GMAT邏輯講義

1、GMAT邏輯講義 一、 歸納題：從上到下（從原文到答案） 讀題 1） 注意條件句，如if, as long as等，例 第二冊P203 (20) 2） 注意有沒有否絕對化詞，如only，any，no, solely等 3） 注意有沒有數(shù)學上的等式、不等式關系或比例(percent, proportion) 等， 例第二冊第二冊P117 、 P126、 P169(1)、P248(14) 判斷答案的原則：(1) 答案中不能出現(xiàn)原文中沒有的新概念（包括新的動詞、形容詞 、 名詞等，但是需要同義詞的出現(xiàn)） (2) 若原文在某一信息點上沒有絕對化概念，那么答案中也沒 有 (3) 不能出現(xiàn)新的比較 (4)

2、 答案不能和原文信息相違背。 例題：第二冊P115 P116 P123 P126 推導結構 例題 第二冊P122 ， 講義section 1(19題) 2）理解命題及常用表達（這一知識點需要好好把握，不僅僅在歸納題中有用， 在邏輯 描述題中，邏輯結構一致性，對上文最好的批評等問法中 都出現(xiàn)） 原命題和逆否命題為等價命題，逆命題和否命題為等價命題 (AB+C, 逆否命題為B/CA), (A+BC, 則其逆否命題為C AB) II. unless :=if not 即 not A unless B表達為 AB A unless B表達為非AB only if: A only if B表達為AB i

3、f only: A if only B表達為BA A is necessary to B: BA Whenever, whoever, wherever :=if 二、Weaken 和Support演繹題型（從下到上，即從答案到原文） weaken support Reasoning Premise（前提），Conclusion（結論），Reasoning(推理過程，前提到結論的思維 變遷) 演繹題所面臨的是一個“待評價的推理”，也就是從前提到結論的這個推理是否能夠 成立我是不知道的，我需要對它進行評價。根據(jù)問題的不同問法，確定不同的解題態(tài)度 ，問支持，就找一個選項說它可能對，問反對，找一個選

4、項說它不一定對，問假設考慮 使結論成立需要什么，哪一個是使其成立的一個必要條件。 1如何正確理解weaken , support 支持：(support),將答案放在論據(jù)和結論之間，對原文推理或者結論有支持作用就可 以， 所以既可非充分又可非必要 駁斥：（weaken），將答案放在論據(jù)和結論之間，對原文推理或者結論有駁斥作用就 可以， 所以也是既可非充分又可非必要 如何理解充分和必要 1充分：所謂充分條件就是僅有這條件就足以帶來結果，不需考慮別的條件了。 它是誰成立，誰一定也成立，比如AB, 如果A成立，那么一定有B 2必要：所謂必要條件就是沒有這個條件結果一定不對。 2前因后果結構 推理中的

5、前提和結論在大多數(shù)情況下用因果關系來表示，根據(jù)因果關系中的結果成立 不成立我們分為兩種邏輯結構，前因后果結果和Causal Explanations結構，以后講的答 案方向點區(qū)別并不大，但是我們?yōu)榱死诶斫膺M行這個分類 前因后果結構表示： (AB) 從這個原因是否能夠得到這個結果？(注意because, since, for等原因引導詞 ) 這個方法是否能夠達到這個目的？(注意by引導方法，To的不定式引導目的) 從這個條件是否能夠得到這個結論？(注意if，when, as long as等引導條件 ) 注意上面的結果、結論到底能不能夠成立，目的到底能不能夠達到，還不確定 。 駁斥、支持方向：

6、 A方法可行， P122(7) A-B之間 P113(3)、P116(12) A之外因素的影響B(tài) P113(2)、P123(11) 直接對B說 講義Section 1第4題 3Causal Explanations a. 對一個事實的發(fā)生、一個現(xiàn)象的存在，一個研究的發(fā)現(xiàn)，提出一種解釋 也就是為什么這個事實會發(fā)生呢?為什么這個現(xiàn)象會存在呢?是這個原因?qū)е碌?b. 從一個已知的,已經(jīng)發(fā)生的事實,已經(jīng)存在的現(xiàn)象中得到一個結論,這個結論其實還是 對上面的事實發(fā)生、現(xiàn)象存在做出了一種解釋 注意上面的結果、事實，現(xiàn)象都是已經(jīng)發(fā)生，已經(jīng)成立了，問到底是不是這個原因?qū)?致的， 這也是Causal Explan

