Complete Works

by Plato, Cooper, John M. , Hutchinson, D. S.

  Now I think we ought to begin by examining the other party, the fluent fellows we started to pursue. If they appear to us to be talking sense, we will help them to drag us over to their side, and try to escape the others. But if those who make their stand for the whole appear to be nearer the [b] truth, we will take refuge with them from the men who ‘move what should not be moved’. And if it appears that neither party has a reasonable theory, then we shall be very absurd if we think that insignificant people like ourselves can have anything to say, after we have rejected the views of men who lived so long ago and possessed all wisdom. Think now, Theodorus, is it of any use for us to go forward upon such a dangerous venture?

  THEODORUS: We can’t refuse to examine the doctrines of these two schools, Socrates; that couldn’t be allowed.

  [c] SOCRATES: Then we must examine them, if you feel so strongly about it. Now it seems to me that the proper starting point of our criticism is the nature of motion; what is this thing that they are talking about when they say that all things are in motion? I mean, for example, are they referring to one form of motion only, or, as I think, to two—but don’t let this be only what I think. You commit yourself as well, so that we may come to grief together, if need be. Tell me, do you call it ‘motion’ when a thing changes from one place to another or turns round in the same place?

  THEODORUS: I do, yes.

  SOCRATES: Here then is one form of motion. Then supposing a thing [d] remains in the same place, but grows old, or becomes black instead of white, or hard instead of soft, or undergoes any other alteration; isn’t it right to say that here we have motion in another form?

  THEODORUS: Unquestionably.

  SOCRATES: Then I now have two forms of motion, alteration and spatial movement.

  THEODORUS: Yes; and that’s quite correct.

  SOCRATES: Then now that we have made this distinction, let us have a talk with the people who allege that all things are in motion. Let us ask them, ‘Do you hold that everything is in motion in both ways, that is, that [e] it both moves through space and undergoes alteration? Or do you suggest that some things are in motion in both ways, and some only in one or the other?’

  THEODORUS: Heaven knows, I can’t answer that. I suppose they would say, in both ways.

  SOCRATES: Yes; otherwise, my friend, it will turn out that, in their view, things are both moving and standing still; and it will be no more correct to say that all things are in motion than to say that all things stand still.

  THEODORUS: That’s perfectly true.

  SOCRATES: Then since they must be in motion, and there is no such thing anywhere as absence of motion, it follows that all things are always in [182] every kind of motion.

  THEODORUS: Yes, that must be so.

  SOCRATES: Then I want you to consider this point in their theory. As we were saying, they hold that the genesis of things such as warmth and whiteness occurs when each of them is moving, together with a perception, in the space between the active and passive factors: the passive factor thereby becoming percipient, but not a perception, while the active factor becomes such or such, but not a quality—isn’t that so? But perhaps ‘quality’ seems a strange word to you; perhaps you don’t quite understand it as a general expression.27 So I will talk about particular cases. What I mean is that the active factor becomes not warmth or whiteness, but warm and [b] white; and so on. You will remember, perhaps, that we said in the earlier stages of the argument that there is nothing which in itself is just one thing; and that this applies also to the active and passive factors. It is by the association of the two with one another that they generate perceptions and the things perceived; and in so doing, the active factor becomes such and such, while the passive factor becomes percipient.

  THEODORUS: Yes, I remember that, of course.

  SOCRATES: Then we need not concern ourselves about other points in [c] their doctrine, whether they mean what we say or something else. We must keep our eyes simply upon the object of our discussion. We must ask them this question: ‘According to you, all things move and flow; isn’t that so?’

  THEODORUS: Yes.

  SOCRATES: And they have both the motions that we distinguished, that is to say, they both move and alter?

  THEODORUS: That must be so, if they are to be wholly and completely in motion.

  SOCRATES: Now if they were only moving through space and not altering, we should presumably be able to say what the moving things flow? Or how do we express it?

  THEODORUS: That’s all right.

  [d] SOCRATES: But since not even this abides, that what flows flows white, but rather it is in process of change, so that there is flux of this very thing also, the whiteness, and it is passing over into another color, lest it be convicted of standing still in this respect—since that is so, is it possible to give any name to a color which will properly apply to it?

  THEODORUS: I don’t see how one could, Socrates; nor yet surely to anything else of that kind, if, being in flux, it is always quietly slipping away as you speak?

  SOCRATES: And what about any particular kind of perception; for example, [e] seeing or hearing? Does it ever abide, and remain seeing or hearing?

  THEODORUS: It ought not to, certainly, if all things are in motion.

  SOCRATES: Then we may not call anything seeing rather than not-seeing; nor indeed may we call it any other perception rather than not—if it be admitted that all things are in motion in every way?

  THEODORUS: No, we may not.

  SOCRATES: Yet Theaetetus and I said that knowledge was perception?

  THEODORUS: You did.

  SOCRATES: And so our answer to the question, ‘What is knowledge?’ gave something which is no more knowledge than not.

  [183] THEODORUS: It seems as if it did.

