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、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 loss—these terms are part of the economist’s language. In the coming chapters, you will encounter many new terms and some familiar words that economists use in 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 economist’s way of thinking. Of course, just as you cannot become a mathematician, psychologist, or lawyer overnight, learning to think like an economist will 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 field’s methodology. What is distinctive about how economists confront a question? What does it mean to think like an 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 scientist’s objectivity. They approach the study of the economy in much the same way as a physicist approaches the study 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 that economics is a science. After all, economists do not work with test tubes or telescopes. The essence of science, however, is the scientific method—the dispassionate development and testing of theories about how the world works. This method of inquiry is as applicable to studying a nation’s economy as it is to studying the earth’s 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 Einstein’s 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. Let’s therefore discuss some of the ways in which economists 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-century 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 Newton’s theory has shown that it works well in many circumstances (although, as Einstein would later emphasize, not in all circumstances). Because Newton’s 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 rapid 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 economist 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 strongly 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 in their laboratories to generate data to test their theories. By contrast, economists studying inflation are not allowed to manipulate a nation’s monetary policy simply to generate useful data. Economists, like astronomers and evolutionary biologists, usually have to make do with whatever data the world 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 natural 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 best to respond. But for economic scientists, it provides an opportunity to study the effects of a key natural resource on the world’s economies, and this opportunity persists long after the wartime increase in oil prices is over. Throughout this book, therefore, we consider many historical episodes. 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。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-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 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 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 better 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 thinking—whether in physics, biology, or economics—is 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: Friction 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，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 analysis, 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 policy, however, we may assume that all prices are completely flexible. Just as a physicist uses different assumptions when studying falling marbles and falling beach balls, economists use different assumptions when studying the short-run and long-run effects of a change in the quantity of money.

相似地，经济学家用不同的假设来回答不同的问题。假设我们要研究当政府改变流通中的货币时，会对经济产生什么样的影响。结果表明，这个分析很重要的一条是价格是如何回应的。经济中很多价格会经常变动，报摊上的杂志价格变动会隔几年。懂得这一事实，可以让我们在研究不同时期政策改变的影响时，做出不同的假设。对于研究政策的短期影响时，我们可以假设价格不会变动很大。我们甚至可以做极端人为的假设——所有价格都完全不变。然而，对于研究政策的长期影响，我们可以假设所有价格都是完全弹性的。就像物理学家研究大理石降落和沙滩排球降落用不同的假设一样，经济学家在研究货币量变化的短期和长期影响时，用不同的假设。

ECONOMIC MODELS经济模型

High school biology teachers teach basic anatomy with plastic replicas of the human body. These models have all the major organs—the heart, the liver, the kidneys, and so on. The models allow teachers to show their students in a simple way how the important parts of the body fit together. Of course, these plastic models are not actual human bodies, and no one would mistake the model for a real person. These models are stylized, and they omit many details. Yet despite this lack of realism—indeed, because of this lack of realism—studying these models is useful for learning how the human body works.

高中生物老师用人体的塑料复制品讲授基础解剖学。这些模型都有主要的器官：心脏、肝脏、肾脏等等。这些模型让老师用简单的方式展示给他们的学生身体上这些重要的部分是如何互相协调的。当然，这些塑料模型不是真实的人体，没有人会把这些模型误认为是真的人。这些模型是设计的，他们忽略了很多细节。然而，尽管缺乏真实性，但是正是对这些模型的研究，对学习人体如何工作很有帮助。

Economists also use models to learn about the world, but instead of being made of plastic, they are most often composed of diagrams and equations. Like a biology teacher’s plastic model, economic models omit many details to allow us to see what is truly important. Just as the biology teacher’s model does not include all of the body’s muscles and capillaries, an economist’s model does not include every feature of the economy.

经济学家也用模型来学习世界，但是他们通常用图表和等式，而不是制作塑料复制品。就像一个生物老师的塑料模型，经济模型忽略了很多细节，这些细节可以让我们看到什么是真正重要的。就像生物老师的模型不包括人体所有的肌肉和毛细血管一样，经济学家的模型不包括经济的每个特征。

As we use models to examine various economic issues throughout this book, you will see that all the models are built with assumptions. Just as a physicist begins the analysis of a falling marble by assuming away the existence of friction, economists assume away many of the details of the economy that are irrelevant for studying the question at hand. All models—in physics, biology, or economics— simplify reality in order to improve our understanding of it.

