MECE ，全称为“Mutually Exclusive and Collectively Exhaustive”（独立不重叠，穷尽不遗漏），可以简单概括为“不重不漏”。

先说 ME （独立不重叠），是指写文章的时候，我们选择的信息应该是同一个层面上的，且它们之间相互不包含。这是非常基本的要求，与之前提到的“文章要简洁”也有着密切的关系。如果没有做到ME，就是没有做到信息层面的简洁。这意味着我们写分论点的时候，分论点与分论点之间要相互独立，不能一大一小地相互包含。如果发现自己写的第一个分论点和第二个分论点的分界不清不楚，两个段落的内容有交叉，就是没有做到ME，几个分论点的论证角度之间有重叠。

坚决不信速成扎实提高水平

最早源自麦肯锡在金字塔原理中提出的通用准则。

凡是你恶心的时候就是你进步的时候

需要说明的是，在托福考试中做到ME就符合了基本的考试要求。托福考试并不强求考生要做到CE，比如下面这两个例子：（1）题目说“只有有钱人才是成功的”，我们在反驳的时候罗列出因为其他原因成功的人就可以达到反驳的效果；（2）题目说“体育运动可以教会我们很多关于生活的东西（比如坚韧）”，我们如果选择同意，罗列几个有价值的点也是可以的。但是，如果能做到CE自然更优。托福作为一个语言考试，对论述强度并不做过分要求，但在GRE考试中，是绝对不允许忽视CE的，如果CE做不到，论述的强度就会被削弱。

而 CE （穷尽不遗漏）是指写文章的时候，我们必须把某个层面所包含的方方面面都讨论完，力求做到全面完整。例如，当我们在跟别人讨论问题时，很喜欢通过这样一句话来反驳对方：“我承认你所说的，但你是不是漏了方面A或者方面B呢？”也就是说，论证时如不能做到全面，就会产生明显的漏洞，就会留下靶子让别人打了。

我们尝试用MECE原则分析下面这个例子。

案 例 分 析

TEENAGE SMOKING

Ⅰ. Introduction

Ⅱ. Negative effect one is addiction, not habi

A. first fact related to addictio

B. second fact related to addiction

Ⅲ. Negative effect two is long-term health consequence

A. lung diseases

B. heart diseases

Ⅳ. Negative effect three is the cost to taxpayer

A. how much

B. why is this bad

Ⅴ. Conclusion

Express Yourself , Section 1, Chapter 2

这是针对“青少年吸烟”这一话题而列的提纲。第一段是“introduction”，给出明确的观点及其他具有介绍和引入性质的内容；第二段说青少年吸烟的危害之一是“会上瘾”，接着后面给出两个事实来进一步论证；第三段说危害之二是“长期来看，势必会影响身体健康”，然后具体讲一下肺部和心脏疾病；第四段说危害之三就是“ 会花费大量纳税人的钱 ”；第五段总结。大家认为这个提纲怎样？

的确，在考场上能在短时间内列出这样一个看似逻辑清楚、内容丰富的提纲已是不易，但是当各位接触并了解MECE原则之后，就应该用更严格的眼光来审视这个提纲，于是你会发现它一塌糊涂。因为它不符合MECE 原则，首先它没有做到ME，因为第一点和第二点所选择的信息不在同一个层面上；其次它也没做到CE，提纲中列举的三点涵盖的信息并不全面。

虽然内容比较丰富，但由于文章在组织和结构上的不合理，最终导致论证效果大打折扣。而如果保持主要内容不变，在文章的组织上稍加改动，它便能焕然一新，并且论证得更加严谨。首段和尾段一般来说都没有什么问题，我们主要关注文章论证的主体部分。第一个分论点改为“吸烟会对青少年的身体造成一定的危害”（此处用“肺部和心脏疾病”的相关内容来论述）；第二个分论点改为“吸烟会对青少年的精神造成一定的危害”（此处用“会上瘾”的相关内容来论述）；第三个分论点改为“除了对青少年本身有害，它也会对社会造成一定的危害”（此处用“花费大量纳税人的钱”的相关内容来论述）。也就是说特意分了几个层面，先指出吸烟对身体的负面影响；进而上升到精神层面的危害（这样“身体”和“精神”二者便形成了一种良好对应）；接下来又从个体扩展到集体，说明吸烟对其他社会群体造成的负担。这样的过渡更加合理，衔接更紧密，逻辑性也大大增强了。修改后的提纲如下所示：

