Logical reasoning PrepTest 113 · Section 3 · Question 14

Question prompt

Historian: Leibniz, the seventeenth–century Remaining source text redacted.
Why the credited answer is right

Credited answer: E

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

Argument or Facts

Argument

Valid or Flawed

Flawed

Question Type

Strengthen with Necessary Premise Questions

Stimulus Summary

Question - Who discovered calculus?
Answer 1 - Leibniz, because he published first
Answer 2 - Newton, because his notebooks show he used it before Leibniz’s publication, and he sent Leibniz a letter about it (but people say the letter didn’t actually have the relevant info
Historians answer - They both independently discovered calculus

Answer Anticipation

The stimulus is set up to answer a question about the discoverer of calculus. Two answers are proposed, with some historical information about both of them. From that, the author concludes that the two independently discovered calculus.
In order to prove that, the author would have to show three things. First, Leibniz didn’t steal from Newton. Second, Newton didn’t steal from Leibniz. Third, neither stole from someone else.
Does it show Leibniz didn’t steal from Newton? If he did, he would have had to either have seen Newton’s private notebooks, divined it from the letters that were “cryptic,” or had some other interaction with Newton. So an answer that rules out these possibilities could be correct.
Does it show that Newton didn’t steal from Leibniz? More or less, yes. If Leibniz didn’t publish until a decade after Newton started using calculus, it’d be hard for the latter to steal from the former. An answer ruling out some way that Newton could have learned from Leibniz a decade ahead of the latter’s publication would serve as a necessary assumption, but that seems unlikely.
Does it show that neither stole ideas from a third party? It doesn’t address this possibility at all - and so the correct answer is likely to rule it out, or provide necessary evidence to do so.

Answer choices

  1. A
    Leibniz did not tell Remaining source text redacted.
    Why choice A is not credited
    If Leibniz told people who had no idea what he was talking about, or people that didn’t tell anyone else, then these other people couldn’t have then told Newton of the discovery. As such, it’s not necessary that Leibniz remained completely tight-lipped about calculus ahead of publication - just that no one he told then told Newton (or told someone who told someone who…).
  2. B
    No third person independently Remaining source text redacted.
    Why choice B is not credited
    If it’s possible for two people to independently discover calculus, then it’s possible for three people to do so! The argument assumes no third person discovered calculus first and then their discovery was conveyed to Leibniz or Newton, but someone else could have discovered it and not passed it on to either two, allowing them to independently discover it.
  3. C
    Newton believed that Leibniz Remaining source text redacted.
    Why choice C is not credited
    What matters for discovery is if someone actually learned something important from another, not whether that second person believed they did. If Newton thinks his cryptic message conveyed the ideas of calculus, but Leibniz thought he was just being a weirdo (look him up, Newton was a weird guy), then Leibniz could still have independently discovered calculus.
  4. D
    Neither Newton or Leibniz Remaining source text redacted.
    Why choice D is not credited
    What matters is if one knew the other had developed calculus before they discovered calculus. If Leibniz independently discovered calculus, but then found out Newton had, as well, between the discovery and his book’s publication, then the argument could still hold.
  5. E
    Neither Newton nor Leibniz Remaining source text redacted.
    Why choice E matches the stem
    This answer rules out the possibility that one of the two individuals in the stimulus actually learned of calculus from someone else. If that’s the case, then it calls into question whether that person independently discovered calculus - not because they learned it from the other, but because they learned it from somewhere else.

What this tests

Question analytics

Based on historical answer selection rates for this question.

Answer choice distribution

  1. A 3%
  2. B 12%
  3. C 5%
  4. D 14%
  5. E Credited 66%

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