lawyer逻辑思路

1、做逻辑题的大体思路做逻辑关键是搞清楚为何对,为何错,看OG的主要目的也在这儿,不在做多少题。第一步:看问题。第二步:看原文,分清结论和支持结论的理由,特别是原文有些信息只是背景知识,不是理由,结论有时也不一定有THEREFORE之类的词,甚至有了这些词,结论也可能和它不一样,搞清结论要结合原文作者要表达的方向和理由支持的方向。第三步:从选项中分清有关无关,留下有关的,去掉无关的。和结论讨论的话题或TOPIC 无关的就是无关。第四步:按不同题型再最后分清正确与错误选项。ASSUMPTION类。一。ASSUMPTION类。假设类分充分型和必要型。充分型是问题问你下列哪个假设,能使原文的结论PROP

2、OERL Y推出。必要型是问题问你原文的推理依赖下列哪个假设。他们的作题思路不同。充分类因为原文结论是必须能从证据推出(加上假设,所以方法较简单,将选项加到原文的推理中,如果结论必成立(MUST BE,则为答案,如果结论有不成立的可能性,则错,其中的特例是原文证据和结论的概念差异(GAP,说出这个GAP就是假设。必要类复杂点,总体的方法是将选项取非,如果原文的结论必不成立,则为答案,如果还有成立的可能性,则错。取非就是假设选项是错的。其中有几种特例。一是其他类(其他原因,可能性。,它的假设是不存在其他(原因,可能。另一种是原文证据和结论的概念差异(GAP,说出这个差异就是假设。还有一种是只考虑

3、单方面,其假设是其他方面没影响。其特例是比较两个东东,只比较某方面,便得出一个总体结论,其假设是其他方面没影响。充分类的加进法和必要类的取非法都可用于TEST所有选项,但因时间较长,所以通常方法是用有关无关排除后剩下难分的选项才用这方法,很多情况下通过有关无关排除便只剩下一个。他们的特例则可以直接找答案。附加信息对原文推理的作用类二。附加信息对原文推理的作用类。该类包括SUPPORT,WEAKEN,EV ALUATION三种。就是找出下列哪个选项对原文的推理能起作用(WEAKEN,SUPPORT或两者都有。它本身有两层意思。一是选项本身或和原文的证据结合对结论起问题所说的作用(支持或作用;多数

4、在这层面上便找到了答案或排除剩下一个。二。并且他们的证明力度比原文单独的证据大或削弱原文的证据证明力,所以简单的重复原文证据(注意:有些正确选项好像重复原文证据,实际是原文证据更强或更弱不是正确选项。这类的正确选项有两种形式:A是提供另外的证据直接支持或削弱结论,这种情况多数是原文的证据只是背景知识,或和原文的结论相关性不大。B是使原文的证据和结论的距离拉近或拉远,使结论的可能性变大或变小,加大或减少原文证据对结论的证明力。这时要特别注意原文证据对结论的证明角度,最难分的选项常在这里做文章。这类题有三种特例可直接找答案:一是其他类(其他可能性,其他原因,特别是原文给个实验或调查,然后得出某个结

5、论,这时WEAKEN的方法常是提供另一种可能性。第二类是只考虑单方面(其中包括比较,WEAKEN的方式是指出这个错误,说有其他方面没考虑。第三类就是直接作用结论。总之这类题的重点在原文的结论。检验正确选项的方法是选项是否使原文的结论正确的可能性更大或更小(和单纯有原文的结论比。类比关于类比,除非阅读量不大,否则,建议猜一个,等有时间再作,类比的关键是将事件当作A,B,。,然后看其抽象后的逻辑。看选项那个抽象后和原文的一样就是答案GAP(逻辑上的跳跃指原文的推理过程中有概念的跳跃,这个跳跃可以存在证据中,也可以存在证据和结论中(该题存在证据和结论中,这两个概念不仅仅内容不同,关键是逻辑上有跳跃,

6、即逻辑上不能从一个推出另一个(在原文的CONTEXT下,如该题的B选项,就是因为能从PRIORIYT 推出NOT INDIFFERNTL Y,所以不存在逻辑上的跳跃。该题讨论见连接关于WEAKEN和SUPPORT的补充想法WEAKEN和SUPPORT的答案一般规律不强,较难把握,这点对出题人也一样,因为又不能出一眼就看清的的弱智混淆项,如果稍不小心又易出了有争议的答案,因为面对的毕竟是是全世界的考生。但是,所谓物极必反,表面无序的东西往往规律明显,也正是很容易就出了有争议的答案,出题人除了用MOST去排除这种可能性之外,必须有个明确的指导思想和界限去区分混淆选项,去指导出混淆选项。这种指导思想

