#23 - Linda says that, as a scientist, she knows that no

[kristinaroz93]

Hi Steve,

yes, what I understood is that my new explanation of e is correct=)

And for question one, if the most arrow was facing the other way as I posed earlier, would it still lead to the same conlusion ? =D

Thanks in advance! You have been very helpful to me

-kristina

[Steve Stein]

Hey Kristin,

What I took from your last message was that you understood my point that your explanation from your previous post was valid

As for your second question, your explanation was valid on that one as well. If most A's are B's that means there is at least one being that is both an A and a B. And the same can be said if most B's are A's.


I hope that's helpful! Please let me know whether this is clear—thanks!

~Steve

[kristinaroz93]

Yes, thank you! =DD

[Johnclem]

Hello ,
Could some please check my understanding for this flaw question. I am practicing what I could or cant infer from the set of premises. ( as I am out of drills in my book ).
I believe the flaw here is making a claim about people in general when we have info only on scientists.


1) If you are a scientist ---> appreciate poetry
~appreciate poetry------->you're not a scientist .

2) scientists <MOST> Logical

c: people who appreciate <SOME> illogical

What we can infer :

1- some scientists who don't appreciate poetry are logical .
2- if one appreciates poetry then they are not a scientist
3- if most scientists are logical then it's possibles some are not ( depending on if most here includes all or not ).

What we can't infer :
1- anything about people whom are not scientist


Thanks
John

[Kristina Moen]

Hi John!

I'm glad you are using this forum to check your work! It's a good way to use your resources and to study for the test. Keep it up!

You are correct that this argument contains conditional reasoning, so a good approach is to diagram the conditional relationships.

The first sentence "no scientist appreciates poetry" means that there is NO ONE in the group of both scientists and poetry appreciators. These groups are mutually exclusive. For example, "No dogs are cats" means that if you are a dog, you are not a cat. If you are a cat, you are not a dog.

So you would diagram the first sentence as:
Scientist Don't appreciate poetry and Appreciate poetry Not a scientist. Another way to write this is Scientist Appreciate poetry.

You have the 2nd and 3rd sentences correctly diagrammed:

The 2nd sentence "Most scientists are logical" can be diagrammed as:
Scientists Logical.
This is a premise.

The 3rd sentence "at least some of the people who appreciate poetry are illogical" can be diagrammed as:
Appreciate poetry Illogical
This means that there exists some people in both groups of poetry appreciators and illogical people. This is the conclusion.

So what we have is:
Scientist Appreciate poetry
Scientists Logical
Thus, Appreciate poetry Illogical

Your inferences from the premises are correct. And you are correct that we cannot infer anything about non-scientists. That's the flaw! Great job, John.

[jessicamorehead]

Hi!! I want to make sure I understand these types of questions.

Stimulus:
Premise: scientist NOT appreciate poetry
Premise: scientist logical
Conclusion: appreciate poetry NOT logical
Is the flaw that we know nothing about those who appreciate poetry, besides that they are NOT scientists (CP of premise 1)?

Answer choice A:
Premise: M NOT LE
Premise: M NA
Conclusion: NA NOT LE
Reading this through without diagramming, I found this to be valid. However, when I diagrammed it, I suddenly got confused as to how this is valid. Can I substitute the second premise into the first premise because the common "M", which would make the conclusion true? For instance, M NA NOT LE. Why did the conclusion change from "most" to "some"?

Answer choice B:
Premise: F NOT CEC
Premise: F adults
Conclusion: CEC children
All we for sure know about CEC is the CP of premise 1, which is CEC NOT F. So we cannot prove the "children" part in the conclusion, right? This matches the flaw in the stimulus.

Answer choice C:
I eliminated this one because the premise didn't seem to match "equal to" and the conclusion was off "at least the best." Was that a valid reason to eliminate this answer choice, or is there a better reason?

Answer choice D:
I eliminated this one because the conclusion was relative "less," while the stimulus' conclusion was absolute.

Answer choice E:
Premise: CE NOT LPT
Premise: CE honest
Conclusion: LPT honest
How do the premises connect to make the conclusion? Because if I contrapose premise 1, to match the LPT in the conclusion, then premise 1 and 2 cannot connect since one would have CE and the other would have NOT CE.

General Questions about "some" vs "most":
For "some" statements in conditional logic, I understand that you can switch the sides since "some" reads both backwards and forwards. Can you ever contrapose "some" statements/would you ever need to?

For "most" statements in conditional logic, the arrow is always one way. Can you switch the sides if you negate them? Or would that mess up the "most?" For instance, would the second premise of this problem be equivalent to NOT logical NOT scientist? Or do we know know anything about those who are NOT logical because we cannot contrapose "most" statements?

I really want to completely understand these types of problems, so I can become faster at them. I appreciate whoever takes their time to answer this very loaded question of mine!

Thanks,
Jessica

[Alex Bodaken]

jessicamorehead,

Thanks for the question! Let me see if I can help.

(A): When it comes to formal logic (which is what we have here given the "all" vs. "some/most" language), it can get a little tricky to diagram. So let's think it through - we know that no marsupials lay eggs. And we know most marsupials are native to Australia. The conclusion then does follow that some animals native to Australia lay eggs - after all, every one of the marsupials in Australia (of which we know there are at least one) won't lay eggs, which validates the conclusion.

(B): Correct - the certainties of this question (all then most then some) match the stimulus, and the flaw does too - we can't prove anything about the people who want children to eat candy (just as we couldn't prove anything about the people who appreciate poetry in the stimulus).

(C): Yes - those are both errors and valid reasons to eliminate this answer.

(D): Yes - that is the problem with this answer.

(E): Here's the issue with this answer: both the stimulus and this answer choice describe two groups in their conclusions...in the stimulus it is the people who appreciate poetry and those who don't, while in the answer choice (E) it is people who like to pay taxes and those who don't. But, in the stimulus those people are described differently (those who appreciate poetry are illogical while those who don't are logical), while in this answer choice they are the same (both those who like and don't like to pay taxes are honest). Because that doesn't match, this answer choice is wrong.

Hope this helps!
Alex

[jessicamorehead]

Alex,

Awesome! Thanks for the reply. I think I was getting too caught up in the diagramming, which was slowing me down and basically complicated things more. When I just redid this problem without thinking about it in terms of diagrams, it made a lot more sense. I could immediately eliminate A because the conclusion was valid, C because of the premise differences, D because of the absolute/relative difference in the conclusions, and E because of what you just described - the stimulus discusses logical vs illogical, whereas E discusses honest vs honest. Feels good to get faster at these types of questions! Thanks so much for the help!

Jessica

[Alex Bodaken]

jessicamorehead,

No worries, happy to help! One of my absolute favorite articles from our blog (which is saying something, since there's a lot of good ones!) is this one on not get trapped into seeing conditional reasoning everywhere:

https://blog.powerscore.com/lsat/bid/28 ... Everywhere

Good luck in your continued studies!
Alex

[maevemahoney]

Hello,

Can someone please help me understand why A is not correct? I had it narrowed down between A and B.

My diagram of the stimulus is:

Scientists (crossed out) Appreciates Poetry
Scientists Logical
People Appreciates Poetry (crossed out) Logical

My diagram of answer A is:

Marsupials (crossed out) Lays Eggs
Marsupials Native Australia
Animals Native Australia (crossed out) Lays Eggs

My diagram of B is:

Fathers (crossed out) Wants children eat candy before bedtime
Fathers Adults
Wants children eat candy before bedtime Children

A seems more like it follows the same structure as the stimulus so I am confused why this is wrong.