PT 31 Section 2 LR question (31-2-21)

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shifty_eyed
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PT 31 Section 2 LR question (31-2-21)

Postby shifty_eyed » Thu Apr 05, 2012 6:00 pm

This is a question about bank deposits, and it asks which of the answer choices exhibit both of the logical flaws in the argument. I don't know what the flaws are, and I am not sure why A would be incorrect.

Any help/insight is greatly appreciated!!

ksinghal
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Re: PT 31 Section 2 LR question (31-2-21)

Postby ksinghal » Thu Apr 05, 2012 6:47 pm

The major flaw is mistaken reversal ("affirming the consequent" in technical terms). Let's isolate that first:

If bank deposit credited same day, then it must have been made before 3pm.

The bank deposit was made before 3pm.

Therefore, the bank deposit must have been credited the same day.


I removed the part about Alicia's knowledge to illustrate the mistaken reversal here. If you didn't see this flaw, you probably misread the first sentence: You probably read "If deposited by 3pm, then credited same day." In reality, it says, "If credited same day, then deposited by 3pm" - just because it was deposited by 3pm doesn't ensure it was credited the same day. Depositing by 3pm is necessary to get same-day credit, but it is not sufficient.

The second flaw is assuming that Alicia's knowledge of the action ensures that she knows the result. Just because Alicia knows the bank deposit was made before 3, even if the bank deposit was credited the same day, this does not logically prove that Alicia knows it was credited the same day.

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shifty_eyed
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Re: PT 31 Section 2 LR question (31-2-21)

Postby shifty_eyed » Thu Apr 05, 2012 7:03 pm

Thanks, that makes sense!

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californihuh
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Re: PT 31 Section 2 LR question (31-2-21)

Postby californihuh » Mon Apr 09, 2012 6:52 am

Is this something recent in Parallel Flaw questions that the LSAT is doing where they tell you how many flaws there are if there's more than one? The question stem asks which of the answers is parallel to BOTH flaws. First time I've seen this.. (Haven't done anything above PT 20 range, so not sure)

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shifty_eyed
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Re: PT 31 Section 2 LR question (31-2-21)

Postby shifty_eyed » Mon Apr 09, 2012 10:35 am

californihuh wrote:Is this something recent in Parallel Flaw questions that the LSAT is doing where they tell you how many flaws there are if there's more than one? The question stem asks which of the answers is parallel to BOTH flaws. First time I've seen this.. (Haven't done anything above PT 20 range, so not sure)


I've seen it a few times before. I wouldn't say it's common, but it's definitely a type of problem you will want to familiarize yourself with IMO because they are tricky!




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