The New-Keynesian View on Real Business Cycles

Understanding how economies move through boom and bust cycles has been a central challenge in economics. For decades, economists have debated why markets sometimes fail to self-correct and whether government intervention can help stabilize economic fluctuations. The New-Keynesian view on business cycles emerged as a sophisticated response to these questions, incorporating modern economic theory while maintaining a key insight: markets don’t always clear instantly, and that matters for policy.

Building better foundations: responding to the Lucas Critique 🔗

In the 1970s, economist Robert Lucas raised a fundamental criticism of traditional Keynesian models. His critique pointed out that when policymakers change their approach, people adjust their behavior accordingly, which means economic relationships observed in historical data may not remain stable under new policies. This observation, known as the Lucas Critique, challenged economists to build models where individual decision-making was explicitly modeled rather than simply assumed.

New-Keynesian economists took this criticism seriously. Unlike earlier Keynesian approaches that sometimes took price stickiness as a given without deep explanation, the New-Keynesian school worked to provide microeconomic foundations that demonstrate how price stickiness emerges from optimal decision-making by firms and workers. They incorporated rational expectations-the idea that people use available information efficiently when forming predictions about the future-directly into their models, just as new-classical economists had advocated.

Think of it this way: if you’re running a restaurant and the government announces a new economic policy, you’re not going to keep pricing your menu the same way if you understand how that policy will affect your business. New-Keynesian models account for this forward-looking behavior while still explaining why prices might not adjust immediately.

The crucial difference: rejecting continuous market clearing 🔗

Here’s where New-Keynesian economics parts ways with new-classical thinking. While both schools embrace microfoundations and rational expectations, they disagree fundamentally about how quickly markets adjust to changes. New-classical economists typically assume that prices and wages adjust rapidly to clear markets-meaning supply equals demand almost instantly. In their view, unemployment exists mainly because people are voluntarily choosing not to work at current wage rates, or are between jobs.

New-Keynesian economists reject this assumption. They argue that various market imperfections prevent wages and prices from adjusting instantaneously to changes in economic conditions. When demand drops suddenly, firms can’t immediately lower prices without cost, and workers can’t instantly renegotiate wage contracts. This means markets may not clear in the short run, leading to involuntary unemployment and economic slack.

Imagine a factory where workers have annual contracts. If demand for the factory’s products suddenly falls, the firm can’t immediately cut wages to reflect this. Workers who would be willing to work for less to keep their jobs can’t easily renegotiate. This temporary mismatch between supply and demand represents a market failure that wouldn’t exist if prices and wages adjusted instantaneously.

Why this matters for understanding recessions 🔗

The rejection of continuous market clearing fundamentally changes how we understand business cycles. If markets always cleared instantly, recessions would simply represent optimal responses to real changes in the economy-perhaps new technologies or shifts in consumer preferences. But if market imperfections prevent instant adjustment, then recessions can represent failures in coordination where resources sit idle even though people want to work and consumers want to buy.

Modeling the frictions: menu costs and staggered contracts 🔗

To explain why prices don’t adjust immediately, New-Keynesian economists developed sophisticated models incorporating various “frictions” in the economy. One important concept is menu costs-the idea that changing prices involves real costs for firms, from printing new catalogs to updating computer systems. When these costs are significant enough, firms may choose to keep prices unchanged even when economic conditions shift.

But menu costs alone aren’t sufficient. New-Keynesian models also incorporate staggered price and wage setting, based on research by economists like Stanley Fischer, John Taylor, and Guillermo Calvo. These models recognize that not all firms change prices at the same time. Some companies reset prices quarterly, others annually, and they don’t all do so in January. This staggering means that even if individual firms could adjust prices costlessly, they might be reluctant to do so if other firms’ prices haven’t changed yet.

Consider a shopping mall with many competing stores. If your store is the only one to raise prices sharply, you’ll lose customers to competitors. So even if your costs have increased, you might wait to see what others do. When everyone thinks this way, price adjustment across the economy becomes sluggish, amplifying the effects of economic shocks.

