Dialogues of Plato - MobileReference [986]
THEAETETUS: Yes.
SOCRATES: And when transmitting them he may be said to teach them, and when receiving to learn them, and when receiving to learn them, and when having them in possession in the aforesaid aviary he may be said to know them.
THEAETETUS: Exactly.
SOCRATES: Attend to what follows: must not the perfect arithmetician know all numbers, for he has the science of all numbers in his mind?
THEAETETUS: True.
SOCRATES: And he can reckon abstract numbers in his head, or things about him which are numerable?
THEAETETUS: Of course he can.
SOCRATES: And to reckon is simply to consider how much such and such a number amounts to?
THEAETETUS: Very true.
SOCRATES: And so he appears to be searching into something which he knows, as if he did not know it, for we have already admitted that he knows all numbers;--you have heard these perplexing questions raised?
THEAETETUS: I have.
SOCRATES: May we not pursue the image of the doves, and say that the chase after knowledge is of two kinds? one kind is prior to possession and for the sake of possession, and the other for the sake of taking and holding in the hands that which is possessed already. And thus, when a man has learned and known something long ago, he may resume and get hold of the knowledge which he has long possessed, but has not at hand in his mind.
THEAETETUS: True.
SOCRATES: That was my reason for asking how we ought to speak when an arithmetician sets about numbering, or a grammarian about reading? Shall we say, that although he knows, he comes back to himself to learn what he already knows?
THEAETETUS: It would be too absurd, Socrates.
SOCRATES: Shall we say then that he is going to read or number what he does not know, although we have admitted that he knows all letters and all numbers?
THEAETETUS: That, again, would be an absurdity.
SOCRATES: Then shall we say that about names we care nothing?--any one may twist and turn the words 'knowing' and 'learning' in any way which he likes, but since we have determined that the possession of knowledge is not the having or using it, we do assert that a man cannot not possess that which he possesses; and, therefore, in no case can a man not know that which he knows, but he may get a false opinion about it; for he may have the knowledge, not of this particular thing, but of some other;--when the various numbers and forms of knowledge are flying about in the aviary, and wishing to capture a certain sort of knowledge out of the general store, he takes the wrong one by mistake, that is to say, when he thought eleven to be twelve, he got hold of the ring-dove which he had in his mind, when he wanted the pigeon.
THEAETETUS: A very rational explanation.
SOCRATES: But when he catches the one which he wants, then he is not deceived, and has an opinion of what is, and thus false and true opinion may exist, and the difficulties which were previously raised disappear. I dare say that you agree with me, do you not?
THEAETETUS: Yes.
SOCRATES: And so we are rid of the difficulty of a man's not knowing what he knows, for we are not driven to the inference that he does not possess what he possesses, whether he be or be not deceived. And yet I fear that a greater difficulty is looking in at the window.
THEAETETUS: What is it?
SOCRATES: How can the exchange of one knowledge for another ever become false opinion?
THEAETETUS: What do you mean?
SOCRATES: In the first place, how can a man who has the knowledge of anything be ignorant of that which he knows, not by reason of ignorance, but by reason of his own knowledge? And, again, is it not an extreme absurdity that he should suppose another thing to be this, and this to be another thing;--that, having knowledge present with him in his mind, he should still know nothing and be ignorant of all things?--you might as well argue that ignorance may make a man know, and blindness make him see, as that knowledge can make him ignorant.
THEAETETUS: