Welcome to our third session on Plato's Theaetetus. We will be reading the dialogue through 183c today, and we are almost going to seal the fate of the idea that knowledge is perception, almost hammering the last nail into the coffin, but not quite. This has turned out to be a real can of worms that Theaetetus opened up with his simple claim that knowledge is perception.
To review where we have been: Socrates very quickly raised the question of what knowledge is, and Theaetetus's first answer was to list examples: astronomy, mathematics of various kinds, the crafts like cobbling. But that was not really an answer, since those were merely examples. His first real answer, according to Socrates, was that knowledge is perception. Socrates then links this to the saying of Protagoras, "Man is the measure of all things," that is, each perceiver is the measure of truth, and to Heraclitus, among others, who says you cannot step in the same river twice, that everything is flowing and changing. With a little more work, the idea is delivered, as it were, and now they are testing it.
I want to go back to the word "measure" in the saying that man is the measure of all things. If we say that this glass of water is seven inches tall, is that an objective fact? Is it a fact about the glass itself, without relation to anything else? For it to be seven inches tall, that is a relationship between the cup and a ruler that shows inches, so it would have to be relational. And there is also, at least implicitly, some relation to the measurer: someone had to look at it and determine that it was seven inches tall.
Is "seven inches" objective, then? We feel it is more objective than, say, "it is delicious water," something we would call subjective. But Protagoras would probably say that your so-called objective information about the thing in itself also depends on some relation to you; you have intervened in some way to obtain that so-called fact. We also discussed how in quantum mechanics we now believe that measurement actively intervenes and affects what is measured, at least at a certain scale. There seems to be something fairly deep about Protagoras's insight.
Combining Protagoras and Heraclitus, Socrates constructs a theory of reality, or rather of becoming, since he wants to avoid the word "being." Everything is in motion, motions are intersecting, and in these intersections we get momentary flarings-up of an appearance, a phenomenon, a good Greek word that simply means something that appears. It appears to someone and appears to be of something, but there is no thing that exists independently of the relationship. The perception is all there is, and there is no perceiver independently of that moment of intersection of the two motions. All of this rather bizarre understanding of reality emerged from the single idea that knowledge is perception.
We looked at a couple of objections, including a kind of ad hominem objection: if everybody's perceptions are true, then what makes your perceptions, Protagoras, any better than anyone else's? Why are you so wise? His answer was that he knows how to change other people's perceptions in order to make them better. We discussed how that answer assumes some standard of better, but perhaps that is not much of an objection, because Protagoras could reply that "better" simply means better by the standards of the person whose perceptions he is changing.
If people feel that their perceptions are more desirable after his intervention, then those perceptions are more desirable, for them. On this view, Protagoras deserves his high fees because he is the one who facilitated that improvement, whether as a therapist, a political counselor, or some other figure capable of reshaping others' perceptions.
Today, Theaetetus is going to get a well-deserved rest for a while, and it will be Theodorus who interacts with Socrates. Socrates almost coerces him into this, or at least shames him into it, saying, in effect: it is not my job to be defending your friend Protagoras while you simply sit there, and you would have me go on challenging a mere boy? Come on, you and I will do this together. Theodorus finally agrees, making the exchange more personal.
At 169a, Socrates makes the argument personal: "Come with me until we see whether in questions of geometrical proofs it's really you who should be the measure, or whether all men are as sufficient to themselves as you are in astronomy and the other sciences in which you've made your name." These are supposed to be genuine sciences, astronomy, geometry. How can Theodorus agree with Protagoras and maintain that everybody's perception of these things is equally valid? Theodorus ultimately gives in to what Socrates calls his terrible lust for these exercises, using the word eros, an erotic drive toward philosophical argumentation.
The first objection to Protagoreanism is essentially this: if everybody is right about everything all the time, then people are right when they disagree with Protagoras. There are various cases and details one could explore, but that is the basic idea. Does this demolish Protagoreanism outright?
