Scientist: Cross-sections of stalactites-calcite formations deposited

I was very torn between B and D. Can you please explain why it is not B? I understand this premise attacks the facts stated; however, his hypothesis is founded on that premise and thus the hypothesis is very weak if it is founded on a premise that you cannot found a premise on (per choice B; all the support for his hypothesis is gone in an instant with B)...

To me, D you *must* assume (code red never to do on CR) that there isn't food left over because the dictators/leaders etc. kept it all to themselves. Thus, their society collapsed around them. Or some other plausible explanation. The hypothesis is based on a drought weakening agricultural output. B says, objectively (no possible fringe scenario I can think of), that using XSection alone is insufficient to draw any conclusion about agricultural output.

Thank you.

Vyshak,

Option B is not attacking any fact. "I hipothesize that drought reduced agricultural productivity..." is not a fact. It is rather an inference that the author makes based on the fact that there was a drought. The author then draws a conclusion based on this inference, which plays the role of a premise in his hypothesis/argument.

We can weaken the author's hypothesis by either attacking his premise or his conclusion. Option B weakens his premise, while option D weakens his conclusion.

Can anyone please explain the reason why we should discard option B?

The conclusion is that drought reduces agricultural productivity, thereby causing collapse of society. The weakening statement should attack the link between drought and collapse of society. However option B links information from stalactites and drought - it does not address the link between drought and collapse. Hence B is not a weakening statement.

A. Many droughts indicated in the cross-sections of stalactites do not correspond with the collapse of a society in that area.
It is ,"often" in the passage, so the argument doesn't exclude other potential causes.
B. Information from the cross-sections of stalactites alone cannot reveal the level of agricultural output in an area at a particular time.
Hypothesis is about adequate availability of goods to sustain society well-being.
C. Most of the societies that collapsed during droughts did so when internal power struggles coincided with military raids from neighboring societies.
Strengthen.
D. Most of the societies that collapsed during droughts maintained large stockpiles of food and water at the time of their collapse.
This statement doesn't go in line with scientists' hypothesis as despite the availability of goods societies collapsed, thus any other reason caused societies stop existing.
E. Information from stalactites also suggests that the collapse of some societies coincided with periods of abnormally high rainfall.
Abnormally high water could have resulted in crops loss and thereby society crush.

Answer D.

Can anyone please explain why C cannot be an answer choice?

C states that the societies collapsed because of reasons other than lack of resources.

Let me try to help you. As mentioned above your conclusion is : thereby leaving these societies without the resources needed to handle internal stresses and external threats. To elaborate on that it is trying to make a point that if there will not less/no agriculture, there will be no/less resources needed to handle internal stresses and external threats.

choice C is not talking about resources. think it more like this way. suppose they have a lot of food to fill everyone for whole season, but due to internal power struggles coincided with military raids from neighboring societies, they perished. is it seems a right idea.

Hope it helped. ask specific question if any.

I am confused with how this question is written. The question asks for the the weaking of the "support" for the hypothesis, rather than the hypothesis itself. Therefore, to address the question, shouldn't we be looking at the answer choice that attacks the support portion of the argument?

The hypothesis is: drought -> agricultural insufficiency -> downfall of societies
The support for the hypothesis: cross-section analysis of stalactites indicates there are droughts

Therefore, to attack the SUPPORT, a possible weakener could be that the pattern between stalacities and droughts is not actually established

Why is this logic wrong?

lyfan512
For questions like this, it's important to recognize the underlying ground rules. Regardless of the question, we never question the premises (the stated facts) of the argument. Rather, we look for the disconnect between these premises and the stated conclusion. If we want to weaken a conclusion, we knock down its support not by denying the premises, but by showing how the premises may not lead to the conclusion as stated. I agree that this question is worded more confusingly than usual, but that is still our task. If the premises don't lead to the conclusion, then the conclusion lacks support!

Here, the argument is using a correlation (droughts, collapse) to attempt to make a very specific causal claim: it's not just that droughts cause collapse, but they cause it by leaving societies without the needed resources. That's where D fits in. If these societies had plenty of resources stockpiled at the time of collapse, then it's not at all clear that drought had this particular effect. So while the premise may still be true, it doesn't clearly support the conclusion the author wants. That's the only sense in which we have "weakened the support."

