Critical Reasoning

Neuroscientists are making progress in discovering more about the cause of Alzheimer’s disease. Alzheimer’s disease patients suffer from dementia and sever memory loss. Autopsies performed on such patients have revealed the presence of brain lesions caused by abnormal protein deposits. Similar deposits are also found in the brains of elderly patients who do not suffer from Alzheimer’s disease. It follows that everyone who lives long enough will eventually develop Alzheimer’s disease.

Which one of the following statements, if true, most seriously undermines the conclusion that everyone who lives long enough will eventually develop Alzheimer’s disease?

(A) The lesions found in the brains of non-Alzheimer’s disease patients are far less extensive than those found in the brains of Alzheimer’s disease patients.

(B) The developing brain produces a greater number of cells than it will ever use. The extra cells are later destroyed by what biologists call “programmed cell death.”

(C) The procedure that allows scientists to discover the presence of protein deposits during an autopsy is not yet refined enough to ensure detection of the lesions in all patients.

(D) Autopsies have shown that some people lack the chemical necessary for protein deposits to cause brain lesions.

(E) Though most Alzheimer’s disease patients develop the disease when they are in their late fifties to early seventies, the frequency of patients who develop the disease in their forties is on the rise.

OA after discussion

I would go with D

(A) The lesions found in the brains of non-Alzheimer’s disease patients are far less extensive than those found in the brains of Alzheimer’s disease patients. – the lesions found in the brains of non-Alzheimer’s disease and Alzheimer’s disease patients are not compared in the argument

(B) The developing brain produces a greater number of cells than it will ever use. The extra cells are later destroyed by what biologists call “programmed cell death.” – a greater number of cells produced is not connected with brain lesion caused by ubnormal protein deposits, so it is out of scope in the argument

(C) The procedure that allows scientists to discover the presence of protein deposits during an autopsy is not yet refined enough to ensure detection of the lesions in all patients. – is wrong as if the autopsies is not perfect and there can be some mistakes, there is no guarantee that brain lesions of some patients were correctly detected and so it is possible that elderly patients don’t have such lesions.

(D) Autopsies have shown that some people lack the chemical necessary for protein deposits to cause brain lesions. – is CORRECT as if people lack the chemical necessary for protein deposits to develop brain lesions, such people will not suffer Alzheimer’s disease even if they live long. This weakens the conclusion

(E) Though most Alzheimer’s disease patients develop the disease when they are in their late fifties to early seventies, the frequency of patients who develop the disease in their forties is on the rise. – the frequency of patients is out of scope in the argument

IMO D..Please post OA

would go for C

to weaken conclusion: everyone who lives long enough develops Alzheimers

A. out of scope

B. cell death is out of scope

C. says the autopsy procedures are not refined enough to ensure proper detection in all patients=> tests are not reliable/foolproof to make the given conclusion. weakens the conclusion

D. if some people lack chemicals that cause lesions, those people do not have Alzheimers. but we do not know if those people are not in their old age. does not weaken IMO

E. we do not know if 40s is long enough.

It has to be D

(C) The procedure that allows scientists to discover the presence of protein deposits during an autopsy is not yet refined enough to ensure detection of the lesions in all patients.

It is true that we can bring outside information in weaken Q's but here is a point to note :

Whenever,we have two options, example in this case :

C => brings outside info
D => Gives an alternate Explanation

chose D(You may consider these questions to be Resolve the paradox Q's)

Hope this helps

D for me too

Conclusion says everyone will develop the disease

D) says some people will not develop the disease..

So D weakens the argument...

IMO - E

I eliminated C because if medical procedures can easily detect the presence of lesions then more number of patients can be easily detected with the symptoms. Hence this might strengthen the argument.

E says that even younger people are begining to be detected with this disease. So it is not about living long enough to suffer from this disease. There can be some other reason for this disease because of which young people are falling prey to the disease.

No need to live long enough. people in 40s are getting it.

(e)

<double post>

<double_post>

C - Everyone who live long develop A

Causation is assumed here. Everyone living long --> Develop A

To weaken break the causal relationship.

A) The lesions found in the brains of non-Alzheimer’s disease patients are far less extensive than those found in the brains of Alzheimer’s disease patients.

Extensiveness of lesions - Out of Scope OOS

(B) The developing brain produces a greater number of cells than it will ever use. The extra cells are later destroyed by what biologists call “programmed cell D€@th.”

“programmed cell D€@th.” - OOS

(C) The procedure that allows scientists to discover the presence of protein deposits during an autopsy is not yet refined enough to ensure detection of the lesions in all patients.

Breaks the causal relationship by stating that the method to conclude the causal relationship is not foolproof -- Choose C

(D) Autopsies have shown that some people lack the chemical necessary for protein deposits to cause brain lesions.

Argument is about everyone WHO livelong. Would have been correct if it says that 'some people who livelong' coz conclusion was about EVERYONE

(E) Though most Alzheimer’s disease patients develop the disease when they are in their late fifties to early seventies, the frequency of patients who develop the disease in their forties is on the rise.

Fifties, forties. We cannot determine whether forties is long enough

IMO E

OA plzz..

(D) is OA

In my opinion D is the most logical one