The Complete Aristotle (eng.)

they were trying to compel his son, a youth under
the prescribed age, to perform one of the state duties because he
was tall, said ‘If you count tall boys men, you will next be voting
short men boys’. And Theodectes in his Law said, ‘You make citizens
of such mercenaries as Strabax and Charidemus, as a reward of their
merits; will you not make exiles of such citizens as those who have
done irreparable harm among the mercenaries?’
    17. Another line is the argument that if two results are the
same their antecedents are also the same. For instance, it was a
saying of Xenophanes that to assert that the gods had birth is as
impious as to say that they die; the consequence of both statements
is that there is a time when the gods do not exist. This line of
proof assumes generally that the result of any given thing is
always the same: e.g. ‘you are going to decide not about Isocrates,
but about the value of the whole profession of philosophy.’ Or, ‘to
give earth and water’ means slavery; or, ‘to share in the Common
Peace’ means obeying orders. We are to make either such assumptions
or their opposite, as suits us best.
    18. Another line of argument is based on the fact that men do
not always make the same choice on a later as on an earlier
occasion, but reverse their previous choice. E.g. the following
enthymeme: ‘When we were exiles, we fought in order to return; now
we have returned, it would be strange to choose exile in order not
to have to fight.’ one occasion, that is, they chose to be true to
their homes at the cost of fighting, and on the other to avoid
fighting at the cost of deserting their homes.
    19. Another line of argument is the assertion that some possible
motive for an event or state of things is the real one: e.g. that a
gift was given in order to cause pain by its withdrawal. This
notion underlies the lines:
God gives to many great prosperity,
Not of good God towards them, but to make
The ruin of them more conspicuous.
    Or take the passage from the Meleager of Antiphon:
To slay no boar, but to be witnesses
Of Meleager’s prowess unto Greece.
    Or the argument in the Ajax of Theodectes, that Diomede chose
out Odysseus not to do him honour, but in order that his companion
might be a lesser man than himself-such a motive for doing so is
quite possible.
    20. Another line of argument is common to forensic and
deliberative oratory, namely, to consider inducements and
deterrents, and the motives people have for doing or avoiding the
actions in question. These are the conditions which make us bound
to act if they are for us, and to refrain from action if they are
against us: that is, we are bound to act if the action is possible,
easy, and useful to ourselves or our friends or hurtful to our
enemies; this is true even if the action entails loss, provided the
loss is outweighed by the solid advantage. A speaker will urge
action by pointing to such conditions, and discourage it by
pointing to the opposite. These same arguments also form the
materials for accusation or defence-the deterrents being pointed
out by the defence, and the inducements by the prosecution. As for
the defence,… This topic forms the whole Art of Rhetoric both of
Pamphilus and of Callippus.
    21. Another line of argument refers to things which are supposed
to happen and yet seem incredible. We may argue that people could
not have believed them, if they had not been true or nearly true:
even that they are the more likely to be true because they are
incredible. For the things which men believe are either facts or
probabilities: if, therefore, a thing that is believed is
improbable and even incredible, it must be true, since it is
certainly not believed because it is at all probable or credible.
An example is what Androcles of the deme Pitthus said in his
well-known arraignment of the law. The audience tried to shout him
down when he observed that the laws required a law to set them
right. ‘Why’, he went on, ‘fish need salt, improbable and
incredible as this might seem for creatures reared in salt water;
and olive-cakes need oil, incredible as it is that what produces
oil should need it.’
    22. Another line of argument is to refute our opponent’s case by
noting any contrasts or contradictions of dates, acts, or words
that it anywhere displays; and this in any of the three following
connexions. (1) Referring to our opponent’s conduct, e.g. ‘He says
he is devoted to you, yet he conspired with the Thirty.’