Logical Reasoning--Sufficient and Necessary Conditions?

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LSAT_Padawan
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Logical Reasoning--Sufficient and Necessary Conditions?

Postby LSAT_Padawan » Mon Mar 22, 2010 6:45 pm

Paraphrasing the question:

If you know a lot about history, you can impress people who are intellectuals. But unfortunately you will not know much about history if you have not for example, read a lot of books. Therefore, if you are not well versed in history due to lack of reading, it will not be easy for you to impress people who are intellectuals.

The argument's reasoning is flawed because the argument overlooks the possibility that

(A) many intellectuals are not widely read in history
(B) there are people who learn about history who do not impress intellectuals
(C) it is more important to impress people who are intellectuals
(D) there are other easy ways to impress intellectuals that do not involve knowing history
(E) people who are not intellectuals can be impressed more easily than people who are intellectuals

I know how to diagram the sufficient and necessary conditions according to the S --> N format but I don't understand how this diagram can equate to (D) being the correct answer. Can someone please explain the missing link to help me understand? My diagram is below:

KH = know a lot about history; IPI = impress people who are intellectuals

P1: KH --> IPI
C: not KH --> not IPI

Thank you for your enlightenment!

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Atlas LSAT Teacher
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Re: Logical Reasoning--Sufficient and Necessary Conditions?

Postby Atlas LSAT Teacher » Mon Mar 22, 2010 7:11 pm

I think you may be approaching this a bit too formally (or at least more formally than you need to).

The core of this argument is that if you're not well-versed, you can't impress (or, it's "not easy"). Why? Because if you are well-versed, you can impress.

It's back to this sort of thing:

If you leave, I'll cry.

Therefore, if you don't leave, I won't cry.

Which is clearly flawed.

(D) notes the flaw that just because knowing history allows you (is sufficient for) impressing intellectuals, it's not the only way. Perhaps just being alive is sufficient for most people to impress those pipe-smoking smart-pants.

Perhaps this seems too pared down to you, but I think this is the way to approach this quickly -- get down to the core, see the gap (flaw), and then evaluate the answer choices. The second sentence is unimportant in seeing the flaw. As for the other choices.

(A) irrelevant -- no reason to think they need to be well-read
(B) tempting, but you need to know a lot about history, not know something to impress intellectuals
(C) out of scope
(E) out of scope

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LSAT_Padawan
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Re: Logical Reasoning--Sufficient and Necessary Conditions?

Postby LSAT_Padawan » Mon Mar 22, 2010 7:25 pm

Thank you Atlas LSAT Teacher. I think I get it now. The flaw in the conclusion of the argument as it relates to the premise is an incorrect negation (IN) so just because one does not know a lot of history doesn't necessarily mean one cannot impress snotty pipe-smoking smarty pants. I could be rich and affluent or I can live a bohemian minimalist lifestyle and that may impress the intellectual.

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Atlas LSAT Teacher
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Re: Logical Reasoning--Sufficient and Necessary Conditions?

Postby Atlas LSAT Teacher » Mon Mar 22, 2010 8:55 pm

Nice -- looks like you got it.

Now go bohemian.




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