LSAT 5 | Section 3 | Logical Reasoning: Q5

LR Question 5 Explanation

QUESTION TEXT: Animals with certain behavioral disorder have unusually high…

QUESTION TYPE: Necessary

CONCLUSION: Animals with a certain behavioral disorder can be cured by being treated with a silicon based compound.

REASONING: The compound binds to aluminum, a metal that is unusually high in the brain tissues of the affected animals.

ANALYSIS: This sounds like a good argument, but…do you know anything about the effects of silicon, or of aluminum? We don’t even know anything about the disease. Does aluminum cause it, or is it a symptom? Are there other causes/symptoms?

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1. If aluminum levels are invariable, then silicon won’t help. Aluminum levels will stay the same.
2. CORRECT. If aluminum is merely an effect of the disorder then removing it likely won’t cure the disease.
3. This sounds very tempting. But it’s not necessary that there are no side effects at all. It’s only necessary that silicon can cure the disease. (technically, the argument wasn’t claiming that treatment was a good idea)
4. This doesn’t affect the argument at all. The treatment could still work if an elephant required more silicon than a mouse.
5. The argument says that the animals’ brains have “unusually high” levels of aluminum. This implies that normal brains have some.

Recap: The question begins with “Animals with certain behavioral disorder have unusually high”. It is a Necessary Assumption question. Learn how to master LSAT Necessary questions on the LSAT Logical Reasoning question types page.