A Passage of Some Elegance in the Theaetetus

Abstract

151 e SOCRATES: Perception, you say is knowledge? THEAETETUS: Yes. SOCR.: The account you give of the nature of knowledge is not, by any means, to be despised. It is the same that was given by Protagoras, though he stated it in a somewhat different way. He says, you will remember, that 'man is the measure of all things alike of the being of things that are and of the not-being of things that are not.' No doubt you have read that. THEAET.: Yes, often. SOCR.: He puts it in this sort of way, doesn't he? that any given thing 'is to me such as it appears to me, and is to you such as it appears to you,' you and I being men. THEAET.: Yes, that is how he puts it. SOCR.: Well, what a wise man says is not likely to be nonsense. So let us follow up his meaning. Sometimes, when the same wind is blowing, one of us feels chilly, the other does not; or one may feel slightly chilly, the other quite cold. THEAET.: Certainly. SOCR.: Well, in that case are we to say that the wind in itself is cold or not cold? Or shall we agree with Protagoras that it is cold to the one who feels chilly, and not to the other? THEAET.: That seems reasonable. SOCR.: And further that it so 'appears' to each of us? THEAET.: Yes. SOCR.: And 'appears' means that he 'perceives' it so? THEAET.: True. SOCR.: 'Appearing,' then, is the same thing as 'perceiving,' in the case of what is hot or anything or that kind. They are to each man such as he perceives them. THEAET.: So it seems. SOCR.: Perception, then, is always of something that is, and, as being knowledge, it is infallible.