  SOCRATES: A fine way this turns out to be of making our answer right. We were most anxious to prove that all things are in motion, in order to make that answer come out correct; but what has really emerged is that, 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’, as we don’t want to use any expressions which will bring our friends to a standstill.

  THEODORUS: You are quite right.

  [b] SOCRATES: Well, yes, Theodorus, except that I said ‘thus’ and ‘not thus’. One must not use even the word ‘thus’; for this ‘thus’ would no longer be in motion; nor yet ‘not thus’ for here again there is no motion. The exponents of this theory need to establish some other language; as it is, they have no words that are consistent with their hypothesis—unless it would perhaps suit them best to use ‘not at all thus’ in a quite indefinite sense.

  THEODORUS: That would at least be an idiom most appropriate to them.

  [c] SOCRATES: Then we are set free from your friend, Theodorus. We do not yet concede to him that every man is the measure of all things, if he be not a man of understanding. And we are not going to grant that knowledge is perception, not at any rate on the line of inquiry which supposes that all things are in motion; we are not going to grant it unless Theaetetus here has some other way of stating it.

  THEODORUS: That’s very good hearing, Socrates, for when these matters were concluded I was to be set free from my task of answering you, according to our agreement, which specified the end of the discussion of Protagoras’ theory.

  THEAETETUS: Oh, no, indeed, Theodorus! Not till you and Socrates have [d] done what you proposed just now, and dealt with the other side, the people who say that the Universe stands still.

  THEODORUS: What’s this, Theaetetus? You at your age teaching your elders to be unjust and break their agreements? What you have got to do is to prepare to render account to Socrates yourself for the rest of the discussion.

  THEAETETUS: All right, if he likes. But I would rather have listened to a discussion of these views.

  THEODORUS: Well, challenging Socrates to an argument is like inviting ‘cavalry into the plain’. So ask your question
s and you shall hear.

  SOCRATES: But I don’t think, Theodorus, that I am going to be persuaded by Theaetetus to do what he demands. [e]

  THEODORUS: But what is it makes you unwilling?

  SOCRATES: Shame. I am afraid our criticism might be a very cheap affair. And if I feel like this before the many who have made the universe one and unmoved, Melissus and the rest of them, I feel it still more in the face of the One—Parmenides. Parmenides seems to me, in the words of Homer, to be ‘reverend’ and ‘awful’.28 I met him when I was very young and he was a very old man; and he seemed to me to have a wholly noble depth.29 [184] So I am afraid we might not understand even what he says; still less should we attain to his real thought. Above all, I am afraid that the very object of our discussion, the nature of knowledge, might be left unexamined amid the crowd of theories that will rush in upon us if we admit them; especially as the theory we have now brought up is one which involves unmanageably vast issues. To treat it as a sideshow would be insult and injury; while if it is adequately discussed, it is likely to spread out until it completely eclipses the problems of knowledge. We must not do either. What we must do is to make use of our midwife’s art to deliver Theaetetus [b] of the thoughts which he has conceived about the nature of knowledge.*

  THEODORUS: Well, if that is what you think proper, it must be done.

  SOCRATES: Now, Theaetetus, I want you to think about one point in what has been said. Your answer was that knowledge is perception, wasn’t it?

  THEAETETUS: Yes.

  SOCRATES: Now supposing you were asked: ‘With what does a man see white and black things, and with what does he hear high and low notes?’ You would reply, I imagine, ‘With his eyes and ears.’

  THEAETETUS: I should, yes.

  [c] SOCRATES: Now as a rule it is no sign of ill-breeding to be easy in the use of language and take no particular care in one’s choice of words; it is rather the opposite that gives a man away. But such exactness is sometimes necessary; and it is necessary here, for example, to fasten upon something in your answer that is not correct. Think now. Is it more correct to say that the eyes are that with which we see, or that through which we see? Do we hear with the ears or through the ears?

  THEAETETUS: Well, I should think, Socrates, that it is ‘through which’ we perceive in each case, rather than ‘with which.’

  [d] SOCRATES: Yes, my son. It would be a very strange thing, I must say, if there were a number of perceptions sitting inside us as if we were Wooden Horses, and there were not some single form, soul or whatever one ought to call it, to which all these converge—something with which, through those things,30 as if they were instruments, we perceive all that is perceptible.

  THEAETETUS: That sounds to me better than the other way of putting it.

  SOCRATES: Now the reason why I am being so precise with you is this. I want to know if it is with one and the same part of ourselves that we [e] reach, through our eyes to white and black things, and through the other means to yet further things; and whether, if asked, you will be able to refer all these to the body. But perhaps it would be better if you stated the answers yourself, rather than that I should busy myself on your behalf. Tell me: the instruments through which you perceive hot, hard, light, sweet things—do you consider that they all belong to the body? Or can they be referred elsewhere?

  THEAETETUS: No, they all belong to the body.

  SOCRATES: And are you also willing to admit that what you perceive [185] through one power, you can’t perceive through another? For instance, what you perceive through hearing, you couldn’t perceive through sight, and similarly what you perceive through sight you couldn’t perceive through hearing?

  THEAETETUS: I could hardly refuse to grant that.

