曼昆《经济学原理》2-3(English Version).ppt

Copyright © 2004 South-Western/Thomson Learning2Thinking Like an EconomistCopyright © 2004 South-Western/Thomson Learning•主要内容：主要内容：经济学的研究方法 （科学研究/政策研究） •重点：重点：生产可能性曲线（PPF）的特征、经济学意义及应用•学完本章后，你学完本章后，你应该：：•了解经济学的基本假设•掌握两个基本的经济学模型•能够用PPF解释稀缺性、效率、权衡取舍、机会成本、经济增长等5个概念•能够用PPF说明贸易的好处Copyright © 2004 South-Western/Thomson LearningThinking Like an Economist•Every field of study has its own terminology•Economics trains you to. . . . •Think in terms of alternatives.•Evaluate the cost of individual and social choices.•Examine and understand how certain events and issues are related.•The economic way of thinking . . .•Involves thinking analytically and objectively.•Makes use of the scientific method.Copyright © 2004 South-Western/Thomson LearningThe Scientific Method: Observation, Theory, and More Observation•Uses abstract models to help explain how a complex, real world operates.•Develops theories, collects, and analyzes data to evaluate the theories.Copyright © 2004 South-Western/Thomson LearningThe Role of Assumptions• Economists make assumptions in order to make the world easier to understand.• The art in scientific thinking is deciding which assumptions to make.• Economists use different assumptions to answer different questions.Copyright © 2004 South-Western/Thomson LearningEconomic Models• Economists use models to simplify reality in order to improve our understanding of the world• Two of the most basic economic models include:•The Circular Flow Diagram•The Production Possibilities FrontierCopyright © 2004 South-Western/Thomson LearningOur First Model: The Circular-Flow Diagram•The circular-flow diagram is a visual model of the economy that shows how dollars flow through markets among households and firms.Figure 1 The Circular FlowCopyright © 2004 South-WesternSpendingGoods andservicesboughtRevenueGoodsand servicessoldLabor, land,and capitalIncome = Flow of inputs and outputs = Flow of dollarsFactors ofproductionWages, rent,and profit FIRMS•Produce and sellgoods and services•Hire and use factorsof production •Buy and consumegoods and services•Own and sell factorsof productionHOUSEHOLDS •Households sell•Firms buyMARKETSFORFACTORS OF PRODUCTION •Firms sell•Households buyMARKETSFORGOODS AND SERVICESCopyright © 2004 South-Western/Thomson LearningOur First Model: The Circular-Flow Diagram•Firms• Produce and sell goods and services• Hire and use factors of production•Households• Buy and consume goods and services• Own and sell factors of productionCopyright © 2004 South-Western/Thomson LearningOur First Model: The Circular-Flow Diagram•Markets for Goods and Services• Firms sell• Households buy•Markets for Factors of Production• Households sell• Firms buyCopyright © 2004 South-Western/Thomson LearningOur First Model: The Circular-Flow Diagram•Factors of Production• Inputs used to produce goods and services• Land, labor, and capitalCopyright © 2004 South-Western/Thomson LearningOur Second Model: The Production Possibilities Frontier•The production possibilities frontier is a graph that shows the combinations of output that the economy can possibly produce given the available factors of production and the available production technology.Figure 2 The Production Possibilities FrontierCopyright©2003 Southwestern/Thomson LearningProductionpossibilitiesfrontierABCQuantity ofCars Produced2,2006001,00030007002,0003,0001,000Quantity ofComputersProducedDCopyright © 2004 South-Western/Thomson LearningOur Second Model: The Production Possibilities Frontier•Concepts Illustrated by the Production Possibilities Frontier •Efficiency•Tradeoffs•Opportunity Cost•Economic GrowthFigure 3 A Shift in the Production Possibilities FrontierCopyright © 2004 South-WesternEQuantity ofCars Produced2,0007002,10075004,0003,0001,000Quantity ofComputersProducedACopyright © 2004 South-Western/Thomson LearningMicroeconomics and Macroeconomics•Microeconomics focuses on the individual parts of the economy.•How households and firms make decisions and how they interact in specific markets•Macroeconomics looks at the economy as a whole.