Which of the following arrangements involve the fallacy of the irregular (undistributed) middle term?

1.Sound is a quality because it is visible

2.Sound is eternal because it is audible

3.Sound is eternal because it is produced

4.All things are non-eternal because they are knowable

A1, 2 & 3 only

B2 & 4 only ✓ Correct

C2 & 3 only

D1, 2 & 4 only

Correct answer: (B) 2 & 4 only

Explanation

Statements 2 and 4 carry the irregular middle that fails to be exclusively tied to the predicate.

In Statement 2 audibility belongs to sound alone and to nothing else, so it gives no positive parallel case and stays inconclusive.

In Statement 4 knowability belongs to everything, so no contrasting negative case exists to confine it either.

In both, the reason wanders and does not fix the conclusion, the mark of the inconclusive middle.

Statement 1 rests on an unreal reason and Statement 3 on a contradictory one, so only 2 and 4 show the irregular middle.

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