philosopher does not care. Nay, he may possibly be even anxious to
secure axioms as familiar and as near to the question in hand as
possible: for these are the bases on which scientific reasonings are
built up.
The sources from which one's commonplace arguments should be drawn
have already been described:' we have now to discuss the arrangement
and formation of questions and first to distinguish the premisses,
other than the necessary premisses, which have to be adopted. By
necessary premisses are meant those through which the actual reasoning
is constructed. Those which are secured other than these are of four
kinds; they serve either inductively to secure the universal premiss
being granted, or to lend weight to the argument, or to conceal the
conclusion, or to render the argument more clear. Beside these there
is no other premiss which need be secured: these are the ones
whereby you should try to multiply and formulate your questions. Those
which are used to conceal the conclusion serve a controversial purpose
only; but inasmuch as an undertaking of this sort is always
conducted against another person, we are obliged to employ them as
well.
The necessary premisses through which the reasoning is effected,
ought not to be propounded directly in so many words. Rather one
should soar as far aloof from them as possible. Thus if one desires to
secure an admission that the knowledge of contraries is one, one
should ask him to admit it not of contraries, but of opposites: for,
if he grants this, one will then argue that the knowledge of
contraries is also the same, seeing that contraries are opposites;
if he does not, one should secure the admission by induction, by
formulating a proposition to that effect in the case of some
particular pair of contraries. For one must secure the necessary
premisses either by reasoning or by induction, or else partly by one
and partly by the other, although any propositions which are too
obvious to be denied may be formulated in so many words. This is
because the coming conclusion is less easily discerned at the
greater distance and in the process of induction, while at the same
time, even if one cannot reach the required premisses in this way,
it is still open to one to formulate them in so many words. The
premisses, other than these, that were mentioned above, must be
secured with a view to the latter. The way to employ them respectively
is as follows: Induction should proceed from individual cases to the
universal and from the known to the unknown; and the objects of
perception are better known, to most people if not invariably.
Concealment of one's plan is obtained by securing through
prosyllogisms the premisses through which the proof of the original
proposition is going to be constructed-and as many of them as
possible. This is likely to be effected by making syllogisms to
prove not only the necessary premisses but also some of those which
are required to establish them. Moreover, do not state the conclusions
of these premisses but draw them later one after another; for this
is likely to keep the answerer at the greatest possible distance
from the original proposition. Speaking generally, a man who desires
to get information by a concealed method should so put his questions
that when he has put his whole argument and has stated the conclusion,
people still ask 'Well, but why is that?' This result will be
secured best of all by the method above described: for if one states
only the final conclusion, it is unclear how it comes about; for the
answerer does not foresee on what grounds it is based, because the
previous syllogisms have not been made articulate to him: while the
final syllogism, showing the conclusion, is likely to be kept least
articulate if we lay down not the secured propositions on which it
is based, but only the grounds on which we reason to them.
It is a useful rule, too, not to secure the admissions claimed as
the bases of the syllogisms in their proper order, but alternately
those that conduce to one conclusion and those that conduce to
another; for, if those which go together are set side by side, the
conclusion that will result from them is more obvious in advance.
One should also, wherever possible, secure the universal premiss
by a definition relating not to the precise terms themselves but to
their co-ordinates; for people deceive themselves, whenever the
definition is taken in regard to a co-ordinate, into thinking that
they are not making the admission universally. An instance would be,
supposing one had to secure the admission that the angry man desires
vengeance on account of an apparent slight, and were to secure this,
that 'anger' is a desire for vengeance on account of an apparent
slight: for, clearly, if this were secured, we should have universally
what we intend. If, on the other hand, people formulate propositions
relating to the actual terms themselves, they often find that the
answerer refuses to grant them because on the actual term itself he is
readier with his objection, e.g. that the 'angry man' does not
desire vengeance, because we become angry with our parents, but we
do not desire vengeance on them. Very likely the objection is not
valid; for upon some people it is vengeance enough to cause them
pain and make them sorry; but still it gives a certain plausibility
and air of reasonableness to the denial of the proposition. In the
case, however, of the definition of 'anger' it is not so easy to
find an objection.
Moreover, formulate your proposition as though you did so not for
its own sake, but in order to get at something else: for people are
shy of granting what an opponent's case really requires. Speaking
generally, a questioner should leave it as far as possible doubtful
whether he wishes to secure an admission of his proposition or of
its opposite: for if it be uncertain what their opponent's argument
requires, people are more ready to say what they themselves think.
Moreover, try to secure admissions by means of likeness: for such
admissions are plausible, and the universal involved is less patent;
e.g. make the other person admit that as knowledge and ignorance of
contraries is the same, so too perception of contraries is the same;
or vice versa, that since the perception is the same, so is the
knowledge also. This argument resembles induction, but is not the same
thing; for in induction it is the universal whose admission is secured
from the particulars, whereas in arguments from likeness, what is
secured is not the universal under which all the like cases fall.
