II. Rules three and four pertain to the distribution of terms.
III. Rules five and six have reference to negative premises.
IV. Rules seven and eight concern particular premises.
4. RULES OF THE SYLLOGISM EXPLAINED.
(1) A syllogism must have three and only three terms.
It is common to represent the various syllogistic forms by symbols, the same symbols always standing for the same terms. In this treatment we shall let capital G stand for the major term, as “major” means greater; capital S for the minor term, as “minor” means smaller, and capital M for the middle term. G, S and M, the initial letters of greater (major), smaller (minor) and middle, will be the constant symbols forthese terms; just as A, E, I and O are used as the constant symbols for the four logical propositions.
Illustration.
Syllogism written in full:
All men are mortal,
Socrates is a man,