Proof: (1) If the major premise is affirmative, then its predicate which is the middle term, M, is undistributed; for no affirmative distributes its predicate.
(2) The middle term must then be distributed in the “minor” according to rule 3.
(3) Then the “minor” must be universal; since only universals distribute their subjects.
Problem: To prove that if the minor is affirmative, the conclusion must be particular.
Data: Given the form of the fourth figure:
G — M
M — S
S — G
Proof: (1) If the minor premise be affirmative, then S, its predicate, must be undistributed; because no affirmative distributes its predicate.
(2) Since S is undistributed in the minor premise, it must remain undistributed in the conclusion where it is used as the subject.