Logical reasoning PrepTest 112 · Section 3 · Question 26

Question prompt

Before 1986 physicists believed Remaining source text redacted.
Why the credited answer is right

Credited answer: B

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 Questions

Stimulus Summary

Pre-1986 - Physicists believed the universe could be explained with 4 forces
Experiments/Phenomenon - A smaller measurement in gravitational attraction than predicted was found
New theory/Explanation - There’s a fifth force (repulsion between particles)

Answer Anticipation

Don’t try to understand particle physics in the time you have to answer this question! The correct answer isn’t going to deal with the content here, but rather the reasoning.
In this argument, an old theory and a new theory are presented, with experimental results leading to the adoption of the new theory. There are two important considerations here: How do the theories relate? And how do the experiments lead to the new theory?
For the first question, the new theory expands the old one. The new theory doesn’t question the four other forces from the old theory, it just adds a new one. It’s uncertain how this could lead to an answer, but it’s something we should always consider when there’s a new theory being brought up.
For the second question, the experiments based on the old theory predicted something that didn’t pan out. The new theory “would explain” these results. It’s important that the argument establishes as a fact that the new theory does, in fact, explain these results, as we therefore can’t strengthen the argument by establishing that this is true.
So how can we strengthen the argument? Well, as with many science-based questions, this one concludes an explanation for an observed phenomenon - the fifth force. It’s already been established that this theory does account for the phenomenon, so we can strengthen it by ruling out other potential explanations for it.
Let’s head into the answers expecting it to eliminate an alternative explanation while staying flexible in case it strengthens the argument by dealing with the large overlap between the theories.

Answer choices

  1. A
    The extremely sophisticated equipment Remaining source text redacted.
    Why choice A is not credited
    While this answer explains why the physicists didn’t have the results necessary to question the old theory, it doesn’t strengthen the specific new theory that there’s a fifth force. It’s just as likely that the new equipment is picking up a phenomenon caused by something else.
  2. B
    No previously established scientific Remaining source text redacted.
    Why choice B matches the stem
    This answer does strengthen the argument directly, and it’s a bit related to the overlap between the theories. The old theory stated that the universe could be explained using 4 forces. However, this answer establishes that it wasn’t based on evidence that there were only four forces - rather, the evidence was compatible with the idea of the fifth force, it just appears there was no evidence for one. With the new experiments, however, there is. This answer strengthens the argument by showing that all the previous evidence aligns with the new theory instead of contradicting it.
  3. C
    Some scientists have suggested Remaining source text redacted.
    Why choice C is not credited
    What some scientists have “suggested” doesn’t determine reality. Also, even if we accept what they say as true, this would suggest the “alleged” fifth force is actually an aspect of an existing force, thus weakening the argument.
  4. D
    The experiments were conducted Remaining source text redacted.
    Why choice D is not credited
    By calling the precision of the experiments that led to the new theory into question, this answer weakens the argument.
  5. E
    The fifth universal force Remaining source text redacted.
    Why choice E is not credited
    There being other exciting developments in a field doesn’t lend strength to any of them being correct.

What this tests

Question analytics

Based on historical answer selection rates for this question.

Answer choice distribution

  1. A 15%
  2. B Credited 64%
  3. C 5%
  4. D 11%
  5. E 5%

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