一道答案易混的题(兼论充分型假设题的解法:分析在22楼)

bryan0806

想了好久 选D

一直在看D和E  最后看原文是impossible 而E是require 还要个非

所以不选

lawyer_1

我给这道题的目的有两个：1是说明充分型假设（假设选项，原文结论能合理推出）的TEST（答案检验法）。2是这种题易混的答案。

1。充分型假设的TEST：将选项加入到原文推理中，看看能否推出原文结论。即：正确答案+原文前提=原文结论。

2。这种题最易混的答案为：相反的推理。即变为从结论往前提推。而正确答案常是以逆否命题的面目出现。所以增加了难度。

3。做法：一是找出原文的推理。特别注意从那里推向那里。二是找出推理中的GAP。排除没有这个GAP的概念的选项，剩下常只有两个。看着两个那个是推理相反的选项，排除掉它。剩下的就是正确的。或者用TEST去对，看那个符合TEST。

该题：推理：因为 mathematical proposition NO PROVE BY OBSERVATION， 所以mathematical proposition  IMPOSSIBLE KNOW TO BE TRUE(概念跳跃为PROVE By observation，KNOW)。推理方向从NO PROVE BY OBSERVATION到 IMPOSSIBLE KNOW。（注意：这里没有充分必要关系，即不能将原文写成NO PROVE BY OBSERVQATION---〉IMPOSSIBLE KNOW。）

A：意思为proposition KNOWN TO BE TRUE--->ROPOSITION CAN BE PROVE。该选项很容易混。因为推理方向对：逆否命题从NO PROVE 到IMPOSSIBLE KNOW。且概念也很象，包含和被包含的概念（proposition包含mathematical proposition），概念比原文大在这类题中是允许的。但它错在没有说明PROVE的方式，原文有说明PROVE的方式为BY OBSERVATION。这也是和E选项的唯一区别。所以A选项加BY OBSERVATION便为答案。

B：没有KNOW的概念。错

C：CAN BE PROVE BY OBSERVATION---〉 KNOWN TO BE TRUE。逆否命题为IMPOSSIBLE KNOWN TO BE TRUE--->CANNOT BE PROVE BY OBSERVATION。和原文推理相反。错

D：IMPOSSIBLE KNOWN TO BE TRUE--->CANNOT BE PROVE BY OBSERVATION.和原文推理相反。错。

E：KNOWN TO BE TRUE--->CAN BE PROVE BY OBSERVATION（注意REQUIRE带必要条件）。逆否命题为：CANNOT BE PROVE BY OBSERVATION---〉IMPOSSIBLE KNOWN TO BE TRUE。和原文推理方向一致。正确答案。

注明：该题较特殊。除了两个推理相反的选项。还有一个概念相似的混淆项。

[此贴子已经被作者于2004-11-12 2:21:46编辑过]

hpp920

太佩服了, 希望多看到这样的分析文章!

哎,你是不是真是个lawyer呀? 你的脑袋怎么能够这么清晰!! 逻辑上我都用功快1个月了, 还是木头疙瘩一个! 我要重重的叹口气!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

paopao

终于盼来了lawyer的解答 非常感谢 收获大大的

有几点疑问 继续请教lawyer

1.     推理关系：因为。。。所以。。 没有充分必要关系，我感觉没有什么本质不同。因为下面的选项，用的是充分必要，加上前提，推出结论。

2.     在什么题型中，包含与被包含关系是许可的。因为在一般的演绎题中，要求概念一致，不能扩大的。

3.     两个表达式请教，我的理解对吗？ 我可能搞反了。

(D) Knowing a proposition to be true is impossible only if it cannot be proved true by observation

impossible to know be true -à cannot be prove by observation

Knowing a proposition to be true is impossible unless it cannot be proved true by observation

