240–241
Stranger
Str. When, in talking about appearance, we say that he deceives and that his art is an art of deception, shall we say that our mind is misled by his art to hold a false opinion, or what shall we say?
Theaetetus
Theaet. We shall say that. What else could we say?
Stranger
Str. But, again, false opinion will be that which thinks the opposite of reality, will it not?
Stranger
Str. You mean, then, that false opinion thinks things which are not?
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Theaetetus
Theaet. Necessarily.
Stranger
Str. Does it think that things which are not, are not, or that things which are not at all, in some sense are?
Theaetetus
Theaet. It must think that things which are not in some sense are—that is, if anyone is ever to think falsely at all, even in a slight degree.
Stranger
Str. And does it not also think that things which certainly are, are not at all?
Theaetetus
Theaet. Yes.
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Stranger
Str. And this too is falsehood?
Theaetetus
Theaet. Yes, it is.
Stranger
Str. And therefore a statement will likewise be considered false, if it declares that things which are, are not, or that things which are not, are.
Theaetetus
Theaet. In what other way could a statement be made false?
Stranger
Str. Virtually in no other way; but the sophist will not assent to this. Or how can any reasonable man assent to it, when the expressions we just agreed upon were previously agreed to be inexpressible, unspeakable, irrational, and inconceivable? Do we understand his meaning, Theaetetus?
