Q21 - It is highly likely that

[jaydizzle]

I narrowed it down to B and E. Is B incorrect because it says people who have not heard of rather than people who are not classical pianists and have not heard of? I crossed out E because to me this was right in the argument. It said the vast majority of people who are not classical pianists do not. So, I figured it did not ignore the possibility.

I was 50/50 on this. This is why I hate LR. When I get a question wrong, I am always left with two answers choices. I thought I was for sure correct with my pick of B since to me E was stated in the stimulus.

[aileenann]

Firstly, I can certainly understand your frustration, but I think you should see that in a way it's a good thing. If you are already at the stage of getting things wrong only because you have it down to two and pick the wrong one, that's huge! Now all you need to do is start fine-tuning your approach so that you go with the correct one when you're down to two.

Now, on the substance of your question. First, let's talk about why B is incorrect. The argument concludes that it is highly likely that C is a classical pianist because she recognizes many of CS's works even though most people who are not classical pianists do not recognize CS's works or even know that CS exists.

I would say the problem in B is that the argument does not do that. The argument says that many people do not even know CS exists and that many people do not recognize CS's works. It may seem to imply that not knowing CS exists precludes recognizing CS's works, but I don't think that has to be the case (think of how many people recognize Beethoven or Mozart because they've heard it a million times before, even if they have no idea who wrote it). So if it doesn't necessarily have to be true for the argument to work, then it's not presumed. So this answer choice does not accurately describe the passage.

Now let's look at the correct answer, (E). I think the easiest way to think about this is first by example. Consider the following argument:

Like most people from NYC, Joe owns an "I heart NYC t-shirt." The vast majority of the people on the planet do not even know what an "I heart NYC t-shirt looks like. Therefore, Joe is very likely from NYC.

Do you see the problem here? The problem is that even if most people from NYC do indeed own such t-shirts, there are only 8 million of them - compare that to the 6 billion people on the planet. That is, even if as a percentage most people in the world don't own an "I heart NYC" t-shirt, there might still be a bigger absolute number of people who are not from NYC who own such t-shirts. And if there is a bigger number of such people outside of NYC than inside, then the probability that random person who owns such a t-shirt is from NYC is not so very high because there are lots of people outside NYC who also own the same t-shirt.

Now you can apply the same logic to the argument about Claudette. While C might behave like this very small/rare group of people, classical pianists, the argument is ignoring that even if in the general population knowing CS's work is very rare, that doesn't necessarily mean anything - there might as an overall number still be more non-pianists who know CS's work than pianists who CS's work, which could undermine the conclusion that it is highly likely that C is a classical pianist.

Does that make sense? This is a really tough problem, so you need to let me know if I haven't made it clear yet!

I'll look forward to hearing your own thoughts and whether you have any additional questions

[jaydizzle]

Sorry for taking so long to respond. I can see why B is incorrect since the argument says people have never heard of CS and that others do not recognize her works. It never makes the leap that B does.

I still don't see how E is correct though. I get your NYC example, but the text in the argument is confusing me.

"The vast majority of people who are not classical pianists do not."

Doesn't this mean that a majority of people who are not classical pianists do not recognize CS works?

To me answer choice E is almost a contra-positive but not quite so.

So, this is the argument:

If you are not a classical pianist then you do not recognize CS.

Answer choice E:

If you recognize CS you are not a classical pianist.

Isn't this different from: If you recognize CS you are a classical pianist? This would be the contra-positive.

So, basically you are saying since the argument didn't assume that choice E could happen it is a flaw?

I think by talking it out like this, I understand this more now.

What if answer choice B said ignores the possibility instead of presumes?

[aileenann]

Thanks for following up

I'm glad it makes sense to you now why B is not the correct answer. I'll go through your response one point at a time.

"The vast majority of people who are not classical pianists do not."

Doesn't this mean that a majority of people who are not classical pianists do not recognize CS works?

Yes, absolutely! It maps onto the NYC example precisely - the vast majority of people who own I heart NYC t-shirts do not live in NY.

I don't know that I would approach this in the conditional sense you advocate. Rather, this is more of a probabilistic question, or a set-membership question, so I do not know that contrapositives will really move you forward in this case.

So, basically you are saying since the argument didn't assume that choice E could happen it is a flaw?

Precisely! The arguments makes statistical assumptions about the world that aren't necessarily true - whenever an argument does that, you can attack it!

[jaydizzle]

I had to read that stimulus maybe 30 times to realize the premise in the argument was different from what answer choice E said.

What if answer choice B said ignores the possibility instead of presumes? Could this be more plausible then. The word ignore in front of E is something I missed when reading the problem. I made myself think it said assumes.