Ⅰ. Introduction

Ⅱ. Negative effect one is individual physical proble

A. lung diseases

B. heart diseases

Ⅲ. Negative effect two is individual mental proble

A. addiction

B. mental decline

Ⅳ. Negative effect three is causing damage to the societ the cost to taxpayers

Ⅴ. Conclusion

坚决不信速成扎实提高水平

吸烟之所以会花费纳税人的钱，是因为吸烟很可能会导致疾病，而生病之后就会使用“社会保险”这一福利，这样就会花费大量纳税人的钱了。

凡是你恶心的时候就是你进步的时候

大家注意，这个例子尽管出现过，但现在我们要从另外一个不同的角度来看待这个例子。

这就是MECE原则的魅力所在，据此写出来的文章即使文字表达不够出彩，也至少能保证它是完整且全面的，这样算相当不错的了。即便有人不服，想与我争论，估计也很难找到漏洞或者破绽来进行反驳，只好悻悻然作罢。

对于这种改编，大家是怎样的感觉呢？与原始版本相比，重新组织之后的提纲确实全面多了。虽然两者在论据和内容上大同小异，但由于对信息做了分类和排列，所以显得完整，让人信服，无从指责。

这就是MECE原则的重要之处。当面对一个话题或观点时，相关论据不计其数，我们不可能全部罗列出来。但是要写出一篇不重不漏的文章，并且要在有限的字数内尽量把观点讨论清楚，就需要借助于MECE原则来对材料进行分类。

根据MECE原则，良好的分类首先是基于某个特定的层面的，而后再把该层面内的内容进行合理划分、归类。即先确定自己要讨论哪个范围的内容，而后根据条件分类，做到“不重不漏”，最后逐个阐述完毕就万事大吉了。可以说MECE原则是核心思想，而分类是方法和途径，良好的分类能很好地帮助我们写出一篇简洁、清楚、有条理的好文章。试想一下，如果没有任何的限定，讨论范围便无边无际了。毫不夸张地说，对于同一个话题，我可以从100个完全不一样的角度出发，构造100篇完全不一样的文章。不管你信还是不信，只要足够认真地思考可能引申的角度，就一定可以写出来。

“文勇老师，何苦为难自己呢？你这种行为太疯狂了，像是有强迫症似的。”

我之所以会那么说，是想引起大家足够的重视，注意讨论 之前先对讨论层面进行限定，并对材料进行分类，这样无论怎 样刁钻的题目，也逃不出我们的手掌心了。

下面我们再看一个例子吧。

It is the reality in society that it is becoming tougher for graduate students to find decent jobs. Therefore, preparations before their graduation are gaining significant attention. I maintain that preparations should be offered by colleges and universities before their students graduate because of the following three benefits for both sides.

First of all, universities are able to contact a variety of companies all over the country they are located in, or even big international firms, to hold an intern fair on campus so that students have more opportunities to choose. However,ordinary students without outstanding family background and social relations can hardly acquire this kind of chance by themselves, to meet so many companies at the same time and communicate directly with the employers. For example, the yearly internship fair is one of the most important events in United Universities. Almost all the junior students place great emphasis on it. According to the data from a career service center, the fair is really useful for students to find a good internship. If students have an outstanding performance during the intern, they are likely to be hired by the company when they obtain their degree. In this way, students can enjoy an advantage in their potential careers with their universities’ help.