7、就是出相反的选项和与结论的具体性和特殊性无关的混淆选项。所以做这两类题,要特别注意结论的特殊性和具体性,无论如何强调对结论的重视都是不过分的,因为选项最综是作用在结论上。如果一个选项满足了两个条件:方向上了和结论一致(排除相反选项:即问题问支持,给削弱的答案。反之亦然,并且符合结论的特殊性和具体性。这个选项就是正确答案。所以做题时,看原文时要找产生结论的前提和结论,在脑中形成推理结构(因为。所以。,特别是结论,以结论作为有关无关的标准去排除无关相,剩下的再排除相反选项,就找到了答案。假设题如何取非取非意思就是假如某个选项是错的。大体有三种情况:1. all-not all/some-none/

8、always-not always/sometimes-never/everywhere-not everywhere/somewhere-nowhere/only one, exactly one-none, more than one/at least one, some-none2. 对于选项为条件句,将必要条件取非。3. 直接将谓语肯定变否定,或否定变肯定。if you get a high score of GMA T, you will be accepted by Harvard University.取非为:if you get a high score of GMA T, y

9、ou will NOTbe accepted by Harvard University充分必要条件指示词1.introduce a sufficient condition:if/when/whenever/every/all/any/people who/in order to/roduce a necessary condition:then/only/only if/must/require/no,none(在句子开头3.unless equation:unless/except/until/without(其后面部分变成必要条件,其它加NOT变充分条件4.特例:the

10、only way to achieve success is to work hard. achieve success(充分条件only a professional consultant can solve the organizations problems. a professional consultant(必要条件no citizen can be denied the right to vote. denied the right to vote(充分条件. no citizen(必要条件1。denied the right to vote(充分条件no citizen(必要条件

11、。即citizenright to vote (逆否命题,所以ROBERCHU兄说的其实一样,只是原文的逆否命题。不要看丢RIGHT 前还有个DENIED。2。no citizen can be denied the right to vote. denied the right to vote. 即All citizen can NOT be denied the right to vote。即IF citizen,THEN canNOT be denied the right to vote. 即IF citizen,THEN right to vote。1。No A is B=all A

12、 are not B: 实际上这时A和B是两个不相交的圈圈。2。All A are not B=If A, then not B3。同意了上面两点,就能明白原文的那句话。No citizen(Acan be denied the right to vote (B根据1,2。这句话就等于if citizen(A, then not be denied the right to vote(not B。即if citizen(A, then HA VE the right to vote(not B。充分条件是citizen,必要条件是have th right to vote。逆否命题:If be

13、 denied the right to vote, then no citizen。充分条件是be denied the right to vote。必要条件是no citizen。你要从本质,意思去理解,不是有何形式去转换。IF。THEN是充分必要条件的普通方式,以理解,所以才将其他形式的充分必要条件转换为它。它的本质为:A成立,则B一定成立。All A are B.意思为所有A都是B。既然所有A是B。则凡是A的东西,就是B。所以等同于IF A,THEN B因果关系和充分必要关系是完全不同的关系,没有交集。前者是一件事的发生导致另一件事的发生,时间上有先后,没有推理关系。后者是一件事的发生

14、表示另一件事过去,现在或将来的发生,时间没有先后,有推理关系。一道答案易混的题(兼论充分型假设题的解法24. No mathematical proposition can be proven true by observation. It follows that it is impossible to know any mathematical proposition to be true.The conclusion follows logically if which one of the following is assumed?(A Only propositions that c

15、an be proven true can be known to be true(B Observation alone cannot be used to prove the truth of any proposition(C If a proposition can be proven true by observation then it can be known to be true.(D Knowing a proposition to be true is impossible only if it cannot be proved true by observation(E

16、Knowing a proposition to be true requires proving it true by observation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

17、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 NOPROVE 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

18、KNOW。A:意思为proposition KNOWN TO BE TRUE->PROPOSITION 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 B

19、Y 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 KN

20、OWN 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。一道题(兼论如何理解结论One year ago a local government initiated an antismoking advertising campaign in local newspapers which it financed by imposing a tax on cigarettes of 20 cents per pack。One year later the number of people in the locality who

21、 smoke cigarettes had declined by 3 percent。Clearly what was said in the advertisements had an effect,although a small one on the number of people in the locality who smoke cigarettes.Which one of the following, if true, most helps to strengthen argument?(A Residents of the locality have not increas

