That the Minor must be affirmative is evident, for if it were negative, the conclusion must be negative (Canon V.) and the Major Premiss must be affirmative (Canon IV.), and this would involve illicit process of the Major, P being distributed in the conclusion and not in the Premisses.
These two special rules leave only four possible valid forms in the First Figure. There are sixteen possible combinations of premisses, each of the four types of proposition being combinable with itself and with each of the others.
| AA AE AI AO | EA EE EI EO | IA IE II IO | OA OE OI OO |
Special Rule I. wipes out the columns on the right with the particular major premisses; and AE, EE, AO, and EO are rejected by Special Rule II., leaving BArbArA, CElArEnt, DArII and FErIO.
II. In the Second Figure, only Negative Moods are possible, and the Major Premiss must be universal.
Only Negative moods are possible, for unless one premiss is negative, M being the predicate term in both—
P in M
S in M—
is undistributed.