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Pages of theaetetus

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yourself, or any other follower of Protagoras, would contend that no
one deems another ignorant or mistaken in his opinion?
Theod. The thing is incredible, Socrates.
Soc. And yet that absurdity is necessarily involved in the thesis
which declares man to be the measure of all things.
Theod. How so?
Soc. Why, suppose that you determine in your own mind something to
be true, and declare your opinion to me; let us assume, as he
argues, that this is true to you. Now, if so, you must either say that
the rest of us are not the judges of this opinion or judgment of
yours, or that we judge you always to have a true opinion: But are
there not thousands upon thousands who, whenever you form a
judgment, take up arms against you and are of an opposite judgment and
opinion, deeming that you judge falsely?
Theod. Yes, indeed, Socrates, thousands and tens of thousands, as
Homer says, who give me a world of trouble.
Soc. Well, but are we to assert that what you think is true to you
and false to the ten thousand others?
Theod. No other inference seems to be possible.
Soc. And how about Protagoras himself? If neither he nor the
multitude thought, as indeed they do not think, that man is the
measure of all things, must it not follow that the truth of which
Protagoras wrote would be true to no one? But if you suppose that he
himself thought this, and that the multitude does not agree with
him, you must begin by allowing that in whatever proportion the many
are more than one, in that proportion his truth is more untrue than
Theod. That would follow if the truth is supposed to vary with
individual opinion.
Soc. And the best of the joke is, that he acknowledges the truth
of their opinion who believe his own opinion to be false; for he
admits that the opinions of all men are true.
Theod. Certainly.
Soc. And does he not allow that his own opinion is false, if he
admits that the opinion of those who think him false is true?
Theod. Of course.
Soc. Whereas the other side do not admit that they speak falsely?
Theod. They do not.
Soc. And he, as may be inferred from his writings, agrees that
this opinion is also true.
Theod. Clearly.
Soc. Then all mankind, beginning with Protagoras, will contend, or
rather, I should say that he will allow, when he concedes that his
adversary has a true opinion-Protagoras, I say, will himself allow
that neither a dog nor any ordinary man is the measure of anything
which he has not learned-am I not right?
Theod. Yes.
Soc. And the truth of Protagoras being doubted by all, will be
true neither to himself to any one else?
Theod. I think, Socrates, that we are running my old friend too
Soc. But do not know that we are going beyond the truth.
Doubtless, as he is older, he may be expected to be wiser than we are.
And if he could only just get his head out of the world below, he
would have overthrown both of us again and again, me for talking
nonsense and you for assenting to me, and have been off and
underground in a trice. But as he is not within call, we must make the
best use of our own faculties, such as they are, and speak out what
appears to us to be true. And one thing which no one will deny is,
that there are great differences in the understandings of men.
Theod. In that opinion I quite agree.
Soc. And is there not most likely to be firm ground in the
distinction which we were indicating on behalf of Protagoras, viz.,
that most things, and all immediate sensations, such as hot, dry,

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