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immune-system activity

Expert replies
by Uri » Fri Apr 03, 2009 7:19 am
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.

OA: [spoiler](D)[/spoiler]

Although the OA is very much reasonable, the sudden appearance of "physical disease" in the last sentence forces me to give (B) a good consideration. Can you please justify why (B) should not be the answer?
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Source: — Critical Reasoning |

by thought » Fri Apr 03, 2009 7:40 am
My rephrasing of the argument:

Because low immune activity patients have lower mental health scores than normal/high activity patients, the immune system protects against mental illness as well as against physical disease.

A. This is wrong because the low is compared to normal/high in the argument. (High is not compared to normal.)

B. I see your point but this is out of scope (the body effects are irrelevant to the argument). A quick way to test is to negate. If the argument depends on an assumption, when you negate the assumption the argument should fall apart.

Even if "Mental illness is NOT similar to physical disease in its effects on body systems" the argument still holds up.

C. Out of scope.

D. If we negate, "Mental illness causes people’s immune-system activity to decrease" then the argument's conclusion is flawed because it illness causes low immune activity, rather than low immune activity causing illness. So this assumption is necessary for the argument to hold up.

E. Irrelevant

Does this help?
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by kris77 » Fri May 13, 2016 10:34 pm
My intuition whispers that it is A.
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