请教两个ff logic题目

小饼子

21. Historian: We can learn about the medical history of individuals through chemical analysis of their hair. It is likely, for example, that Isaac Newton’s psychological problems were due to mercury poisoning; traces of mercury were found in his hair. Analysis is now being done on a lock of Beethoven’s hair. Although no convincing argument has shown that Beethoven ever had a venereal disease, some people hypothesize that venereal disease caused his deafness. Since mercury was commonly ingested in Beethoven’s time to treat venereal disease, if researchers find a trace of mercury in his hair, we can conclude that this hypothesis is correct.


Which one of the following is an assumption on which the historian’s argument depends?


A.None of the mercury introduced into the body can be eliminated.
B.Some people in Beethoven’s time did not ingest mercury.
C.Mercury is an effective treatment for venereal disease.
D.Mercury poisoning can cause deafness in people with venereal disease.
E.Beethoven suffered from psychological problems of the same severity as Newton’s.


There should be 2 assumptions to support the hypothesis. The 1st assumption of the author is that only venereal disease will be treated by mercury in Beethoven’s time. The 2nd assumption is only some people in Beethoven's time will ingest mercury, if all people ingest mercury, the evidence is not useful. So, some people in Beethoven's time did not ingest mercury. The answer should be B.
My Question:给的解释中第一个assumption能够理解。第二个实在想不通，求解析哟！

27. These days, drug companies and health professionals alike are focusing their attention on cholesterol in the blood. The more cholesterol we have in our blood, the higher the risk that we shall die of a heart attack. The issue is pertinent since heart disease kills more North Americans every year than any other single cause. At least three factors---smoking, drinking, and exercise—can each influence levels of the cholesterol in the blood.


Which one of the following can be properly concluded from the passage?


A.If a person has low blood cholesterol, then that person’s risk of fatal heart disease is low.
B.Smoking in moderation can entail as great a risk of fatal heart disease as does heavy smoking.
C.A high-cholesterol diet is the principal cause of death in North America.
D.The only way that smoking increases one’s risk of fatal heart disease is by influencing the levels of cholesterol in the blood.
E.The risk of fatal heart disease can be altered by certain changes in lifestyle.


答案是E。解释：

A.原文中说，胆固醇越高，生心脏病的可能性越大。A选项的内容是否命题，不一定成立。

My Question: A这个选项很confused，是说所有的这种类型的命题只要反过来说都是不正确的吗？
THX

小饼子

Thank you soooooooooooo much!

sdcar2010

27. These days, drug companies and health professionals alike are focusing their attention on cholesterol in the blood. The more cholesterol we have in our blood, the higher the risk that we shall die of a heart attack. The issue is pertinent since heart disease kills more North Americans every year than any other single cause. At least three factors---smoking, drinking, and exercise—can each influence levels of the cholesterol in the blood.


Which one of the following can be properly concluded from the passage?


A.If a person has low blood cholesterol, then that person’s risk of fatal heart disease is low.
B.Smoking in moderation can entail as great a risk of fatal heart disease as does heavy smoking.
C.A high-cholesterol diet is the principal cause of death in North America.
D.The only way that smoking increases one’s risk of fatal heart disease is by influencing the levels of cholesterol in the blood.
E.The risk of fatal heart disease can be altered by certain changes in lifestyle.


答案是E。解释：

A.原文中说，胆固醇越高，生心脏病的可能性越大。A选项的内容是否命题，不一定成立。

My Question: A这个选项很confused，是说所有的这种类型的命题只要反过来说都是不正确的吗？
THX

If one argument is true, simply exchanging an arugment's sufficient and necessary conditions would not guarantee the accuracy of the new statement.  Only contrapositive statement is guaranteed to be true.

sdcar2010

21. Historian: We can learn about the medical history of individuals through chemical analysis of their hair. It is likely, for example, that Isaac Newton’s psychological problems were due to mercury poisoning; traces of mercury were found in his hair. Analysis is now being done on a lock of Beethoven’s hair. Although no convincing argument has shown that Beethoven ever had a venereal disease, some people hypothesize that venereal disease caused his deafness. Since mercury was commonly ingested in Beethoven’s time to treat venereal disease, if researchers find a trace of mercury in his hair, we can conclude that this hypothesis is correct.


Which one of the following is an assumption on which the historian’s argument depends?


A.None of the mercury introduced into the body can be eliminated.
B.Some people in Beethoven’s time did not ingest mercury.
C.Mercury is an effective treatment for venereal disease.
D.Mercury poisoning can cause deafness in people with venereal disease.
E.Beethoven suffered from psychological problems of the same severity as Newton’s.


There should be 2 assumptions to support the hypothesis. The 1st assumption of the author is that only venereal disease will be treated by mercury in Beethoven’s time. The 2nd assumption is only some people in Beethoven's time will ingest mercury, if all people ingest mercury, the evidence is not useful. So, some people in Beethoven's time did not ingest mercury. The answer should be B.
My Question:给的解释中第一个assumption能够理解。第二个实在想不通，求解析哟！

This is an old LSAT question.  For the second hypothesis, if EVERYONE in Beethoven's time ate mercury as a daily supplement, then simply based on the fact that mercury is found in Beethoven's hair, we cannot conclusively say he ate the mercury to cure his disease because he might very well ate mercury as a daily supplement. Therefore we have to have the second assumption for the arugment to hold.