CHAPTER 25

That logic is necessary

When one of those who were present said, "Persuade me that logic
is necessary," he replied: Do you wish me to prove this to you? The
answer was, "Yes." Then I must use a demonstrative form of speech.
This was granted. How then will you know if I am cheating you by
argument? The man was silent. Do you see, said Epictetus, that you
yourself are admitting that logic is necessary, if without it you
cannot know so much as this, whether logic is necessary or not
necessary

CHAPTER 26

What is the property of error

Every error comprehends contradiction: for since he who errs does
not wish to err, but to he right, it is plain that he does not do what
he wishes. For what does the thief wish to do? That which is for his
own interest. If, then, the theft is not for his interest, he does not
do that which he wishes. But every rational: soul is by nature
offended at contradiction, and so long as it does not understand
this contradiction, it is not hindered from doing contradictory
things: but when it does understand the contradiction, it must of
necessity avoid the contradiction and avoid it as much as a man must
dissent from the false when he sees that a thing is false; but so long
as this falsehood does not appear to him, he assents to it as to
truth.
He, then, is strong in argument and has the faculty of exhorting and
confuting, who is able to show to each man the contradiction through
which he errs and clearly to prove how he does not do that which he
wishes and does that which he does not wish. For if any one shall show
this, a man will himself withdraw from that which he does; but so long
as you do not show this, do not be surprised if a man persists in
his practice; for having the appearance of doing right, he does what
he does. For this reason Socrates, also trusting to this power, used
to say, "I am used to call no other witness of what I say, but I am
always satisfied with him with whom I am discussing, and I ask him
to give his opinion and call him as a witness, and through he is
only one, he is sufficient in the place of all." For Socrates knew
by what the rational soul is moved, just like a pair of scales, and
that it must incline, whether it chooses or not. Show the rational
governing faculty a contradiction, and it will withdraw from it; but
if you do not show it, rather blame yourself than him who is not
persuaded.