Critical Reasoning

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 ?

GMATGuruNY wrote:A --> B does not imply that Not A --> Not B.
If we are told that daily news-watching causes depression, we cannot conclude that people who avoid the daily news are happy.
However, if an argument concludes that A --> B, this conclusion can be strengthened by showing that Not A --> Not B.
If an argument concludes that daily news-watching causes depression, this conclusion can be strengthened by showing that avoiding the daily news causes the depression to disappear.

RBBmba@2014 wrote:

GMATGuruNY wrote:A --> B does not imply that Not A --> Not B.
If we are told that daily news-watching causes depression, we cannot conclude that people who avoid the daily news are happy.
However, if an argument concludes that A --> B, this conclusion can be strengthened by showing that Not A --> Not B.
If an argument concludes that daily news-watching causes depression, this conclusion can be strengthened by showing that avoiding the daily news causes the depression to disappear.

Hi Mitch,
I hear you here...It clarifies things.

Just a quick clarification required on your above quote -

As for GMAT CR, the KEY DIFFERENCE between the RED part in your above quote and the rest of this quote appears to be that the RED part holds TRUE only as a NON-CONCLUSION portion of a CR ARGUMENT.

Did I get you right ?

RBBmba@2014 wrote:Hi Verbal Experts,
Why Option E is wrong ?

I think, it raises concern about the study and in a GMAT CR in which conclusion is based on some sort of study, then that conclusion, I guess, can be weakened by raising concern about the study. Isn't it ?

GMATGuruNY wrote: If E is true, then the study showed the following:
The more social contact people report, the better their mental skills when performing tasks akin to mathematics problems.

RBBmba@2014 wrote:

GMATGuruNY wrote: If E is true, then the study showed the following:
The more social contact people report, the better their mental skills when performing tasks akin to mathematics problems.

Hi GMATGuruNY,
Don't understand the above part, especially the RED portion...How we can derive at this explanation from the Option E ?

GMATGuruNY wrote: ↑

Wed Jul 15, 2015 2:54 am

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.