•Economy-wide phenomena, including inflation, unemployment, and economic growthCopyright © 2004 South-Western/Thomson LearningTHE ECONOMIST AS POLICY ADVISOR•When economists are trying to explain the world, they are scientists.•When economists are trying to change the world, they are policy advisor.Copyright © 2004 South-Western/Thomson LearningPOSITIVE VERSUS NORMATIVE ANALYSIS•Positive statements are statements that attempt to describe the world as it is.•Called descriptive analysis•Normative statements are statements about how the world should be.•Called prescriptive analysisCopyright © 2004 South-Western/Thomson Learning•Positive or Normative Statements? •An increase in the minimum wage will cause a decrease in employment among the least-skilled.POSITIVE•Higher federal budget deficits will cause interest rates to increase.POSITIVE??POSITIVE VERSUS NORMATIVE ANALYSIS?Copyright © 2004 South-Western/Thomson Learning•Positive or Normative Statements? •The income gains from a higher minimum wage are worth more than any slight reductions in employment.NORMATIVE•State governments should be allowed to collect from tobacco companies the costs of treating smoking-related illnesses among the poor.NORMATIVE??POSITIVE VERSUS NORMATIVE ANALYSIS?Copyright © 2004 South-Western/Thomson LearningEconomists in Washington•. . . serve as advisers in the policymaking process of the three branches of government:•Legislative•Executive•JudicialCopyright © 2004 South-Western/Thomson LearningEconomists in Washington•Some government agencies that collect economic data and make economic policy:•Department of Commerce•merce.gov•Bureau of Labor Statistics•http://www.bls.gov•Congressional Budget Office•http://www.cbo.gov•Federal Reserve Board•http://www.federalreserve.govCopyright © 2004 South-Western/Thomson LearningWHY ECONOMISTS DISAGREE•They may disagree about the validity of alternative positive theories about how the world works.•They may have different values and, therefore, different normative views about what policy should try to accomplish. Table 2 Ten Propositions about Which Most Economists AgreeCopyright © 2004 South-WesternCopyright © 2004 South-Western/Thomson Learning美国和日本工人每人每年可以生产4辆汽车。

一个美国工人1年可以生产10吨粮食，而一个日本工人1年可以生产5吨粮食假设每个国家有1亿工人，他们能以不变的比例在一种物品与另一种物品之间进行转换1、画出日本和美国的生产可能性边界2、美国和日本生产一辆汽车的机会成本分别是多少?粮食呢？3、没有贸易时，每个国家有一半工人生产汽车，一半工人生产粮食每个国家能生产和消费多少汽车和粮食？4、若美国专门生产粮食，日本专门生产汽车，并且日本以1亿辆车交换2亿吨粮食，两国各生产和消费多少汽车和粮食？练习练习Copyright © 2004 South-Western/Thomson LearningInterdependence and the Gains from Trade•How do we satisfy our wants and needs in a global economy? •We can be economically self-sufficient.•We can specialize and tradewith others, leading to economic interdependence.Copyright © 2004 South-Western/Thomson LearningInterdependence and the Gains from Trade•Individuals and nations rely on specialized production and exchange as a way to address problems caused by scarcity. •But this gives rise to two questions:•Why is interdependence the norm?•What determines production and trade?Copyright © 2004 South-Western/Thomson LearningInterdependence and the Gains from Trade•Why is interdependence the norm?• Interdependence occurs because people are better off when they specialize and trade with others. •What determines the pattern of production and trade? •Patterns of production and trade are based upon differences in opportunity costs.Copyright © 2004 South-Western/Thomson LearningA PARABLE FOR THE MODERN ECONOMY•Imagine . . .•only two goods: potatoes and meat•only two people: a potato farmer and a cattle rancher•What should each produce?•Why should they trade?Copyright © 2004 South-Western/Thomson LearningTable 1 The Production Opportunities of the Farmer and RancherCopyright © 2004 South-WesternCopyright © 2004 South-Western/Thomson LearningProduction Possibilities•Self-Sufficiency •By ignoring each other:•Each consumes what they each produce.•The production possibilities frontier is also the consumption possibilities frontier.