirical evidence that pencils fall when dropped, but evidence alone won’t prove that pencils always fall when dropped. This is why something like gravity—typically accepted by modern society as a fact—still counts as an opinion according to Plato’s theory.

Hume argues that all forms of thought ultimately rely on empirical evidence, as even logic like two plus two equals four relies on our perceptions of cause and effect. On the other hand, Plato believes there are types of thought that are independent of empirical evidence and its limitations—types of thought that are therefore higher on the divided line than opinions and objects.

Third Level: Knowledge and the Forms

Knowledge is provably universally true and unchanging. Socrates explains that we can arrive at knowledge through mathematical and philosophical reasoning. For example, we can use mathematical reasoning to prove that two plus two always equals four and will never stop equalling four. Therefore, we know that two plus two equals four. Similarly, Socrates suggests that philosophical reasoning and debate can provide provable, universal, and unchanging definitions of concepts like justice and beauty.

Socrates explains that knowledge is to thought as forms are to reality. The forms, he explains, are unchanging, universal, perfect versions of objects and concepts that exist in a separate realm. Objects imitate or derive from these forms in the same way that images derive from objects. For example, we understand what a perfect circle is in theory, but all existing circles in the world have flaws, however minuscule, that make them imperfect. The theoretical perfect circle is the form of a circle, and existing circles all derive from that form. All objects—from tables to fish to rocks—derive from their corresponding forms. They can also derive from the forms of concepts—a beautiful table derives from the form of beauty, for example.

Problems With Forms

To better understand how the theory of the forms works, we can look at how Aristotle—another ancient Greek philosopher and Plato’s student—argued against it. Here are two of Aristotle’s most significant critiques of Plato’s idealized forms:

1) Forms can’t create objects. According to Plato, forms cause the existence of objects. But Aristotle argues that if forms are eternal and unchanging, they can’t cause anything—in fact, they can’t do anything at all. Any kind of activity or motion would require the forms to change in some way, even if it just meant briefly changing from “not currently creating something” to “currently creating something” and back.

2) The “third man” argument, which is as follows: John is a man. All men derive from the form of a man—a perfect, unique ideal of man-ness. We’ll call this form Frank. Since Frank is the perfect ideal of a man, he himself is naturally a man as well. But as previously stated, all men derive from the form of a man. So if Frank is a man, he must derive from some even more perfect ideal of man-ness—some third man that both John and Frank can derive from. This logic loop extends indefinitely.

Highest Level: the Form of the Good and the Sun

Socrates argues that all forms—and the objects and images that derive from them—derive from the form of the good. Since the forms are perfect ideals, they must be good. You wouldn’t call a perfect circle a bad circle, for example.

Moreover, knowledge—the way we determine what is true and how we grasp reality—comes from an understanding of the forms. Therefore, the form of the good is the ultimate source of all knowledge and truth. Socrates compares the form of the good to the sun: Just as the sun provides the warmth for things to grow and the light for us to perceive them, the form of the good provides the reality for us to study and the truth for us to make sense of it.

(Shortform note: The form of the good and the sun strongly influenced early Christian theology and philosophy, with theologians connecting Plato’s theories to their understanding of God. For example, early Christian theologian Saint Augustine rejected the idea of a material, physical God after studying Platonic philosophy. Instead, he argued that God was an immaterial being responsible for creating the material world—much like how the form of the good is an immaterial concept that creates reality.)

Allegory #3: The Cave

After explaining the superiority of philosophical character and philosophical knowledge, Socrates describes how these elements combine to create an ideal ruler. He does so through an allegory of a cave, which describes the education and leadership of the ideal city’s philosopher-ruler.

Inside the cave, people are restrained so they permanently face the back wall. A fire is lit behind them, and various items are placed in front of it to project shadows on the wall. Because they’ve never seen anything else, the people in the cave believe these shadows are actual real objects. But one day, a man frees himself from his restraints, turns around, sees the items in front of the fire, and realizes the shadows are just images cast by them. Then, as his eyes adjust to the light, he’s able to ascend from the cave, see reflections and objects outside, and then eventually look up to see the sky. There, he’ll finally see that the sun provides the necessary light for all objects and shadows to be visible.

