Which of the following statements are so related that they cannot both be false, though they can both be true?

1.Some saints are materialists

2.All saints are materialists

3.No saints are materialists

4.Some saints are not materialists

AI and III only

BI and IV only ✓ Correct

CIII and IV only

DII and IV only

Correct answer: (B) I and IV only

Explanation

Statement 1 and Statement 4 are sub-contraries and are the pair sought.

The relation permits both being true but forbids both being false.

Statement 1 is the particular affirmative, Statement 4 the particular negative.

On the square of opposition the two particular propositions are sub-contraries.

At least one of the two must be true, so they cannot both be false.

This matches exactly the sub-contrary relation described.

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