01 什么是经济学

经济学是研究社会如何生产分配 产品以试图满足其成员需求的。

经济学的三类问题(从小到大,一二是微观经济学、三是宏观经济学):

  • How People Make Decisions

  • How People Interact

  • How the Economy as a Whole Works

1.1 经济学的十个原理

How People Make Decisions

1. People face tradeoffs.

  • To get one thing, we usually have to give up another thing.

2. The cost of something is what you give up to get it.

  • People decide whether to do one thing or not by considering its costs and benefits.

  • However, making decisions requires trading off this thing against other alternatives.

The opportunity cost of an item is what you give up to obtain that item.

3. Rational people think at the margin.

  • People make optional decisions by comparing costs and benefits at the margin.

Marginal changes are small, incremental adjustments to an existing plan of action.

4. People respond to incentives.

  • Marginal changes in costs or benefits motivate people to respond.

  • The decision to choose one alternative over another occurs when that alternative's marginal benefits exceed its marginal costs.

How People Interact

5. Trade can make everyone better off.

  • People gain from their ability to trade with one another.

  • Competition results in gains from trading.

  • Trade allows people to specialize in what they do best.

6. Markets are usually a good way to organize economic activity.

  • In a market economy, households decide what to buy and who to work for.

  • Firms decide who to hire and what to produce.

  • Adam Smith made the observation that households and firms interacting in markets act as if guided by an invisibale hand.(看不见的手实际上就是市场价格)

  • Because households and firms look at prices when deciding what to buy and sell, they unknowingly take into account the social benefits and costs of their actions.

  • As a result, prices guide decision makers to reach outcomes that tend to maximize the welfare of society as a whole.

7. Goverments can sometimes improve market outcomes.

改进两个地方:

  • 效率(市场失灵等)

  • 公平

Market failure occurs when the market fails to allocate resources efficiently.

市场失灵的两种原因:

  • 外部性

    • Markey failure may by caused by an externality, which is the impact of one person or firm's actions on the well-being of a bystander.(不是通过价格来影响)

  • 市场势力

    • Market failure may also be caused by market power, which is the ability of a single person or firm to unduly influence market prices.

How the Economy as a Whole Works

8. The standard of living depends on a country's production.

Standard of living may be measured in different ways:

  • By comparing personal incomes.

  • By comparing the total market value of a nation's production.

Almost all variations in living standards are explained by differences in countries' productivities.

Productivity is the amount of goods and services produced from each hour of a worker's time.(注意是用小时来衡量,因为有些国家假期多,工作时间短。所以用小时来度量)

9. Prices rise when the governmennt prints too much money.

Inflation is an increase in the overall level of prices in the economy.

  • One cause of inflation is the growth in the quantity of money.

10. Society faces a short-run tradeoff between inflation and unemployment.

The Phillips Curve illustrates the tradeoff between inflation and unemployment.

  • By changing the amount that the government spends, the amount it taxes, and the amount of money it prints, policy makers can, in the short run, influence the combination of inflation and unemployment that the economy experiences.