Q15 - Ordinary mountain sickness, a common

[jenndg100380]

Can someone please walk me through this? I was able to cross off B, D, and E, but I had a hard time between A and C. Even after looking up the answer, I was still left scratching my head. The argument seemed to be focused on the similarity between the symptoms not the treatment...

[ManhattanPrepLSAT1]

The best way to proceed when you're down to answer choices (A) and (C) like this is to apply the negation test. This is a necessary assumption question, so the the assumption is needed for the conclusion to be true. Without the assumption the conclusion would be undermined.

So negate the answer choices one-by-one and when you negate the correct answer that should destroy the conclusion. So let's keep track of what the conclusion is. The argument concludes that cerebral edema is especially dangerous at high altitudes.

Negate answer choice (A)
The treatment for ordinary mountain sickness does not differ from the treatment for cerebral edema.

Well if the treatment is the same, then cerebral edema is not especially dangerous at high altitudes because if the climbers treated for ordinary mountain sickness instead of cerebral edema, the climbers would still be treating the cerebral edema - the treatments would be the same.

Negate answer choice (C)
Ordinary mountain sickness involves some disruption of blood circulation in the brain.

Even if this were true, cerebral edema could still be especially dangerous at high altitudes. The answer choice is not about cerebral edema in any way, and so doesn't challenge the conclusion in any way. Thus answer choice (C) is not correct.

Let me know if that helps clear this up. If not, I'd be happy to keep working on it with you.

[greatwhiteshark100]

I still don't get it though.

If most of the time climbers do not react to the symptoms, then whether or not the treatments are the same does not matter. The danger would lie in whether or not they mostly received treatment to recover or not, since if most recovered on their own, then they might be led into thinking they were having normal mountain sickness when they would actually be having cerebral edema, that would be the danger!

[ManhattanPrepLSAT1]

Not necessarily. Suppose the treat for ordinary mountain sickness was identical to the treatment for cerebral edema. Then cerebral edema would not be particularly dangerous. In fact, distinguishing between the two illnesses wouldn't even be necessary, because the treatment would be the same either way.

The conclusion of the argument is that cerebral edema would be particularly dangerous, but we just showed that if the treatments for the two illnesses were the same then the cerebral edema would not be particularly dangerous. Thus, the negation of answer choice (A) would destroy the conclusion.

If an answer choice represents a necessary assumption of the argument, then without it, the conclusion cannot stand. By negating answer choice (A) we can see that the answer choice was necessary to the argument.

Let me know if you see things differently!

[LSAT-Chang]

Hey Matt,
It seems like you explained this problem just in terms of the conclusion.
How about the premise?
When I first read this, I noticed it was a necessary assumption question, so like with all assumption family ques, I looked for the core. The core I found was:

symptoms of cerebral edema resemble those of ordinary mountain sickness therefore cerebal edema is especially dangerous at high altitudes.

So the "gap" I thought was something like if symptoms of cerebral edema resemble those of ordinary mountain sickess then cerebral edema is especially dangerous at high altitudes. So I thought there was something going on about "symptoms" and being dangerous at high altitudes. So I just jumped on the answers since I didn't quite get what the author was assuming (though I understand that there are numerous necessary assumptions for an argument so it is unlikely that I will be able to prephrase the correct one).

So when I read (A), I crossed it out immediately since there was nothing about "treatments" in the premise or the conclusion. I thought the purpose of finding the right core was so that we don't spend time with answer choices that talk about stuff not related to the actual core -- to me, the word "treatment" didn't relate at all since we are talking about symptoms and something being dangerous at high altitudes.

I didn't like any of the answer choices so I just left this blank..

[ManhattanPrepLSAT1]

Thanks for the question. I agree that it's important to find the argument core. My earlier explanation was geared towards identifying the correct answer between answer choices (A) and (C). The fact that the symptoms are so similar is what makes it hard to distinguish ordinary mountain sickness from cerebral edema. What makes this so dangerous? Well if you can't tell them apart and you need one treatment for cerebral edema and another for ordinary mountain sickness, getting the wrong treatment could be devastating.

On Necessary Assumption questions, frequently the correct answer will take the form of protecting the argument from something that would be devastating to the argument's reasoning. So in order to conclude that cerebral edema is dangerous when you cannot distinguish it from ordinary mountain sickness it would need to be the case that the treatment required for cerebral edema is different than for ordinary mountain sickness. Otherwise why would cerebral edema be so dangerous?

