Assumption-SN. The correct answer choice is (C)
This stimulus mixes elements of causal and conditional reasoning, which is why it is important to have a solid understanding of both reasoning paradigms.
Whenever the author begins an argument by describing what “some people claim,” you can be almost certain that the main point of the argument will be a direct opposite of theirs. If “some people” believe that herbs are not prescribed because of their dubious medical effectiveness, the author will probably conclude that there is another explanation for it. The argument and counter-argument in this stimulus can be summarized as follows:
- Cause Effect
Some people: Effectiveness in doubt Physicians don’t prescribe herbs
Author: Herbs cannot be patented Herbs cannot be recommended
You should immediately notice that the alternative explanation provided by the author only explains why drugs cannot be sold, not why physicians don’t prescribe them. The second sentence of the stimulus establishes a conditional relationship between the sale of drugs and regulatory-agency approval, and the rest of the stimulus explains why regulatory-agency approval cannot be secured by herb manufacturers:
- Premise 1: Sells drugs RA approval
Premise 2: RA approval $200 million
Premise 3: $200 million Hold a Patent
Premise 4: Herb manuf. Hold a patent
The last premise triggers a contrapositive chain, which leads to the conclusion that manufacturers cannot expect to recover the $200 million in costs to get the regulatory-agency approval, and therefore cannot offer the drugs for sale:
- Herbs cannot be patented Herbs cannot be sold
The author’s conclusion, however, is slightly different. She argues that because herbs cannot be patented, physicians cannot recommend (or prescribe) their medicinal use:
- Herbs cannot be patented Herbs cannot be recommended
This conclusion is valid only if we assume that licensed physicians cannot recommend something that isn’t offered for sale:
- Herbs cannot be sold Herbs cannot be recommended
The logical opposite of this Supporter Assumption most certainly weakens the argument: what if herbs could still be recommended by licensed physicians even though they weren’t offered for sale (perhaps they are available for free)? Answer choice (C) is therefore correct.
Answer choice (A): Because the author presents an alternative explanation for the fact that herbs are not prescribed as drugs, it is not necessary that herbs are medically ineffective. This answer choice supports the counter-argument the author is attempting to discredit, and is therefore incorrect.
Answer choice (B): When a substance is properly used as a drug is outside the scope of this argument and not something the author relies on in making her conclusion. This answer choice is incorrect.
Answer choice (C): This is the correct answer choice. See discussion above.
Answer choice (D): Non-herb substances are irrelevant to this argument. The only possible effect this answer choice might have on the stimulus is to provide a third explanation as to why herbs are not available as drugs, by virtue of analogy: if herbs also treated conditions that are too uncommon to make the sale of herbs profitable, then no wonder herbs aren’t available as drugs. This proposition would weaken the established causal relationship between physicians and herbs and is therefore not a correct assumption.
Answer choice (E): The cost of medical care is irrelevant to this argument.
Remember: the answer to an Assumption question will be confined to the exact nature and scope of the argument without introducing new elements to it.