In addition, universities should offer preparations since they have the responsibility to encourage students to practice rather than just learn and remember knowledge mechanically from textbooks. These career preparations are beneficial for students to accumulate work experiences and improve the ability of operational skills. For instance, according to the research from government, compared with students without preparations, the students who receive preparations before graduation have more practical abilities, which lead to a larger possibility to find a job in the competitive market. Those students can enjoy that advantage because they know more about the society than others. Apparently, the preparations provided by universities are necessary to students.

Furthermore, from the perspective of universities, if more students can get their jobs due to the preparations, this also contributes to the improvement of the image and reputation of the university in the society. Reputation, admit it or not,is always tightly linked with a university because it attracts more excellent students. For example, students always choose a university with good education system with an extensive platform, where it offers more opportunities. And preparations are regarded as a vital factor. Peking University has a superb reputation in China very much owing to its attention to students’ future. The instructions offered by Peking University appeal to students and parents. So, universities need to organize preparations.

坚决不信速成扎实提高水平

凡是你恶心的时候就是你进步的时候

To sum up, I agree with the statement that colleges and universities need to offer help to students prior to their graduation. Under the competitive circumstance in the jobmarket, universities can help students to acquire good jobs and improve their abilities. Meanwhile, career preparations are highly contributive to universities themselves.

学生原作

这是一篇学生习作，讨论的话题是“Colleges and universities should offer preparations for students before they graduat”（大学应该在学生毕业前为他们提供一些准备工作）。文章提纲提炼如下：

Ⅰ. Introduction

Ⅱ. Universities are capable enough to offer preparations for students

Ⅲ. Universities have the responsibility to offer preparations for students

Ⅳ. By offering their students preparations and helping them to find a good job, the university will gain reputation at the same time

Ⅴ. Conclusion

那么，这篇文章的框架是否合适呢？我们来根据MECE原则审视一下。首先，这篇文章是否做到了ME，即“独立不重叠”。第一个分论点说“大学有能力”，第二个分论点说“大学有责任”，第三个分论点说“对大学有利”。如此看来，ME的确做到了。其次，这篇文章是否做到了CE，即“穷尽不遗漏”。很明显，如这样的一个提纲所展示出来的，文章并没有做到CE，因为分论点的分类很模糊。在看到前面两个分论点都在说“大学如何如何”时，读者自然希望第三个分论点也是从同样的角度分析“大学如何如何”；同理，读者在看到文章的分论点是“对大学有益”时，也自然希望其他的分论点是“对学生有益”或者“对社会有益”。

从MECE原则的角度来看，这篇文章并不合格，因此这篇文章读起来给人的感觉不甚明了，像是拍脑袋突现灵感，即兴发挥而得的一样。这样的文章经不住推敲，也没有足够的力度说服读者。

那么应该怎样改进呢？首尾段不必多说，一般不会出现什么问题，我相信大家都能处理好。而需要重点考量的是论证主体的三个段落，即三个分论点。我倾向于把它们综合为三点：其一是对学生本身的好处——增加实习机会，锻炼实践能力等；其二是对社会的好处——提供高质量人才，提高生产力等；其三，也是最重要的，是对校方的好处——可提升其社会声誉及影响力。

尽管OG（官方指南）上要求大家列提纲，但是因为时间紧迫，大家往往不愿意这样做。可是不列提纲会容易导致分论点或分论点的展开过程在内容上有重叠或遗漏。要避免重叠和遗漏需要思维非常严谨，但同学们往往难以做到，于是推荐给大家一种做法：写段间过渡句，即在每一段开头写一句话，其前半句是对上段论点的重述，后半句是对本段论点的总结。这个做法能够帮助大家理清关系，不至于翻来覆去说同样的话。

让我们看以下两个例子：

One of the reasons I say this is that, even though in the past being able to handwrite or type out a good business letter for mailing was important, the actual volume of business writing is vastly more than in the past as businesses, suppliers,advertising and marketing agencies and customers exchange billions of emails and text messages. Clear, logical, correct,concise and succinct written communication is much more important because we must be able to say more with fewer words and we must do it much more often! The person who cannot write clearly and succinctly will not be successful no more than a person could in the past. Writing is still a basic requirement for success.

