往常逻辑题中考察因果关系的题型很多，不仅在削弱题和支持题中最为常见，也是在其它题型中出现的常客。下面就随小编一起来看一下吧。
Chapter 7 Cause and Effect Reasoning
**Cause and Effect
若结论中出现 XX导致了XX，即结论中出现因果关系，则结论一定有因果错误!但如果XX导致了XX出现在前提中，则结论可能是错的。假如有错误，则原因必不来自前提的因果关系。(即不要怀疑前提的真实性!)
1. Most causal conclusions are flawed because there can be alternative explanations for the stated relationship:
①Another cause could account for the effect
②A third event could have caused both the stated cause and effect
③The situation may in fact be reversed
④The events may be related but not causally
⑤Entire occurrence could be the result of change
2. Causality in the Conclusion versus Causality in the Premises
Casual statements can be found in the premises or conclusion of an argument. If the causal statement is the conclusion, then the reasoning is flawed. If the causal statement is the premise, then the argument may be flawed, but not because of the causal statement.
This is an argument with a causal conclusion:
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
If a causal claim is made in the premises, however, then no causal reasoning error exists in the argument. (Of course, the argument may be flawed in other ways.) As mentioned previously, the makers of the GMAT tend to allow premises to go unchallenged and it is considered acceptable for an author to begin his argument by stating a causal relationship and then continuing from there:
Premise: Drinking milk causes cancer
Premise: The residents of North America drink a lot of milk
Conclusion: Therefore, in North America there is a high frequency of cancer among the residents
3. Situations that can lead to errors of causality
①One event occurs before another
一个事情发生早于另一个
②Two (or more) events occur at the same time
两个事情同时发生
论述到一个事情的发生导致了另一个事情时， GMAT总是认为，这个起因是唯一的起因，结果是唯一的结果
两个事件同时发生，尽管一个可能会引起另一个，但是这两个事件还有可能都是第三个事件的结果，或者他们可以被联系起来不用一个因果关系
4. How to attack a Causal Conclusion
①Find an alternate cause for the stated effect找出另外一个起因 是这个陈述的结果
Because the author believes that there is only one cause, identifying another cause weakens the conclusion.
②Show that even when the cause occurs, the effect does not occur。表明即使 原因发生，结果也不会发生
This type of answer often appears in the form of counterexample. Because the author believes that the cause always produces the effect, any scenario where the cause occurs and the effect does not weakens the conclusion.
小明生病导致不及格
小红也生病了但及格了
③Show that although the effect occurs, the cause did not occur表明虽然结果发生，但是原因没有发生 有果无因
This type of answer often appears in the form of counterexample. Because the author believes that the effect is always produced by the same cause, any scenario where the effect occurs and the cause does not weakens the argument.
小明生病导致了不及格
小红没生病也不及格 其实跟引入他因是一样的 ，说明不是生病导致不及格
④Show that the stated relationship is reversed， 表明因果倒置
Because the author believes that the cause and effect relationship is correctly stated, showing that the relationship is backwards undermines the conclusion.
⑤Show that a statistical problem exists with the data used to make the causal statement.
表明显示因果关关系的 资料不准确
补充: Conditional Reasoning
(Conditional Reasoning在LSAT Logical Reasoning中提及，但没有在GMAT Critical Reasoning中被提及)
Conditional Reasoning Review
A sufficient condition can be defined as an event or circumstance whose occurrence indicates that a necessary condition must also occur.
A necessary condition can be defined as an event or circumstance whose occurrence is required in order for a sufficient condition to occur.
To introduce a sufficient condition: To introduce a necessary condition:
If Then
When Only
Whenever Only if
Every Must
All Required
Any Unless
People who Except
In order to Until
Without
Weakening Conditional Reasoning
As proven by the discussion of the previous problem, there is a simple rule for weakening a conditional conclusion:
To weaken a conditional conclusion, attack the necessary condition by showing that the necessary condition does not need to occur in order for the sufficient condition to occur.
This can be achieved by presenting a counterexample or by presenting information that shows that the sufficient condition can occur without the necessary condition.
This leads to another Classic Combination:
When you have conditional reasoning in the stimulus and a Weaken question, immediately look for an answer that attacks the necessary condition.
引申:
Lawyer的条件型结论：结论带条件(即为充分必要)。WEAKEN的方法显示充分条件成立，必要条件可以不成立。或举反例，或提供有关信息。
解释：
就是要为充分条件找到成立的另一理由，即使没有必要条件，充分条件也可以成立。但是不要倒置了。很多迷惑项是weaken充分条件。题目要weaken的是BàA，如果我们weaken了AàB ，那完全不起作用。
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