These relations can be pretty hard to keep track of. This is where the Square of Opposition, created in the Middle Ages but based on Aristotle’s findings, comes in handy. This diagram allows us to take note of all the relations simultaneously.
- In the diagram, Universal Affirmative propositions are labeled with the letter “A.” Universal Negative propositions are labeled with an “E.” Particular Affirmative propositions are labeled with an “I.” Particular Negative propositions are labeled with an “O.” These are all standard conventions.
- The different lines connecting these letters indicate the four types of relations listed above. Remember, though, the subaltern relation is only one way.