1
垄断
Monopoly
第15章
Chapter 15
2
垄断
Monopoly
竞争企业是价格接受者，而垄
断企业是价格制定者。
While a competitive firm is a
price taker, a monopoly firm is
a price maker.
3
垄断
Monopoly
?一个企业被认为是垄断，如果
A firm is considered a monopoly if
…它是其产品的唯一的卖者。
it is the sole seller of its product.
…而且其产品没有相近的替代品。
its product does not have close
substitutes.
4
为什么会产生垄断
Why Monopolies Arise
产生垄断的根本原因是进入障碍。
The fundamental cause of
monopoly is barriers to entry.
5
为什么会产生垄断
Why Monopolies Arise
进入障碍有三个主要来源：
Barriers to entry have three sources:
?关键资源由一家企业所有。
Ownership of a key resource.
?政府给予一个企业生产某种产品的独享的权利。
The government gives a single firm the exclusive right to
produce some good.
?生产成本使一个生产者比大量生产者更有效率。
Costs of production make a single producer more efficient than
a large number of producers.
6
政府创造的垄断
Government-Created Monopolies
当政府给予一个企业在一些市场上出售某种物品的专
门权利时，就限制了进入。
Governments may restrict entry by giving a single firm
the exclusive right to sell a particular good in certain
markets.
2
7
政府创造的垄断
Government-Created Monopolies
专利和版权法是政府如何为公共利益创造
垄断的两个重要例子。
Patent and copyright laws are two
important examples of how government
creates a monopoly to serve the public
interest.
8
垄断资源
Monopoly Resources
虽然关键资源的独享所有权是产生垄断的潜在原
因，但实际上垄断很少产生于这种原因。
Although exclusive ownership of a key resource is a
potential source of monopoly, in practice
monopolies rarely arise for this reason.
9
自然垄断
Natural Monopolies
当一个企业能以低于两个或更多企业的成本为整
个市场供给一种物品时，这个行业是自然垄断。
An industry is a natural monopoly when a single
firm can supply a good or service to an entire
market at a smaller cost than could two or more
firms.
10
自然垄断
Natural Monopolies
当相关生产范围存在规模经济时，自然垄断就产生了
A natural monopoly arises when there are economies
of scale over the relevant range of output.
在任何一种既定的产量时，企业数量越多，每个企业的产
量越少，平均总成本越高。
For any given amount of output, a larger number of firms
leads to less output per firm and higher average total cost.
11
作为垄断原因的规模经济
Economies of Scale as a Cause of
Monopoly...
平均总成本
Average
total cost
产量Quantity of Output
成本
Cost
0
12
自然垄断
Natural Monopolies
?正常情况下，垄断利润吸引了进入者进入该市
场。
Normally, the monopolist’s profit attracts
entrants into the market.
?与此相反，进入另一个企业拥有自然垄断的市
场却没有吸引力。
By contrast, entering a market in which
another firm has a natural monopoly is
unattractive.
3
13
垄断与竞争
Monopoly versus Competition
说明竞争企业与垄断者之间差别的一个方法
，是考虑每个企业面对的需求曲线。
One Way to view the difference between a
competitive firm and a monopoly is to
consider the demand curve that each firm
faces.
14
垄断与竞争
Monopoly versus Competition
垄断Monopoly
?是唯一的生产者
Is the sole producer
?面临一条向右下方倾斜的需求曲线
Has a downward-sloping demand curve
?是价格制定者
Is a price maker
?降低价格以增加销售
Reduces price to increase sales
15
竞争与垄断
Competition versus Monopoly
竞争企业Competitive Firm
?是许多生产者之一
Is one of many producers
?面临一条水平的需求曲线
Has a horizontal demand curve
?是价格接受者
Is a price taker
?在同一价格上想卖多少就卖多少
Sells as much or as little at same price
16
产量
Quantity of
Output
需求
Demand
(a)竞争企业的需求曲线
A Competitive Firm’s
Demand Curve
(b) 垄断企业的需求曲线
A Monopolist’s
Demand Curve
0
价格
Price
0产量
Quantity of
Output
价格Price
需求Demand
竞争与垄断企业的需求曲线
Demand Curves for Competitive and
Monopoly Firms...
