THEAETETUS: Very good.
SOCRATES: And do you mean by conceiving, the same which I mean?
THEAETETUS: What is that?
SOCRATES: I mean the conversation which the soul holds with herself in considering of anything. I speak of what I scarcely understand; but the soul when thinking appears to me to be just talking--asking questions of herself and answering them, affirming and denying. And when she has arrived at a decision, either gradually or by a sudden impulse, and has at last agreed, and does not doubt, this is called her opinion. I say, then, that to form an opinion is to speak, and opinion is a word spoken,--I mean, to oneself and in silence, not aloud or to another: What think you?
THEAETETUS: I agree.
SOCRATES: Then when any one thinks of one thing as another, he is saying to himself that one thing is another?
THEAETETUS: Yes.
SOCRATES: But do you ever remember saying to yourself that the noble is certainly base, or the unjust just; or, best of all--have you ever attempted to convince yourself that one thing is another? Nay, not even in sleep, did you ever venture to say to yourself that odd is even, or anything of the kind?
THEAETETUS: Never.
SOCRATES: And do you suppose that any other man, either in his senses or out of them, ever seriously tried to persuade himself that an ox is a horse, or that two are one?
THEAETETUS: Certainly not.
SOCRATES: But if thinking is talking to oneself, no one speaking and thinking of two objects, and apprehending them both in his soul, will say and think that the one is the other of them, and I must add, that even you, lover of dispute as you are, had better let the word 'other' alone (i.e. not insist that 'one' and 'other' are the same (Both words in Greek are called eteron: compare Parmen.; Euthyd.)). I mean to say, that no one thinks the noble to be base, or anything of the kind.
THEAETETUS: I will give up the word 'other,' Socrates; and I agree to what you say.
SOCRATES: If a man has both of them in his thoughts, he cannot think that the one of them is the other?
THEAETETUS: True.
SOCRATES: Neither, if he has one of them only in his mind and not the other, can he think that one is the other?
THEAETETUS: True; for we should have to suppose that he apprehends that which is not in his thoughts at all.
SOCRATES: Then no one who has either both or only one of the two objects in his mind can think that the one is the other. And therefore, he who maintains that false opinion is heterodoxy is talking nonsense; for neither in this, any more than in the previous way, can false opinion exist in us.
THEAETETUS: No.
SOCRATES: But if, Theaetetus, this is not admitted, we shall be driven into many absurdities.
THEAETETUS: What are they?
SOCRATES: I will not tell you until I have endeavoured to consider the matter from every point of view. For I should be ashamed of us if we were driven in our perplexity to admit the absurd consequences of which I speak. But if we find the solution, and get away from them, we may regard them only as the difficulties of others, and the ridicule will not attach to us. On the other hand, if we utterly fail, I suppose that we must be humble, and allow the argument to trample us under foot, as the sea-sick passenger is trampled upon by the sailor, and to do anything to us. Listen, then, while I tell you how I hope to find a way out of our difficulty.
THEAETETUS: Let me hear.
SOCRATES: I think that we were wrong in denying that a man could think what he knew to be what he did not know; and that there is a way in which such a deception is possible.
THEAETETUS: You mean to say, as I suspected at the time, that I may know Socrates, and at a distance see some one who is unknown to me, and whom I mistake for him--then the deception will occur?
SOCRATES: But has not that position been relinquished by us, because involving the absurdity that we should know and not know the things which we know?
THEAETETUS: True.
SOCRATES: Let us make the assertion in another form, which may or may not have a favourable issue; but as we are in a great strait, every argument should be turned over and tested. Tell me, then, whether I am right in saying that you may learn a thing which at one time you did not know?
Theaetetus · The Wunder Library — complete classics, free to read, with narration.