Logical Reasoning

PT109 · S1 · Q23 An air traveler in Beijing

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

  • Save & drill this skill — build targeted practice sets from questions like this one

  • Video walkthroughs — watch every question solved step by step

  • 81 official LSATs — as questions, timed sections & full-length tests

Start practicing free

An air traveler in Beijing cannot fly to Lhasa without first flying to Chengdu.

Conclusion (therefore)

Lhasa requires Xian (anyone who flies from Beijing to Lhasa cannot avoid flying to Xian).

Evidence

Lhasa requires Chengdu (cannot fly to Lhasa from Beijing without first flying to Chengdu).

Chengdu requires Xian (must fly to Xian before flying to Chengdu).

Evaluate

Parallel questions usually involve conditional logic, and when they do, we lean towards diagramming them symbolically to see their form.

The conditional arrow can be read as "requires", so when we have two premises telling us essentially that L requires C and that C requires X, we get a chain.

P: L → C P: C → X

Those chain together to show L → C → X

The conclusion is just giving us the head to tail connection of that chain: L → X

Goal

We want two conditional premises that chain together, and a conclusion that shows the head to tail connection of the chain.

P: A → B P: B → C C: A → C

23.

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

  1. A doctor cannot prescribe porozine

    Bad Validity Match

    The first premise is a conditional, saying porozine requires anthroxine. P → A But the second premise is not conditional, since it only talks about "most" patients. We could stop reading there. If we were trying to make a valid conclusion we could say, "if you're taking porozine, you'll likely get drowsy or nervous" The conclusion also messes that up, by failing to consider the drowsy option.

    2% picked this

  2. Correct

    An ice-sculpture artist cannot reach

    Why this is right

    Yellow requires green. Green requires white. So, Yellow requires white. This matches our original structure. P: A → B P: B → C C: A → C

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

    91% picked this

  3. One cannot properly identify a

    Bad Conclusion Match

    The first premise gives a necessary condition (examining spores is necessary for proper identification). But we can't chain onto that with another requirement. The second premise says a powerful microscope can be used (sufficient, not necessary). If the second premise said, "In order to examine spores, you need a powerful microscope", then the answer would have worked.

    4% picked this

  4. It is impossible to be

    Bad Conclusion Match

    The first premise is a necessary condition (knowing rules is needed for fluency). The second premise could chain onto that, because there are two ways to learn the rules. P: Fluent → Know Gram P: Know Gram → Study or Upbringing We'd definitely be giving the second premise some side eye since the outcome has an OR, which the original argument didn't have. But the fundamental logical essence of the original argument would still work if the conclusion said, C: Fluent → Study or Upbringing. The conclusion vaguely alludes to there being two major ways, but it doesn't spell them out or make it seem like they are required. So even if we were being charitable up to this point, the conclusion is too far from what we want.

    1% picked this

  5. In the City Ballet Company

    Bad Validity Match

    The first premise is conditional, but the second once isn't ("some"). So we can't chain these two premises together to get a conditional chain, the way we could in the original argument.

    2% picked this

Continue the review in LSAT Lab

Save this question, watch the video walkthrough, and drill similar questions in your LSAT Lab account.

Save and practice this skill
LSAT Lab

Turn this review into a targeted study plan.

Save this question, drill more like it, watch the video walkthrough, and track your progress in your LSAT Lab account.

Start practicing free