Audience: There are different uses of the word "right." Someone can be advocating correctly for their own position, and there is a separate question of whether that position is accurate. It is possible for someone to be right in the sense of sincerely stating what they believe, while still being wrong in that what they believe may not match or may not be the best explanation for the set of facts they are trying to account for.
But would that really be Protagoras' defense, to say that his opponents may not be right about the facts? He would more likely say that in the moment they raise the objection, they are right for themselves. This should give us considerable confidence as we discuss Protagoreanism, since on his view we cannot be wrong. But seriously, when you encounter a relativist, and one often appears sometime around sophomore year of college, this objection naturally comes to mind: "You say everybody is right all the time? Well, I disagree with you, so you admit I'm right, which means you're wrong." Does that short-circuit the relativist position, or can the relativist find a way to shrug it off?
Audience: It's like explaining something to a child or someone just beginning to learn. You don't want to sound condescending, but the response is essentially, "You're right for you" — right for your stage of development.
Perhaps Protagoras' form of rightness claims to be a higher truth, a more sophisticated rather than sophomoric one. Does he have the right to claim that his truth is somehow superior? If he says everyone can be right, and someone replies, "Protagoras, I think you're wrong, so I'm right and you're right, yet we contradict each other," he might respond that his perception is more favorable — and as we discussed in the last class, that is what makes him wiser, though he would have to add "more favorable to me," since everything is relative.
This objection is not definitive — it is not the final nail in the coffin by any means. The relativist can always come back and say, "Sure, that's true for you, but not for me." You cannot pin him down to anything that will stand as absolute, because whenever you think you have him cornered, he will say, "Okay — for you." It is genuinely maddening. Socrates makes this point at some length, and it is worth sitting with how difficult it is to refute a thoroughgoing relativist on his own terms.
People disagree with Protagoras both directly and implicitly. They disagree implicitly whenever they trust certain experts over amateurs. Socrates points out, at 170A, that in emergencies — when people are in distress on the battlefield, in sickness, or in a storm at sea — when they truly have skin in the game and the stakes are real, they are not relativists. They will not turn to just anybody; they will seek out a doctor or someone they have reason to believe is genuinely expert in the relevant field. If everybody is right all the time, then they are right not to be relativists. Of course, Protagoras could still reply that their deference to experts is simply what is right for them at that moment.
This point about emergencies opens onto a broader discussion concerning prediction. Why, if you fall ill, do you turn to an MD rather than a faith healer? Because you want to live — and to keep living into the future. The real question, then, is what is actually going to work, and whether everyone is equally an expert on that. If we are permitted — and this may be a significant concession — to look beyond the present moment of perception and allow for predictions about future outcomes, then ordinary people in real life will consistently believe that some individuals are better predictors than others. This conviction carries substantial implications, not least for questions of politics.
Let's turn to 172A — page 41 in the Hackett edition. "Consider political questions. Some of these are questions of admirable and shameful conduct, of just and unjust, of pious and impious. Here, the theory — relativism — may be prepared to maintain that whatever view a city takes on these matters and establishes as its law or convention is truth and fact for that city. But when it's a question of laying down what is to the interest of the state and what is not, the matter is different." The distinction being drawn is between what is just or morally good versus what is prudent and strategically sound. Perhaps the first is relative; the second seems more objective.
This is, I think, a very modern distinction, as well as an ancient one. It resembles the fact-value distinction we commonly make today. I realized when I had a child in third grade that we actually train schoolchildren to make this distinction — this large metaphysical, philosophical distinction. They are given a list of statements and taught that if a statement contains the word "good," "better," or "beautiful," they are to mark it as opinion; otherwise, it is to be marked as fact. This is taken to be somehow written in stone.
I remember one example from Ohio: the statement was, "The Columbus Airport is the best in Ohio." The correct answer was opinion. This is modern dogma in many circles — whenever you express a preference, that is not actual knowledge; it is merely a feeling, something relative. But a statement like which airport has the most takeoffs and landings in a day — that is a fact. Are you comfortable with that distinction? Is it really written into the nature of things?
Audience: In my aesthetics class, we had an essay due, and my professor projected one of the essays he received on the board. The student had written, "This painting is objectively beautiful." He highlighted that and said he never wanted to see it again. Things like beautiful, best, and good can't really be objective.
