Part III, Chapter 2: Division of Syllogisms into Simple and Conjunctive
SYLLOGISMS are simple or conjunctive. The simple, are those in which the middle term is joined to only one of the terms of the conclusion at the same time; the conjunctive, are those in which it is joined to both. Thus this argument is simple: —
Every good prince is loved by his subjects; Every pious king is a good prince; Therefore every pious king is loved by his subjects; because the middle term is joined separately to pious king, which is the subject of the conclusion; and to be loved by his subjects, which is its attribute. But the following is conjunctive, for the opposite reason: —
If an elective state is subject to divisions, it is not of long duration;
Now an elective state is subject to divisions; Therefore an elective state is not of long duration; since elective state, which is the subject, and of long duration, which is the attribute, enter into the major proposition.
As these kinds of syllogisms have separate rules, we shall treat of them separately.
Simple syllogisms, which are those in which the middle term is joined separately with each term of the conclusion, are also of two sorts.
The one, in which each term is joined completely with the middle, to wit, with the whole attribute in the major, and with the whole subject in the minor.
The other, in which, the conclusion being complex, that is to say, composed of complex terms, we take only a part of the attribute, or a part of the subject, to join with the middle in one of the propositions, and all the rest, which forms only a single term, to join with the middle in the other proposition.
The divine law binds us to honour kings;
Louis XIV. is king;
Therefore the divine law binds us to honour Louis XIV.
We call the first kinds of arguments plain and incomplex, and the others involved or complex; not that all those in which there are complex propositions are of this last kind, but because there are none of this last kind in which there are not complex propositions.
Now, although the rules which are commonly given for simple syllogisms may hold in all complex syllogisms, by reversing them, nevertheless, as the strength of the conclusion does not depend on that inversion, we shall here apply the rules of simple syllogisms only to the incomplex, reserving complex syllogisms to be treated of separately.