PrepTest 144

[lcid:3672] Prep Test 144 LSAT — Reading Comp — S1 Reading comp

Passage

 . Passage A  .       Karl Popper's main contribution to the philosophy  . of science concerns the power of negative evidence. Remaining source text redacted.
Passage walkthrough
Passage SummaryTopic: Science

Passage A
Paragraph 1
  • Paragraph note
    • A philosopher is introduced, and his theory is explained in depth, focusing on a distinction
  • Views, minor Meta-Structures, points of intersection, and the author's attitude
    • Popper - Theory of negative evidence (vs positive evidence)
    • Example - "All swans are white"
      • Positive evidence - white swans (can't prove all are white); Popper says no value
      • Negative evidence - black swan (one proves idea is wrong); Popper says disproves
    • Author - Popper's view "hyperbolic"
    • Popper - Negative evidence is core of science (scientific theory → makes predictions testable with negative evidence)
Paragraph 2
  • Paragraph note
    • The Author rebuts Popper's argument to some degree
  • Views, minor Meta-Structures, points of intersection, and the author's attitude
    • Author - Popper's view doesn't reflect scientific reality
    • False prediction, premise of theory is wrong
    • But which one? All theories have "auxiliary" premises from other theories and the real world (e.g., instruments work)
    • Author - Popper is right to say positive evidence isn't conclusive; wrong to say negative evidence is
Passage B
Paragraph 1
  • Paragraph note
    • A scientific situation is walked through
  • Views, minor Meta-Structures, points of intersection, and the author's attitude
    • Uranus orbit predictions were off, relied on Newton's laws, and auxiliary assumptions (including no other planets were nearby)
    • Predictions wrong, so a premise must have been wrong
    • Scientists tested other planets around, found that was the mistake
Paragraph 2
  • Paragraph note
    • A similar scientific situation is walked through
  • Views, minor Meta-Structures, points of intersection, and the author's attitude
    • Mercury orbit predictions were off, scientists predicted another planet (like with Uranus)
    • No planet found, Einstein's new laws matched up with reality, so scientists rejected Newton's theory
Main Point:
Passage A - Popper's philosophy of science doesn't reflect the reality scientists face, especially with respect to the certainty with which negative evidence can disprove theories.

Passage B - When predicting the orbit of Uranus, scientists were correct in predicting a new planet, but in a similar situation with Mercury, it was actually Newton's laws that were shown to be incorrect.

Key Lines:

Passage A:
Lines 3-5 - An example makes a distinction much clearer
Lines 6-10 - A view is clarified and the Author calls it exaggerated ("hyperbolic")
Lines 17-19 - The Author criticizes the opposing view
Lines 30-32 - The Author clarifies her view, showing a shared viewpoint and an opposed viewpoint with the opposing point

Passage B:
Lines 41-44 - Alternative possibilities are discussed
Lines 48-51 - One possibility is shown to be correct
Lines 53-54 - A similar situation is raised
Lines 58-64 - A different possibility is shown to be correct in this example, with implications for the first

Meta-Structure - Relationship Between Passages:
Rebuttal (Passage A) - The Author of Passage A clearly thinks that Popper's philosophical contribution isn't 100% correct. However, she does clarify this at the end. Popper claims that positive evidence is inconclusive, but negative evidence is definitive in disproving a claim. The Author agrees that positive evidence is inconclusive (though she disagrees with Popper's view that it lacks all value), but she disagrees that negative evidence is always conclusive.

Comparisons (Passage B) - Passage B brings up two similar situations—planets are discovered, their orbits are predicted, and those predictions are wrong. However, the outcome of these situations is different. In the Uranus situation, it ended up being an auxiliary assumption (no other planets in the area) that was wrong. In the Mercury situation, it ended up being Newton's theories that were wrong.

Neutral Author (Passage B) - The Author of Passage B doesn't really take any sides or show any opinion. Rather, he focuses on presenting the details of two separate situations.