垄断者的收益
A Monopoly’s Revenue
?总收益Total Revenue
TR = P x Q
?平均收益Average Revenue
AR = TR/Q = P
?边际收益Marginal Revenue
MR = ?TR/?Q
18
垄断者的总收益、平均收益和边际收益
A Monopoly’s Total, Average, and
Marginal Revenue
数量
Quantity
(Q)
价格
Price
(P)
总收益
Total Revenue
(TR=PxQ)
平均收益
Average Revenue
(AR=TR/Q)
边际收益
Marginal Revenue
(MR= ?TR/?Q )
0 $11.00 $0.00
1 $10.00 $10.00 $10.00 $10.00
2 $9.00 $18.00 $9.00 $8.00
3 $8.00 $24.00 $8.00 $6.00
4 $7.00 $28.00 $7.00 $4.00
5 $6.00 $30.00 $6.00 $2.00
6 $5.00 $30.00 $5.00 $0.00
7 $4.00 $28.00 $4.00 -$2.00
8 $3.00 $24.00 $3.00 -$4.00
4
19
垄断者的边际收益
A Monopoly’s Marginal Revenue
垄断者的边际收益总是小于其物品的价格。
A monopolist’s marginal revenue is always less than the
price of its good.
?需求曲线是向右下方倾斜的。
The demand curve is downward sloping.
?当垄断者增加出售一个单位的物品，价格下降，从以
往所销售的各单位中获得的收益也下降。
When a monopoly drops the price to sell one more unit,
the revenue received from previously sold units also
decreases.
20
垄断者的边际收益
A Monopoly’s Marginal Revenue
当垄断者增加它的销售数量时，这对总收益(P x
Q)有两种效应：
When a monopoly increases the amount it sells, it
has two effects on total revenue (P x Q).
?产量效应：销售的产量越多，因此Q越大。
The output effect—more output is sold, so Q
is higher.
?价格效应：价格下降，因此P降低。
The price effect—price falls, so P is lower.
垄断者的需求和边际收益曲线
Demand and Marginal Revenue Curves
for a Monopoly...
数量
Quantity of Water
价格Price
$11
10
9
8
7
6
5
4
3
2
1
0
-1
-2
-3
-4
12345 678
边际收益
Marginal revenue
需求Demand
(平均收益
average revenue)
22
垄断者的利润最大化
Profit Maximization of a Monopoly
?使垄断者的利润最大化的产量是边际收益等于
边际成本时的产量。
A monopoly maximizes profit by producing
the quantity at which marginal revenue equals
marginal cost.
?然后垄断者用需求曲线找出使消费者购买那些
数量的价格。
It then uses the demand curve to find the price
that will induce consumers to buy that
quantity.
垄断者的利润最大化
Profit-Maximization for a Monopoly...
QuantityQ
MAX
0
Costs and
Revenue
需求Demand
平均总成本
Average total cost
边际收益Marginal revenue
Marginal
cost
A
1. 边际收益曲线与边际成本边际收益曲线与边际成本
曲线相交，决定了利润最大曲线相交，决定了利润最大
化的产量化的产量
The intersection of the
marginal-revenue curve re e c rve
and the marginal-cost
curve determines the
profit-maximizing
quantity...
B
2. 这时需求曲线表示出与这这时需求曲线表示出与这
种数量相一致的价格种数量相一致的价格
...and then the demand
curve shows the price
consistent with this
quantity.
垄断价格垄断价格
Monopoly
Price
边际成本
24
比较垄断和竞争
Comparing Monopoly and
Competition
?对于竞争企业来说，价格等于边际成本。
For a competitive firm, price equals
marginal cost.
P = MR = MC
?对于垄断企业来说，价格大于边际成本。
For a monopoly firm, price exceeds
marginal cost.
P > MR = MC
5
25
垄断的利润
A Monopoly’s Profit
利润等于总收益减总成本
Profit equals total revenue minus total costs.
利润Profit = TR - TC
利润Profit = (TR/Q - TC/Q) x Q
利润Profit = (P - ATC) x Q
垄
断
利
润
M
o
n
o
p
o
l
y
p
r
o
f
i
t
垄断的利润
The Monopolist’s Profit...
Quantity0
Costs and
Revenue
需求Demand
边际成本Marginal cost
边际收益Marginal revenue
Q
MAX
BMonopoly
Price
垄断价格
E
Average
total cost
平均总成本
D
平均总成本
Average total cost
C
成本和收益
27
垄断的利润
The Monopolist’s Profit
垄断者将获得经济利润，只要价格
高于平均总成本。
The monopolist will receive
economic profits as long as price is
greater than average total cost.
28
药品市场
The Market for Drugs...
成本和收益
Costs and
Revenue
专利期内的
价格Price
during
patent life
专利到期后
的价格
Price after
patent
expires
垄断数量
Monopoly
quantity
竞争数量
Competitive
quantity
0
数量
Quantity
需求
Demand
边际成本
Marginal
cost边际收益
Marginal
revenue
29
垄断的福利代价
The Welfare Cost of Monopoly
?与竞争企业不同，垄断企业收取的价格高于边际成
本。
In contrast to a competitive firm, the monopoly
charges a price above the marginal cost.
?从消费者角度看，这种高价格使垄断是不合意的。
From the standpoint of consumers, this high price
makes monopoly undesirable.