When you see that the argument needs to be defended from something completely undermining, you'll find that frequently the answer will sound "out of left field" though on this one I think that a discussion of treatments doesn't seem that far off given that the argument is about the danger posed by several ailments.

Hope that helps!

[LSAT-Chang]

Thanks for the great explanation!

[mistermortensen]

Great explanation but I have to agree that Vinny seems right.

A) is the correct answer because it is the best answer available. But I believe that it is logically incorrect since the assumption cited is not one the argument depends on.

As advised, I negated the assumption in answer choice A:

"The treatment for ordinary mountain sickness does not differ from the treatment for cerebral edema."

Even in light of the negated assumption, I would argue that the conclusion stands. "Although the treatment for ordinary mountain sickness and the treatment for cerebral edema do not differ, it is because the symptoms of cerebral edema resemble those of ordinary mountain sickness that cerebral edema is especially dangerous at high altitudes."

In this case how would cerebral edema be especially dangerous at high altitudes? Because a misdiagnosis is possible. In this scenario, mountain sickness exhibits symptoms that resemble cerebral edema. And cerebral edema shares a causative factor with ordinary mountain sickness -- a shortage of oxygen. Thus, at high altitudes, one could potentially misdiagnose ordinary mountain sickness when the underlying condition is cerebral edema. (<---This is an assumption the argument depends on.) Okay, but why does this make cerebral edema especially dangerous at high altitudes? Because a misdiagnosis of one condition for another could be fatal -- yes, even if treatment for both is the same. The fact that cerebral edema "quickly becomes life-threatening if not correctly treated from its onset," is not a negligible factor. In fact, a reasonable person could assume that this indicates a critical emergency, necessitating a full medical response. Regardless of the specific treatment for cerebral edema, the rapid progression and the need for correct treatment would require immediate attention, medical professional(s), the highest quality care available, rapid transport, any extra available resources (i.e. medical evacuation) and maximum expenditure of collective effort to ensure a positive outcome. It seems quite logical that in addition to specific treatment there are many crucial factors involved:

1. The expediency of the treatment.
2. The quality of the care.
3. The extent of the response.

It is probably not unintentional that in the real world these two conditions typically do have similar symptoms and also share similar medical treatments. If a mountain climber suspected another climber to be suffering from "acute mountain sickness" a proper treatment would be to "descend to a lower elevation where there is more oxygen in the atmosphere." This treatment is the same as it is for "high-altitude cerebral edema." However, in the latter situation you would not allow the patient to walk/climb/hike under his/her own volition as this might increase oxygen demand and exacerbate the condition. Furthermore, because the latter is a serious emergency with a rapid, sometimes irreversible onset if there was a doctor at base camp or a helicopter with a medical team you would radio for their immediate assistance. Additionally, if a qualified individual had high flow oxygen, dexamethasone (a corticosteroid) or a Gamow® Bag (portable hyperbaric chamber) rescuers would probably do whatever they could to get them to the patient. Incidentally, these listed treatments for high altitude cerebral edema do not necessarily differ from those listed for acute mountain sickness (and vice versa check out this High Altitude Medical Guide for reference: http://www.high-altitude-medicine.com/A ... .html#HACE). But because high altitude cerebral edema is greater in degree of severity and rate of onset it is rightfully managed with a drastically different approach. Again, the treatment for both is nearly identical.

Of course, I'm not a doctor and LSAC doesn't expect me to be one. I was just throwing down some specifics to bring home my point. If you're gonna claim the LSAT has a less than accurate "correct" answer choice, you better back it up.

Ultimately, I believe the answer to this question is incorrect based on the fact that the author distinguishes cerebral edema as quickly becoming life-threatening if not correctly treated from its onset. Furthermore, the names of the conditions are secondary to the logic involved. The stimulus could describe a bee sting versus anaphylactic shock in a remote wilderness. Or perhaps heat exhaustion versus heat stroke on a boat floating in the ocean.

In all of these scenarios, a proper initial diagnosis is crucial even if the treatment for both does not differ. Regarding medical conditions, the severity of consequences, the rate of onset and the likelihood of survival affects the way we manage an incident. Anyone who has ever had to decide whether to call 9-1-1 or not has encountered such choices.

