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标题: 请教一个一个GMAT逻辑思路-是否因果对结果否就错呢？ [打印本页]

作者: nadianshide 时间: 2014-8-13 09:14
标题: 请教一个一个GMAT逻辑思路-是否因果对结果否就错呢？
Helr的逻辑中说，如果是因果型题目，那么对结果进行否定并不能削弱逻辑链本身。比如你身上有酒味，所以你今天喝酒了。你说，我没喝。这是没有用的，因为你没有否定我的推理链。
但狒狒逻辑中很多都是对结果进行否定的正确答案。比如下面这题：

20. A rise in the percentage of all 18-year-olds who were recruited by the armed services of a small republic between 1980 and 1986 correlates with a rise in the percentage of young people who dropped out of high school in that republic. Since 18-year-olds in the republic are generally either high school graduates or high school dropouts, the correlation leads to the conclusion that the republic’s recruitment rates for 18-year-olds depend substantially on recruitment rates for high school dropouts.

Which one of the following statements, if true, most weakens the argument?
(A) A large number of 18-year-old high school graduates were recruited for the republic’s armed services in 1986 than in 1980.
(B) Many of the high-technology systems used by the republic’s armed services can be operated only by individuals who have completed a high school education.
(C) Between 1980 and 1986 the percentage of high school graduates among 18-year-olds recruited in the republic rose sharply.
(D) Personnel of the republic’s armed services are strongly encouraged to finish their high school education.
(E) The proportion of recruits who had completed at least two years of college education was greater in 1986 than in 1980.

答案C 这应该是对结果否吧，只是说这个比例没有高，但没有指出原题逻辑推理哪里有错。狒狒中有很多类似的题目。

我在想，那么针对Helr所说的，你身上有酒味所以你喝酒了。那如果有个选项是'我没喝"或者“我意识很清醒，所以我没喝”（他因？）算对吗？可是这两个选项都没有指出原逻辑链的错误在哪里，只是自己又提出了一个新的来啊？

还请各位大牛指教啊啊啊~TOT

ps 小女此处第一次发帖，也不知道标签对不对哈, 大家见谅~

作者: nadianshide 时间: 2014-8-14 10:39
自己小顶一下~

作者: zzx576122628 时间: 2014-8-20 22:19
A rise in the percentage of all 18-year-olds who were recruited by the armed services of a small republic between 1980 and 1986 correlates with a rise in the percentage of young people who dropped out of high school in that republic. Since 18-year-olds in the republic are generally either high school graduates or high school dropouts, the correlation leads to the conclusion that the republic’s recruitment rates for 18-year-olds depend substantially on recruitment rates for high school dropouts.

样本推断
样本：1980到1986年，18岁征兵（小国）比例的上升与青少年辍学比例上升相关
结论：全国征兵比率主要取决于青少年辍学征兵比例
削弱
说明样本不具备代表性或者样本数量不足，选项一定提及样本

Which one of the following statements, if true, most weakens the argument?
(A) A large number of 18-year-old high school graduates were recruited for the republic’s armed services in 1986 than in 1980. （这题比较级去哪儿了

目测是larger，1986比1980人多智能说明真的rise了不能说明样本数量足够或者样本具有代表性）
(B) Many of the high-technology systems used by the republic’s armed services can be operated only by individuals who have completed a high school education. （没提到样本）
(C) Between 1980 and 1986 the percentage of high school graduates among 18-year-olds recruited in the republic rose sharply. （样本特殊，不具有代表性，即样本提到的事儿不是常态）
(D) Personnel of the republic’s armed services are strongly encouraged to finish their high school education. （没提到样本）
(E) The proportion of recruits who had completed at least two years of college education was greater in 1986 than in 1980.（跟A一样，提到样本数量的变化但是没用）

另外不建议楼主做狒狒逻辑，建议只做官方题目，OG,PREP,GWD足够

作者: zzx576122628 时间: 2014-8-20 22:21

nadianshide 发表于 2014-8-14 10:39
自己小顶一下~

忘记点回复。。。

作者: nadianshide 时间: 2014-8-20 22:28

zzx576122628 发表于 2014-8-20 22:19
A rise in the percentage of all 18-year-olds who were recruited by the armed services of a small rep ...

啊谢谢谢谢~大概理解了。

狒狒的题目是怪了一点。还有一周就考试了所以果断扔之~回归OG

作者: zzx576122628 时间: 2014-8-20 22:46

nadianshide 发表于 2014-8-20 22:28
啊谢谢谢谢~大概理解了。狒狒的题目是怪了一点。还有一周就考试了所以果断扔之~回归OG ...

9.3号考，前天晚上见到这个方法，现在在一**用了，觉得这个方法一定能做对但是真的好慢啊。。。。sigh

作者: nadianshide 时间: 2014-8-20 22:54

zzx576122628 发表于 2014-8-20 22:46
9.3号考，前天晚上见到这个方法，现在在一**用了，觉得这个方法一定能做对但是真的好慢啊。。。。sigh ...

