Rhetoric   

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 into
examples, in order to show what is not yet known, that Dionysius has
the same purpose in making the same request: all these being instances
of the one general principle, that a man who asks for a bodyguard is
scheming to make himself a despot. We have now described the sources
of those means of persuasion which are popularly supposed to be
demonstrative.
There is an important distinction between two sorts of enthymemes that
has been wholly overlooked by almost everybody-one that also subsists
between the syllogisms treated of in dialectic. One sort of enthymeme
really belongs to rhetoric, as one sort of syllogism really belongs to
dialectic; but the other sort really belongs to other arts and
faculties, whether to those we already exercise or to those we have
not yet acquired. Missing this distinction, people fail to notice that
the more correctly they handle their particular subject the further
they are getting away from pure rhetoric or dialectic. This statement
will be clearer if expressed more fully. I mean that the proper
subjects of dialectical and rhetorical syllogisms are the things with
which we say the regular or universal Lines of Argument are concerned,
that is to say those lines of argument that apply equally to questions
of right conduct, natural science, politics, and many other things
that have nothing to do with one another. Take, for instance, the line
of argument concerned with 'the more or less'. On this line of
argument it is equally easy to base a syllogism or enthymeme about any
of what nevertheless are essentially disconnected subjects-right
conduct, natural science, or anything else whatever. But there are
also those special Lines of Argument which are based on such
propositions as apply only to particular groups or classes of things.
Thus there are propositions about natural science on which it is
impossible to base any enthymeme or syllogism about ethics, and other
propositions about ethics on which nothing can be based about natural
science. The same principle applies throughout. The general Lines of
Argument have no special subject-matter, and therefore will not
increase our understanding of any particular class of things. On the
other hand, the better the selection one makes of propositions
suitable for special Lines of Argument, the nearer one comes,
unconsciously, to setting up a science that is distinct from dialectic
and rhetoric. One may succeed in stating the required principles, but
one's science will be no longer dialectic or rhetoric, but the science
to which the principles thus discovered belong. Most enthymemes are in