That is according to your professor. But why should we trust this professor? According to Protagoras, we could all be right in our own sense. In any case, the distinction seems to come easily. Let's take a current example. In recent history, the US government abducted the president of Venezuela — and I am trying to describe that objectively with the word "abducted." Was this fair? Was it just? Was it justified by international law? Perhaps the legal question admits of an objective answer, but whether it was fair or good is, as we say, a value judgment. There will be different views on whether it was justified.
Was it in the interest of the United States? That seems more objective. We may not know yet, but potentially it could secure oil and economic gain — which is good for national prosperity, or so the argument goes. This is a very realistic point of view — Realpolitik, perhaps. And so Socrates says, "I see, Theodorus, that we're becoming involved in a greater discussion emerging from the lesser one." All sorts of large questions about justice are now being raised.
At 172c, Theodorus says, "Well, we have plenty of time, haven't we, Socrates?" The word he uses here is worth noting: scholē, which looks like "school" and is in fact the root of that word. It means leisure, free time. Socrates himself had already used the same idea back at 154e, remarking that they have plenty of leisure, and Theodorus is picking up on that. The remark provokes several pages of what Socrates himself calls a digression.
Socrates responds: "Well, we appear to. That remark of yours reminds me of an idea that has often occurred to me before — how natural it is that men who have spent a great part of their lives in philosophical studies make such fools of themselves when they appear as speakers in the law courts." On the surface, this seems to have nothing to do with knowledge, presenting itself as a pleasant break from the heavy-duty argumentation.
Notice how Theodorus reacts to this digression: he loves it. He says things like, "I like listening to this sort of thing — it is easier for a man of my years to follow." He also says, "If your words convinced everyone as they do me, there would be more peace and less evil on Earth." This reveals something perhaps relevant about Theodorus: he has little appetite for the nitty-gritty of philosophical argument, but he delights in flowery speech about how wonderful philosophers are.
Audience: Couldn't it also be called a speech about how useless philosophers are?
Indeed. The digression is really about the useless philosopher versus the useful so-called "lawyer" — and we should turn to the content of it with that framing in mind.
I put "lawyers" in quotes because the ancient Athenian legal system had no professional lawyers as we do today. Instead, there were orators who argued cases and helped citizens make their arguments. In theory, if you were brought to court and charges were laid against you, you had to defend yourself in person. You could have someone else write a speech for you — though in theory you could not pay them for it, even if that restriction was honored only in theory — but you still had to speak those words yourself. Athens also had no professional prosecutors and no district attorney. If you disliked what a fellow citizen had done, you simply brought them to court and argued the case yourself.
This was one way in which ancient Athens was radically democratic. In some respects Athens was less democratic than we are, since only a minority of people held citizenship — adult male native-born Athenians who were not enslaved — but that still amounted to a fairly large number of men. If you belonged to that group, you were constantly drawn into public affairs. You might be assigned by lot to serve on various governmental bodies, and you would frequently sit on juries of 501 men. Given that Athens was not a large city by our standards, jury duty was a regular part of civic life and of being an active citizen. Sooner or later, almost everyone ended up in court in one capacity or another.
Some men, however, were perpetually involved in litigation — knocking about the law courts their entire lives. These are the men we can reasonably call lawyers, since that is a close modern parallel. With that in mind, let us consider the qualities Socrates attributes to the philosopher and the lawyer respectively.
Audience: I think of the philosopher as more level-headed — when you see Justice depicted with her blindfold, it suggests a reluctance to pass hasty judgment.
That allegory of Justice is interesting. She is blind in the sense that she disregards irrelevant factors — race, class, and so on. But she does pass judgment, which is why she also carries a sword. One thing Socrates does say is that the philosopher is concerned with questions such as what is justice itself, whereas the lawyer is concerned with the injustice of this or that particular person in concrete legal terms. The philosopher asks the large, definitional questions — much as one might ask not merely how to repair shoes but what knowledge itself is — while the lawyer deals with specific cases.
