Plato

18 May 2025

Sophist

Parmenides, a forefather of the tradition that Plato is engaged in, is quoted in the Sophist as advising people to avoid trying to show the existence of non-being, because such a task is doomed from the start. What Parmenides means by this is that, because being has to do with things that exist, non-being has to do with things that don’t exist. You can’t prove that things that don’t exist do exist. In a classic case of disobeying one’s elders, Plato goes against Parmenides’ advice and, by using the concept of motion, proceeds to prove the existence of non-being. The proof goes roughly as follows:

  1. Things are either in motion or at rest.
  2. Rest and motion don’t mix.
  3. Since we are talking about non-being, we have to talk about being.
  4. Being applies to both motion and rest.
  5. Being can’t be motion or rest, because if it were (for example, rest), then motion would participate in rest, which is impossible.
  6. We now have three categories: being, motion, and rest.
  7. Being is the same as itself and different from motion and rest.
  8. Rest is the same as itself and different from motion and being.
  9. Motion is the same as itself and different from rest and being.
  10. We have used “the same” and “different” to categorize being, rest, and motion. Which categories do “the same” and “different” belong to?
  11. “The same” and “different” must be their own categories. For example, if “the same” were motion, then point number 9 would say “Rest is motion, which is different from motion and being,” which is impossible.
  12. We now have five categories: being, motion, rest, the same, and different.
  13. Building on point number 8: If being is different from motion, then motion is different from being.
  14. This is the same as saying “Motion is non-being with respect to being.”
  15. Motion exists, and it is not being.
  16. Non-being exists, and it is difference—not the opposite of being—thus refuting Parmenides’ claim.

Statesman

The Statesman is an example of how to define a scientific field. The Eleatic Stranger and a young Socrates have gathered to discuss an area of science: the science of the political. The classification of political science goes as follows:

The division between the theoretical and practical is akin to the division between knowledge work and manual labor. The individual contributor is engaged in knowledge work that does not need to be passed off to others, while the manager does. The mathematician is an individual contributor, while the statesman is not, so we climb down the “Manager” node on this tree of science:

The tree in Plato’s text is more detailed than the one displayed here, but we see that the division has been made between middle management and upper management. Middle management passes on instructions from elsewhere, while upper management forges and passes on their own instructions. A prophet who passes on the instructions of God to the people is middle management.

Following the none of the “Upper Manager”, we see that this science divided into the work of the master-workman and herdsman: the management of non-living things and living things, respectively. Notice, as we go farther down the tree, the more the lines between a practical science and a theoretical science are blurred. The mathematician only needs to worry about abstract objects, but a master-builder, such as an engineer, has to be concerned with the actions of the beings he’s controlling in order to be successful. This applies to the herdsman and, with that, the statesman.

Reference: Method and Metaphysics in Plato’s Sophist and Statesman

Philebus

In the Philebus, the discussion centers on which way of life is better: the life of the mind or the life of pleasure. To begin answering this question, Socrates first divides all existing things into three categories: the infinite, the finite, and a composition of the infinite and the finite. There is difficulty in understanding the third category during the discussion, so Socrates begins to talk about how everything that comes into being has a cause. This cause of the composition of the finite and infinite becomes the fourth category. Socrates ultimately shows that pleasure belongs to the first class and mind belongs to the fourth class. He then concludes that a life combining mind and pleasure is better than a life consisting solely of mind or solely of pleasure. Even though a good life requires both pleasure and knowledge, we still need to determine how to rank them. Does a good life require more pleasure than knowledge, less pleasure than knowledge, or should they be distributed evenly? If we look into knowledge, we see that there is a science of measuring and counting. This science, the dialectic, which is akin to mathematics, is closer to truth, in terms of clearness and correctness, than all the other sciences. In the end, the ranking is as follows:

  1. Dialectical science
  2. The beautiful
  3. Wisdom
  4. Arts and non-dialectical sciences
  5. Pleasure

Timaeus

Timaeus weaves together the natural and the supernatural sciences to provide an explanation of how the universe was created by a creator. This creator believed that all things should be ordered and good, like himself. The creator looked around and saw only disorder. He brought order by using fire, air, and water to create immortal and invisible souls. He then created visible bodies, such as the planets, moon, sun, and stars, to house these souls. Next, he created gods and instructed them to create people, whose souls are a mixture of the mortal and the immortal. Each person was assigned a star, and if they lived righteously, they would return to their star. If they lived unrighteously, they would be reincarnated as a non-human animal. If the person lived unrighteously, they would be reincarnated as a bird if they were light-minded, as a fish if they were ignorant, or as a non-human animal if they lacked philosophy.

Critias

Critias says that anything that can be said is only a representation. When we describe mountains, stars, trees, and other things, we grant these descriptions some slack because we don’t really know these things well enough to criticize how accurately the descriptions represent the real thing. The descriptions can’t be obviously wrong, and we can say, “Yeah, that’s pretty close to a tree.” This slack can’t be granted to descriptions of human beings because we are human beings ourselves. This makes us much more perceptive of interpretations of humans in a way we wouldn’t be for descriptions of other things. This is why Critias asks Socrates to indulge him in his interpretation of the Ancient Athenians and Atlanteans. What does this interpretation of these two civilizations entail?

Well, 9,000 years ago, different gods governed different portions of land. One portion was governed by Hephaestus and Athena, who loved philosophy and art. They gave this land its laws, which led to it being a well-governed city, but it was unfortunately washed away by rains and earthquakes. The remnants of that city can still be seen, for example, in the small streams left over from the fountain that was in the Acropolis. These Ancient Athenians were well known all over the world for their beauty and wisdom.

Poseidon’s portion of land was Atlantis. It was ruled by kings who met every few years and passed judgment on their citizens based on the laws handed down by Poseidon. Atlantis had wealth in abundance, and all its citizens lived in harmony according to law. But their human nature started getting the upper hand, and Zeus noticed that this was the beginning of their downfall. Zeus decided to punish them in order to help them remember their roots. Zeus gathered the gods together, and they decided that Athens and Atlantis should go to war.

The dialogue is cut short before we hear Socrates’ response to this interpretation.

Apology

A 70-year-old Socrates is put on trial for corrupting the aristocratic youth of Greece. The young, wealthy men do not have to work and thus have a lot of time on their hands to listen to a man who questions the essence of things like truth, justice, and knowledge. Interestingly, his prosecutors cannot seem to point exactly to why what he is doing is wrong. There are some vague accusations of him being an atheist, which Socrates disproves by showing that he believes in spiritual agencies and thus cannot be an atheist. It seems that the government is simply annoyed by his questioning. They are even more annoyed that the youth are imitating him.

A god once declared that Socrates was the wisest of men. In order to prove the god wrong, because he did not believe he was the wisest, Socrates went around town interviewing politicians, artisans, poets, and rhetoricians in a quest to find people wiser than himself. During these interviews, he learned that these people are not wise because they do not question the essence of things. Socrates does himself no favors when he calls out these people for not being wise, especially by doing so in front of their friends, thereby embarrassing them. But the state did not put him to death for simply being antisocial; he could not have been the only annoying person in Greece at the time! The state correctly perceived that the sort of questioning Socrates was engaged in was a threat to society and it had to be stopped by first making an example of its master.

Charmides

Socrates interviews a young Charmides to discern whether he possesses wisdom. But what is wisdom? Wisdom is self-knowledge and is the essence of knowledge. Since wisdom concerns knowledge, it must be a science. But what is the subject of this science? Apparently, it is the science of itself, the science of other sciences, and the science of the absence of science.

Wisdom is unique among the sciences because other sciences are about things other than themselves. For example, architecture is the science of building design, not the science of architecture itself. This distinction suggests that we cannot treat wisdom as we do other sciences.

