Q18 - If the recording now playing

[ManhattanPrepLSAT1]

Let's take a look. The stimulus has an underlying argument core that looks like this

If Louie Armstrong + from 1989, then something impossible would happen. Since the impossible doesn't happen and the recording is definitely Louie Armstrong, the recording must not be from 1989.

IN ABSTRACTION

A + B --> something impossible

A is true, so B cannot be true.

(A) isn't employing the use of conditional logic and is therefore incorrect. Where's the "if...then..?"
(B) is is not a valid argument. It logic looks like the following

Properly Titled + from Berthe Morisot --> something impossible

Thus, is not Properly Titled.

The problem with this argument is that it could be properly titled but not be a painting from Berthe Morisot.

(C) is the correct answer. In logical form

17th Century + by Frida Kahlo --> something impossible

It is from the 17th Century, so it must not be by Frida Kahlo

(D) is an invalid argument, besides the fact that it's logical form is also different. Just because Käthe Kollwitz was known for prints does not mean that she was not both a painter and a sculptor.

(E) is also an invalid argument. This argument fails to establish that the portrait was not done by by Elisabeth Vigée-Lebrun. In more formal notation

Portrait + Acrylic --> not by Elisabeth Vigée-Lebrun

It is a Portrait, so it cannot be Acrylic

[clarafok]

hmm i still don't understand why E is wrong, could someone please clarify this?

thanks in advance!

[ManhattanPrepLSAT1]

Answer choice (E) is close but it's missing an element. It should say that the portrait is by Elisabeth Vigee-Lebrun. Without knowing that piece of information we cannot trigger the conditional relationship established in the first sentence.

Does that clear this one up?

[jones.mchandler]

I'm curious as to how it's evident that the sufficient condition in the stimulus is composed of 2 separate parts (if it's Louis + from 1989) as that is all contained within one quotation in the stimulus. I read it as "if it's Louis Armstrong from 1989-->impossible". Is there a key word or turn of phrase that I'm missing?

[Mab6q]

I'm curious as to how it's evident that the sufficient condition in the stimulus is composed of 2 separate parts (if it's Louis + from 1989) as that is all contained within one quotation in the stimulus. I read it as "if it's Louis Armstrong from 1989-->impossible". Is there a key word or turn of phrase that I'm missing?

Hey Jones, I hear your frustration. I got this question wrong on my first try, I think it's a tough one.

With regards to your question, certainly the argument does not set clear conditionals for us like we would see for a SA question. However, the use of the conditionals is simply to see how the author went about his logic:

This recording is Louis Armstrong in 1989 --> he was playing something after his death (impossible)

But we know for sure that it was Louis Armstrong.... so, in order to avoid the implausible conclusion (our necessary condition) that he was playing something after his death, we have to know that the date is wrong. This would ensure that our sufficient assumption is not established, thereby not establishing the implausible conclusion.

So the use of the conditionals is so you can see how the reasoning works.

A + B --> C (impossible)

We have A for sure, but we don't want B because otherwise we would have an impossible conclusion, so it must be the case that B is not true.

[jones.mchandler]

I'm curious as to how it's evident that the sufficient condition in the stimulus is composed of 2 separate parts (if it's Louis + from 1989) as that is all contained within one quotation in the stimulus. I read it as "if it's Louis Armstrong from 1989-->impossible". Is there a key word or turn of phrase that I'm missing?

Hey Jones, I hear your frustration. I got this question wrong on my first try, I think it's a tough one.

With regards to your question, certainly the argument does not set clear conditionals for us like we would see for a SA question. However, the use of the conditionals is simply to see how the author went about his logic:

This recording is Louis Armstrong in 1989 --> he was playing something after his death (impossible)

But we know for sure that it was Louis Armstrong.... so, in order to avoid the implausible conclusion (our necessary condition) that he was playing something after his death, we have to know that the date is wrong. This would ensure that our sufficient assumption is not established, thereby not establishing the implausible conclusion.

So the use of the conditionals is so you can see how the reasoning works.

A + B --> C (impossible)

We have A for sure, but we don't want B because otherwise we would have an impossible conclusion, so it must be the case that B is not true.

Ok I see--thanks for that, really clears it up for me

[MensaNumber]

My real trouble here is not how to answer such questions but how to answer such questions within 1.2mins. Any tips ?

[tommywallach]

Hey Mensa,

Just wanted to let you know that orange folks (your name is orange on the forum) don't get responses from experts. You have to buy a book or a class (blue/green folks) to get prioritized by experts. So you'll hopefully get some posts from other students, but not us teachers.

As to your question, there's no easy answer. Obviously the challenge for everyone is doing the questions quickly! It's just a function of practice and familiarity. Good luck!

-t