Audience: Looking at 175E, Socrates describes the philosopher as living in freedom and leisure. He says the philosopher doesn't know how to make a bed or sweeten a sauce, so he isn't concerned with practical specifics — whereas the man who can sweeten a sauce or make a bed might not be able to compose a song or praise the gods appropriately.
That passage moves somewhat beyond lawyers in particular. Socrates is talking about people who get their hands dirty with concrete skills and crafts. There is a sneering tone to it — "sweeten the sauce" implies that being a chef is a lowly occupation. The philosopher, by contrast, is occupied with higher things and operates in a higher realm. Noble might be the right word to capture what Socrates is suggesting: the philosopher's concerns are simply more elevated than those of the craftsman or the career litigant.
Thales does fall into a well — but maybe that's a badge of honor. This is certainly the way the story presents it. It gives rise to the well-earned stereotype of the egghead with his head in the clouds: Einstein with mismatched socks, the nerd we all know. The original nerd was Thales.
Thales, historically considered the first philosopher, is famous for the statement that all is water — a radical simplification of everything down to its material basis. The story goes that he was studying the stars one night, walking around looking up at the sky, when he fell into a well. A Thracian servant girl laughed at him because he was so eager to know what was up in the sky that he failed to see what was right in front of him and under his feet.
This anecdote has been repeated many times throughout the history of philosophy, and the same joke is taken to apply to all who spend their lives in philosophy. The philosopher, in short, is a nerd.
The lawyer type is much more practical, but according to this speech, that is not a good thing. It means you are focused on tiny, momentary concerns and how to fix them. Leisure is how this whole digression began, so let us talk about that. The philosopher has scholē — free time — an expression that would carry enormous weight in a slaveholding society, where most people are simply working to stay alive, or are actually forced to work and have no free time at all. Their time belongs to somebody else. The philosopher, by contrast, is free: at least some of his time belongs to him, and he can devote it to what is intrinsically valuable.
What is the lawyer's relationship to time? He is crunched. We see this constantly in legal dramas, where the judge says, "Get to the point, Counselor." There is a fixed task and a fixed time in which to accomplish it. You have to be a clock-watcher.
Audience: There is a real cruelty here in some way — Theodorus says, "Our arguments are our own like slaves; each one must wait about for us." Taking for granted the ownership of people, and then using the ownership of an argument as a point of comparison, seems quite extraordinary in a dialogue that is also asking what justice is. You can really tell that this comes from a slaveholding culture.
That is a very interesting remark. Theodorus says this at 173c: "Our arguments" — logoi, an important word, as we will see later — "are our own like slaves; each one must wait about for us to be finished whenever we think fit." The lawyer, by contrast, is a slave to the arguments. I have friends who are lawyers, and I would never want to be one, because it does seem that you are truly enslaved to the letter of the law and to all the tasks imposed upon you — brutal, hard work. Whereas we philosophers get to talk about whatever we want, as we wish.
The main remaining point is to spell out all the things the philosopher is ignorant of — and blissfully so. He falls into wells; he is a nerd who does not know the way to the marketplace, the agora, does not know the way to the courts, knows nothing about politics or laws, and at 173d knows nothing about the family background of his fellow citizens: "He has no more idea whether a fellow citizen is high-born or humble, or whether he has inherited some taint from his forebears."
Audience: That seems like an overstatement. Earlier in the dialogue, Socrates mentions that Theaetetus came from a good family and was left an inheritance, so he does pay attention to these things.
Good catch. In fact, one of the very first things we see in the dialogue is Theodorus saying he has forgotten who Theaetetus' father is, and Socrates immediately replies, "Oh, yes — son of Euphronius of Sunium." So this is not exactly a self-description. Something odd is going on. Consider the other details as well. The philosopher supposedly does not know the way to the agora — and agora is the root of agoraphobia, fear of public spaces. The agora was not merely a marketplace for buying and selling; it was where citizens came together to see one another, the Times Square of Athens. Yet Socrates is famous precisely for hanging out in the agora. He did not teach in a school; he went out in public and interacted with his fellow citizens. He was certainly not agoraphobic.
