陈向东逻辑P57-Q47

Exports of United States wood pulp will rise considerably during this year. The reason for the rise is that the falling value of the dollar will make it cheaper for paper manufacturers in Japan and Western Europe to uy American wood pulp than to get it from any other souce.

Which of the following is an assumption made in drawing the conclusion above?

A. Factory output of paper products in Japan and Western Europe will increase sharply during this year.
B. The quality of the wood pulp produced in the United States would be adequate for the purposes of Japanese and Western European paper manufacturers.
C. Paper manufacturers in Japan and Western Europe would prefer to use wood pulp produced in the United States if cost were not a factor.
D. Demand for paper products made in Japan and Western Europe will not increase sharply during this year.
E. Production of wood pulp by United States companies will not increase sharply during this year.



答案为A，请问C为什么不对

You have to know what assumption is. It is a required condition, without which the argument will not hold. For example: Man needs to eat --> Pete needs to eat. That Pete is man is the assumption. If this assumption is not true, the argument would not hold.

Test C yourself. If C is not true, will the argument still hold?

Agree,  (B) is the argument's assumption.

对C取非，为“if costs were not a factor, Japan and Western Europe would not prefer to use wood pulp produced in USA”，那么当然原命题（If wood pulp from USA is cheaper, the exports will rise）不成立，没看出哪里有问题

反倒A不如C这么直接，因为A讲的是quality（原文没有提及，选项应该有附加解释将quality与原文关联起来）而C直接讲cost，更加相关

C取非之后是没有对结论起到削弱作用的，“如果价格不是一个因素，日本和西欧国家不会优先使用美国产的纸浆”，但现在的情况是，美国纸浆比其他国家的便宜了，这样，价格就成为了一个考虑因素，所以日本和西欧国家就可能使用美国产的纸浆了——没有削弱结论。

对B（不是A）取非，“美国产的纸浆不符合日本和欧洲造纸厂的质量要求”，这样即使美国纸浆的价格便宜，日本和欧洲造纸厂也可能不会采用，这样就削弱了“美国产纸浆出口量将上升”的结论。