Statements: Some papers are pens. All the pencils are pens. Conclusions: (1)…

2024

Statements: Some papers are pens. All the pencils are pens.

Conclusions: (1) Some pens are pencils. (2) Some pens are papers.

  1. A.

    Only (1) conclusion follows

  2. B.

    Only (2) conclusion follows

  3. C.

    Both (1) and (2) follow

  4. D.

    Neither (1) nor (2) follows

Attempted by 288 students.

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Correct answer: C

Concept: A conclusion follows from a single categorical premise by conversion. Two rules apply here — (a) a particular affirmative, “Some X are Y”, converts simply to “Some Y are X”; (b) a universal affirmative, “All X are Y”, carries existential import under this convention and converts by limitation to the particular “Some Y are X” (valid whenever the subject class is assumed non-empty — the standard assumption for these syllogisms).

Application:

  1. Premise “Some papers are pens” is a particular affirmative. By simple conversion it directly yields “Some pens are papers” — this is conclusion (2), so it follows.

  2. Premise “All the pencils are pens” is a universal affirmative. By conversion with existential import, it yields “Some pens are pencils” — this is conclusion (1), so it also follows.

Cross-check: Take pens as the reference circle. “Some papers are pens” places an overlapping papers circle — that overlap region is exactly “some pens are papers.” “All the pencils are pens” places the pencils circle fully inside the pens circle; since the pencils circle is non-empty, that inclusion is itself the overlap needed for “some pens are pencils.” Both overlaps exist together in every valid diagram, confirming both conclusions independently.

Answer: Both conclusions follow.

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