25.2 The Building Blocks of Keynesian Analysis

Keynesian Theory and Aggregate Demand

Keynesian theory challenges the idea that markets always self-correct. During recessions, wages and prices don't adjust quickly enough to restore equilibrium, so downturns can drag on. The Keynesian solution: government intervention to boost aggregate demand and push the economy toward recovery.

This section covers three core building blocks of Keynesian analysis: why wages and prices are "sticky," how aggregate demand shifts affect the economy, and how the expenditure multiplier amplifies changes in spending.

Sticky Wages and Prices

Sticky wages and prices refer to the tendency of wages and prices to adjust slowly in response to economic changes, rather than moving freely to a new equilibrium.

Why do wages get stuck? A few reasons:

• Labor contracts lock in nominal wages for months or years, so even if demand drops, employers can't immediately cut pay
• Social norms and morale discourage wage cuts because workers view them as unfair, which can hurt productivity
• Minimum wage laws set a legal floor that prevents wages from falling below a certain point

Prices are sticky for similar reasons:

• Menu costs make it expensive to change prices frequently (think of reprinting catalogs, updating systems, renegotiating contracts)
• Long-term supply contracts fix input prices for extended periods
• Customer goodwill discourages frequent price hikes that might drive buyers away

Here's why stickiness matters so much in a recession. When aggregate demand falls, firms face lower demand for their products. But if they can't cut wages or prices fast enough, they can't reduce costs to match. Instead, they cut output and lay off workers. Those laid-off workers then spend less, which reduces aggregate demand even further. This creates a downward spiral that the market won't quickly fix on its own.

Keynesian theory argues that government intervention, through increased government spending or tax cuts, is necessary to break this cycle by directly boosting aggregate demand.

Aggregate Demand Shifts

Aggregate demand (AD) represents the total spending on goods and services in an economy at each price level. It has four components:

$AD = C + I + G + (X - M)$

• C = Consumption (household spending)
• I = Investment (business spending on capital)
• G = Government spending
• X - M = Net exports (exports minus imports)

The AD curve slopes downward: as the price level falls, the quantity of output demanded rises. What Keynesian analysis focuses on is what happens when the entire curve shifts.

A rightward shift (increase in AD) means more total spending at every price level. This leads to:

• Higher real GDP (more output)
• Increased employment as firms hire to meet stronger demand
• Potential inflationary pressure, especially if the economy is already near full capacity

A leftward shift (decrease in AD) means less total spending at every price level. This leads to:

• Lower real GDP
• Rising unemployment as firms cut workers
• Possible deflation or at least downward pressure on prices

In the Keynesian view, leftward AD shifts are particularly dangerous because sticky wages and prices prevent the economy from adjusting back to full employment on its own. That's the whole reason government action becomes necessary.

Expenditure Multiplier Effect

The expenditure multiplier captures a powerful idea: an initial change in spending doesn't just affect GDP once. It ripples through the economy, creating a total impact that's larger than the original spending change.

The formula for the simple expenditure multiplier is:

$\text{Multiplier} = \frac{1}{1 - MPC}$

where MPC (marginal propensity to consume) is the fraction of each additional dollar of income that gets spent rather than saved.

Here's how the multiplier works, step by step:

1. The government spends an additional $100 million on infrastructure
2. Construction workers and firms receive that $100 million as income
3. If the MPC is 0.8, they spend $80 million of it on goods and services
4. The recipients of that $80 million then spend $64 million (0.8 × $80M)
5. This chain continues, with each round of spending getting smaller

With an MPC of 0.8, the multiplier is $\frac{1}{1 - 0.8} = \frac{1}{0.2} = 5$. So that initial $100 million in government spending ultimately generates $500 million in total GDP.

The size of the multiplier depends entirely on the MPC:

• Higher MPC (e.g., 0.9) → larger multiplier (10), because people spend most of their additional income, keeping the chain going
• Lower MPC (e.g., 0.5) → smaller multiplier (2), because people save more at each round, and the spending chain dies out faster

Autonomous spending refers to spending that doesn't depend on the current level of income, such as government spending or business investment driven by expectations. Changes in autonomous spending are what trigger the multiplier process, which is why Keynesian economists pay close attention to shifts in government budgets and investment confidence as drivers of economic fluctuations.