Do you diagram Justify The Conclusion question types?

nycparalegal
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Do you diagram Justify The Conclusion question types?

Postby nycparalegal » Tue May 11, 2010 7:31 pm

Okay, so I can pretty much get 83% of assumption questions right at this point, but I'm at 40% with Justify the Conclusion. I have a hard time diagramming these questions, and I re-read the LSAT Logical Reasoning Bible over twice and I just don't get these type of questions.

I understand that we're linking two parts of the stimulus, the new information in the conclusion with the information in the premises. I just can't seem to do this quickly enough and sometimes I have a real hard time diagramming these out.

Any thoughts? I've read some of the tips on this question type on the forum and it didn't seem that helpful.

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LSAT Blog
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Re: Do you diagram Justify The Conclusion question types?

Postby LSAT Blog » Tue May 11, 2010 7:41 pm

These are one of the few question-types I often diagram.

What you're describing is the most common format for these types of questions, but not the only format. The correct answer to a Sufficient Assumption (Justify) question is often simply a restatement or the contrapositive.

I'm going over the most common format with formal logic, then with a few examples from real PT questions:

Evidence: A ---> B
Conclusion: C ---> B

Sufficient Assumption #1: C ---> A
Sufficient Assumption #2: NOT A ---> NOT C

Contrapositively...

Evidence: D ---> E
Conclusion: D ---> F

Sufficient Assumption #1: E ---> F
Sufficient Assumption #2: NOT F ---> NOT E



Examples:
PrepTest 31 (June 2000), Section 2, Question 10, p91 in Next 10

Evidence: JR ---> NOT D
Conclusion: FP ---> NOT D

Sufficient Assumption: FP ---> JR


PrepTest 35 (October 2001), Section 1, Question 22, p226 in Next 10

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

Sufficient Assumption: NOT C ---> NOT H
Sufficient Assumption: H ---> C



In a more general sense, the most common formats for Justify the Conclusion (aka Sufficient Assumption) questions, are (in order of complexity):

1. restatement of conclusion / arg
2. contrapositive of conclusion / arg
3. the format in the post I linked above

I've found the 3rd format to be the most common.


I think of Sufficient Assumption Qs as providing information that, if true, would be Sufficient to support the conclusion 100%.

In other words, this information, if true, will guarantee the conclusion's validity.



HTH

-Steve
Last edited by LSAT Blog on Fri Oct 01, 2010 10:57 am, edited 1 time in total.

nycparalegal
Posts: 483
Joined: Sat Oct 17, 2009 11:26 am

Re: Do you diagram Justify The Conclusion question types?

Postby nycparalegal » Thu May 13, 2010 1:17 pm

Does anyone have a mental frame-work of how to approach these questions?

For example, with assumption questions, I think about it as a foundation for the argument being built. I am looking for an answer that must be true for the argument to work, and without it the argument falls down.

What is the mental framework for Justify the Conclusion questions?




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