22、ed their use of other tobacco products such as snuff and chewing tobacco since the campaign went into effect(B A substantial number of cigarette smokers in the locality who did not quit smoking during the campaign now smoke less than they did before it began(C Admissions to the local hospital for ch

23、ronic respiratory ailments were down by 15 percent one year after the campaign began(D Merchants in the locality responded to the local tax by reducing the price at which they sold cigarettes by 20 cents per pack(E Smokers in the locality had incomes that on average were 25 percent lower than those

24、of nonsmokers1。对于SUPPORT,ASSUMPTION和WEAKEN题,要特别重视结论的具体性和特殊性(我在“考试时如何做逻辑题”说过。这就是这几类题排除有关无关的依据,有时单凭这点就排除无关项后只剩答案。结论的具体性和特殊性就是要精确理解结论,理解每部分在原文中的的精确的具体的含义(结合证据,是这意思,不是那意思,是指这个,不是指那个。它是讲个方面的问题,讲的是什麽,具体情况如何。这点无论如何强调都不过分。2。具体到本题,结论是:广告所说的内容有效果。这是在讨论政府的禁烟广告是否有作用,在讲广告对禁烟的作用,它的效果在原文体现在一年后本地人吸烟人数减少3%(证据。这个效果是指

25、抽烟人数减少,不是指别的效果。这就是结论的特殊性和具体性。A。好像是排除他因。但它讲的效果是用别的烟产品的效果,不是抽烟的效果,它讲的是用的频率没有增加的效果,不是吸烟人数减少的效果。故无关B。它讲的是用的量的效果,是程度的效果,不是人数多少的效果。故错C。易排除D。对广告对抽烟人数减少的效果,排除一种可能。即抽烟人数减少有可能是烟太贵了(加税,D排除这种可能,故加强结论。E。没钱,那就别抽烟,没钱又不是发生在广告后。无关。3。其实大家有没有看出结论是因果型结论,结论可说成是:本地政府的广告导致抽烟人数减少3%。因果型结论的支持方式之一是排除其他原因。如果原文的One year later t

26、he number of people in the locality who smoke cigarettes had declined by 3 percent.改为One year later the cigarettes people in the locality smoke had declined by 3 percent.A 还有可能成为答案。请体会这两者区别。对于SUPPORT,ASSUMPTION和WEAKEN题,要特别重视结论的具体性和特殊性(我在“考试时如何做逻辑题”说过。这就是这几类题排除有关无关的依据,有时单凭这点就排除无关项后只剩答案。结论的具体性和特殊性就是要精

27、确理解结论,理解每部分在原文中的的精确的具体的含义(结合证据,是这意思,不是那意思,是指这个,不是指那个。它是讲个方面的问题,讲的是什麽,具体情况如何。这点无论如何强调都不过分。太精辟了, 大约三个星期前读完OG,完成LG扫盲, 我的深刻感受是一定要紧扣题干的中心论点,讨论同一件事的才可能是正确选项.这也基本上是我随后的做题依据.(不好意思, 别的招我都不会:但我不知道它特别适用哪类题,具体到选项分析也是很模糊的在运用. 你这个例子非常好, 又给了我一个如何具体运用的思考范例!其实我今天在重看OG, 对你的这段话特别有感触. 如OG68A drug that is highly effecti

28、ve in treating many types of infection can, at present, be obtained only from the bark of the ibora, a tree that is quite rare in the wild. It takes the bark of 5,000 tree to make one kilogram of the drug, it follows, therefore, that continued production of the drug must inevitably lead to the ibora

29、's extinction.D. The ibora can be propagated from cuttings and grown under cultivation.E. The ibora generally grows in largely inaccessibly places.当时我知道选D, 但我不知道为什么E不对. 现在再看OG的解释, 就是你上面那段话的具体运用了:题干结论:continued production of the drug must inevitably lead to the ibora's extinction.而E 讨论的是还能不能c

30、ontinue的问题.即使它反驳了extinction, 也是因为无法继续生产而使树不会extinction, 而不是反驳结论所表述的持续的生产而使树extinction.其实重要的不是答案,而是为什么对,为什么错,重要在推理的过程.这是我非常喜欢这个小教室的原因.每次都能学到东西.你的这种分析法,对我来说,比feifei逻辑的讲解好太多了:再举一个因果型结论的逆否命题加强例子-摘自XDFThe population of bird F declined between 1950-1960 and reached an all-time low in 1970. This declinatio

