The Complete Aristotle (eng.)

make
use, more or less, of both; for to a certain extent all men attempt
to discuss statements and to maintain them, to defend themselves
and to attack others. Ordinary people do this either at random or
through practice and from acquired habit. Both ways being possible,
the subject can plainly be handled systematically, for it is
possible to inquire the reason why some speakers succeed through
practice and others spontaneously; and every one will at once agree
that such an inquiry is the function of an art.
    Now, the framers of the current treatises on rhetoric have
constructed but a small portion of that art. The modes of
persuasion are the only true constituents of the art: everything
else is merely accessory. These writers, however, say nothing about
enthymemes, which are the substance of rhetorical persuasion, but
deal mainly with non-essentials. The arousing of prejudice, pity,
anger, and similar emotions has nothing to do with the essential
facts, but is merely a personal appeal to the man who is judging
the case. Consequently if the rules for trials which are now laid
down some states-especially in well-governed states-were applied
everywhere, such people would have nothing to say. All men, no
doubt, think that the laws should prescribe such rules, but some,
as in the court of Areopagus, give practical effect to their
thoughts and forbid talk about non-essentials. This is sound law
and custom. It is not right to pervert the judge by moving him to
anger or envy or pity-one might as well warp a carpenter’s rule
before using it. Again, a litigant has clearly nothing to do but to
show that the alleged fact is so or is not so, that it has or has
not happened. As to whether a thing is important or unimportant,
just or unjust, the judge must surely refuse to take his
instructions from the litigants: he must decide for himself all
such points as the law-giver has not already defined for him.
    Now, it is of great moment that well-drawn laws should
themselves define all the points they possibly can and leave as few
as may be to the decision of the judges; and this for several
reasons. First, to find one man, or a few men, who are sensible
persons and capable of legislating and administering justice is
easier than to find a large number. Next, laws are made after long
consideration, whereas decisions in the courts are given at short
notice, which makes it hard for those who try the case to satisfy
the claims of justice and expediency. The weightiest reason of all
is that the decision of the lawgiver is not particular but
prospective and general, whereas members of the assembly and the
jury find it their duty to decide on definite cases brought before
them. They will often have allowed themselves to be so much
influenced by feelings of friendship or hatred or self-interest
that they lose any clear vision of the truth and have their
judgement obscured by considerations of personal pleasure or pain.
In general, then, the judge should, we say, be allowed to decide as
few things as possible. But questions as to whether something has
happened or has not happened, will be or will not be, is or is not,
must of necessity be left to the judge, since the lawgiver cannot
foresee them. If this is so, it is evident that any one who lays
down rules about other matters, such as what must be the contents
of the ‘introduction’ or the ‘narration’ or any of the other
divisions of a speech, is theorizing about non-essentials as if
they belonged to the art. The only question with which these
writers here deal is how to put the judge into a given frame of
mind. About the orator’s proper modes of persuasion they have
nothing to tell us; nothing, that is, about how to gain skill in
enthymemes.
    Hence it comes that, although the same systematic principles
apply to political as to forensic oratory, and although the former
is a nobler business, and fitter for a citizen, than that which
concerns the relations of private individuals, these authors say
nothing about political oratory, but try, one and all, to write
treatises on the way to plead in court. The reason for this is that
in political oratory there is less inducement to talk about
nonessentials. Political oratory is less given to unscrupulous
practices than forensic, because it treats of wider issues. In a
political debate the man who is forming a judgement is making a
decision about his own vital interests. There is no need,
therefore, to prove anything except that the facts