The Four Forms, Upgraded
This video presents the same text shown beside it, spoken and on screen. It adds nothing the text does not say.
State
A: (x)(Sx ⊃ Px). E: (x)(Sx ⊃ ~Px). I: (∃x)(Sx · Px). O: (∃x)(Sx · ~Px).
Show
Unit 3's four forms, rewritten in the finer notation.
Watch for
Note the pattern — universals pair with ⊃, existentials with ·. That pairing is a law, and the next-but-one video explains it.