31、n was attributed by scientist to the widespread use of DDT in rural areas.Which of the following best support above claim made by the scientist?A. DDT was not generally in use in areas devoted to heavy industry.B. In the time since the use of DDT was banned in 1972, the population of F has been stea

32、dily increasing.C. F, like other birds, abondon eggs in the nests even if the eggs remain intact.D. Other birds that F prey on were not adversefly affected by DDT in the same area.E. Other birds that similiar to F are found in the same area as theF.结论是:F数量下降=科学家认为是DDT的使用所导致的。逆否命题:不使用DDT=F数量不下降或上升。1。

33、携隐说得对,该题是“无因无果”型加强。逆否命题是属于充分必要的范畴,该题是因果关系的范畴,不要混淆。该题没有充分必要关系,因为没有充分必要条件的指示词2。D错的原因是原文在讲Bird F,和Other bird无关。D讲的是Other bird。关于逻辑中数量范围的问题数量的范围是逻辑题常考,特别是MUST BE问题,混淆答案也常来于此。下面一题是LSAT,先讨论,后再公布答案及解释。(V ALARIE说得对,纪念完了,我们要更加努力去学习The importance of the ozone layer to terrestrial animals is that it entirely f

34、ilters out some wavelengths of light but lets others through. Holes in the ozone layer and the dangers associated with these holes are well documented. However, one danger that has not been given sufficient attention is that these holes could lead to severe eye damage for animals of many species.Whi

35、ch one of the following is most strongly supported by the statements above, if they are true.A. All wavelengths of sunlight that can cause eye damage are filtered out by the ozone layer where it is intact.B. Few species of animals live on a part of the earth's surface that is not threatened by h

36、oles in the ozone layerC. Some species of animals have eyes that will not suffer any damage when exposed to unfiltered sunlightD. A single wavelength of sunlight can cause severe damage to the eyes of most species of animalsE. Some wavelengths of sunlight that cause eye damage are more likely to rea

37、ch the earth's surface where there are holes in the ozone layer than where there are not,SORRY,这道题给忘了。大家的答案都对了,是EThe importance of the ozone layer to terrestrial animals is that it entirely filters out some wavelengths of light but lets others through. Holes in the ozone layer and the dangers as

38、sociated with these holes are well documented. However, one danger that has not been given sufficientattention is that these holes could lead to severe eye damage for animals of many species.Which one of the following is most strongly supported by the statements above, if they are true.A. All wavele

39、ngths of sunlight that can cause eye damage are filtered out by the ozone layer where it is intact.错的原因:All wavelengths 太strong。原文只知完好的臭氧层滤掉一部分光,让一部分通过,并说通过的那部分对很多动物有害。从这点很容易误认有害的都给滤掉了。其实原文没说是否那通过的一部分是否含有有害波长。所以错。B. Few species of animals live on a part of the earth's surface that is not threate

40、ned by holes in the ozone layer错的原因:原文只说有HOLE可能会使很多动物受伤害,从这点也许可以推出有动物生活在受HOLE威胁的地方,但原文没说有没有动物生活在不受HOLE威胁的地方,故错。C. Some species of animals have eyes that will not suffer any damage when exposed to unfiltered sunlight错的原因:有些人容易选这个,因为原文最后一句话说HOLE会伤害很多动物的眼睛,就是说很多动物的眼睛会受伤害,既然有很多的眼睛受伤害,就有不受伤害的。错。关键是理解原文最后

41、一句话的many。其实相当于some ,表达的是有的概念,就是可以是1-100。相对或取非的概念为NONE。就是说它们可以包括全部100。所以有可能全部动物眼睛都会受HOLE伤害。即C可能对,也可能不对,不是MUST BE TRUE。故错。D. A single wavelength of sunlight can cause severe damage to the eyes of most species of animals错的原因:也是容易选错,因为原文的最后一句话加上中文对MANY和MOST(都是很多的理解。其实MOST(多数是指51-100。MANY指1-100。所以不能从MANY

42、 推出MOST,从MOST倒可以推出MANY。即原文用MOST,D选项用MANY,则为答案。E. Some wavelengths of sunlight that cause eye damage are more likely to reach the earth's surface where there are holes in the ozone layer than where there are not, 从原文最后两句话可知完好的臭氧层滤掉了部分有害的光线,则说明有洞时,有害的光线更易到达地球。故对。最后强调一点该问题虽然是MOST STRONGL Y SUPPORTE