7、ation結構和前因后果結構最本質(zhì)的區(qū)別，務必仔細體會。 Causal Explanation結構的典型引導詞：result、 due to、reason 、attribute to、 hypothesize、 the explanation is 、be responsible for 、 把這個事實當作B, 把這個原因解釋當作A， 答案方向： 這個原因和結果之間的關系？（B-A之間） 有沒有別的原因來對上面的事實、現(xiàn)象、研究發(fā)現(xiàn)作出解釋（A之外的其他 原因） 支持：直接： 就是這原因?qū)е陆Y果，具體還可以表現(xiàn)為沒有這個原因就沒有這個結果。 例題：講義Section 1第1題， P201(12

8、) 間接：沒有別的原因解釋上面的事實或現(xiàn)象 駁斥：直接：原因和結果無關，具體表現(xiàn)為有這個原因沒有這個結果或者沒有這個原因 有這個結果 例題：P114(7), P115(9) 間接：還有別的原因存在解釋上面的事實或現(xiàn)象 P124(13) 如何統(tǒng)一兩種結構的答案方向？ 4Weaken, Support讀題： 1）重點是找出原因和結果兩句話，如果沒有任何原因指示詞，那么重點在 結論，緊 靠結論因果詞（therefore ,thus）前面的往往就是原因 2）對to的不定式要讀出(往往表示為對一個目的提出一個方法) 3）對any, all, none, everyone, each, no, in ge

9、neral, on the whole 等 詞需注意，因可能會為范圍差異 4）對only, solely加以注意，例：第四冊：P18 5）對動詞的程度修飾，例：第四冊：P7 5. 一些輔助的類型 范圍差異、數(shù)據(jù)得結果、因果順序、比較原則 三：“Assumption”題型 假設定義：使結論成立的必要條件 讀題： 和weaken ,support讀題方法完全一樣，再注意when、if等詞語 答案方向： 前因后果結構 1)因果關系差異概念的橋梁作用 (A-B之間) 例題：P115(8)、P122(5)、P200(7)、P202(15)、P248(12)、P249(16 ) 2)A可行性或者原因有意義

10、：P228(9)、P246(7) 3)沒有其他的因素來影響這個結果或者結論 P248(12)、P250(18) Causal Explanations: 1)沒有這個原因就沒有這個結果 （兩者之間） 3)沒有其他的原因來解釋上面的事實或者現(xiàn)象 P173(16)、P229(13) 注意此類假設其答案中，很可能會有否定詞或類似否定概念出現(xiàn) 注意： 和weaken、support一樣，這兩種結構的答案方向完全可以統(tǒng)一 四：“evaluate”題型 1定義： 對某個問題兩方面的回答（yes and no）或者某個信息兩方面的回答，對原 文推理如果 一方面回答起到支持作用，則另一方面回答起到駁斥作用，如

11、果一方面回答起到 駁斥作 用，則另一方面回答起到支持作用，這個問題或者信息就對原文有評價作用。 注意一定是yes and no回答都起到作用，如果僅僅一方面回答起到作用，則 不是評價 2.答案方向： 1）直接說，結果和原因之間有沒有關系(A-B) 例：第二冊P172(10)、 P198(3) 2）A是否可行或者有意義。 講義section 1(11題) 3）間接性答案：除A之外是否還有別的因素影響B(tài)， 例：第四冊P104 或者有沒有其他的原因來解釋原文中存在的事實或者現(xiàn)象 注意：evaluation、 assumption和weaken, support的統(tǒng)一 五：解釋現(xiàn)象 1解釋result