?但是，从企业所有者的角度看，高价格使垄断极为
合意。
However, from the standpoint of the owners of the
firm, the high price makes monopoly very desirable.
30
Price
0 Quantity
边际成本Marginal cost
需求Demand
(value to buyers)
效率产量
Efficient
quantity
垄断者的成本
Cost to
monopolist
对买者的
价值
Value to
buyers
对买者的
价值
Value to
buyers
垄断者的成本
Cost to
monopolist
对买者的价值大于卖者的成本
Value to buyers is greater
than cost to seller.
对买者的价值小于卖者的成本
Value to buyers is less than
cost to seller.
有效率的产量水平
The Efficient Level of Output...
6
31
无谓损失
The Deadweight Loss
由于垄断者收取高于边际成本的价格，它就在
消费者的支付意愿和生产者的成本之间打入了
一个楔子。
Because a monopoly sets its price above marginal
cost, it places a wedge between the consumer’s
willingness to pay and the producer’s cost.
?这个楔子导致销售量小于社会最优量。
This wedge causes the quantity sold to fall
short of the social optimum.
垄断的无效率
The Inefficiency of Monopoly...
Quantity0
需求Demand
边际收益
Marginal
Revenue
边际成本Marginal cost
垄断价格
Monopoly cost
无谓损失
Deadweight
loss
效率数量
Efficient
quantity
垄断数量
Monopoly
quantity
Price
33
垄断的无效率
The Inefficiency of Monopoly
垄断者生产的产量小于社会有
效率的产量。
The monopolist produces less
than the socially efficient
quantity of output.
34
无谓损失
The Deadweight Loss
?垄断引起的无谓损失类似于税收引起的无谓损失。
The deadweight loss caused by a monopoly is similar
to the deadweight loss caused by a tax.
?这两种情况之间的差别是政府得到了税收的收入，
而私人企业得到了垄断利润。
The difference between the two cases is that the
government gets the revenue from a tax, whereas a
private firm gets the monopoly profit.
35
对垄断的公共政策
Public Policy Toward Monopolies
政府以四种方式中的一种对垄断问题作出反应：
Government responds to the problem of
monopoly in one of four ways.
?努力使垄断行业更有竞争性。
Making monopolized industries more competitive.
?管制垄断者的行为。
Regulating the behavior of monopolies.
?把一些私人垄断变为公有企业。
Turning some private monopolies into public enterprises.
?什么也不做。
Doing nothing at all.
36
用反托拉斯法增强竞争
Increasing Competition with
Antitrust Laws
?反托拉斯法是一系列目的在于遏制垄断权力的法律的集合。
Antitrust laws are a collection of statutes aimed at curbing
monopoly power.
?反托拉斯法给予政府促进竞争的各种方法。
Antitrust laws give government various ways to promote
competition.
?它们允许政府阻止企业合并。
They allow government to prevent mergers.
?它们允许政府分解公司。
They allow government to break up companies.
?它们禁止公司从事使市场竞争削弱的活动。
They prevent companies from performing activities which
make markets less competitive.
7
37
美国的两个重要的反托拉斯法
Two Important Antitrust Laws
? 1890年的Sherman反托拉斯法（Sherman
Antitrust Act）
?减少当时强大的“托拉斯”市场势力。
Reduced the market power of the large and powerful
“trusts” of that time period.
? 1914年的Clayton法（Clayton Act）
?加强政府的权力，并使私人对此类诉讼合法化。
Strengthened the government’s powers and
authorized private lawsuits.
38
管制
Regulation
政府管制垄断者收取的价格。
Government may regulate the prices
that the monopoly charges.
?如果价格定在等于边际成本，资源
配置就将是有效率的。
The allocation of resources will be
efficient if price is set to equal
marginal cost.
39
自然垄断的边际成本定价
Marginal-Cost Pricing for a Natural
Monopoly...
Regulated price
受管制的价格
Quantity0
亏损Loss
Price
需求Demand
边际成本Marginal cost
平均总成本
Average total cost
Average total cost
平均总成本
40
管制
Regulation
在实际中，管制者允许垄断者从降低成
本中以更高利润形式保留一些利益，这
种做法要求对边际成本定价的某种偏离
In practice, regulators will allow
monopolists to keep some of the benefits
from lower costs in the form of higher
profit, a practice that requires some
departure from marginal-cost pricing.
41
公有制
Public Ownership
政府不是管制由私人经营的自然垄断
，而是由自己经营自然垄断本身（比
如，在美国，政府经营美国邮政局）
Rather than regulating a natural
monopoly that is run by a private firm,
the government can run the monopoly
itself. (e.g. in the U.S., the government
runs the Postal Service).
