December 2000 LSAT Section 1 Question 11

Researchers have discovered that caffeine can be as physically addictive as other psychoactive substances. Some peop...

Sangwook on December 29, 2014

Help

I know why (E) is the answer, but I am still doubt why (C) couldn't be an answer for this question. Let me write out my understanding about a choice (C): "Not all substances to which people can become physically addicted are psychoactive." ===> "Some substances to which....are NOT psychoactive." (1)As far as I'm concerned, I don't find "caffein" is defined as psychoactive substance either explicitly or implicitly on the stimulus. (2)According to the first sentence, caffeine is "as physically addictive as other psychoactive substances." Therefore, I come to the conclusion that there is AT LEAST one physically addictive substance which is not psychoactive. So I am wondering why (C) couldn't be an answer. Please help me out. Thanks,

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Melody on December 29, 2014

The argument states "researchers have discovered that caffeine can be as physically addictive as other psychoactive substances."

As you have pointed out, "caffeine" has not directly been defined as a psychoactive drug, but does that mean it is not one? The argument does not explicitly state what type of drug caffeine is. Therefore, it could still logically be a psychoactive drug.

Further, we are implicitly told that "caffeine" is a psychoactive drug.

The last sentence states: "as many people consume caffeine as consume any one of the other addictive psychoactive substances." Saying "any one of the other," implies that there are "other" addictive psychoactive substances other than caffeine--this implicitly includes caffeine as a part of the overarching group of addictive psychoactive substances.

So, for these reasons, we cannot logically conclude that "not all." i.e. at least one, "substances to which people can become physically addicted are psychoactive."

Whereas, we have been explicitly told that an equal amount of people consume caffeine" as those who consumer any other addictive psychoactive substances."

So, the argument tells us that there is no physically addictive psychoactive substance that is consumed more than caffeine is, i.e. answer choice (E).

Hope that clears things up! Please let us know if you have any other questions.