Whether such a science is possible is a question left for future inquiry. Even if such a science exists, we must ask whether it benefits us and thus deserves to be called wisdom, since wisdom ought to be advantageous. Wisdom, understood as self-knowledge, cannot itself teach other sciences, so it offers no direct advantage there. The only possible benefit is that, by knowing what we know and do not know, wisdom might make it easier to learn other sciences. Beyond that, it’s doubtful that Charmides will gain any advantage in life from having wisdom

Crito

While Socrates is in prison awaiting his execution, his friend Crito attempts to persuade him to escape. However, Socrates refuses, and he explains his reasoning as follows:

Since the state is injuring Socrates by condemning him to death, does that mean he should injure the state by breaking its laws? (Here, the law being broken would be escaping from prison.) Socrates answers “no,” because breaking the law would be doing evil. If a law is unjust, one should seek to persuade the state that the law is unjust, rather than harming the state by disobeying its laws.

Therefore, Socrates must die as the Athenian laws command, if he wishes to remain a good man rather than become an evil one, as reason demands.

Euthyphro

Euthyphro is prosecuting his father for murder. The case involves Euthyphro’s father leaving a field laborer who had killed a domestic servant in a ditch while awaiting guidance from religious authorities on what should be done with the laborer. During the wait, the laborer died of exposure, prompting Euthyphro’s charge.

Meanwhile, Socrates faces accusations of impiety. Curious about Euthyphro’s confidence in his own piety for prosecuting his father, Socrates seeks to learn the essence of piety and impiety from him.

Euthyphro initially claims that piety is exemplified by his own action: prosecuting his father for murder. Socrates finds this unsatisfactory, as citing examples does not reveal the underlying nature of piety. When pressed, Euthyphro defines piety as doing what pleases the gods and impiety as doing what displeases them. Socrates points out that the gods often disagree, so the same act could be considered pious by some gods and impious by others. For instance, Zeus might approve of Euthyphro’s prosecution because Zeus prosecuted his father, while Cronos, having been persecuted by his own sons, would not.

To resolve this, Socrates suggests that piety is what all the gods agree upon. With this new definition, the authority of piety shifts from the gods to their consensus, implying that piety exists independently of the gods. Once cornered into implicitly admitting that the gods don’t have authority over piety, Euthyphro is no longer interested in the exercise. He decides to leave, and Socrates fails to get to the essence of piety through Euthyphro.

Gorgias

Gorgias, a professor of rhetoric, attempts to define his craft. His craft is the art of persuasion, aimed at the public. Rhetoricians need not be experts in the subjects they discuss. With their oratory skills, they can convince the public of anything. In fact, they are often able to persuade the public on matters outside their expertise even more effectively than the experts can. For example, Gorgias recounts how he was able to convince a patient to take his medicine, despite the doctor’s inability to persuade the patient.

If rhetoricians have the power to convince the public of anything they wish, what prevents them from engaging in fraud? There must be some form of ethics governing rhetoric, or else Greek society would not have held the profession in such high esteem. Unlike Socrates, Gorgias does not try to ground his ethics. He claims that as long as rhetoricians do not damage the expert’s reputation, they are not misusing their powers. According to Gorgias, if the patient continues to regard the doctor as reputable after encountering the rhetorician, no harm has been done. The protection of experts’ reputations guards society from rhetoricians who might otherwise convince the public of anything they please. If rhetoricians do their job correctly, the public should remain aware that it is the experts who truly possess knowledge.

Hippias Minor

Out of Homer’s two poems, the Iliad and the Odyssey, Hippias thinks the Iliad is the better poem. This is because the main character of the Iliad, Achilles, consistently aims to tell the truth but sometimes unintentionally lies. The main character of the Odyssey, Odysseus, on the other hand, intentionally lies.

Socrates thinks that Odysseus is the better man because he intentionally lies, while Achilles is the lesser man because he unintentionally lies. To Socrates, ethics is just another art, like archery. An archer who consistently misses the mark is better than an archer who accidentally hits the mark because the archer who consistently misses is so skilled that he doesn’t rely on chance. If he can consistently miss, then he could also consistently hit the mark if he so wished. The archer who accidentally misses is the lesser archer because it follows that he would also accidentally hit the mark.

