LR Justify the Conclusion

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FlyHigh
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LR Justify the Conclusion

Postby FlyHigh » Tue Nov 08, 2011 12:43 am

The Sufficient Assumption LR questions are killing me. I always narrow it down to 2 choices but then it's literally 50/50, hit or miss. The LG Bible also didn't really help. I've been drilling these, so hopefully that helps.

Does anyone have tips on how to mechanistically approach these?

Thanks!

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tehrocstar
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Re: LR Justify the Conclusion

Postby tehrocstar » Tue Nov 08, 2011 9:11 am

LSAT Blog:Sufficient Assumption Questions | Tips and Categorization
http://lsatblog.blogspot.com/2009/12/su ... -tips.html

This was helpful for me...

Of course...drill drill drill ...

SanDiegoJake
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Re: LR Justify the Conclusion

Postby SanDiegoJake » Thu Nov 10, 2011 5:38 pm

Sure, here's a tip. Even though I know that there is a school of thought that says this doesn't work, I humbly and repsectfully beg to differ. Ultimately, it's about whether it works for you. So try it and see for yourself.

Once you're down to 2 answer choices, use the Negation Test. The Negation test works like this: Negate the answer choice ("What if it's not true that...(answer choice)"). The right answer, if not true, breaks the link between the premises of the argument and its conclusion. The wrong answer, if not true, doesn't necessarily break that link. Give me a couple of questions you're having trouble with and I'll show you exactly how this works. I use it every time.

Do you have PT 62 at your disposal? If so, take a look at some of these questions.

Sect3Ques3: B. What if medication M does NOT have an unpleasant taste? Then, the conclusion does not follow.
Sect3Ques9: C. What if subject's reports are NOT highly susceptible to inaccuracy? The conclusion does not follow.
Sect3Ques15: B. What if Smith does NOT lack insight into her own social circumstances? The conclusion does not follow.

Good luck!

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LSAT Blog
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Re: LR Justify the Conclusion

Postby LSAT Blog » Sun Nov 13, 2011 11:46 pm

While I like the negation test for necessary assumption questions, I don't believe it should be used for sufficient assumption questions.

The reason is that a necessary assumption always needs to be the case in order for an argument to work (the conclusion follow), but a sufficient assumption is just that - sufficient to make the argument work (the conclusion follow), but not all sufficient assumptions are required in order for the argument to work (for the conclusion to follow).

In other words, the correct answer to sufficient assumption questions is often something that does not actually need to be true, but if it is true, will fully justify the conclusion. (Note that many answers to sufficient assumption questions are broader than the argument.)

Take, for example, PrepTest 35 (Oct 2001), Section 1, Question 22 (p226 in Next 10).

Evidence: C -> NOT T -> NOT P
Evidence: P -> T -> NOT C
---
Conclusion: P -> NOT H

While H -> C is sufficient to guarantee the conclusion, it's not required in order to do so. Even if H didn't require C, information from the evidence could still, in combination with a sufficient assumption, guarantee that P required NOT H.

What if we learned that T required NOT H, or that H required NOT T? In combination with the statement that P -> T, the conclusion would still follow from the evidence (even if H didn't require C).

(It's possible that LSAC would disregard the T -> NOT C statement when considering how to make the evidence + sufficient assumption lead to the conclusion - stimuli often contain information that serves as filler and is irrelevant in guaranteeing the conclusion.)

***

Take the statement:

"When your dog encountered my cat in the yard, your dog attacked my cat."

It would be sufficient to prove this statement if we learned, as new information, that when any dog encounters any cat, the dog will attack the cat.

However, this doesn't *need* to be the case in order to prove the statement above. Perhaps some dogs have no problem with cats, but this particular dog was getting back at the cat for being a total jerk.

SanDiegoJake
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Re: LR Justify the Conclusion

Postby SanDiegoJake » Wed Nov 16, 2011 4:39 pm

Yep. LSATBlog offers the other 'school of thought'. I offer my opinion so that you can decide for yourself whether the negation test can be used for sufficient assumption questions as well.

