Flaw confusion, please help!!!

Giant Panda

Hi guys,

I have some confusion going on here between the difference of the following question:

https://7sage.com/lsat_explanations/lsat-25-section-4-question-23/

https://7sage.com/lsat_explanations/lsat-27-section-1-question-23/

In sum,

From PT25-S4-Q23, we learned that:

If A cause B cause C, then it concludes C causes A; this is wrong because the possibility of C some A, or C and A, is ignored.

If that is true, so why is: PT27-S1-Q23 answer choice A wrong.

If most A cause B, then B, therefore A, the structure of PT25-S4-Q23, then, if we had follow PT27-S1-Q23 logic, it gets down to: (negating "most" to "some not", then it follows that some B is not A is ignored, which is what answer choice A says isn't it?

The 180 Bro_OVO

No.

The stimulus in on PT27, S1, Q23 says:

E ---m---> DLC
DLC(Tom)

---

E

Answer choice A says
There are 10 percent of people who drinks large amounts of coffee are not extreme insomniacs.
This has nothing to do with the stimulus.
Answer choice A is saying 90% of people who drink large amounts of coffee are extreme insomniacs.
Okay? And? Why do we care?

The stimulus tells us that 90% of extreme insomniacs are drink large amounts of coffee. NOT that 90% of Large coffee drinkers are insomniacs.

So, by the stimulus not acknowledging answer choice A. It's not an issue. It's not the flaw.
It is descriptively accurate, but not relevant.

Does this make sense?

Giant Panda

@"The 180 Bro_OVO"

Hi there, I agree 100% of what you had said.

But let's consider the following and ignore the question:

If A cause B cause C, then it concludes C causes A; this is wrong because the possibility of C some A, or C and A, is ignored.

If most A cause B, then B, therefore A,then, some B is not A is ignored,

Is this correct?

BinghamtonDave

I don't think the application of causal reason is that helpful for 25-4-23. 25-4-23 is conditional heavy, not causal. The problem with 25-4-23 is that are given A--->B--->C in the premises and the conclusion states C---->A. Answer choice (B) gives us the negation of this conclusion. This is one of several ways in which the LSAT tests our understanding of sufficient/necessary conditions.
Edit=changing the spelling of "causal" from "casual"

The 180 Bro_OVO

@"Giant Panda"

See BD's response. Does his explanation answer your question ?

BinghamtonDave

For 27-1-23, I have included a visual element to aid in our collective understanding of the flaw. The black squares are the extreme insomniacs. 90% of them drink large amounts of coffee-represented below with the purple dots. As usual, with flaw questions, it will behove us focus on what we are being told in the premises vs what we are being told in the conclusion. Quite often, we could pause after reading the premises in a flaw question and formulate our own, fairly decent conclusion, but the LSAT's conclusion goes into left field. Here is no different: on the basis of 9/10 extreme insomniacs drinking large amounts of coffee, the conclusion is that, the presence of drinking large amounts of coffee indicates extreme insomnia. Deferring to our visual aid: does being a purple dot indicate the "quite likely" possibility of the presence of extreme insomnia? No.

I hope this helps
David

Giant Panda

@BinghamtonDave said:
I don't think the application of causal reason is that helpful for 25-4-23. 25-4-23 is conditional heavy, not causal. The problem with 25-4-23 is that are given A--->B--->C in the premises and the conclusion states C---->A. Answer choice (B) gives us the negation of this conclusion. This is one of several ways in which the LSAT tests our understanding of sufficient/necessary conditions.
Edit=changing the spelling of "causal" from "casual"

@BinghamtonDave

Giant Panda

Your explanation are more than helpful. Thank you very much.

But just to add on. If negation of a invalid conclusion is one way to test a student's understanding for SA and NA mistake, is there other ways besides explicitly stating it out? Do you mind share them from your experience?

Giant Panda

2 ways I have find are: we can have the necessary without the sufficient or some times the necessary condition does not lead to the sufficient