MCAT Critical Analysis and Reasoning Skills Question 16: Answer and Explanation

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Question: 16

5. Which of the following, if true, would most UNDERMINE Hume's conclusions about cause and effect?

  • A. There is no reason to believe that the laws of nature will change tomorrow.
  • B. Some knowledge is attainable completely independent of experience.
  • C. Most students of science fully appreciate the difference between correlation and causation.
  • D. Claims about causal relations can always be doubted.

Correct Answer: B

Explanation:

For (A), "There is no reason to believe that the laws of nature will change tomorrow," the relevant text is in P4, at the end of an analysis of a direct quote from Hume, the rhetorical question, "How do we know the laws of nature won't change tomorrow?" As a rhetorical question, it has one answer the author immediately expects readers to jump to: "We don't know." In short, this rhetorical question amounts to the claim that it's not possible to know whether the laws of nature will remain the same in the future.

Even if it were true that there is no reason at all to expect those laws to change tomorrow, the absence of evidence is not equivalent to the evidence of absence. In other words, just because there is no reason to believe that some event will happen does not by itself give an affirmative reason to believe that it won't happen. What this means is that the truth of (A) does not significantly challenge the truth of the statement that the laws of nature will change tomorrow—yet the actual assertion attributed by the author to Hume is not that this will definitely happen, but only that it's not possible to know, one way or another, whether it will. Choice (A) certainly does not undermine that idea, since it also amounts to a claim of ignorance.

Choice (B) directly pertains to the discussion at the start of P2:

"Hume's analysis begins from a simple principle, 'that all our ideas are copy'd from our impressions,' by which he means that all knowledge ultimately derives from sense experience—an axiom he shares with fellow empiricists Locke and Berkeley."

The language of begins, simple principle, and axiom (another name for a foundational assumption) all indicate that this is a claim that Hume takes for granted, while the colorful quotation shows that it's an acknowledged assumption, one that Hume deliberately calls attention to. As an axiom, it serves as a necessary condition for the conclusions that Hume reaches. Thus, if it's not true that "all knowledge ultimately derives from sense experience," then Hume's argument is in considerable trouble.

Given that (B) states that "Some knowledge is attainable completely independent of experience," it poses a direct contradiction to Hume's foundational principle. It would be difficult to offer a more substantial challenge than attacking a grounding assumption, so this is almost certainly the correct choice. If running low on time on Test Day, select this and move on. If timing is not an issue, it would be fine to continue checking the other choices to ensure that this one has the most negative impact.

Although (C), "Most students of science fully appreciate the difference between correlation and causation," directly conflicts with the opening sentence, "Every student of the sciences is taught to be wary of mistaking correlation for causation, but few fully appreciate the difference," this claim constitutes the author's lead-in to the discussion of Hume. It undermines the author's framing of the issue, but it is not relevant to any idea tied to Hume himself.

As expected, choice (D) also fails to have a negative impact. In fact, the statement "Claims about causal relations can always be doubted," is completely consistent with the author's concluding thought in P5, that "all inductive reasoning . . . is ultimately uncertain." Since it supports the author, and the author is never critical of Hume, there is no way this choice could undermine Hume.

After checking the other answers, it's clear that only choice (B) had a significantly negative impact on anything that can be connected immediately to Hume. In fact, its impact was so detrimental (analogous to demolishing a house's foundation) that such an answer can safely be taken as correct without consulting the remaining options.

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