Comprehensive Study Notes: The Classical Full-Employment Model and Keynesian Critique

Context: Before delving into Keynesian macro-theory, it is essential to understand the classical theory of income and employment determination. This is particularly relevant for developing countries as it highlights factors governing their income and employment.
Keynes’s Definition: Keynes used the term "classical economists" to refer to all his predecessors, including Alfred Marshall and A.C. Pigou.
Governing Factors: According to Ricardo and Adam Smith, income and employment levels are governed by:
- Fixed capital stock.
- The wage-goods fund.
General Belief: The classical theory assumes a state of full employment or near-full employment in a free-market economy. There is an inherent tendency toward full-employment equilibrium because aggregate demand is always sufficient to purchase total output.
Foundational Notions: The model rests on two pillars:
1. Say’s Law of Markets.
2. Wage-Price Flexibility.

Definition: J.B. Say (a 19th-century French economist) stated: "Supply creates its own demand."
Mechanism: Every act of production generates income equal to the value of the goods produced. This income is spent by factors of production (labour, capital, land) to purchase those very goods.
Capital Accumulation: Any increase in production capacity or fixed capital stock automatically creates money income, expanding the market flow. This process continues until all resources are utilized.
Disregard for Overproduction: Because the source of demand is the income earned during production, classical economists rule out the possibility of general overproduction or a lack of aggregate demand.
Investment-Saving Equality:
- Income not spent on consumer goods is saved.
- Classical economists believed all savings are automatically spent on investment (capital) goods.
- The Interest Rate Mechanism: The rate of interest ( $i$ ) acts as an equilibrating force in the capital market. If savings increase, the rate of interest declines, incentivizing businessmen to increase investment expenditure until $I = S$ .

Self-Correcting Market: A free-market capitalist economy is viewed as a self-correcting organism. If aggregate demand falls, the economy does not shift to a lower output level; instead, prices and wages adjust.
Price Adjustment: If demand for goods declines, competition among sellers causes product prices ( $P$ ) to fall quickly. This restores balance between demand and supply at the full-employment level.
Wage Adjustment:
- If demand for output falls, the demand for labour ( $N$ ) also declines.
- Excess supply of labour prompts money wages ( $W$ ) to fall.
- A reduction in wages makes it profitable for firms to re-employ workers, restoring equilibrium at full employment.
Voluntary vs. Involuntary Unemployment: Classical economists deny the possibility of involuntary unemployment. Those not working at the market-determined wage are considered "voluntarily unemployed."
The Pigou Effect (Real Balance Effect): A.C. Pigou argued that an all-round cut in wages causes the price level to fall. This increases the real value of money assets (cash, bank deposits), making households feel wealthier. This "real balance effect" stimulates consumption demand, preventing a collapse in aggregate demand.

Short-Run Assumptions: The stock of fixed capital ( $K$ ) and technology ( $T$ ) are assumed constant.
Function: $Y = F(N, K, T)$
Relationship: Output ( $Y$ ) or real income increases only when the employment of labour ( $N$ ) increases.
Law of Diminishing Returns: As more labour is employed with a fixed capital stock, the marginal product of labour ( $MP_N$ ) diminishes.

Demand for Labour ( $Nd$ ): Derived from the marginal product of labour ( $MPN$ ). Profit-maximizing firms employ labour until the real wage ( $\frac{W}{P}$ ) equals the marginal product of labour:
- $\frac{W}{P} = MP_N$
- The demand function is $N_d = f(\frac{W}{P})$ , and it is downward-sloping.
Supply of Labour ( $N_s$ ): Depends on household preferences between income and leisure. Real wage ( $\frac{W}{P}$ ) is the opportunity cost of leisure.
- Substitution Effect: Higher real wages induce more work as leisure becomes more expensive.
- Income Effect: Higher real wages make people richer, inducing more leisure.
- Condition: Classicals believe the substitution effect is larger, making the supply curve upward-sloping: $N_s = g(\frac{W}{P})$ .
Equilibrium: Established where $Nd = Ns$ . This determines the equilibrium real wage ( $\frac{W}{P}0$ ) and the full-employment level ( $NF$ ).

Quantity Theory of Money: Based on Fisher’s Equation of Exchange: $MV = PY$ , or $P = \frac{MV}{Y}$ .
Variables:
- $M$ : Quantity of money.
- $V$ : Velocity of circulation.
- $Y$ : Level of aggregate output (constant at $Y_F$ in short run).
- $P$ : Price level.
Neutrality of Money: Since $Y$ and $V$ are constant, changes in money supply ( $M$ ) only affect nominal variables (prices and money wages). Real variables ( $Y, N, \frac{W}{P}, r$ ) remain unaffected. This independence is known as the Classical Dichotomy.
Classical Aggregate Supply Curve: A vertical straight line at the potential GDP/full-employment level ( $Y_F$ ). It is determined by supply-side real factors (labour, capital, technology) and is independent of price and demand.

Rejection of Say’s Law: Keynes argued that savers and investors are different groups with different motives. There is no guarantee that planned investment will always equal planned saving at full employment. Leakage through saving can lead to a deficiency of aggregate demand.
Fallacy of Wage Cuts: Keynes challenged Pigou’s wage-cut proposal. While a wage cut in one firm reduces costs, a general economy-wide wage cut reduces the purchasing power of the working class, further depressing aggregate demand and worsening unemployment.
Downward Wage Rigidity: Keynes observed that money wages are "sticky" or inflexible downward due to trade unions, long-term contracts, and "money illusion" (workers resist nominal wage cuts even if real wages fall due to price increases).
Unemployment Equilibrium: Keynes proved that an economy can reach equilibrium at less than full employment (Under-employment Equilibrium) due to a deficiency in effective demand. Government intervention via fiscal and monetary policy is necessary to restore full employment.

Technological Change: New technology increases marginal productivity, shifting the labour demand curve right and the production function upward, leading to higher real wages and potential GDP.
Labour Supply Increase: An increase in the labour force (e.g., through immigration or population growth) shifts the labour supply curve right, leading to lower real wages but a higher level of employment and potential GDP.
Capital Market Impact: Increased output from a larger labour force leads to increased savings, shifting the saving curve right and lowering the real rate of interest, which in turn stimulates investment.