It’s hard to argue with this logic, and Hippias doesn’t attempt to do so. He simply decides that he doesn’t agree with Socrates. Most of us would do the same. We know that someone who tries to do right but doesn’t hit the mark 100% of the time is better than someone who is so good at doing wrong that they never err at it. If a skilled evildoer decides to do right, they will perform better than the unskilled do-gooder. But for Socrates to call the skilled evildoer who has not converted to doing good the better person than the unskilled do-gooder is confusing unless Socrates is prioritizing the skills a person possesses over the consequences those skills lead to.

Meno

Meno wants to know how people gain virtue: Is it acquired through education or by some other means? Socrates admits that he does not know what virtue is and has never found anyone who could define it. Meno suggests to Socrates that virtue is a person’s ability to govern a household or a state. However, after some questioning from Socrates, it becomes clear that virtue is not merely the talent to govern; it can also include health, wealth, and other good things. There are many virtues, but Socrates, as always, is not interested in the particulars. He wants to discover the essence of virtue: a general definition that encompasses all particular instances.

When Meno claims that virtue is the desire for honorable things and the power to attain them, Socrates undermines his thesis by concluding that, according to this definition, everyone is virtuous since everyone desires the good. Meno then revises his position, arguing that virtue is not just the desire for the good but the ability to attain it. Attaining the good, however, must be done honestly, thus raising the question of what honesty is. Honesty is itself a part of virtue. Socrates and Meno become stuck in a circle; they cannot make progress in defining virtue because each definition implicitly contains virtuous qualities.

This cycle reminds Socrates of a myth that religious leaders preach. The myth goes as follows: When a person dies, their immortal soul travels to another world, where it acquires knowledge of all things. Upon reincarnation, the soul forgets what it learned in that realm. Therefore, learning is an act of recollection, remembering things the soul once knew but has forgotten.

To test this hypothesis, Socrates asks Meno’s slave a geometry question that the slave has never been taught. The slave does not know that (d^2 = 2a^2), where (d) is the length of the diagonal of a square and (a) is the side length. Nevertheless, through a series of questions posed by Socrates, the slave is able to discover this theorem on his own.

If geometry can be taught through questioning, then perhaps virtue can also be taught. This suggests that virtue may be a form of knowledge. However, Socrates doubts that virtue is knowledge because, if it were, it could be taught, and teaching requires both teachers and students. Yet, there is no one in Athens who can teach virtue. Socrates and Meno never fully succeed in Socrates’ mission, but they do make progress in answering Meno’s question. If no one can teach virtue, then virtue is not gained through education, but is instead a divine gift.

Phaedo

Phaedo tells Echecrates about the conversation Socrates had with his disciples on the last day before his execution. The context of the dialogue calls for a discussion on the philosophy of death.

The philosopher desires death because it separates his soul from his body. This is because the philosopher’s mission, to contemplate Ideas like absolute greatness, absolute smallness, is hindered by the body. However, even though the philosopher desires death, it should not be by his own hand, for the same reason that it is unlawful to escape from prison.

The soul is immortal and the body is mortal. Proving that the body is mortal is not hard, but proving that the soul is immortal is difficult. We must first prove that the soul existed before birth and also that it will exist after death. The soul’s existence before birth is sufficiently proved by the same methods employed in the Meno: one can observe that the soul learns subjects like geometry by remembrance of concepts it knew before birth but has now forgotten.

Proving the soul’s existence after death is difficult, but if one accepts the existence of Ideas, it should be relatively straightforward. Opposite Ideas coexist but do not exist in the same thing. For example Simmias is greater than Socrates and smaller than Phaedo, but he is not by himself greater or smaller; rather, he is greater or smaller relative to others. This concept also applies to things that are inseparable from their attributes. If cold and heat are opposed, then fire, which is inseparable from heat, cannot coexist with cold. It then follows that if life and death are opposed, then the soul, which is inseparable from life, cannot coexist with death. Therefore, the soul is immortal.

