Critical Reasoning

Although exposure to asbestos is the primary cause for mesothelioma, a slow-developing cancer, researchers believe that infection by the SV40 virus is a contributing case, since in the US 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 the source 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 toll 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
[spoiler]
OA : E
Do you agree with OA? How did you you choose between C and E?
How did you eliminate C?
[/spoiler]

I eliminated "C" because we already knew that the vaccine was contaminated. This answer choice does not give us any new information.

sakali wrote:I eliminated "C" because we already knew that the vaccine was contaminated. This answer choice does not give us any new information.

Yes, we know vaccine was contaminated. But whether it could have an effect 40-50 years down the line is not known. So, knowing that those vaccine still have traces of SV40 gives a subtle new information that the virus can actually survive 40-50 years. So, it strengthens the hypotheses.

Vaccine contaminated in 1960---> (vaccine can survive 40-50 years) ---> vaccine is the the cause of cancer found today.

iamseer wrote: (vaccine can survive 40-50 years)

This is an assumption/outside information that is being brought into the argument. I would typically avoid this.

HTH.

maxpain wrote: This is an assumption/outside information that is being brought into the argument. I would typically avoid this.

oops!! my bad...
what I meant to type is:

Vaccine contaminated in 1960---> (Virus can survive 40-50 years) ---> vaccine is the the cause of cancer found today

yet more detailed:
vaccine was contaminated with virus SV40 in 1960 ---> (Virus is still present in those vaccine samples of 1960 i.e. virus can survive 40-50 years) ---> vaccine is the source of virus found in cancer tissue.

Ok here's an analogy to make things simpler...hopefully!!

David answers a question today. 50 years ago, David read a book that had the answer. The quiz master hypothesizes that reading that book helped David answer the question today.

Now, if we have to strengthen this hypothesis and 2 options are:

1. In a recent interview David mentioned that he remembers what he had read in that book.
2. Tom who never read the book, could not answer the question.

which one of the option would one choose?

Analogy:
David - Polio vaccine of US
Tom - Polio vaccine of Finland
Reading the book - contamination by virus
answering the question in quiz - virus in mesotheliomas
mentioned that he remembers - still show traces

iamseer wrote: Yes, we know vaccine was contaminated. But whether it could have an effect 40-50 years down the line is not known. So, knowing that those vaccine still have traces of SV40 gives a subtle new information that the virus can actually survive 40-50 years. So, it strengthens the hypotheses.

Vaccine contaminated in 1960---> (vaccine can survive 40-50 years) ---> vaccine is the the cause of cancer found today.

Vaccine in a bottle for 50 years ≠ Vaccine applied to someone 50 years ago

Know what I mean?

This just tells us that the vaccine is still contaminated. It does not say anything about the effects of the vaccine had it been applied to someone 50 years ago.

Can anyone explain why D is not a viable option?? I am sure I am missing something!!! Thanks in advance..

MRehman wrote:Can anyone explain why D is not a viable option?? I am sure I am missing something!!! Thanks in advance..

b'cos it is not relevant. It has nothing to do with author's hypotheses that the vaccine was the source.

HTH!!

Do you agree with OA? How did you you choose between C and E?
How did you eliminate C?

Hi,

Between C & E

Stimulus states-
'in 1960 some polio vaccine was contaminated with the virus. Researchers hypothesize that this vaccine was the source of the virus found in mesotheliomas decades later'

C States 'Recently discovered samples of the vaccine dating from 1960 still show traces of the virus' but this does not mean that the vaccine was contaminated in 1960. In other words the contamination could have taken place much before 1960.


E-
This is a simple Cause & Effect case. E merely shows that when the Cause (contamination of the polio vaccine) did not occur the Effect (finding of SV40 in samples from mesotheliomas) does not occur.
( Dont let the In Finland, beginning throw you off)

So E it is.

Hope I was able to help.

iamseer wrote:Although exposure to asbestos is the primary cause for mesothelioma, a slow-developing cancer, researchers believe that infection by the SV40 virus is a contributing case, since in the US 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 the source 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 toll 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
[spoiler]
OA : E
Do you agree with OA? How did you you choose between C and E?
How did you eliminate C?
[/spoiler]

my take :

Researchers believe : that (the virus is a contributing case) and that (presence of virus together with cancer in US is due to the contamination of polio vaccine in 1960).


In logic notation :

In US,

P -> Q

P = cancer together with virus
Q= contamination of virus


So, any option that adds a piece of info about either of these two beliefs would strengthen the argument.

Option C:

it just re-states that the vaccine was contaminated in 1960. Yes. the researchers already know that and it is a fact. This option adds nothing new to the argument.


Option E

it says that : no contamination - > no virus with cancer.

in logic terms

~Q -> ~P

where there was no contamination, there was no simultaneous occurrence of cancer and virus.

Makes us to think that, yes, contamination in 1960 might be a reason for this simultaneous occurrence.

In the end, if you observe, the first belief is not a hypothesis to be considered in this argument. It's like a trap.

HTH

Yes I agree that the answer is E - we are trying to support that the vaccine was the cause of the SV40 - you support a causal argument by eliminating another possible cause or showing that the effect did not happen if the cause was not there. That is what E does it says that when there was no contamination, there was no SV40 which supports that the vaccine was the source of the SV40. C doesn't really support at all - all it says is that the vaccine was contaminated, which we were already told as a fact in the argument so it doesn't help.

iamseer wrote:Although exposure to asbestos is the primary cause for mesothelioma, a slow-developing cancer, researchers believe that infection by the SV40 virus is a contributing case, since in the US 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 the source 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 toll 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
[spoiler]
OA : E
Do you agree with OA? How did you you choose between C and E?
How did you eliminate C?
[/spoiler]

cause and effect type of argument when asks about strengthening the argument then an answer , which does any of the following things can be a correct answer
1) shows that the cause is the only cause , that is there is no other cause for the stated effect
2) shows that whenver the effect occurs the cause occurs
3) whenever cause does not occur effect doesn't occurs
4) the stated effect is not reversible........memorize this one because in strenghtening CR this type of answers can be misunderstood as irrelevent
5)if the argument contains any survey or data then any aswer , which shows the validity of survey or accuracy of data is a correct ans
6) if the argument contains any survey or data then any aswer , which eliminates the doubt on data and survey is a correct ans.......(again In St CR , these answers are easy to miss)
coming th this particular CR
here Researchers hypothesize that this vaccine was the source (cause)of the virus (presence of virus is the effect)found in mesotheliomas decades later.

any of the above mentioned 6 types can be a correct ans
if u are aware of the pattern u will straight away select E ,which is playing the same role as mentioned in the 3rd point above(whenever cause does not occur effect doesn't occur)

C only tellls us that vaccine was contaminated with virus, but does not prove that vaccine was the source of the virus found in mesotheliomas decades later.

HTH

Thanks for your input tpr-becky, harshavardhanc, and thephoenix. Appreciate the quick response.

Thank you sakali, maxpain, MRehman, T11 for your contribution too.