Know to be true-à  prove true by observation

4．我认为E的概念与原文不一致。 题目要求的是it is possible to know any mathematical proposition to be true 即原文表达的是可能性。而E成为Knowing a proposition to be true 错

lawyer_1

1。我提醒注意的目的是不要搞混充分必要和因果关系。对本题，你是对的。即即使原文为充分必要关系，也对。

2。演绎题从来没有这个说法。倒是归纳题有着说法。典型的是假设题中，答案为大前提。

3。第一对，第二错。应该为Know to be true-à   CANNOT prove true by observation（见充分必要条件指示词）

4。如果Knowing a proposition to be true 。那麽是不是就it is possible to know proposition to be true 。反之则不不对。

paopao

以下是引用lawyer_1在2004-11-12 10:24:00的发言：

2。演绎题从来没有这个说法。倒是归纳题有着说法。典型的是假设题中，答案为大前提。

lawyer: 你讲的其它我已明白了 是我将充分必要搞错了

第2条能否讲讲 总感觉心里没底

可能概念我也搞错了

[此贴子已经被作者于2004-11-12 10:38:29编辑过]

bryan0806

看来我也对充分必要搞错了

我理解(D)Knowing a proposition to be true is impossible only if it cannot be proved true by observation 成

cannot be proved true by observation  ->  Knowing a proposition to be true is impossible

一个问题请教 如果D改成(D)Knowing a proposition to be true is impossible if it cannot be proved true by observation

是不是正确答案 即改后的D可否理解成

cannot be proved true by observation  ->  Knowing a proposition to be true is impossible

lawyer_1

C，D改指示词都可为答案。这也是我给这题的目的。充分型假设的混淆项最多的是将推理搞反。如果大家没从该题明白这点，那这道题的目的就达不到了。

to PAOPAO

第2点我无法给你讲具体。你混得是将大前提推出小前提搞成大概念就能推出小概念。

bryan0806

呵 了解了 解开了长久来心中的疑云

希望lawyer兄能多出点这样的帖子  有趣兼学习！！

paopao

以下是引用lawyer_1在2004-11-12 11:07:00的发言：

第2点我无法给你讲具体。你混得是将大前提推出小前提搞成大概念就能推出小概念。

lawyer:我想把问题搞明白

举个例子

105.

Treatment for hypertension forestalls certain medical expenses by preventing strokes and heart disease. Yet any money so saved amounts to only one-fourth of the expenditures required to treat the hypertensive population. Therefore, there is no economic justification for preventive treatment for hypertension.

Which of the following, if true, is most damaging to the conclusion above?

(A) The many fatal strokes and heart attacks resulting from untreated hypertension cause insignificant medical expenditures but large economic losses of other sorts.

(B) The cost, per patient, of preventive treatment for hypertension would remain constant even if such treatment were instituted on a large scale.

(C) In matters of health care, economic considerations should ideally not be dominant.

(D) Effective prevention presupposes early diagnosis, and programs to ensure early diagnosis are costly.

(E) The net savings in medical resources achieved by some preventive health measures are smaller than the net losses attributable to certain other measures of this kind.

105.

If the results of untreated hypertension cause large economic losses, as choice A claims, then the treatment of hypertension may well be economically justifiable. Therefore choice A is most damaging to the conclusion and is the best answer.

Choices B and D tend to support the conclusion; choice B says that making preventive treatment widespread would not introduce economies of scale,排除另一种可能性，支持 and choice D identifies one aspect of prevention that is both costly and essential.提出另一论据，支持 Choice C undermines a different conclusion-that society should not support treatment for hypertension-but does not damage the conclusion actually drawn. The fact that different preventive health measures have different economic consequences (choice E) gives no specific information about treatment for hypertension, and so cannot affect the conclusion drawn.

我认为选项E就是个大小概念的问题 原文讲的是预防高血压 E讲的是预防疾病 所以OG的解释说这个预防疾病与预防高血压没有关系 无关

这不是说明在演绎题中 概念要一致 不能有大于原文的概念吗

谢谢 真希望能指出我的毛病所在