12、, situation等，統(tǒng)稱為解釋結果 具體讀出要解釋什么，現(xiàn)象是什么，解題要點：抓住要解釋的對象，具體發(fā)生了什么 變化 2解釋矛盾，找一個選項說明為什么會存在這種矛盾，解題主要抓住區(qū)別點 3答案要明確，滿足無推導、無充分性。講義section 1(第20題) 六完成一段話“題型” 找答案需滿足：1）在句子意思上滿足原文，特別是可將最后一句話補全 2）答案必須和原文前半段描述有關系 例：第二冊：P60 P70 P201 七“上文使用何種有疑問技術”題型（邏輯描述） 并不是讓你找一個選項對上文推理進行駁斥，也不是問原文推理的缺陷，而是讓你用邏 輯描述的語言來描述一下原文的推導過程。 例：第三冊

13、P4 （17）第四冊P85 八、提高（由學生自己去訓練培養(yǎng)對weaken support等題的感覺） 1Weaken:求異 2Support:求同 所謂求同、求異就是答案和原文的一致或不一致，而不是答案中誰與誰一致或不一致， 它要求既不要考慮原文的因果之間為什么會如此，也不要考慮答案中因果之間為什么會 如此，更不可考慮此答案是如何使得對原文有支持或駁斥作用的，而僅僅辨認在答案滿 足和原文有關時是保持和原文一致還是不一致，這一點往往對于難題來講，特別還僅僅 剩下兩個選項需要辨別的時候，更為有用 例：“因為這兒有個人，所以螞蟻有兩條腿?！睂@一論證的支持或駁斥不應考慮為什 么人和螞蟻有關，而只考慮

14、在答案中說有人或說螞蟻兩條腿的情況下，找其相同或不同 就可以了，如“相鄰近處沒有人，螞蟻也有兩條腿”，在滿足說螞蟻有兩條腿時說的是 沒有人，和上邊論述不一致，因此可weaken同理說“在鄰近處沒有人，螞蟻也就無兩條 腿，”就有support作用，你所需做的僅僅是尋找相同或不同點，僅此而已，大家可由第 三冊上P1 P2 P3 P5 P28 P29 P46 P47 等題 去理解weaken，由第二冊上P30 P31 P45 P48 等理解support. 九、最后讀題 GMAT改為機考后，邏輯題長度明顯增加，對此除提高閱讀能力外（不是閱讀技巧） ，主要要做訓練看對一段話中在僅讀一遍的情況下，究竟哪

15、句話為結論，然后看出和結 論相關的直接原因是什么，最后次要地看出和直接原因相關的性質(zhì)點中，原文提出過什 么就可以了，但對于“歸納”題型只能學會一邊讀一邊思考原文的層次是什么，腦中將 層次留下，無其他好方法。 Section 1 1. The town of Stavanger, Norway, was quiet and peaceful until the early 1960s, when Stavanger became Norways center for offshore oil exploration. Between then and now, violent crime and

16、 vandalism in Stavanger have greatly increased. Clearly, these social problems are among the results of Stavangers oil boom. Which of the following, if it occurred between the early 1960s and now, gives the strongest support to the argument above? (A) The people of Stavanger rarely regret that their

17、 town was chosen to be Norways center for offshore oil exploration (B) Norwegian sociologists expressed grave concern about the increase in violent crime and vandalism in Stavanger. (C) Violent crime and vandalism have remained low in Norwegian towns that had no oil boom. (D) Nonviolent crime, drug

18、addiction, and divorce in Stavanger increased approximately as much as violent crime and vandalism did. (E) The oil boom necessitated the building of wider roads for the increased traffic in Stavanger. 2. Since 1945 there have been numerous international confrontations as tense as those that precipi

19、tated the Second World War, and yet no large-scale conflict has resulted. To explain this, some argue that fear of enormous destruction such as the Second World War produced has had a dramatic deterrent effect. Which of the following, if true, most seriously weakens the deterrent theory mentioned ab

20、ove? (A) After the First World War, the fear of great future destruction was as intense as it was after the Second World war. (B) Psychologists have determined that the fear of retaliation tends to temper aggressiveness among human beings. (C) The Second World War was far less destructive than most

21、people generally believe. (D) Fear of repeating the levels of destruction that the Second World War produced is as pervasive today as it was forty years ago. (E) Many of the international confrontations that have occurred since 1945 have involved countries that participated in the Second World War.