Finally, I could see how the answer choice provided is in fact both logical and correct. One would have to assume that ordinary mountain sickness is at least an equal medical emergency compared to cerebral edema and that it too, "quickly becomes life-threatening if not correctly treated from its onset." Even though it is described as a common condition among mountain climbers and one from which most people can recover, this is a possible scenario. However, this exaggerated reasoning seems to contradict a a college level knowledge of reality. To me, it would be like equating "ordinary flu sickness" to myocardial infarction (a.k.a heart attack). The fact that one is described as quickly becoming life-threatening and the other is not seems to distinguish the two. If it doesn't then we are expected to make a stretch in reasoning that LSAC typically tends to avoid.

Perhaps I am missing something obvious. Maybe the treatment for ordinary mountain sickness/cerebral edema" really means "the treatment of ordinary mountain sickness/cerebral edema." If this is the case then the answer choice may not be referring to a specific medical intervention, but only the general manner a normal person would react to the situation. However, this seems like an incorrect use of common language.

Thanks,

[irene122]

I narrow down to A and E. I choose A because negating it would hurt the argument, but I am not sure how to negate E.
I diagram E as follows:
most people: recover--> no special treatment
(I understand with the restriction of "most", the sentence does not contain a conditional reasoning situation.)

Which one of the following should be the correct negation of E?
1. most people who suffer from...recover with special treatment. (negating the "without" part)
2. not most people who suffer from...recover without any special treatment. (negating the "most" part)

Thanks a lot!

[ManhattanPrepLSAT1]

This one is tricky, so I can see why this one gave you pause for thought!

The negation of a quantification is pretty straightforward:

None ---> Some
Some ---> None
Most ---> Half or less
All ---> Not all

A short cut on negating "Most," would be "Most are not."

In this case it's a bit trickier, but you're correct to negate the quantification of "most." The short cut would be:

Most people who suffer from ordinary mountain sickness do not recover without any special treatment. Or in other words... most people who suffer from ordinary mountain sickness need special treatment in order to recover.

The more precise negation would be something like... half or more people who suffer from ordinary mountain sickness need special treatment in order to recover.

Does that answer your question?

[irene122]

This one is tricky, so I can see why this one gave you pause for thought!

The negation of a quantification is pretty straightforward:

None ---> Some
Some ---> None
Most ---> Half or less
All ---> Not all

A short cut on negating "Most," would be "Most are not."

In this case it's a bit trickier, but you're correct to negate the quantification of "most." The short cut would be:

Most people who suffer from ordinary mountain sickness do not recover without any special treatment. Or in other words... most people who suffer from ordinary mountain sickness need special treatment in order to recover.

The more precise negation would be something like... half or more people who suffer from ordinary mountain sickness need special treatment in order to recover.

Does that answer your question?

Sorry but I am still confused. I understand negating "most" would be "most are not"; negating "all" would be "not all"; but I am confused where to put the "not":

eg. "most people suffer from...recover without any special treatment"
after negation, should it be:

"not most people suffer from ordinary mountain sickness recover without any special treatment" (not most)

or

"most people suffer from ordinary mountain sickness recover with speical treatment" (most are not) ?

Thank you!

[ManhattanPrepLSAT1]

The second option that you've got there is the correct way to negate the statement.

"most people suffer from ordinary mountain sickness recover with speical treatment" (most are not) ?

Important question, glad you asked.

[irene122]

Thanks a lot! really clear up the negation!

[sumukh09]

Wouldn't accepting A as the correct answer require us to make the additional assumption that the treatment is the same regardless if exacerbated by high altitudes? Cerebral edema is especially dangerous at high altitudes, so why is it that we have to assume that its effect at high altitudes is not altered to the extent that the treatment would not work?

To further clarify my question, cerebral edema and ordinary mountain sickness are similar enough that the treatment is the same, but what about when the two are taken together, as is described in the stimulus, how do we know the treatment is still as effective?

Thanks in advance.

[maryadkins]

Not sure I follow your question, but let me take a stab at clarifying.

First, the claim that CE is "especially dangerous" at high altitudes is what's being argued. We don't take it as given.

What does especially mean?

That it's even more dangerous than usual, basically. It's REALLY dangerous.

If we negate (A)"”which is how we deal with necessary assumptions (and if this isn't ringing a bell, definitely read up on necessary versus sufficient assumptions)"”we get, "The treatment for ordinary mountain sickness does not differ from the treatment for cerebral edema."

That means we're not assuming anything about the treatment being the same in choosing it. We're choosing it because if it weren't true, the negation of the statement tells us that the argument would fall apart

Getting into hypotheticals about how higher altitudes might alter whether or not the treatment is the same brings in ideas that we don't need to worry about.

On a necessary assumption question your job is to negate the answer choice. If the argument crumbles under that new truth, it's your answer. Don't make it more complicated than it needs to be!

