1、Every field of study has its own language and its own way of thinking. Mathematicians talk about axioms, integrals, and vector spaces. Psychologists talk about ego, id, and cognitive dissonance. Lawyers talk about venue, torts, and promissory estoppel. 每个 研究领域都有它自己的语言和思考方式。数学家谈论定理、积分以及向量空间。心理学家谈论自我、
2、本能、以及认知的不一致性。律师谈论犯罪地点、侵权行为以及约定的禁止翻供。 Economics is no different. Supply, demand, elasticity, comparative advantage, consumer surplus, deadweight lossthese terms are part of the economists language. In the coming chapters, you will encounter many new terms and some familiar words that economists use i
3、n specialized ways. At first, this new language may seem needlessly arcane. But, as you will see, its value lies in its ability to provide you a new and useful way of thinking about the world in which you live. 经济学家也一样。供给、需求、弹性、比较优势、消费剩余、最低损耗，这些术语是经济学语言的一部分。在接下来的章节里，你会遇到很多新术语以及一些熟悉的词汇，这些术语和词汇被经济学家们用
4、在经济这一领域。起初，这些新的语言可能看起来不必要的神秘，但是，你会看到，他的价值在于他能提供给你一种新的和有用的思考方式，让你思考你生活的世界。 The single most important purpose of this book is to help you learn the economists way of thinking. Of course, just as you cannot become a mathematician, psychologist, or lawyer overnight, learning to think like an economist w
5、ill take some time. Yet with a combination of theory, case studies, and examples of economics in the news, this book will give you ample opportunity to develop and practice this skill. 这本书唯一的最重要的目的就是帮助你学习经济学家的思考方式。当然，就像你不能一夜就成为数学家、心理学家或者律师一样，学会像经济学家一样思考会花费一定的时间。然而，在理论、案例研究、以及经济新闻的案例的结合下，这本书将会给你充分的机会
6、来发展和练习这种能力。 Before delving into the substance and details of economics, it is helpful to have an overview of how economists approach the world. This chapter, therefore, discusses the fields methodology. What is distinctive about how economists confront a question? What does it mean to think like an
7、economist? 在探究经济学的实质和细节前，对经济学家们如何看待世界进行预览是非常有益的。因此，这一章讨论了这一领域的方法论。经济学家解决问题有何独特之处？像经济学家一样思考是什么意思？ THE ECONOMIST AS SCIENTIST 作为科学家的经济学家 Economists try to address their subject with a scientists objectivity. They approach the study of the economy in much the same way as a physicist approaches the stud
8、y of matter and a biologist approaches the study of life: They devise theories, collect data, and then analyze these data in an attempt to verify or refute their theories. 经济学家们试图从科学的角度来阐释他们的学科。他们演绎经济学和物理学家演绎物质、生物学家演绎生命一样：他们设计理论，收集数据，然后分析这些数据，试图能够证明或者反驳他们的理论。 To beginners, it can seem odd to claim t
9、hat economics is a science. After all, economists do not work with test tubes or telescopes. The essence of science, however, is the scientific methodthe dispassionate development and testing of theories about how the world works. This method of inquiry is as applicable to studying a nations economy
10、 as it is to studying the earths gravity or a species evolution. As Albert Einstein once put it, “The whole of science is nothing more than the refinement of everyday thinking.” 对于初学者来说，宣称经济学是科学似乎看起来很奇怪。毕竟，经济学家们并不和试管或者显微镜一起工作。然而，科学的精华是科学的方法 世界如何运作这一理论的逐渐发展和试验。这种观察的方法运用于研究一个国家的经济，就像它运用于研究地球 的重力或者一个物种
11、的 演变。就像爱因斯坦曾经提出的：科学的全部无非就是日常思考的精炼。 Although Einsteins comment is as true for social sciences such as economics as it is for natural sciences such as physics, most people are not accustomed to looking at society through the eyes of a scientist. Lets therefore discuss some of the ways in which economi
12、sts apply the logic of science to examine how an economy works. 尽管爱因斯坦的观点对于社会科学例如经济学是正确的， 就像它对于自然科学例如物理学一样是正确的，大部分人并不习惯于通过科学的角度来看待社会。因此，就让我们来讨论一些方法，通过这些方法，经济学家们运用科学逻辑来观察经济如何运作。 THE SCIENTIFIC METHOD: OBSERVATION, THEORY, AND MORE OBSERVATION 科学的方法：观察、理论以及更多的观察 Isaac Newton, the famous seventeenth-ce