•Without trade, economic gains are diminished.Copyright © 2004 South-Western/Thomson LearningFigure 1 The Production Possibilities CurvePotatoes (ounces)416832A0Meat (ounces)(a) The Farmer ’s Production Possibilities FrontierIf there is no trade, the farmer chooses this production and consumption.Copyright©2003 Southwestern/Thomson LearningCopyright © 2004 South-Western/Thomson LearningFigure 1 The Production Possibilities CurveCopyright©2003 Southwestern/Thomson LearningPotatoes (ounces)1224B0Meat (ounces)(b) The Rancher ’s Production Possibilities Frontier4824If there is no trade, the rancher chooses this production and consumption.Copyright © 2004 South-Western/Thomson LearningThe farmer should produce potatoes. The rancher should produce meat.Specialization and Trade•The Farmer and the Rancher Specialize and Trade• Each would be better off if they specialized in producing the product they are more suited to produce, and then trade with each other.Copyright © 2004 South-Western/Thomson LearningTable 2 The Gains from Trade: A SummaryCopyright © 2004 South-WesternCopyright © 2004 South-Western/Thomson LearningFigure 2 How Trade Expands the Set of Consumption OpportunitiesCopyright©2003 Southwestern/Thomson LearningPotatoes (ounces)416517832AA*0Meat (ounces)(a) The Farmer’s Production and ConsumptionFarmer's production and consumption without tradeFarmer's consumption with tradeFarmer's production with tradeCopyright © 2004 South-Western/Thomson LearningFigure 2 How Trade Expands the Set of Consumption OpportunitiesCopyright © 2004 South-WesternPotatoes (ounces)12241327B0Meat (ounces)(b) The Rancher’s Production and Consumption48241218B*Rancher's consumption with tradeRancher's production with tradeRancher's production and consumption without tradeCopyright © 2004 South-Western/Thomson LearningTable 2 The Gains from Trade: A SummaryCopyright © 2004 South-WesternCopyright © 2004 South-Western/Thomson LearningWho can produce potatoes at a lower cost--the farmer or the rancher?THE PRINCIPLE OF COMPARATIVE ADVANTAGE•Differences in the costs of production determine the following:•Who should produce what?•How much should be traded for each product?Copyright © 2004 South-Western/Thomson LearningTHE PRINCIPLE OF COMPARATIVE ADVANTAGE •Differences in Costs of Production•Two ways to measure differences in costs of production:•The number of hours required to produce a unit of output (for example, one pound of potatoes).•The opportunity cost of sacrificing one good for another.Copyright © 2004 South-Western/Thomson LearningAbsolute Advantage•The comparison among producers of a good according to their productivity—absolute advantage•Describes the productivity of one person, firm, or nation compared to that of another.•The producer that requires a smaller quantity of inputs to produce a good is said to have an absolute advantage in producing that good.Copyright © 2004 South-Western/Thomson LearningThe Rancher has an absolute advantage in the production of both meat and potatoes.Absolute Advantage•The Rancher needs only 10 minutes to produce an ounce of potatoes, whereas the Farmer needs 15 minutes.•The Rancher needs only 20 minutes to produce an ounce of meat, whereas the Farmer needs 60 minutes.Copyright © 2004 South-Western/Thomson LearningOpportunity Cost and Comparative Advantage•Compares producers of a good according to their opportunity cost.•Whatever must be given up to obtain some item•The producer who has the smaller opportunity cost of producing a good is said to have a comparative advantage in producing that good.Copyright © 2004 South-Western/Thomson LearningComparative Advantage and Trade•Who has the absolute advantage?•The farmer or the rancher?•Who has the comparative advantage?•The farmer or the rancher?Copyright © 2004 South-Western/Thomson LearningTable 3 The Opportunity Cost of Meat and PotatoesCopyright © 2004 South-Western/Thomson LearningComparative Advantage and Trade•The Rancher’s opportunity cost of an ounce of potatoes is ¼ an ounce of meat, whereas the Farmer’s opportunity cost of an ounce of potatoes is ½ an ounce of meat.