Logical syllogism — determine which conclusions follow beyond doubt. Statements: 1) Some pens are books. 2) Some books are pencils. Conclusions: (1) Some pens are pencils. (2) Some pencils are pens. (3) All pencils are pens. (4) All books are pens.
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AOnly (1) and (3)
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BOnly (2) and (4)
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CAll the four
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DNone of the four
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EOnly (1)
Answer
Correct Answer: None of the four
Explanation
Introduction / Context: From two independent “Some …” premises, we must avoid inferring intersections that are not guaranteed. This is a common trap in syllogisms.
Given Data / Assumptions:
- Some pens overlap books.
- Some books overlap pencils.
- No information connects the same book elements across both statements.
Concept / Approach: Separate “Some” overlaps through a middle term (books) do not force an overlap between pens and pencils. Universal conclusions require universal premises, which are absent here.
Step-by-Step Solution: (1) “Some pens are pencils” — could be true, but not necessary. The set of books that are pens might differ from the set of books that are pencils. (2) “Some pencils are pens” — equivalent to (1), still not necessary. (3) “All pencils are pens” — far stronger than warranted. (4) “All books are pens” — not implied since only “Some pens are books” is given.
Verification / Alternative check: Counterexample: Let books = {b1, b2}; pens∩books = {b1}; pencils∩books = {b2}. Then both premises hold, but pens and pencils do not intersect. Thus none of the conclusions is forced.
Why Other Options Are Wrong: Options with (1) or (2) assume an intersection that need not exist. Options with (3) or (4) falsely universalize.
Common Pitfalls: Misapplying transitivity to “Some” statements and inferring universals from particulars.
Final Answer: None of the four