标题: GMAT 逻辑分析题 (14) [打印本页] 作者: sdcar2010 时间: 2010-11-23 11:18 标题: GMAT 逻辑分析题 (14) Recently discovered prehistoric cave paintings on Diaoyu Dao, or Uotsuri Jima in Japanese, have archaeologists puzzled. The traditional theory about these cave paintings was that they were mostly a description of the favorite diets of the prehistoric painters. This “diet” theory cannot be right, because these painters must have needed to eat the animals populating the East China Sea if they were to make a living on the island and to sail across the East China Sea, but there are no paintings that distinctively depict these sea creatures in the cave.
Each of the following statements, if true, weakens the argument against the traditional theory about the cave paintings EXCEPT:
a) While living on the island, the cave painters hunted, caught, and ate land animals. b) A significant part of the original cave paintings on the islands were lost during a tsunami. c) The cave paintings that were recently discovered on the islands pictured many land animals. d) The cave painters learned the Chinese traditional method of how to preserve meats. e) These cave paintings on the island were completed by the original islanders who ate the meat of farmed land animals.作者: 梦离ouzi 时间: 2010-11-23 12:00
D吧。Since they had learned the chinese traditional method implies that they must have made a living on the island and had sailed across the East China Sea. Hence, statement D supports the argument against the theory.作者: sdcar2010 时间: 2010-11-23 12:08
This is a tricky question. You need to read the question prompt to know CLEARLY which theory or argument to support or weaken.作者: fielcy 时间: 2010-11-23 12:12
Is that right to choose D which is irrelevant?
BTW, it is so surprise to know that you made up those questions by yourself. awesome~作者: kevin0214 时间: 2010-11-23 12:33
P( live on the island and sail across Sea)， Q(eat sea creature)，X(paintings depict sea creature)，Y(we see these paintings) IF P,THEN Q, IF Q, THEN X, IF X, THEN Y 原文考古学家给出的是Q和X的关系，如果考古学家是正确的，则Q→X。 现在已知非Y，原文ARGUMENT说因此Q推不出X。这个论证很弱，因为这条链那么长，很多地方都可以用来解释非Y的发生。 A表达: P推不出Q，可以解释非Y； B表达：X推不出Y，可以解释非Y； D表达：P推不出Q，可以解释非Y； E表达：非P，可以解释非Y。
答案选C，没有表达任何关于这个推理链的东西。作者: kevin0214 时间: 2010-11-23 12:36
这题很有意思，要写出来才完全弄清这个链条，特别是考古学家的解释和题目的argument到底在什么地方有抵触我想了挺久。作者: sdcar2010 时间: 2010-11-23 12:52
Very nice logic chain! C is the only irrelevant answer choice among the five. The other all weaken the author's argument.
Good job, Kevin.作者: 梦离ouzi 时间: 2010-11-23 12:57
好难啊。。下次要乖乖拿起笔来分析了。If these questions were to appear on gmat it would take quite long to figure out. 你们好聪明唉。作者: fielcy 时间: 2010-11-23 13:05
看题目太草率了 看来我逻辑还得有待加强 期待楼主的更多的题目 作者: efrenreyes 时间: 2010-11-23 22:14
楼上的没有一个是正解，不过答案确实是C。各位热烈的讨论，加深了我此前就有的一个判断，即人的逻辑能力主要是先天决定的，并且很难通过学习得到加强。后天的训练，很大程度上只是帮助你在处理你先天逻辑能力本就可以胜任的问题时，可以更加地熟练，表现在做题上就是速度会更快。但是，不会让你拥有你原本并不具备的处理复杂逻辑推理的能力，在应对该类问题时，你的推理依然会是漏洞百出的，尽管你仍然有可能会象这题一样，在多个选项中恰好蒙对答案。
好比这题的X → Q还是Q→X，一般人容易弄混（但这恰恰反映了你最原始的逻辑能力）。可能你认为二者是充要条件（暂且假设考古学家是对的），但是其实二者并不是，因为painters也可以Q(eat sea creature)，但仍然“非”X(paintings depict sea creature)，如果sea creature不是favorite diets of the prehistoric painters的话，则考古学家的假设仍然是对的。
