Which of the following statements is logically equivalent to the statement All philosophers are realists?

ANo philosopher is non-realist ✓ Correct

BNo realists are non-philosophers

CNo non-philosopher is non-realist

DNo non-realists are non-philosophers

Correct answer: (A) No philosopher is non-realist

Explanation

The equivalent proposition is no philosopher is non-realist.

The given proposition is the A form, all philosophers are realists.

Obversion changes the quality and replaces the predicate by its complement.

All philosophers are realists thus obverts to no philosopher is non-realist.

Obversion of an A proposition preserves logical equivalence.

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