If he returns to the cave, his eyes will struggle to adapt to the darkness, and everyone inside will assume he’s delusional if he tries to explain what he’s seen outside. While he would prefer to spend all his time outside and see the true world, he knows he must return for the good of everyone in the cave—his community. When he does, he’ll understand the shadows far better than anyone else inside because he’s seen the objects that create them. He’ll therefore be far better suited to educating and guiding everyone else.

(Shortform note: A simpler, more modern way to understand the imagery of the cave is as a movie theater. Much like the cave, a theater is a dark, enclosed space where only projections are visible. Someone who had lived their entire life chained to their seat facing the screen would only experience the world through movies. Therefore, they would assume the objects and people on screen were real and not just a projection. But if someone could exit the movie theater into the light of day, they’d be able to see that movies are just images of real objects.)

Understanding the Cave

Combined with an understanding of the divided line, the allegory of the cave represents the role of a philosopher-ruler in society. In mundane society, people are focused entirely on conventional wisdom and worldly affairs like wealth and petty politics—just as people inside the cave are focused on shadows.

But those with a philosophical character find worldly affairs insufficient to explain the nature of the world around them. In the ideal city, they’re selected from the protectors and educated to become philosophers. This education mirrors the ascent from the cave, going from basic, universal education (illusions and objects) to mathematical reasoning, philosophical reasoning, and the form of the good (the sky and sun). This process lasts several decades, allowing the philosopher-ruler’s mind to adjust to this new understanding of reality just as the cave man’s eyes adjusted to the light.

Because of their love of knowledge, the philosopher-rulers will want to keep studying the forms indefinitely. However, they’ll recognize that they must rule because they’re best suited to the task—refusing would be placing their desires over the well-being of the city as a whole. Therefore, they’ll “descend” back into the cave to educate those still within it about the best, most moral ways to live their lives and run society.

(Shortform note: The themes presented in the cave and divided line of ascent and descent are central to The Republic and appear throughout the work. Descent or down represents movement toward the more worldly and less real, while ascent or up represents movement toward the real and abstract. For example, in the first line of the dialogue, Socrates says he went down to the Piraeus. The Piraeus was the port of Athens, a location associated with commerce and wealth. Therefore, Socrates is essentially descending into common society to educate people there about the true nature of reality—in other words, he descends back into the cave to tell those within it about the outside world.)

Part 4: Inferior Cities (Books VIII-IX)

Once Socrates has described the nature of the ideal city, he acknowledges that it will inevitably deteriorate over time. He explains that in the world of objects, change is inevitable. Since the city is already perfect, any change will be negative—and even the smallest negative changes will eventually accumulate into a broader decline.

Socrates describes this decline in terms of four inferior cities, each worse than the last:

1. Timocracy: a society structured around honor and ambition
2. Oligarchy: a society structured around wealth
3. Democracy: a society structured around personal freedom
4. Tyranny: a society structured around oppression and mob rule

In addition, he offers a personality representative of each, just as the philosopher-ruler represents the values of the ideal city. This continues his analogy of justice in society and justice in an individual. Part 4 of our guide will explain the nature of each inferior city and man, how they come to be, and why they’re inferior to the ideal city or philosopher-ruler.

(Shortform note: Many scholars interpret this section as Plato’s acknowledgment that the ideal city is not and cannot ever be real—he says that like all worldly things, the ideal city must decay. To him, ideals exist only in the realm of the forms where things are forever perfect and unchanging. However, it’s up for debate if Plato believes the ideal city is worth striving for in real life, or the extent to which he believes societies should try to emulate it.)

The Representatives of The Republic

Some scholars argue that the young men Socrates speaks with throughout The Republic correspond to the various city representatives Socrates describes. These scholars also suggest that Socrates is able to “elevate” these men by educating them about justice and the philosophical life, causing them to start acting like the next highest level representative—from oligarch to timocrat, for example. This elevation matches Socrates’s overall mission of providing the next generation of rulers with an education that will make them wiser and more just.

