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LSAT Explanations › Preptest 112 › Logical Reasoning › Question 14

LSAT 112 | Section 4 | Logical Reasoning: Q14

LSAT Preptest 112 explanations

LR Question 14 Explanation

QUESTION TEXT: Joseph: My encyclopedia says that the mathematician…

QUESTION TYPE: Flawed Reasoning

CONCLUSION: Laura concludes that Fermat was neither lying nor mistaken when he claimed to have proven the theorem.

REASONING: Someone else did prove the theorem (therefore it was possible to prove the theorem.)

ANALYSIS: Laura makes the mistake of assuming that since it was possible for Fermat to have proven the theorem then Fermat must have proven the theorem.

It is possible that Fermat didn’t actually prove the theorem, even though someone else did later.

___________

  1. The fact that someone did prove the theorem does not contradict the idea that Fermat did. In fact it shows its is possible that Fermat did prove it. It doesn’t make it certain that Fermat proved the theorem, of course.
  2. Laura hasn’t said anything about the quality of Fermat’s character.
  3. CORRECT. For Fermat to have proven the theorem it is necessary that it was possible. But the mere fact that it was possible doesn’t mean that Fermat actually did prove the theorem. 
  4. Everyone can figure out what provable means: possible to prove true.
  5. Laura doesn’t mention either of these two phenomena. Joseph made the mistake of thinking that a true claim (the theorem can be proven) was false, but that doesn’t have much to do with Laura’s reasoning. 
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More Resources for Flaw Questions

  • Flaw drills: Use these to practice making examples of abstract flaws.
  • Intro Course lesson: This intro course lesson covers Flaw questions.
  • Mastery Seminar lesson: This LR Mastery seminar lesson covers flaw questions.
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Comments

  1. Batman says

    April 30, 2019 at 8:37 pm

    I got this wrong. I knew what the problem was. That proving the theorem right, doesn’t mean that Fermat was not lying or mistaken.

    But, I had a hard time understanding the abstract language. I was stuck between “C” and “E,” didn’t understand what they both said, and wrongly chose “E.”

    Is there a way to get good at abstract language?

    Reply
    • Graeme Blake says Founder

      February 18, 2024 at 10:43 pm

      Practice matching up the terms in the answer to terms in the stimulus to see if it fits. Or try to think of an example of what each answer refers to. Do this as a review exercise. Use a dictionary to look up every word.

      And use simple examples. For example: “A phenomenon which is necessary for an outcome to occur but which is not sufficient.”

      “Playing with your dog is essential to keeping them happy.”

      Phenomenon: playing
      Necessary: playing
      outcome: dog happy

      You can describe simple ideas with abstract terms, and this helps you understand the abstract terms better.

      Note: This is an old comment but I wanted to clarify the point.

      Reply

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