整本书中我们用模型来解决不同的经济问题，你会看到所有的模型都是基于一定的假设。就像物理学家对下落的大理石假设不存在摩擦力进行分析一样，经济学家假设忽略了很多与问题研究不相关的细节。所有的模型不论是物理、生物、还是经济学，都简化了现实，以提高我们对问题的理解。

OUR FIRST MODEL: THE CIRCULAR-FLOW DIAGRAM

第一个模型：循环流向图

The economy consists of millions of people engaged in many activities—buying, selling, working, hiring, manufacturing, and so on. To understand how the economy works, we must find some way to simplify our thinking about all these activities. In other words, we need a model that explains, in general terms, how the economy is organized and how participants in the economy interact with one another.

经济由成千上万的人组成，这些人参加很多活动：购买、销售、工作、雇佣、制造等等。为了理解经济如何工作，我们必须找到一种方法来简化我们对这些活动的思考。换句话说，我们需要一个模型，这个模型能够用普通词汇解释经济是如何组织的，经济的参加者是如何相互影响的。

Figure 2-1 presents a visual model of the economy, called a circular-flow diagram. In this model, the economy has two types of decision-makers—households and firms. Firms produce goods and services using inputs, such as labor, land, and capital (buildings and machines). These inputs are called the factors of production. Households own the factors of production and consume all the goods and services that the firms produce.

图2-1展示了经济的一个可视化模型，被称为循环流向图。在这个模型中，经济有两种类型的决策者：家庭和公司。公司通过劳动、土地及资本（大楼和机器）的输入来生产货物和服务。这些输入被称为生产因素。家庭拥有生产要素并且消费公司生产的所有货物和服务。

Households and firms interact in two types of markets. In the markets for goods and services, households are buyers and firms are sellers. In particular, households buy the output of goods and services that firms produce. In the markets for the factors of production, households are sellers and firms are buyers. In these markets, households provide firms the inputs that the firms use to produce goods and services. The circular-flow diagram offers a simple way of organizing all the economic transactions that occur between households and firms in the economy.

家庭和公司在两种类型的市场上互相影响。在货物和服务市场上，家庭是购买者，公司是卖者。特别的是，家庭购买公司生产并输出的货物和服务。在生产要素市场上，家庭是卖者，公司是买者。在这些市场上，家庭提供公司生产货物和服务的输入原料。这个循环流向图提供家庭和公司之间组织经济交易的一种简单方式。

The inner loop of the circular-flow diagram represents the flows of goods and services between households and firms. The households sell the use of their labor, land, and capital to the firms in the markets for the factors of production. The firms then use these factors to produce goods and services, which in turn are sold to households in the markets for goods and services. Hence, the factors of production flow from households to firms, and goods and services flow from firms to households.

循环流向图的里面一圈代表家庭和公司间货物和服务的流动。家庭把他们的劳动、土地及资本卖给公司，以作为公司的生产要素。然后公司用这些要素来生产货物和服务，反过来又把这些货物和服务在市场上卖给家庭。因此，生产要素从家庭流动到公司，货物和服务从公司流动到家庭。

The outer loop of the circular-flow diagram represents the corresponding flow of dollars. The households spend money to buy goods and services from the firms. The firms use some of the revenue from these sales to pay for the factors of production, such as the wages of their workers. What’s left is the profit of the firm owners, who themselves are members of households. Hence, spending on goods and services flows from households to firms, and income in the form of wages, rent, and profit flows from firms to households.

循环流向图的外面一层代表相应的现金流。家庭花费钱从公司购买货物和服务。公司用这些从销售中获得的收入来支付生产要素，例如工人的工资。剩余的就是公司所有者的利润，公司所有者本身就是家庭的成员。因此，花费在货物和服务上的现金流从家庭流到公司，收入以工资、租金和利润的形式从公司流到家庭。

Let’s take a tour of the circular flow by following a dollar bill as it makes its way from person to person through the economy. Imagine that the dollar begins at a household, sitting in, say, your wallet. If you want to buy a cup of coffee, you take the dollar to one of the economy’s markets for goods and services, such as your local Starbucks coffee shop. There you spend it on your favorite drink. When the dollar moves into the Starbucks cash register, it becomes revenue for the firm. The dollar doesn’t stay at Starbucks for long, however, because the firm uses it to buy inputs in the markets for the factors of production. For instance, Starbucks might use the dollar to pay rent to its landlord for the space it occupies or to pay the wages of its workers. In either case, the dollar enters the income of some household and, once again, is back in someone’s wallet. At that point, the story of the economy’s circular flow starts once again.

