Q24 - Money doesn't exist

[ManhattanPrepLSAT1]

This question definitely relies on conditional logic. And it's in a form that most people are not familiar with... I found it rather confusing as I started to see this chain of logic appear on the LSAT myself.

I think the best way to get to the assumption is baby steps in the abstract.

Suppose you had an argument

X
---
Y

We could say that the assumption is X --> Y, because if we add it to the argument

X --> Y
X
------
Y

It works out perfectly

Try this one now

X --> Y
----------
Z

It's a bit trickier but it just uses a conditional as a condition of a greater conditional and the assumption is
(X --> Y) --> Z (In plain english... if all x's are y, then z must be true.)

The full argument would read

(X --> Y) --> Z
X --> Y
-----------------
Z

For number 24...

LB --> D
----------------
~E


LB = loss in belief
D = disappear
~E = doesn't exist

And it reads in plain english a loss in belief would make something disappear, therefore it doesn't exist.

The assumption would read (LB --> D) --> ~E

If a loss in belief would make something disappear than it doesn't exist

By contrapositive, if something exists then a loss in belief in it wouldn't make it disappear. Pretty close to answer choice (A).

[ManhattanPrepLSAT1]

I can think of a couple others, but can't remember from which PrepTests they're from. If I run into them, I'll post them here.

Your contrapositive work above is perfect!

[ocho34]

I have a question about the phrase "even if" in choice (A).
Is "even if" one of those terms that introduce a necessary condition (such as then, only, etc..)?

So for choice (A) is it okay to diagram it as E-->LB
?

[ManhattanPrepLSAT1]

The best way to think about "even if" is to ignore it!

So, for example...

Even if the fog roles in, the boat will sail.

You would NOT diagram this

FR --> BS

Instead, it merely says

BS

This is not a conditional statement, but rather a a statement of fact. So, you ignore the even if part, and state that the other part will happen regardless.

Let me know if this needs further elaboration. This can be tricky.

[noah]

I ended up explaining this on another forum, where someone was confused between (A) and (B) so I figured I'd re-print my two cents here:

I'm not sure this argument is easily-attacked through diagramming.

As you're reading missing assumption questions, your mind should be constantly looking for the gap. The conclusion is that money does not exist. The proof: we could make it disappear if we all stopped believing in it. What's not said is why this proves it doesn't exist. Maybe things can disappear when we stop believing in it but still be considered to exist right now (or perhaps existing can continue once you disappear? invisible ink, for example). Regardless, in this problem, there's an assumption that this phenomenon proves something is not real, and so we're assuming that a real thing would react differently to us not believing in it.

(A) fills the gap quite nicely, while (B) doesn't help the argument since it would only show that money does not exist if it was proven that we have a mistaken belief about money. BTW, the fact that we're mistaken about money doesn't count as the mistaken belief, as that would be circular and, more importantly, the conclusion isn't actually that there's a mistaken belief about money, just that it doesn't exist (it's never explicitly mentioned that we all think it does exist).

An analogous argument might be: I know that Patty is kind because if we all teased her, she would cry. For that argument to be drawn properly we'd need to know that our kindness litmus test really works: that if she were not kind and we teased her, she would not cry.

[mrudula_2005]

For number 24...

LB --> D
----------------
~E


LB = loss in belief
D = disappear
~E = doesn't exist

And it reads in plain english a loss in belief would make something disappear, therefore it doesn't exist.

The assumption would read (LB --> D) --> ~E

If a loss in belief would make something disappear than it doesn't exist

By contrapositive, if something exists then a loss in belief in it wouldn't make it disappear. Pretty close to answer choice (A).

So you translated "All that would be needed to make money disappear would be a universal loss of belief in it" as "universal loss of belief" being the sufficient condition and disappearing being the necessary condition. How did you know that? When I see the "needed" in the sentence "All that would be needed" I think to myself "okay, here is the necessary condition" and so I would have thought that LB would be the necessary condition...

or is it the context that is key...the "All that would be needed to make..." (intuitively I understand how it indicates sufficiency but the "needed" throws me off) - is there a hard and fast rule on how to interpret and translate this precise type of sentence?

can you help me follow your translation? thanks a lot.

[ManhattanPrepLSAT1]

Another great question. This one is tricky at first, but as soon as you see it a few times, you'll catch it every time.

If only one thing is needed, then that thing is sufficient.

So if only one more thunderstorm is needed to ruin the roof, a thunderstorm is sufficient to ruin the roof.

If we see a thunderstorm coming, we can be certain that the roof will be ruined. However, according to the same statement, if we see that the roof is ruined, we cannot be certain that it was a thunderstorm that did it!

Does that help you put this into notation?

