Is this a flaw or a weaken question? How to identify this? Whats the main difference between the two ? and their approaches? How to use elimination to solve this? Please provide detailed explanation.

Also , the ans explanation for C says => The researchers assume that the low levels of calcium cause the polyps rather than the reverse: that the polyps somehow prevent the body from absorbing calcium. So if the causal relationship were reversed, eating calcium-rich foods would not have the desired effect.


Its clearly says that low calcium -> polyps .... How can we know that researchers assume. If we say that there is an assumption of causality and we are suspicious about causal relationship then how can there ever be causality

Researchers have noticed that people whose blood shows abnormally low levels of calcium usually have laryngeal polyps, which can permanently damage vocal cords and result in partial or even total loss of voice. In order to reduce the risk of polyps, the researchers recommend a diet high in calcium-rich foods such as dairy and green, leafy vegetables.

Which of the following, if true, most strongly suggests that following the researchers' recommendation would NOT be effective?

a)Dairy contains compounds that are difficult for many people to digest.

b)Laryngeal polyps sometimes disappear without treatment.

c)Laryngeal polyps cause a change in body chemistry that blocks the absorption of calcium.

d)Fresh vegetables are not always available in all seasons.

e)Low levels of calcium can sometimes be remedied with vitamin pills.

i am obv not an instructor so take it with a grain of salt but....

first, when you say "is this a flaw ..... question" do you mean find a flaw in reasoning type question? if so, this is not that type of question. in my exp. you will be asked to find a flaw in the reasoning. i wouldn't worry too much about trying to bucket questions like that because the strategy for either of these two types of questions is going to be relatively the same. we need to deconstruct the argument and weaken it. off the top of my head we can weaken the argument by doing the following:
- bring in outside information that invalidates/weakens the assumptions
- show that other factors attribute to the casual relationship. if the argument says that A causes B, it is saying that A is the sole cause of B. Showing that C also causes B weakens the argument and dillutes the significance of the casual relationship between A and B
- prove the opposite: B causes A
- prove that a causual relationship simply does not exist
- show that it exists by chance/on-off occurrence

i am obv missing some stuff and there there are a few more .....it can be broken down further by group/type of question. the point that i am trying to make is the following: i think you are better of focusing on identifying the conclusion, assumptions, premises and figuring out how to deconstruct the argument. if we understand these components of the argument and how they interact (what causes what), we can easily deconstruct the argument and either break it (weaken) or strengthen it.

i am not sure what you are saying here...
Its clearly says that low calcium -> polyps .... How can we know that researchers assume. If we say that there is an assumption of causality and we are suspicious about causal relationship then how can there ever be causality

anyhow ill try to break this argument down below:

premise 1: there is a positive corr between low level of calc and lage polyps
conclusion: diet high in calcium will reduce the risk of polyps
ass
underlying assumption: high calcium intake will reduce the risk of polyps

this argument is crappy because it is essentially creating a casual relationship from a casual relationship. just because A and B move in the same direction does not mean that A causes B or visa versa. thats actually somewhat irrelevant given the answer choices:

we have to choose a statement that will WEAKEN the conclusion and make the argument ineffective.

a) nobody cares. not related to conclusion. so what if they are difficult to digest. nobody said it would be easy. irrelevant

b) nobody cares. not related to conclusion.
again great news but irrelevant. this does not really alleviate the problem and has nothing to do with calcium.

c) okay these polyps block absorption of calcium. go back to the conclusion. we established that the conclusion of the argument is "diet high in calcium will reduce the risk of polyps
ass". if polyps block absorption of calcium this whole plan is going down the drain. they can literary OD on calcium and it will do nothing to polyps.

d) not related to conclusion. has nothing to do with calcium.

e) not related to conclusion. we are trying to reduce the risk of polyps, NOT, increase our levels of calcium + vitamin pills have nothing to do with calcium/milk

The answer explanation says that researchers believe this => i am not sure what you are saying here...
low calcium -> polyps ....but according to me this is no assumption ...There is clear indication of this causal relationship in the stimulus but the explanation doubts that this can be true...So my question is if we keep doubting all causal relationships then how can we know when to assume causal relationship exists and when it doesnt....I am confused about that...It says we need proof that causal relationship exists..my question is what do you mean by proof ??? Doesnt clear statement mean that it is a proof???

is the answer C?
all other answer choices seems like out of scope.

anjana - yeah its C

sidd - i think you may be overthinking this or i am missing your point. what do you mean we keep doubting all causal relationships? the answer choices and the stimulus do not necessarily have to agree. for some answer, it is okay to bring in outside information to strengthen or weaken the argument.

we were given a premise and a conclusion. as you said, they were both clearly explained in the argument. the argument depends on high intake of calcium. we were asked to weaken the argument. answer choice C weakens the argument by stating that polyps block calcium. that completely invalidates the conclusion stated in the argument. that's it.

You may find this link helpful as it deals with this specific problem:
http://www.manhattangmat.com/articles/causation-CR.cfm

George has made some good points. The argument's premise is that low calcium levels and polyps are found together. The conclusion is that the low calcium levels CAUSED the polyps. To conclude this, we have to assume that it is not in fact the polyps causing the low calcium levels. Answer choice C destroys this assumption and is thus the best choice to weaken the conclusion.

_________________
Jamie Nelson
ManhattanGMAT Instructor