# Understanding the Phillips Curve: Inflation and Unemployment Dynamics

![Philips Curve](https://www.investopedia.com/thmb/N8aeS4t_B-Stk6TO2IavqV5Lddk=/1500x0/filters:no_upscale():max_bytes(150000):strip_icc()/Philips-Curve-V3-7eb591d5e5174452b921fd88677c1229.jpg)

*— Investopedia / Matthew Collins*

## What Is the Phillips Curve?

The Phillips curve suggests a stable, inverse relationship between inflation and unemployment, proposing that economic growth leads to inflation, which in turn reduces unemployment. This theory, introduced by economist William Phillips, was initially influential in shaping monetary policy. However, its validity faced challenges during the 1970s when stagflation—characterized by simultaneous high unemployment and inflation—emerged, sparking debate about its applicability in modern economic contexts.

Despite these challenges, the Phillips curve remains an important framework for understanding the interplay between inflation and unemployment in economic discussions.

### Key Takeaways

*   The Phillips curve suggests an inverse relationship between inflation and unemployment, meaning that as inflation rises, unemployment tends to decrease, and vice versa.
*   This theory faced criticism during the 1970s stagflation, which saw high inflation and high unemployment occurring simultaneously, challenging the assumed stable trade-off.
*   In the long run, the Phillips curve might shift vertically at the natural rate of unemployment (NAIRU), as workers' expectations of inflation adjust, neutralizing the curve's short-term trade-off.
*   Ongoing debates about the Phillips curve impact economic policies, as policymakers utilize it as a framework to balance inflation and unemployment rates.

## How the Phillips Curve Explains Inflation and Unemployment

The concept behind the Phillips curve states that the change in unemployment within an economy has a predictable effect on [price inflation](https://www.investopedia.com/terms/p/price_inflation.asp). The inverse relationship between unemployment and inflation is depicted as a downward-sloping, convex curve, with inflation on the Y-axis and unemployment on the X-axis. Increasing inflation decreases [unemployment](https://www.investopedia.com/terms/u/unemployment-insurance.asp), and vice versa. Alternatively, a focus on decreasing unemployment also increases inflation, and vice versa.

In the 1960s, it was believed that fiscal stimulus would boost [aggregate demand](https://www.investopedia.com/terms/a/aggregatedemand.asp), increase labor demand, reduce unemployment, and lead companies to raise wages to attract workers. The corporate cost of wages then increases, and companies pass these costs along to consumers in the form of price increases.

This belief led many governments to use a "stop-go" strategy, setting an inflation target and adjusting fiscal and monetary policies to meet it. However, the stable trade-off between inflation and unemployment broke down in the 1970s with the rise of stagflation, calling into question the validity of the Phillips curve.

## How Stagflation Challenged the Phillips Curve

Stagflation occurs when an economy experiences stagnant economic growth, high unemployment, and high price inflation. This scenario, of course, directly contradicts the theory behind the Phillips curve. The United States never experienced stagflation until the 1970s, when rising unemployment did not coincide with declining inflation. Between 1973 and 1975, the U.S. economy posted six consecutive quarters of declining GDP and at the same time tripled its inflation.

## The Role of Expectations in the Long-Run Phillips Curve

The phenomenon of stagflation and the breakdown in the Phillips curve led economists to look more deeply at the role of expectations in the relationship between unemployment and inflation. Because workers and consumers can [adapt their expectations](https://www.investopedia.com/behavioral-economics-4689799) about future inflation rates based on current rates of inflation and unemployment, the inverse relationship between inflation and unemployment could only hold over the short-run.

When the central bank attempts to lower unemployment, its actions can initially shift the short-run Phillips curve. However, as people adapt to the resulting increase in inflation, the long-run Phillips curve may shift outward.

This is particularly true around the [natural rate of unemployment or NAIRU](https://www.investopedia.com/terms/n/naturalunemployment.asp) (Non-Accelerating Inflation Rate of Unemployment), which is the typical level of frictional and institutional unemployment. So in the long-run, if expectations can adapt to changes in inflation rates, then the long-run Phillips curve resembles a vertical line at the NAIRU; monetary policy simply raises or lowers the inflation rate aftermarket expectations have worked themselves out.

During stagflation, people might expect inflation to rise if they learn that monetary policy will expand. This can cause an outward shift in the short-run Phillips curve even before the expansionary monetary policy has been carried out, so that even in the short run, the policy has little effect on lowering unemployment, and in effect, the short-run Phillips curve also becomes a vertical line at the NAIRU.

## Why Would an Economist Still Believe in the Phillips Curve?

Despite its limitations, some economists still find the Phillips curve useful. Policymakers may use it as a general framework to think about the relationship between inflation and unemployment, both key measures of economic performance. Others caution that it does not capture the complexity of today's markets.

## Why Does Ongoing Debate About the Relevance of the Phillips Curve Matter?

Disagreements over the dependability of the Phillips curve can result in different economic policies. For instance, a policymaker who believes that lower unemployment is linked to higher inflation may seek to implement measures to keep inflation down, such as raising interest rates. Another policymaker might not agree with such a response.

## Why Has the Phillips Curve Flattened?

Sometimes, unemployment falls while inflation stays low, indicating a "flattening" of the Phillips curve. This can partly be due to the Federal Reserve's efforts to keep inflation low and stable, weakening the link between inflation and the job market.

## The Bottom Line

The Phillips curve is an economic theory positing an inverse relationship between inflation and unemployment. It resonated with economists in the 20th century, but became increasingly disputed in the 1970s, which saw rising unemployment and inflation simultaneously. Today, economists have adapted new models to explain the relationship between unemployment and inflation. However, some economists still maintain that the Phillips curve is useful to consider, despite its limitations.

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