Syllogism — Envelopes, Gums, Seals, and Adhesives Statements: • Some envelopes are gums. • Some gums are seals. • Some seals are adhesives. Conclusions: (1) Some envelopes are seals. (2) Some gums are adhesives. (3) Some adhesives are seals. (4) Some adhesives are gums.

Difficulty: Medium

Correct Answer: Only (3)

Explanation:


Introduction / Context:
This problem asks which conclusions necessarily follow given three “some” statements across four categories. With “some,” overlaps are possible but not guaranteed unless directly stated or logically converted.


Given Data / Assumptions:

  • E = envelopes, G = gums, S = seals, A = adhesives.
  • Premises: Some E are G; Some G are S; Some S are A.
  • Conclusions to test: (1) Some E are S; (2) Some G are A; (3) Some A are S; (4) Some A are G.


Concept / Approach:
Only conclusions that must be true in every diagram consistent with the premises are valid. From “Some S are A,” we can apply conversion for “some”: “Some A are S.” Other claimed overlaps require the same individuals to be shared across different “some” statements, which is not forced.


Step-by-Step Solution:

(3) Some adhesives are seals: Directly from “Some seals are adhesives,” convert to “Some adhesives are seals.” Valid.(1) Some envelopes are seals: We have E∩G ≠ ∅ and G∩S ≠ ∅, but the overlapping members of G in each statement need not be the same element. So E∩S may be empty. Not guaranteed.(2) Some gums are adhesives: Similarly, S∩A ≠ ∅ and G∩S ≠ ∅ do not force G∩A ≠ ∅. Not guaranteed.(4) Some adhesives are gums: Again, nothing compels A to overlap with G.


Verification / Alternative check:
Construct a counterexample: place one item in E∩G; a different item in G∩S; and another in S∩A. All premises hold while E∩S, G∩A, and E∩A remain empty. Thus only (3) must follow.


Why Other Options Are Wrong:

  • (1), (2), (4) each assumes compelled overlap among different “some” statements. This is not logically necessary.
  • Only (3) is the unique must-follow conclusion.


Common Pitfalls:
Chaining “some” statements as if they behave like “all.” Remember: “some” + “some” does not compel intersection beyond what is explicitly stated.


Final Answer:
Only (3)

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