BBS 2nd Year Economics

Chapter 4

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Chapter: Keynesian Theory of Employment

1. Introduction

The Keynesian theory of employment was developed by J.M. Keynes in 1936 in his famous book The General Theory of Employment, Interest and Money. Before Keynes, classical economists believed that unemployment was temporary and that the economy naturally moved towards full employment. Keynes rejected this view and argued that unemployment is caused by deficiency of aggregate demand. According to him, an economy can remain in underemployment equilibrium for a long period.

Keynesian theory is also known as the Demand Deficiency Theory of Employment.

2. Principle of Effective Demand

The foundation of Keynesian employment theory is the principle of effective demand. Effective demand is the level of aggregate demand at which aggregate demand equals aggregate supply. It represents demand backed by purchasing power.

Employment depends upon effective demand for consumption and investment goods. When effective demand decreases, output and employment also decrease.

3. Determinants of Effective Demand

1. Aggregate Demand Function (ADF)

Aggregate demand function shows the relationship between employment and expected income from the sale of output. The expected proceeds are known as Aggregate Demand Price (ADP). As employment increases, output and expected income also increase.

2. Aggregate Supply Function (ASF)

Aggregate supply function represents the minimum income that entrepreneurs must receive to employ a certain number of workers. It shows the supply price corresponding to different levels of employment.

4. Determination of Equilibrium Employment

Equilibrium level of employment is determined at the point where Aggregate Demand Function equals Aggregate Supply Function (ADF = ASF). According to Keynes, this equilibrium may occur at less than full employment.

5. Criticisms of Keynesian Theory

  • It is not a complete theory of employment.
  • It is based on short-run analysis.
  • It assumes a closed economy.
  • It ignores microeconomic foundations.
  • It is less applicable to developing countries.

6. Consumption Function

Consumption function refers to the functional relationship between income and consumption. It shows how consumption expenditure changes with change in income. There is a positive relationship between income and consumption.

Short-run Consumption Function:
C = a + bY
Long-run Consumption Function:
C = bY

7. Propensity to Consume

1. Average Propensity to Consume (APC)

APC = C / Y

It is the ratio of total consumption to total income.

2. Marginal Propensity to Consume (MPC)

MPC = ΔC / ΔY

It measures the change in consumption due to change in income.

8. Psychological Law of Consumption

According to Keynes, when income increases, consumption also increases but not by the same proportion because part of the income is saved.

9. Saving

Saving is the portion of income not spent on consumption.

S = Y - C
Saving Function: S = f(Y)

Average Propensity to Save (APS)

APS = S / Y

Marginal Propensity to Save (MPS)

MPS = ΔS / ΔY

10. Paradox of Thrift

Excessive saving reduces consumption and aggregate demand, which leads to decline in income, output, employment, and ultimately saving itself. Thus, thrift may result in poverty instead of wealth.

11. Investment

Investment refers to the addition to capital stock during a period.

Types of Investment

  • Gross and Net Investment
  • Induced and Autonomous Investment
  • Ex-ante and Ex-post Investment
  • Private and Public Investment

12. Marginal Efficiency of Capital (MEC)

MEC is the expected rate of return over cost from a capital asset. Investment decision depends upon comparison between MEC and market rate of interest.

If MEC > Interest Rate → Invest
If MEC = Interest Rate → Indifferent
If MEC < Interest Rate → Do not Invest

13. Income Determination in Two-Sector Economy

In a two-sector economy (Household + Firm):

Y = C + I
Equilibrium Condition: S = I

14. Concept of Multiplier

Multiplier shows the multiple effect of an initial change in investment on national income.

K = 1 / (1 - MPC) = 1 / MPS

Higher MPC leads to larger multiplier.

15. Leakages of Multiplier

  • Saving
  • Imports
  • Taxation
  • Hoarding
  • Debt repayment
  • Inflation

16. Three-Sector Economy

Includes Household, Business, and Government sectors. It is a closed economy without foreign trade.

17. Four-Sector Economy

Includes Household, Business, Government, and Foreign sectors. It is an open economy with exports and imports.

18. Fiscal Multipliers

Government Expenditure Multiplier

Gm = ΔY / ΔG

Tax Multiplier

Tm = ΔY / ΔT

Foreign Trade Multiplier

It shows the effect of change in exports and imports on national income.

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