Critical Reasoning

katrizenis wrote:124. It is widely assumed that people need to engage in intellectual activities such as solving crossword puzzles or mathematics problems in order to maintain mental sharpness as they age. In fact, however, simply talking to other people-that is, participating in social interaction, which engages many mental and perceptual skills-suffices
. Evidence to this effect comes from a study showing that the more social contact people report, the better their mental skills.

Which of the following, if true, most seriously weakens the force of the evidence cited?

(A) As people grow older, they are often advised to keep exercising their physical and mental capacities in order to maintain or improve them.
(B) Many medical conditions and treatments that adversely affect a person's mental sharpness also tend to increase that person's social isolation.
(C) Many people are proficient both in social interactions and in solving mathematical problems.
(D) The study did not itself collect data but analyzed data bearing on the issue from prior studies.
(E) The tasks evaluating mental sharpness for which data were compiled by the study were more akin to mathematics problems than to conversation.

src_saurav wrote:Mitch, i tried to reject the study here. I chose D as it says that study is based on past collected data.

Please explain.

src_saurav wrote:Hi Mitch,

Please explain when we can prove a study sample to be inconclusive.

GMATGuruNY wrote:

katrizenis wrote:124. It is widely assumed that people need to engage in intellectual activities such as solving crossword puzzles or mathematics problems in order to maintain mental sharpness as they age. In fact, however, simply talking to other people-that is, participating in social interaction, which engages many mental and perceptual skills-suffices
. Evidence to this effect comes from a study showing that the more social contact people report, the better their mental skills.

Which of the following, if true, most seriously weakens the force of the evidence cited?

(A) As people grow older, they are often advised to keep exercising their physical and mental capacities in order to maintain or improve them.
(B) Many medical conditions and treatments that adversely affect a person's mental sharpness also tend to increase that person's social isolation.
(C) Many people are proficient both in social interactions and in solving mathematical problems.
(D) The study did not itself collect data but analyzed data bearing on the issue from prior studies.
(E) The tasks evaluating mental sharpness for which data were compiled by the study were more akin to mathematics problems than to conversation.

Premise: The more social contact people report, the better their mental skills.
Conclusion: To maintain mental sharpness...social interaction suffices.

This is a CAUSAL ARGUMENT.
In a causal argument, events A and B are observed together, and the argument concludes that A causes B.
Here, social interaction and mental sharpness are observed together, and the argument concludes that social interaction CAUSES mental sharpness.
Put another way, the argument concludes that a LACK of social interaction causes a LACK of mental sharpness.

One way to weaken a causal relationship is to introduce an ALTERNATE CAUSE.
Answer choice B:
Many medical conditions and treatments that adversely affect a person's mental sharpness also tend to increase that person's social isolation.
Here, a lack of mental sharpness and a lack of social interaction are both caused by MEDICAL CONDITIONS AND TREATMENTS, weakening the conclusion that a lack of social interaction causes a lack of mental sharpness.

The correct answer is B.

Mo2men wrote:Hi Mitch,
Although I agree that B is the correct answer, I think it is not an alternate cause. I believe it is introducing a 3rd factor that muddle the relationship between social interaction and mental skills. Answer B is not on the ordinary form of giving direct alternate cause. For example, it does say that spending time with parents affect the mental skills.

What do you think??

gmat_for_life wrote:My question is that if A causes B, then can we directly negate both sides as in NOT A-> NOT B or should it be NOT B-> NOT A? Which correlation out of the two is being applied in this case?

Regards,
Amit

GMATGuruNY wrote: EVIDENCE...comes from A STUDY showing that the more social contact people report, the better their mental skills.
Since the study provides EVIDENCE, the study serves as a PREMISE.
A premise is a FACT; it cannot be weakened.
Eliminate any answer choice that attempts to weaken a premise.
D: The study did not itself collect data but analyzed data bearing on the issue from prior studies.
Since D attempts to weaken the premise offered by the study, eliminate D.

GMATGuruNY wrote: A -> B does not imply that Not A -> Not B.

GMATGuruNY wrote:

katrizenis wrote:124. It is widely assumed that people need to engage in intellectual activities such as solving crossword puzzles or mathematics problems in order to maintain mental sharpness as they age. In fact, however, simply talking to other people-that is, participating in social interaction, which engages many mental and perceptual skills-suffices
. Evidence to this effect comes from a study showing that the more social contact people report, the better their mental skills.

Which of the following, if true, most seriously weakens the force of the evidence cited?

(A) As people grow older, they are often advised to keep exercising their physical and mental capacities in order to maintain or improve them.
(B) Many medical conditions and treatments that adversely affect a person's mental sharpness also tend to increase that person's social isolation.
(C) Many people are proficient both in social interactions and in solving mathematical problems.
(D) The study did not itself collect data but analyzed data bearing on the issue from prior studies.
(E) The tasks evaluating mental sharpness for which data were compiled by the study were more akin to mathematics problems than to conversation.

Premise: The more social contact people report, the better their mental skills.
Conclusion: To maintain mental sharpness...social interaction suffices.

This is a CAUSAL ARGUMENT.
In a causal argument, events A and B are observed together, and the argument concludes that A causes B.
Here, social interaction and mental sharpness are observed together, and the argument concludes that social interaction CAUSES mental sharpness.
Put another way, the argument concludes that a LACK of social interaction causes a LACK of mental sharpness.

One way to weaken a causal relationship is to introduce an ALTERNATE CAUSE.
Answer choice B:
Many medical conditions and treatments that adversely affect a person's mental sharpness also tend to increase that person's social isolation.
Here, a lack of mental sharpness and a lack of social interaction are both caused by MEDICAL CONDITIONS AND TREATMENTS, weakening the conclusion that a lack of social interaction causes a lack of mental sharpness.

The correct answer is B.

RBBmba@2014 wrote:

GMATGuruNY wrote: EVIDENCE...comes from A STUDY showing that the more social contact people report, the better their mental skills.
Since the study provides EVIDENCE, the study serves as a PREMISE.
A premise is a FACT; it cannot be weakened.
Eliminate any answer choice that attempts to weaken a premise.
D: The study did not itself collect data but analyzed data bearing on the issue from prior studies.
Since D attempts to weaken the premise offered by the study, eliminate D.

Even if D is true, I think, it doesn't affect the CONCLUSION that the more social contact people report, the better their mental skills.
Isn't it ?

RBBmba@2014 wrote:

GMATGuruNY wrote: A -> B does not imply that Not A -> Not B.

NOT able to understand this!

GENERALLY, in a GMAT STRENGTHEN CR, if we've A caused B or A has led to B or If A then B, then any answer choice that indicates If NOT A then NOT B,should be a potential STRENGTHENER, I guess. (because MUST BE TRUE aspect doesn't hold true in a STRENGTHEN CR)

Am I correct ?

Marty Murray wrote:Mitch's point is simply that A -> B does not IMPLY Not A -> Not B.

In other words, the fact that A causes B cannot be used to conclude that if A is not the case then B is not the case.

B could be caused by things other than A.

If you drink too much you will get sick does not imply that if you do not drink too much you will never get sick.