Syllogism — mixing “some”, “no”, and a universal inclusion Statements: • Some towels are brushes. • No brush is soap. • All soaps are rats. Conclusions to evaluate: I. Some rats are brushes. II. No rat is brush. III. Some towels are soaps.

Difficulty: Easy

Correct Answer: None follows

Explanation:


Introduction / Context:
This question blends an existential overlap with a universal negative and a universal inclusion. The aim is to see whether any necessary relationship can be forced between brushes and rats or between towels and soaps.



Given Data / Assumptions:

  • T = towels, B = brushes, S = soaps, R = rats.
  • Some T are B.
  • No B is S.
  • All S are R.


Concept / Approach:
No B is S tells us brushes and soaps are disjoint. All S are R only places soaps inside rats; it does not say all rats are soaps. Therefore, brushes might still be rats (if there exist rats outside S) or might not be; the premises are silent. Also, nothing connects towels to soaps except through brushes, and brushes are explicitly not soaps.



Step-by-Step Solution:

Conclusion I (Some rats are brushes) is not forced. It would require B ∩ R to be nonempty. Since R may contain elements beyond S, the premises neither ensure nor forbid such an overlap.Conclusion II (No rat is brush) is also not compelled. The premises only deny B ∩ S, not B ∩ R. If R includes non-soap rats, brushes could be among those.Conclusion III (Some towels are soaps) fails because the only link from towels to soaps would go through brushes (some towels are brushes), yet no brush is a soap.


Verification / Alternative check:
Model A: Let S ⊆ R and R also contain r1 not in S. Let B = {r1} and some T include r1. Then I is true and II is false. Model B: Let B disjoint from R entirely, and T overlap B. Then II is true and I false. Since different valid models yield different truth values, none of I–III is necessary.



Why Other Options Are Wrong:

  • Only either I or II follows: although exactly one of them will be true in any single model, the premises do not force which one; therefore the disjunction is not a necessary consequence here.
  • Only II follows / Only I and III follow: each asserts claims that can fail under valid models.
  • None of these: option A already captures that no listed conclusion must hold.


Common Pitfalls:
Assuming all rats are soaps (converse of all S are R); trying to pass through the brush set to reach soaps despite the explicit exclusion.



Final Answer:
None follows

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