Logical reasoning PrepTest 125 · Section 4 · Question 19

Incorrect. The argument discusses only that these features are typically present in TdF winners; it makes no claims as to the causality of them leading to the wins.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
TdF winner → Abnormal physiology
This abnormal physiology is typically exceptional lung capacity and exceptional heart power
Last year's winner: not Exceptional heart power
Conclusion - Last year's winner: Exceptional lung capacity

Answer Anticipation:
First, looking at the question stem, it adds in a bit more info than we normally see in an Errors in Reasoning question stem—it specifically tells us to find an answer that highlights a possibility overlooked by the argument. We should keep that in mind as we anticipate an answer.

Now, moving to the argument and the flaw itself, we should start with the conclusion. That conclusion is that last year's TdF winner must have exceptional lung capacity. Why? Because it rules out another abnormal physiological feature that he might have had. When an argument reaches a conclusion by ruling out a separate possibility, it's using a common method of reasoning—eliminating alternatives.

In order to do so validly, the argument needs to establish that the list of possibilities is complete, and then effectively rule out every possibility except one. Here, the latter is more or less done (maybe the tests didn't detect such a heart, but that seems unlikely), but the former isn't.

While it is established that all TdF winners have had abnormal physiological constitutions, the lung capacity and heart power are listed as physiological features that are "typical" of these abnormalities. While that does establish they're the most prevalent features, it doesn't establish that they're the only ones. So the argument is ignoring the possibility that there could be another abnormal physiological feature present in last year's winner, not big lungs or a powerful heart.

Answer Explanation:
This answer highlights the error in reasoning from the argument—it establishes only that these two abnormal physiological features are "[t]ypical" of TdF winners, not that they're the only two features present or that they're present in all TdF winners. While last year's winner must have at least one abnormal physiological feature, it could be something other than the two listed in the stimulus.

Key Takeaway:
Arguments that reach a conclusion that "picks" one option after eliminating others are using a common method of reasoning—eliminating alternative options. To validly use this method, the argument must establish the list of options under consideration is complete, and then it must effectively rule out all but one option. When an argument using this method of reasoning is flawed, it's likely missing one of these pieces, and identifying what is missing will lead you to the answer.

Incorrect. This answer is a bit of a partial negation/reversal of the relationship that the argument is assuming. There, the winner lacking a powerful heart is used to conclude that he has exceptional lung capacity. This answer says that someone who lacks that lung capacity probably won't have a powerful heart.

Incorrect. How the winners got the abnormal physiological features is out of scope of the argument about which ones are present in a specific athlete.

Incorrect. These features would still be abnormal, and the determination made about last year's winner is using this criteria, so it's not something the argument overlooks.