[aquyenl]

A good way to understand this problem is to use numbers. Let's say there are 90 people who are not classical pianists and 10 classical pianists. The stimulus says most classical pianists recognize CS works. So say 8 out of 10 classical pianists recognize CS. Now the stim also says the majority of people who are not classical pianists don't recognize CS. So say 70 out of 90 do not recognize it. But that leaves 20 people who are not classical pianists who do recognize CS works. You end up with 20 who recognize the works but are not pianists and 8 who recognize the works and are classical pianists. 20 vs 8. The argument ignored that there could be more ppl who recognize the works and are not classical pianists than classical pianists.

[ManhattanPrepLSAT1]

Great work! But remember the number of people who recognize CS's works who are classical pianists and of people who are not classical pianists isn't really relevant. The reason being is that this is an argument about likelihoods, not about quantities.

Think of the argument like this. The argument contains several premises:

CP most RW
~RW most ~CP
RW
-----------------
CP (likely)

(Notation Key: CP = classical pianists, RW = recognize CS works)

Using the first and third premise to arrive at the conclusion would be using reversed logic. Using the second and third premise to arrive at the conclusion would require using negated logic.

The argument assumes: RW most CP, so the argument fails to consider that half or more of those who recognize CS's works are not classical pianists.

Hope that helps!

[mcrittell]

CP most RW
~RW most ~CP
RW
-----------------
CP (likely)

(Notation Key: CP = classical pianists, RW = recognize CS works)

How did you get the 3rd premise? If it's from the last sentence, I'm unsure how you translated it as such. Thanks!

[mcrittell]

???

[timmydoeslsat]

I approached this one a little differently than many.

It helps to have seen similar arguments before, it triggers a response!

The argument goes like this:


Classical Pianists most recognize Schumann's works
Claudette recognizes Schumann's works

Non-Classical Pianists most ~recognize Schumann's works
Non-Classical Pianists some ~know Schumann
____________________________________________
Claudette is highly likely a classical pianist


Notice the problem here. We conclude highly likely. That is such a strong claim. Stronger than a general likely, which is more than half.

Do we know the size of these two groups?

What if there are 10 million non-classical pianists in the world and only 50 classical pianists?

Even if most classical pianists have the same belief as what Claudette has, this does not take away from the potential huge gap in numbers representing the two groups.

This reminds of the problem in PT 32, S1, Q17.

[mcrittell]

Matt, now to sound persistent, but I'm still unsure how you got RW as your 3rd premise. Can you explain pretty please? Thanks

[ManhattanPrepLSAT1]

Thanks for being persistent! I meant to get back to your question sooner.

The second sentence says, "Like most classical pianists, Claudette recognizes many of Clara Schumann's works."

That statement actually contains two pieces of information:

1. Most classical pianists recognize many of Clara Schumann's works.
2. Claudette recognizes many of Clara Schumann's works.

So the third premise listed, RW, is just acknowledging that Claudette recognizes many of Clara Schumann's works.

Make sense?

[levyyun]

Before I start rambling, I apologize for my stupidity.

I still don't understand this question, and more so, I cannot figure out for the life of me why answer choice E is the right answer. Previous explanations made little to no sense.

Isn't answer choice E basically contradicting the premise, specifically the third sentence?
"The vast majority of people who are not classical pianists do not [recognize many of Schumman's work]."

Answer choice E:
"Ignores the possibility that the majority of people who recognize many of Clara Schumann's works are not classical pianists"

If it clearly says in the premise that the majority of the people who are not classical pianists do not recognize CS's work, why would I choose an answer that goes against this premise (which is supposed to be held true)?

I am clearly not understanding something. Very discouraged.

[ohthatpatrick]

MOST statements aren't reversible.

Saying "most criminals are men" and "most men are criminals" are two very different claims.

Furthermore, it doesn't contradict to say
"most criminals are men", yet "most men are not criminals".

So (E) is not contradicting anything.

It says
"most ppl who recognize CS's works are not classical pianists"
while the 3rd sentence said
"most ppl who are not classical pianists do not recognize CS's works"

This is exactly the same thing as
"most criminals are men"
yet
"most men are not criminals"

Does that make sense?

To help you understand the argument/flaw/answer choice let me take a step backwards.

Given:
Most Senators are male.
Jackson is a Senator.
===========
can we infer anything?

Yes! We can infer that Jackson is LIKELY a male. That's a valid inference. We're not certain, but we do have probability on our side.

Now consider this one.

Given:
Most Senators are male.
Jackson is a male.
===========
can we infer anything?

No! We can't infer that Jackson is LIKELY a Senator. All we know about Jackson is that he's a male. In order to prove that he's probably a Senator, we would need to know that "most males are Senators". We don't know that.

Similarly, what we have in this argument is this.

Given:
Claudette recognizes many of CS's works.
[missing premise]
==========
Claudette is LIKELY a classical pianist.

