The Complete Aristotle (eng.)

geometry it is
useful to be practised in the elements, and in arithmetic to have
the multiplication table up to ten at one’s fingers’ ends-and
indeed it makes a great difference in one’s knowledge of the
multiples of other numbers too-likewise also in arguments it is a
great advantage to be well up in regard to first principles, and to
have a thorough knowledge of premisses at the tip of one’s tongue.
For just as in a person with a trained memory, a memory of things
themselves is immediately caused by the mere mention of their loci,
so these habits too will make a man readier in reasoning, because
he has his premisses classified before his mind’s eye, each under
its number. It is better to commit to memory a premiss of general
application than an argument: for it is difficult to be even
moderately ready with a first principle, or hypothesis.
    Moreover, you should get into the habit of turning one argument
into several, and conceal your procedure as darkly as you can: this
kind of effect is best produced by keeping as far as possible away
from topics akin to the subject of the argument. This can be done
with arguments that are entirely universal, e.g. the statement that
‘there cannot be one knowledge of more than one thing’: for that is
the case with both relative terms and contraries and
co-ordinates.
    Records of discussions should be made in a universal form, even
though one has argued only some particular case: for this will
enable one to turn a single rule into several. A like rule applies
in Rhetoric as well to enthymemes. For yourself, however, you
should as far as possible avoid universalizing your reasonings. You
should, moreover, always examine arguments to see whether they rest
on principles of general application: for all particular arguments
really reason universally, as well, i.e. a particular demonstration
always contains a universal demonstration, because it is impossible
to reason at all without using universals.
    You should display your training in inductive reasoning against
a young man, in deductive against an expert. You should try,
moreover, to secure from those skilled in deduction their
premisses, from inductive reasoners their parallel cases; for this
is the thing in which they are respectively trained. In general,
too, from your exercises in argumentation you should try to carry
away either a syllogism on some subject or a refutation or a
proposition or an objection, or whether some one put his question
properly or improperly (whether it was yourself or some one else)
and the point which made it the one or the other. For this is what
gives one ability, and the whole object of training is to acquire
ability, especially in regard to propositions and objections. For
it is the skilled propounder and objector who is, speaking
generally, a dialectician. To formulate a proposition is to form a
number of things into one-for the conclusion to which the argument
leads must be taken generally, as a single thing-whereas to
formulate an objection is to make one thing into many; for the
objector either distinguishes or demolishes, partly granting,
partly denying the statements proposed.
    Do not argue with every one, nor practise upon the man in the
street: for there are some people with whom any argument is bound
to degenerate. For against any one who is ready to try all means in
order to seem not to be beaten, it is indeed fair to try all means
of bringing about one’s conclusion: but it is not good form.
Wherefore the best rule is, not lightly to engage with casual
acquaintances, or bad argument is sure to result. For you see how
in practising together people cannot refrain from contentious
argument.
    It is best also to have ready-made arguments relating to those
questions in which a very small stock will furnish us with
arguments serviceable on a very large number of occasions. These
are those that are universal, and those in regard to which it is
rather difficult to produce points for ourselves from matters of
everyday experience.

On Sophistical Refutations
    Translated by W. A. Pickard-Cambridge
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    div id="book1" class="book" title="Book I">
    1
    Let us now discuss sophistic refutations, i.e. what appear to be
refutations but are really fallacies instead. We will begin in the
natural order with the first.
    That some reasonings are genuine, while others seem to be so but
are not, is evident. This happens with arguments, as also
elsewhere, through a certain likeness between the genuine and