22、3. A list of the fifteen operas most frequently performed in recent times includes no works by the nineteenth century German composer Richard Wagner. Although music producers tend to produce what audiences want, relative infrequency of performance probably does not indicate lack of popularity in Wag

23、ners case, since Wagners operas are notoriously expensive to perform on stage. Which of the following, if true, most strongly support the conclusion of the argument above？ (A)The list of most frequently performed operas does not include operas produced by small amateur groups. (B)Some opera companie

24、s are backed by patrons who are willing to commit large sums of money in order to enjoy lavish productions. (C)All of the fifteen most frequently performed operas of recent times are works that have been popular for at least 75 years. (D)More recordings have been produced recently of the works of Wa

25、gner than of the works of any other composer of opera. (E)Operatic works of all kinds have been increasing in popularity in recent years. 4. V-shaped walled structures in central Asia were used by prehistoric hunters who drove hoofed animals into an enclosure at the point of the V. The central Asian

26、s who built these structures probably learned this hunting technique from invaders from southwest Asia, because the arrival of invaders from a region in southwest Asia where similar structures had long been used coincides roughly with the building of the earliest of such structures in central Asia.

27、Which of the following, if true, most strengthens the argument? (A) Excavations in the central Asian region do not indicate whether invaders from southwest Asia settled permanently in central Asia. (B) The V-shaped structures in central Asia were roughly 70 meters long, whereas the similar structure

28、s in southwest Asia were usually over 300 meters long. (C) The walls of the structures in central Asia were made from earth, whereas the walls of the structures in southwest Asia were made of rock. (D) The earliest examples of V-shaped walled structures in central Asia were of an advanced design. (E

29、) Some of the walled structures used for hunting in southwest Asia were built well after the earliest such structures were built in central Asia. 5. The average age and racing experience of the drivers at the Indianapolis 500 automobile race increased each year between 1965 and 1980. The reason for

30、the increase is that high-speed racing drivers were living longer than their predecessors. Race-car safety features that reduced the severity of crashes of the kind that formerly took drivers lives were primarily responsible for the increase in the average age of the Indianapolis 500 competitors. Wh

31、ich of the following, if true, would be most likely to be part of the evidence used to show that safety features on the cars that protected drivers in major crashes were responsible for the increase in the average age of drivers at the Indianapolis race? (A) Younger drivers at high-speed racetracks

32、were involved in major accidents at a slightly higher rate than were older drivers between 1965 and 1980. (B) Major accidents on high-speed racetracks occurred at about the same frequency in the years after 1965 as in the years before 1965. (C) The average age of drivers attempting to qualify for th

33、e Indianapolis 500 decreased slightly between 1965 and 1980. (D) Accidents on highways in the United States occurred at about the same frequency in the years after 1965 as in the years before 1965. (E) Other safety features, involving the condition of the racetrack and the uniforms worn by the drive

34、rs while driving, were adopted at Indianapolis between 1965 and 1980. 6. Calvin: Fire insurance policies are disadvanta- geous to policyholders. The typical poli- cyholder always pays more in premiums than he or she collects in payments on policies. Lorraine: Yes, but policyholders are still right i

35、n thinking that it is to their advantage to hold an insurance policy. The peace of mind that comes from having an insurance policy is the main advantage to the poli- cyholder. Lorraine addresses Calvins argument by (A) Questioning the source of Calvins factual infor- mation (B) introducing a conside

36、ration neglected by Calvins argument (C) showing that Calvins argument assumes what it sets out to prove (D) challenging the truth of the evidence advanced in Calvins argument (E) showing the irrelevance of Calvins evidence to the conclusion he draws 7.X: When a rare but serious industrial accident

37、occurs, people respond by believing that such accidents are becoming more frequent. This belief is irrational. After all, being dealt four aces in a hand of poker, a rare event, hardly increases ones chances of being dealt four aces in a future hand. Y: To the contrary, the belief is rational becaus

