Which of the following statements is equivalent to the statement 'Some philosophers are not idealists'?

ASome philosophers are not non-idealists

BNo idealists are philosophers

CSome non-idealists are not philosophers

DSome non-idealists are not non-philosophers ✓ Correct

Correct answer: (D) Some non-idealists are not non-philosophers

Explanation

The equivalent is 'Some non-idealists are not non-philosophers'.

The given statement is an O proposition, some S are not P.

Contraposition is a valid immediate inference for O propositions.

It interchanges and negates both terms: the subject becomes non-P, the predicate non-S.

So 'some philosophers are not idealists' becomes 'some non-idealists are not non-philosophers'.

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