The philosopher is also said never to go to parties. Yet in Plato's Symposium we learn that Socrates could drink everybody under the table — so he did go to parties. And here is what really clinches the point that something strange is going on. At 173a: "In all these matters, he knows not even that he knows not." He does not even realize that he is ignorant. Then at 174b: "The philosopher fails to see his next-door neighbor. He not only does not notice what his neighbor is doing — he scarcely knows whether the neighbor is a man or some other kind of creature. The question he asks is, 'What is man?'" He is asking what it means to be human as such, yet he does not even look at his own neighbor, and does not even realize that he does not know him. So: is this a self-description by Socrates or not?
Audience: He is going after the "man is measure" thesis. If the philosopher is already asking what a man is, then you cannot say man is the measure of all things, because you do not even know what a man is.
Excellent — I had not thought of it that way. We must ask: what is a man? What does it mean to be human? That is the question, and it is a very important one. However we read this passage, we should not conclude that it is simply a negative portrayal of the philosopher, because these are genuinely good questions — and who wants to be a lawyer anyway? But it is a poor description of Socrates himself, who, as we have seen, frequents the agora, attends parties, and knows perfectly well who his neighbors are.
As I've pointed out, the first thing Socrates says about himself in the whole dialogue is not that he's always asking what it means to be human, but that he's always asking where the promising particular humans in Athens are. He wants to know his neighbor, his neighbor's parentage, and all these concrete things. So what's going on here? He's creating a straw man figure of the Philosopher.
Audience: Why would he do that? Does he want to tear down philosophy?
No — I think he wants to tear down Protagoras, so he can come back at him and make a different argument. And would this portrait be more accurate as a description of someone other than Socrates whom we know?
Audience: Theodorus.
Exactly. I think what's going on here, at least in part, is that Socrates' picture of "the Philosopher" is a distorted picture — really more a portrait of Theodorus. At 173E, Socrates says the Philosopher's mind "pursues its winged way throughout the universe, in the deeps beneath the earth doing geometry of planes, and in the heights above the heaven doing astronomy." These are precisely the things Theodorus teaches, not Socrates' main focus. Theodorus loves this praise of the abstract philosopher because he doesn't realize it's a satire on him — thus proving Socrates' point that Theodorus lacks self-awareness and doesn't recognize when he's being made fun of.
But is that all it is — a cruel joke at Theodorus's expense? Is Socrates saying the opposite of what he seemed to say, that the Philosopher is great and the Lawyer is an idiot? Is he really saying we should be lawyers?
Audience: I'm trying to think whether either of these categories has knowledge. The Lawyer probably has practical knowledge, and the Philosopher has something like geometrical knowledge — the kind we see in The Clouds. Maybe he's going for something in the middle?
Yes, that's a promising suggestion — that if you could combine both forms of understanding, you would have something genuinely valuable. It's good that you mentioned The Clouds. That comedy by Aristophanes is one of our three main sources for Socrates — along with Plato and Xenophon — and in it Socrates is portrayed as a natural philosopher investigating the sky and the depths of the earth, even having himself carried up in a basket as if he inhabits the clouds. There's a clear echo of that here, along with Aristophanes' broader mockery of philosophy for being arrogant and prying into things that don't concern it.
There's also an interesting echo of the Allegory of the Cave, the famous passage in The Republic. Socrates asks us to imagine prisoners in a cave who have been shackled since birth, able only to stare at the wall. Behind them a fire burns, and between the fire and the prisoners, people walk back and forth carrying puppets whose shadows are cast on the wall. To the prisoners, those shadows are reality — they don't even realize they are shadows. If you were to set one prisoner free, turn him around, and push him toward the fire, he would be in pain, confused, and resentful. If you then dragged him out of the cave entirely and into the sunlight, which he has never seen, he would hate you even more, because everything would be blindingly bright. But with time he would adapt, learn to see things in the open air, and understand that this is reality — that everything in the cave was merely a derivative imitation.
