Theaetetus

SOC. Because I have a reverential fear of examining in a flippant manner Melissus and the others who teach that the universe is one and motionless, and because I reverence still more one man, Parmenides. Parmenides seems to me to be, in Homer’s words,

one to be venerated

awful.

THEO. Yes, if that is your opinion, we ought to do so.

SOC. Consider, then, Theaetetus, this further point about what has been said. Now you answered that perception is knowledge, did you not?

THEAET. Yes.

SOC. If, then, anyone should ask you, By what does a man see white and black colors and by what does he hear high and low tones? you would, I fancy, say, By his eyes and ears.

THEAET. Yes, I should.

SOC. The easy use of words and phrases and the avoidance of strict precision is in general a sign of good breeding; indeed, the opposite is hardly worthy of a gentleman, but sometimes it is necessary, as now it is necessary to object to your answer, in so far as it is incorrect. Just consider; which answer is more correct, that our eyes are that by which we see or that through which we see, and our ears that by which or that through which we hear?

THEAET. I think, Socrates, we perceive through, rather than by them, in each case.

SOC. Yes, for it would be strange indeed, my boy, if there are many senses ensconced within us, as if we were so many wooden horses of Troy, and they do not all unite in one power, whether we should call it soul or something else, by which we perceive through these as instruments the objects of perception.

THEAET. I think what you suggest is more likely than the other way.

SOC. Now the reason why I am so precise about the matter is this: I want to know whether there is some one and the same power within ourselves by which we perceive black and white through the eyes, and again other qualities through the other organs, and whether you will be able, if asked, to refer all such activities to the body. But perhaps it is better that you make the statement in answer to a question than that I should take all the trouble for you. So tell me: do you not think that all the organs through which you perceive hot and hard and light and sweet are parts of the body? Or are they parts of something else?

THEAET. Of nothing else.

SOC. And will you also be ready to agree that it is impossible to perceive through one sense what you perceive through another; for instance, to perceive through sight what you perceive through hearing, or through hearing what you perceive through sight?

THEAET. Of course I shall.

SOC. Then if you have any thought about both of these together, you would not have perception about both together either through one organ or through the other.

THEAET. No.

SOC. Now in regard to sound and color, you have, in the first place, this thought about both of them, that they both exist?

THEAET. Certainly.

SOC. And that each is different from the other and the same as itself?

THEAET. Of course.

SOC. And that both together are two and each separately is one?

THEAET. Yes, that also.

SOC. And are you able also to observe whether they are like or unlike each other?

THEAET. May be.

SOC. Now through what organ do you think all this about them? For it is impossible to grasp that which is common to them both either through hearing or through sight. Here is further evidence for the point I am trying to make: if it were possible to investigate the question whether the two, sound and color, are bitter or not, you know that you will be able to tell by what faculty you will investigate it, and that is clearly neither hearing nor sight, but something else.

THEAET. Of course it is,—the faculty exerted through the tongue.

SOC. Very good. But through what organ is the faculty exerted which makes known to you that which is common to all things, as well as to these of which we are speaking—that which you call being and not-being, and the other attributes of things, about which we were asking just now? What organs will you assign for all these, through which that part of us which perceives gains perception of each and all of them?

THEAET. You mean being and not-being, and likeness and unlikeness, and identity and difference, and also unity and plurality as applied to them. And you are evidently asking also through what bodily organs we perceive by our soul the odd and the even and everything else that is in the same category.

SOC. Bravo, Theaetetus! you follow me exactly; that is just what I mean by my question.

THEAET. By Zeus, Socrates, I cannot answer, except that I think there is no special organ at all for these notions, as there are for those others; but it appears to me that the soul views by itself directly what all things have in common.

SOC. Why, you are beautiful, Theaetetus, and not, as Theodorus said, ugly; for he who speaks beautifully is beautiful and good. But besides being beautiful, you have done me a favor by relieving me from a long discussion, if you think that the soul views some things by itself directly and others through the bodily faculties; for that was my own opinion, and I wanted you to agree.

THEAET. Well, I do think so.

