The Complete Aristotle (eng.)

‘the greater the good, the greater the evil
that is its opposite’: for they allege that health, which is a less
good thing than vigour, has a greater evil as its opposite: for
disease is a greater evil than debility. In this case too,
therefore, we have to withdraw the point objected to; for when it
has been withdrawn, the man is more likely to admit the
proposition, e.g. that ‘the greater good has the greater evil as
its opposite, unless the one good involves the other as well’, as
vigour involves health. This should be done not only when he
formulates an objection, but also if, without so doing, he refuses
to admit the point because he foresees something of the kind: for
if the point objected to be withdrawn, he will be forced to admit
the proposition because he cannot foresee in the rest of it any
case where it does not hold true: if he refuse to admit it, then
when asked for an objection he certainly will be unable to render
one. Propositions that are partly false and partly true are of this
type: for in the case of these it is possible by withdrawing a part
to leave the rest true. If, however, you formulate the proposition
on the strength of many cases and he has no objection to bring, you
may claim that he shall admit it: for a premiss is valid in
dialectics which thus holds in several instances and to which no
objection is forthcoming.
    Whenever it is possible to reason to the same conclusion either
through or without a reduction per impossibile, if one is
demonstrating and not arguing dialectically it makes no difference
which method of reasoning be adopted, but in argument with another
reasoning per impossibile should be avoided. For where one has
reasoned without the reduction per impossibile, no dispute can
arise; if, on the other hand, one does reason to an impossible
conclusion, unless its falsehood is too plainly manifest, people
deny that it is impossible, so that the questioners do not get what
they want.
    One should put forward all propositions that hold true of
several cases, and to which either no objection whatever appears or
at least not any on the surface: for when people cannot see any
case in which it is not so, they admit it for true.
    The conclusion should not be put in the form of a question; if
it be, and the man shakes his head, it looks as if the reasoning
had failed. For often, even if it be not put as a question but
advanced as a consequence, people deny it, and then those who do
not see that it follows upon the previous admissions do not realize
that those who deny it have been refuted: when, then, the one man
merely asks it as a question without even saying that it so
follows, and the other denies it, it looks altogether as if the
reasoning had failed.
    Not every universal question can form a dialectical proposition
as ordinarily understood, e.g. ‘What is man?’ or ‘How many meanings
has “the good”?’ For a dialectical premiss must be of a form to
which it is possible to reply ‘Yes’ or ‘No’, whereas to the
aforesaid it is not possible. For this reason questions of this
kind are not dialectical unless the questioner himself draws
distinctions or divisions before expressing them, e.g. ‘Good means
this, or this, does it not?’ For questions of this sort are easily
answered by a Yes or a No. Hence one should endeavour to formulate
propositions of this kind in this form. It is at the same time also
perhaps fair to ask the other man how many meanings of ‘the good’
there are, whenever you have yourself distinguished and formulated
them, and he will not admit them at all.
    Any one who keeps on asking one thing for a long time is a bad
inquirer. For if he does so though the person questioned keeps on
answering the questions, clearly he asks a large number of
questions, or else asks the same question a large number of times:
in the one case he merely babbles, in the other he fails to reason:
for reasoning always consists of a small number of premisses. If,
on the other hand, he does it because the person questioned does
not answer the questions, he is at fault in not taking him to task
or breaking off the discussion.
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3
    There are certain hypotheses upon which it is at once difficult
to bring, and easy to stand up to, an argument. Such (e.g.) are
those things which stand first and those which stand last in the
order of nature. For the former require definition, while the
latter have to be arrived at through many