哈哈我也是才看到这个神方法，不过呢我觉得这种归类逻辑只能稍微把自己带上路，上路之后就不要去纠结这些逻辑类型了，有的时候做多了自己就能猜出来OG的思路呢。重点还是脑洞要尽量贴近OG哈哈哈哈~
那一起加油~

作者: zzx576122628 时间: 2014-8-20 23:17

nadianshide 发表于 2014-8-20 22:54
哈哈我也是才看到这个神方法，不过呢我觉得这种归类逻辑只能稍微把自己带上路，上路之后就不要去纠结这些 ...

共勉咯~我还有好多都不会呢~加油吧~

作者: sunyuwei 时间: 2014-10-18 11:55
我认为可以用相关因果来做，高新兵招募率的他因->有高中生被招募就是C的选项===

作者: 三塘木 时间: 2014-10-18 21:30
Helr的逻辑中说，如果是因果型题目，那么对结果进行否定并不能削弱逻辑链本身。比如你身上有酒味，所以你今天喝酒了。你说，我没喝。这是没有用的，因为你没有否定我的推理链。
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我还没看题目，但是楼主对于因果和果因的概念错了。你身上有酒味，是我观察到的现象，然后根据我的观察我给出结论 “所以你喝过酒了”，这个是很明显的果因关系。对于果因关系，果是绝对不会被动摇的，质疑的要么是果和因之间的直接关系“有酒味和喝过酒没有直接关系”，要么可以有他因“我聚会的朋友身上有酒味，所以我沾染了他们身上的酒味（但是我没喝酒）”，在这里提出“我没喝酒”是可以的，同时你要最好提出具体的原因你没喝酒（因）怎么才能解释身上有酒味（果）。这里你不能说“我身上没有酒味，你鼻子有问题”，因为攻击果在这里是不能证明你的逻辑的。因为果是已经被观察到的事实现象，而我们所有的讨论都是在前提是“你身上有酒味”之下进行的讨论，如果连这个前提都没有了的话，那么讨论也就没有实际意义了。
同样的针对因果关系，你去喝酒了（因），所以你身上会有酒味（果），这是我根据我对你的行为的事实做出的一种结果假设，针对因果关系，ＣＱ要么是证明因果没有关系，有酒味和喝过酒没有直接关系，或者有其他的干扰因素，我喝的酒是特殊酒不会让我有酒味。在这里如果你直接回应说“我没有去喝酒”（在vivian的一篇帖子里提到说这可以也算是干扰因素，但是我个人觉得这是对因的直接否定，否定了前提“你去喝酒了”，但是对证明果是不是可靠的推测完全没有帮助。同样的，如果这个前提都没有了的话，这个就没有讨论意义了。

因果和果因里面，直接攻击前提（因果里的“因”，果因里的“果”）是没有用的，要论证的话需要攻击里面的逻辑链（因果相关性），或者攻击里面的结论（因果里的“果”，果因里的“因”）

作者: 三塘木 时间: 2014-10-18 21:32
20. A rise in the percentage of all 18-year-olds who were recruited by the armed services of a small republic between 1980 and 1986 correlates with a rise in the percentage of young people who dropped out of high school in that republic. Since 18-year-olds in the republic are generally either high school graduates or high school dropouts, the correlation leads to the conclusion that the republic’s recruitment rates for 18-year-olds depend substantially on recruitment rates for high school dropouts.

Which one of the following statements, if true, most weakens the argument?
(A) A large number of 18-year-old high school graduates were recruited for the republic’s armed services in 1986 than in 1980.
(B) Many of the high-technology systems used by the republic’s armed services can be operated only by individuals who have completed a high school education.
(C) Between 1980 and 1986 the percentage of high school graduates among 18-year-olds recruited in the republic rose sharply.
(D) Personnel of the republic’s armed services are strongly encouraged to finish their high school education.
(E) The proportion of recruits who had completed at least two years of college education was greater in 1986 than in 1980.

再来看题目，用helr的方法来做的话：
１找结论和前提：
结论：
republic’s recruitment rates for 18-year-olds depend substantially on recruitment rates for high school dropouts
前提：
A rise in the percentage of all 18-year-olds who were recruited by the armed services of a small republic between 1980 and 1986 correlates with a rise in the percentage of young people who dropped out of high school in that republic

２看推理模式：我们可以看出来，原题作者把参军率和退学率两个不相关的事情放在一起，时间发生的一致，然后发现了两个有正相关关系，所以推断出参军率和退学率相关。这个很明显是相关因果类的题。相关因果的题是和因果果因完全不同的，相关因果是涉及到了两个变量（这里一个自变量Ｘ退学率一个因变量Ｙ参军率），然后判断说两者在pattern上有正相关，所以推测出ＸＹ是相关的。
针对相关因果类，ＣＱ有四个，因果相关性不存在，第三因素，中间因素和因果方向问题。在这道题的选项里，只有Ｃ是直接攻击了因果相关性的问题，证明说高中毕业的学生参军率也有急速上升，并不是说一定是退学率的上升导致的参军率上升。
希望这个能有帮助

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