Critical Reasoning

A researcher discovered that people who have low levels of immune-system activity tend to score much
lower on tests of mental health than do people with normal or high immune-system activity. The researcher
concluded from this experiment that the immune system protects against mental illness as well as against
physical disease.
The researcher’s conclusion depends on which of the following assumptions?
A. High immune-system activity protects against mental illness better than normal immune-system activity
does.
B. Mental illness is similar to physical disease in its effects on body systems.
C. People with high immune-system activity cannot develop mental illness.
D. Mental illness does not cause people’s immune-system activity to decrease.
E. Psychological treatment of mental illness is not as effective as is medical treatment.

Can someone explain how?
D

hemanth28, at first look I took B but with giving a thought I decided to chose D. Now the reason I used is -
Argument says that experiment shows people with low levels of immune-system activity tend to score much lower on tests of mental health than do people with normal or high immune-system activity. So it can directly concluded that immune-system has some effect on mental health. But now look in different perspective. We can also say that the result of the previous experiment was because of mental health but not because of immune-system.
To be very specific/ clear, according to the argument -

Reason -> Effect
Immune-system -> Mental health

But we can also say that -

Reason -> Effect
Mental health -> Immune-system

So doctor should assume the later. So it is D. Got me Hemanth28? But I would like to mention one thing - this Qs should somehow come in tough / harder category - it should not be in easy/hard Qs category.

I did not understand how you concluded the second quote from the first one

hemanth28! U r getting me wrong, man. What I tried to say that the second quote is not a conclusion from the first one but it is an ASSUMPTION. Unless and until the doctors did not assume the second quote they can not draw conclusion like the first one. Be cool! Just think and go thru one again what I have mentioned in my last post. The Qs is not about the CONCLUSION but about the ASSUMPTION. These two are totally different from each other. Let me know if u r still having any doubt!

Hi Amitava,
I agree with ur expln, but in the conclusion it is also mentioned that

concluded from this experiment that the immune system protects against mental illness as well as against
physical disease.

the highlighted part is not supported by the premise, so one may think that the assumption will clarify this pt.

B does that to some extent, what do u say abt that.

Hey Samir! Agree with you man. This Qs, I think, should not come under easy or harder section of the Qs but in the tough level. However, the point is when

the doctor has concluded that the immune system protects against mental illness as well as against physical disease.

But the argument has not said anything about the physical illness but about the mental illness. So we can not take physical illness in our account. In this regard, I would prefer to refer Mainnoi's post. Ohhhh! I have forgot the link! Sorry! :roll: In that post, he mentioned about the points you should take care while attempting a CR. Mainnoi, request u to post link here again.
[Mainnoi, I know I have misspelled your name but hope you understand what I want to say ... ]

thanks amitava..i gotcha...

camitava wrote:Hey Samir! Agree with you man. This Qs, I think, should not come under easy or harder section of the Qs but in the tough level. However, the point is when

the doctor has concluded that the immune system protects against mental illness as well as against physical disease.

But the argument has not said anything about the physical illness but about the mental illness. So we can not take physical illness in our account. In this regard, I would prefer to refer Mainnoi's post. Ohhhh! I have forgot the link! Sorry! :roll: In that post, he mentioned about the points you should take care while attempting a CR. Mainnoi, request u to post link here again.
[Mainnoi, I know I have misspelled your name but hope you understand what I want to say ... ]

Hey man, can you find out that post by Mainnoi that you refer in your post ? I tried the search engine but its not pulling up anything...

Thanks

-TK

Hey TkNeo! I meant mayonnai5e by Mainnoi actually. mayonnai5e, the moderator of verbal section! But sorry man I am not being able to find out the link as well.

camitava wrote:Hey TkNeo! I meant mayonnai5e by Mainnoi actually. mayonnai5e, the moderator of verbal section! But sorry man I am not being able to find out the link as well.

No problem man. Thanks for looking out !

Hi all

I have a quick question on this.

when I negate D, the argument does not fall apart rather it strengthens, so how does the negation principle work in such a question.

while if I negate c, the arg falls apart.

Thanks for help.

apps17 wrote:Hi all

I have a quick question on this.

when I negate D, the argument does not fall apart rather it strengthens, so how does the negation principle work in such a question.

while if I negate c, the arg falls apart.

Thanks for help.

Conclusion: immune system protects against mental illness as well as against physical disease．
Basis of this conclusion: people who have low levels of immune' system activity tend to score much lower on tests of mental health than do people with normal or high immune' system activity.

The problem with C is that it doesn't talk about people with normal immune system activity. It mentions only those with high ISA.

Try negating D: Mental illness causes ISA to decrease - this is a case of reverse causation. It implies that the immune system does not protect against mental disease; rather, mental disease may adversely affect the immune system. Negation questions the basis of the argument. Thus, D is the right answer.