标题: OG蓝书中的一道逻辑题，求好心人解惑！ [打印本页] 作者: Christine2099 时间: 2010-11-12 09:24 标题: OG蓝书中的一道逻辑题，求好心人解惑！ 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 hign 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 assumption ?
A. High immune-system activity protects against mental illness better than normal immune-system activity does. B. Mental illness is similar to physical desease 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.
答案是D。可是我觉得一个也对不上号，D加上题目里的experiment能推出conclusion吗？求好心人解答，谢谢！作者: sdcar2010 时间: 2010-11-12 09:49
This is a typical puzzle of correlation and causation. If event A and event B happend together, there are several possible scenarios: A causes B; B causes A; a third event C causes both A and B.
In the question your posted, it is a necessary assumtion. If you use negation method on answer D, you will get: Mental illness DOES cause people's immune-system activity to decrease. If that is the case, then the conclusion that the immune system protects against mental illness does not hold. Hence, answer D is required for the original conclusion.作者: zhijingya 时间: 2011-2-22 22:43
楼上讲的很清晰，但我不明白为什么，Mental illness DOES cause people's immune-system activity to decrease，会weaken the conclusion that the immune system protects against mental illness作者: zhijingya 时间: 2011-2-22 22:44
还有没有别的解释呢作者: sdcar2010 时间: 2011-2-23 08:19
楼上讲的很清晰，但我不明白为什么，Mental illness DOES cause people's immune-system activity to decrease，会weaken the conclusion that the immune system protects against mental illness
-- by 会员 zhijingya (2011/2/22 22:43:57)
Simple.
If mental illness causes people's immune-system activity to decrease，then the conclusion that the immune system protects against mental illness is wrong, isn't it?