让我们来跟踪一美元在经济中是如何从一个人流动到另一个人的。想象一下这一美元来自一个家庭，坐在这里说，你的钱包。如果你想买一杯咖啡，你会拿着钱去其中的一个经济市场上去买货物和服务，例如当地星巴克咖啡店。在那里，你买你喜欢的饮料。当美元流进星巴克的钱柜时，它变成了公司的收入。然而，钱不会在星巴克停留很长时间，这是因为公司用它来从市场上购入生产要素。例如，星巴克可能会用钱来支付出租人的租金，或者用来支付工人的工资。在其他情况下，美元成为一些家庭的收入，并且，又一次，返回某个人的钱包。在这一点，经济流动循环的故事又重新开始。

The circular-flow diagram in Figure 2-1 is one simple model of the economy. It dispenses with details that, for some purposes, are significant. A more complex and realistic circular-flow model would include, for instance, the roles of government and international trade. Yet these details are not crucial for a basic understanding of how the economy is organized. Because of its simplicity, this circular-flow diagram is useful to keep in mind when thinking about how the pieces of the economy fit together.

图2-1中的循环流向图是经济中一个很简单的模型。它为了一定的目的而忽略了细节是有意义的。一个更加复杂和现实的流动循环模型会包括政府和国际交易。然而这些细节对于理解经济如何运作并不重要。由于它的简单性，当人们在思考经济的每一部分是如何协调运作时，记住这个循环流向图很有用。

Figure 2-1图2-1

THE CIRCULAR FLOW. This diagram is a schematic representation of the organization of the economy. Decisions are made by households and firms. Households and firms interact in the markets for goods and services (where households are buyers and firms are sellers) and in the markets for the factors of production (where firms are buyers and households are sellers). The outer set of arrows shows the flow of dollars, and the inner set of arrows shows the corresponding flow of goods and services.

循环流动图。这个图是组织经济的扼要描述。家庭和公司制定决策。家庭和公司在产品市场（在这个市场上家庭是购买者，公司是卖者）和生产要素市场（在这个市场上公司是买者，家庭是卖者）上互相作用。外面一系列箭头展示了现金的流动，里面的箭头展示了相应的产品流动。

OUR SECOND MODEL: THE PRODUCTION POSSIBILITIES FRONTIER

第二个模型：生产可能性边界

Most economic models, unlike the circular-flow diagram, are built using the tools of mathematics. Here we consider one of the simplest such models, called the production possibilities frontier, and see how this model illustrates some basic economic ideas.

大部分经济模型，不像循环流向图，是通过数学工具建立的。这里我们思考最简单的一个模型，叫做生产可能性边界，来看一下模型是如何解释基本的经济观念的。

Although real economies produce thousands of goods and services, let’s imagine an economy that produces only two goods—cars and computers. Together the car industry and the computer industry use all of the economy’s factors of production. The production possibilities frontier is a graph that shows the various combinations of output—in this case, cars and computers—that the economy can possibly produce given the available factors of production and the available production technology that firms can use to turn these factors into output.

尽管真实的经济生产成千上万中产品，让我们假设一种仅生产汽车和计算机这两种产品的经济。汽车工业和计算机工业使用了所有的经济生产要素。这个生产可能性区域图展示了各种输出的组合（在这种情况下，是经济可能生产的汽车和计算机），在给定的生产要素条件下和可能的生产技术条件下，公司使用这些要素并将其转换成为输出。

Figure 2-2 is an example of a production possibilities frontier. In this economy, if all resources were used in the car industry, the economy would produce 1,000 cars and no computers. If all resources were used in the computer industry, the economy would produce 3,000 computers and no cars. The two end points of the production possibilities frontier represent these extreme possibilities. If the economy were to divide its resources between the two industries, it could produce 700 cars and 2,000 computers, shown in the figure by point A. By contrast, the outcome at point D is not possible because resources are scarce: The economy does not have enough of the factors of production to support that level of output. In other words, the economy can produce at any point on or inside the production possibilities frontier, but it cannot produce at points outside the frontier.

