[求助]LSAT-17-3-4

原题如下，不明白为什么选D，怎么觉得哪个都对呀

4. The Theory of military deterrence was based on a simple psychological truth, that fear of retaliation makes a would-be aggressor nation hesitate before attacking and is often sufficient to deter it altogether from attacking. Clearly, then, to maintain military deterrence, a nation would have to be believed to have retaliatory power so great that a potential aggressor nation would have reason to think that it could not defend itself against such retaliation.

If the statements above are true, which one of the following can be properly inferred?

(A) A would-be aggressor nation can be deterred from attacking only if it has certain knowledge that it would be destroyed in retaliation by the country it attacks.
(B) A nation will not attack another nation if it believes that its own retaliatory power surpasses that of the other nation.
(C) One nation's failing to attack another establishes that the nation that fails to attack believes that it could not withstand a retaliatory attack from the other nation.
(D) It is in the interests of a nation that seeks deterrence and has unsurpassed military power to let potential aggressors against it become aware of its power of retaliatory attack.
(E) Maintaining maximum deterrence from aggression by other nations requires that a nation maintain a retaliatory force greater than that of any other nation.

首先搞清Stimulus中包含的Argument

Premiss:

The Theory of military deterrence was based on a simple psychological truth, that fear of retaliation makes a would-be aggressor nation hesitate before attacking and is often sufficient to deter it altogether from attacking.

Conclusion:

Clearly, then, to maintain military deterrence, a nation would have to be believed to have retaliatory power so great that a potential aggressor nation would have reason to think that it could not defend itself against such retaliation.

其次要搞清前提和结论的逻辑含义。

这样一个论证其结论其有效性实际上是基于前提与结论之间的Semantically Relation，也就是说，Conclusion is Semantically implied by Premiss；具体点，fear of retaliation是military deterrence的基础，这意味着前者对于后者是必要的；同样，be believed to have retaliatory power so great that….对于fear of retaliation而言是必然蕴含的（对于我们都不相信其存在的东西，谈不上害怕；当然，“害怕”鬼神的跟这里的“害怕”不是同一回事），因此，它同样对于maintain military deterrence 而言是必要的。简而言之，如果A对B是必要的，并且B对C也是必要的，那么A对C同样也是必要的。

我们再看选项。

（A）实际上是说，(a nation’s) knowledge that it would be destroyed in retaliation是deterring a country from attacking的必要条件；原文中唯一与此相关的是结论：“to believe” necessarily means “to have certain knowledge of” 但是，很遗憾，我们从结论只能得出这样的推断：

to maintain military deterrence, a nation would have to make a would be aggressor have certain knowledge of its having retaliatory power….

换而言之，我们只能断定(a nation’s) knowledge that it would be destroyed in retaliation对于maintain military deterrence而言是必要的。如果我们要从结论得出（A），我们必须假设这样的命题：

to maintain military deterrence is the only way to deter a would-be aggressor nation from attacking.

而这是得不到相应的支持的，因为它至少要排除其它可以deter a would-be aggressor from attacking的手段。因此，（A）是错误选项。

（注意，我们说（A）是错的，是就其作为一个选项而言；至于（A）包含的命题或信息，我们无法断定，而题目要求我们选正确答案，因此选项（A）是错的；这并不等于说我们断定（A）这个命题是错的；同样，如果题目要求选错误答案，这样的选项也不能选。这一点，千万要注意！）

（B）实际上讨论的是另一个话题, different though subtly:整个Stimulus涉及的是如何阻止潜在的进攻者进攻,而(B)却在大谈要不要进攻别人。

（C）是有相当的迷惑性的。原文中与此相关的同样只有结论。如果我们要从结论推出（A），我们不但要假设military deterrence is the only way for deterring a wold be aggressor from attacking，还要假设a nation that fails to attack another nation is a potential aggressor，因为原文所有关于military deterrence 的讨论都是限定于a would-be aggressor nation的。

以下是推理过程：

Since, making a potential aggressor aware that a would-be attacked nation has retaliatory power is necessary for maintaining military deterrence;

and,

Maintaining military deterrence is the only way to stop a would-be aggressor from attacking; (assumption)

Therefore

Making a potential aggressor aware that a would-be attacked nation has retaliatory power is necessary for deterring a would-be aggressor from attacking.

That means,

If a would-be aggressor fails to attack another, that establishes that the would-be aggressor believes that it could not withstand a retaliatory attack from the other nation.

到这里，很明显，除非我们再假设：all nations failing to attack another are would-be aggressor nations，否则我们得不出选项（C）的。

这两个假设得不到任何支持！因此，（C）也是undetermined，进而选项（C）也不是正确选项。

（D）是正确选项。它同样是Semantically Implied 。原文的结论说了，….be believed to have a retaliatory power so great….对于maintain military deterrence而言是必要的；同样，“be believed to have a retaliatory power so great….”必然地蕴含着这样的命题“such a retaliatory power is awared by a potential aggressor nation”(对于我们没有意识，感知到的东西，我们怎么去相信呢？)因此，我们可以得出结论

making sure that a potential aggressor nation aware of retaliatory power is necessary for maintaining military deterrence.

如果我们照搬原文结论的格式，则是

….to maintain military deterrence, a nation would have to make a potential aggressor nation aware that it has such retaliatory power.

而选项（D）只不过是对这样的命题的另一种说法而已：既然一个国家要maintain military deterrence，而making a potential aggressor nation aware of its retaliatory power对于这样的目标是必要的，那么它对于有这样的目标的国家而言当然是利害攸关的（it is in the interest of ….）

（E）同（B）一样转移了论题，因此我们无法加以断定：对于maximum retaliatory power以及如何实现它的问题原文没有相关的信息，原文讨论的是retaliatory power与military deterrence的关系。

综观本题，我想有几点要注意：

第一，     此题及正确答案的逻辑结构。

此题实际上围绕着要的一个论证结构：如果A对B而言是必要的，B对C是必要的，而C对D同样是必要的，那么A对D同样是必要的；倒过来者是：如果D必然意味着C，C意味着B，而B同样必然意味着A，那么D同样意味着A。

本题的论证，加上正确选项是这样一个过程：

the fear of a retaliation by a potential aggressor nation is necessary for maintaining military deterrence;

a potential aggressor’s fear of a retaliation necessarily implies that the aggressor believes that the would-be attacked nation has a retaliatory power;

therefore,

making a potential aggressor nation believe that it has the retaliatory power is necessary for a country who wants to maintain military deterrence.

equally,

since a country’s believing that another nation has a retaliatory power necessarily implies that it is aware of that nation’s possession such a retaliatory power,

making a potential aggressor aware that it has such a retaliatory power is necessary for a nation who wants to maintain military deterrence.

这样的论证大家想必不陌生，“我思故我在”就是这样的结构：我能肯定我正在思考，我正在思考必然意味着我存在，因此，我存在。（当然，如果从哲学的角度考虑，结合印欧语系的独特结构，笛卡尔的这个论证是有循环论证的嫌疑的，但这不在我们考虑的范围了）

第二，         要注意命题的断定范围。选项（A）（C）是很有迷惑性的；但是如果我们能够始终注意到maintain military deterrence与deterring a would-be aggressor from attacking以及sufficient conditional statement与necessary conditional statement之间的区别的话，那他们将不构成困难。

第三，在逻辑思考时，永远要注意“true（probable）”“false(improbable)”“undetermined”这三种可能。特别是“undetermined”大家很容易与“false”搞混。思维起源于对未知的敬畏呀！