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#21 - Cognitive psychologist: The majority of skilled

GLMDYP
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Cognitive psychologist: The majority of skilled artists are very creative people...[Question content removed by Admin. LSAC rules unfortunately do not allow the posting of the text of complete LSAT questions. But, if you give us the test date or PrepTest number, the section, and the question number (which I put into the question title), we can find it easily and still answer the question. Thanks!]


I know this have something to do with formal logic, but I'm confused.
Thanks!
BethRibet
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Hi,

Thanks for your question. Yes, this is a formal logic problem. We can respond further if you can articulate a more specific question, or explain how you've tried to solve it. But in essence, the idea is as follows:

The majority of skilled artists are creative.
Creative = good at abstract reasoning. (inference, the majority of skilled artists are good at abstract reasoning).
Some skilled artists are not famous.
Conclusion: some people good at abstract reasoning are famous.

As presented, this conclusion is fallible or uncertain, because we don't have a way to know that the skilled artists who are good at abstract reasoning overlap with those who are famous. Answer choice E fixes that problem. If most skilled artists are famous, then there's no way that none could be good at abstract reasoning, because we already know that the majority of skilled artists are good abstract reasoning. That is, "the majority" and "most" can't be completely separate, they are both more than 50%, and will have to overlap to some degree.

Hope that helps!
Beth
GLMDYP
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Now I understand! Thank you! :-D
agroves
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Hello,

This question has me stumped. Can you please walked me through this one, particularly working the language of majority/some into a diagram?

Thank you!

Angela
Jacques Lamothe
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Hey Angela,

Putting terms like most, some, and majority into diagrams can be tricky. Those terms prevent us from diagramming sentences as conditionals with contrapositives. But it can still be useful to write them out and some of the sentences in this stimulus can be represented as conditionals.

We know that "the majority of skilled artists are very creative."
We know that "very creative --> good at abstract reasoning."
And we know that not all skilled artists are famous.

We are looking for the answer choice that, when combined with that information above, produces the conclusion that "Some people who are good at abstract reasoning are famous."

Answer choice E ends up being correct. Keep in mind that you only need to prove that some people good at abstract reasoning are famous. We know that the majority of skilled artists are very good at abstract reasoning because we can combine the first two pieces of information that we got from the stimulus. Then, If most skilled artists are famous some of the famous artists will be good at abstract reasoning. The trick to seeing this is to think of what the terms majority and most mean. They both mean more than 50%. If, hypothetically, 51% of skilled artists are good at abstract reasoning and 51% of skilled artists are famous, at least some of the ones that fall into the "good at abstract reasoning" category will also fall into the famous category. So while diagramming terms like 'some' and 'majority' is difficult, understanding the quantities that those terms refer to and how they relate to other quantities is the secret to answering questions that use the terms.

I hope this helped!

Jordan
AnnBar
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Hello,

I picked answer choice A.
I diagrammed the stimulus as follows:

Skilled artist :most: creative people
creative people :arrow: good @ AR
not all skilled artists :arrow: famous (had a hard time diagramming this one)
Abstract reasoning :some: famous (conclusion)

I thought I needed to find a link between abstract reasoning and skilled artists. So my thought process for A was
Skilled artists :most: abstract thinkers we can then infer abstract thinkers :some: skilled artists
The issue there, it that I end up with 2 some chains which do not really provide an inference, so I think that is why A is incorrect?


Answer E
We end up with the chain
Skilled artists :most: Abstract reasoning
Skilled artists :most: famous (Answer E)
which can also mean famous :some: skilled artists (which included in that chain is famous :some: Abstract reasoning & famous :some: creative people.
Could you let me know if the logic is correct. Hope it all makes sense.

Thank you
Eric Ockert
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Hi Ann

The first two rules can be placed into a chain that looks something like:

SA :most: VC :arrow: GAR

You can drop the common term of VC to arrive at the inference of:

SA :most: GAR

Note that this is the same statement that answer A gives you. In effect, answer A isn't adding any additional information to this argument, it just leaves you where you started.

The final rule in the stimulus can be drawn like so:

SA :some: NOT F

But be careful with this rule. Even though it tells you that SOME skilled artists are NOT famous (not all = some are not), it doesn't tell you how many skilled artists ARE famous. Answer (E) does provide that quantity...more than half. So if we put our combination of the first two rules side by side with answer (E) we see:

SA :most: GAR (combination of first two rules above)
SA :most: F (answer choice E)

Imagine there are 100 skilled artists. The first rule demands at least 51 skilled artists are good at abstract reasoning. The second rule also demands that at least 51 skilled artists are famous. You cannot have two independent groups of 51 in a pool of 100. This guarantees that there is at least one skilled artists who is BOTH good at abstract reasoning and famous. Therefore, our conclusion GAR :some: F must follow logically.

Hope that helps!
Eric Ockert
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Eric Ockert wrote:The final rule in the stimulus can be drawn like so:

SA :some: NOT F

But be careful with this rule. Even though it tells you that SOME skilled artists are NOT famous (not all = some are not), it doesn't tell you how many skilled artists ARE famous.


I ignored the statement 'not all skilled artists are famous' in the stimulus but managed to get this question correct. But I am trying to review this statement because it can be very misleading. I know that not all means some are not, but I would like to clarify the following: when it says not all skilled artists are famous, is it wrong to represent it as
Skilled Artists :arrow: Not Famous

Otherwise, how would the above diagram with just conditional statements be expressed?
student987
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I'm really confused about the purpose of having "However, not all skilled artists are famous" in the stimulus; I feel like it's not at all relevant to the logic of the argument. That is, the stimulus and answer choice would be perfectly fine without this sentence.

I'm a bit confused about what to make of this situation. Are there times when this happens? And is my analysis correct?
Thank you!
Robert Carroll
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L,

That representation is incorrect. This statement is not a conditional and cannot be diagrammed as a conditional. A statement that some things have (or lack) a certain property, or (equivalently) that not all things lack (or have) a certain property, just isn't a conditional. It's a "some" statement and has to be diagrammed as shown in Eric's post above.

student,

It is somewhat rare, but not unheard-of, for a particular premise not to be used in an argument at all. This is such a case. The statement you quote is not necessary for the argument and does nothing to prove the conclusion. With answer choice (E) added to the argument, there is no need at all to have that quoted statement.

Robert Carroll