[LSAT-Chang]

The word "needed" definitely confused me too.
Is the key "If only one thing is needed"???
Because if we had something like "A new haircut is needed to go to the party tomorrow" we would have:

party tomorrow --> new haircut

since you can't go to the party tomorrow if you didn't get a new haircut. so if you went to the party, then you must have had the new haircut.

Would you agree???

[ManhattanPrepLSAT1]

Another great question! Nice So, that's paying attention to detail. This issue here is that "all that would be needed" to make money disappear is a universal loss in belief in it. If only one thing is needed, somehow, it magically becomes sufficient!

All that is needed
Only one more is needed
Depends only on one thing
Needs only one more

Sometimes you can here the idea of double-necessity. When you here multiple terms implying necessity or you can see that only one more thing is needed for something to occur, then the term that represents the last thing needed, is actually sufficient.

Weird huh?

[zainrizvi]

The best way to think about "even if" is to ignore it!

So, for example...

Even if the fog roles in, the boat will sail.

You would NOT diagram this

FR --> BS

Instead, it merely says

BS

This is not a conditional statement, but rather a a statement of fact. So, you ignore the even if part, and state that the other part will happen regardless.

Let me know if this needs further elaboration. This can be tricky.

I am really, really confused by this because I don't see how you could diagram the answer choice then - it wouldn't show any relationship. It would just be "money exists" as a sufficient condition...

[spfelker]

Can someone dumb down the reason why "A" is correct and explain why "D" is incorrect? Much appreciated.

[tswiftforever]

I am still really confused by why (A) is correct.

When working on this question, I immediately eliminated (A) on the first go-around because I thought it was the completely opposite of what the conclusion was arguing.

The conclusion in the argument is that money doesn't really exist, and the supporting premises are: All that would be needed to make money disappear would be a universal loss of belief in it, even though money seems to have importance in our lives.

So how is (A) correct? I looked at the commentary above but it didn't help me understand why (A) is right and is not saying the opposite of what the argument is saying..

[ohthatpatrick]

As you said:
"The conclusion in the argument is that money doesn't really exist, and the supporting premises are: All that would be needed to make money disappear would be a universal loss of belief in it, even though money seems to have importance in our lives."

(The 'even though' part is not a premise. It's an opposing point. Anything prefaced by 'despite, although, while, even though' is going to be opposing the other half of the sentence it's in)

Since this is sufficient assumption, we don't have to go too deep into the conversational topic. We just need a mechanical "PREM->CONC" link.

So here we need,

IF
all you need to make money disappear is a universal loss of belief in it
THEN
money does not really exist.

So we know what a correct answer should sound like. Remember, though, that a common tendency on Sufficient Assumption is to write the answer as the contrapositive of what we were initially predicting.

Let's take a sec to say the contrapositive of what we just wrote.

IF
money DOES really exist
THEN
a universal loss of belief in it would NOT make it disappear

(A) gives us this rule
"a universal loss of belief" = "everyone were to stop believing in it"
"would NOT make it disappear" = "would continue to exist"

You could ask yourself, "Would money continue to exist even if everyone were to stop believing in it?" and you should answer, "No. The premise told me that a universal loss of belief in money would make it disappear." Well, when you're reading a conditional statement, if the second idea doesn't apply then the first one can't either. So we could think to ourselves, "Oh, well then according to this rule, money does NOT exist."

Your sentiment that (A) sounds like the opposite of the argument is coming from the fact that when we write a contrapositive we use the negated (opposite) form of the ideas from the argument.

For example, if I argued:
Bob is left handed.
Thus, Bob is clumsy.

Then a sufficient assumption could sound like:
"Anyone who is not clumsy is not left handed".

It sounds like I'm saying the opposite of the ideas we talked about, but the contrapositive of that rule is

Left-handed -> Clumsy

So be very aware of this tendency and realize that LSAT does it purposefully to disguise the right idea. When assessing conditional statements in answer choices, it's important to consider their contrapositives, because doing so might make us see why that answer actually works.

Hope this helps.

#officialexplanation

[levyyun]

I've read through the explanations, and I have to say that I am more confused than ever. I tried my best to understand all the conditional logic and analogy explanations, but they just made me want to abandon this question and move on.

The main problem I am having is that I still don't understand what exactly I'm looking for/what the problem is with the argument.

And what does it mean by "...does not really exist"? Are we talking about money not being tangible or the fact that it does not have any value? Does it really make a difference which definition I choose?

Answer choice A (to me at least) just seems to be the total opposite of the premise.

Hopefully someone can help me out.

Thanks.

[christine.defenbaugh]

I've read through the explanations, and I have to say that I am more confused than ever. I tried my best to understand all the conditional logic and analogy explanations, but they just made me want to abandon this question and move on.