图2-2是生产可能性边界的一个例子。在这个经济中，如果汽车工业使用了所有的资源，经济能够生产1000辆汽车，没有计算机。如果计算机工业使用了所有的资源，经济会生产3000台计算机，没有汽车。生产可能性边界的两个端点代表了极端可能性。如果经济要将它的资源分配到两个工业上，它能够生产700辆汽车和2000台电脑，图中的A点就是这种情况。相形之下，D点的生产是不可能的，因为资源是稀缺的。经济没有足够的生产要素来支持这个输出水平。换句话说，经济能够生产可能性边界上的点以及里面的点，但是不能生产边际外的点。

An outcome is said to be efficient if the economy is getting all it can from the scarce resources it has available. Points on (rather than inside) the production possibilities frontier represent efficient levels of production. When the economy is producing at such a point, say point A, there is no way to produce more of one good without producing less of the other. Point B represents an inefficient outcome. For some reason, perhaps widespread unemployment, the economy is producing less than it could from the resources it has available: It is producing only 300 cars and 1,000 computers. If the source of the inefficiency were eliminated, the economy could move from point B to point A, increasing production of both cars (to 700) and computers (to 2,000).

如果经济可以利用它所得到的全部稀缺资源，那么这个结果就是有效率的。生产可能性边界上的点（而不是里面的点）代表了生产水平的有效性。当经济在这一点生产时，如A点，是没有办法实现生产更多一种产品，除非少生产另一种产品。B点代表了一种无效的结果。由于某些原因，可能是大范围的失业，经济生产水平低于它能够生产的水平。它仅能生产300辆车1000台计算机。如果消除无效的资源，经济能够从B点移到A点，增加汽车和计算机的产量。（汽车700辆，计算机2000台）。

One of the Ten Principles of Economics discussed in Chapter 1 is that people face tradeoffs. The production possibilities frontier shows one tradeoff that society faces. Once we have reached the efficient points on the frontier, the only way of getting more of one good is to get less of the other. When the economy moves from point A to point C, for instance, society produces more computers but at the expense of producing fewer cars.

第一章讨论的经济学十大原理之一是人们面临权衡。生产可能性边界表明社会面临的权衡。如果我们已经达到边际上的有效点，更多的生产一种产品的唯一方法是少生产另一种。例如，当经济从A点移到C点时，社会会生产更多的计算机，但是同时必须少生产汽车。

Another of the Ten Principles of Economics is that the cost of something is what you give up to get it. This is called the opportunity cost. The production possibilities frontier shows the opportunity cost of one good as measured in terms of the other good. When society reallocates some of the factors of production from the car industry to the computer industry, moving the economy from point A to point C, it gives up 100 cars to get 200 additional computers. In other words, when the economy is at point A, the opportunity cost of 200 computers is 100 cars.

经济学十大原理的另一个是一些东西的成本是你为了得到这些东西而放弃的东西。这被成为机会成本。生产可能性边界表明一种货物的机会成本是以另一种货物来衡量的。当社会从汽车工业到计算机工业重新分配一些生产要素时，即从A点移到C的点，它放弃了100辆汽车，为了200台额外的计算机。换句话说，当经济在A点时，200台计算机的机会成本是100辆汽车。

Notice that the production possibilities frontier in Figure 2-2 is bowed outward. This means that the opportunity cost of cars in terms of computers depends on how much of each good the economy is producing. When the economy is using most of its resources to make cars, the production possibilities frontier is quite steep. Because even workers and machines best suited to making computers are being used to make cars, the economy gets a substantial increase in the number of computers for each car it gives up. By contrast, when the economy is using most of its resources to make computers, the production possibilities frontier is quite flat. In this case, the resources best suited to making computers are already in the computer industry, and each car the economy gives up yields only a small increase in the number of computers.

请注意图2-2中生产可能性边界是向外凸的。这意味着，汽车及计算机的机会成本取决于经济生产每个货物的数量。当经济用它大部分资源来生产小汽车时，生产可能性边界是很陡的。这是因为即使最擅长制造计算机的工人和机器来制造汽车，经济会在计算机数量上得到相应增加，为了它放弃的每辆汽车。相反，当经济用它大部分资源来生产计算机，生产可能性边界则很平缓。在这种情况下，最擅长制造计算机的资源已经在计算机工业，经济放弃的每辆汽车仅仅增加生产很少数量的计算机。

The production possibilities frontier shows the tradeoff between the production of different goods at a given time, but the tradeoff can change over time. For example, if a technological advance in the computer industry raises the number of computers that a worker can produce per week, the economy can make more computers for any given number of cars. As a result, the production possibilities frontier shifts outward, as in Figure 2-3. Because of this economic growth, society might move production from point A to point E, enjoying more computers and more cars.

