LR Question 18 Explanation, by LSATHacks
QUESTION TEXT: Zoologist: Every domesticated large mammal species now…
QUESTION TYPE: Necessary Assumption
CONCLUSION: It would be hard or worthless to domesticate the remaining large wild mammals.
REASONING: Past generations would have tried to domesticate every large mammal which seemed worth domesticating.
ANALYSIS: The premise of this argument is that people would have tried to domesticate any seemingly useful large mammal. Since some mammals aren’t domesticated, those animals must not have seemed useful, or have been hard to tame.
So far so good. But then the conclusion is that now, none of those species are worth domesticating, or easy to domesticate. But things change. There are at least three possible flaws here:
- With our modern techniques, maybe it’s much easier to domesticate animals now.
- Ancient peoples only tried to domesticate animals that seemed useful. The conclusion is about whether mammals are worth domesticating.
- Maybe some animals were not useful in the past, but would be useful in our modern economy.
___________
- The argument was only about species that seemed worth domesticating. It doesn’t matter whether people tried to domesticate animals that weren’t worth domesticating.
- CORRECT. If it’s much easier to domesticate animals today, then maybe we could domesticate a few more mammals.
Negation: It is much easier to domesticate large mammal species than it was in the past. - It doesn’t matter if some species went extinct. The conclusion is about existing species.
- Use the negation test on necessary assumption questions. The negation here is: “There isn’t always a correlation between how easy it is to domesticate an animal and how worthwhile it is.”
That has no impact on the conclusion. Why the devil would such a correlation matter? We only care about: i. can you do it? ii. Is it worth it? - Why would this matter? We don’t care how easy it was to domesticate goats or cows.
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Is there a difference in necessary assumption and sufficient assumption questions? Q16 was sufficient assumption but this one is necessary assumption. Is there a way to tell the difference and is the difference matter in picking answer?
Yes, there is a significant difference between necessary and sufficient assumption questions. Necessary assumption questions are asking you to find an (implicit) assumption that is required by the argument in order for the conclusion to follow from the premises. If you negate the necessary assumption, then the conclusion will not follow from the premises. That’s why one test to determine if the answer choice you selected is indeed the necessary assumption is to negate the answer choice and then plug the negation back into the stimulus. If the argument falls apart, then you’ve found your necessary assumption. You can determine if a question is a necessary assumption question by looking at the question stem; if the question stem asks you to find an assumption that is “necessary” or “required” by the argument, or that an argument depends/relies on, that’s a necessary assumption question.
A sufficient assumption question is asking you to find the answer choice that provides additional information that will ensure that the conclusion follows from the premises. Sufficient assumptions make an argument air-tight, but they are not required in order for the conclusion to be valid. There could be many possible sufficient assumptions that could make an argument valid. If the question stem asks you to find an answer choice that is sufficient in order for the conclusion to be true, or that would allow the conclusion to be “properly drawn”, or that would “justify” an argument, you’re looking at a sufficient assumption question.
You can find more information about how to deal with these question types in the LSAT Hacks course: https://lsathacks.com/product/lsat-course/
Or in the LR Mastery Seminar: https://lsathacks.com/product/lr-mastery-seminar/
Lucas you are amazing, thank you!
i thought that we couldnt attack the conclusion. doesnt this question do just that?
This answer choice isn’t attacking the conclusion, it’s simply providing new information that doesn’t necessarily contradict what we’ve been given. The answer choice makes a comparative claim about methods today versus methods in the past. So, even if the conclusion claims these animals would be difficult to domesticate today, that doesn’t exclude the possibility of it being either easier or more difficult today to domesticate animals in general than it was in the past.
Hey Graeme, i understand why B works, but for answer choice A, i was under the impression that in order for the conclusion to flow, the assumption that people have tried to domesticate every wild large mammal species at one time or another would work for this question, since if they had tried, and failed, then it would no longer be worth domesticating or it would be difficult. Thoughts?
>since if they had tried, and failed, then it would no longer be worth domesticating or it would be difficult.
Not true. It’s possible that it’s become easier for us to domesticate animals, or that our needs have changed so that some undomesticated animals would now be useful to domesticate.
>since if they had tried, and failed, then it would no longer be worth domesticating or it would be difficult.
I think you’re thinking in sufficient assumption terms, which is 100% the wrong way to approach necessary assumption questions. You shouldn’t be thinking about the answer itself and what happens if it’s true. You have to think about the NEGATION of the answer, and what happens if the answer isn’t true.
You have to ask yourself: “Would the argument be destroyed if humans had tried to domesticate all but one large mammal species.”
That’s doesn’t even affect the argument, so the original assumption can’t be necessary.
The explanation is for section 3 number 18, not section 1 number 18
I double checked, it’s for section I. Do you have a pirated copy of the test? Sometimes their order is different.
On the official preptest 65, section III is reading comprehension.