[WaltGrace1983]

This is not my favorite one in the book because the gap is not very obvious...at all. However, I do believe that (B) through (E) are no good and here is why: they are very obviously NOT necessary.

(B) This doesn't show why cerebral edema is *especially* dangerous at high altitudes. In addition, do we really need to assume anything about the length of time in which a person with cerebral edema will fall into a coma? Would it make a difference if they fell into a coma within a few minutes? (B) is not necessary.

(C) This is talking about ordinary mountain sickness which doesn't seem to help us in our quest of proving/disproving that cerebral edema is especially dangerous at high altitudes. Also, do we have to assume that OMS involves no disruption of blood circulation? What if disrupts blood circulation just a little bit? Does that change things? No. (C) is not necessary.

(D) What if it doesn't do either but is dangerous for other reasons? This also doesn't seem to prove anything about cerebral edema specifically. (D) is not necessary.

(E) What if "most" people need the treatment? Does it make/break the argument that people with cerebral edema (notice that E is talking about OMS) is *especially* dangerous?

I will say that (D) definitely seems to strengthen the argument and (B) seems to also, though to a much lesser extent because it doesn't talk specifically about high altitudes.

However, our job is to find something that is necessary and if we misunderstand our task, we can fall victim to a B or a D. Otherwise, when we fully understand our task, (A) is clearly the best answer - though definitely not the most obvious.

[erikrynko]

#29 Section 1, Q. 15.
MisterMortensen is the only one on the right track to why this question is faulty. The Official Answer is A, but A is deficient.


First let's discuss the question stem's meaning.

The question stem is asking for an assumption for which the argument depends. This can be rephrased as: If this assumption were not true, the argument would not be valid, OR this assumption MUST BE TRUE for the argument to be logically sound.
This is different from a justify question, which asks for an answer that will completely link the premise to a conclusion, so the logic in the argument is now airtight. This question is only asking for one of the several assumptions for which the argument depends.
I offer several examples and analysis of assumptions for which this question’s argument actually depends, at the end of this article.

Although this is not a justify question, it is also not a strengthen question. It doesn’t matter if the argument is strengthened by the assumption, it only matters if the argument cannot be logically sound if the assumption were false. An argument depends on an assumption if that assumption is a critical part of the foundation of the argument, and the argument would collapse without it.
Therefore, any answer choice that only strengthens the argument, but does not invalidate the argument if the assumption were false, is incorrect.

Analysis of answer choices:

A) The answer suggests that the treatments for OMS and CE must be different, implying that if they were the same, then CE would not be especially dangerous because it mimics the symptoms of OMS. People with CE that were treated for OMS would coincidentally be receiving the correct treatment for CE. However, although this is the official answer, it is still FALSE.
Although this assumption strengthens the argument, as some people would most likely coincidentally receive the correct treatment for CE, the fact that the author stresses that CE needs to be “treated from its onset” makes this assumption not necessarily true. The treatment could be the same, but the importance of treating CE immediately could be the factor that makes CE especially dangerous when confused with OMS.
If the treatment for OMS and CE is a backrub, some climbers may not want to stop immediately to administer treatment upon onset of symptoms if most people with OMS would recover if they receive treatment up to several hours after symptoms emerge. Perhaps the climbers will wait until they get to a safer location to being treatment. However, if the climbers accurately diagnosed the ailment as CE, then they would immediately administer the backrub, because immediate treatment is required to prevent possible life-threatening consequences.
This example reveals how the treatments for OMS and CE do not have to be different for CE to be especially dangerous because of the possibility that CE might be misdiagnosed as OMS. Since the argument does not depend on this assumption being true, then this answer is incorrect.

B) This answer is incorrect. It doesn’t matter that people with CE could slip into a coma into a few hours. It only matters that people with CE receive the appropriate treatment at the onset of the symptoms. If people with CE did not slip into comas in a few hours, the argument would not be weakened.

C) Incorrect. Doesn’t matter how the ailments affect the brain. It only matters how dangerous the conditions are, and if they can be treated. If OMS did involve disruption of blood to the brain, it wouldn’t weaken the argument. The argument states that that most people recover from OMS, and how OMS affects the body is irrelevant.

D) Incorrect. Also, outside of the scope of the argument. It doesn’t inherently matter that decision-making is impaired. The argument would be unaffected by the opposite statement, that decision-making is unimpaired at high altitudes.