The mathematics behind the stickiness 🔗

New-Keynesian economists formalized these ideas using Dynamic Stochastic General Equilibrium (DSGE) models. These mathematical frameworks explicitly model how households and firms make optimal decisions over time while facing uncertainty and various constraints. The Calvo pricing model, for instance, assumes that in any given period, only a certain fraction of firms can reset their prices. This simple assumption generates realistic patterns of gradual price adjustment that match what we observe in actual economies.

These models also incorporate imperfect competition-the recognition that most firms have at least some pricing power rather than being pure price-takers. This matters because it creates another source of inefficiency: firms may charge prices above marginal cost, reducing overall economic welfare.

Policy implications: when markets fail to self-correct 🔗

The New-Keynesian framework has profound implications for economic policy. If wage and price rigidities mean that markets don’t automatically return to full employment after a shock, then there’s potentially a role for government and central bank intervention. When aggregate demand falls and prices can’t adjust downward quickly, the economy can get stuck with high unemployment and idle capacity.

Unlike new-classical models where government stabilization policies are generally counterproductive, New-Keynesian models suggest that macroeconomic stabilization through monetary and fiscal policy can lead to more efficient outcomes. If the central bank lowers interest rates when demand is weak, it can help bridge the gap until prices adjust. Similarly, fiscal stimulus might help maintain aggregate demand during recessions.

However, New-Keynesian economists don’t advocate reckless policy intervention. Their models emphasize the importance of credible, rule-based policy frameworks. The famous Taylor Rule, which describes how central banks should adjust interest rates in response to inflation and output gaps, emerged from New-Keynesian thinking. The key insight is that systematic, predictable policy responses work better than discretionary actions because people can anticipate them when forming expectations.

The ongoing debate about policy effectiveness 🔗

While New-Keynesian models justify activist policy, they also highlight its limitations. Money remains neutral in the long run-changing the money supply ultimately just changes the price level without affecting real economic activity. It’s only in the short run, while prices are sticky, that monetary policy has real effects. This means policy is best used for stabilization rather than trying to permanently boost output above its natural level.

Methodological similarities with important differences 🔗

It’s worth emphasizing what New-Keynesian and new-classical economics share. Both approaches use sophisticated DSGE models built on microeconomic foundations. Both assume that people have rational expectations and make optimal decisions given the information available to them. Both employ similar mathematical techniques and modeling strategies.

The critical difference lies in their assumptions about how markets function. New-classical models typically assume flexible prices and continuous market clearing, leading to the conclusion that observed fluctuations represent efficient responses to real shocks, with little role for stabilization policy. New-Keynesian models, by contrast, embed nominal and real rigidities that prevent instant market clearing, opening the door for policy to improve outcomes.

Think of it as two architects using the same blueprint software but designing very different buildings. The tools are similar, but the underlying philosophy about how economic structures should function differs fundamentally. This difference in assumptions about market clearing mechanisms leads to vastly different conclusions about the appropriate role of policy.

The continuing evolution 🔗

Today, most mainstream macroeconomists work within what’s called the “new neoclassical synthesis,” which incorporates elements from both traditions. Modern central bank models typically include New-Keynesian features like sticky prices and imperfect competition alongside new-classical elements like intertemporal optimization and rational expectations. This synthesis represents recognition that both perspectives offer valuable insights-markets do tend toward equilibrium over time, but that journey isn’t always smooth or quick.

What do you think? If you were designing economic policy, would you place more weight on New-Keynesian concerns about market failures and the need for intervention, or on new-classical warnings about the limits of policy effectiveness? How might your answer differ depending on whether you’re thinking about normal times versus severe crises?

References

1. https://en.wikipedia.org/wiki/Lucas_critique
2. https://en.wikipedia.org/wiki/New_Keynesian_economics
3. https://www.economicsdiscussion.net/business-cycles/business-cycles-new-classical-and-new-keynesian-macroeconomics/15991
4. https://en.wikipedia.org/wiki/Menu_cost
5. https://en.wikipedia.org/wiki/Dynamic_stochastic_general_equilibrium
6. https://www.econlib.org/library/Enc/NewKeynesianEconomics.html