Which of the following propositions are so related that they cannot both be…
2026
Which of the following propositions are so related that they cannot both be false though they can both be true?
A. All pitcher-plants are carnivores
B. No pitcher-plants are carnivores
C. Some pitcher-plants are carnivores
D. Some pitcher-plants are not carnivores
Choose the correct answer from the options given below:
- A.
A and C Only
- B.
A and D Only
- C.
B and C Only
- D.
C and D Only
Attempted by 13 students.
Show answer & explanation
Correct answer: D
The question asks for propositions that cannot both be false but can both be true.
This describes the subcontrary relationship in the Square of Opposition.
Proposition A is a Universal Affirmative (A-type). Proposition B is a Universal Negative (E-type).
Proposition C is a Particular Affirmative (I-type). Proposition D is a Particular Negative (O-type).
The subcontrary relationship exists between the I-proposition and the O-proposition.
Therefore, propositions C (Some pitcher-plants are carnivores) and D (Some pitcher-plants are not carnivores) cannot both be false, though they can both be true.