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Difficulty: EasyParallel Reasoning and Parallel Flaw

Every member of the astronomy club attended the guest lecture. Jordan attended the guest lecture, so Jordan must be a member of the astronomy club.

The flawed pattern of reasoning in the argument above is most similar to that in which one of the following?

  1. A
    Every employee who meets their sales quota receives an annual bonus. Priya did not meet her sales quota, so Priya will not receive an annual bonus.
  2. B
    Every member of the astronomy club receives a monthly newsletter. Samantha is a member of the astronomy club, so Samantha receives a monthly newsletter.
  3. All certified lifeguards at the community pool know CPR. Marcus knows CPR, so Marcus must be a certified lifeguard at the community pool.Answer
  4. D
    Any student who completes the advanced seminar receives honors credit. Leo did not receive honors credit, so Leo did not complete the advanced seminar.
  5. E
    Most members of the cycling team train in the mornings. Mateo trains in the mornings, so Mateo must be a member of the cycling team.

Answer

The argument concluding that Marcus must be a certified lifeguard because all certified lifeguards know CPR and Marcus knows CPR.
The correct argument exhibits the identical Mistaken Reversal flaw: it starts from a universal rule ('All certified lifeguards know CPR'), confirms the presence of the necessary condition ('Marcus knows CPR'), and illicitly concludes that the sufficient condition must hold ('Marcus must be a certified lifeguard').

Step-by-Step Solution

1
Analyze the logical structure and validity of the stimulus.
Premise 1: Astronomy Club Member -> Attended Lecture. Premise 2: Jordan attended lecture. Conclusion: Jordan is an astronomy club member.
Deconstructing the argument reveals a classic Mistaken Reversal (Affirming the Consequent) where having a necessary condition is incorrectly treated as guaranteeing the sufficient condition.
2
Abstract the core flaw into a structural template.
All X are Y; Individual Z is Y; Therefore, Individual Z must be X.
A parallel flaw question requires matching the exact structural defect, including the certainty of the conclusion.
3
Evaluate the answer choices to identify the exact structural match.
The argument regarding certified lifeguards matches the template: All Lifeguards (X) know CPR (Y); Marcus (Z) knows CPR (Y); Therefore, Marcus (Z) is a Lifeguard (X).
Only this option replicates the exact invalid conditional reversal from an absolute universal premise.

Key Concept

Parallel Flaw - Mistaken Reversal (Affirming the Consequent)
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Topics

Parallel Reasoning and Parallel Flaw

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