Logical deduction – "all that flows have viscosity": Choose the correct implication or contrapositive pair. (i) It flows. (ii) It does not flow. (iii) It has viscosity. (iv) It does not have viscosity.
Verbal Reasoning
Logical Deduction
Difficulty: Easy
Choose an option
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A(iii) (i)
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B(iv) (ii)
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CBoth (i) and (ii)
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DNone
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EAll of these
Answer
Correct Answer: (iv) (ii)
Explanation
Introduction / Context:"All that flows have viscosity" is Flows ⇒ HasViscosity. The logically equivalent contrapositive is NotHasViscosity ⇒ NotFlows.
Given Data / Assumptions:
- If something flows, it must have viscosity.
- If it lacks viscosity, it cannot flow.
Concept / Approach:Option (iv) (ii) states the contrapositive pair: not having viscosity implies not flowing.
Step-by-Step Solution:
Flows ⇒ HasViscosity.Contrapositive: NotHasViscosity ⇒ NotFlows.Thus (iv) (ii) is valid.Verification / Alternative check:(iii) (i) incorrectly assumes HasViscosity ⇒ Flows (converse). Many solids have viscosity-defined properties but do not "flow" macroscopically.
Why Other Options Are Wrong:(iii) (i) is converse fallacy. (c) is meaningless as written. (d) is false.
Common Pitfalls:Reversing subset implications.
Final Answer:(iv) (ii)