小议logical reasoning Bible

cathycathyhan

第一部分：argument的结构
     这个只是我个人的一个总结罢了，如果有不对的地方，希望大家给我指出来。
     1、一般传统的argument结构是，premise-premise-conclusion,或者premise-premise-premise-conclusion。这类结构比较容易认识，一般最后一句话就是结论，或者由于一些像hence,therefore等单词引导。
比如：  Vague laws set vague limits on people’s freedom, which makes it impossible for them to know for certain whether their actions are legal. Thus, under vague laws people cannot feel secure.
  这个结构就是：premise: vague laws set vague limits on people's freedom
             premise: which makes it impossible for them to know for certain whether their action are legal
             conclusion: thus, under vague laws people cannot feel secure.
       还有就是一种是四句式的，第一句往往给你介绍一个事物的背景。
比如：  The retina scanner, a machine that scans the web of tiny blood vessels in the retina, stores information about the pattern informed by the blood vessels. This information allows it to recognize any pattern it has previously scanned. No two eyes have identical patterns of blood vessels in the retina. A retina scanner can therefore be used successfully to determine for any person whether it has ever scanned a retina of that person before.
       这里，premise 1：the retina scanner, a machine that scans the web fo tiny blood vessels int he restina, stores information about the pattern informed by the blood vessels.就是介绍背景的。这样的结构很多，往往是第一句介绍某个理论或者一些人对于某件事情的看法，基于什么原因，然后陈述的是另外一批人发现了新的、不一样的理论，然后得出不同的结论。
比如：  Marine biologists have long thought that variation in the shell color of aquatic snails evolved as a protective camouflage against birds and others predators. Brown shells seem to be more frequent when the underlying seafloor is dark-colored and white shells more frequent when the underlying seafloor is light-colored. A new theory has been advanced, however, that claims that shell color is related to physiological stress associated with heat absorption. According to this theory, brown shells will be more prevalent in areas where the wave action of the sea is great and thus heat absorption from the Sun is minimized, whereas white shells will be more numerous in calmer waters where the snails will absorb more heat from the Sun's rays.
    个人感受：这类结构非常容易找到conclusion,往往最后一句句子就是整个argment的结论，因为关注了结论，这类题目在assumption/strengthen/weaken类型的题目中很容易辨别和得出正确的答案。
     2、几种特殊的argument结构：
    （1）结论在首句：这类题目一般有3个完整句子组成，有时候还有四个句子组成。特点是结论在首句，不容易辨别，如果结论辨别错了，会影响对于整个argument的理解。
     比如： The current pattern of human consumption of resources, in which we rely on nonrenewable resources, for example metal ore, must eventually change. Since there is only so much metal ore available, ultimately we must either do without or turn to renewable resources to take its place.
     这个argument的结论就是首句，既有限定从句，又有插入语，结论是人类现代消耗资源的模式最终会逐步的改变。premise是由一个since连接的因果关系，其中ultimately we must either do without or turn to renewable resources to take its place既是一个premise,还是一个subsidiary conclusioin，它充当了2个角色。
    比如有一例子：
    Pedigreed dogs, including those officially classified as working dogs, must conform to standards set by organizations that issue pedigrees. Those standards generally specify the physical appearance necessary for a dog to be recognized as belonging to a breed but stipulate nothing about other genetic traits, such as those that enable breeds originally developed as working dogs to perform the work for which they were developed. Since dog breeders try to maintain only those traits specified by pedigree organizations, and traits that breeders do not try to maintain risk being lost, certain traits like herding ability risk being lost among pedigreed dogs. Therefore, pedigree organizations should set standards requiring working ability in pedigreed dogs classified as working dogs.
   The phrase “certain traits like herding ability risk being lost among pedigreed dogs” serves which one of the following functions in the argument?
      A. It is a claim on which the argument depends but for which no support is given.
      B. It is a subsidiary conclusion used in support of the main conclusion.
      C. It acknowledges a possible objection to the proposal put forth in the argument.
      D. It summarizes the position that the argument as a whole is directed toward discrediting
      E. It provides evidence necessary to support a claim stated earlier in the argument.
   这道题目中，since后面逗号的这句也是一个subsidiary conclusion,这类结构比较复杂，往往需要关注。
    （2）句子只有两句，但是第一句句子往往非常长和难懂。这类结构看懂复杂的那句是关键，不是让你推断两句句子的关系就是问你他们中缺的东西。
    比如： People who have specialized knowledge about a scientific or technical issue are systematically excluded from juries for trials where the issue is relevant. Thus, trial by jury is not a fair means of settling disputes involving such issues.
    再如：The two newest employees at this company have salaries that are too high for the simple tasks normally assigned to new employees and duties that are too complex for inexperienced workers. Hence, the salaries and the complexity of the duties of these two newest employees should be reduced.