•The Rancher’s opportunity cost of a pound of meat is only 4 ounces of potatoes, while the Farmer’s opportunity cost of an ounce of meat is only 2 ounces of potatoes...Copyright © 2004 South-Western/Thomson Learning…so, the Rancher has a comparative advantage in the production of meat but the Farmer has a comparative advantage in the production of potatoes.Comparative Advantage and TradeCopyright © 2004 South-Western/Thomson LearningComparative Advantage and Trade•Comparative advantage and differences in opportunity costs are the basis for specialized production and trade.•Whenever potential trading parties have differences in opportunity costs, they can each benefit from trade.Copyright © 2004 South-Western/Thomson LearningComparative Advantage and Trade•Benefits of Trade •Trade can benefit everyone in a society because it allows people to specialize in activities in which they have a comparative advantage.Copyright © 2004 South-Western/Thomson LearningFYI—The Legacy of Adam Smith and David Ricardo•Adam Smith• In his 1776 book An Inquiry into the Nature and Causes of the Wealth of Nations, Adam Smith performed a detailed analysis of trade and economic interdependence, which economists still adhere to today.•David Ricardo•In his 1816 book Principles of Political Economy and Taxation, David Ricardo developed the principle of comparative advantage as we know it today.Copyright © 2004 South-Western/Thomson LearningAPPLICATIONS OF COMPARATIVE ADVANTAGE ???•Should Tiger Woods Mow His Own Lawn?Copyright © 2004 South-Western/Thomson LearningAPPLICATIONS OF COMPARATIVE ADVANTAGE •Should the United States Trade with Other Countries?•Each country has many citizens with different interests. International trade can make some individuals worse off, even as it makes the country as a whole better off. •Imports—goods produced abroad and sold domestically•Exports—goods produced domestically and sold abroadCopyright © 2004 South-Western/Thomson LearningSummary•Economists try to address their subjects with a scientist’s objectivity.•They make appropriate assumptions and build simplified models in order to understand the world around them.•Two simple economic models are the circular-flow diagram and the production possibilities frontier.Copyright © 2004 South-Western/Thomson LearningSummary•Economics is divided into two subfields:•Microeconomists study decisionmaking by households and firms in the marketplace.•Macroeconomists study the forces and trends that affect the economy as a wholeCopyright © 2004 South-Western/Thomson LearningSummary•A positive statement is an assertion about how the world is.•A normative statement is an assertion about how the world ought to be.•When economists make normative statements, they are acting more as policy advisors than scientists.Copyright © 2004 South-Western/Thomson LearningSummary•Economists who advise policymakers offer conflicting advice either because of differences in scientific judgments or because of differences in values.•At other times, economists are united in the advice they offer, but policymakers may choose to ignore it.Copyright © 2004 South-Western/Thomson LearningSummary•Each person consumes goods and services produced by many other people both in our country and around the world.•Interdependence and trade are desirable because they allow everyone to enjoy a greater quantity and variety of goods and services.Copyright © 2004 South-Western/Thomson LearningSummary•There are two ways to compare the ability of two people producing a good.•The person who can produce a good with a smaller quantity of inputs has an absolute advantage. •The person with a smaller opportunity cost has a comparative advantage.Copyright © 2004 South-Western/Thomson LearningSummary•The gains from trade are based on comparative advantage, not absolute advantage. •Trade makes everyone better off because it allows people to specialize in those activities in which they have a comparative advantage.•The principle of comparative advantage applies to countries as well as people.。