How do these passages relate? In a complicated manner! The first passage discusses an approach to scientific inquiry that revolves around positive and negative evidence. How does this apply to the two situations in Passage B? Well, in the Uranus case, the scientists used what they knew to predict an orbit, and that orbit turned out to be wrong. In other words, they made a prediction, and the evidence proved that prediction wrong—negative evidence!

In the Mercury example, they predicted an orbit that turned out to be wrong, so that's more negative evidence. They also then made a prediction that, similar to the Uranus situation, there would be another planet, but they didn't find one—also negative evidence!

(This was a lot of analysis, and we almost certainly wouldn't have walked through all of this ahead of heading to the questions. It's here to help you wrap your head around the passages!)

Also important to note is that the Author of Passage A talks about "auxiliary" assumptions, and Passage B brings these up as a possible place for a prediction made by a theory to go wrong. That overlap aligns the approach in Passage B with that of the Author over Popper.

Last Thoughts:
This comparative set is rough. It's hard to understand, abstract, and definitely outside of most people's area of expertise. So what can you do to make it easier? Rely on that example in Passage A, Paragraph 1. If we can understand what positive and negative evidence is, we should be able to muddle through the detail questions. And as for the Authors' viewpoints, Passage A has some clear statements of opinion, and Passage B lacks a particularly present author.

Question prompt

In passage B, which Remaining source text redacted.
Why the credited answer is right

Credited answer: C

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

Question Type

Science

Answer choices

  1. A
    Uranus
    Why choice A is not credited
    Incorrect. Uranus didn't disturb its own orbit, throwing predictions off.
  2. B
    the sun
    Why choice B is not credited
    Incorrect. (Lines 34-37) The mass of the sun, while based on an assumption, was a known force, so the scientists weren't assuming that it was absent. It was a known force, so it didn't disturb their calculations.
  3. C
    Neptune
    Why choice C matches the stem
    Correct. Question Type:
    Parallel Reasoning

    Strategy Overview:
    Review the relevant section in Passage A to clearly define "disturbing force" and then consider the situations in Passage B to find something that serves as an example of it

    Answer Anticipation/Relevant Lines:
    Let's head back to Line 26 to see what these disturbing forces are! Checking there, we can see that the relevant sentence starts in Line 22. It's talking about taking a theory and making predictions from it, but the Author points out that doing so requires "auxiliary" premises. So these premises must be other things they're working from or assuming are true in order to make the prediction.

    It gives us a list of where these premises come from—other theories, instruments working, and, most relevantly, the "absence of disturbing forces." So when a scientist is taking her theory and making a prediction, she assumes that there aren't any relevant forces that could throw her predictions off that she doesn't know about. And since it's asking us for an example of a disturbing force, we're looking for a relevant force that threw predictions off but that the scientists weren't aware of.

    So what threw off predictions in Passage B? Neptune! When predicting the orbit of Uranus, the scientists took what they knew about Newton's theories and the planets and suns that they were aware of and made a prediction assuming that there were no other forces that would influence the orbit. However, there was a disturbing force that threw off their calculations—Neptune. Let's find that as an answer.

    Answer Explanation:
    (Lines 37-39) When predicting Uranus's orbit, scientists assumed that there were no other planets in the area. If there were, then that planet would be an unaccounted-for force that would throw off their predictions—a disturbing force. And there was such a planet in the vicinity of Uranus—Neptune. This answer is therefore correct.

    Key Takeaway:
    We want to focus on answers (A) and (D) here. In a question like this, you take all the help you can get! And if two answers are functionally equivalent, they can't both be right, so they must both be wrong.
  4. D
    Mercury
    Why choice D is not credited
    Incorrect. Similar to (A), Mercury was the focus of the prediction, not a disturbing force that could influence its orbit as predicted. You could also have eliminated this answer (and (A) with it) because Mercury and Uranus serve the same function in the two different situations, and so they can't both be correct!
  5. E
    the moon
    Why choice E is not credited
    Incorrect. The moon isn't mentioned in Passage B!

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