Okay, what's the missing premise we need:

"Most classical pianists recognize CS"
or
"Most who recognize CS are classical pianists"?

(re-visit the earlier examples if you're in doubt)

All we know about Claudette is that she recognizes many of CS's works. So we need to start from that point of knowledge and head towards classical pianist.

So we need "most who recognize are classical pianists".

When Flaw answer choices use
fails to consider
ignores the possibility
neglects the possibility

they are essentially Weaken. Just ask yourself, "if true, does it weaken?"

(E) surely weakens. Check out the argument again.

Given:
Claudette recognizes many of CS's works
(E) most ppl who recognize are NOT classical pianists
============
what can we infer?

We can infer that Claudette is probably NOT a classical pianist.

That contradicts the conclusion, so it's a huge Weaken idea.

Hope this helps.

[jh2352]

MOST statements aren't reversible.

Saying "most criminals are men" and "most men are criminals" are two very different claims.

Furthermore, it doesn't contradict to say
"most criminals are men", yet "most men are not criminals".

So (E) is not contradicting anything.

It says
"most ppl who recognize CS's works are not classical pianists"
while the 3rd sentence said
"most ppl who are not classical pianists do not recognize CS's works"

This is exactly the same thing as
"most criminals are men"
yet
"most men are not criminals"

Does that make sense?

To help you understand the argument/flaw/answer choice let me take a step backwards.

Given:
Most Senators are male.
Jackson is a Senator.
===========
can we infer anything?

Yes! We can infer that Jackson is LIKELY a male. That's a valid inference. We're not certain, but we do have probability on our side.

Now consider this one.

Given:
Most Senators are male.
Jackson is a male.
===========
can we infer anything?

No! We can't infer that Jackson is LIKELY a Senator. All we know about Jackson is that he's a male. In order to prove that he's probably a Senator, we would need to know that "most males are Senators". We don't know that.

Similarly, what we have in this argument is this.

Given:
Claudette recognizes many of CS's works.
[missing premise]
==========
Claudette is LIKELY a classical pianist.

Okay, what's the missing premise we need:

"Most classical pianists recognize CS"
or
"Most who recognize CS are classical pianists"?

(re-visit the earlier examples if you're in doubt)

All we know about Claudette is that she recognizes many of CS's works. So we need to start from that point of knowledge and head towards classical pianist.

So we need "most who recognize are classical pianists".

When Flaw answer choices use
fails to consider
ignores the possibility
neglects the possibility

they are essentially Weaken. Just ask yourself, "if true, does it weaken?"

(E) surely weakens. Check out the argument again.

Given:
Claudette recognizes many of CS's works
(E) most ppl who recognize are NOT classical pianists
============
what can we infer?

We can infer that Claudette is probably NOT a classical pianist.

That contradicts the conclusion, so it's a huge Weaken idea.

Hope this helps.

Is this Weaken "test" as reliable as the negation test? If answers use those three and they in fact weaken the argument then will that be the correct answer every time?

[phoebster21]

Sorry for taking so long to respond. I can see why B is incorrect since the argument says people have never heard of CS and that others do not recognize her works. It never makes the leap that B does.

I still don't see how E is correct though. I get your NYC example, but the text in the argument is confusing me.

"The vast majority of people who are not classical pianists do not."

Doesn't this mean that a majority of people who are not classical pianists do not recognize CS works?

To me answer choice E is almost a contra-positive but not quite so.

So, this is the argument:

If you are not a classical pianist then you do not recognize CS.

Answer choice E:

If you recognize CS you are not a classical pianist.

Isn't this different from: If you recognize CS you are a classical pianist? This would be the contra-positive.

So, basically you are saying since the argument didn't assume that choice E could happen it is a flaw?

I think by talking it out like this, I understand this more now.

What if answer choice B said ignores the possibility instead of presumes?

I always try to put these questions into extreme examples to make it easier to understand.

Lets say, hypothetically, there is this realllly rare disease, that 5 people TOTAL in the world currently have. Now, lets say that most of the people with this disease take niquil to help them sleep. So out of these 5 diseased ppl, 3 take niquil, 2 don't. Most of the non-diseased people in this world (lets assume there are 10 billion) do NOT take niquil to help them sleep. Jerome, takes niquil, therefore Jerome must have this disease...

But what if there are 100 thousand people in the world taking niquil but who do NOT have the disease? So we have a total of 105 thousand people taking niquil: 5 rare disease folk and 100 thousand insomniacs .

So while it IS still true that MOST of the diseased folk are taking niquil (3 out of 5) AND while it's ALSO true that MOST of the people who are disease free are NOT taking niquil (since only 100 thousand out of 10 billion are taking it), IT IS STILL true that MOST of the people taking niquil are disease FREE (100 thousand versus 5)....