13、ntury scientist and mathematician, allegedly became intrigued one day when he saw an apple fall from an apple tree. This observation motivated Newton to develop a theory of gravity that applies not only to an apple falling to the earth but to any two objects in the universe. Subsequent testing of Ne
14、wtons theory has shown that it works well in many circumstances (although, as Einstein would later emphasize, not in all circumstances). Because Newtons theory has been so successful at explaining observation, it is still taught today in undergraduate physics courses around the world. 牛顿， 17 世纪著名的科学
15、家和数学家，当有一天看到一个苹果从树上掉下时，引起了他的深思。这个观察使牛顿形成了重力的理论，这一理论不仅应用于苹果落地，而且应用于宇宙中的任何两个物体之间。牛顿定律的不断试验表明，它适用于很多情况（尽管爱因斯坦后来强调并不是适用于所有的情况）。由于牛顿定律在解释试验时很成功，所以今天它仍然在世界各个大学的物理课程中被学习。 This interplay between theory and observation also occurs in the field of economics. An economist might live in a country experiencing r
16、apid increases in prices and be moved by this observation to develop a theory of inflation. The theory might assert that high inflation arises when the government prints too much money. (As you may recall, this was one of the Ten Principles of Economics in Chapter 1.) To test this theory, the econom
17、ist could collect and analyze data on prices and money from many different countries. If growth in the quantity of money were not at all related to the rate at which prices are rising, the economist would start to doubt the validity of his theory of inflation. If money growth and inflation were stro
18、ngly correlated in international data, as in fact they are, the economist would become more confident in his theory. 现象和理论的这一关系也同样发生在经济领域。经济学家可能生活在这样的国家，这个国家的物价正在迅速增长，在这一现象的推动下，经济学家发现了关于通货膨胀的理论。这一理论可能宣称：当政府印制太多货币时，高的通货膨胀就会出现（你可能会想起，这是第一章中十条经济学原理之一）。为了验证这一理论，经济学家会从不同国家收集并分析关于价格和货币量的数据。如果货币量的增长和价格膨胀率根
19、本不相关，经济学家就会开始怀疑通货膨胀理论的正确性。如果数据表明货币增长量和通胀高度相关，经济学家就会对他的理论更加有信心。 Although economists use theory and observation like other scientists, they do face an obstacle that makes their task especially challenging: Experiments are often difficult in economics. Physicists studying gravity can drop many objects
20、in their laboratories to generate data to test their theories. By contrast, economists studying inflation are not allowed to manipulate a nations monetary policy simply to generate useful data. Economists, like astronomers and evolutionary biologists, usually have to make do with whatever data the w
21、orld happens to give them. 尽管经济学家像其他科学家一样应用理论和现象，他们确实面临一个障碍：在经济学中做试验往往很困难，这一障碍使他们的工作更具挑战性。物理学家研究向心力可以在实验室里降落许多物体来产生数据以测试他们的理论。相比之下，经济学家研究通货膨胀不可以仅仅为了产生有用的数据，而去操纵一个国家的货币政策。像宇宙学家和生物学家一样，一般来说经济学家不得不运用世界已经发生的数据来做试验。 To find a substitute for laboratory experiments, economists pay close attention to the na
22、tural experiments offered by history. When a war in the Middle East interrupts the flow of crude oil, for instance, oil prices skyrocket around the world. For consumers of oil and oil products, such an event depresses living standards. For economic policymakers, it poses a difficult choice about how
23、 best to respond. But for economic scientists, it provides an opportunity to study the effects of a key natural resource on the worlds economies, and this opportunity persists long after the wartime increase in oil prices is over. Throughout this book, therefore, we consider many historical episodes