原文试图用"there are no paintings that distinctively depict these sea creatures" ，基于"painters must have needed to eat the animals populating the East China Sea"这个假设，去argue against 考古学家的假设。注意按照题意"there are no paintings that distinctively depict these sea creatures" ，已经是一个客观事实，不容否认。那么要weaken the argument ，可以从以下几个方面入手：
1、weaken "painters must have needed to eat the animals populating the East China Sea" "if they were to make a living on the island "，这只是个假设，是可以weaken的。比如选项A，如果the cave painters hunted, caught, and ate land animals成立，那么假设就直接被weaken了，因为painters caught and ate land animals，因此不是must have needed to eat the animals populating the East China Sea；同理，选项E也直接weaken了该假设；
2、weaken "painters must have needed to eat the animals populating the East China Sea" " if they were to sail across the East China Sea" 。比如选项D，因为painters learned how to preserve meats，因此不是must have needed to eat the animals populating the East China Sea when they were sailing across the East China Sea；
3、指出原题"there are no paintings that distinctively depict these sea creatures"这个客观事实不全面，不具代表性。比如选项B，如果"A significant part of the original cave paintings on the islands were lost"成立，则"there are no paintings that distinctively depict these sea creatures"这个事实不全面，因为可能有大量的paintings that distinctively depict these sea creatures were lost；
4、选项C并不是无关选项，"paintings that were recently discovered on the islands pictured many land animals"具体化了"there are no paintings that distinctively depict these sea creatures"这个原题中已经给出的客观事实，那么如果考古学家的假设是对的，则 X(paintings depict land animals) → Q(painters eat land animals as favorite diets ) ，与原题所提出的"painters must have needed to eat the animals populating the East China Sea"(暗示sea creatures 才应该是 painters' favorite diets）的假设相悖。
综上，选项C是题设所求正确答案。
p.s.写了以上这么多，不是为了打击任何人，又或者炫耀什么。对于个人而言，做逻辑题是准备GMAT考试最有乐趣的一个部分（数学实在太过简单了），因此非常乐意把推理过程拿出来和大家分享。我之所以费力打了这么多字，是希望大家明白一个道理，逻辑能力是很难后天加以提高的，与其把时间和精力投入在边际产出如此小的一个方向上，实在不如多背背单词和语法，毕竟这些东西是死的，可以通过后天机械的训练和记忆大幅予以提高。作者: sdcar2010 时间: 2010-11-23 23:51
Hehe, I will write a review later.作者: kevin0214 时间: 2010-11-24 03:11
首先对efrenreyes对我逻辑漏洞的指出表示感谢！我很认真地拜读了您的回帖，并且对其中Q和X的解释很认真地思考了一遍，the favorite diets 和the food they ate的区别我并非没有看出来（当然我这样事后诸葛亮显得很假），但是后面的题干和选项中都没有关于favorite和unfavorite的比较，所以我自以为用the food they ate的意思带替代就足以判断答案了，当然事实证明这样会产生逻辑错误，这是我的失误，也谢谢efrenreyes指出。 原本按照原文的意思the food was their favorite diets 和paitings depict the food是充要条件，但是我把the food was their favorite diets换成the food they ate之后，就只能从paitings depict the food推出the food was what they ate而不能反过来推了，这就是我的错误，也是efrenreyes指出的。 如果哪位同学被误导了，我在此道歉。
不过，我对efrenreyes提出的第4点不能同意。 “那么如果考古学家的假设是对的，则 X(paintings depict land animals) → Q(painters eat land animals as favorite diets ) ，与原题所提出的"painters must have needed to eat the animals populating the East China Sea"(暗示sea creatures 才应该是 painters' favorite diets）的假设相悖。” 为了不辜负efrenreyes兄的长篇大论为我指出错误，我也花些时间写足够的篇幅来阐述我的思考。鉴于我的英文一般，用中文来表达，如果与原意有什么出入，请指正。 这篇题目的结构是这样的： （1）一个事实：岛上有画，画上没有海产（后面都用“鱼”表示）。 （2）一个假说：画者画的是他们最喜欢的食物。 （3）一个包含推理的反驳：如果画者住在岛上并且来自中国东海岸，则他们必定要吃东海里的鱼。现在事实上画上没有鱼，所以这个假说（画者画的是他们最喜欢的食物）是错误的。 我们的任务是削弱这个反驳。 第一点，efrenreyes兄的第4比较费解，不过既然认为C不是无关，同时又是正确选项（非削弱），那么唯一的可能是加强。怎么加强的呢？我确实是看了几遍才理解的，我反应慢没办法。efrenreyes兄认为：在C（最新发现的洞穴画画了很多陆生动物）的条件下，如果考古学家是对的，则推出一个与原题中反驳者相悖的结论Q（画者把陆生动物当作最喜欢的食物），——以下是我补充的内容，我想efrenreyes要表达的是这个意思，也是我唯一想得到的C作为加强项的合理解释，请跳过破折号读—— 所以Q不可能是对的，所以考古学家的理论也是错的（已知C为真，Q为假，则C→Q这个推理有误）。所以C通过证明考古学家的理论错误支持了反驳者的论证。 但是这个解释本身是有问题的。在证明Q的错误时，这个解释（通过表达与它相悖的观点Q错误）假设了反驳者的理论是正确的，这就造成了一个循环论证，通过假设某个观点正确，然后得出结论来支持这个观点。 第二点，即使Q(painters eat land animals as favorite diets) 为真，与原题所提出的"painters must have needed to eat the animals populating the East China Sea”有何相悖之处？“画者最喜欢的食物是陆生动物”和“画者必须吃鱼” 有任何相悖之处吗？如果我每天必须吃米饭，那我最喜欢吃的就必须是米饭？ 第三点， efrenreyes兄本想用来解释第二点提出的问题，就是括号中的“暗示sea creatures 才应该是 painters' favorite diets” 。“画者必须吃那些生活在中国东海中的水产”如何暗示了他们最喜欢吃的是海产？同样是米饭的比喻，必须吃跟喜欢吃显然没有推理关系。
