Which of the following statements are logically equivalent?

1.No philosophers are industrialists

2.No industrialists are philosophers

3.All non-industrialists are non-philosophers

4.All philosophers are non-industrialists

A1, 2 & 3 only

B1, 2 & 4 only ✓ Correct

C1, 3 & 4 only

D2, 3 & 4 only

Correct answer: (B) 1, 2 & 4 only

Explanation

Statements 1, 2 and 4 all state the same universal negative about philosophers and industrialists.

Statement 1 is the universal negative No philosophers are industrialists.

Statement 2 is its converse, No industrialists are philosophers, valid for an E proposition.

Statement 4 is its obverse, All philosophers are non-industrialists, meaning preserved.

Statement 3 reduces to All philosophers are industrialists, the opposite claim, so it is excluded.

Conversion and obversion are the truth-preserving transformations of an E proposition.

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