It is a good rule also, occasionally to bring an objection against
oneself: for answerers are put off their guard against those who
appear to be arguing impartially. It is useful too, to add that 'So
and so is generally held or commonly said'; for people are shy of
upsetting the received opinion unless they have some positive
objection to urge: and at the same time they are cautious about
upsetting such things because they themselves too find them useful.
Moreover, do not be insistent, even though you really require the
point: for insistence always arouses the more opposition. Further,
formulate your premiss as though it were a mere illustration: for
people admit the more readily a proposition made to serve some other
purpose, and not required on its own account. Moreover, do not
formulate the very proposition you need to secure, but rather
something from which that necessarily follows: for people are more
willing to admit the latter, because it is not so clear from this what
the result will be, and if the one has been secured, the other has
been secured also. Again, one should put last the point which one most
wishes to have conceded; for people are specially inclined to deny the
first questions put to them, because most people in asking questions
put first the points which they are most eager to secure. On the other
hand, in dealing with some people propositions of this sort should
be put forward first: for ill-tempered men admit most readily what
comes first, unless the conclusion that will result actually stares
them in the face, while at the close of an argument they show their
ill-temper. Likewise also with those who consider themselves smart
at answering: for when they have admitted most of what you want they
finally talk clap-trap to the effect that the conclusion does not
follow from their admissions: yet they say 'Yes' readily, confident in
their own character, and imagining that they cannot suffer any
reverse. Moreover, it is well to expand the argument and insert things
that it does not require at all, as do those who draw false
geometrical figures: for in the multitude of details the whereabouts
of the fallacy is obscured. For this reason also a questioner
sometimes evades observation as he adds in a corner what, if he
formulated it by itself, would not be granted.
For concealment, then, the rules which should be followed are the
above. Ornament is attained by induction and distinction of things
closely akin. What sort of process induction is obvious: as for
distinction, an instance of the kind of thing meant is the distinction
of one form of knowledge as better than another by being either more
accurate, or concerned with better objects; or the distinction of
sciences into speculative, practical, and productive. For everything
of this kind lends additional ornament to the argument, though there
is no necessity to say them, so far as the conclusion goes.
For clearness, examples and comparisons should be adduced, and let
the illustrations be relevant and drawn from things that we know, as
in Homer and not as in Choerilus; for then the proposition is likely
to become clearer.
2
In dialectics, syllogism should be employed in reasoning against
dialecticians rather than against the crowd: induction, on the other
hand, is most useful against the crowd. This point has been treated
previously as well.' In induction, it is possible in some cases to ask
the question in its universal form, but in others this is not easy,
because there is no established general term that covers all the
resemblances: in this case, when people need to secure the
universal, they use the phrase 'in all cases of this sort'. But it
is one of the very hardest things to distinguish which of the things
adduced are 'of this sort', and which are not: and in this connexion
people often throw dust in each others' eyes in their discussion,
the one party asserting the likeness of things that are not alike, and
the other disputing the likeness of things that are. One ought,
therefore, to try oneself to coin a word to cover all things of the
given sort, so as to leave no opportunity either to the answerer to
dispute, and say that the thing advanced does not answer to a like
description, or to the questioner to suggest falsely that it does
answer to a like description, for many things appear to answer to like
descriptions that do not really do so.
If one has made an induction on the strength of several cases and
yet the answerer refuses to grant the universal proposition, then it
is fair to demand his objection. But until one has oneself stated in
what cases it is so, it is not fair to demand that he shall say in
what cases it is not so: for one should make the induction first,
and then demand the objection. One ought, moreover, to claim that
the objections should not be brought in reference to the actual
subject of the proposition, unless that subject happen to be the one
and only thing of the kind, as for instance two is the one prime
number among the even numbers: for, unless he can say that this
subject is unique of its kind, the objector ought to make his
objection in regard to some other. People sometimes object to a
universal proposition, and bring their objection not in regard to
the thing itself, but in regard to some homonym of it: thus they argue
that a man can very well have a colour or a foot or a hand other
than his own, for a painter may have a colour that is not his own, and
a cook may have a foot that is not his own. To meet them, therefore,
you should draw the distinction before putting your question in such
cases: for so long as the ambiguity remains undetected, so long will
the objection to the proposition be deemed valid. If, however, he
checks the series of questions by an objection in regard not to some
homonym, but to the actual thing asserted, the questioner should
withdraw the point objected to, and form the remainder into a
universal proposition, until he secures what he requires; e.g. in
the case of forgetfulness and having forgotten: for people refuse to
admit that the man who has lost his knowledge of a thing has forgotten
it, because if the thing alters, he has lost knowledge of it, but he
has not forgotten it. Accordingly the thing to do is to withdraw the
part objected to, and assert the remainder, e.g. that if a person have
lost knowledge of a thing while it still remains, he then has
forgotten it. One should similarly treat those who object to the
statement that '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 w
hen 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