为何我认为C选项是无关呢？GMAT的无关指的是没有对我们考虑的“目标论证”有增强或者削弱的作用。注意上面对题目的分析，我们考虑的论证是哪一个呢？是对假说的那个反驳：“如果画者住在岛上并且来自中国东海岸，则他们必定要吃东海里的鱼。现在事实上画上没有鱼，所以这个假说（画者画的是他们最喜欢的食物）是错误的” 而C项给出的内容是：最近发现的洞穴画里有很多陆生动物。这个无关是非常明显的，它没有给出任何支持或者削弱这个论证的信息。 以上是我对题目本身的分析，如果还有什么错误，欢迎大家指正。 最后，我想说，谢谢efrenreyes提醒了我，天外总是有天的，人外总是有人的。我一开始也以为我的答案已经没有问题了，很高兴，不过听你一说回头想想还是有不少没有想到的东西。很荣幸我们几个人的讨论坚定了你内心的信念，这也算一个对他人的小小贡献吧。 但是对于“人的逻辑能力主要是先天决定的，并且很难通过学习得到加强”的说法，我并不同意，不过请恕我不准备为我的不同意列举理由了。我想一个人不接受未经严格论证过的理论应该是可以理解的吧？我尊重别人内心的belief，因为有些东西属于信仰范畴，自己接受不需要逻辑论证，但是一个接受过逻辑训练的人接受别人的belief之前应该先严格仔细地考察他的论证，我想这应该是大家都可以理解的。 抛开信念的不同，其实逻辑能力是否能够通过后天提高并不影响大家在这里的讨论，就算逻辑能力无法提高，也不意味着GMAT的逻辑分数无法提高，后者可能才是大家讨论的直接目的，至于在这个讨论过程究竟逻辑能力提高了没有的问题就算存在分歧又如何？无论人们是否相信上帝和来世，他们都可以行善布施，不是吗？作者: sdcar2010 时间: 2010-11-24 04:26
First, if the way I created this question caused some confusion among readers who tried to find the correct answer, please accept my sincere apology. Second, if the confusion led to your inability to pick the right answer, again, please accept my sincere apology. However, this is simply a weird test question I created, which is akin to a game for those who want to have some fun and is not a litmus test to rank any reader’s intelligence. That said, the following are my original thoughts on how to solve this problem.
Recently discovered prehistoric cave paintings on Diaoyu Dao, or Uotsuri Jima in Japanese, have archaeologists puzzled. The traditional theory about these cave paintings was that they were mostly a description of the favorite diets of the prehistoric painters. This “diet” theory cannot be right, because these painters must have needed to eat the animals populating the East China Sea if they were to make a living on the island and to sail across the East China Sea, but there are no paintings that distinctively depict these sea creatures in the cave.
Each of the following statements, if true, weakens the argument against the traditional theory about the cave paintings EXCEPT:
a) While living on the island, the cave painters hunted, caught, and ate land animals. b) A significant part of the original cave paintings on the islands were lost during a tsunami. c) The cave paintings that were recently discovered on the islands pictured many land animals. d) The cave painters learned the Chinese traditional method of how to preserve meats. e) These cave paintings on the island were completed by the original islanders who ate the meat of farmed land animals.
After reading the stimulus, it is apparent that this is a strengthen/weaken type of question paired with EXCEPT. Therefore, we're expecting four wrong answers among the five answer choices to weaken the argument and one correct answer not to weaken the argument. The correct answer might strengthen or have no impact on the argument.
