3 DEC SS Q.10
- Option : B
- Explanation : Observe the following traditional square of opposition.
The theses shown in the square were supplemented with the following:
• Two propositions are contradictory iff they cannot both be true and they cannot both be false.
• Two propositions are contraries iff they cannot both be true but can both be false.
• Two propositions are subcontraries iff they cannot both be false but can both be true.
• A proposition is a subaltern of another iff it must be true if its superaltern is true, and the superaltern must be false if the subaltern is false.
[iff = if and only if]