生产可能性边界表明一定时期不同货物之间生产的权衡，但是权衡会随时间改变。例如，如果计算机工业技术的提高增加了工人每周能够生产计算机的数量，在给定的汽车数量下，经济能够制造更多的计算机。结果，生产可能性边界向外移动，如图2-3。由于经济增长，社会可能将生产量从A点移到E点，偏好更多的计算机和小汽车。

The production possibilities frontier simplifies a complex economy to highlight and clarify some basic ideas. We have used it to illustrate some of the concepts mentioned briefly in Chapter 1: scarcity, efficiency, tradeoffs, opportunity cost, and economic growth. As you study economics, these ideas will recur in various forms. The production possibilities frontier offers one simple way of thinking about them.

生产可能性边界简化了复杂的经济，而强调并将一些基本思想分类。我们已经用它来解释第一章提到的一些概念：稀缺性、有效性、权衡、机会成本以及经济增长。当你学习经济学时，这些思想将会以不同的形式再次出现。生产可能性边界提供了一种简单的方式来思考他们。

Figure 2-2

THE PRODUCTION POSSIBILITIES FRONTIER. The production possibilities frontier shows the combinations of output—in this case, cars and computers—that the economy can possibly produce. The economy can produce any combination on or inside the frontier. Points outside the frontier are not feasible given the economy’s resources.

生产可能性边界。生产可能性边界展示了经济能够生产的产量的组合，在这种情况下，产量是汽车和计算机。经济能够生产边界上的以及边界里面的任何一种组合。在给定经济资源的条件下，边界线外面的所有点都是不可行的。

Figure 2-3

A SHIFT IN THE PRODUCTION POSSIBILITIES FRONTIER. An economic advance in the computer industry shifts the production possibilities frontier outward, increasing the number of cars and computers the economy can produce.

生产可能性边界的移动。计算机工业的经济提高使生产可能性边界向外移动，使经济能够生产的汽车和计算机的数量增加。

合同管理制度

1 范围

本标准规定了龙腾公司合同管理工作的管理机构、职责、合同的授权委托、洽谈、承办、会签、订阅、履行和变更、终止及争议处理和合同管理的处罚、奖励；

本标准适用于龙腾公司项目建设期间的各类合同管理工作，厂内各类合同的管理，厂内所属各具法人资格的部门，参照本标准执行。

2 规范性引用

《中华人民共和国合同法》

《龙腾公司合同管理办法》

3 定义、符号、缩略语

无

4 职责

4.1 总经理：龙腾公司经营管理的法定代表人。负责对厂内各类合同管理工作实行统一领导。以法人代表名义或授权委托他人签订各类合法合同，并对电厂负责。

4.2 工程部：是发电厂建设施工安装等工程合同签订管理部门；负责签订管理基建、安装、人工技术的工程合同。

4.3 经营部：是合同签订管理部门，负责管理设备、材料、物资的订购合同。

4.5 合同管理部门履行以下职责：

4.5.1 建立健全合同管理办法并逐步完善规范；

4.5.2 参与合同的洽谈、起草、审查、签约、变更、解除以及合同的签证、公证、调解、诉讼等活动，全程跟踪和检查合同的履行质量；

4.5.3 审查、登记合同对方单位代表资格及单位资质，包括营业执照、经营范围、技术装备、信誉、越区域经营许可等证件及履约能力（必要时要求对方提供担保），检查合同的履行情况；

4.5.4 保管法人代表授权委托书、合同专用章，并按编号归口使用；

4.5.5 建立合同管理台帐，对合同文本资料进行编号统计管理；

4.5.6 组织对法规、制度的学习和贯彻执行，定期向有关领导和部门报告工作；

4.5.7 在总经理领导下，做好合同管理的其他工作，

4.6 工程技术部：专职合同管理员及材料、燃料供应部兼职合同管理员履行以下职责：

4.6.1 在主任领导下，做好本部门负责的各项合同的管理工作，负责保管“法人授权委托书”；

4.6.2 签订合同时，检查对方的有关证件，对合同文本内容依照法规进行检查，检查合同标的数量、金额、日期、地点、质量要求、安全责任、违约责任是否明确，并提出补充及修改意见。重大问题应及时向有关领导报告，提出解决方案；

4.6.3 对专业对口的合同统一编号、登记、建立台帐，分类整理归档。对合同承办部门提供相关法规咨询和日常协作服务工作；

4.6.4 工程技术部专职合同管理员负责收集整理各类合同，建立合同统计台帐，并负责

thinking like an economist翻译