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

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CHAPTER VI.
THE PREDICABLES, DEFINITION, AND CLASSIFICATION.
Part I. The Predicates.
i. THE Predicables are the various possible relations,
in extension and intension, which the predicate of a
proposition may bear to its subject, when it makes an
affirmation of the subject. In order to understand the
doctrine of the
"
"
Predicables in modern Logic, we
must have a clear idea of the way in which Aristotle
dealt with it. His object was (Topics, I. ch. 4, 5, 6)
first to classify these relations.
This may be done either inductively (&LCL TT}? eVa-
7&>7%), by examining every kind of proposition ; or
deductively (Sia (rv\\oyta~/jiov), by considering what
an affirmative proposition means to say i.e., the rela
tions (of predicate to subject) which it admits of if it is
to be an affirmative proposition at all. Let us adopt
the latter plan. The terms standing as Subject and
Predicate are either convertible in the Aristotelian sense,
without changing the meaning of the proposition, or they
are not i.e., they are or are not exclusively applicable to
the same things.
(i) If they are convertible this is equivalent to saying
that the extension of the two terms is the same. When
P thus coincides with 5 in extension, it may either (a)