相信很多同学都听过PowerScore这本书，但是可能对这本书还不是很了解，今天小编就摘录了此书中的一些逻辑要点，大家可以通过参考这些要点决定是否要运用此书。
Chapter 1 GMAT exam overview
A strong beginning is needed!
A strong beginning followed by a weak finish will produce a higher score than a weak beginning followed by a strong finish. It is essential that your performance early in the section be as strong as possible, even if this requires using more than the average time allotted per question. 开始做的慢一点，没关系，保证正确。
Chapter 2&3 the basics of Critical Reasoning/question stem and answer choices
l Primary Objective #1: Determine whether the stimulus contains an argument or if it is only a set of factual statements. 辨认是议论文，还是简单陈述事实。
l Primary Objective #2: If the stimulus contains an argument, identify the conclusion of the argument. If the stimulus contains a fact set, examine each fact. 找出议论文的结论，检验每条事实。
1. 区分: premise 和 conclusion
a) Premise:
because, since, for, for example, for the reason that, in that, given that, as indicated by, due to, owing to, this can be seen from, we know this by
b) Conclusion:
Thus, therefore, hence, consequently, as a result, so, accordingly, clearly, must be that, shows that, conclude that, follows that, for this reason
c) Additional premise:
Furthermore, moreover, besides, in addition, what’s more
d) Counter-premise Indicators:
But, yet, however, on the other hand, admittedly, in contrast, although, even though, still, whereas, in spite of, despite, after all
2. Complex arguments
Premise → Conclusion/premise → Conclusion 这类情况常出 Bold Reasoing 类问题。
3. A commonly used construction一个常用的反驳已有观点的结构
The construction is to raise a viewpoint at the beginning of the stimulus and then disagree with it immediately thereafter.
Construction:
A number (some, many, etc.) of people (critics, students, teachers, legislators, vegetarians, psychologists etc.) believe (claim, propose, argue, etc.) that…
4. Truth versus Validity
GMAT 关于论据是否得出结论而不是论据本身是否正确。
l Primary Objective #3: If the stimulus contains an argument, determine whether the argument is strong or weak. 检验论证是否够强，也就是premise 足够论证 conclusion与否。
1. Inference and Assumption
Inference = MUST BE TRUE 是由文章得来的。
Assumption 是文章默认的。
l Primary Objective #4: Read closely and know precisely what the author said. Do not generalize!注意作者论述的范围，不可一概而论，也不可排除特例。错误选项常常超出论述范围。
l Primary Objective #5: Carefully read and identify the question stem. Do not assume that certain words are automatically associated with certain question types.仔细分析题干，确定题目类型。
1. 题目共分为四大类family，一共有十种。
a) Family One: Prove (accept the stimulus informaton)
i. Must be true (Fact set)
ii. Main point
iii. Method of reasoning
iv. Flaw in the reasoning
v. Parallel reasoning
b) Family Two: Help (accept choice information)
i. Assumption
ii. Strengthen/ Support
iii. Resolve the Paradox (Fact set)
c) Family Three: Hurt (accept choice information)
i. Weaken
d) Other type
i. Evaluation
2. “Except” and “Least” in question stem, 记住 not weaken ≠ strengthen
l Primary Objective #6: Prephrase: after reading the question stem, take a moment to mentally formulate your answer to the question stem. 自己尝试想出答案，通过大量做题可以有帮助。
l Primary Objective #7: Always read each of the five answer choices. 每个选项都要读，排除法。
l Primary Objective #8: Separate the answer choices into Contenders and Losers. After completing this process, review the contenders and decide which answer is the correct one. 做题过程中，用手指排除掉Loser，保留Contender，最后得出最优，不要犹豫于一个contender，也不要重复看Loser.
l Primary Objective #9: If all five answer choices appear to be Losers, return to the stimulus and re-evaluate the argument. 如果那个都不像对的，再好好看看。
Chapter 4 Must Be True Questions
l The correct answer to a Must Be True question can always be proven by referring to the facts stated in the stimulus.
l Do not bring in information from outside the stimulus
l It is hard to prephrase an answer to a Must Be True question.
l Do not select an answer that “sounds good”, which is a “common sense” option, but not based on the stimulus.
l Correct answers in Must Be True questions:
1. Paraphrased answers: answers that restate a portion of the stimulus in different terms.
2. Combination answers: answers that are the sum of two or more stimulus statements
l Incorrect answers in Must Be True questions:
1. Could be true or likely to be true
2. Exaggerated answers: some→most, “likely” being dropped
3. “New” information answers: information not mentioned explicitly in the stimulus
4. The Shell Game
5. The opposite answer
6. The reverse answer: Ex. Many people have some types→Some people have many types
l 区分 Stimulus opinions/ Assertions
1. Opinions： 文中的人的观点,并不一定是事实
a) Scientists believe that..
