Chapter 11
Classical and Keynesian Economics
Copyright 2002 by The McGrawHill Companies, Inc. All rights reserved.
111
Chapter Objectives
• Say’s law
• Classical equilibrium
• Real balance, interest rate, and foreign
exchange effects
• Aggregate demand
• Aggregate supply in the long run and
short run
Copyright 2002 by The McGrawHill Companies, Inc. All rights reserved.
112
Chapter Objectives
• The Keynesian critique of the classical
system
• Equilibrium at varying price levels
• Disequilibrium and equilibrium
• Keynesian policy prescriptions
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113
Part I: The Classical Economic
System
• The centerpiece of classical economics is
Say’s law
– Say’s law states, “Supply creates its own
demand”
– This means that somehow, what we produce
– supply – all gets sold
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114
Why Does Anybody Work?
• People work because they want money to buy
things
– People who produce things are paid. They spend
this money on what other people produce
– As long as everyone spends everything that he or she
earns, the economy is OK
• But, the economy begins to have problems when people
save part of their incomes
– People do save, and saving is crucial to economic
growth
• Without saving, we could not have investment – the
production of plant, equipment, and inventory
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115
Consumer Goods and Investment
Goods
• Think of production as consisting of two
products: consumer goods and invest
ment goods (for now, we’re ignoring
government goods)
• The money spent on consumer goods is
designated by the letter C
• The money spent on investment goods is
designated by the letter I
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116
Consumer Goods and
Investment Goods
If we think of GDP as total spending, then
GDP would be C + I
If we think of GDP as income received, then
GDP would be C + S
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117
Consumer Goods and
Investment Goods
(Continued)
If we think of GDP as total spending, then
GDP would be C + I
If we think of GDP as income received, then
GDP would be C + S
GDP = C + I
GDP = C + S
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118
Consumer Goods and
Investment Goods
(Continued)
GDP = C + I
GDP = C + S
And since things equal to the same thing are equal to
each other, we have
C + I = C + S
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119
Consumer Goods and
Investment Goods
(Continued)
GDP = C + I
GDP = C + S
Things equal to the same thing are equal to each other
C + I = C + S
Next, we can subtract the same thing from both sides
of the equation. In this case we subtract C
I = S
Copyright 2002 by The McGrawHill Companies, Inc. All rights reserved.
1110
Say’s Law Revisited
Households
Households
The economy produces a supply of
consumer goods and investment
goods (Aggregate Supply = AS)
7.0 AS
Firms
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1111
Say’s Law Revisited
S=0.5 They save the rest
Households
Households
AS=7.0
The people who produce
these goods (Households)
spend part of their incomes
on consumer goods
C=6.5
Firms
I=0.5
Their savings are
borrowed by investors
who spend this money on
investment goods
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Copyright 2002 by The McGrawHill Companies, Inc. All rights reserved.
Say’s Law Revisited
S=0.5
Households
Households
AS=7.0
GDP = C + I
GDP = 6.5 + 0.5
GDP = 7.0
C=6.5
I = S
Firms
I=0.5
GDP = 7.0 = Aggregate Demand (AD)
We can see that Say’s law holds up, at least in accordance with classical analysis.
Supply does create its own demand. Everything produced is sold. (AS = GDP=AD)
Copyright 2002 by The McGrawHill Companies, Inc. All rights reserved.
1113
Supply and Demand Revisited
The curves cross at a
price of $7.30 and a
quantity of 6
10
S
9
8
7
D
6
2
4
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6
8
Quantity
10
12
14
1114
Supply and Demand Revisited
The Loanable Funds Market
The demand and
supply curves cross at
an interest rate of 15
percent
Supply of
savings
20
15
10
5
Demand for
investment
funds
0
Quantity of loanable funds
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1115
Supply and Demand Revisited
If the quantity supplied is
greater than the quantity
demanded at a certain price
(in this case $8), the price
will fall to the equilibrium
level ($6), at which quantity
demanded is equal to
quantity supplied.
Market for Hypothetical Product
14
S
12
10
8
6
4
2
D
0
Quantity
Copyright 2002 by The McGrawHill Companies, Inc. All rights reserved.
1116
Supply and Demand Revisited
Hypothetical Labor Market
If the wage rate is set too high
($9 an hour),the quantity of
labor supplied exceeds the
quantity of labor demanded.
The wage rate falls to the
equilibrium level of $7; at
that wage rate, the quantity of
labor demanded equals the
quantity supplied
20
Supply of
labor
18
16
14
12
10
8
6
4
2
Demand
for labor
0
Quantity of labor
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1117
The Classical Equilibrium: Aggregate
Demand Equals Aggregate Supply
• On the micro level, when quantity demanded
equals quantity supplied, we’re at equilibrium
• On the macro level, when aggregate demand
equals aggregate supply, we’re at equilibrium
• The classical economist believed our economy
was either at, or tending toward , full
employment
• So at classical equilibrium – the GDP at which
aggregate demand was equal to aggregate
supply – we were at full employment
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1118
The Aggregate Demand Curve
Aggregate Demand Curve (in trillions of dollars)
The level of aggregate
demand varies inversely
with the price level. As
the price level declines,
people are willing to
purchase more and more
output. Alternatively, as
the price level rises, the
quantity of output
purchased goes down
180
160
140
120
100
80
60
Aggregate
demand
40
20
0
0
1
2
3
4
5
6
7
8
Real GDP (in trillions of dollars)
9
10
Aggregate demand is the total value of real GDP that all sectors of
the economy are willing to purchase at various price levels
1119
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The Aggregate Demand Curve
• There are three reasons why the quantity
of goods and services purchased declines
as the price level increases
– An increase in the price level reduces the
wealth of people holding money, making
them feel poorer and reducing their
purchases
• This is called the real balance effect
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1120
The Aggregate Demand Curve
• The higher price level pushes up the
interest rate, which leads to a reduction
in the purchase of interestsensitive
goods, such as cars and houses
– This is called the interest rate effect
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1121
The Aggregate Demand Curve
• Net exports decline as foreigners buy less
from us and we buy more from them at
the higher price level
– This is called the foreign purchases effect
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1122
The Real Balance Effect
• The real balance effect is the influence of
a change in your purchasing power on
the quantity of real GDP that you are
willing to buy
– A decrease in the price level increases the
quantity of real money
• The larger the quantity of real money, the larger
the quantity of goods and services demanded
– An increase in the price level decreases the
quantity of real money
• The smaller the quantity of real money, the
smaller the quantity of goods and services
demanded
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1123
The Interest Rate Effect
• A rising price level pushes up interest
rates, which in turn lower the
consumption of certain goods and
services and also lower investment in new
plant and equipment
– A rising price level pushes up interest rates
and lowers both consumption and
investment
– A declining price level pushes down interest
rates and encourages both consumption and
investment
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1124
The Foreign Purchases Effect
• When the price level in the United States rises
relative to the price levels in other countries
– American goods become more expensive relative to
foreign goods
• American imports rise (foreign goods are cheaper)
• American exports decline (American goods are more
expensive)
• Thus, American net exports (exports minus
imports) component of GDP declines
• When the price level declines, the net exports
component (and GDP) rises
Copyright 2002 by The McGrawHill Companies, Inc. All rights reserved.
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