The main problem I am having is that I still don't understand what exactly I'm looking for/what the problem is with the argument.

And what does it mean by "...does not really exist"? Are we talking about money not being tangible or the fact that it does not have any value? Does it really make a difference which definition I choose?

Answer choice A (to me at least) just seems to be the total opposite of the premise.

Hopefully someone can help me out.

Thanks.

Thanks for posting, levyyun!

This is certainly a doozy of a question, questioning the very existence of things in our lives! Talk about some philosophical labyrinths!

Let's return back to the essential core of the argument:

PREMISE: If we stop believing in money, money would disappear
CONCLUSION: Money does not really exist.

First, what does it mean for money to "disappear"? It doesn't really matter here how you define "disappear", as long as it's the same as "does not exist". The author is actually making an argument about the existence of money as a concept, so the tangibility of physical currency isn't really on the table, but you don't really need to sort this out to answer the question.

So, the author is saying in the premise that if we did a certain thing [stopped believe in money], then a certain result would happen [money would stop existing at that point]. He concludes from that that money does exist at all, even now. Somehow, he is using the potential for money to stop existing in the future as evidence that it can't exist now. Just that characteristic of money is somehow enough to kick it out of the club of things that exist.

Now, let's take your observation that there's something about (A) that feels opposite to the premise. And to a certain extent, you're right! The answer choice is all about something continuing to exist, despite our lack of faith! And the premise said that money would STOP existing if we lost faith! Very opposite results!

But notice, the premise is about what happens to money, and how it will stop existing. Answer choice (A) is about things that exist, and how they behave.

So, if we take the premise and (A) together, what we have is that money and things that exist behave completely differently! That would allow us to conclude that money must not be a thing that exists! That potential for it to stop existing in the future is now truly enough for us to conclude that it is not in the category of things that exist!

This is a tough question, in no small part because it's easy to get wrapped up in the actual philosophical question about the existence of things! It's best to resist that temptation, and continue to look at this argument core in the same way we look at every argument core: identify conclusion, identify premise, identify the gap between!

I hope this helps to clear up some confusion on a sticky question!

[tangdanni422]

I got this question wrong during my PT, but I can see now why A is the correct answer thanks to the great discussions here.

This is what I think:

The author concludes that money does not exist because a universal loss of belief would make money disappear. So the author is assuming this:

(LB->D) -> ~E

by contrapositive, it is:

E -> ~(LB->D)

This means that if money exists then a universal loss of belief would not make the money disappear.

Here we are looking for a sufficient assumption, so the correct answer can address things in general, not necessarily limited to the money specifically.

Let's look at A:

Anything that exists would continue to exist even if everyone were to stop believing it. What does this mean? It actually means anything that exists would not disappear even if there is a universal loss of belief (note if something disappears then that thing would not continue to exist):

E -> ~(LB -> D)

by contrapositive, it means: if a universal loss of belief can make something disappear, then that thing does not exist:

(LB->D) -> ~E

It is the assumption we are looking for in a bigger scope.

---

Additionally I have two questions for Manhattan instructors:

The first question is:

Can we say the author here is assuming that if money disappears then the money does not exist? This is to say, is the author assuming D->~E?

I am inclined to say the author does not make this assumption because there could be other things to make the money disappear and the author is only to say that if specifically a universal loss of belief leads to the disappear of money, then the money does not exist.

The second question is:

For "E -> ~(LB->D)"

Does it mean "if money exists then a universal loss of belief would NOT make the money disappear" or "if money exists then a universal loss of belief would NOT NECESSARILY/ALWAYS make the money disappear?"

Thanks in advance:)

[christine.defenbaugh]

We know that
(~B -> D) -> ~E
So we know that
~B -> ( D -> ~E)
Then we can conclude that
~B -> ( E -> ~D) this is what answer (A) is saying.

This is a very difficult formal logic question.

Hey nju.guyan!

I think I understand what you're doing here, and it's fundamentally correct. However, I would caution you that sometimes, such extraordinarily abstraction/formalization can be a bit of a rabbit hole.

Also, be really careful about that last step: "~B -> ( E -> ~D)" isn't exactly what (A) is saying. Rather, (A) is a much broader statement. That's okay though, because we just need something sufficient to make it work, and overkill is a-okay.

Take a step back, and notice how we should be able to eliminate the wrong answers, if we have a good understanding of the essential core (even without substantial formalization!):

(B) This conditional is "if exist --> mistaken beliefs possible". "Mistaken beliefs" are out of scope.
(C) This conditional is "If exist --> practical consequences". "Practical consequences" are out of scope.
(D) This conditional is "if believe --> exist". Our conclusion is that something DOESN'T exist. A conditional that results in guaranteed 'existence' will never help me!
(E) "Financial markets generally" isn't actually part of the argument core. Answer also doesn't touch on "existence."

