An introductory text-book of logic - Mellone, Sydney - Rare Books at ...

THE GENERAL NATURE OF INDUCTION. 235
all in fig. i. ; but, having only a probable major premise,
they have only a probable conclusion. The best illustra
tions of the
"
"
sign (ari^elov) are medical ; the word
the arj^elov being the
might be rendered "symptom,"
symptom from which the physician makes his diagnosis.
To state it more generally, the
"
"
sign
is a fact which is
some other fact. The two facts
found to accompany
may go together in time, as when the carnivorous habits
of certain animals are a sign of great ferocity and
strength ; or one may follow the other, as lightning and
thunder may be signs of one another. The union of
the two facts may have all degrees of probability, from
absolute necessity down to the most groundless opinion,
as when the flight of birds is taken to be a sign of
coming events. The conclusion of course cannot be
more certain than the sign.
The forms of the enthymeme correspond to the three
figures of the syllogism. We begin with the third figure.
In conversation and writing, one of the premises is
frequently omitted, as in all obvious.
arguments,
when it is
(a) In the third figure, the enthymeme gives an
"
Wise men
instance of an accepted or suggested rule :
are good, for Pittakos is
Stated in full, this becomes :
Pittakos is good ;
Pittakos is wise ;
Example i.
good" (Aristotle, loc.
Therefore wise men are good (i.e., the individual
instance of Pittakos is the sign from which we
/.).
infer a real connection between the two qualities
which he possesses).
What we are usually inclined to do in such a case is to