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#20 - The ability of mammals to control their internal body

nadiaguo
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Q 20, Sec 3, Dec 2007 LSAT. It's about brains and body temp. Please explain.
Nikki Siclunov
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Hey nadiaguo,

Thanks for your post. Can you clarify your logic behind choosing the answer you did? It will help us write a more informative explanation if we know how you approached the question in the first place.

Thanks,
Nikki Siclunov
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nadiaguo
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Well I thought it was C because the stimulus states that controlling body temperature leads to the development of brains and intelligence. So if the chemical reactions aren't controlled temperature-wise, then the brain shouldn;t be able to support intelligence.

The whole thing is honestly just a headache to read.
Nikki Siclunov
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You're correct in that (C) is a very attractive answer, and the strongest decoy in this question. Here's how the argument can be broken down:

The author concludes that controlling body temperature is a factor in the development of intelligence.

Premises:

(1) The brain is a chemical machine (Brain --> Chemical Reactions)
(2) All chemical reactions are temperature-dependent (Chemical Reactions ---> Temp.)
(3) Any organism that can control its body temperature can assure that these reactions occur at the proper temperatures. (Control Temp. ---> Assure Proper Temp.)

From these premises, we can easily conclude that the brain is temperature-dependent, and that the chemical reactions in it can be assured to occur at the proper temperature. However, there is a gap between the third premise and the conclusion: how do we know that the development of intelligence depends on the ability of the brain to do that? Herein lies the weakness of the argument.

Answer choice (D) provides the proper supporter assumption: when negated, (D) weakens the conclusion by implying that the development of intelligence is independent of the chemical reactions in the brain taking place at the proper temperatures.

Now, let's look at answer choice (C):

The brain cannot support intelligence if the chemical reactions in it are subject to uncontrolled temperatures.

The logical opposite of (C) would look like this:

The brain can support intelligence even if the chemical reactions in it are subject to uncontrolled temperatures.

Recall that the conclusion is about the development of intelligence in mammals, not the ability of the brain to support intelligence. So, just because the brain can support intelligence in an uncontrolled environment (temperature-wise) does not necessarily mean that temperature is not a factor in the development of intelligence in mammals. Temperature may still be a factor that influences other physiological processes and functions that help in the development of intelligence and have an indirect effect on the brain. Simply put, there is a difference between supporting intelligence and the development of intelligence, which kills (C).

Hope this helps!
Nikki Siclunov
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swong1267
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Why is E incorrect? I tried negating it, and thought that if organisms are not subject to unpredictable chemical processes, then their brains can still develop intelligence even without being able to control the temperature, which weakens the conclusion.
Adam Tyson
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Your negation sounds good, swong, but the effect of that negation is not what you think. It sounds like maybe you are bringing in some outside information or reading into the answer something that isn't provided, and that's a trap you want to avoid at all cost.

When we negate E, we get that organisms that cannot control their body temp are not subject to unpredictable processes. In other words, everything about their processes is predictable. What does that do to the claim that the ability to control body temp is a factor in developing intelligence? Nada. That could still be true. Just because those other organisms are predictable doesn't mean that controlling temp cannot be a factor in developing intelligence. Maybe those predictable organisms don't develop intelligence? Maybe some still do, but control would still have played a part had they been able to exert it?

When we negate the correct answer it should wreck the argument without any outside help or leaps of logic or intuition. You added the idea that those organisms develop intelligence anyway, even without control, but nothing about the argument or answer E provided that information. That was you unintentionally helping that answer to be better than it was! Be aware of when you are doing that, and do your best to avoid helping the answers. Let them stand or fall on their own merits, and you will find that what might have otherwise been attractive wrong answers become much less attractive and less likely to pull you away from better, correct ones.

Good luck!
Adam M. Tyson
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kennypark17
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For answer choice D, can we negate the "not independent" into "is dependent"? Changing that wording made it much clearer to me, but I'm not sure if it's correct or I just got lucky.
Rachael Wilkenfeld
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Hi Kenny,

In general, whenever you see a phrase where the verb is modified by "not" (is not, will not, cannot), you can easily negate the phrase by removing the not. Here answer choice (D) states that the development is not independent of chemical reactions in the brain. To negate that phrase, we simply remove the word not to get the idea that the development IS independent of the chemical reactions.

Hope that helps!
Rachael