坚决不信速成扎实提高水平

凡是你恶心的时候就是你进步的时候

As for reading, if, as indicated above, more is being written then, of course, it is essential that we be able to read it more efficiently if we are to be successful There is much more to be read in modern times because, for instance, with the long distance communication that comes with globalization and doing business electronically in distant places, we do not have the simple local face-to-face verbal communication of past generations.

Now, huge number of contracts, proposals, studies, reports are sent via email which must be read quickly and correctly in order to make decisions and do business at any level.

《新托福真题详解——写作分卷（第一册）》

In the US, for example, students have much less homework and they spend their free time playing sports,participating in clubs, volunteering, and even having part-time jobs. From these activities, they learn many important life skills,such as teamwork, leadership, creative thinking, managing money, and being independent. They also get to experience fun,which is important because “all work and no play makes Jack a dull boy”. When they graduate from university, they are well-prepared for life. Chinese students, on the other hand,often find it difficult to adapt to the sudden chan.

However, the problem is not just the amount of daily homework; another issue is the inflexibility of daily homework.

Since the homework must be completed on a certain day, students are not able to organize their own schedules. From my point of view, homework should be set weekly and students should be given the freedom to plan their timetable. This will teach them responsibility and they will learn how to manage their time efficiently, which is a vital skill for any job. In summary, I believ that assigning daily homework prevents students from becoming mature and responsible.

《新托福真题详解——写作分卷（第一册）》

我们再来看一篇节选自托福阅读的文章。

案 例 分 析

PASSAGE EXCERPT: “From north to south in the Yucatan Peninsula, where the Maya lived, rainfall ranges from 18 to 100 inches (457 to 2,540 millimeters) per year, and the soils become thicker, so that the southern peninsula was agriculturally more productive and supported denser populations. But rainfall in the Maya homeland is unpredictably variable between years; some recent years have had three or four times more rain than other years. As a result,modern farmers attempting to grow corn in the ancient Maya homelands have faced frequent crop failures, especially in the north. The ancient Maya were presumably more experienced and did better, but nevertheless they too must have faced risks of crop failures from droughts and hurricanes.

Although southern Maya areas received more rainfall than northern areas, problems of water were paradoxically more severe in the wet south. While that made things hard for ancient Maya living in the south, it has also made things hard for modern archaeologists who have difficulty understandin why ancient droughts caused bigger problems in the wet south than in the dry north. The likely explanation is that an area of underground freshwater underlies the Yucatan Peninsula,but surface elevation increases from north to south, so that as one moves south the land surface lies increasingly higher above the water table. In the northern peninsula the elevation is sufficiently low that the ancient Maya were able to reach th water table at deep sinkholes called cenotes, or at deep caves.In low-elevation north coastal areas without sinkholes, the Maya would have been able to get down to the water table by digging wells up to 75 feet (22 meters) deep. But much of the south lies too high above the water table for cenotes or wells to reach down to it. Making matters worse, most of the Yucatan Peninsula consists of karst, a porous sponge-like limestone terrain where rain runs straight into the ground and where little or no surface water remains available.”

坚决不信速成扎实提高水平

凡是你恶心的时候就是你进步的时候

TPO-14: Maya Water Problems

MECE原则作为指导根据，可以使我们作出极具规律性和逻辑性的分类，并且帮助我们查漏补缺，审视各分论点之间的关系，从而在文章层面上实现有效的组织这一目标。

MECE原则强调了论证的逻辑性，实际上逻辑错误也是一个需要规避的问题，但托福写作对这一点的要求并不是很严格，感兴趣的考生可以阅读《GRE百日百句百题——写作题库全解析》前面的理论部分。 LAfBr02jE5Q7qrGmKC3CcxU618w22+YCEiYUSdSjz+4jF9Z3rf1okHjilfg3un8j