Throughout Part 4 of the guide, our commentary will discuss which character matches which representative and how Socrates is able to elevate them.

Step #1: Timocracy

A timocracy is a society where politics revolve around military prowess and honor, explains Socrates. In a timocracy, military and political offices are the same, and rulers are judged by their military successes.

The ideal city starts becoming a timocracy when, by chance, there’s a generation of less competent rulers and protectors. They’ll provide inferior education to the next generation, starting a cumulative decline. This eventually leads to rulers and protectors who venerate the physical and military ideals of the city but lack philosophical knowledge. Without this knowledge, they can’t understand who belongs to which class. Incorrectly assigning citizens will cause civil strife, and the timocratic rulers and protectors will have to enforce stability through violence and oppression against the workers.

(Shortform note: Plato directly references Sparta with his description of timocracy. Sparta’s culture highly valued military service and prowess in battle, and its society consisted of a relatively small aristocratic elite holding a much larger number of slaves. Spartan society was also obsessed with tradition. Plato seems to admire the Spartans quite a bit—more so than the democratic society of Athens (we’ll discuss democracy later)—given how close he puts their society to the ideal city.)

The Timocratic Man

Socrates describes the timocratic man as good-natured, conflicted, and ambitious. He wants to be excellent and values his physical and military training. His father—a philosopher—teaches him to avoid the corruption of public life and that goodness is reached through reason and knowledge. However, the rest of society judges his father harshly for his lack of military prowess and honor. The timocratic man tries to avoid this judgment while also maintaining some of his father’s principles. This middle ground between the desire for glory and the desire for goodness is ambition and a competitive drive.

The timocratic man also secretly desires wealth and the luxuries it provides. This is because his inferior education never convinced him that wealth corrupts—it just forced him to give it up.

(Shortform note: Some scholars argue that Glaucon represents the timocratic man, noting how Plato repeatedly emphasizes his bravery and military prowess throughout The Republic. In addition, Glaucon is the most closely associated with Socrates of all the other characters—the dialogue starts with him and Socrates together. Viewed from this perspective, Socrates spends The Republic attempting to elevate Glaucon from timocrat to philosopher by proving to him the value of a just, philosophical life. Whether or not Socrates succeeds is a topic of debate among scholars, as there are few surviving records of Glaucon’s later life.)

Step #2: Oligarchy

An oligarchy is a society where wealth is equal to political power, explains Socrates. In an oligarchy, wealth is equated with goodness and is a requirement for ruling.

A timocracy becomes an oligarchy when secret desires for luxury cause timocrats to continue accumulating wealth. As they do, they become less interested in personal excellence and more interested in managing their riches. This eventually erodes and then reverses their belief that wealth is corrupting. Oligarchies often have incompetent rulers, as wealth doesn’t translate to political skill. In addition, the sharp divide between rich and poor in an oligarchy creates further civil strife as the poor become vagrants and criminals.

(Shortform note: Oligarchy likely would have been the most common type of government during Plato’s time, as many ancient Greek city-states were run by a select group of wealthy aristocrats. However, not many historical accounts of these societies have survived. This makes it difficult to know if Plato’s description of oligarchy is based on other city-states or on periods of oligarchy during the history of Athens.)

The Oligarchic Man

According to Socrates, the oligarchic man is only concerned with making money. A political scandal or failure destroyed the life of his father—a timocrat. In an attempt to avoid poverty and misery by any means necessary, the oligarchic man abandons his moral principles and directs his ambition exclusively toward gaining wealth. He’s only honest when it benefits his reputation as a businessman and only restrains his hedonistic desires out of stinginess. In addition, he’s not courageous and gives up easily since he has to abandon any pursuit that might lose him money.

(Shortform note: Scholars argue that Adeimantus is the oligarchic man at the start of the dialogue, noting his repeated concerns early on about the material possessions of the ideal city’s ruling class. As the dialogue progresses, however, he becomes braver—calling out Socrates when he has questions and engaging more directly in debate. This newfound bravery suggests Socrates has elevated Adeimantus to a timocrat.)

