sec１３－１２想了好几天，非常感谢！！再问因果型削弱和充分必要型削弱！！

12.   A researcher studying drug addicts found that, on average, they tend to manipulate other people a great deal more than nonaddicts do. The researcher concluded that people who frequently manipulate other people are likely to become addicts.

Which of the following, if true, most seriously weakens the researcher’s conclusion?

(A) After becoming addicted to drugs, drug addicts learn to manipulate other people as a way of obtaining drugs.

(B) When they are imprisoned, drug addicts often use their ability to manipulate other people to obtain better living conditions.

(C) Some nonaddicts manipulate other people more than some addicts do.

(D) People who are likely to become addicts exhibit unusual behavior patterns other than frequent manipulation of other people.

(E) The addicts that the researcher studied were often unsuccessful in obtaining what they wanted when they manipulated other people.

答案Ａ．我没有疑问．我想问Ｄ．以前ＮＮ说Ｄ错因为没有针对结论：manipulate（因）--->addicts（果）　我就是不明白，Ｄ怎么不能理解为无因有果的削弱呢？　

类似的：

137. A study of marital relationships in which one partner's sleeping and waking cycles differ from those of the other partner reveals that such couples share fewer activities with each other and have more violent arguments than do couples in a relationship in which both partners follow the same sleeping and waking patterns. Thus, mismatched sleeping and waking cycles can seriously jeopardize a marriage.

Which of the following, if true, most seriously weakens the argument above?

(A) Married couples in which both spouses follow the same sleeping and waking patterns also occasionally have arguments than can jeopardize the couple's marriage.

(D) People in unhappy marriages have been found to express hostility by adopting a different sleeping and waking cycle fro m that of their spouses.

Ａ：我也不明白．Ａ作为无因有果的削弱为什么不行？

我觉得这两题都是lawyer理论中的因果型削弱吧？那么，结论Ａ－－>Ｂ，非Ａ－－－>Ｂ的削弱是成立的呀．　

而充分必要型削弱：结论Ａ－－－>Ｂ．削弱为：Ａ成立的情况下，Ｂ不成立．非Ａ－－－＞Ｂ不能作为充分必要型的削弱．但这题并不是充分必要型削弱．

第一题D肯定不对，因为D无关，讨论的焦点在manipulate，而D说addict行为异常，是无关干扰项。

137题答案是D吧。

137题A是无关项。因为我们讨论的是睡姿与婚姻关系的问题。而A去扯什么arguments，明显是无关项。

楼主的问题是不能有效的分辩无关项。

做为这类因果题，削弱因的最好的方法，就是证明这个因有可能是果。换句话讲，就是把现象和原因颠倒了。

谢谢楼上的解答．

可是我还是觉得１２的Ｄ不能简单的归为无关．unusual behavior patterns 就是非因，而become addicts 就是果．　无因有果的削弱，怎么不对了？

我打个比方来说明这个问题吧：

比如研究者说：拉肚子的人是因为多吃苹果造成的（这个多吃苹果是研究者观察的结果）

D的意思就是：拉肚子的人除了吃苹果以外，还锻炼身体，学人家做老大什么的。

那D对结论就没有影响了，对不对，没有办法削弱它。

你提的这个例子可以够成削弱．请看ＯＧ１４６

Firms adopting “profit-related-pay” (PRP) contracts pay wages at levels that vary with the firm’s profits. In the metalworking industry last year, firms with PRP contracts in place showed productivity per worker on average 13 percent higher than that of their competitors who used more traditional contracts.

If, on the basis of the evidence above, it is argued that PRP contracts increase worker productivity, which of the following, if true, would most seriously weaken that argument?

(A) Results similar to those cited for the metal-working industry have been found in other industries where PRP contracts are used.

(B) Under PRP contracts costs other than labor costs, such as plant, machinery, and energy, make up an increased proportion of the total cost of each unit of output.

(C) Because introducing PRP contracts greatly changes individual workers’ relationships to the firm, negotiating the introduction of PRP contracts in complex and time consuming.

(D) Many firms in the metalworking industry have modernized production equipment in the last five years, and most of these introduced PRP contracts at the same time.

(E) In firms in the metalworking industry where PRP contracts are in place, the average take-home pay is 15 percent higher than it is in those firms where workers have more traditional contracts.

According to choice D, many firms with PRP contracts also have modernized equipment. Since the cause of their improved productivity might be the modernized equipment, not the PRP contracts, this weakens the argument, so D is the best answer.

前几天见到lawyer大N的一个回帖, 很有启发. 削弱因果有4种方法:

1) 有因无果2)有果无因 3) 它因 4) 因果调转

og 146和og 12题不完全相同

og 12题中说 上瘾的人还表现出别的异常方式，希望以此来削弱控制欲理论。

og 146题说，那此获得的企业在contracts的同时，也同时进行了工业现代化。

我们来分析，

工业现代化是有可能获利的因素

行为异常的人容易吸毒　

（这两个因素的逻辑性）我们用反向推演法来界定它的逻辑

因为获利所以进行工业现代化是对的吗？不太符合常识。。。

因为吸毒所以行为异常是对的吗？基本正确，符合常识。。。

那换句话讲：

行为异常会吸毒，吸毒会导致行为异常。这进入了循环论证(如果不引入第三个要素的情况下)。

那说明，这个逻辑演绎得有问题，对不对？

换句话讲，D答案的错，深究起来是因为它本身的逻辑是不能被推演为合理方式的存在，所以，我们认为它是错的，不知楼上的楼上兄台理解了吗？

至于楼上说加不加only的原则，我认为加上only也是不对的，呵呵。一孔之见：）