b) I think…
2. Assertions : factual statements
a) It is…
b) There are…
c) It has been proven..
d) Scientists found…
e) In 1890…
3. If stimulus contains “Assertions”, then answers present “Opinions” must be incorrect. Similarly, if stimulus contains “Opinions”, then answers present “Assertions” must be incorrect.
l Sufficient (充分条件) and Necessary (必要条件) conditions
Example： A+ (Sufficient) → Study (Necessary)
1. Sufficient condition Indicators:
If, when, whenever, every, all, any, people who, in order to
2. Necessary Condition Indicators:
Then, only, only if, must, required, unless, except, until, without
Chapter 5 Main Point Questions
l Find the conclusion of the passage
l Two incorrect answer types:
1. True but now encapsulate the author’s point
2. Simply repeat the premises of the argument
Chapter 6 Weaken questions
l Focus on the conclusion, then prephrase if you can.
l “Weaken” indicators: weaken, attack, undermine, refute, argue against, call into question, cast doubt, challenge, damage, counter…
l How to weaken an argument (here weaken ≠ destroy)
1. The premises: to attack the premises on which the conclusion rests. 这个基本见不着
2. The conclusion: to attack the argument’s conclusion will attack assumptions made by the author.
a) The stimulus for weaken questions contain errors of assumption
b) The author will fail to consider other possibilities or leave out a key piece of information
c) Always look for the one that attacks the way the author arrived at the conclusion.
l Common weakening scenarios
1. Incomplete information
2. Improper comparison
3. Qualified (有限制的) conclusion
l Three incorrect answer traps
1. Opposite answers
2. Shell game answers
3. Out of scope answer
Chapter 7 Cause and Effect reasoning 因果题型
l Cause makes the effects happen, some indicators:
Caused by, because of, responsible for, reason for, leads to, induced by, promoted by, determined by, produced by, product of, played a role in, was a factor in, is an effect of
l Causality in the Conclusion VS Causality in the Premises 做原因
1. Conclusion 作 casual，the reasoning is flawed.
Example: flawed reasoning
Premise: In North America, people drink a lot of milk
Premise: There is a high frequency of cancer in North America
Conclusion: Therefore, drinking milk causes cancer.
2. Premises作 casual，the reasoning may be flawed, maybe not.
Example: valid reasoning
Premise: Drinking milk causes cancer.
Premise: In North America, people drink a lot of milk.
Conclusion: Therefore, there is a high frequency of cancer among residents in North America
l Situations that leads to Error of Causality
1. One event occurs before another 前后发生
2. Two (or more) events occur at the same time 同时发生
l Central assumption of causal conclusions: The cause is the ONLY cause to the effect, and that cause will ALWAYS produce the effect.
l How to attack a causal conclusion
1. Find an alternative cause of the stated effect另辟蹊径
2. Show that even when the cause occurs, the effect does not occur 因没有导致果
3. Show that although the effect occurs, the cause did not occur 果发生，因没有发生
4. Show that the stated relationship is reversed 说明因果倒置了
5. Show that a statistical problem exists with the data used to make the causal statement 说明数据有问题，或者没有代表性
Chapter 8 Strengthen and Assumption questions
l The more you know about the specifics of the conclusion, the better armed you will be to differentiate between correct and incorrect answers.
l An assumption is simply an unstated premise.
l Strengthen question stem: “which of the following, if true, most strengthen / supports / helps / justifies…..”
l How to strengthen an argument:
1. Identify the conclusion – this is what you are trying to strengthen!
2. Personalize the argument.
3. Look for weaknesses in the argument. Find the “missing link” between conclusion and premises, which is the assumption that validates part of the author’s thinking.
4. Answers that strengthen the analogy or survey, or establish their soundness, are usually correct.
5. Remember the correct answer can strengthen the argument just a little or a lot.
l Incorrect answer
1. Opposite answers.
2. Shell game answers.
3. Out of scope answers.
l Causality and strengthen questions, how to support a cause and effect relationship:
1. Eliminate any alternative causes for the stated effect 排除其他可能
2. Show that when the cause occurs, the effects occurs 陈明因果发生关系
3. Show that when the cause does not occur, the effect does not occur 因未发生，果未发
4. Eliminate the possibility that the stated relationship is reversed 排除因果倒置可能
5. Show that the data used to make the causal statement are accurate, or eliminate possible problems with the data 陈明数据可靠性
l Assumption Questions basic
1. Assumption answer choices cannot contain extraneous information.
2. Assumption answers contain statements that were used to make the conclusion.
l Supporter/ Defender Assumption model
1. Supporter role is the traditional linking role, linking together new or rogue elements in the stimulus or fill logical gaps in the argument.