42
什么也不做
Doing Nothing
如果相对于公共政策的不完善性
而言市场失灵的程度肯定较小，
那末政府可以什么也不做。
Government can do nothing at all
if the market failure is deemed
small compared to the
imperfections of public policies.
8
43
价格歧视
Price Discrimination
企业试图将同样的产品以不同的价格卖给
不同的顾客。这一做法就是价格歧视。
Firms try to sell the same good to different
customers for different prices. This practice
is called price discrimination.
44
价格歧视
Price Discrimination
当一种物品在竞争市场出售时，价格歧视是不可
能的，因为有许多以市场价格出售同一种物品的
企业。企业能够实行价格歧视，它一定具有某种
市场势力。
Price discrimination is not possible when a good is
sold in a competitive market since there are many
firms all selling at the market price. In order to
price discriminate, the firm must have some
market power.
45
完全价格歧视
Perfect Price Discrimination
完全价格歧视是指这种情况：垄断者
完全了解每个顾客的支付意愿，并对
每位顾客收取不同的价格。
Perfect price discrimination refers to
the situation when the monopolist
knows exactly the willingness to pay of
each customer and can charge each
customer a different price.
46
价格歧视
Price Discrimination
?价格歧视的两个重要效应：
Two important effects of price
discrimination:
?它可以增加垄断者的利润。
It can increase the monopolist’s profits.
?它可以减少无谓损失。
It can reduce deadweight loss.
47
无谓损失Deadweight
loss
消费者剩余Consumer
surplus
没有价格歧视时的福利
Welfare Without Price Discrimination
Price
0Quantiy
利润Profit
需求Demand
边际成本Marginal cost
Marginal
revenue
销售量Quantity sold
Monopoly
price
(a)单一价格垄断者
Monopolist with Single Price
垄断价格
边际收益
48
利润
Profit
有价格歧视时的福利
Welfare With Price Discrimination
Price
0Quantiy
需求Demand
边际成本Marginal cost
Quantity sold
(b) 完全价格歧视垄断者
Monopolist with Perfect Price Discrimination
销售量
9
49
价格歧视的例子
Examples of Price Discrimination
?电影票Movie tickets
?机票价格Airline prices
?折扣劵Discount coupons
?奖学金Financial aid
?数量折扣Quantity discounts
50
垄断的普遍性
The Prevalence of Monopoly
?垄断问题有多普遍？
How prevalent are the problems of monopolies?
?一方面，垄断常见
Monopolies are common.
?多数企业对它们收取的价格都有某种控制，因为不同企业
的产品不完全一样。
Most firms have some control over their prices because of
differentiated products.
?另一方面，有相当大垄断势力的企业很少。
Firms with substantial monopoly power are rare.
?没有多少物品真正是独一无二的。
Few goods are truly unique.
51
总结
Summary
?垄断是在其市场上为唯一卖者的企业。
A monopoly is a firm that is the sole seller in its
market.
?它面临对其产品的向右下方倾斜的需求曲线。
It faces a downward-sloping demand curve for
its product.
?垄断者的边际收益总是低于其物品的价格。
A monopoly’s marginal revenue is always below
the price of its good.
52
总结
Summary
?正如竞争企业一样，垄断企业也通过生产边
际收益等于边际成本的产量来实现利润最大
化。
Like a competitive firm, a monopoly
maximizes profit by producing the quantity
at which marginal cost and marginal revenue
are equal.
?与竞争企业不同，垄断企业的价格高于它的
边际收益，所以它的价格高于边际成本。
Unlike a competitive firm, its price exceeds
its marginal revenue, so its price exceeds
marginal cost.
53
总结
Summary
?垄断者利润最大化的产量水平低于使消费者
与生产者剩余之和最大化的产量。
A monopolist’s profit-maximizing level of
output is below the level that maximizes the
sum of consumer and producer surplus.
?垄断引起的无谓损失类似于税收引起的无谓
损失。
A monopoly causes deadweight losses similar
to the deadweight losses caused by taxes.
54
总结
Summary
?政策制定者可以对垄断行为的无效率作出反
应，包括反托拉斯法、价格管制、或把垄断
企业改由政府经营。
Policymakers can respond to the inefficiencies
of monopoly behavior with antitrust laws,
regulation of prices, or by turning the
monopoly into a government-run enterprise.
?如果市场失灵肯定要小，政府可以决定什么
都不做。
If the market failure is deemed small,
policymakers may decide to do nothing at all.
10
55
总结
Summary
?垄断者可以通过根据买者的支付意愿对同
一种物品收取不同的价格来增加利润。
Monopolists can raise their profits by
charging different prices to different
buyers based on their willingness to pay.
?价格歧视可以提高经济福利和减少无谓损
失。
Price discrimination can raise economic
welfare and lessen deadweight losses.
