Logical ReasoningDifficulty: Hard

PT138 S3 Q24 Explanation

In the Riverview Building

A free, expert breakdown of this official LSAT Logical Reasoning question.

TopicsParallel Flaw

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Full official LSAT questions are available through LawHub. This page provides LSAT Lab's explanation, strategy, and review tools without republishing the full official question.

Stimulus

In the Riverview Building, every apartment that has a balcony also has a fireplace. None of the apartments with balconies is a one-bedroom apartment. one-bedroom apartments has a fireplace.

What this question is testing

Parallel Flaw

Your task

Break the argument into its conclusion and evidence, then do exactly what the question stem asks with that structure.

Common trap

Answers that sound relevant to the topic but don't connect to the argument's actual reasoning.

Winning move

Predict what a right answer must do, then test each choice against the conclusion-evidence gap.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
24.

The flawed nature of the argument above can most effectively be demonstrated by noting that, by parallel reasoning,

Answer choices

  1. Bad Conclusion Match6% picked this

    every fish has fur since no cat lacks fur and no cat

    We do have two conditional premises with the same trigger: Cat → Fur Cat → ~Fish The conclusion does create an illicit conditional relationship, but it isn't between those two outcomes. To match the original, we'd want to see a conclusion look like: Fur → ~Fish or Fish → ~Fur Instead, we get Fish → Fur A matching conclusion would have sounded like, "Nothing with fur is a fish".

  2. Bad Conclusion Match3% picked this

    some cats lack fur since every dog has fur and no cat

    The original conclusion was conditional, so the correct answer's conclusion should also be. This conclusion, meanwhile, is a Some statement.

  3. Correct66% picked this

    no dog has fur since every cat has fur and no cat

    Why this is right

    We have two conditional premises (an All and a No), with the same trigger: Cat → Fur Cat → ~Dog And we have a conclusion that builds a No conditional relationship between them: Dog → ~Fur

    Skill tested: Parallel Flaw · how this choice captures the argument's function is the move to repeat next time.

  4. Weak Premise/Conclusion Match17% picked this

    every cat is a fish since no cat is a dog and no dog

    If we wanted to, we could make both conditional premises have the same trigger: Dog → ~Cat Dog → ~Fish But (C) is already a better match, since it better replicated the mix of All and No premises we had in the original. The conclusion of this argument does create a conditional relationship between the outcomes, but it is an All relationship, whereas the original was a No relationship.

  5. Bad Premise Match Valid Logic8% picked this

    no fish is a dog since every dog is a mammal and no fish

    We do not have two conditionals with the same trigger. We can put Mammal on both sides, but we have a positive and a negative version, so it doesn't match. ~Mammal → ~Dog Mammal → ~Fish So there's no reason to keep reading this one. If we did, however, we would see that it's actually valid logic.

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