LSAT Explanation PT 34, S2, Q17: Dietary researcher: A recent study reports
LSAT Question Stem
Which one of the following, if true, would most weaken the dietary researcher's argument?
Logical Reasoning Question Type
This is a Weaken question.
Correct Answer
The correct answer to this question is A.
LSAT Question Complete Explanation
This LSAT problem presents an argument from a dietary researcher who is skeptical about the recent study that suggests reduced-calorie diets can extend North Americans' life spans. The researcher argues that laboratory animals in the study eat more than animals in their natural habitats, which shortens their life expectancy. Restricting their diets merely brings their caloric intake back to natural, optimal levels and reinstates their normal life spans. Therefore, the researcher concludes that the study does not support the idea that reduced-calorie diets can extend North Americans' life spans.
The structure of the argument is as follows:
Premise: Laboratory animals eat more than animals in their natural habitats, shortening their life expectancy.
Premise: Restricting laboratory animals' diets brings their caloric intake back to natural, optimal levels and reinstates their normal life spans.
Conclusion: The study does not support the idea that reduced-calorie diets can extend North Americans' life spans.
An "Evaluate" question for this argument could be: "Do North Americans typically consume a higher number of calories than the optimal number of calories for a human diet?"
The question type of this problem is Weaken, which asks us to identify the answer choice that would most weaken the dietary researcher's argument.
Answer choice A is the correct answer. If North Americans, on average, consume a higher number of calories than the optimal number of calories for a human diet, it would suggest that they are similar to the laboratory animals in the study. This would weaken the researcher's argument that the study does not support the idea that reduced-calorie diets can extend North Americans' life spans, as reducing their caloric intake might bring them back to natural, optimal levels and extend their life spans.
Answer choice B is incorrect because it compares two groups of North Americans who both have low-calorie diets, focusing on the fat content rather than the total caloric intake. This does not address the researcher's argument.
Answer choice C is incorrect because it is too vague and does not address the specific study in question. The fact that not all scientific results with important implications for human health are based on studies of laboratory animals does not weaken the researcher's argument.
Answer choice D is incorrect because it only states that some North Americans who follow reduced-calorie diets are long-lived, without comparing them to North Americans who do not follow reduced-calorie diets. This does not provide enough information to weaken the researcher's argument.
Answer choice E is incorrect because it is too vague and does not specifically address the relationship between diet and longevity in humans or the laboratory animals in the study. The strong correlation between diet and longevity in some species of animals does not weaken the researcher's argument.