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#12 - The number of different synthetic chemical compounds

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Complete Question Explanation

Flaw in the Reasoning. The correct answer choice is (D)

The author begins this stimulus by pointing out that the number of synthetic carcinogenic chemical compounds, used as pesticides, preservatives, or food additives, is small in comparison to the number of non-synthetic carcinogenic compounds found in plants and animals. Based on this premise the author concludes that one cannot point to synthetic carcinogens as the cause of the increased cancer rates of the last few decades.

Since we are searching for a weakness in the argument, we should consider that a numbers comparison like the one offered might not be applicable to this inquiry—that is, even if there are many non-synthetic carcinogens in existence, we cannot draw conclusions about their practical effects on cancer rates without knowing how much cancer they cause. Instead of considering whether there are more natural or synthetic carcinogens, we should consider which type offers the greatest practical threat (which type leads to the greatest actual number of cancer cases, for example).

Answer choice (A): Pollutants are not the same as carcinogens. Furthermore, by offering an alternative cause this answer choice would actually strengthen the conclusion that the increased cancer rates are not attributable to synthetic carcinogens.

Answer choice (B): This does not weaken the conclusion regarding non-synthetic carcinogens and would, like answer choice (A), actually strengthen that conclusion.

Answer choice (C): Toxic is not synonymous with carcinogenic, so this answer choice would not weaken the argument in the stimulus in any way.

Answer choice (D): This is the correct answer choice. While there is a large number of non-synthetic carcinogens, exposure to these compounds is limited. On the other hand, there is increased exposure to synthetic carcinogens that is coincident to the increased cancer rate. As stated in the prephrased answer, it is the exposure to the carcinogens, not their numbers, which is responsible for the increased cancer rate.

Answer choice (E): Varied susceptibility is not overlooked; it is simply irrelevant to the argument in the stimulus, which concerns the possible causes of cancer rates that we know to have increased in recent decades.
DaleH
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Hi Powerscore staff!

I am a little bit confused about the classification of this question. Why is is that this question is considered a "flaw in the reasoning" type, whereas PrepTest 50, section 4, Question 17 is considered a "weaken " type. They both have very similar question stems ("... is most vulnerable to criticism on the grounds that it overlooks the possibility that").

Clarification on this would be greatly appreciated!

- Dale
Jonathan Evans
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Hi, Dale,

Great question, and you've come across a peculiarity in question classification. In general when a question is phrased...

    "The argument/reasoning above is most vulnerable to criticism on the grounds that it..."

...we would typically classify such a question as a Flaw question. However, there are some important nuances!

Let's consider three distinct possibilities:

  1. "The argument/reasoning above is most vulnerable to criticism on the grounds that it..." — this is a typical Flaw question.
    The credited response will include a description of the most salient flaw in the reasoning.
  2. "The argument/reasoning above is most vulnerable to criticism on the grounds that it overlooks the possibility that..." — this is a Flaw question for which the credited response will be a statement that weakens/hurts the conclusion.
  3. "The argument/reasoning above is most vulnerable to criticism on the grounds that it presumes without providing justification..." — this is a Flaw question for which the credited response will be a tacit assumption in the author's reasoning.

In other words, depending how a Flaw question is presented, the credited response could be in the form of a (1) description of the flaw, (2) a statement that hurts the argument, or (3) an assumption present in the argument.

Sometimes you will come across Flaw question that includes two or all three possibilities in answer choices. For example, consider PrepTest 39, Section 4, Question 20.

This question has the conventional Flaw question stem:

    The reasoning in the argument is most vulnerable to criticism on the grounds that the argument

However, two answer choices begin "presumes, without providing justification;" two begin "overlooks the possibility that;" and one begins "does not acknowledge that." This last phrase would also introduce a "weaken" scenario.

Thus, classification of these questions becomes somewhat facultative. Both the questions you cited can be understood as Flaw questions or as Weaken questions. However, given this distinct Flaw-style language, I would approach any such question by default as a Flaw question. Identify the flaw in the reasoning first, then pay attention to the particular syntax of the question and the answer choices.

I hope this helps!