Plato uses this ascent to represent the movement from the world of everyday tangible objects to the world of the Forms — abstract philosophical questions such as "What is justice? What is goodness?" It is initially painful, and one resents it, but eventually one recognizes that these abstractions are more real and more important. This is where the caricature of Platonism comes from — the idea that philosophy simply tells us to look upward and forget about the concrete world below.
But the allegory continues. If the freed prisoner decided to return to the cave, he would face the opposite problem: where it was once too bright, now it is too dark. His eyes are no longer accustomed to the darkness, and he stumbles around, unable to make out the shadows. The other prisoners would say he has been ruined by whoever dragged him out, and they would kill him if they could get their hands on him — a quiet allusion to the fate of Socrates.
I think Plato is saying exactly what you were suggesting. If you could combine the ability to think abstractly and attain wisdom at that level with the ability to "see in the dark" — to deal with particular situations and the nitty-gritty of politics — you would be truly wise. Plato goes on in The Republic to describe philosopher-rulers who would necessarily have to possess both kinds of wisdom. So I think we have a rough sense of what's going on in the Digression: Socrates is partly poking fun at someone like Theodorus, but also suggesting that a combination of abstract and particular knowledge would be the most desirable form of understanding.
Socrates — or Plato — is probably being quite sincere when, towards the end of the Digression, he criticizes people who take themselves to be very clever in getting away with injustice. But when, at 175C, someone asks him to examine justice and injustice themselves — what they are, how they differ from everything else and from each other — his head swims. Disconcerted by the unusual experience, he knows not what to do next; he can only stammer when he speaks. And this causes great entertainment to all men who have not been brought up like slaves.
He makes a similar point at 177B: when the unjust man is willing to stand his ground and give a logos — an argument — for the things he disparages, when he holds his position like a man instead of running away like a coward, an odd thing happens. In the end, the things he says do not satisfy even himself. We see this in Book One of the Republic, where Socrates argues with Thrasymachus, a sophist who claims that might makes right and that injustice is admirable if you can get away with it. Thrasymachus cannot ultimately defend that position, and he is defeated by Socrates.
Perhaps this means that the fact-value distinction — to return to that theme — is not as obvious as we tend to assume. It promotes a Thrasymachean, or perhaps Machiavellian, cynicism: forget judgments about right and wrong, just and unjust, and focus simply on what works — and often what works is what people consider unjust. But that may be a very narrow and, in fact, ignorant point of view. The punishment for living that way, Socrates says, is not something superficial like getting caught and thrown in jail, or going to hell. The punishment is the unjust life itself — it is, in itself, an unhappy life.
Turning to the idea that knowledge is simply subjective perception: when that view is applied to justice, a real objection emerges. Protagoras could say, "This is what I think justice is," and one could reply, "Well, the most just thing for me to do is to kill you." What could he say to that?
Audience: Couldn't he come back and say, "Well, killing me is just for you — it's not just for me. We're different, and as for me, I'm going to stick with the way I feel about things. I'm going to run away, or at least not let you kill me. But as for whether it's absolutely just — well, there's no such thing."
There are moral relativists today who are apparently content with that position. Whether they truly believe it is another question, because if you walk up and punch one of them in the stomach, the reaction will not be, "Oh, well, that was just for you but unjust for me." They will get angry and say, "That's not right." When push comes to shove, it seems, we are all moral absolutists.
After the digression, they return to the distinction between what is good and what is useful — a kind of fact-value distinction. At 177E, Socrates says: "It's surely this, the useful, that a government aims at when it legislates. A community always makes such laws as are most useful to it. Or do you think legislation may have some other object in view?" And Theodorus simply agrees.
Theodorus needs to do a little more thinking here. What else could the object of legislation be, other than what is in the interests of the city or the government? One could always ask cui bono — who is benefiting? The interest of the politician, or of a certain segment of the population, are always possibilities worth considering.
But isn't there also a possible higher goal — justice itself? Shouldn't we at least try to create laws that are just? If we question the absolute distinction between what works, which is treated as objective, and what is just, which is treated as merely relative, then perhaps it is valid to aim at laws that actually are just. Most of us want our laws to be just, and when we feel they are unjust, we resent them — rightly so.