2. Defender role is the assumption protects the argument by eliminating ideas that could weaken the argument.
l The assumption negation technique 通过把选项转换为否定句子，如果变成weaken，就说明是correct选项
1. Logically negate the answer choices under consideration
a) Logically negate ≠ polar opposite
Example: “I went to the beach every day last week.”
Logical opposite: “I did not go to the beach every day last week.”
Polar opposite: “I did not go to the beach any day last week.”
2. The negated answer choice that attacks the argument will be the correct answer
l Three quirks of assumption question answer choices
1. Watch for answers starting with the phrase “at least one” or “at least some.”有可能对
2. Avoid answers that claim an idea was the most important consideration for the author. Such as “the primary purpose”, “the top priority”, or “the main factor.”
3. Watch for the use of “not” or negatives in assumption answer choices. 有可能做defender对。
l Fill in the Blank questions
1. Assumption question
a) ….because____
b) ….is the fact that_____
c) ….is that____
d) ….since____
1. Main point question (extremely rare)
Chapter 9 Resolve the Paradox questions
l Contradiction words:
But, however, yet, although, paradoxically, surprisingly
l Question stem indicates:
Action: resolve, explain, reconcile
Problem: paradox, discrepancy, contradiction, conflict, puzzle
l Active resolution: 寻找使得 coexist 而不是 destroy 一方。
l Address the facts: 不要被不合乎题干的情形给出的答案所迷惑。
Chapter 10 Methods of reasoning and flaw in the reasoning question
l Methods of reasoning questions are simply abstract Must Be True question, the logical organization of the argument.
l Incorrect answers in method and flaw questions
1. “New” Element Answers
2. Half Right, Half wrong answers
3. Exaggerated answers
4. The opposite answer
5. The reverse answer
l Common errors of reasoning explained
1. Uncertain use of a term or concept 偷换概念
2. Source argument 对人不对事
3. Critical reasoning 循环推理
4. Mistaken cause and effect 错判因果
a) Assuming a causal relationship on the basis of the consequence of events. 前后
b) Assuming a causal relationship when only a correlation exists.一同发生
c) Failure to consider an alternative cause for the effect.没有考虑其他可能
d) Failure to consider that the events may be reversed.因果倒置
5. Straw Man 假想敌，曲解对方
6. General lack of relevant evidence for the conclusion 无效论证
7. Internal contradiction 自相矛盾
8. Appeal fallacies 脑残粉
a) Appeal to authority 迎合权威
b) Appeal to popular opinion/ appeal to numbers 迎合流行
c) Appeal to emotion 迎合感情用事
9. Survey errors 调查错误
a) The survey uses a biased sample 没有代表性的样本
b) The survey questions are improperly constructed 问题设计失误
c) Respondents to the survey give inaccurate response 受访对象回答不准确
10. Exceptional case/ overgeneralization 特例/ 过度概括
11. Errors of composition and division 以偏概全
12. False analogy 错误类比
13. False dilemma 两难困境
14. Errors in the use of evidence 使用证据的错误
a) Lack of evidence for a position is taken to prove that position is false 缺少attack证据
b) Lack of evidence against a position is taken to prove that position is true 缺少agree证据
c) Some evidence against a position is taken to prove that position is false 证据只可以weaken不能充分否定
d) Some evidence for a position is taken to prove that position is true 证据只能support不能充分证实
15. Time shift errors: assuming the conditions will remain constant over time 风水轮流转
l Method of reasoning – Bold argument part question. 两部分加黑句子的作用，排除法
Chapter 11 Parallel reasoning questions
l 难度较大，出现说明是好消息
l Elements do not need to be paralleled:
1. Topic of the stimulus
2. The order of presentation of the premises and conclusion in the stimulus
l The order of matching:
1. Match the method of reasoning
2. Match the conclusion
3. Match the premises
4. Match the validity of the argument
Chapter 12 Numbers and percentages
l 注意percentage 和 number 没有绝对的关系，小心陷阱将之等同，数学感觉好的绕道走。
Chapter 13 Evaluate the argument and cannot be true questions
l The information that would best help determine the logical validity of the argument presented in the stimulus. You must select the answer choice that decides whether the argument is good or bad.
l The variance test: 将选项赋予 Yes 和 no 的值，如果是正确选项，one response should strengthen the argument and one response should weaken the argument.
l CANNOT be true question， 是 Must be true 的变形， 略过。
l Principle question, 略过。
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