The Complete Aristotle (eng.)

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that kind a reference to another party is involved. Not so with the
philosopher, and the man who is investigating by himself: the
premisses of his reasoning, although true and familiar, may be
refused by the answerer because they lie too near the original
statement and so he foresees what will follow if he grants them:
but for this the 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