  SOCRATES: Then suppose you think something about both; you can’t possibly be having a perception about both, either through one of these instruments or through the other?

  THEAETETUS: No.

  SOCRATES: Now take a sound and a color. First of all, don’t you think this same thing about both of them, namely, that they both are?

  THEAETETUS: I do.

  SOCRATES: Also that each of them is different from the other and the same as itself?

  [b] THEAETETUS: Of course.

  SOCRATES: And that both together are two, and each of them is one?

  THEAETETUS: Yes, I think that too.

  SOCRATES: Are you also able to consider whether they are like or unlike each other?

  THEAETETUS: Yes, I may be.

  SOCRATES: Now what is it through which you think all these things about them? It is not possible, you see, to grasp what is common to both either through sight or through hearing. Let us consider another thing which will show the truth of what we are saying. Suppose it were possible to inquire whether both are salty or not. You can tell me, of course, with [c] what you would examine them. It would clearly be neither sight nor hearing, but something else.

  THEAETETUS: Yes, of course; the power which functions through the tongue.

  SOCRATES: Good. Now through what does that power function which reveals to you what is common in the case both of all things and of these two—I mean that which you express by the words ‘is’ and ‘is not’ and the other terms used in our questions about them just now? What kind of instruments will you assign for all these? Through what does that which is percipient in us perceive all of them?

  THEAETETUS: You mean being and not-being, likeness and unlikeness, same and different; also one, and any other number applied to them. And [d] obviously too your question is about odd and even, and all that is involved with these attributes; and you want to know through what bodily instruments we perceive all these with the soul.

  SOCRATES: You follow me exceedingly well, Theaetetus. These are just the things I am asking about.

  THEAETETUS: But I couldn’t possibly say. All I can tell you is that it doesn’t seem to me that for these things there is any special instrument at all, as there is for the others. It seems to me that in investigating the common [e] features of everything the soul functions through itself.

  SOCRATES: Yes, Theaetetus, you would say that, because you are handsome and not ugly as Theodorus would have it.31 For handsome is as handsome says. And besides being handsome, you have done me a good turn; you have saved me a vast amount of talk if it seems to you that, while the soul considers some things through the bodily powers, there are others which it considers alone and through itself. This was what I thought myself, but I wanted you to think it too.

  THEAETETUS: Well, it does seem to me to be so. [186]

  SOCRATES: Now in which class do you put being? For that, above all, is something that accompanies everything.

  THEAETETUS: I should put it among the things which the soul itself reaches out after by itself.

  SOCRATES: Also like and unlike, same and different?

  THEAETETUS: Yes.

  SOCRATES: What about beautiful and ugly, good and bad?

  THEAETETUS: Yes, these too; in these, above all, I think the soul examines [b] their being in comparison with one another. Here it seems to be making a calculation within itself of past and present in relation to future.

  SOCRATES: Not so fast, now. Wouldn’t you say that it is through touch that the soul perceives the hardness of what is hard, and similarly the softness of what is soft?

  THEAETETUS: Yes.

  SOCRATES: But as regards their being—the fact that they are—their opposition to one another, and the being, again, of this opposition, the matter is different. Here the soul itself attempts to reach a decision for us by rising to compare them with one another.

  THEAETETUS: Yes, undoubtedly.

  [c] SOCRATES: And thus there are some things which all creatures, men and animals alike, are naturally able to perceive as soon as they are born; I mean, the experiences which reach the soul through the body. But calculations regarding their being and their advantageousness come, when they do, only as the result of a long and arduous development, involving
a good deal of trouble and education.

  THEAETETUS: Yes, that certainly is so.

  SOCRATES: Now is it possible for someone who does not even get at being to get at truth?

  THEAETETUS: No; it’s impossible.

  SOCRATES: And if a man fails to get at the truth of a thing, will he ever be a person who knows that thing?

  [d] THEAETETUS: I don’t see how, Socrates.

  SOCRATES: Then knowledge is to be found not in the experiences but in the process of reasoning about them; it is here, seemingly, not in the experiences, that it is possible to grasp being and truth.

  THEAETETUS: So it appears.

  SOCRATES: Then in the face of such differences, would you call both by the same name?

  THEAETETUS: One would certainly have no right to.

  SOCRATES: Now what name do you give to the former—seeing, hearing, smelling, feeling cold or warm?

  [e] THEAETETUS: I call that perceiving—what else could I call it?

  SOCRATES: So the whole lot taken together you call perception?

  THEAETETUS: Necessarily.

  SOCRATES: Which, we say, has no share in the grasping of truth, since it has none in the grasping of being.

  THEAETETUS: No, it has none.

  SOCRATES: So it has no share in knowledge either.

  THEAETETUS: No.

  SOCRATES: Then, Theaetetus, perception and knowledge could never be the same thing.

  THEAETETUS: No, apparently not, Socrates; we have now got the clearest possible proof that knowledge is something different from perception.

  SOCRATES: But our object in beginning this discussion was not to find [187] out what knowledge is not, but to find out what it is. However, we have made a little progress. We shall not now look for knowledge in sense-perception at all, but in whatever we call that activity of the soul when it is busy by itself about the things which are.