Logical reasoning PrepTest 126 · Section 1 · Question 24

Incorrect. While this answer might highlight that one way someone could end up losing weight from a high-protein diet doesn't apply (it doesn't make one feel full), that doesn't preclude it from resulting in weight loss through some other mechanism, so this possibility isn't something the argument overlooks.

Incorrect. This answer tries to serve as a counterexample, but it fails. The conclusion is that following the diet will result in weight loss. Showing that people who don't follow the diet can lose weight isn't a counterexample; showing people who do follow the diet and don't lose weight is. As such, this answer is incorrect.

Incorrect. If the group who exercised more completely (or mostly) overlapped with the group that followed the high protein/breakfast diet, then this answer might raise an alternative cause and thus serve as something the argument overlooked. However, it's possible that the diet in question helped with weight loss, and so did the exercise—and those who followed both lost the most weight. That would be consistent with the details in the argument.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
Study - Those who lost the most weight followed a high-protein/big breakfast diet.
Ad - Anyone who follows our high-protein/big breakfast diet will definitely lose weight.

Answer Anticipation:
The conclusion here is based on a study, so we should start by considering the two most common flaws associated with studies—sampling, and correlation/causation.

For the sampling flaw, there's no specific indication that the study was done on an unrepresentative sample, or a sample that was too small. It also appears as if everyone was studied generally—no one was given a specific diet, the scientists just looked at the diets of those who lost the most weight. As such, it's possible that the answer could bring up a piece of information not in the stimulus that would make a sampling flaw answer correct, but it's unlikely since there's no provided information suggesting it.

For the correlation/causation flaw, the argument assumes causality here, based on a correlation between diet and weight loss in the study. That's a common pattern, and it tells us that we should be looking for an answer highlighting that shift.

However, there's an important note here that we should be generally aware of any time we're dealing with correlation/causation flaws. Here, the correlation and causal statements are absolute. They don't state that one group was "more likely" than another to see the effect; they state that those who lost the most weight followed a specific diet. The conclusion doesn't state that following the diet will increase the chances of losing weight; it states that anyone following it will surely lose weight. This is stronger than the usual correlation/causation language.

Why is this relevant? Well, normally, a few outliers won't hurt a correlation/causation argument. Sure, some smokers don't get lung cancer, but the overall risk is higher among the smoker population, so the causal relationship between smoking and lung cancer holds. Here, since the relationships in the stimulus are so strong, a single counterexample—someone who follows the diet and doesn't lose weight—is enough to call the conclusion into question. Whereas we'd normally eliminate an answer that discusses "some" people who followed the diet and didn't lose weight, here that answer would be correct.

Answer Explanation:
This answer does present counterexamples that completely undermine the argument. It directly raises a group that has the supposed cause (the diet) but lacks the effect (weight loss), and that's sufficient to invalidate the conclusion because of its strength— "anyone" who follows the diet will lose weight. If even one person doesn't lose weight while following the diet, then that claim is wrong.

Key Takeaway:
In a normal correlation/causation argument, the relationship between cause and effect isn't 1:1 and so weak counterexamples can be chalked up as outliers and thus dismissed as not impacting the argument. However, when the relationship in the conclusion is absolute—anyone with the cause will see the effect—even a single outlier will be relevant in disproving it.

Incorrect. This aligns with the argument in that it explains why those who don't follow the diet might not lose weight, so it's not something the argument overlooks.