Step #3: Democracy

A democratic society is defined by equal rights, freedoms, and political opportunities for all citizens, Socrates explains. In a democracy, people are free to live however they choose. Because of this, democratic societies have a lot of different ideas and perspectives.

An oligarchy becomes a democracy when younger generations spend their wealth extravagantly and without restraint. This is inevitable because maximizing profits requires enabling immoral behaviors—there’s money to be made not only in selling extravagant luxuries but also in exploiting the financially reckless. This also increases wealth inequality even further until there’s nothing but the desperately poor and the pampered, incompetent rich. When civil strife from inequality boils over, the poor revolt, overthrow the oligarchy, and grant everyone equal rights and opportunities.

(Shortform note: Plato’s conception of democracy is specific to the democratic society of ancient Athens. Under this system, all male citizens of Athens could vote on every law and issue directly as opposed to electing representatives to make laws for them. Athens became democratic in 507 BCE after a popular revolution overthrew an oligarchical regime—a historical event that matches Plato’s description of how democracy comes about.)

The Democratic Man

Socrates describes the democratic man as flexible but unprincipled. His father—an oligarch—teaches him to be stingy, make money, and avoid unnecessary expenses. But others around him in society indulge in extravagance and excess, and the democratic man gets a taste for luxury from spending time with them. They tell him this extravagance is the best way to live, and the democratic man believes them because he hasn’t been taught strong moral principles. And so the democratic man takes a middle ground between his father’s views and his society: He doesn’t constantly indulge in excess but he’s not stingy either. He’s also unwilling to judge those who indulge or say any pleasure is good or bad.

(Shortform note: Scholars argue that Polemarchus begins as a democratic man. They note how at the start of the dialogue, he convinces Socrates to discuss justice by pointing out that he’s outnumbered by young men who want him to stay—associating him with majority rule. As the dialogue progresses, Polemarchus becomes more reserved and has Adeimantus present his arguments for him. Thus, Socrates has elevated him to the more private and austere oligarchic man.)

Step #4: Tyranny

Socrates says a tyrannical society is governed by mob rule, violence, and oppression. It’s run by a single charismatic leader—a tyrant—who appeals to the people but only cares about himself.

A democracy becomes a tyranny through conflict between the rich and poor. In a democracy, the rich and poor have equal rights and freedoms but unequal wealth. Therefore, a charismatic leader can mobilize the poor by promising to persecute their enemies and redistribute wealth. Using the legal system and mob violence, this leader eliminates their political opponents and secures their power. They can then use wealth seized from the rich to hire a private army and oppress the masses for their personal benefit.

(Shortform note: Plato wrote The Republic not long after the end of a tyrannical regime in Athens. After Athens lost the Peloponnesian War to Sparta, the Spartans disbanded Athenian democracy and installed the Thirty Tyrants. The Thirty ruled with violence and fear, killing a large portion of the Athenian population and seizing their belongings. Plato grew up during the rule of the Thirty, which strongly influenced him—hence his dedication to educating the future leaders of Athens in philosophy to prevent something similar from happening again.)

The Tyrannical Man

According to Socrates, the tyrannical man is ruled by his violent, animalistic desires. His father—a democrat—teaches him that indulging in pleasure is OK if he practices moderation. On the other hand, his society teaches him to indulge extravagantly as much as he likes. And since his father refuses to judge people for indulging in pleasures, he doesn’t stop the tyrannical man from giving himself over to his desires. The tyrannical man spends his time having wild orgies, getting drunk, and eating to excess. When he runs out of money to feed his habits, he lies and cheats to get more. If that fails, he robs and kills people.

(Shortform note: Scholars suggest that Thrasymachus represents the tyrannical man, as he argues early on that might makes right and the strong should take whatever they desire. After his initial argument, though, one of the only times Thrasymachus speaks is to cast a vote along with the others on the group’s next topic of discussion. This behavior suggests that Socrates has elevated Thrasymachus to a democratic man.)