Another important point is that even if we did want to weaken a premise, answer choice A doesn't do that. In fact, we'll never see an answer that attacks a premise directly (although it may shed more light on one), since both the premises and the answer choices (for a str/wkn) are taken as true. In that way, these are like Data Sufficiency. Statements 1 & 2 can't contradict each other, since they are both true! So why isn't A knocking out a premise? Because "some do" is never negated by "some don't." If I say "Some people won't rest until they get an 800, so I can create a service specifically for the most ambitious students," that underlying premise would not be negated by "Some people would be happy with 750, 700, or even 500." This doesn't make the previous statement any less true. Subbing "many" or "often" for "some" makes no difference either, since these are vague terms. Basically, the author is saying that there were a number of times when droughts lined up with collapses. This doesn't mean they always lined up, and the argument doesn't rely on that, so A doesn't really change the status of the argument in any way.

I hope that helps!

But option D says that it has maintained large stockpile of food, what if because of drought neighbouring states that do not maintain stockpiles of food attacks society that maintains food and water. This is basically strengthening the author claim.
Option B is attacking the premise on which claim is based. If it is unknown that agricultural output is reduced then how can author claim that lack of agricultural resource leads to internal and external stress

Posted from my mobile device

Ashu123321

First, an answer will never weaken a premise, so if it appears to do so, look again. In this case, the premise tells us that the cross-sections indicate drought, not drops in productivity. The author then combines this with info on civilizational collapse to build a hypothesis that drops in productivity occurred. They never claim to be able to infer this directly from the samples, so B has no effect.

As for D, we know nothing about whether one state ever attacked another to gain food and water, and we don’t need to know. The author is just claiming that drought might have left states without the resources needed to survive. If D is true, then maybe states *did* have the resources they needed, and so the hypothesis may be wrong. That’s all we need—a reason to question the connection between premise and conclusion.

Posted from my mobile device

Understanding the argument -
Scientist: Cross-sections of stalactites - calcite formations deposited on cave ceilings by seeping water - can reveal annual variations in rainfall in particular areas over hundreds and thousands of years. Opinion
We often found that when - according to these cross-sections - drought occurred in a particular area, it coincided with the collapse of an ancient society in that area.
- Fact. Conditional.
I hypothesize that drought reduced agricultural productivity in these areas, thereby leaving these societies without the resources needed to handle internal stresses and external threats. - Drought - reduced agricultural productivity - collapse (leaving these societies without the resources to handle internal stresses and external threats.)

This is not just X causing Y. This is X causing Z, which caused Y. We need to weaken the bridge or link, which is Z, leading to something else, say "A" caused Y.

Option Elimination -

A. Many droughts indicated in the cross-sections of stalactites do not correspond with the collapse of a society in that area. - This is ridiculous. "Many droughts indicated in the cross-sections of stalactites" as if "cross-sections of stalactites" is some hard disk or memory which, when opened (how?) showed that many (many can be at least 2) didn't correspond to collapse. Ok, let's assume that, yes, "cross-sections of stalactites" are a hard disk. Many can be at least 2, so two did not, but what about 98%? How about if 98% correlated? The conclusion is still valid. Distortion.

B. Information from the cross-sections of stalactites alone cannot reveal the level of agricultural output in an area at a particular time. - ok, so when we say it alone, didn't we already establish the connection by saying it's not alone? There are others as well. So it means it contributed along with others. Strengthen.

C. Most of the societies that collapsed during droughts did so when internal power struggles coincided with military raids from neighboring societies. - This is a big trap as it doesn't even talk about the bridge, which is agricultural productivity. It just states X, which is drought, and Y, which is collapse. Then, it shares another event happening simultaneously: internal power struggles coinciding with military raids from neighboring societies. Did it establish or break any connection? No. It just added some "B" events. It's a pseudo "A" or another cause: It just played with our rule book and considered it the alternate reason. Let me share one hypothetical situation to make it clear. Most of the societies that collapsed during droughts did so when Shakira danced. Did it establish that "Shakira's dance" caused the collapse, and it's an alternate reason? No, it just shared some random unrelated or related event and created a pseudo-alternate cause without touching, breaking, or making any causal connection with "Y." The Scope of our argument is to weaken: Drought - reduced agricultural productivity - collapse. Did it talk about the scope of the argument? No. Most societies that collapsed during droughts did so when X. Collapse and X are independent events without any link between them. Distortion.

D. Most of the societies that collapsed during droughts maintained large stockpiles of food and water at the time of their collapse. - It directly deals with the linkage and breaks the link. We don't know how long these stockpiles last, but will that matter here? We are just trying to break the linkage that "Drought - reduced agricultural productivity - collapse (leaving these societies without the resources to handle internal stresses and external threats.). The mere presence of the "large stockpiles" at the time of collapse casts doubt that "agricultural productivity" was the reason. Even if the stockpiles didn't last indefinitely, their presence suggests that the societies had enough resources to withstand temporary agricultural shortages caused by droughts, weakening the direct link between drought and collapse proposed by the scientist's hypothesis.