Socrates then develops the argument about prediction and the future that we have touched on. There are all sorts of experts — the expert chef, the expert teacher of gymnastics, the expert doctor — who can predict future outcomes better than others. Even Protagoras himself can predict which speech will be more effective than another, precisely because he is an expert rhetorician. This is a strong objection to Protagoras's position.
However, Socrates does not consider himself finished. At 179C, he says: "Maybe so long as we keep within the limits of the immediate present experience of the individual, it is more difficult to convict Protagoras of nonsense." Perhaps we should set aside the question of the future and focus on the present moment, which is where Protagoras seems to have his strongest foothold. The present perception of a particular individual — how could that ever be wrong? Isn't that knowledge? And this brings us to nearly the last part of the discussion.
This passage is part of the refutation of the idea that knowledge is perception, but we first get an interesting description of the followers of Heraclitus. Some of you may have read Jacques Derrida, who was perhaps a bit less popular after his death than he was from the 1960s through the 1990s, but he was the creator of deconstruction. I think Socrates' description of the Heracliteans is a bit like the behavior of the deconstructionists.
"As for abiding by what is said, or sticking to a question, or quietly answering and asking questions in turn, there is less than nothing of that in their capacity. If you ask any of them a question, he will pull out some little enigmatic phrase from his quiver and shoot it off at you; if you try to make him give an account of what he said, you will only get hit by another full of strange turns of language." We still have people like this, whether they are Derrideans or not — clever masters of evasion.
This fits the picture of Heraclitus that we are getting in this dialogue: someone who says that everything is always moving around, that everything is relative, and who cannot be pinned down to any thesis. On the other hand, there are the followers of Parmenides. So we have a wonderful depiction here of the great battle being waged between the Heracliteans and the Parmenideans.
Let me offer a brief digression on Parmenides. If Heraclitus — at least as he is perhaps caricatured in this dialogue — is the philosopher who said "Everything is in flux," then Parmenides, the other of the two greatest pre-Socratic philosophers, is the one who says "Nothing is in flux; everything is a single, unchanging thing." Would Parmenides agree that knowledge is perception? Not at all. The truth is eternal and timeless, and being itself is timeless. Since perception shows us only the changing world, if you truly deny that there is any change, you must reject perception altogether.
Parmenides therefore says: trust your logic, trust your mind, and disregard what your senses tell you. What does logic tell you? Here is what seems to be the most solid of all statements: being is. What is, is — who can argue with that? And its complementary statement: non-being is not. There is no nothing; nothing does not exist.
Several interesting consequences follow from this. If being is, and non-being is merely a placeholder for something we cannot even fathom, then being must be one, because you could not divide being except by means of more being. Any differentiation requires that something not be something else — but that is already a form of non-being. Since non-being does not exist, there can be no differentiation whatsoever. Parmenides compares being to a single, well-rounded sphere.
Can there be change? Change occurs when something becomes what it was not before — when something that is not becomes something that is, and then perhaps becomes something that is not again. But there is no thing that is not; there is no non-being. Therefore there is no transition from non-being to being, there is no transition of any kind, and the testimony of the senses is an absolute illusion.
A famous follower of Parmenides, Zeno, is responsible for some wonderful paradoxes. One holds that I cannot cross to the other side of the room, because first I would have to get halfway there, then halfway again, then halfway again, and so on — an infinite series of finite distances that I could never complete. People still discuss this paradox today; some think calculus resolves it, though perhaps that is a little too simple. My favorite of Zeno's paradoxes is the arrow paradox, because it is so elegant. Take an arrow shooting through the air and consider it at a single instant: is it moving at that instant? No — there is no time within an instant in which it can move. At no instant is it moving, therefore it never moves.
That, then, is Parmenides. The dialogue offers a brief promise that Parmenideanism will be discussed further, but Socrates quickly says it is too deep for the present moment. If you wish to explore this further, there is a wonderful dialogue by Plato simply called the Parmenides, in which a young Socrates meets an elderly Parmenides who thoroughly defeats him in argument. If you want to see Socrates finally bested — at least in his youth — that is the dialogue to read.
