The conclusion of the argument is that alcohol addiction increases a person’s susceptibility to life-threatening diseases, reducing life expectancy. To support this conclusion, the argument relies on the statistics that a higher percentage of alcoholics die before the age of 75 compared to non-alcoholics.
We need to find an assumption that the argument depends on. The assumption must be something that is necessary for the conclusion to be valid but is not explicitly stated in the argument. Let's evaluate each option:
(A) People who are predisposed to life-threatening diseases are more likely than other people to become alcoholic.
This option suggests that there is a correlation between having a predisposition to life-threatening diseases and becoming an alcoholic. However, this assumption introduces an alternative explanation for the correlation between alcoholism and shorter life expectancy. This weakens the argument rather than supporting it because if people who are already predisposed to diseases are more likely to become alcoholics, it would not be alcoholism causing the reduced life expectancy. Therefore, this is not a necessary assumption.
(B) The statistics cited exclude deaths due to other alcohol-related events such as automobile accidents.
This is a strong contender. The argument is about life-threatening diseases, but if the statistics include deaths caused by alcohol-related accidents (like car accidents), then the conclusion would be invalid because it would attribute deaths from accidents to diseases. To maintain the argument's focus on life-threatening diseases, it is necessary to assume that deaths from alcohol-related accidents are excluded.
Therefore, this is a necessary assumption.(C) Alcoholism does not also increase a person’s susceptibility to diseases that are not life-threatening.
The conclusion focuses on life-threatening diseases, and whether alcoholism affects susceptibility to non-life-threatening diseases is irrelevant to the argument. Therefore, this is not a necessary assumption.
(D) The life expectancy of that portion of the general population not characterized by alcoholism increases over time.
The conclusion is about the effect of alcoholism on life expectancy relative to non-alcoholics. This option talks about the life expectancy of non-alcoholics increasing over time, which does not directly affect the conclusion about the comparison between alcoholics and non-alcoholics at the present time. Therefore, this is not a necessary assumption.
(E) The author of the report is not biased in his or her personal opinion about the morality of alcohol consumption.
The personal bias of the author does not impact the validity of the statistical comparison and the conclusion drawn from it. Whether the author has a moral opinion about alcohol consumption is irrelevant to the assumption that the conclusion depends on. Therefore, this is not a necessary assumption.
Conclusion:The best answer is (B) because it provides a necessary assumption that the statistics focus on deaths due to diseases rather than alcohol-related accidents. Without this assumption, the argument would not hold.