#7 - Antibiotics are standard ingredients in animal feed

[Administrator]

Complete Question Explanation

Must Be True—SN. The correct answer choice is (E)

This stimulus contains a set of facts, without a conclusion. Interestingly, both causal reasoning and conditional reasoning are at play here.

The facts tell us that although antibiotics are standard ingredients in animal feed that keep animals healthy and increase meat yields. This is a causal relationship:

A = antibiotics
HA = healthy animals
IMY = increased meat yields

• Cause Effect
  HA
  A +
  IMY

However, scientists have recommended phasing out antibiotics due to fear their use may make antibiotics less effective in humans. We are warned that some farmers will go out of business if meat yields are reduced, which expresses a conditional relationship:

IMY= meat yields not increased, meaning they are reduced from the prior levels caused by antibiotics
FOB = some farmers will go out of businesses

• Sufficient Necessary
  
  IMY FOB

Not surprisingly, given the stimulus is a fact set, this is a Must Be True question. Since the use of antibiotics in animal feed increases meat yields, then if the scientists’ recommendation is implemented, the cause of increased yields will be gone, and the meat yields will be reduced. We know that if meat yields are reduced, some farmers will go out of business. So, we can infer that if the scientists’ recommendation is implemented, some farmers will go out of business. While it is not necessary to diagram this chain of reasoning, it can be diagrammed as:

SRI = scientists’ recommendation implemented

• Sufficient Necessary/Sufficient Necessary
  
  SRI IMY FOB

Answer choice (A): Whether the scientists are right or wrong about the decreased effectiveness of antibiotics in humans, the implementation of their recommendation requires that some farmers go out of business.

Answer choice (B): This answer choice is incorrect, because it says the antibiotics will become ineffective in humans, while the stimulus only contained the theory that the antibiotics could become less effective.

Answer choice (C): Here, the sufficient condition is that the recommendation is not heeded, but the stimulus does not tell us about what will happen in that event. We only know what will occur if the recommendation is heeded. This answer choice is a Mistaken Negation of the information in the stimulus.

Answer choice (D): The stimulus only discussed the business impact on farmers of reduced meat yield on farmers, and not reduced animal health. This answer choice presents new information not supported by the stimulus.

Answer choice (E): This is the correct answer choice, because it expresses our prephrase, that some farmers will go out of business due to reduced meat yields if the use of antibiotics in the feed is phased out. Do not be thrown off by the inclusion of the “unless” clause. It is consistent with the stimulus to say that if there were some other means of increasing meat yields, then that could prevent the farmers from going out of business because of a reduction in meat yields resulting from the phase out.

[grunerlokka]

Thanks for the above explanation. I am however having trouble understanding the reasoning behind the following part of the explanation:
"We are warned that some farmers will go out of business if meat yields are reduced, which expresses a conditional relationship:
IMY= meat yields not increased, meaning they are reduced from the prior levels caused by antibiotics
FOB = some farmers will go out of businesses"

The stimulus specifically says "If meat yields are reduced", some farmers will go out of business".
So my conditional statement for this was: MYR (meat yields reduced) some farmers go out of business.
The contrapositive: some farmers do not go out of business MYNR (meat yields not reduced)

In other words, in my conception (and based on the chapter on this in the powerscore) the logical opposite for "reduced" is "not reduced" (not "increased"). "Not reduced" can mean that yields stay the same or possibly increase.

That's why your explanation and answer (E) is confusing. E says some farmers will go out of business "unless they use other means of increasing meat yields", as if an increase is the only way to stay in business. Is there not, for example, the possibility of staying in business by simply keeping meat yields constant (i.e which also counts as "not reducing")?

[Paul Marsh]

Hi grunerlokka! Great question, and nice application of logical opposites.

You are quite correct that the logical opposite of "reduced" is "not reduced" (as opposed to "increased"). The conditional should indeed be written:
meat yields reduced some farmers going out of business

However, our stimulus does not use conditional reasoning all the way through; trying to treat this stimulus as a conditional chain would potentially be misleading.

Our first sentence of the stimulus tells us that antibiotics are currently standard practice, and that they currently are causing increased meat yields. In other words, meat yields have already been increased by the standard practice of antibiotics in animal food. This suggests that a reduction in antibiotics in animal food would lead to some reduction in meat yields (a return to how it was before the increased meat fields). So no, the way the first sentence is phrased doesn't really leave open the possibility of a reduction of antibiotics in animal food leaving meat yields constant, because the thing causing the current high level of meat yields would disappear. So meat yields would be reduced, which sets off our conditional resulting in some farmers going out of business.

So I can see how the language here could be a bit confusing, but if you just think about the first sentence of the stimulus in a practical sense then it sure seems like it's implying that a reduction in antibiotics would also reduce meat yields. Again, you did a nice job of correctly applying logical opposites, but I think this is an example of a question where trying to shoehorn everything into conditional format can potentially mess you up.

Hope that helps!