Which set consists of the four categories of opposition?

• A. Causation, Correlation, Equivalence, Opposition
• B. Direct, Indirect, Conditional, Biconditional
• C. Contradictory, Contrary, Subcontrary, Subalternate
• D. Affirmative, Negative, Universal, Particular

Answer: (C)

The idea here is how two categorical propositions with the same terms relate to each other in opposition. There are four classic relations: contrary, subcontrary, contradictory, and subalternate.

• Contraries pair universal propositions (All S are P and No S are P). They cannot both be true, but they can both be false.

• Subcontraries pair particular propositions (Some S are P and Some S are not P). They cannot both be false, but they can both be true.

• Contradictories pair universal with particular of the opposite quality (All S are P with Some S are not P, and No S are P with Some S are S are P). They cannot both be true or both be false.

• Subalternation links universal to particular of the same quality (All S are P implies Some S are P, and No S are P implies Some S are not P). Truth flows downward from the universal to the particular, but not the other way.

That set—Contradictory, Contrary, Subcontrary, Subalternate—is the one that captures the four opposition relations. The other options refer to different concepts (causation/correlation, types of implication, or proposition quality and scope) rather than the specific four ways propositions can oppose each other.