Also, tangdanni422's breakdown is a bit older, but I just had to comment on how SUPER AWESOME it was! Go tangdanni422!

Additionally I have two questions for Manhattan instructors:

The first question is:
Can we say the author here is assuming that if money disappears then the money does not exist? This is to say, is the author assuming D->~E?

I am inclined to say the author does not make this assumption because there could be other things to make the money disappear and the author is only to say that if specifically a universal loss of belief leads to the disappear of money, then the money does not exist.

Exactly right! Aliens could make Stonehenge 'disappear', and that doesn't prove that Stonehenge 'doesn't exist'. The author is only assuming that money's disappearing because of our lack of belief proves non-existence.

The second question is:

For "E -> ~(LB->D)"

Does it mean "if money exists then a universal loss of belief would NOT make the money disappear" or "if money exists then a universal loss of belief would NOT NECESSARILY/ALWAYS make the money disappear?"

AWESOME question. "~(LB-->D)" is the same thing as saying "that rule I mentioned? Yeah, it's not actually a rule." Negating a conditional is just saying that the rule doesn't exist.

So, with no rule to guide us, a universal loss of belief would not necessarily/always make the thing disappear. The loss of belief doesn't, itself, guarantee existence. It just doesn't necessarily destroy it.

Great work on a super tough question!

[dhlim3]

Take a step back, and notice how we should be able to eliminate the wrong answers, if we have a good understanding of the essential core (even without substantial formalization!):

(B) This conditional is "if exist --> mistaken beliefs possible". "Mistaken beliefs" are out of scope.
(C) This conditional is "If exist --> practical consequences". "Practical consequences" are out of scope.
(D) This conditional is "if believe --> exist". Our conclusion is that something DOESN'T exist. A conditional that results in guaranteed 'existence' will never help me!
(E) "Financial markets generally" isn't actually part of the argument core. Answer also doesn't touch on "existence."

Maybe I'm the only idiot here that picked E ("Whatever is true of money is true of financial markets generally.").

I thought E was definitely part of the core and the argument centered around how the behavior of the financial market is analogous to the behavior of money.

How I read the argument:

PREMISE 1: All that would be needed to make money disappear would be a universal loss of belief in it.
PREMISE 2: Fluctuations in financial markets are the results of mere beliefs of investors.
---------------------------------------------------------------------------------------------------------------------------------------------------
CONCLUSION: Money does not exist.

I understand that Premise 2 does not mention anything about the existence explicitly, but I understood it as since extreme downward fluctuation can eventually lead to the "disappearance of its value", I somehow thought it was relevant to the discussion of existence. Is this a stretch?

Also, if I'm wrong about categorizing the last sentence about the financial markets as premise, what is the proper role that it plays? Intermediary conclusion? Or is it a premise that supports PREMISE 1 (which in turn would actually make PREMISE 1 an intermediary conclusion)?

I can kind of see why E is wrong, not because it is out of scope but because it has the relationship reversed (It's saying: Money -> Financial Market, but the argument actually assumes Financial Market -> Money). If the answer choice E instead had said, "Whatever is true of financial markets generally is true of money", could this have been a valid answer?

[jennifertrimo]

Are the contrapostives correct only for sufficient assumption questions or for necessary assumptions as well?

[stephaniexen]

Premise 1: "the fact that all that would be needed to make money disappear would be a universal loss of believe in it."

universal loss of belief --> money disappears

Premise 2: "fluctuations are the result of mere beliefs of investors"

investors' beliefs --> fluctuations (i.e. money disappears and comes back)

From the two premises:

universal loss of belief --> money disappears
investors' beliefs --> money disappears

We can say: Regardless of people's beliefs, money disappears. If everyone loses belief (universal loss of belief), it disappears. If they do believe (like investors), it fluctuates, temporarily disappearing. Thus, we can accept "Money disappears" as a fact:

A --> B
Not A --> B
-----------
Thus: B

Now the editorialist's conclusion is: Money does not exist.

So the sufficient assumption the stem requests is:

money disappears --> money does not exist

Notice, this leads to the contrapositive:

money exists --> money does not disappear

To reiterate, in plain English: If money exists, then money doesn't disappear, even if people do not believe it.

Compare answer A: "Anything that exists would continue to exist even if everyone were to step believing in it."

This answer sufficiently guarantees the arguments validity (since "anything" would obviously include money.)

The key here is the phrase "even if". "A even if B" means "A regardless of B" or "A whether or not B". This reiterates our inference above: (A --> B) and (Not A --> B), thus B.