PT 34, Section 2, #10, Assumption Question

icanreadgood
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PT 34, Section 2, #10, Assumption Question

Postby icanreadgood » Wed Jun 02, 2010 7:53 pm

for some reason i just can't figure out this assumption question. I understand the assumption is between students with special educational needs and students with learning disabilities. I narrowed down my options to A and D. Then I chose A as my answer, and it turns out it is "just the opposite of what the argument is assuming." For some reason I cannot see that. Also, isn't the negative of the right answer supposed to make the conclusion false? I see that A does that. Can someone please explain this to me, maybe with logic diagrams or some other easy to understand method? I read the Kaplan test explanation and it did not help me.

Thanks in advance

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LSAT Blog
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Re: PT 34, Section 2, #10, Assumption Question

Postby LSAT Blog » Wed Jun 02, 2010 10:24 pm

This is a sufficient assumption question.

The argument claims that because there are no students with LD, there are no students with SN.

In other words, the argument is a conditional statement:

NOT LD ---> NOT SN


The correct answer is simply the contrapositive:

SN ---> LD

"The only" is a sufficient condition indicator.

***

Providing the contrapositive of the argument as new information in an answer choice fully justifies the original argument itself.

If the contrapositive of something is true, then the original must be true as well.

(Negating the correct answer choice to see whether the argument falls apart is a technique you can use for necessary assumption questions, but it's not wise to use it for sufficient assumption questions. The correct answer to sufficient assumptions is often something that does not actually need to be true, but if it is true, will fully justify the argument.

Yes, I know Kaplan doesn't distinguish between Necessary and Sufficient Assumption questions in its materials. This is a mistake because there are big differences between these two question-types.)

Hope this all helps. Please feel free to PM if you'd like more info about the difference.

-Steve

icanreadgood
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Joined: Mon Mar 22, 2010 3:40 am

Re: PT 34, Section 2, #10, Assumption Question

Postby icanreadgood » Wed Jun 02, 2010 11:33 pm

You are soooo smart, thank you!

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Knock
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Re: PT 34, Section 2, #10, Assumption Question

Postby Knock » Thu Jun 03, 2010 4:50 am

LSAT Blog wrote:This is a sufficient assumption question.

The argument claims that because there are no students with LD, there are no students with SN.

In other words, the argument is a conditional statement:

NOT LD ---> NOT SN


The correct answer is simply the contrapositive:

SN ---> LD

"The only" is a sufficient condition indicator.

***

Providing the contrapositive of the argument as new information in an answer choice fully justifies the original argument itself.

If the contrapositive of something is true, then the original must be true as well.

(Negating the correct answer choice to see whether the argument falls apart is a technique you can use for necessary assumption questions, but it's not wise to use it for sufficient assumption questions. The correct answer to sufficient assumptions is often something that does not actually need to be true, but if it is true, will fully justify the argument.

Yes, I know Kaplan doesn't distinguish between Necessary and Sufficient Assumption questions in its materials. This is a mistake because there are big differences between these two question-types.)

Hope this all helps. Please feel free to PM if you'd like more info about the difference.

-Steve


Wow. I think this could be the source of my assumption problems. I thought the negation technique could work on any assumption question. Do you have any place on your blog where I could read some more about this? thank you!

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Re: PT 34, Section 2, #10, Assumption Question

Postby LSAT Blog » Thu Jun 03, 2010 12:00 pm

Knockglock wrote:Wow. I think this could be the source of my assumption problems. I thought the negation technique could work on any assumption question. Do you have any place on your blog where I could read some more about this? thank you!


Sure, Knock!

Difference Between Necessary & Sufficient Assumption Questions

This contains some examples of Suff Ass questions where the correct answer doesn't NEED to be true. (I don't know why people don't refer to that type as Suff Ass more often :) )


Here's where I talked about them in recent threads:

viewtopic.php?f=6&t=117372#p2958215
viewtopic.php?f=6&t=66094&start=1125#p2966479

***

@icanreadgood

Glad to help!




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