SOC. To which class, then, do you assign being; for this, more than anything else, belongs to all things?

THEAET. I assign them to the class of notions which the soul grasps by itself directly.

SOC. And also likeness and unlikeness and identity and difference?

THEAET. Yes.

SOC. And how about beautiful and ugly, and good and bad?

THEAET. I think that these also are among the things the essence of which the soul most certainly views in their relations to one another, reflecting within itself upon the past and present in relation to the future.

SOC. Stop there. Does it not perceive the hardness of the hard through touch, and likewise the softness of the soft?

THEAET. Yes.

SOC. But their essential nature and the fact that they exist, and their opposition to one another, and, in turn, the essential nature of this opposition, the soul itself tries to determine for us by reverting to them and comparing them with one another.

THEAET. Certainly.

SOC. Is it not true, then, that all sensations which reach the soul through the body, can be perceived by human beings, and also by animals, from the moment of birth; whereas reflections about these, with reference to their being and usefulness, are acquired, if at all, with difficulty and slowly, through many troubles, in other words, through education?

THEAET. Assuredly.

SOC. Is it, then, possible for one to attain truth who cannot even get as far as being?

THEAET. No.

SOC. And will a man ever have knowledge of anything the truth of which he fails to attain?

THEAET. How can he, Socrates?

SOC. Then knowledge is not in the sensations, but in the process of reasoning about them; for it is possible, apparently, to apprehend being and truth by reasoning, but not by sensation.

THEAET. So it seems.

SOC. Then will you call the two by the same name, when there are so great differences between them?

THEAET. No, that would certainly not be right.

SOC. What name will you give, then, to the one which includes seeing, hearing, smelling, being cold, and being hot?

THEAET. Perceiving. What other name can I give it?

SOC. Collectively you call it, then, perception?

THEAET. Of course.

SOC. By which, we say, we are quite unable to apprehend truth, since we cannot apprehend being, either.

THEAET. No; certainly not.

SOC. Nor knowledge either, then.

THEAET. No.

SOC. Then, Theaetetus, perception and knowledge could never be the same.

THEAET. Evidently not, Socrates; and indeed now at last it has been made perfectly clear that knowledge is something different from perception.

SOC. But surely we did not begin our conversation in order to find out what knowledge is not, but what it is. However, we have progressed so far, at least, as not to seek for knowledge in perception at all, but in some function of the soul, whatever name is given to it when it alone and by itself is engaged directly with realities.

THEAET. That, Socrates, is, I suppose, called having opinion.

SOC. You suppose rightly, my friend. Now begin again at the beginning. Wipe out all we said before, and see if you have any clearer vision, now that you have advanced to this point. Say once more what knowledge is.

THEAET. To say that all opinion is knowledge is impossible, Socrates, for there is also false opinion; but true opinion probably is knowledge. Let that be my answer. For if it is proved to be wrong as we proceed, I will try to give another, just as I have given this.

SOC. That is the right way, Theaetetus. It is better to speak up boldly than to hesitate about answering, as you did at first. For if we act in this way, one of two things will happen: either we shall find what we are after, or we shall be less inclined to think we know what we do not know at all; and surely even that would be a recompense not to be despised. Well, then, what do you say now? Assuming that there are two kinds of opinion, one true and the other false, do you define knowledge as the true opinion?

THEAET. Yes. That now seems to me to be correct.

SOC. Is it, then, still worth while, in regard to opinion, to take up again—?

THEAET. What point do you refer to?

SOC. Somehow I am troubled now and have often been troubled before, so that I have been much perplexed in my own reflections and in talking with others, because I cannot tell what this experience is which we human beings have, and how it comes about.

THEAET. What experience?

SOC. That anyone has false opinions. And so I am considering and am still in doubt whether we had better let it go or examine it by another method than the one we followed a while ago.

THEAET. Why not, Socrates, if there seems to be the least need of it? For just now, in talking about leisure, you and Theodorus said very truly that there is no hurry in discussions of this sort.

SOC. You are right in reminding me. For perhaps this is a good time to retrace our steps. For it is better to finish a little task well than a great deal imperfectly.

