Theaetetus (209)

SOC. I will tell you if I can. Assume that I have right opinion about you; if I add the explanation or definition of you, then I have knowledge of you, otherwise I have merely opinion.

THEAET. Yes.

SOC. But explanation was, we agreed, the interpretation of your difference.

THEAET. It was.

SOC. Then so long as I had merely opinion, I did not grasp in my thought any of the points in which you differ from others?

THEAET. Apparently not.

SOC. Therefore I was thinking of some one of the common traits which you possess no more than other men.

THEAET. You must have been.

SOC. For heaven’s sake! How in the world could I in that case have any opinion about you more than about anyone else? Suppose that I thought That is Theaetetus which is a man and has nose and eyes and mouth and so forth, mentioning all the parts. Can this thought make me think of Theaetetus any more than of Theodorus or of the meanest of the Mysians, [*] as the saying is?

THEAET. Of course not.

SOC. But if I think not only of a man with nose and eyes, but of one with snub nose and protruding eyes, shall I then have an opinion of you any more than of myself and all others like me?

THEAET. Not at all.

SOC. No; I fancy Theaetetus will not be the object of opinion in me until this snubnosedness of yours has stamped and deposited in my mind a memorial different from those of the other examples of snubnosedness that I have seen, and the other traits that make up your personality have done the like. Then that memorial, if I meet you again tomorrow, will awaken my memory and make me have right opinion about you.

THEAET. Very true.

SOC. Then right opinion also would have to do with differences in any given instance?

THEAET. At any rate, it seems so.

SOC. Then what becomes of the addition of reason or explanation to right opinion? For if it is defined as the addition of an opinion of the way in which a given thing differs from the rest, it is an utterly absurd injunction.

THEAET. How so?

SOC. When we have a right opinion of the way in which certain things differ from other things, we are told to acquire a right opinion of the way in which those same things differ from other things! On this plan the twirling of a scytale [*] or a pestle or anything of the sort would be as nothing compared with this injunction. It might more justly be called a blind man’s giving directions; for to command us to acquire that which we already have, in order to learn that of which we already have opinion, is very like a man whose sight is mightily darkened.

THEAET. Tell me now, what did you intend to say when you asked the question a while ago?