43、D,但不会出现两个能从原文MUST BE得出的答案,因为该题归为MUST BE TRUE题型,当然不存在支持的程度问题。FLAW IN THE REASONING QUESTIONSThe correct answer will identify the error in the authors reasoning and describe that error in general terms. Closely examine the relationship between the premises and the conclusion1. UNCERTAIN USE OF A TERM

44、OR CONCEPTAmbiguous use/different meaning/in two different ways/equivocate/shift in meaning/fails to define2. SOURCE ARGUMENT(针对人Attacks the person (or source instead of the argument they advance.Makes an attack on the character of opponentsIt is directed against the proponent of a claim rather than

45、 against the claim itselfHe directs his criticism against the person making the argument rather than directing it against the argument itselfIt draws conclusions about the merit of a position and about the content of that position from evidence about the positions sourceAssuming that a claim is fals

46、e on the grounds that the person defending it is of questionable character3. CIRCULAR REASONING(the premise and the conclusion are identical in meaning Assumes as true what is supposed to be proved.It assumes what it seeks to establishArgues circularly by assuming the conclusion is true in stating t

47、he premisesPresupposes the truth of what it sets out to proveThe argument assumes what it is attempting to demonstrateIt takes for granted the very claim that it sets out to establishIt offers, in place of support for its conclusion, a mere restatement of that conclusion4. ERROR OF CONDITIONAL REASO

48、NINGIt is often used the word “sufficient(assured”, “necessary(required” to indicate this kind of errors Taking the nonexistence of sth as evidence that a necessary precondition for that thing also did not exist (MISTAKEN NEGA TIONMistakes being sufficient to justify punishment for being required to

49、 justify it (MISTAKEN REVERSALIt treats sth that is necessary for bringing about a state of affairs as sth that is sufficient to bring about a state of affair(CONFUSES A NECESSARY CONDITION FOR A SUFFICIENT CONDITIONFrom the assertion that sth is necessary to a moral order, the argument concludes th

50、at that thing is sufficient for an element of the moral order to be realized (CONFUSES A NECESSARY CONDITION FOR A SUFFICIENT CONDITIONConfuses a sufficient condition with a required condition (CONFUSE A SUFFICIENT CONDITION FOR A NECESSARY CONDITIONInfers from the idea that the current geography of

51、 modern cities resulted from a particular cause that it could only have resulted from that cause.5. MISTAKEN CAUSE AND EFFECTNote the frequency with which the word “cause ” or ”effect” are used(1 assuming a causal relationship on the basis of the sequence of eventsmistakes a temporal relationship fo

52、r a causal relationship(2 assuming a causal relationship when only a correlation existsconfusing the coincidence of two events with a causal relation between the twoassumes a causal relationship where only a correlation has been indicated(3 failure to consider an alternative cause for the effect, or

53、 an alternative cause for both the cause and the effectfails to exclude an alternative explanation for the observed effectoverlooks the possibility that the same thing may causally contribute both to education and togood health(4 failure to consider that the events may be reversedthe author mistakes

54、 an effect for cause6. STRAW MANThe author attempts to attack an opponents position by ignoring the actual statement made by the opposing speaker and instead distorts and refashions the argument, making it weaker in the process. Often use the phrase “what youre saying is” or ”if I understand you cor

55、rectly” to preface the refashioned and weakened argumentRefutes a distorted version of an opposing positionMisdescribing the stu dent representatives position, thereby making it easier to challenge Portrays opponents views as more extreme than they really areDistorts the proposal advanced by opponen

56、ts7. GENERAL LACK OF RELEVANT EVIDENCE FOR THE CONCLUSIONThe author cites irrelevant dataDraws a conclusion that is broader in scope than is warranted by the evidence advancedIt uses irrelevant facts to justify a claim about the quality of the disputed productIt fails to give any reason for the judg

57、ment it reachesIt introduces information unrelated to its conclusion as evidence in support of that conclusion8. INTERNAL CONTRADICTIONBases a conclusion on claims that are inconsistent with each otherThe author makes incompatible assumptionsIntroduce information that actually contradicts the conclu

58、sionOffers in support of its conclusion pieces of evidence that are mutually contradictorySome of the evidence presented in support of the conclusion is inconsistent with other evidence providedAssumes sth that it later denies, resulting a contradiction9. APPEAL FALLACIES(1 appeal to authoritythe judgment of experts is applied to a matter in which their expertise is irrelevantthe argument inappropriately appeals to the authority of the majorit relies on the judgment of experts in a matter to which their expertise is irrelevant