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Difficulty: MediumParallel Reasoning and Parallel Flaw

Medical Director: Any pharmaceutical trial that demonstrates statistical significance requires a sample size exceeding five hundred patients. Most oncology research initiatives conducted at the university hospital require a sample size exceeding five hundred patients. Therefore, most oncology research initiatives conducted at the university hospital demonstrate statistical significance.

Which of the following arguments exhibits a pattern of flawed reasoning most similar to that exhibited by the argument above?

  1. A
    Any regional airport that operates scheduled international routes must maintain on-site customs facilities. Most coastal airfields maintain on-site customs facilities. Therefore, all coastal airfields must operate scheduled international routes.
  2. B
    Any clinical trial testing a novel synthetic vaccine must receive formal clearance from the institutional ethics board. The pending pediatric trial did not receive formal clearance from the institutional ethics board. Therefore, the pending pediatric trial cannot test a novel synthetic vaccine.
  3. Any architectural proposal that qualifies for the civic sustainability grant must include a rainwater reclamation system. Most urban redevelopment blueprints submitted this year include a rainwater reclamation system. Thus, most urban redevelopment blueprints submitted this year qualify for the civic sustainability grant.Answer
  4. D
    Any high-speed rail corridor that meets regional transit objectives must connect at least three metropolitan centers. The northern corridor does not meet regional transit objectives. Therefore, the northern corridor cannot connect at least three metropolitan centers.
  5. E
    Any novel published by a major trade imprint must undergo extensive professional copyediting. This newly submitted manuscript underwent extensive professional copyediting. Consequently, this newly submitted manuscript must be a novel published by a major trade imprint.

Answer

The argument asserting that most urban redevelopment blueprints qualify for the civic sustainability grant because they include a rainwater reclamation system.
The correct argument exhibits the exact same formal skeleton and logical flaw as the stimulus: it sets up a universal conditional requirement (qualifying for the grant requires a rainwater reclamation system), asserts that 'most' members of a subset possess that required feature, and invalidly concludes that 'most' members of that subset therefore satisfy the sufficient condition (qualifying for the grant).

Step-by-Step Solution

1
Analyze the formal structure and quantifiers of the stimulus argument.
Premise 1 establishes a conditional rule: If a trial demonstrates statistical significance, then it requires >500 patients (Significant → >500). Premise 2 states a quantifier relationship: Most oncology initiatives require >500 patients (Most Oncology → >500). Conclusion draws an invalid quantifier inference: Most oncology initiatives demonstrate statistical significance (Most Oncology → Significant).
Deconstructing the argument into symbolic logic reveals the underlying structural defect.
2
Identify the specific logical defect (flaw).
The argument commits a quantifier-based affirming-the-consequent flaw: having >500 patients is merely a necessary condition for statistical significance, not a sufficient one. One cannot conclude that because 'most' members of a subset possess the necessary feature, 'most' satisfy the sufficient condition.
Isolating the precise logical flaw allows matching it to the correct structurally isomorphic answer choice.
3
Evaluate the choices to find the argument with identical premises, quantifiers, and logical flaw.
The argument concerning architectural proposals states: Qualify for Grant → Rainwater System; Most Blueprints → Rainwater System; Therefore, Most Blueprints → Qualify for Grant. This matches the conditional necessity, quantifier ('most'), and invalid inference step-for-step.
Parallel reasoning questions require an exact match in logical skeleton and quantifier strength.

Key Concept

Parallel Flaw: Illicit Quantifier Overlap and Affirming a Necessary Condition
Estimated Time:1m 30s
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Topics

Parallel Reasoning and Parallel Flaw

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