Logical Reasoning

PT140 · S1 · Q13 Animal feed should not include

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Animal feed should not include genetically modified plants.

Conclusion

Animal feed shouldn't include any GMO plants.

Evidence

In a study, rats that were fed GMO potatoes for 30 days tended to develop intestinal deformities and a weakened immune system, whereas rats fed a normal diet of non-GMO food didn't have these problem.

Evaluate

Since the author is making a cause/effect assumption about something that went down with a study, we can use our Curious Fact / Explanation mindset.

Curious Fact How come the rats fed GMO potatoes ended up with intestinal deformities and a bad immune system, whereas rats fet a non-GMO diet didn't have those problems?

Author's Explanation The GMO potatoes caused the gut and immune system problems.

We always affect these arguments in one of two ways: - Alternate Explanations for the curious fact or - Plausibility of the Author's Explanation

What else could explain why the GMO potato group ended up with gut / immune problems? Well ... potentially anything. Were we ever told that the two groups were otherwise fair to compare? Were they kept in the same environment? Were they allowed to sleep the same amount? Were they given similar exercise? Were there any other potentially funky parts of the GMO potato rats' diet?

Since the argument failed to establish that the only difference between these two groups was GMO potatoes vs. non-GMO potatoes, there is a whole world of potential alternate causes for why those rats got gut / immune problems (that would have nothing to do with the GMO-aspect of the potatoes they ate).

Goal

Since this is Weaken, we would want a correct answer to suggests a different explanation for why the rats in the GMO potato group ended up with gut / immune problems, or we would want a correct answer to say something that undermines the plausibility that GMO potatoes were really to blame.

Or, we would like any answer that goes against the conclusion and gives us a way to argue that animal feed should have GMO plants in it.

13.

Which one of the following, if true, most weakens the argument?

  1. Correct

    Potatoes are not normally a

    Why this is right

    This answer suggests an Alternate Explanation for why the rats in the GMO potato group got gut / immune problems: it wasn't the fact that the potatoes were GMO; it was just the fact they were potatoes. In order for this answer to make sense, we have to assume that the other group was not fed potatoes (of the non-GMO kind, since they got all non-GMO food). Are we allowed to assume that? Yes, it turns out, if we hunt for details. The non-GMO group was fed "a normal diet of foods that had no GMO". At first I just interpreted that "normal" to mean "you know, no GMO in it!". But it looks like LSAT is using that qualifier to pair up with the word "normally" in this answer choice, in order to silently establish that the untroubled group of rats was not fed potatoes of any kind. This type of Alternate Explanation is particularly sneaky, because if we got too loose with our understanding of the Author's Story, we might just think, 'He's saying the potatoes did it.' And this answer, as an Alternate Explanation, is also saying "the potatoes did it". But it's still a distinct explanation. The author thinks the potatoes were a problem because they had GMO ingredients, whereas this answer is suggesting the potatoes would be a problem whether they were GMO or not.

    Skill tested: Weaken · how this choice captures the argument's function is the move to repeat next time.

    62% picked this

  2. The rats tended to eat

    No Impact

    This answer doesn't quite add or subtract plausibility to the GMO-potato hypothesis. Since we know the GMO potato-eaters ended up with gut problems, it makes sense that they would be eating less of everything as the study went on. The fact that their potato appetite tapered off doesn't really lean towards any common sense explanation: was it because they had a sick stomach and were eating less? did they just get sick of potatoes? did the GMO aspects of the potatoes have anything to do with it? We just don't know.

    2% picked this

  3. Intestinal deformities at birth are

    No Impact: deformities at birth

    The only deformities being discussed in this paragraph developed over the course of the study, so deformities at birth are not relevant to this conversation.

    15% picked this

  4. Genetically modified potatoes have the

    No Impact: same nutritional value

    If it said that GMO potatoes had "way more" nutritional value, then maybe we could say that this answer weakens by saying, "we should use GMO plants in animal feed, since GMO plants sometimes have way more nutritional value than their non-GMO counterpart." But saying they are equally nutritious doesn't move this argument in any direction.

    8% picked this

  5. The researchers conducting the study

    Too Weak

    This answer potentially undermines the author's causal assumption (that the GMO aspect of the potatoes caused the gut / immune problems), by saying that we're not familiar with any causal mechanism that would allow GMO to impact gut / immune system. However, this is a pretty weak answer since it's just saying "the researchers conducting the study were unable to explain it". To have more punch, we'd want to know that the scientific community at large doesn't really have a theory for how GMO would impact gut / immune. We don't get that much of an objection by saying these researchers didn't know how. We don't even know if GMO was the focus of their research. That could be way out of their sphere of expertise. Even though there's no Poker recipe of "which hand beats which" (because strength of language can make a difference), in general ... Weaken - suggesting Alternate > undermining plausibility Explanations of Author's Explanation Strengthen - ruling out Alternate < boosting plausibility Explanations of Author's Explanation

    13% picked this

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