Part 5: Answering the Challenge (Book X)

After outlining the nature of just and unjust societies and how they correspond to individuals, Socrates returns to the original challenge: proving that a just person lives a better life than an unjust person. To answer this challenge, he shows how the philosopher-ruler—the representative of the perfectly just city—is better off in life and death compared to the representatives of the inferior cities.

(Shortform note: While Plato answers The Republic’s major question, this isn’t always the case in his work. Only some of Plato’s dialogues—specifically ones written during his “middle period,” which includes dialogues like The Republic and Symposium—provide accounts of Plato’s specific beliefs. The others end on an ambiguous note with the characters failing to find any answers. Scholars suggest that during his middle period, Plato began to develop philosophical theories independent of Socrates’s more ambiguous style. This may explain his shift in style.)

The Preferable Life

Socrates argues that the philosopher-ruler lives the best life of the individuals he has described. Because the philosopher-ruler has the most knowledge and best understanding of the world, he knows which pleasures in life are greatest and which are fleeting or lead to future pain. He prioritizes the pleasure found in pursuing and obtaining knowledge, which is the most real and permanent kind of pleasure—after all, it involves the true and unchanging forms. But he also allows himself to enjoy physical pleasures or the pleasure of being honored when appropriate.

The other individuals Socrates describes have less knowledge and therefore are worse at choosing which pleasures to pursue. This means they’re more likely to choose fleeting pleasures or pleasures that lead to pain. They also neglect the pleasure of obtaining knowledge in favor of other, less real pleasures. The further a man is from the philosopher-ruler, the worse pleasures he pursues and the worse his life will be. For example, the tyrannical man described earlier pursues the most fleeting pleasures—food, drink, and sex—even as it leads to pain in the form of violence, drunken madness, death, and so on. He therefore leads the worst life.

(Shortform note: Later ancient Greek philosophers expanded on the idea that pleasure is the measurement of a good life, elevating the pursuit of pleasure above all else. For example, Greek philosopher Epicurus (341-270 BCE) argued that pleasure was the primary good in life. He believed that people should try and minimize distress and negativity in their life in favor of pursuing pleasures. Similar to Plato’s argument, this meant picking and choosing pleasures that wouldn’t lead to further pains—as a result, Epicurus ultimately supported a lifestyle of moderation.)

The Preferable Afterlife

Socrates finishes by explaining that regardless of how fortunate or unfortunate someone is in life, justness is rewarded after death. He illustrates this principle with a myth about a man named Er.

(Shortform note: Plato’s dialogue Meno elaborates on his theory of life after death. In Meno, Plato describes life after death somewhat like reincarnation, where a soul exits and reenters various bodies as they die and are born. While a majority of memories are lost during this transfer, some essential knowledge remains. Importantly, the ancient Greek understanding of the soul is different from our modern definition—to them, “soul” is closer to our idea of “mind” or “consciousness.”)

The Myth of Er

According to Socrates, Er was a man who died in battle only to return to life 12 days later. He explained that while dead, his soul and many others were judged for their actions. The just were rewarded for their deeds in life while the unjust were punished. Then, the souls chose new bodies to inhabit for their next lives—human or animal.

Wise, good souls knew which lives would be good and chose accordingly. Some of the unjust learned from their mistakes and chose better lives, while others refused to admit they were at fault and chose lives just as bad as their previous ones. On their way back to earth to live their new lives, they drank water of forgetfulness and lost all memory of their ordeal—save for Er, who was told to return to his body and tell everyone what he’d seen to encourage them to live better lives.

(Shortform note: Some scholars argue that the myth of Er is something of a “noble lie” itself. They suggest that while the philosophy of The Republic argues for the value of justice in detail, the myth of Er offers the same moral truth in a much simpler-to-understand way. Therefore, it can still be morally true even if it isn’t literally true. Plato’s other dialogue Phaedo says this more explicitly. In it, Socrates describes a version of the afterlife similar to the myth of Er and then suggests the precise details don’t really matter—what matters is that they believe it’s true. This will encourage them to improve themselves and live good, just lives.)