Premise & Conclusion Analysis Drill #5

[broth99]

Hello,

I just finished Ch.2 of the 2019 LR book and I had a couple questions I was hoping to get clarified.

1) In page 56, the book says "acceptability of the premises does not automatically make the conclusion acceptable. The reverse is also true--the acceptability of the conclusion does not automatically make the premises acceptable". So, I completely understand the first half of that phrase as it is best exemplified by the stimulus about Jacksonville. However, I don't understand how the reverse can also be true because under the truth vs validity section we are told "LSAT makers will let you work under a framework where premises are simply accepted as factually accurate, and then you must focus solely on the method used to reach the conclusion."

2a) For problem 5 in the Premise and Conclusion Drill (i.e. the cookiecutter shark problem), I don't see how the prompt doesn't establish that cookiecutter sharks aren't endangered. When you apply the given fact about these sharks being a minor threat to humans with the following sentence about "fishes that are a minor threat are not endangered", you should get the conclusion that cookiecutter sharks are not endangered.
b) Also, I was wondering if another reason this argument could be considered weak is because there could be other objections to the drilling project like morality or monetary reasons, similar to how the answer key does for the following problem about hog farming.

Thanks,
Barath

[KelseyWoods]

Hi Barath!

1) The statement "the acceptability of the conclusion does not automatically make the premises acceptable" refers to the idea that, again, we are focused on the relationship between the premises and the conclusion--we care about whether or not the premises, if true, prove the conclusion, not whether the premises or the conclusion are true in the real world. So you could have an argument in which the conclusion is something that you agree with or something that you know to be true in the real world. But if the premises stated don't adequately prove that conclusion, then it is not a good argument.

Looking back at the Jacksonville argument, that conclusion might be perfectly acceptable. You might agree that we should move to Jacksonville. But the premises don't provide any clear reason as to why we should move to Jacksonville. So you might accept the conclusion that we should move to Jacksonville, but you don't think the premises I've given have really proven that conclusion.

So yes, we accept the premises as true and ask ourselves whether or not they prove the conclusion. But it doesn't matter whether or not the conclusion is true. Just because premises don't prove a conclusion, doesn't mean that the conclusion is false. Just because a conclusion may be something true or something we agree with, doesn't mean that the reasoning the author has given to support that conclusion is strong.

2a) Remember to read every word carefully! The stimulus does not say that "fishes that are a minor threat to humans are not endangered." Instead, it says "many fishes that are not a threat to humans are not endangered." There are two big differences between your paraphrase and what is actually stated. First, "many" is important here. Even if "many" fishes that are not a threat are not endangered, that doesn't mean that ALL fishes that are not a threat are not endangered. We don't know if the cookiecutter sharks are part of that "many" or not. Second, "not a threat" is not the same thing as "minor threat." Even if cookiecutter sharks are only a minor threat, they are still a threat. Therefore they don't even fit into the same category with the many fishes who are "not a threat." Every word counts on the LSAT so make sure you read closely and rely on the exact wording the LSAT gives you.

2b) Yes, another potential problem with the argument is that even if it had established that the cookiecutter sharks are not endangered (which, again, it did not establish that), that still wouldn't be strong enough to prove that there should be "no objection" to a project which threatens their breeding ground. There could be other objections people might make to the project which have nothing to do with whether or not cookiecutter sharks are endangered.

Hope this helps!

Best,
Kelsey

[argumentace]

Kelsey’s reply does help clear things up, however, I’m still confused why the summary would say “ they aren’t endangered” when the author didn’t explicitly say this. Is this part of the summary based on assuming this is what the author meant by “As many fishes that are not a threat to humans are not endangered, there should be no objection to the new ocean, exploration and drilling projects, which threatens a cookie cutter, shark breeding ground”?

[Dave Killoran]

Yes, the description there captures what the author is driving at--"many fishes that aren't a threat aren't endangered, so because of that there should be no objection to this new drilling project." To go from that first statement to the second, the author has to be thinking the cookiecutter sharks aren't endangered.

Of course, as noted in the analysis at the end, this is a problem because "many" doesn't mean "all," and the cookiecutter shark could still be endangered. In making this assumption, the author commits an error.

Thanks!