Each categorical premise may have four basic quantity-and-quality forms:
Universal affirmative (A) — All A are B.
Universal negative (E) — No A are B.
Particular affirmative (I) — Some A are B.
Particular negative (O) — Some A are not B.
There are four possibilities for the minor and four for the major, giving 4 × 4 = 16 initial combinations. That counts arrangements, not valid inferences.
Opening interactive controls...
The First Figure: Conditions of Validity and Four Productive Moods
Each categorical premise may have four basic quantity-and-quality forms:
Universal affirmative (A) — All A are B.
Universal negative (E) — No A are B.
Particular affirmative (I) — Some A are B.
Particular negative (O) — Some A are not B.
There are four possibilities for the minor and four for the major, giving 4 × 4 = 16 initial combinations. That counts arrangements, not valid inferences.