LSAT PrepTest 33 Section 1 Question 20 Explanation | Logical Reasoning

I didn't write the following blog post. It was already on the blog when I took over the URL. The following blog post may contain mistakes. -Steve

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This Logical Reasoning question is from the December 2000 LSAT.


The stimulus describes the predominant theory and presents an argument against it. 4 of the answer choices weaken the argument. The correct choice doesn't weaken it. It may strengthen it or have no effect, but it will not weaken the argument.

Breakdown:

Premise 1: Cave paintings were found on islands off Norway.

Premise 2: The dominant theory about cave paintings is that they describe the painters’ diets at the time.

Premise 3: But there are no animals that clearly depict sea animals, and the painters must have eaten such animals on their trips to the islands.

Conclusion: Therefore, the theory cannot be right.


Analysis:

The “predominant theory” - cave paintings depict the painters’ diets.
The argument against this theory - there's no seafood in the paintings, but seafood must have been part of their diets. We need the answer choice that doesn’t weaken this argument.

Process of elimination is the best strategy in this type of question. Eliminate each answer choice that weakens the argument until you find one that doesn’t.

Remember: Answer choices that weaken the argument against the dominant theory indirectly strengthen the dominant theory.

Let’s look at each choice:

Choice A says cave painters hunted and ate land animals on the island. If this were true, it would weaken the argument in the stimulus. Why? Because it would indicate that the primary diet was land animals. If this were the case, the painters may have painted their diet even if they never painted any sea animals. (Note that the dominant theory relates to the “current” diet of the painters.)

Choice B says parts of the cave paintings didn't survive. If this were true, the parts that didn't survive may have contained pictures of seafood. This would support the dominant theory, weakening the argument against it.

Choice C is correct because it does not weaken the argument against the dominant theory. The fact that the cave paintings depict many land animals doesn’t change the fact that the inhabitants probably ate seafood. They would have painted seafood if the dominant theory were correct.

Choice D weakens the argument because it indicates the painters didn't need to eat seafood. It suggests they could've eaten beef jerky and other dried meats during their voyages instead.

Choice E weakens the argument because it indicates the actual painters never ate seafood.



6 comments:

  1. Sorry, this comment doesn't have anything to do with the LR reasoning question posted, but is one that I think many people may be wondering about. Perhaps the 99th percentile scorers can help us commonfolk out with this one: It seems to be the consensus amongst people I've talked to that section 2 on the June 2005 lsat was the experimental; this is corroborated by the fact that someone on this blog stated that kaplan concurred with this. However, the princeton review website seems to imply that while most individuals do indeed get the same numbered experimental section (section 2 in this case, the topic can vary), there are some tests that have the experimental section placed elsewhere. (e.g 1 or 3) Can anyone verify the truth of this?

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  2. I believe that some students do get the sections in different orders. Therefore, the experimental won't necessarily be the 2nd section for everyone.

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  3. sorry this comment doesn't have anything to do with the experimental section order :-P

    regarding to the LR question, i am not so sure that premise3 should be treated as a premise(from the original text it says, "This theory cannot be right, because the painters must have needed to eat the sea animals populating the waters north of Norway if they were to make the long journey to and from the islands"). i thought it was an argument at my first glance. so there it went...if it is not a "must" for the painters to eat the sea animals, the anwser will weaken the argument.

    i am new here and new for lsat :) please let me know if i have difficulties making those premises.

    -e

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  4. Hi -- this is a good question.

    First off, it's important to note that the sentence containing the conclusion may also sometimes contain additional premises. Here, the relevant sentence, as noted, is as follows:

    "This theory cannot be right, because the painters must have needed to eat the sea animals populating the waters north of Norway if they were to make the long journey to and from the islands, and there are no such paintings that unambiguously depict such creatures."


    The strict conclusion, of course, is that "this theory cannot be right". However, the statement also adds two additional premises (which I doubled up into Premise 3.):

    1. The painters must have eaten seafood on the trips to the islands.

    2. There are no paintings that clearly depict seafood.


    So these two additional premises should be added to the 2 earlier premises to see if they properly add up to the conclusion.

    The reason I see these as seperate premises, and not part of the Conclusion itself, is because the Conclusion explicitly relies upon the 2 subsequent clauses. "This theory cannot be true, BECAUSE..." To me, this is the same thing as saying "....THEREFORE, this theory cannot be true." In other words, where the Conclusion is stated to rely upon a disticnt element in the stimulus, I view that element as a premise, and not as part of the Conclusion.

    (Remember, all arguments consist of Premises and Conclusions. Most Stimuli / LR Questions on the LSAT will contain argument, and will therefore contain both Premises and Conclusions. The first step is to differentiate the Conclusions and the Premises.

    And remember, stated Premises must be taken as true -- but Conclusions may or may not be true. In addition, the RELATIONSHIP between the Premises and the Conclusion that is often assumed by the Conclusion ("Therefore..., Because...") may of may not be valid. In other words, that relationship may logically exist, or it may not. This, of course, is what you're really examining in most LR questions (including this one) -- whether or not the Conclusion truly follows from the stated premises.

    I do, however, understand the uncertainty in this question regarding the final premises contained in the Conclusory statement. For example, even one of the answer choices provided, dealing with dried food, calls into question the validity of one of these premises (that the painters HAD to eat some seafood). If anyone can shed further light on this issue, feel free to post further.

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  5. thanks for j's detailed explanation...that really answers my question :))

    -e

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  6. A better explanation for the correctness of (c) is as such:

    A premise of the stimulus states:

    "The predominant theory about northern cave paintings was that they were largely a description of the current diets of the painters."

    The word 'largely' is key; it leaves room for the fact that 'some' paintings may have depicted land animals. Answer choice uses the word 'many' rather than 'some'. The two are synonymous however, at least on the LSAT.

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