some one of the premisses is demolished, seeing that, given all the
premisses, the conclusion was bound to follow. Always, in dealing with
any proposition, be on the look-out for a line of argument both pro
and con: and on discovering it at once set about looking for the
solution of it: for in this way you will soon find that you have
trained yourself at the same time in both asking questions and
answering them. If we cannot find any one else to argue with, we
should argue with ourselves. Select, moreover, arguments relating to
the same thesis and range them side by side: for this produces a
plentiful supply of arguments for carrying a point by sheer force, and
in refutation also it is of great service, whenever one is well
stocked with arguments pro and con: for then you find yourself on your
guard against contrary statements to the one you wish to secure.
Moreover, as contributing to knowledge and to philosophic wisdom the
power of discerning and holding in one view the results of either of
two hypotheses is no mean instrument; for it then only remains to make
a right choice of one of them. For a task of this kind a certain
natural ability is required: in fact real natural ability just is
the power right to choose the true and shun the false. Men of
natural ability can do this; for by a right liking or disliking for
whatever is proposed to them they rightly select what is best.

  It is best to know by heart arguments upon those questions which are
of most frequent occurrence, and particularly in regard to those
propositions which are ultimate: for in discussing these answerers
frequently give up in despair. Moreover, get a good stock of
definitions: and have those of familiar and primary ideas at your
fingers' ends: for it is through these that reasonings are effected.
You should try, moreover, to master the heads under which other
arguments mostly tend to fall. For just as in 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.

                            THE END
.