Critical Reasoning

Although exposure to asbestos is the primary cause of mesothelioma, a slow-developing cancer, researchers believe that infection by the SV40 virus is a contributing cause, since in the United States 60 percent of tissue samples from mesotheliomas, but none from healthy tissue, contain SV40. SV40 is a monkey virus; however, in 1960 some polio vaccine was contaminated with the virus. Researchers hypothesize that this vaccine was thesource of the virus found in mesotheliomas decades later. Which of the following, if true, most strongly supports the researchers' hypothesis?

A. SV40 is widely used as a research tool in cancer laboratories.
B. Changes in the technique of manufacturing the vaccine now prevent contamination with SV40.
C. Recently discovered samples of the vaccine dating from 1960 still show traces of the virus.
D. In a small percentage of cases of mesothelioma, there is no history of exposure to asbestos.
E. In Finland, where the polio vaccine was never contaminated, samples from mesotheliomas do not contain SV40.



I know the answer is E, but what is the take-way???

Hii tracyyahoo,

I cannot understand what you mean by "take-away".

here you are asked to support the researchers' hypothesis,

The hypothesis is : in 1960 some polio vaccine was contaminated with the SV40 virus, and today this vaccines are the source of the virus in the human tissue. This could be strengthen by showing that if it were not contaminated, then today there are no other source by which the virus could come - We are showing that the only source of SV40 virus in human tissue is the contamination of the polio vaccines in the past, and there are no other source for this - this is one way to support the hypothesis.

So I hope you got why E is correct.

You can also consider cause and effect here:

cause ( contamination in the past ) ------------> (the source of virus in human tissue atpresent), effect.

So how can a causality can be strengthened :
1. no other cause is resonsible for the stated effect.
2. if the cause is not there then the effect is also not there.
3. the reversal of the cause and effect is not possible.

E fits the no.2 templates.

Hope this helps !!

avik.ch wrote:Hii tracyyahoo,

I cannot understand what you mean by "take-away".

here you are asked to support the researchers' hypothesis,

The hypothesis is : in 1960 some polio vaccine was contaminated with the SV40 virus, and today this vaccines are the source of the virus in the human tissue. This could be strengthen by showing that if it were not contaminated, then today there are no other source by which the virus could come - We are showing that the only source of SV40 virus in human tissue is the contamination of the polio vaccines in the past, and there are no other source for this - this is one way to support the hypothesis.

So I hope you got why E is correct.

You can also consider cause and effect here:

cause ( contamination in the past ) ------------> (the source of virus in human tissue atpresent), effect.

So how can a causality can be strengthened :
1. no other cause is resonsible for the stated effect.
2. if the cause is not there then the effect is also not there.
3. the reversal of the cause and effect is not possible.

E fits the no.2 templates.

Hope this helps !!

Hi Avik

I think you thought of saying the reverse. if effect is not there, then cause is not there.

Thanks
user123321

hii user123321,


I would say both are correct - its the way you look at this:

no cause ---------> no effect :

smoking ( cause) ---> kills ( effect)

If you stop smoking then you will not die.

The only thing you have to prove is that "kills" cannot happen without the prior action of "smoking".

From this, the weakening of the causality is by showing that these two are independent events --

1. no cause : effect is there
2. cause is there : effect is not there

I mean take way....

When I read the passage I can immediately go to E... Beucase when I do this question I immediately eliminate E...

Or I think this question is stupid because it just supports the question reversely, it doesn't have any meaning here or something for the test taker to think about or to learn from the exam..

it's like you mother is pig... then the correct answer to support it is like not pig is not your mother...

is that what you

I am not an expert to question the validity of this question. For me, it was a good question.

tracyyahoo wrote: it's like you mother is pig... then the correct answer to support it is like not pig is not your mother...

This analogy provided by you is not a causality. This question is talking about a causality.

The rule you are stating here is a conditional reasoning .

A implies B --- > if i will study, i will pass the exam.
Not A implies Not B ---> if I dont study, i will not pass the exam.

tracyyahoo wrote: is that what you

what is this !! you want to mean that my mother is a pig...? no she is not...

Why you want to use such a language ? and what made you do so ? its bad !!

Thanks !!

I mean take way....

I assume its take - away. Avik here has provided a great explanation above.

You can also consider cause and effect here:

cause ( contamination in the past ) ------------> (the source of virus in human tissue atpresent), effect.

So how can a causality can be strengthened :
1. no other cause is resonsible for the stated effect.
2. if the cause is not there then the effect is also not there.
3. the reversal of the cause and effect is not possible.

E fits the no.2 templates.

So for a weaken question with causality, you can use the above techniques to find the right answer and that is the take away.

When I read the passage I can immediately go to E...

Why did you go specifically to option E ? Did you find what's wrong with others ?

Beucase when I do this question I immediately eliminate E...

On what basis did you eliminate this answer choice ?

Or I think this question is stupid because it just supports the question reversely, it doesn't have any meaning here or something for the test taker to think about or to learn from the exam..

This is a good question by the way. CR questions are unique in their own ways. There are no patterns/take aways for each question which you can apply on other questions. All you can learn is the above general techniques such as Causality for strengthen weaken scenarios, negation techniques for assumption, etc., which you can apply on other questions. Once you get some idea for all the types, you can let your thinking do the rest.

it's like you mother is pig... then the correct answer to support it is like not pig is not your mother...

is that what you

I don't get what you meant by this. But its quite offensive and refrain using such words in a forum

I doesn't mean that your mother is pig or not pig not your mother, such like of logic in here...

I mean, when I see this question, the first impression is eliminating E here... I want take-away of this type of question.... or similar questions....

this is not very good question, I think it is lame

What do you mean by take-away ? If you could explain us more elaborately on what your doubt is regarding this question, then everybody is here to help you out.

tracyyahoo wrote:I doesn't mean that your mother is pig or not pig not your mother, such like of logic in here...

First of all , what I can infer from your post - is that you wanna mean different thing. Anyway, the analogy you are using here is called conditional reasoning and not causality. Refer my above post on this.

tracyyahoo wrote: I mean, when I see this question, the first impression is eliminating E here... I want take-away of this type of question.... or similar questions....

Why ? for a strengthening question, you have to bring something from outside to strengthen something. You have to.

tracyyahoo wrote: this is not very good question, I think it is lame

again, i would like to repeat that : the validity of a question is not in the scope of the test taker - neither we have to spend time on this.

What is the source of this question ? if it is GMAT prep ( I haven't seen this question in OG), I would say, its the best - if not I can accept your point of view. I generally don't like spending and discussing the level and validity of any question, unless there is any major flaw in it.

The take away from this one is only causality. The best way to to understand the takeaway is to understand the stimulus and make a parallel stimulus out of it. There cannot be any better take away other than this.

Hope this helps !!

The source of this question is from GWD, it is very very stupid none GMAT test questions paper...

what is GWD ? Never heard of it.

I also went with E but I don't see any reason why C can be eliminated. What are your guys' thoughts?

sk8legend408 wrote:I also went with E but I don't see any reason why C can be eliminated. What are your guys' thoughts?

The researcher's hypothesis is that the contaminated virus is the source of the cancer.

C. Recently discovered samples of the vaccine dating from 1960 still show traces of the virus. - is wrong as it doesn't strengthen the hypothesis, it sort of re states whatever is already available in the stimulus researchers believe that infection by the SV40 virus is a contributing cause, since in the United States 60 percent of tissue samples from mesotheliomas, but none from healthy tissue, contain SV40

C may strengthen the researcher's belief above but not the hypothesis. Hope this helps

(E)