Theaetetus

SOCRATES: And every one who is not born deaf or dumb is able sooner or later to manifest what he thinks of anything; and if so, all those who have a right opinion about anything will also have right explanation; nor will right opinion be anywhere found to exist apart from knowledge.

THEAETETUS: True.

SOCRATES: Let us not, therefore, hastily charge him who gave this account of knowledge with uttering an unmeaning word; for perhaps he only intended to say, that when a person was asked what was the nature of anything, he should be able to answer his questioner by giving the elements of the thing.

THEAETETUS: As for example, Socrates…?

SOCRATES: As, for example, when Hesiod says that a waggon is made up of a hundred planks. Now, neither you nor I could describe all of them individually; but if any one asked what is a waggon, we should be content to answer, that a waggon consists of wheels, axle, body, rims, yoke.

THEAETETUS: Certainly.

SOCRATES: And our opponent will probably laugh at us, just as he would if we professed to be grammarians and to give a grammatical account of the name of Theaetetus, and yet could only tell the syllables and not the letters of your name – that would be true opinion, and not knowledge; for knowledge, as has been already remarked, is not attained until, combined with true opinion, there is an enumeration of the elements out of which anything is composed.

THEAETETUS: Yes.

SOCRATES: In the same general way, we might also have true opinion about a waggon; but he who can describe its essence by an enumeration of the hundred planks, adds rational explanation to true opinion, and instead of opinion has art and knowledge of the nature of a waggon, in that he attains to the whole through the elements.

THEAETETUS: And do you not agree in that view, Socrates?

SOCRATES: If you do, my friend; but I want to know first, whether you admit the resolution of all things into their elements to be a rational explanation of them, and the consideration of them in syllables or larger combinations of them to be irrational – is this your view?

THEAETETUS: Precisely.

SOCRATES: Well, and do you conceive that a man has knowledge of any element who at one time affirms and at another time denies that element of something, or thinks that the same thing is composed of different elements at different times?

THEAETETUS: Assuredly not.

SOCRATES: And do you not remember that in your case and in that of others this often occurred in the process of learning to read?

THEAETETUS: You mean that I mistook the letters and misspelt the syllables?

SOCRATES: Yes.

THEAETETUS: To be sure; I perfectly remember, and I am very far from supposing that they who are in this condition have knowledge.

SOCRATES: When a person at the time of learning writes the name of Theaetetus, and thinks that he ought to write and does write Th and e; but, again, meaning to write the name of Theododorus, thinks that he ought to write and does write T and e – can we suppose that he knows the first syllables of your two names?

THEAETETUS: We have already admitted that such a one has not yet attained knowledge.

SOCRATES: And in like manner be may enumerate without knowing them the second and third and fourth syllables of your name?

THEAETETUS: He may.

SOCRATES: And in that case, when he knows the order of the letters and can write them out correctly, he has right opinion?

THEAETETUS: Clearly.

SOCRATES: But although we admit that he has right opinion, he will still be without knowledge?

THEAETETUS: Yes.

SOCRATES: And yet he will have explanation, as well as right opinion, for he knew the order of the letters when he wrote; and this we admit to be explanation.

THEAETETUS: True.

SOCRATES: Then, my friend, there is such a thing as right opinion united with definition or explanation, which does not as yet attain to the exactness of knowledge.

THEAETETUS: It would seem so.

SOCRATES: And what we fancied to be a perfect definition of knowledge is a dream only. But perhaps we had better not say so as yet, for were there not three explanations of knowledge, one of which must, as we said, be adopted by him who maintains knowledge to be true opinion combined with rational explanation? And very likely there may be found some one who will not prefer this but the third.

THEAETETUS: You are quite right; there is still one remaining. The first was the image or expression of the mind in speech; the second, which has just been mentioned, is a way of reaching the whole by an enumeration of the elements. But what is the third definition?

SOCRATES: There is, further, the popular notion of telling the mark or sign of difference which distinguishes the thing in question from all others.

THEAETETUS: Can you give me any example of such a definition?

SOCRATES: As, for example, in the case of the sun, I think that you would be contented with the statement that the sun is the brightest of the heavenly bodies which revolve about the earth.

THEAETETUS: Certainly.

SOCRATES: Understand why: – the reason is, as I was just now saying, that if you get at the difference and distinguishing characteristic of each thing, then, as many persons affirm, you will get at the definition or explanation of it; but while you lay hold only of the common and not of the characteristic notion, you will only have the definition of those things to which this common quality belongs.

THEAETETUS: I understand you, and your account of definition is in my judgment correct.

SOCRATES: But he, who having right opinion about anything, can find out the difference which distinguishes it from other things will know that of which before he had only an opinion.

THEAETETUS: Yes; that is what we are maintaining.

SOCRATES: Nevertheless, Theaetetus, on a nearer view, I find myself quite disappointed; the picture, which at a distance was not so bad, has now become altogether unintelligible.

THEAETETUS: What do you mean?

SOCRATES: I will endeavour to explain: I will suppose myself to have true opinion of you, and if to this I add your definition, then I have knowledge, but if not, opinion only.

THEAETETUS: Yes.

SOCRATES: The definition was assumed to be the interpretation of your difference.

THEAETETUS: True.

SOCRATES: But when I had only opinion, I had no conception of your distinguishing characteristics.

THEAETETUS: I suppose not.

SOCRATES: Then I must have conceived of some general or common nature which no more belonged to you than to another.

THEAETETUS: True.