Logical ReasoningDifficulty: Hard

PT21 S3 Q22 Explanation

Anatomical bilateral symmetry is

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

TopicsParallel

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Stimulus

Anatomical bilateral symmetry is a common trait. It follows, therefore, that it confers survival advantages on organisms. After all, if bilateral symmetry did not would not be common.

What this question is testing

Parallel

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
22.

The pattern of reasoning in which one of the following arguments is most similar to that in

Answer choices

  1. Bad Premise/Conclusion Match21% picked this

    Since it is Sawyer who is negotiating for the city government, it must be true that the city takes the matter seriously. After all,

    This provides a conditional premise, S wasn't available ? negotiations deferred So the other premise should trigger the contrapositive, by saying the opposite of the outcome: but the negotiations were not deferred Instead, the other premise said the opposite of the trigger: but S was available. We don't need any more reason to get rid of this one, but the Conclusion also happens to be bad, since it brings in a brand new concept (takes matter seriously) that was never even discussed in the premises.

  2. Bad Premise Match1% picked this

    Clearly, no candidate is better qualified for the job than Trumbull. In fact, even to suggest that there might be a more highly qualified

    This only has one premise (the original argument had two), so it really doesn't even get off the ground.

  3. Correct63% picked this

    If Powell lacked superior negotiating skills, she would not have been appointed arbitrator in this case. As everyone knows, she is the appointed arbitrator,

    Why this is right

    This provides a conditional premise, P lacked great ? wouldn't have been negotiating skills appointed arbitrator So the other premise should trigger the contrapositive, by saying the opposite of the outcome: P was appointed arbitrator. It does. So now the conclusion should be saying the opposite of the trigger: P does have superior negotiating skills. It does.

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

  4. Bad Premise/Conclusion Match9% picked this

    Since Varga was away on vacation at the time, it must have been Rivers who conducted the secret negotiations. Any other scenario makes little

    This provides a conditional premise, V is available ? R doesn't do negotiating So the other premise should trigger the contrapositive, by saying the opposite of the outcome: R does do negotiating Instead, that idea is found in the Conclusion. And the second premise says the opposite of the trigger: V was not available (he was on vacation)

  5. Bad Premise/Conclusion Match7% picked this

    If Wong is appointed arbitrator, a decision will be reached promptly. Since it would be absurd to appoint anyone other than Wong as arbitrator,

    This provides a conditional premise, W appointed arbitrator ? decision reached soon So the other premise should trigger the contrapositive, by saying the opposite of the outcome: but the decision will not be reached soon Instead, that idea shows up as the conclusion, and the other premise just affirms the trigger.

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