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Jeffort
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Re: LR Justify the Conclusion

Postby Jeffort » Wed Nov 16, 2011 9:54 pm

SanDiegoJake wrote:Yep. LSATBlog offers the other 'school of thought'. I offer my opinion so that you can decide for yourself whether the negation test can be used for sufficient assumption questions as well.


Jake, it is not just a 'school of thought' as you describe it, rather, it is based on valid logic. The negation/denial test is a logically valid technique to apply to necessary assumption questions when evaluating answer choices. Applying it to sufficient assumption/justify the conclusion questions is logically flawed even though it may appear to work to determine the credited answer choice on some (but not all) SA/justify questions.

The reasoning and logic behind why is not a matter of opinion, it is based on the difference of the logical relationship the two different question types require the credited answer choice to have with the argument in the stimulus. They are different question types because the logical criteria for the credited answer choice is different. It boils down to the basic fundamentals of conditional reasoning regarding how sufficient and necessary conditions relate and operate logically.

There are SA/justify questions with a trap answer(s) that states a necessary but not sufficient premise and there are necessary assumption questions that contain an incorrect answer choice(s) that states a premise sufficient to establish the conclusion must be true but that is not necessary to the argument.

Aren't you a TPR teacher? Shouldn't you know this?

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suspicious android
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Re: LR Justify the Conclusion

Postby suspicious android » Sun Nov 20, 2011 10:32 pm

SanDiegoJake wrote:Yep. LSATBlog offers the other 'school of thought'. I offer my opinion so that you can decide for yourself whether the negation test can be used for sufficient assumption questions as well.



WTF?? I'll let LSAT Blog's and Jeffort's responses stand here, and just stick to . . . WTF? San Diego Jake, I've never seen you give such bad advice. Were you joking? Drunk? Either would put my mind at ease.

SanDiegoJake
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Re: LR Justify the Conclusion

Postby SanDiegoJake » Mon Nov 21, 2011 10:02 pm

Ha! No, I never post drunk. And yes, I understand that it's more than a "school of thought" that the only assumption questions in which the negation test works every time are necessary assumptions. It's a logical fact. Believe me, I get it. I just find the whole distinction between necessary and sufficient assumptions a bit "ivory tower" for my taste - LSAT pros arguing with other LSAT pros about a very fine distinction. LSAT takers are different - they'll only see 6-8 assumption questions of any type on the test. My point is that it's often a stumbling block for students who are entirely too concerned with making this distinction, when in reality, they could probably get away with using the negation test every time.

Just trying to help the non-pros. I knew the pros would beat me up here. But I'm always anxious to be proven wrong. Show me. Tell me. Does always using the negation test work for you (test takers, not pros)? Show me some real, recent SA questions where you cannot use the negation test. I provided some where you certainly can...so it certainly works at least sometimes. And frankly, I think it's closer to "almost always" than it is to "sometimes".

Finally, thank you, Android, for the comment. I usually like your stuff as well. I've posted a good bit on this board, so if this is the first WTF I've gotten from you, I think I'm doing all right.

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suspicious android
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Re: LR Justify the Conclusion

Postby suspicious android » Tue Nov 22, 2011 4:57 am

SanDiegoJake wrote:
Just trying to help the non-pros. I knew the pros would beat me up here. But I'm always anxious to be proven wrong. Show me. Tell me. Does always using the negation test work for you (test takers, not pros)? Show me some real, recent SA questions where you cannot use the negation test. I provided some where you certainly can...so it certainly works at least sometimes. And frankly, I think it's closer to "almost always" than it is to "sometimes".


This is just basically telling your students "you're probably not going to be able to figure out the details on this, here's a trick that will work 80-90% of the time". I suppose I might tell my students that if they're really stuck and pressed for time to give it a try. But I feel like you're selling your students short not to force them to understand the concepts behind the questions. I know I'd kick my teacher's ass if he taught me a method he knew not to be reliable and it cost me a point on the LSAT.

Further, I would suggest that this works for you in large part because you are already expert at the ideas and can spot the trap answers fairly easily. So when they sneak in a necessary assumption, it'll probably be pretty obvious to you and you won't even really consider negating it.

yipeng024
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Re: LR Justify the Conclusion

Postby yipeng024 » Wed Nov 23, 2011 7:48 am

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