Phaedrus

Socrates and Phaedrus address two topics: love and rhetoric. Let’s focus on the latter. We saw in the Gorgias how rhetoric is often used to mislead. In Socrates’ time, there were people called rhetoricians, masters of persuasion. They could convince anyone of anything, and they didn’t care whether what they were saying was true. One day they could make something seem good, and the next, make that same thing seem evil. These people, often holding high political positions thanks to their persuasive skills, were respected members of society.

Socrates, being someone who cares about the truth, couldn’t see himself aligning with the rhetoricians. But he also wanted to persuade others. He rightly believed that his teachings would be useless if his audience couldn’t be convinced. So, he tells them that his rhetoric is rooted in truth. Socrates introduces the idea of the “Philosophical Rhetorician”, someone who has seen the truth and can then use rhetorical techniques to persuade. In fact, the Philosophical Rhetorician must know the truth to be effective at rhetoric, because the more someone understands the truth about their subject and about human beings, the better they are at deviating from it, if their goal is to convince others of something false. The responsibility, then, also falls on the audience: they must know the truth to protect themselves from being misled.

In our time, where knowledge is highly specialized, only a handful of people understand any given subject. It’s easy for experts to mislead, and it’s unreasonable to expect non-experts to guard against deception because they would need years of training in each of the subjects to be capable of discerning the truth. For example, an expert might claim that their science will bring enormous returns, wealth, power, for those who fund it, and the audience would be completely incapable of performing due diligence. Phaedrus doesn’t address this problem. For now, it seems like we first need to understand how people navigated persuasion before truth became the central concern so that we may learn from them.

Symposium

In the Symposium, Phaedrus, Pausanias, Eryximachus, Aristophanes, Agathon, Socrates, and Alcibiades each deliver a speech about love. Agathon and Socrates, unlike the others, who speak about the benefits that Eros, the god of Love has given them, and unlike Alcibiades, who confesses his love for Socrates, focus on the nature of Eros. Given that Agathon, the poet, does not prioritize truth, while Socrates, the philosopher, does, let’s concentrate on Agathon’s speech.

In summary, Agathon claims that, of all the gods, Eros is the best. He is the youngest: he was not yet born in the time of Homer. In those times, people acted out of necessity, not love. If Eros had been present then, violence would not have been rampant; instead, there would have been peace on earth. Agathon describes Eros as tender, just, graceful, temperate, and offers other beautiful praises. Here is the whole speech.

It’s an awe-inspiring speech, one that could convince most people that love is truly the greatest thing there is. But in what way is it not concerned with truth? Agathon does not make rigorous arguments to support his claims about Eros. He heaps words of praise upon Eros without explaining why Eros should possess these qualities.

Theaetetus

In the Theaetetus, Socrates poses the question: “What is the nature of knowledge?”. Theaetetus’ first answer is that the nature of knowledge is perception. If knowledge is perception, then each person has different knowledge. One person may feel that the wind is cold, while another person may perceive the very same wind as being warm. The Sophist Protagoras, summarizes this view: “Man is the measure of all things”.

If man is the measure of all things, then nothing is stable. One man might measure (that is, perceive) the wind as being cold, while another might measure it as warm. There is no stability in this measure, no external reference by which to claim what the wind really is. This means that the properties of the wind, and anything else that people might measure are in perpetual flux, a theory associated with the philosopher Heraclitus.

If everything is in flux, then it’s impossible for man to measure anything. A man is incapable of claiming that the wind is cold because the property of the wind is never stable; it changes depending on who you ask. If everything is in flux, nothing can be measured and thus there is no perception to be had because everything is chaos. If Theaetetus is basing his claim on Heraclitus’ doctrine, then he is incapable of maintaining that knowledge is perception without falling into a contradiction, for his claim ultimately implies knowledge is whatever anyone perceives it to be. It can be perception or it can be anything else. Socrates avoids this contradiction by asserting that a wise man, rather than every man, is the measure of all things.

References

  1. Stanford Encyclopedia of Philosophy: Plato on Knowledge in the Theaetetus.

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