- Universal Affirmative (A statement) and Particular Negative (O statement) are logical opposites (contradictories) and cannot both be true, but can both be false.
Example: If “all dogs are mammals” is false, “some dogs are not mammals” is true, but not vice versa.
- Universal Negative (E statement) and Particular Affirmative (I statement) are logical opposites (contradictories) and cannot both be true, but can both be false.
Example: If “no birds can talk” is false, “some birds can talk” is true, but not vice versa.
- Universal Affirmative (A statement) and Universal Negative (E statement) are logical contradictories and cannot both be true, but can both be false.
Example: If “All crows are black” is false, then “No crows are black” is true, and vice versa.
- Particular Affirmative (I statement) and Particular Negative (O statement) cannot be logical contradictories, because both can be either true or false.
Example: If “some cars are red” (I statement) is false, then “some cars are not red” (O statement) is true, and vice versa.