
Aristotle’s logic is called
categorical logic.

what are the 4 standard form categorical claims
 All S are P
 No S are P
 Some S are P
 Some S are not P




Some S are not P letter
O

top left, top right, bottom left, bottom right letters?
A, E, I, O

left side of square
Affirmitive

Right side of square
Negative

Top Side of square
Universal

Bottom side of square
Particular

purpose of the square of opposition
To find the truth values of other categorical claims!

Relationship between E and I
Contradictories

Relationship between A and O
Contradictories

Relationship between A and E
Contraries

Relationship between I and O
Subcontraries

Rule of contraries
The universal claims can‟t both be True

Rule of contradictories
The diagonal claims have opposite Truth Value

Rule of subcontraries
The particular claims can‟t both be False

