Inflation, Unemployment, and Phillips-Curve Trade-offs

A clear progression through the Phillips curve, inflation expectations, supply shocks, stagflation, and the short-run and long-run trade-offs of stabilization policy.

The Short-Run

The begins with a short-run relationship between inflation and unemployment. In its basic form, lower unemployment is associated with higher inflation, while higher unemployment is associated with lower inflation.

The relationship can be represented as:

\pi = \pi^e - \alpha(u-u_n)

Here, $\pi$ is actual inflation, $\pi^e$ is expected inflation, $u$ is actual unemployment, $u_n$ is the , and $\alpha$ measures how strongly inflation responds to unemployment conditions.

The intuition is that strong demand for labor makes firms compete for workers. Wages rise, and firms may raise prices to cover higher labor costs. In a weak economy, labor-market pressure and inflationary pressure are generally weaker.

Takeaway: The short-run describes a tendency, not a guaranteed mechanical relationship. Expectations and supply conditions also matter.

Demand Changes and Temporary Trade-offs

The short-run trade-off results from gradual adjustment in some wages, prices, and expectations. If government spending rises or interest rates fall, aggregate demand increases. Firms respond by expanding production and hiring more workers. Unemployment can fall while inflation rises, producing movement along a given short-run .

For example, suppose expected inflation is $2\%$ , the is $5\%$ , and actual unemployment is $4\%$ . Because unemployment is below the natural rate, labor markets are relatively tight. Wage demands and firms’ prices may rise, causing actual inflation to exceed expected inflation.

If unemployment instead rises to $7\%$ , wage and price pressures may weaken, and actual inflation may fall below expected inflation.

The reverse occurs after contractionary policy: lower aggregate demand can reduce inflation but increase unemployment in the short run.

Takeaway: Demand-side policy can temporarily exchange some unemployment for inflation, or some inflation for unemployment, but the trade-off is not necessarily permanent.

Expectations and Phillips-Curve Shifts

are central because workers and firms care about purchasing power and real costs, not only nominal wages and prices. If workers expect prices to rise by $4\%$ , they may seek wage increases of approximately $4\%$ simply to maintain purchasing power. Firms may then raise prices in response to higher labor costs and anticipated future costs.

When expected inflation rises, the short-run shifts upward:

\pi^e \uparrow \;\Rightarrow\; \text{higher inflation at every unemployment rate}

With adaptive expectations, recent inflation strongly influences beliefs about future inflation. With rational expectations, people use available information about economic conditions and policy. A credible commitment to price stability can help keep expectations stable; a loss of confidence can make inflation harder to reduce.

Distinguish a movement from a shift:

A change in aggregate demand moves the economy along a given short-run curve.
A change in expected inflation shifts the entire short-run curve.

Takeaway: Reducing inflation requires attention not only to current demand but also to whether wage setters and price setters expect inflation to continue.

The Long-Run

In the long run, the is vertical at the . A policy-induced increase in demand may initially lower unemployment below the natural rate and raise inflation. Over time, workers and firms recognize the higher inflation, revise expectations upward, and adjust nominal wages and prices. The temporary employment gain disappears, and unemployment returns toward its natural rate.

This is the principle: anticipated inflation can change nominal outcomes, such as the price level, but it does not permanently determine real unemployment or real GDP.

The adjustment can be summarized as follows:

Expansionary policy raises aggregate demand.
Output increases, unemployment falls, and inflation rises initially.
Expected inflation increases.
Nominal wages and prices adjust.
Unemployment returns toward the natural rate.

Trying to keep unemployment permanently below the natural rate would require increasingly higher and unexpected inflation. That strategy is not sustainable.

Takeaway: Policymakers can influence real activity temporarily, but they cannot permanently buy lower unemployment with higher anticipated inflation.

Supply Shocks and

A changes production costs or productive capacity rather than simply changing total demand. An adverse shock, such as a sharp increase in oil prices, can raise firms’ costs, reduce production and employment, and increase prices simultaneously.

The main cases are:

An expansionary demand shock increases inflation and decreases unemployment; this is movement up and left along the short-run curve.
A contractionary demand shock decreases inflation and increases unemployment; this is movement down and right along the short-run curve.
An adverse increases both inflation and unemployment; this shifts the short-run curve upward or to the right.
A favorable decreases both inflation and unemployment; this shifts the short-run curve downward or to the left.

When high or rising inflation occurs together with high unemployment and weak growth, the economy is experiencing . This outcome is especially difficult because demand-side policies work in opposite directions with respect to the two problems.

Takeaway: Always identify whether a change comes from aggregate demand, expected inflation, or production costs before deciding whether the economy moved along a curve or the curve shifted.

Stabilization Policy Trade-offs

Stabilization policy during involves a difficult choice. Expansionary monetary or fiscal policy can support output and reduce unemployment, but it may intensify inflation by adding demand while production costs are already high. Contractionary policy can reduce inflation, but it may further reduce output and increase unemployment in the short run.

Possible responses include:

Monetary restraint: Prevent a temporary price shock from becoming persistent inflation.
Credible inflation targets: Keep long-run anchored.
Targeted fiscal assistance: Help households most affected by higher prices without stimulating economy-wide demand excessively.
Supply-side measures: Remove production bottlenecks, improve transportation capacity, or increase energy supply.
Patience when appropriate: If the shock is temporary and expectations remain stable, avoid causing an unnecessary recession while the shock fades.

The appropriate response depends on whether the shock is temporary or persistent and whether remain anchored. A one-time increase in oil prices can raise the price level without creating permanently higher inflation; persistent inflation is more likely when wages, prices, and expectations continue adjusting upward.

Takeaway: Stabilization policy must balance price stability, employment, and economic growth rather than assuming that one demand-side instrument can improve every outcome at once.

The Short-Run Phillips Curve