THEAET. Of course.

SOC. How, then, shall we set about it? What is it that we do say? Do we say that in every case of opinion there is a false opinion, and one of us has a false, and another a true opinion, because, as we believe, it is in the nature of things that this should be so?

THEAET. Yes, we do.

SOC. Then this, at any rate, is possible for us, is it not, regarding all things collectively and each thing separately, either to know or not to know them? For learning and forgetting, as intermediate stages, I leave out of account for the present, for just now they have no bearing upon our argument.

THEAET. Certainly, Socrates, nothing is left in any particular case except knowing or not knowing it.

SOC. Then he who forms opinion must form opinion either about what he knows or about what he does not know?

THEAET. Necessarily.

SOC. And it is surely impossible that one who knows a thing does not know it, or that one who does not know it knows it.

THEAET. Certainly.

SOC. Then does he who forms false opinions think that the things which he knows are not these things, but some others of the things he knows, and so, knowing both, is he ignorant of both?

THEAET. That is impossible, Socrates.

SOC. Well then, does he think that the things he does not know are other things which he does not know—which is as if a man who knows neither Theaetetus nor Socrates should conceive the idea that Socrates is Theaetetus or Theaetetus Socrates?

THEAET. That is impossible.

SOC. But surely a man does not think that the things he knows are the things he does not know, or again that the things he does not know are the things he knows.

THEAET. That would be a monstrous absurdity.

SOC. Then how could he still form false opinions? For inasmuch as all things are either known or unknown to us, it is impossible, I imagine, to form opinions outside of these alternatives, and within them it is clear that there is no place for fake opinion.

THEAET. Very true.

SOC. Had we, then, better look for what we are seeking, not by this method of knowing and not knowing, but by that of being and not being?

THEAET. What do you mean?

SOC. We may simply assert that he who on any subject holds opinions which are not, will certainly think falsely, no matter what the condition of his mind may be in other respects.

THEAET. That, again, is likely, Socrates.

SOC. Well then, what shall we say, Theaetetus, if anyone asks us, Is that which is assumed in common speech possible at all, and can any human being hold an opinion which is not, whether it be concerned with any of the things which are, or be entirely independent of them? We, I fancy, shall reply, Yes, when, in thinking, he thinks what is not true, shall we not?

THEAET. Yes.

SOC. And is the same sort of thing possible in any other field?

THEAET. What sort of thing?

SOC. For instance, that a man sees something, but sees nothing.

THEAET. How can he?

SOC. Yet surely if a man sees any one thing, he sees something that is. Or do you, perhaps, think one is among the things that are not?

THEAET. No, I do not.

SOC. Then he who sees any one thing, sees something that is.

THEAET. That is clear.

SOC. And therefore he who hears anything, hears some one thing and therefore hears what is.

THEAET. Yes.

SOC. And he who touches anything, touches some one thing, which is, since it is one?

THEAET. That also is true.

SOC. So, then, does not he who holds an opinion hold an opinion of some one thing?

THEAET. He must do so.

SOC. And does not he who holds an opinion of some one thing hold an opinion of something that is?

THEAET. I agree.

SOC. Then he who holds an opinion of what is not holds an opinion of nothing.

THEAET. Evidently.

SOC. Well then, he who holds an opinion of nothing, holds no opinion at all.

THEAET. That is plain, apparently.

SOC. Then it is impossible to hold an opinion of that which is not, either in relation to things that are, or independently of them.

THEAET. Evidently.

SOC. Then holding false opinion is something different from holding an opinion of that which is not?

THEAET. So it seems.

SOC. Then false opinion is not found to exist in us either by this method or by that which we followed a little while ago.

THEAET. No, it certainly is not.

SOC. But does not that which we call by that name arise after the following manner?

THEAET. After what manner?

SOC. We say that false opinion is a kind of interchanged opinion, when a person makes an exchange in his mind and says that one thing which exists is another thing which exists. For in this way he always holds an opinion of what exists, but of one thing instead of another; so he misses the object he was aiming at in his thought and might fairly be said to hold a false opinion.