cathycathyhan

第二部分  一些小词的注意
    1、注意一些情态动词和一些表达可能的语句，往往有must、should 、would、can等。表达可能性的词和表达陈述一般事实的句子有所不同，比如I might visit that store和I will visit that store，第一个是表示可能，第二个句子是表达一个即将发生的时间。
  比如看看这道题目的一个错误选项：
  Vague laws set vague limits on people’s freedom, which makes it impossible for them to know for certain whether their actions are legal. Thus, under vague laws people   cannot feel secure.
The conclusion follows logically if which one of the following is assumed?
(B) If people do not know for certain whether their actions are legal, then they might not feel secure.
这里might not代替了cannot，我们觉得这个没有什么大不了，可是bible中的解释是他们的语气程度不一样，can在韦氏词典里是be able to 或者make it possible, might的语气更加婉转，韦氏词典也说 as a polite alternative to may ，所以选项B错了。如果把B的选项改成：If people do not know for certain whether their actions are legal, then they can not feel secure.

cathycathyhan

语气的强弱不仅体现在我们熟知的语气强弱词上，而且还体现在一些短语中或者argument的叙述中，这些叙述的手法有时候我们不是很熟悉。
比如：Flavonoids are a common component of almost all plants, but a specific variety of flavonoid in apples has been found to be an antioxidant. Antioxidants are known to be a factor in the prevention of heart disease.
Which one of the following can be properly inferred
from the passage?
(B) Flavonoids are essential to preventing heart
disease.
(D) At least one type of flavonoid helps to prevent
heart disease.
这里看到选项中的essential是个非常强烈的词语，如果原文中有这个强烈的表达，可以进行这个选择，但是原文中是说to be a factor in 只是一个因素而已，没有说是主要因素，所以我们不能选择essential,而选项D中help to和be a factor in 表达的是同一个程度，而且help to 是原文的改写，一般改写的选项都是正确的选项。
个人体会：需要注意的一些词比如表达重要性的essential, important或者表达数量的most, some, at least one，表达强弱语气的can, cannot, may, may not, will, would等，表达否定的none, never, no等。

