If two propositions having the same subject and predicate terms can both be…
2014
If two propositions having the same subject and predicate terms can both be true but cannot both be false, the relation between those two propositions is called:
Answer: C. subcontrary — ConceptThe traditional square of opposition classifies relations among the four standard categorical forms: A (universal affirmative), E (universal negative),…
- A.
contradictory
- B.
contrary
- C.
subcontrary
- D.
subaltern
Show answer & explanation
Correct answer: C
Concept
The traditional square of opposition classifies relations among the four standard categorical forms: A (universal affirmative), E (universal negative), I (particular affirmative), and O (particular negative). A relation is identified by whether its pair can be true together and whether it can be false together.
Application
The stem permits both propositions to be true together.
The stem rules out both propositions being false together.
Among the four relations, this truth-value pattern belongs to subcontrariety, the relation between I (“Some S are P”) and O (“Some S are not P”).
Cross-check and contrast
Contradiction: A–O and E–I pairs can be neither true together nor false together.
Contrariety: A–E can be false together but cannot be true together.
Subalternation: A implies I and E implies O under the traditional existential reading; it is not defined by the two-way pattern in the stem.
Therefore, the relation described is subcontrary.