Before analyzing the answer choices, let’s go over the core of this argument first. According to the stimulus: Premises: 1) There are no sea creatures in the cave paintings. 2) The painters would have needed to eat sea creatures to make a living on the island and to sail across the East China Sea. Conclusion: The paintings were not mostly a description of the favorite diet of the prehistoric painters.
As we learned from working with GMAT logic questions, there are multiple ways to weaken an argument. You can either attack the premises on which the conclusion rests or undermine the conclusion by showing that the conclusion fails to account for some element or possibility. The job we have at hand is to find 4 ways to hurt the argument and eliminate them as wrong answers. The last one left standing would be the correct answer. With this strategy in mind, let’s jump into the answer choices
a) While living on the island, the cave painters hunted, caught, and ate land animals. This statement weakens the argument by suggesting that the diet of the painters included land animals and did not need to include sea creatures. It is an attack on premise 2.
b) A significant part of the original cave paintings on the islands were lost during a tsunami. This statement suggests that the cave paintings we have now are not complete and there might have been paintings depicting sea creatures in the cave. It is an attack on premise 1.
c) The cave paintings that were recently discovered on the islands pictured many land animals. This statement is the correct answer. The author's argument is based on the lack of sea animals. How many land animals are in the paintings has no bearing on his argument. It is irrelevant to the argument.
d) The cave painters learned the Chinese traditional method of how to preserve meats. This statement weakens the argument by removing premise 2 from the consideration. If the preserved meats constitute cave painters’ staple food, they didn't need to eat sea creatures at all.
e) These cave paintings on the island were completed by the original islanders who ate the meat of farmed land animals. This statement weakens the argument by questioning the premise 2 of the argument. It points out that if the painters farmed land animals, they would not have had to eat sea creatures.作者: sdcar2010 时间: 2010-11-24 04:48
Another way to look at the fallacy is the following:
When the author evaluates the following argument --
Premises: A) The cave paintings were mostly a description of the favorite diets of the prehistoric painters. B) The cave painters must have needed to eat the sea creatures.
he reaches the conclusion: C) The cave paintings must depict the sea creatures.
In formal logic, this argument equals to (A + B) -> C
When the author finds out that conclusion C is wrong, i.e., the cave paintings depict no sea creatures, he conluded that the premise A is wrong. In formal logic, this process equates : not C -> not A. However, in formal logic, the correct contrapositive for an argument of (A + B) -> C should be : not C -> either not A or not B. In other word, when the sea creature is not found among the cave paintings, it could be caused by the possibility that the cave painters did not need to eat the sea creatures. Answer choices A, D & E point out this possibility, while answer choice B simply refutes the author's finding of not C.作者: efrenreyes 时间: 2010-11-24 09:37
唉，我就知道我的回复会引起很多人的反感，其实我只是好心劝大家不要浪费太多时间在不可能提高的逻辑能力上面，如果你们不服气，那愿意怎样就怎样吧。我个人教育背景相信和这里的绝大多数同学不太一样，坦白讲，不需要靠打击任何人的逻辑能力，来坚定我内心的信念。可能我们确实都无法理解对方的世界，在我看来，逻辑和数学一样都是送分的题目，根本没有讨论的必要，我回复的主要目的，如前所述，是为了向大家揭示逻辑能力几乎不可能通过后天努力提高的客观事实，而不是真的想和大家讨论怎么解题。GMAT的逻辑题，个人只要看完题，基本就可以立即秒出答案，要全部写下来才能答出答案，个人没试过也从没想过。如果你们认为看逻辑的辅导材料，或者背下如何推理答题的模式思路并不断运用于训练，会对提高成绩有帮助，那就继续吧，祝你们好运！作者: sdcar2010 时间: 2010-11-24 11:14
We all have our own idiosyncratic ways to solve logic problems or to present our view points. After all, this forum would be a void without a thread like this.作者: kevin0214 时间: 2010-11-24 11:32
efrenreyes兄，您终于想开了~圣人何必来屈尊教化我们这些蛮夷呢？ 另，祝您秒杀愉快，希望您的教育背景为您铺就美好未来！作者: fielcy 时间: 2010-11-24 12:46
虽然你逻辑题目或许做的很厉害 可是你现在的想法就犯了逻辑的错误 按你的说法你逻辑能力是与生俱来的那也就是说你自己从没去做过后天的训练，但如果这样你又是如何知道后天训练是没有用的呢？ 或许你看见了一些人在做你自己认为很简单的题目时候犯了错或是绕了圈，你怎么就又知道他们不是初学者，在经过一段时间的训练后就会很厉害，甚至比你厉害呢？
