LSAT Explanation PT 35, S4, Q23: The higher the altitude, the thinner

LSAT Question Stem

Which one of the following arguments is most similar in its reasoning to the argument above? 

Logical Reasoning Question Type

This is a Parallel question. 

Correct Answer

The correct answer to this question is D. 

LSAT Question Complete Explanation

This is a Parallel Reasoning question, which means we are looking for an answer choice that has a similar structure and reasoning to the given argument. The argument in the passage can be summarized as follows:

Premise: Higher altitude = thinner air

Premise: Mexico City has a higher altitude than Panama City

Conclusion: Therefore, Mexico City must have thinner air than Panama City

Let's analyze each answer choice:

a) As one gets older one gets wiser. Since Henrietta is older than her daughter, Henrietta must be wiser than her daughter.

This answer choice is not valid because the rule states that as one gets older, that same person gets wiser—not that you are wiser than anyone younger than you. The reasoning does not parallel the passage, so this choice is incorrect.

b) The more egg whites used and the longer they are beaten, the fluffier the meringue. Since Lydia used more egg whites in her meringue than Joseph used in his, Lydia's meringue must be fluffier than Joseph's.

The reasoning in this answer choice is flawed because the conclusion is based on limited information. Since beating is a requirement for fluffiness, there is no way to assess which cook has fluffier meringue without considering the beating factor. This choice does not parallel the passage's reasoning.

c) The people who run the fastest marathons these days are faster than the people who ran the fastest marathons ten years ago. Charles is a marathon runner. So Charles must run faster marathons these days than he did ten years ago.

This choice contains flawed argumentation, beginning with a general statement about the fastest runners of modern times versus those from a decade ago. We cannot draw a valid conclusion about any given individual without further information. This reasoning does not parallel the passage.

d) The older a tree, the more rings it has. The tree in Lou's yard is older than the tree in Theresa's yard. Therefore, the tree in Lou's yard must have more rings than does the tree in Theresa's yard.

This is the correct answer choice. Like the argument found in the passage, this one applies a basic general rule to draw a valid conclusion:

Premise: Older tree = more rings

Premise: Lou's tree is older than Theresa's tree

Conclusion: Therefore, Lou's tree must have more rings than Theresa's tree

e) The bigger the vocabulary a language has, the harder it is to learn. English is harder to learn than Italian. Therefore, English must have a bigger vocabulary than Italian.

This choice presents flawed conditional reasoning:

Premise: Bigger vocabulary = harder to learn

Flawed Conclusion: English is harder to learn, therefore it has a bigger vocabulary

The author here is guilty of the classic Mistaken Reversal, so this reasoning is flawed and cannot possibly parallel the valid argumentation found in the passage.

In summary, answer choice (D) is the correct choice because it parallels the reasoning found in the passage by applying a basic general rule to draw a valid conclusion.