THEAET. Now you seem to me to have said what is perfectly right. For when a man, in forming an opinion, puts ugly instead of beautiful, or beautiful instead of ugly, he does truly hold a false opinion.

SOC. Evidently, Theaetetus, you feel contempt of me, and not fear.

THEAET. Why in the world do you say that?

SOC. You think, I fancy, that I would not attack your truly false by asking whether it is possible for a thing to become slowly quick or heavily light, or any other opposite, by a process opposite to itself, in accordance, not with its own nature, but with that of its opposite. But I let this pass, that your courage may not fail. You are satisfied, you say, that false opinion is interchanged opinion?

THEAET. I am.

SOC. It is, then, in your opinion, possible for the mind to regard one thing as another and not as what it is.

THEAET. Yes, it is.

SOC. Now when one’s mind does this, does it not necessarily have a thought either of both things together or of one or the other of them?

THEAET. Yes, it must; either of both at the same time or in succession.

SOC. Excellent. And do you define thought as I do?

THEAET. How do you define it?

SOC. As the talk which the soul has with itself about any subjects which it considers. You must not suppose that I know this that I am declaring to you. But the soul, as the image presents itself to me, when it thinks, is merely conversing with itself, asking itself questions and answering, affirming and denying. When it has arrived at a decision, whether slowly or with a sudden bound, and is at last agreed, and is not in doubt, we call that its opinion; and so I define forming opinion as talking and opinion as talk which has been held, not with someone else, nor yet aloud, but in silence with oneself. How do you define it?

THEAET. In the same way.

SOC. Then whenever a man has an opinion that one thing is another, he says to himself, we believe, that the one thing is the other.

THEAET. Certainly.

SOC. Now call to mind whether you have ever said to yourself that the beautiful is most assuredly ugly, or the wrong right, or—and this is the sum of the whole matter—consider whether you have ever tried to persuade yourself that one thing is most assuredly another, or whether quite the contrary is the case, and you have never ventured, even in sleep, to say to yourself that the odd is, after all, certainly even, or anything of that sort.

THEAET. You are right.

SOC. Do you imagine that anyone else, sane or insane, ever ventured to say to himself seriously and try to persuade himself that the ox must necessarily be a horse, or two one?

THEAET. No, by Zeus, I do not.

SOC. Then if forming opinion is talking to oneself, no one who talks and forms opinion of two objects and apprehends them both with his soul, could say and have the opinion that one is the other. But you will also have to give up the expression one and other. This is what I mean, that nobody holds the opinion that the ugly is beautiful, or anything of that sort.

THEAET. Well, Socrates, I do give it up; and I agree with you in what you say.

SOC. You agree, therefore, that he who holds an opinion of both things cannot hold the opinion that one is the other.

THEAET. So it seems.

SOC. But surely he who holds an opinion of one only, and not of the other at all, will never hold the opinion that one is the other.

THEAET. You are right; for he would be forced to apprehend also that of which he holds no opinion.

SOC. Then neither he who holds opinion of both nor he who holds it of one can hold the opinion that a thing is something else. And so anyone who sets out to define false opinion as interchanged opinion would be talking nonsense. Then neither by this method nor by our previous methods is false opinion found to exist in us.

THEAET. Apparently not.

SOC. But yet, Theaetetus, if this is found not to exist, we shall be forced to admit many absurdities.

THEAET. What absurdities?

SOC. I will not tell you until I have tried to consider the matter in every way. For I should be ashamed of us, if, in our perplexity, we were forced to make such admissions as those to which I refer. But if we find the object of our quest, and are set free from perplexity, then, and not before, we will speak of others as involved in those absurdities, and we ourselves shall stand free from ridicule. But if we find no escape from our perplexity, we shall, I fancy, become low-spirited, like seasick people, and shall allow the argument to trample on us and do to us anything it pleases. Hear, then, by what means I still see a prospect of success for our quest.

THEAET. Do speak.

