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- Fri May 26, 2017 4:46 pm
#35407
Complete Question Explanation
Flaw in the Reasoning—CE. The correct answer choice is (E)
The conclusion of the argument suggests a causal relationship between fiber consumption and colon cancer:
Premise:
Studies show a negative correlation between high-fiber diets and the incidence of colon cancer.
Conclusion: Insufficient consumption of fiber causes colon cancer, and sufficient consumption of fiber prevents it.
While this is technically a Flaw in the Reasoning question, the question stem asks us to identify a possibility that shows why the argument’s reasoning is flawed. Arguments frequently fail to take into account any number of different possibilities, most of which entirely irrelevant to the logical validity of the conclusion. A discrete number of possibilities, however, would be relevant and should have been taken into account. Why? Because, if true, they could potentially weaken the argument. Remember: Only possibilities that could potentially weaken the argument are possibilities that the author should have considered, and whose omission amounts to a logical flaw! So, even though this is a Flaw question, the correct answer choice will state a possibility that, if true, weakens the conclusion of the argument.
Answer choice (A): It does not matter if the consumption of fiber in many countries is rising. Without additional information regarding the concurrent rise (or fall) in the incidence of colon cancer, we cannot determine the logical implication of this finding.
Answer choice (B): This Opposite answer describes a possibility that, if true, would only strengthen the conclusion that high-fiber diets reduce the risk of colon cancer.
Answer choice (C): Whether or not fiber is difficult to include in a regular diet would only be relevant if the author explicitly recommended the consumption of fiber-rich foods. No such recommendation was made, as the argument only seeks to establish a causal link between fiber and colon cancer.
Answer choice (D): This answer choice may seem attractive, because it attempts to invalidate the evidence used in support of the causal conclusion. There are several problems with this approach. First, attacking the factual premises of any argument is rarely helpful: your job is to undermine the causal relationship in the conclusion, not the correlation upon which that conclusion is based. Secondly, even if the cancer-fighting properties of fiber varied among different foods, it is still possible that fiber and colon cancer are causally related. After all, the rate of colon cancer is lower than expected in the non-Western countries where people eat fruits and vegetables, and also in the areas of Scandinavia where people eat cereals.
Answer choice (E): This is the correct answer choice, as the author should have controlled for factors suggesting an alternative cause for the correlation observed. If fiber-rich foods also contain other substances that tend to prevent colon cancer, then the negative correlation described in the stimulus can no longer be attributed to fiber alone. This would immediately undermine the causal assumptions upon which the conclusion depends, weakening the argument as a whole.
Flaw in the Reasoning—CE. The correct answer choice is (E)
The conclusion of the argument suggests a causal relationship between fiber consumption and colon cancer:
Premise:
Studies show a negative correlation between high-fiber diets and the incidence of colon cancer.Conclusion:
Insufficient consumption of fiber causes colon cancer, and sufficient consumption of fiber prevents it.- Cause Effect
Fiber 
Colon cancer
Fiber Colon cancer
While this is technically a Flaw in the Reasoning question, the question stem asks us to identify a possibility that shows why the argument’s reasoning is flawed. Arguments frequently fail to take into account any number of different possibilities, most of which entirely irrelevant to the logical validity of the conclusion. A discrete number of possibilities, however, would be relevant and should have been taken into account. Why? Because, if true, they could potentially weaken the argument. Remember: Only possibilities that could potentially weaken the argument are possibilities that the author should have considered, and whose omission amounts to a logical flaw! So, even though this is a Flaw question, the correct answer choice will state a possibility that, if true, weakens the conclusion of the argument.
Answer choice (A): It does not matter if the consumption of fiber in many countries is rising. Without additional information regarding the concurrent rise (or fall) in the incidence of colon cancer, we cannot determine the logical implication of this finding.
Answer choice (B): This Opposite answer describes a possibility that, if true, would only strengthen the conclusion that high-fiber diets reduce the risk of colon cancer.
Answer choice (C): Whether or not fiber is difficult to include in a regular diet would only be relevant if the author explicitly recommended the consumption of fiber-rich foods. No such recommendation was made, as the argument only seeks to establish a causal link between fiber and colon cancer.
Answer choice (D): This answer choice may seem attractive, because it attempts to invalidate the evidence used in support of the causal conclusion. There are several problems with this approach. First, attacking the factual premises of any argument is rarely helpful: your job is to undermine the causal relationship in the conclusion, not the correlation upon which that conclusion is based. Secondly, even if the cancer-fighting properties of fiber varied among different foods, it is still possible that fiber and colon cancer are causally related. After all, the rate of colon cancer is lower than expected in the non-Western countries where people eat fruits and vegetables, and also in the areas of Scandinavia where people eat cereals.
Answer choice (E): This is the correct answer choice, as the author should have controlled for factors suggesting an alternative cause for the correlation observed. If fiber-rich foods also contain other substances that tend to prevent colon cancer, then the negative correlation described in the stimulus can no longer be attributed to fiber alone. This would immediately undermine the causal assumptions upon which the conclusion depends, weakening the argument as a whole.