24、. These episodes are valuable to study because they give us insight into the economy of the past and, more important, because they allow us to illustrate and evaluate economic theories of the present. 为了找到实验室试验的替代实验，经济学家密切关注于由历史提供的自然实验。例如，当中东的一次战争打断了原油的供应，石油价格在全球范围狂涨。对于石油及石油生产品的消费者来说，这样的一次事件降低了生活水平。
25、对于经济决策者，如何让应对这样的事件，给他们出了一道难题。但是对于经济科学家来说，它为重要自然资源对于世界经济的影响的研究提供了一次机会，这次机会持续很久，直到石油价格增长的战争时间结束。因此，整本书中，我们会分析很多历史事件。这些历史事件很值得研究，因为，他们让我们对过去的经济有了大概的了解，更重要的是因为他们 可以让我们对过去的经济理论进行阐释和评价。 THE ROLE OF ASSUMPTIONS 假设的重要性 If you ask a physicist how long it would take for a marble to fall from the top of a ten-
26、story building, she will answer the question by assuming that the marble falls in a vacuum. Of course, this assumption is false. In fact, the building is surrounded by air, which exerts friction on the falling marble and slows it down. Yet the physicist will correctly point out that friction on the
27、marble is so small that its effect is negligible. Assuming the marble falls in a vacuum greatly simplifies the problem without substantially affecting the answer. 如果你问一个物理学家一块大理石从十层高的大楼顶层落下，需要多长时间，她回答这个问题会假定大理石在真空中落下。当然，这个假设是错误的。事实上，这个大楼被空气环绕，空气会对大理石降落产生摩擦力，并减慢他的速度。然而物理学家会指出：空气对大理石的摩擦力太小以致它的影响可以忽略。假
28、定大理石在真空中降落，并且几乎没有影响答案，大大简化了问题。 Economists make assumptions for the same reason: Assumptions can make the world easier to understand. To study the effects of international trade, for example, we may assume that the world consists of only two countries and that each country produces only two goods. Of
29、 course, the real world consists of dozens of countries, each of which produces thousands of different types of goods. But by assuming two countries and two goods, we can focus our thinking. Once we understand international trade in an imaginary world with two countries and two goods, we are in a be
30、tter position to understand international trade in the more complex world in which we live. 经济学家作假设基于相同的原因：假设能够使世界更容易理解。例如，为了研究国际交易的影响，我们可以假设世界仅有两个国家，并且每个国家仅仅生产两种产品。当然，现实的世界有很多国家组成，每个国家生产上千种不同的产品。但是通过假设两个国家和两种产品，我们可以更好的思考。一旦我们理解了假设中的两个国家两种产品的国际交易，那么我们可以更好地理解我们生活的这一更加复杂的世界的国际交易。 The art in scientific
31、 thinkingwhether in physics, biology, or economicsis deciding which assumptions to make. Suppose, for instance, that we were dropping a beach ball rather than a marble from the top of the building. Our physicist would realize that the assumption of no friction is far less accurate in this case: Fric
32、tion exerts a greater force on a beach ball than on a marble. The assumption that gravity works in a vacuum is reasonable for studying a falling marble but not for studying a falling beach ball. 科学思考的艺术，不论是在物理学、生物学或者经济学上，取决于做什么样的假设。例如，假定从楼顶上落下的是沙滩排球而不是大理石。我们的物理学家就会认识到没有摩擦力的假设在这种情况下是很不精确的：比起空气对大理石的摩擦
33、，空气对沙滩排球的摩擦会产生更大的力。重力在真空中作用这一假设对于研究降落的大理石来说是合理的，但是对于研究沙滩排球就不合理。 Similarly, economists use different assumptions to answer different questions. Suppose that we want to study what happens to the economy when the government changes the number of dollars in circulation. An important piece of this analys
34、is, it turns out, is how prices respond. Many prices in the economy change infrequently; the newsstand prices of magazines, for instance, are changed only every few years. Knowing this fact may lead us to make different assumptions when studying the effects of the policy change over different time horizons. For studying the short-run effects of the policy, we may assume that prices do not change much. We may even make the extreme and artificial assumption that all prices are completely fixed. For studying the long-run effects of the