cathycathyhan

第三部分：各个题型分析argument的部位

1、第一个家族中的must be、main point、point at issue、method of reasoning、flaw in reasoning、parallel reasoning和第四家族的cannot be true是需要看全部的argument。
（1）其中，must be 和cannot be true两个类型做法有相同的地方，当然也有不同的地方，相同的地方是看这类argument的时候，每个完整的句子都是一个statement，需要从每个句子完整的推出答案，不能只顾premise或者conclusion，而且推出的must be 或者cannot be true在原文中一定有依据。
比如， The increasing complexity of scientific inquiry has led to a proliferation of multiauthored technical articles. Reports of clinical trials involving patients from several hospitals are usually coauthored by physicians from each participating hospital. Likewise, physics papers reporting results from experiments using subsystems developed at various laboratories generally have authors from each
laboratory.
If all of the statements above are true, which one of the following must be true?
答案(B) Most reports of clinical trials involving patients from several hospitals have multiple authors.和它对应的是第二句句子Reports of clinical trials involving patients from several hospitals are usually coauthored by physicians from each participating hospital。LSAT的出题人连词都对的很工整，usually对照most,coauthored对照multiple authors，只能说LSAT绕了2个弯把正确答案给改写了。
再看一个例子：
Sharks have a higher ratio of cartilage mass to body mass than any other organism. They also have a greater resistance to cancer than any other organism. Shark cartilage contains a substance that inhibits tumor growth by stopping the development of a new
blood network. In the past 20 years, none of the responses among terminal cancer patients to various therapeutic measures has been more positive than the response among those who consumed shark cartilage.
If the claims made above are true, then each of the following could be true EXCEPT:
答案: (A) No organism resists cancer better than sharks do, but some resist cancer as well as sharks.也是可以找到原文的出处，They also have a greater resistance to cancer than any other organism.这个说明鲨鱼的cartilage比任何组织抗癌功能要有功效，所以不可能有别的组织和鲨鱼的功效是一样的，这里也是绕了2个弯。不同的是must be true是正确的选项，cannot be true是选不可能的情况。
（2）main point和must be的区别，这个bible中有个章节专门强调了，意思是main point一定是must be true的，但是概况的意思比must be true来的全面，比如，He is a good boy but he likes to eat a lot.这句意思表达了两层意思，当让你阐述main point的时候，需要把两层意思都表达出来，但是must be true可以是he is not a bad boy或者he likes to eat a lot。等问题是问你main point的时候，一定选那个概况全面的，有的答案可能是must be true的情况，但是概况了一部分，这个就不能选。
（3）method of reasoning和point at issue的类似部分，这个类似的部分argument一般是两个人对话，A表达第一个观点，B表达第二个观点，method of reasoning问你B是用何种方式来回答A的，point at issue问你是他们相同的观点在哪里，不同的观点又在哪里。
（4）method of reasoning是需要分清整个argument的结构的，也是我前面说的argument结构的几种。
（5）flaw in the reasoning中，Bible列举了很多错误的方式，我觉得这个部分是需要背的，不仅是flaw in the reasoning中有用，对于其他的形式的argument中错误答案的样子也是有帮助的。
其中，比如第一种uncertain use of a term or a concept，出题中有些错误答案也是如此，比如一个题目原文中说，those people who regularly drink two or three alcoholic beverages a day and thereby exceed the caloric intake necessary to maintain their weight do not in general gain weight，错误的答案说Some people who regularly drink two or three alcoholic beverages a day avoid exceeding the caloric intake necessary to maintain their weight by decreasing caloric intake from other sources.看出来没有，错误的答案中添加了一个avoid和原文截然相反的意思。还有一道题目是说孩子和父亲用的是厨房中的rolling pins，而有个答案是说厨房用具kitchen utensils，显然厨房用具的范围比某个特定厨房产品大很多，这也是bible中说用scope去排除选项的一脉相随的精神。
还有，其中的一个错误是exceptional case/overgeneralization样本不能代表总体或者从个案中概括过度，比如有个例子说，3/4的律师工作很幸苦，那么结论是所以的律师工作都很幸苦，为什么错？因为样本不具有代表性，
最后想提到的一个错误是false analogy就是类比错误，这个方法也是assumption证明的一个方法，记得一个例子是A说一个理论是经济学原理的，然后把这里理论运用到天文学上，然后问你这个题目的assumption是什么？Assumption是两个物体的类比关系，如果要削弱的话，也是两个类比关系中的不同，要加强也是这两个类比关系的共同性。
2、第二个家族是assumption/weaken/strengthen/justify/resolve the paradox。这类家族我觉得还是很有难度的。
（1）个人感觉这类家族中读argument的重点是conclusion，如果你可以找到conclusion中的因果关系，很容易排除错误的选项，因为你找到了关键词。
比如：Eva: A “smart highway” system should be installed, one that would monitor areawide traffic patterns and communicate with computers in vehicles or with programmable high way signs to give drivers information about traffic congestion and alternate routes. Such a system, we can infer, would result in improved traffic flow in and around cities that would do more than improve drivers' tempers; it would decrease the considerable loss of money and productivity that now results from traffic congestion.

Luis: There are already traffic reports on the radio. Why would a “smart highway” system be any better?
Eva's argument depends on the assumption that
A. on “smart highways” there would not be the breakdowns of vehicles that currently cause traffic congestion.
B. traffic lights, if coordinated by the system, would assure a free flow of traffic
C. traffic flow in and around cities is not now so congested that significant improvement is impossible
D. the type of equipment used in “smart highway” systems would vary from one city to another.

E. older vehicle could not be fitted with equipment to receive signals sent by a “smart highway” system
我们可以看到这个argument的结论是such a system, we can infer, would result in improved traffic flow in and around cities that would do more than improve drivers' tempers; it would decrease the considerable loss of money and productivity that now result from traffic congestion.然后根据这个conclusion我们可以发现只有C符合这个结论所描述的情况，正确答案也是C。个人认为这个方法可以用在时间不够的情况下，这样的思路可以提供正确率和提高做题速度。weaken/strengthen也可以用这个方法。
（2）resolve the paradox这类型的问题和assumption/weaken/strengthen有所不同，第一是思路不同，assumption可以看conclusion，但是这类题目不行，因为有的题目就是没有conclusion，然你自己补充的，解决这类题目需要注意：
第一，surprising low/high rate of success，这类型的题目一般是说明事物有的复杂性。
第二，add the facts，比如有一道题目，是说工厂用了新方法去解决操作失误，
但是新方法培训后，工作的操作失误率还往上升，问你解释的原因，答案是因为只有工厂的人数达到很大规模才能开展这类培训，那由于基数多，所以失误率是上升的。
这类题目，个人感觉有点像新旧对比Newer + Older = Total amount,文中或出现2个元素，解释的答案中会出现第三个元素，还有的像 sales * amount= total profit的感觉。

