Critical Reasoning

In an attempt to explain the cause of malaria, a deadly infectious disease common in tropical areas, early european settlers in Hong Kong attributed the malady to poisonous gases supposedly emanating from low-lying swampland. Malaria, in fact, translates from the Italian as "bad air." In the 1880s, however, doctors determined that Anopheles mosquitoes were responsible for transmitting the disease to humans after observing that the female of the species can carry a parasitic protozoan that is passed on to unsuspecting humans when a mosquito feasts on a person's blood.

Which function does the statement in boldface fulfill with respect to the argument presented above?

(A) It provides support for the explanation of a particular phenomenon.
(B) It presents evidence which contradicts an established fact.
(C) It offers confirmation of a contested assumption.
(D) It identifies the cause of an erroneous conclusion.
(E) It proposes a new conclusion in place of an earlier conjecture.

Spoiler:

[spoiler]The correct answer is A. I understand why A is the best choice, but I am still trying to figure out the explanation. The boldface represents a premise for, which is used to support the conclusion "doctors determined that Anopheles mosquitoes were responsible for transmitting the disease to humans." However, isn't this statement actually a fact? The author is not pushing for a conclusion in the last sentence, but rather stating a fact that in 1880s that scientists observed a female mosquito carrying a parasitic protozoan.

In addition, compare this to an example of a fact earlier in the chapter:

"Certain genetic diseases are more prevalent among certain ethnic populations. For example, Tay Sachs disease, a usually fatal genetic condition caused by the build-up of the gangliosides in nerve cells, occurs more frequently among Ashkenazi Jews than among the the general population." (p. 16 MGMAT Book 6)
So, my question is, what is the difference between these two?[/spoiler]

I am too confused with A and B.

A is right saying that this supports the explanation by doctors after 1880.

However, B is also right since the bold statement is an evidence contradicting the previous established fact that malaria was caused due to poisonous gases.

Could someone please help ?

OneTwoThreeFour wrote:In an attempt to explain the cause of malaria, a deadly infectious disease common in tropical areas, early european settlers in Hong Kong attributed the malady to poisonous gases supposedly emanating from low-lying swampland. Malaria, in fact, translates from the Italian as "bad air." In the 1880s, however, doctors determined that Anopheles mosquitoes were responsible for transmitting the disease to humans after observing that the female of the species can carry a parasitic protozoan that is passed on to unsuspecting humans when a mosquito feasts on a person's blood.

Which function does the statement in boldface fulfill with respect to the argument presented above?

(A) It provides support for the explanation of a particular phenomenon.
(B) It presents evidence which contradicts an established fact.
(C) It offers confirmation of a contested assumption.
(D) It identifies the cause of an erroneous conclusion.
(E) It proposes a new conclusion in place of an earlier conjecture.

Spoiler:

[spoiler]The correct answer is A. I understand why A is the best choice, but I am still trying to figure out the explanation. The boldface represents a premise for, which is used to support the conclusion "doctors determined that Anopheles mosquitoes were responsible for transmitting the disease to humans." However, isn't this statement actually a fact? The author is not pushing for a conclusion in the last sentence, but rather stating a fact that in 1880s that scientists observed a female mosquito carrying a parasitic protozoan.

In addition, compare this to an example of a fact earlier in the chapter:

"Certain genetic diseases are more prevalent among certain ethnic populations. For example, Tay Sachs disease, a usually fatal genetic condition caused by the build-up of the gangliosides in nerve cells, occurs more frequently among Ashkenazi Jews than among the the general population." (p. 16 MGMAT Book 6)
So, my question is, what is the difference between these two?[/spoiler]

pesfunk wrote:I am too confused with A and B.

A is right saying that this supports the explanation by doctors after 1880.

However, B is also right since the bold statement is an evidence contradicting the previous established fact that malaria was caused due to poisonous gases.

Could someone please help ?

[

Even I chose B when I read the problem for the first time

The problem with B is that it says that the bold faced portion contradicts the ESTABLISHED FACT.
According to MGMAT ,the original belief cannot be labeled as fact.It was a MISTAKEN BELIEF.
& if we assume that the established fact is the later conclusion by the doctors,then the statement doest not contradict the established fact.Rather it supports the conclusion.

I am not really convinced with A
But it is better than B

I was actually struggling between A and C.
B is incorrect because the idea that bad air causes malaria is NOT A FACT (it was never proved, but it was just believed to be true), it is a B-world

But what is the difference between A and C when?

Infact if i had to chose i wud too chose B coz it directly says about the evidence planted which supports a conclusion that contradicts the earlier fact !

May be RON can pitch in to make it clear. A would have been my second choice but not the first !

Guys who selected B: the belief that malaria is caused by the bad air is not A FACT, it is belief (or superstition or theory - whatever but not the fact).

Consider: before Copernicus people believed the sun rotates around the earth, while in reality that is not true. so believe of the people is whatever but not the fact.

I know the first part of the argument is not a fact, but rather a belief. However my question is for the second part:

In the 1880s, however, doctors determined that Anopheles mosquitoes were responsible for transmitting the disease to humans after observing that the female of the species can carry a parasitic protozoan that is passed on to unsuspecting humans when a mosquito feasts on a person's blood.

Why isn't this a fact? (The answer states that this statement represents a conclusion and a premise for.) This clearly isn't a belief because the doctors were able to observe female mosquitos can carry a parasitic protozoan. Plus, nowhere in the argument does it contends further scientific findings disproved this notion. So we as the reader are accepting that to this day, female mosquitos do carry parasitic protozoan and the protozoan is the cause of transmitting disease.

By the way, C is wrong because the argument does not present any contested arguments on the source of malaria. It is simply stating a brief history on the origins of the beliefs in malaria, ending with actual findings in 1880s.

This is an interesting question and conversation, so I thought I'd weigh in.

Instead of trying to somehow logically prove the distinction between "fact" and "argument," I want to stress the way the GMAT thinks about Arguments. Some of you may have studied LSAT questions, which are far more grounded in formal logic. On the GMAT, an Argument is composed (I'm sure you've all heard this before but I want us to think about it again) of two pieces: Evidence and Conclusion. This means what we should be looking for is someone (the author, usually) who is making a point, and then a "why" for their point.

Those of you who have pointed out that the "doctors determined..." sentence is a fact are correct in that it's given, as a fact, that doctors in fact made this determination. However, the doctors themselves are making a classic GMAT argument, and the only argument-style sentence in the entire stimulus. The doctors claim one thing because of some piece of evidence -- the bolded statement is this Evidence. Furthermore, it is absolutely right to label the doctors' determination as an "explanation" of malaria; this should lead us directly to (A).

For (B), first of all, as many of you have pointed out, the idea that malaria was "bad air" is never clarified as an "established fact"; second of all, the bolded statement does not actually contradict this fact, but instead provide support for a conclusion (the mosquito conclusion) which itself contradicts the original supposition. For (C), again, the evidence itself only confirms the doctors' conclusion, which is never said to be contested.

I think some of you have read the argument as it if went like this: "Here's one opinion, and now here's another opinion." Instead, the argument is meant to have the following structure: "Here's a problem (the clearly wrong/bad explanation of malaria, and here's the solution (the correct explanation), and here's the evidence for the correct explanation." It really helps to identify when the GMAT is giving you an Argument: A theory, and a "why" for that theory. We get this in the final sentence, we see the doctors' argument as a Conclusion/Evidence pair, and we can answer the question.

The more we can anticipate what the GMAT will give us and recognize when they're falling into their classic patterns, and the less we have to reason from scratch on each question, the better we'll do on CR.

Thanks Adam! That was very insightful.

Thanks Ron.