E. Information from stalactites also suggests that the collapse of some societies coincided with periods of abnormally high rainfall. - It may suggest 100 other things that we are not concerned about. And "some societies" can be at least 2. How about the remaining 98%? At best, it's out of scope.

Hi DmitryFarber MartyMurray KarishmaB egmat

I have few concerns with this question :

1. I first deliberately ignored hypothesis - 'Drought causes collapses' and assumed that author is just giving the hypothesis - 'How Drought can cause collapse ?', then I saw the 'support' could be the missing link between - Drought and limited resources available, and option D is weakening that support, Is my reasoning correct ?

2. I have understood how D could weaken the hypothesis - 'Drought causes collapses', but its not explicitly mentioned that Author's hypothesis is ' Drought causes collapses', though the tone of the hypothesis mentioned is going in that direction. Are we safe to apply extra brain to see what author intend to say once we get the gist that its 'correlation - causation arguement', asking because sometimes, we are instructed to stuck with the conclusion/hypothesis itself.

3. Its asking to weaken the 'support', so correlation is also a support for the above hypothesis ? right ?, if yes, then any alternate cause/ reverse causalty can also weaken the support apart from option D ?

Kindly can you help with the above points ?

Thanks !­

SnorLax_7

The author's conclusion is a bit more specific than "drought causes collapse." It's "when collapses occurred in these particular places, drought led to this specific problem (reduced productivity --> lack of resources) that led to collapse." So yes, the author believes that droughts led to the collapses, but we want to address the more specific point they are making. If you look at D, it doesn't do much to tell us whether droughts caused collapses. It just gives us information that makes this SPECIFIC mechanism of collapse (lack of resources) seem less likely. If there were plenty of resources, maybe the cause of collapse was something else, even if that something else was still the result of a drought.

I think that covers #1 and #2. (Let me know if it doesn't). As for #3, since we aren't just trying to prove that droughts caused collapses, additional information about the correlation between the two wouldn't do much. Strengthening a correlation is a helpful strengthen when the current data on correlation is weak or anecdotal (e.g. one city had a drought and collapsed), and *breaking* a correlation is a good weaken, but only if we are suggesting that the proposed cause is what *always* happens. (If we thought that all droughts always caused collapse, then a drought without a collapse would be a weaken, and if we thought that all collapses were caused by droughts, then a collapse without a drought would weaken.) In this case, we already have a strong correlation in the premises, and the author is only arguing that drought had this effect in certain cases, not that it's what ALWAYS happens, so there's nothing else we need on the correlation front. What we really want is information about causation. So yes, a different cause could provide a good weaken, but the answer would have to be very carefully written to show why some other cause looks any more likely than the one on offer.­

absolutely clear now, Thanks a lot DmitryFarber !

­

Cross-sections of stalactites can reveal annual variations in rainfall in particular areas over hundreds and thousands of years.

Premises:

We often found that when - according to these cross-sections - drought occurred in a particular area, it coincided with the collapse of an ancient society in that area.

Hypothesis:

Drought reduced agricultural productivity in these areas, thereby leaving these societies without the resources needed to handle internal stresses and external threats.


The argument says that droughts coincided with collapse of ancient societies. The hypothesis is that the drought reduced agricultural productivity thereby leaving no resources to handle threats and stresses. We need to weaken the hypothesis. We need to say that reduced agricultural productivity and lack of resources due to drought may not be the reason for fall of these societies.

A. Many droughts indicated in the cross-sections of stalactites do not correspond with the collapse of a society in that area.



The argument says that the link was found ‘often’, not always. So, this is irrelevant. 



B. Information from the cross-sections of stalactites alone cannot reveal the level of agricultural output in an area at a particular time.



Stalactites only tell us about drought, not about agricultural production. The argument doesn’t make any such claim.



C. Most of the societies that collapsed during droughts did so when internal power struggles coincided with military raids from neighboring societies.



The hypothesis says that the drought leaves the society vulnerable to internal stresses and external threats. The fact that both occurred together does not conflict with our hypothesis.  



D. Most of the societies that collapsed during droughts maintained large stockpiles of food and water at the time of their collapse.



This option tells us that the societies maintained their resources so drought would not have led to ‘no resources’. Hence, the reason for the fall of the society at that time must be something else. This weakens our hypothesis. Correct.



E. Information from stalactites also suggests that the collapse of some societies coincided with periods of abnormally high rainfall.

It is irrelevant to our argument. We are only interested in the drought - fall of societies link.

Answer (D)

Discussion on Weaken Questions: https://youtu.be/EhZ8FKkfy0k
 

Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.