cathycathyhan

第四部分：正确答案的模样

1、在must be/cannot be true的选项中：
（1）重新改写的答案-Paraphrased Answers：Paraphrased Answers are answers that restate a portion of the stimulus in different terms. Because the language is not exactly the same as in the stimulus, Paraphrased Answers can be easy to miss. Paraphrased Answers are designed to test your ability to discern the author’s exact meaning. Sometimes the answer can appear to be almost too obvious since it is drawn directly from the stimulus.
（2）组合的答案： Answers that are the sum of two or more stimulus statements (Combination Answers) Any answer choice that would result from combining two or more statements in the stimulus will be correct. The correct answer to the flavonoid question earlier in this chapter is an excellent example of this idea in action.

第五部分：错误答案的模样

1、在must be的选项中：

（1）有可能正确的选项-can be true or likely to be true:这类选项有可能对，但不是绝对的。

（2）夸大的选项-exaggerated answers:这类选项往往范围过大，和原文不符。比如说：some software vendors,答案会变成most software vendors，还比如Recent advances in the field of molecular biology make it likely that many school textbooks will be rewritten，答案变成Many school textbooks about molecular biology will be rewritten，这里把make it likely给省去了，结果意思全变了。

（3）新元素的选项-new element answer:答案中有新元素是非常有意思的一件事情，在must be 中出现新元素，那一定是错误选项，还有在cannot be 中出现的新元素很多时候也是需要好好推敲的。在assumption/weaken/strengthen/justify/resolve the paradox等类型出现新元素，那就有可能是对的，在以assumption为代表的类型题目，新元素视为整个argument的一部分。

（4）帽子戏法的选项-shell game ：这类选项往往张冠李戴，把A的特性用到了B中去，A和B在argument中都出现过。这类错误选项也是整个logical reasoning出现频率最多的选项中，有时候还利用相似的概念来偷梁换柱，比如dropout rate变成dropout student或者highest dropout rate，这些都需要格外注意的。

（5）相反的答案-opposite answers:这类选择在assumption中可能起到作用，但是在must be 题目中会增强或者削弱题目。

（6）因果关系倒置的选项-reverse answers:比如A导致了B,选项中是B导致了A，这类选项往往和原文中的用词语句都很相似，但是里面的因果关系弄反了。

2、在main idea的选择中：

（1）选项有悖于作者观点的-Answers that are true but do not encapsulate the author’s point.

（2）选项是片面的或者只是重复假设条件的-Answers that repeat premises of the argument.

3、在method of reasoning的选择中：

（1）新元素的选项-new element answer:由于method of reasoning是一个高度概括的题目，所以很多选项都是很抽象，但是会出现一个新元素。

（2）半对半错的选项-half right, half wrong.

（3）夸大的选项-exaggerated answer:

（4）相反的选项-opposite answer

（5）因果关系倒置的选项-reverse answer

比如：

Garbage in this neighborhood probably will not be collected until Thursday this week. Garbage is

usually collected here on Wednesdays, and the garbage collectors in this city are extremely reliable.

However, Monday was a public holiday, and after a public holiday that falls on a Monday, garbage

throughout the city is supposed to be collected one day later than usual.

The argument proceeds by

(A) treating several pieces of irrelevant evidence as though they provide support for the conclusion

(B) indirectly establishing that one thing is likely to occur by directly ruling out all of the alternative possibilities B就是一个半对半错的选项，one thing is likely to是对的，all of the alternative possibilities就是错的，文中没有讲所有的可能性。

1. providing information that allows application of a general rule to a specific case
   
   
   

1. generalizing about all actions of a certain kind on the basis of a description of one such action D选项就是过度概括的选项，也是一个因果倒置的选项，文中是总体到一个应用例子，它说反了，而且D的语言也不符合argument的语气，all action说法过于极端。
   
   
   