SOC. I shall deny that we were right when we agreed that it is impossible for a man to have opinion that the things he does not know are the things which he knows, and thus to be deceived. But there is a way in which it is possible.

THEAET. Do you mean what I myself suspected when we made the statement to which you refer, that sometimes I, though I know Socrates, saw at a distance someone whom I did not know, and thought it was Socrates whom I do know? In such a case false opinion does arise.

SOC. But did not we reject that, because it resulted in our knowing and not knowing the things which we know?

THEAET. Certainly we did.

SOC. Let us, then, not make that assumption, but another; perhaps it will turn out well for us, perhaps the opposite. But we are in such straits that we must turn every argument round and test it from all sides. Now see if this is sensible: Can a man who did not know a thing at one time learn it later?

THEAET. To be sure he can.

SOC. Again, then, can he learn one thing after another?

THEAET. Why not?

SOC. Please assume, then, for the sake of argument, that there is in our souls a block of wax, in one case larger, in another smaller, in one case the wax is purer, in another more impure and harder, in some cases softer, and in some of proper quality.

THEAET. I assume all that.

SOC. Let us, then, say that this is the gift of Memory, the mother of the Muses, and that whenever we wish to remember anything we see or hear or think of in our own minds, we hold this wax under the perceptions and thoughts and imprint them upon it, just as we make impressions from seal rings; and whatever is imprinted we remember and know as long as its image lasts, but whatever is rubbed out or cannot be imprinted we forget and do not know.

THEAET. Let us assume that.

SOC. Now take a man who knows the things which he sees and hears, and is considering some one of them; observe whether he may not gain a false opinion in the following manner.

THEAET. In what manner?

SOC. By thinking that the things which he knows are sometimes things which he knows and sometimes things which he does not know. For we were wrong before in agreeing that this is impossible.

THEAET. What do you say about it now?

SOC. We must begin our discussion of the matter by making the following distinctions: It is impossible for anyone to think that one thing which he knows and of which he has received a memorial imprint in his soul, but which he does not perceive, is another thing which he knows and of which also he has an imprint, and which he does not perceive. And, again, he cannot think that what he knows is that which he does not know and of which he has no seal; nor that what he does not know is another thing which he does not know; nor that what he does not know is what he knows; nor can he think that what he perceives is something else which he perceives; nor that what he perceives is something which he does not perceive; nor that what he does not perceive is something else which he does not perceive; nor that what he does not perceive is something which he perceives. And, again, it is still more impossible, if that can be, to think that a thing which he knows and perceives and of which he has an imprint which accords with the perception is another thing which he knows and perceives and of which he has an imprint which accords with the perception. And he cannot think that what he knows and perceives and of which he has a correct memorial imprint is another thing which he knows; nor that a thing which he knows and perceives and of which he has such an imprint is another thing which he perceives; nor again that a thing which he neither knows nor perceives is another thing which he neither knows nor perceives; nor that a thing which he neither knows nor perceives is another thing which he does not know; nor that a thing which he neither knows nor perceives is another thing which he does not perceive. In all these cases it is impossible beyond everything for false opinion to arise in the mind of anyone. The possibility that it may arise remains, if anywhere, in the following cases.

THEAET. What cases are they? I hope they may help me to understand better; for now I cannot follow you.

SOC. The cases in which he may think that things which he knows are some other things which he knows and perceives; or which he does not know, but perceives; or that things which he knows and perceives are other things which he knows and perceives.

THEAET. Now I am even more out of the running than before.

SOC. Then let me repeat it in a different way. I know Theodorus and remember within myself what sort of a person he is, and just so I know Theaetetus, but sometimes I see them, and sometimes I do not, sometimes I touch them, sometimes not, sometimes I hear them or perceive them through some other sense, and sometimes I have no perception of you at all, but I remember you none the less and know you in my own mind. Is it not so?

THEAET. Certainly.

SOC. This, then, is the first of the points which I wish to make clear. Note that one may perceive or not perceive that which one knows.

THEAET. That is true.

SOC. So, too, with that which he does not know—he may often not even perceive it, and often he may merely perceive it?

THEAET. That too is possible.