E) This answer is also incorrect, but it does strengthen the argument, similar to answer choice A. The stimulus states that CE must be treated at onset, which is another way of saying, that there is a treatment for CE. If the treatment was to do nothing, then CE wouldn’t be inherently dangerous, and there wouldn’t be a stipulation that CE must be treated at its onset. To assume that most people recover with no special treatment required for OMS, would suggest that most people may not be treated for OMS. This would assure that some people with CE that are misdiagnosed with OMS would not receive any treatment, which could be life-threatening.

There is no correct answer. Although answers A and E legitimately strengthen the argument, that is not what the question stem is asking for.


Examples of other assumptions on which this argument depends:

1. At least some people have the ability to treat Cerebral Edema at high altitudes or act in a way that could limit the life-threatening danger.
2. The resemblance of symptoms between OMS and Cerebral Edema (CE) is significant enough for at least some people to render a misdiagnosis.
3. Other traits of high altitude conditions, such as lower pressure, does not prevent CE from occurring.
4. Other traits of high altitude conditions do not alter the manifestation of the symptoms of CE that make them noticeably different than the symptoms for OMS.
5. And many more.

If any of those assumptions were not true, the argument would be flawed in some way. Therefore, the argument DEPENDS on those assumptions.

Here’s why:

1. The last line of the stimulus conclusion, which states that CE is especially dangerous at high altitudes because the symptoms resemble the symptoms of OMS. If no one is able to treat CE at high altitudes, or mitigate the danger by taking some course of action, then it wouldn’t matter that the symptoms are similar. Sure, CE may still be more dangerous the OMS, but it wouldn’t matter in the author’s argument.
2. If the symptoms for OMS and CE “resemble” each other, but not by enough for anyone to render a misdiagnosis under any conditions, then the resemblance doesn’t matter. This invalidates the argument’s conclusion that CE is especially dangerous because the symptoms are similar.
3. The author only describes CE as being caused by low oxygen conditions, but perhaps other conditions of high altitude prevent CE from occurring. Therefore, no one would get CE in high altitudes, and people can correctly assume the person with symptoms has OMS
4. The author only says the symptoms of CE and OMS are similar, but doesn’t mention if high altitude conditions could alter the manifestation of those symptoms. Since the conclusion is referring to specifically to conditions at high altitudes, if the symptoms of CE are altered under those conditions, to be noticeably different than the symptoms of OMS, the argument would be invalidated.
5. There are many more assumptions.

The point is, that there are several assumptions that MUST BE TRUE for the argument to be logically sound.

However, there is no valid answer that appears in the answers for this question.

You could attempt to pick the “best” answer, but both answers A and E strengthen the argument. However, they are still technically just as incorrect as B, C, and D.

[natalie.seni]

First off, I agree with mistermortensen above.

I had some trouble with this question and although I've read the above explanations, I'm unable to see how A is correct.

In a NA question, we're looking for an assumption that's necessary for the argument to hold up - without it, the entire argument would crumble. One method to determine this is the negation test.

The author is arguing that CE is especially dangerous at high altitudes on the grounds that its symptoms resemble the symptoms of OMS.

If I negate A I get, "The treatment for OMS does NOT differ from the treatment for cerebral edema". I am having trouble figuring out how same treatments impacts whether or not something is especially dangerous...can someone please help me understand why this destroys the argument and why A is necessary for the argument to stand?

[maryadkins]

Think about it this way.

If I say, it's especially dangerous to feel thirsty in the desert, because feeling thirsty can be mixed up with dehydration, which is very serious in the desert. You might think you're just feeling thirsty but really, you're dehydrated—bigger deal.

But why would this matter if the way to "treat" either situation is the same thing: to drink water? Then, the fact that they could be mixed up doesn't really matter, because either way, you should just drink water.

That's what is happening here. If the treatment for them is the same, as it would be if we negated (A) which you note, that means the fact that they could be mixed up doesn't matter, or in other words, it's not "especially" dangerous, as the conclusion states. The argument falls apart.

I hope this helps clarify.

[esthertan0310]

I see it this way

The context is "at high altitude"

The symptoms of CE and ordinary mountain sickness are similar. When those symptoms occur at high altitude, people can easily mistake CE for ordinary mountain sickness. Then the author mentions "CE is very dangerous at high altitude". We need to find out why the author thinks that "CE, which is mistaken for ordinary mountain sickness, is very dangerous".

Option (A) fills the gap perfectly: because, at high altitude, chances are CE will be treated as ordinary mountain sickness, while actually, CE takes special/different treatment.