We will focus exclusively on the Heracliteans, who are always squirming their way out of any attempt to come to grips with them. As Theodorus says at 180c, "What we must do is take their doctrine out of their hands and consider it for ourselves as we should a problem in geometry." Whether they like it or not, we are going to take their basic statement — everything flows, everything is in flux — and treat it as an axiom in mathematics, then see what follows from it.
The axiom is that everything is in motion. Socrates asks at 181c, "Are they referring to one form of motion only, or, as I think, to two?" We are taking motion in a broad sense to mean change. The first kind is motion in the narrow sense: change of place. The second kind is alteration — how things change in quality.
Consider a concrete example: we have been meeting for a few days, and my beard has grown. I am still here sitting at this table; I have not moved in any dramatic sense. Yet something about me has changed. Similarly, the room may have grown a little warmer over the course of this class. That seems to be a change of quality rather than a change of location.
Audience: Isn't the beard growing a change of place, since it's spatial?
In a sense, yes — and in modern physics, what does it mean to become warmer? It is, at bottom, just molecules moving around faster, which is motion in space. There is indeed a tendency in modern philosophy and science to reduce all changes of quality to changes in location. By common sense, however, and certainly by ancient common sense, these are two distinct kinds of change.
There is change of place, and there is change of poiotēs — hoiousness, or what-it-is-like-ness — a word Plato coins in this very dialogue. Cicero, imitating this coinage in Latin, invented the word qualitas, from which we get quality and qualitative. A change of color or a change of temperature would be examples. Aristotle, incidentally, would add a third kind of change: substantial transformation, as when an animal dies and its matter takes on an entirely new form. For the present argument, however, the crucial concept is alteration — change of quality.
What does universal flux imply about language? Consider 182c: "So all things move and flow," according to the Heracliteans. "They both move and alter. Now if they were only moving through space and not altering, we should presumably be able to say what the moving things flow." Socrates is trying to avoid saying what things are, avoiding the word being altogether. Consider a butterfly: even though it constantly changes position, it is still a butterfly. But if it is also altering in quality, then its butterfly-ness would no longer remain the same — it would no longer be a butterfly at all.
This raises the question of how one can speak about anything. Plato tells us that one follower of Heraclitus gave up on language entirely and simply pointed at events. The problem is that as soon as you make a statement about something, you are virtually pinning it down as a certain kind of thing, described by a noun or a name. Any such description implies a stable identity — precisely what universal flux denies.
At 183a, Socrates presses the point further: "If all things are in motion, every answer on whatever subject is equally correct — both it is thus and it is not thus, or if you like, becomes." This would mean that the statement knowledge is perception is just as correct as knowledge is not perception. If something is perception at one instant, it will not be perception in the next, because even perception-ness is a quality that is constantly shifting into something else. Universal flux therefore destroys language and conceptual thought altogether.
This brings us back to the question of whether we have refuted the claim that knowledge is perception. The argument began with that statement, which Socrates identified with what Protagoras said — and, more fundamentally, with what Heraclitus meant. If you follow Heraclitus, then any statement of the form A is B is no more true than A is not B. Applying this to the original claim, knowledge is perception is no more true than knowledge is not perception. It is a convoluted, indirect, and clever refutation: after several steps, the argument comes full circle and undercuts any attempt to make a stable statement about knowledge whatsoever.
Socrates could have stopped here and moved on, but he is not satisfied — and I am glad he is not, because the next argument is less open to suspicion of sophistry. It is more firmly grounded in phenomenology: an actual description of the experience of sense perception, which has been sorely lacking so far. Much has been said about perception in the abstract, but now we are asked to pay close attention to how perception actually works.
Socrates will ask us to examine our experience of seeing, hearing, and the other senses directly. From that examination, he will demonstrate that sense perception alone cannot possibly be sufficient to count as knowledge. I think you will find the argument convincing, and we will work through it tomorrow.