38、e it results in peoples sensing a danger to them- selves not previously sensed and taking precau- tionary actions to prevent similar accidents in the future. Ys attempt to counter Xs claim is best described by which of the following? (A) It questions the aptness of the analogy drawn by X. (B) It mak

39、es apparent Xs failure to consider how people vary in their responses to a serious accident. (C) It shifts the basis for judging rationality to considerations of utility. (D) It offers an alternative explanation of why people form incorrect beliefs. (E) It challenges Xs assumption that the occur- re

40、nce of a single event is sufficient to change a belief. 8. John: It is permissible and even advisable to execute criminals convicted of brutal murders. After all, a publicized execution can serve to deter heinous crimes and thus minimize suffering in the long run. Capital. punishment is a kind of so

41、cietal self-defense. Mary: You are ignoring the prior issue of whether a state or society has the right to take anyones life. If there is no such right. then, the issue of whether capital punishment deters crime is irrelevant. If it were determined dial capital punishment does not serve to deter cri

42、me. Johns and Marys posi- tions would be affected in which of the following ways? (A) Neither Johns nor Marys position would be affected. (B) Both Johns and Marys positions would be weakened. (C) Marys position would be strengthened but Johns position would not be affected. (D) Johns position would

43、be weakened but Marys position would not be affected, (E) Johns position would be weakened and Marys position would be strengthened. 9. Excluding purchases by businesses, the average amount spent on a factory-new car has risen 30 per- cent in the last five years. In the average household budget, the

44、 proportion spent on car purchases has remained unchanged in that period. Therefore the average household budget must have increased by 30 percent over the last five years. Which of the following is an assumption on which the argument relies？ (A)The average number of factory-new cars pur- chased per

45、 household has remained unchanged over the last five years. (B)The average amount spent per car by businesses buying factory-new cars has risen 30 percent in the last five years. (C)The proportion of the average household budget spent on all car-related expenses has remained unchanged over the last

46、five years. (D)The proportion of the average household budget spent on food and housing has remained unchanged over the last five years. (E)The total amount spent nationwide on factory- new cars has increased by 30 percent over the last five years. 10. Editorial： Critics of nuclear power complain ab

47、out the allegedly serious harm that might result from continued operation of existing nuclear power plants. But such concerns do not justify closing these plants；after all, their operation has caused no more harm than that caused by pollution generated by coal-and oil-burning power plants, the most

48、important other sources of energy. Which of the following is an assumption on which the argument depends？ (A) Existing nuclear power plants should be closed only if it can be conclusively demonstrated that their continued operation is likely to cause harm more serious than the harm their operation h

49、as already caused. (B) Closing existing nuclear power plants would require greatly increased reliance on coal-and oil-burning power plants. (C) The harm that has resulted from operation of existing coal and oil-burning power plants has been significant. (D) The harm that a nuclear power plant is lik

50、ely to cause as it continues to operate can be reliably predicted from the past history of nuclear power plants. (E) The only harm that has resulted from operation of existing coal and oil-burning power plants has resulted from the pollution generated by these plants. (F) Closing existing nuclear po

51、wer plants would require increased reliance on coal-and oil-burning power plants. 11. Sleep deprivation is a known cause of workplace error, and many physicians frequently go without sleep for periods of 24 hours or more. However, few of these physicians have, in the course of a routine examination

52、by a peer, been diagnosed with sleep deprivation. So there is little cause for concern that habitual sleep deprivation will cause widespread physician error. The answer to which of the following questions would be most helpful in evaluating the argument？ (A)Do physicians who have been diagnosed with

53、 sleep disorders also show signs of other ills not related to sleep deprivation？ (B)Is the ability to recognize the symptoms of sleep deprivation in others significantly impaired by habitual sleep deprivation？ (C)Do factors other than habitual sleep deprivation ever lead to errors in the workplace on the part of physicians？ (D)Of people who have recently been treated by physicians, what percentage believe that many physicians have occasionally suffered from sleep deprivati