PrepTest 115

[lcid:3557] Prep Test 115 LSAT — Logical Reasoning — S2 Logical reasoning

Question prompt

All historians are able Remaining source text redacted.
Why the credited answer is right

Credited answer: A

The notes below walk through why it fits the stem and how to eliminate the rest.

Question Type

Flawed Parallel Reasoning Questions / Sufficient & Necessary Questions

Answer choices

  1. A
    All expressions used for Remaining source text redacted.
    Why choice A matches the stem
    Correct. Argument or Facts:
    Argument

    Valid or Flawed:
    Flawed

    Question Type:
    Flawed Parallel Reasoning

    Stimulus Summary:
    Historian → Spot trend
    Spot trend → Distinguish significant from insignificant
    Therefore - Distinguish significant from insignificant → Historian

    Answer Anticipation:
    This argument has two conditional premises that chain together, and a conditional conclusion that's the illegal reversal of that chain. It's pretty run-of-the-mill, so we're expecting the answers to be made up of conditional statements that will require us to work through the diagrams in order to make eliminations, since this is a question #18 and can't possibly be that straightforward!

    A → B
    B → C
    Therefore - C → A

    Answer Explanation:
    Expression for emo impact → Used by poet
    Figure of speech → Expression for emo impact
    Therefore - Used by poet → Figure of speech
    While this answer presents the premises/conclusion in a different order than the stimulus, that's not relevant to the logic. Here, there are two conditional premises that chain together, and a conclusion that's the reversal of that chain, so this is the correct answer.

    Key Takeaway:
    When an argument falls into a common conditional flaw, look for elements that don't match up with that flaw in Flawed Parallel Reasoning answers. You can frequently get away with not diagramming out each answer if you can identify such an element!
  2. B
    Political systems whose laws Remaining source text redacted.
    Why choice B is not credited
    Incorrect. This answer has a new concept in the conclusion ("not run by autocrats"), causality ("leads to"), and different certainty than the stimulus ("tends to"), so we can rule it out.
  3. C
    Animals that possess horns Remaining source text redacted.
    Why choice C is not credited
    Incorrect. The premises here all have elements that are missing from the stimulus (OR statements, statements ruling out one possibility in favor of another), so we can eliminate it.
  4. D
    No one without a Remaining source text redacted.
    Why choice D is not credited
    Incorrect. This answer does have conditional premises, but the conclusion is about what short-story writers could . . . have become, so the logical force is off from the stimulus.
  5. E
    People living in open Remaining source text redacted.
    Why choice E is not credited
    Incorrect. Being entirely free is a new concept raised in the conclusion here, so it has a different flaw than the stimulus.

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