(E) treating something that is probable as though it were inevitable. E选项是夸大的选项，没有说inevitable不可避免的，文中只是说supposed to be有可能罢了。

4、在point at issue选择中:

（1）合乎道德和事实的选项-ethical vs factual situation:比如两个讨论一战，一个说是1910年，一个说是1914年，那point at issue是一战的具体时间，而不是一战的参与国有哪些。

（2）双方都同意或者双方都不同意的选项-dual agreement or dual disagreement,比如双方讨论一种食用油里含有危害人体健康的物质，但是A说替代品可以杜绝这类物质危害健康，B说这类食用油里的物质含量没有肉类里的含量高，就算有替代品，人类还是会从别的渠道吸入这类危害物质的，那他们双方讨论的是食用油，但是真正的意思是替代品是不是一个有效的方法杜绝人类吸入这类危害物质。双方涉及的话题，但是不一定是整个argument的焦点所在，有时候只是“影子”部分。

（3）一方不能肯定的选项，就是argument中一方没有具体表达观点的错误选项。

比如：Lea: Contemporary art has become big business. Nowadays art has less to do with selfexpression than with making money. The work of contemporary artists is utterly bereft of spontaneity and creativity, as a visit to any art gallery demonstrates.

Susan: I disagree. One can still find spontaneous, innovative new artwork in most of the smaller, independent galleries.

Lea’s and Susan’s remarks provide the most support for holding that they disagree about whether

(B) most galleries contain some artwork that lacks spontaneity and creativity

(D) some smaller art galleries still exhibit creative new artwork

我当初选了B，我的思路是双方都出现了spontaneity and innovative/creativity的意思，我想那Susan是不同意Lea的大观点，但是在Susan回答Lea中，并没有她的具体表达，而是说了小画廊可以找到一些原创的和新颖的作品。

另外，在point at issue中解法有两种思路：一种是双方很直接的就某个观点提出不同看法，然后找两个人对话的共同点就可以了，还有一种思路是，一方提出一个观点，另一方没有表达整个事物的看法，就表达了自己的不同观点，这个时候只要看后者的不同观点就是正确选项。

cathycathyhan

第六部分：选项出现新元素的问题

选项出现新元素的问题，即new element在选项中，哪些需要注意的：

1、在must be true、main idea、method of reasoning、point at issue中出现，必定是错误的答案。

2、在assumption、weaken、strengthen、justify、resolve the paradox中出现，可以认为是对于argument的补充，应该细细考虑，很多情况都是正确答案。

第七部分：可以预测答案和不能预测答案

可以预测答案的题型是：must be true、cannot be true、 main idea、method of reasoning、point at issue、 flaw in the reasoning、assumption中的supporter题型、resolve the paradox中surprising low/high success的题型。

不可以预测答案的题型是：weaken、strengthen、 justify、assumption中的defender题型、resolve the paradox中的其余题型、parallel reasoning、evaluate the argument的几种题型，不过不可预测的题型中，weaken/strengthen/justify/assumption可以关注conclusion，parallel reasoning可以推导出模式，evaluate the argument出题人往往从premise入手，其实这些还是可以有路可循的。

第八部分：新旧对比argument

我自己觉得这类题目是很容易错的。新旧对比题目其实需要三个元素：新元素、旧元素和总量，这个和销售额、卖出产品的数量和销售利润是一个模子里的题目。

一般，新+旧=总量；

销售额×卖出的产品数量=总的利润

凡是看到这类题目中的两个元素，马上需要想到第三个元素的存在。

比如：

Beverage company representative: The plastic rings that hold six-packs of beverage cans together

pose a threat to wild animals, which often become entangled in the discarded rings and suffocate as a result. Following our lead, all beverage companies will soon use only those rings consisting of a new plastic that disintegrates after only three days’ exposure to sunlight. Once we all complete the switchover from the old to the new plastic rings, therefore, the threat of suffocation that plastic rings pose to wild animals will be eliminated.

Which one of the following, if true, most seriously weakens the representative’s argument?

这道题目是说新东西替代了旧东西，但是结论是the threat of suffocation that plastic rings，结论是整个旧的和新的加起来，所以很容易认为新的会使威胁野生动物减低，其实是总量能够降低，那weaken的部分必然在old上。

阿朗

谢谢分享。
先顶，再慢慢学习。

斯拉万月fish

顶上

槑castor

楼主好强悍啊。。。。。

给我们这种新手提供那么好的东西！

jessica321

好东西啊！不知道有没其他两本的？