[求助]紧急问题 assumption, 在线等答复，谢谢！ ：）

juliet01192000

第二遍复习og cr了，真怀疑自己第一遍怎么看的assumption体型。

问一个弱弱的问题：

The official’s conclusion logically depends on which of the following assumptions?

原文结论（X）depends on 假定（选项）（Y）

到底是X--> Y 还是Y---〉X;

感觉推理关系应该是 Y---〉X，

但是看laywer实战方法说：

DENIAL TEST：将选项取非，原文结论不成立，则为正确选项。

即非Y--->非X, 那么按照原来学的数学知识，这应该等价于X--->Y,逆否命题成立。

这与我感觉的推理关系应该 Y---〉X，矛盾。难道我的感觉不对？？？！！！

还是说原文结论（X）depends on 假定（选项）（Y）是X,Y互为充要条件？

不明白。。。逻辑特差。。。

帮忙解疑，谢谢，在线等！：）

jandjshi

X）depends on 假定（选项）（Y） => Y is the necessary condition of X

support: X -> Y, 或非Y -> 非X
weaken: X -> 非Y
assumption: 用Lawyer的办法, 将选项取非，原文结论不成立，则为正确选项。

juliet01192000

谢谢jandjshi ：）

但是作题是怎么想呢，就拿8举例

8. To prevent some conflicts of interest, Congress could prohibit high-level government officials from accepting positions as lobbyists for three years after such officials leave government service. One such official concluded, however, that such a prohibition would be unfortunate because it would prevent high-level government officials from earning a livelihood for three years.

The official’s conclusion logically depends on which of the following assumptions?

A. Laws should not restrict the behavior of former government officials.

B. Lobbyists are typically people who have previously been high-level government officials.

C. Low-level government officials do not often become lobbyists when they leave government service.

D. High-level government officials who leave government service are capable of earning a livelihood only as lobbyists. D

E. High-level government officials who leave government service are currently permitted to act as lobbyists for only three years.

在思考过程中我们会认为原文中有一个gap,选项D正是一个填补这个GAP的新元素。

这样就相当于吧选项D(Y)作为了推导出原文（X）的充分条件，即：Y--->X

这与你上面所说的：X）depends on 假定（选项）（Y） => Y is the necessary condition of X 矛盾。

我的理解那里有错？继续糊涂中。。。

lawyer_1

假设有两类（依问题问法分），充分型（justify the conclusion）和必要型(depend on)。

1。对于充分型，答案为填补GAP的选项，选项既是结论的充分条件之一，又是必要条件之一。

2。对于必要型假设，可以是选项为结论必要条件之一，不是充分条件。用取非法，因为答案为结论必要条件（结论推出选项，逆否命题为取非）。也可以是既是必要条件，同时也是充分条件，就像你说的该题。 可用取非法，但是因为找GAP的办法较容易，所以多数不用取非的办法。

jandjshi

啊, 今天有lawyer大NN答贴, 兴奋ing啊.

jandjshi

害, 看了半天没看懂. 才发现我讲的XY, 同lawyer和juliet讲的XY不是一回事. Lawyer讲的是选项于结论的关系, 我讲的是结论里XY条件的关系.

但奇怪的是, 我怎么看不出OG8有Gap呢? 我觉得就2个条件 X)lobbyist  Y) earning. 作者的conclusion: it (not being a lobbyist) would prevent high-level government officials from earning a livelihood for three years  => 即not being a lobbyist -> no earning => 即being a lobbyist是earning的necessary condition.

D: earning -> being a lobbyist. 作者一定要depend on这条, 才能推出not being a lobbyist -> no earning. 所以用取非的方法.

不知这样理解对不对?

juliet01192000

以下是引用jandjshi在2006-3-31 2:58:00的发言：
啊, 今天有lawyer大NN答贴, 兴奋ing啊.

先表达一下自己同样的激动心情，呵呵，nn lawyer给我回帖了!