The Complete Aristotle (eng.)

prize is a crown, it is enough to say ‘For he has
been victor in the Olympic games’, without adding ‘And in the
Olympic games the prize is a crown’, a fact which everybody
knows.
    There are few facts of the ‘necessary’ type that can form the
basis of rhetorical syllogisms. Most of the things about which we
make decisions, and into which therefore we inquire, present us
with alternative possibilities. For it is about our actions that we
deliberate and inquire, and all our actions have a contingent
character; hardly any of them are determined by necessity. Again,
conclusions that state what is merely usual or possible must be
drawn from premisses that do the same, just as ‘necessary’
conclusions must be drawn from ‘necessary’ premisses; this too is
clear to us from the Analytics. It is evident, therefore, that the
propositions forming the basis of enthymemes, though some of them
may be ‘necessary’, will most of them be only usually true. Now the
materials of enthymemes are Probabilities and Signs, which we can
see must correspond respectively with the propositions that are
generally and those that are necessarily true. A Probability is a
thing that usually happens; not, however, as some definitions would
suggest, anything whatever that usually happens, but only if it
belongs to the class of the ‘contingent’ or ‘variable’. It bears
the same relation to that in respect of which it is probable as the
universal bears to the particular. Of Signs, one kind bears the
same relation to the statement it supports as the particular bears
to the universal, the other the same as the universal bears to the
particular. The infallible kind is a ‘complete proof’ (tekmerhiou);
the fallible kind has no specific name. By infallible signs I mean
those on which syllogisms proper may be based: and this shows us
why this kind of Sign is called ‘complete proof’: when people think
that what they have said cannot be refuted, they then think that
they are bringing forward a ‘complete proof’, meaning that the
matter has now been demonstrated and completed (peperhasmeuou); for
the word ‘perhas’ has the same meaning (of ‘end’ or ‘boundary’) as
the word ‘tekmarh’ in the ancient tongue. Now the one kind of Sign
(that which bears to the proposition it supports the relation of
particular to universal) may be illustrated thus. Suppose it were
said, ‘The fact that Socrates was wise and just is a sign that the
wise are just’. Here we certainly have a Sign; but even though the
proposition be true, the argument is refutable, since it does not
form a syllogism. Suppose, on the other hand, it were said, ‘The
fact that he has a fever is a sign that he is ill’, or, ‘The fact
that she is giving milk is a sign that she has lately borne a
child’. Here we have the infallible kind of Sign, the only kind
that constitutes a complete proof, since it is the only kind that,
if the particular statement is true, is irrefutable. The other kind
of Sign, that which bears to the proposition it supports the
relation of universal to particular, might be illustrated by
saying, ‘The fact that he breathes fast is a sign that he has a
fever’. This argument also is refutable, even if the statement
about the fast breathing be true, since a man may breathe hard
without having a fever.
    It has, then, been stated above what is the nature of a
Probability, of a Sign, and of a complete proof, and what are the
differences between them. In the Analytics a more explicit
description has been given of these points; it is there shown why
some of these reasonings can be put into syllogisms and some
cannot.
    The ‘example’ has already been described as one kind of
induction; and the special nature of the subject-matter that
distinguishes it from the other kinds has also been stated above.
Its relation to the proposition it supports is not that of part to
whole, nor whole to part, nor whole to whole, but of part to part,
or like to like. When two statements are of the same order, but one
is more familiar than the other, the former is an ‘example’. The
argument may, for instance, be that Dionysius, in asking as he does
for a bodyguard, is scheming to make himself a despot. For in the
past Peisistratus kept asking for a bodyguard in order to carry out
such a scheme, and did make himself a despot as soon as he got it;
and so did Theagenes at Megara; and in the same way all other
instances known to the speaker are made