PLATO. Hoshang Khambatta

He points out that if he had asked what clay is, and Theaetetus had answered the clay of potters, and the clay of brick makers, and the clay of the stove makers, those responses would be absurd. Theaetetus hesitantly agrees with this conclusion by Socrates. Socrates then emphasizes his response, saying that the person would not understand anything when he does not know what that thing (in this case, clay) is. Therefore, listing all the users of clay does not help in understanding what clay is. Thus, it follows that a man who does not understand what knowledge is will not understand the knowledge of shoes either. Furthermore, a man who does not understand what knowledge is will not understand what cobbling, or indeed any other craft, is. Socrates further emphasizes that when the question at hand is what knowledge is, to reply by naming one of the crafts is absurd. Such an answer points out something about what the knowledge might encompass, but does not answer the question of what knowledge is. Socrates adds that the best way to answer a query about the nature of clay is to say that it is a mixture of earth with liquid and point out whose clay it is.

      Socrates persuades Theaetetus to try to come up with an answer to the question of what knowledge is. Socrates likens himself to a midwife. As a midwife delivers babies, he is helping Theaetetus deliver answers. After much persuasion, Theaetetus comes up with an answer. A man who knows something perceives what he knows which defines knowledge simply as perception. Socrates is pleased with this reply as a frank answer, and therefore suggests that they must continue to discuss it. Socrates then points out that the sophist Protagoras also believed this definition by repeating Protagoras’ famous quote. “Man is the measure of all things, of the things which are, that they are, and the things which are not, that they are not.” This saying means that things that appear to me are true for me and things that appear to you are true for you. Theaetetus agrees with this explanation. Socrates adds that Protagoras, who is now dead, cannot defend himself, but having been a wise man, he was unlikely to have talked nonsense. Therefore, the statement requires further discussion. Socrates starts by giving an example of blowing wind. One person will feel cold but another will not. Thus, the same blowing wind appears to have a different effect to each individual. He explains that appears means as perceived by each of us and perception should be unerring, as befits knowledge. However, in this case each person has perceived the same thing differently. Socrates suggests that perhaps Protagoras put his statement out as a riddle for the common folk, but revealed the meaning in his book entitled Truth, in which he claimed that nothing in itself is just one thing. For example, calling a thing large overlooks the fact that it will be small in comparison to something larger. Likewise, something that might be judged heavy may be light in comparison to a yet heavier thing. Nothing is only one of anything or one of any kind of thing. Therefore, it comes down to this: When a person says that things “are,” they are consequently in a process of coming to be as a result of change. Socrates adds that this theory shows that being and becoming are products of motion, while not being and passing away originate from a state of rest. He goes on to say that heat is fire, and heat is generated by movement such as friction. Movement and motion generate everything. For example resting degenerates the body, whereas, in contrast, constant motion strengthens the body. This same difference applies with the condition of the soul. Learning and studying are motions; therefore the soul gains knowledge and thrives. In the state of rest, when the soul is not learning anything, a person not only fails to acquire knowledge but also forgets what he has previously learned. Thus, one can conclude that motion is beneficial for both body and soul. Socrates adds that what is perceived and its’ perception are similar. He concludes that perhaps the words “to be” ought to be abolished because there is continuous motion. This constant flux means that nothing can be said to be, but rather that everything is “coming to be.” Socrates once again wants to consider whether knowledge and perception are the same or different. He asks, whether a man who has learned something can be capable of not knowing it when recollecting it. Theaetetus says that this cannot happen. Socrates points out that seeing is perceiving and that sight is perception. Therefore a man who has seen something has come to know what he has seen. However, there is also something called “memory” to consider. So once something has been seen, it can be recalled at any time. It can be recalled even with the eyes shut. This situation, then, is different from what was discussed previously. A man who sees something has acquired knowledge of what he sees. Therefore, sight perception and knowledge are the same thing. Once a man has acquired knowledge of the object seen, he can remember it with his eyes shut. To say that he does not see it is to say that he does not know it, so if he sees, he knows. Socrates says that what all this means is that a man who has come to know and remember something, knows it even though he does not see it. This knowing is impossible when knowledge and perception are taken to be the same thing. Hence, it turns out that knowledge is one thing and perception is another.

      Socrates now poses another riddle. Is it possible for a man to know something and not to know this thing which he knows? Theaetetus replies that such a contradiction is impossible. Socrates asks what justification is there for saying that: “seeing is knowing.” In this fashion, Socrates scores several debating points over Theaetetus, who equated perception with knowledge. Socrates argues that the mind makes use of a range of concepts that it could not have acquired by observation and that do not operate through the senses. Hence, there is a part of knowledge that has nothing to do with perception. Thus, knowledge is not perception.

      Socrates notes again that Protagoras is dead and can not defend his statement that “man is the measure of all things.” Instead, he will try to defend the statement and offers a long monologue to this end. He adds that instead of him tormenting the young Theaetetus, perhaps Theodorus should join him in the question-and-answer debate. Theodorus agrees to this proposal and he and Socrates further discuss Protagoras’ statement. Socrates starts by stating that, according to Protagoras, things are for every man what they appear to be to himself. Theodorus agrees with this supposition. Socrates then points out that this insight means that all men express judgments of mankind. Socrates continues pointing out that all men agree that in some matters they are wiser than others, but that in other matters other men are wiser than they. This conclusion is more so in emergencies and in difficult situations when people look to other men as well as to The Gods for help. This activity takes place because the men who are called upon to solve the difficulty are superior in one thing that is knowledge of the situation. This conclusion, then, equates to the notion that men believe in the existence of both wisdom and ignorance amongst themselves. They believe that wisdom is true thinking, and that ignorance leads to false judgment. Theodorus also agrees with this conclusion. Socrates then asks what should be made of Protagoras’ argument. Can it be said that on every occasion all men correctly judge what is true? Or do they sometimes judge truly and sometimes not? If the latter is true, then human judgment is both true and false. Would anyone from Protagoras’ school be prepared to say that no one ever thinks that his neighbor is ignorant or judges falsely? Theodorus agrees that such a statement is unlikely. Socrates proposes that Theodorus come to a decision in his own mind and express his own judgment about it. Socrates continues, saying to Theodorus: “as per Protagoras, your judgment is true for you, but what about others who may disagree?” It is inevitable that people have to accept that Theodorus’ judgment is always true? What about all the others who think the opposite? Socrates continues, stating that in such a situation, Theodorus would want everyone to accept his judgment as true, even though thousands may disagree with it. Socrates adds that Protagoras admits to a contrary opinion when he says that all men judge what is. Thus, by admitting to a contrary opinion, Protagoras has admitted to the falsity of his own opinion. In the end, even Protagoras would have to admit that no man is the measure of anything. Therefore, this so called truth of Protagoras is not true for anyone, including Protagoras himself. The conclusion is then that some men are wiser than their fellows and that some other men are more ignorant. Socrates once again takes up Theaetetus’ explanation that perception is knowledge and asks him how a man sees colors or hears sounds. One could answer with that of course seeing is done with eyes and hearing is done with ears. Socrates asks whether a more precise wording would be by the use of words which would explain that people see through their eyes and similarly hear through the ears rather than with the eyes and ears. Theaetetus answers that “through” would be a more precise word here. Socrates concurs, pointing out that otherwise it would seem that people have a number of perceptions inside of themselves and that there is not one single form through which all of them converge, call it soul, or whatever. Socrates argues that