How Ice Cream Prices Help Explain a Nobel-Winning Economic Idea
An ice cream menu can show why some prices change slowly, even when the economy shifts quickly. That simple idea helped shape a major approach to understanding recessions, jobs, and inflation. The economists Robert Hall and Michael Woodford were honored for work that helped build this approach, known as New Keynesian economics.
Why Prices Can Be “Sticky”
Businesses do not always change prices as soon as costs or customer demand change. An ice cream shop may print a menu for a whole season instead of updating prices every day. Changing signs and menus takes time and money. The owners may also wait to learn whether a drop in sales will last.
Economists call prices that are slow to change sticky prices. The same idea applies to wages. Many workers do not get a new wage every month, even when the economy is changing.
This delay can matter across the economy. If customers spend less, businesses may not lower prices right away. They may sell fewer products instead. Then they may cut workers’ hours or lay people off. When prices and wages do not adjust quickly, fewer people may be able to work, even if they want a job.
Keynes’s Idea About Recessions
John Maynard Keynes helped create the modern study of the whole economy, including employment, inflation, and government action. During the Great Depression, he argued that an economy could remain in a deep slump for a long time. He did not believe that markets would always bring jobs and spending back on their own.
Keynes argued that government could help by increasing spending and supporting employment. This view challenged the belief that people and businesses acting in their own interests would naturally bring the economy to its best possible state. That belief is often described as the “invisible hand” of the market.
Keynes’s ideas shaped economic thinking for many years. But later, economists faced a serious problem: the old models had trouble explaining a period when high inflation and high unemployment happened at the same time. This painful mix is called stagflation.
Why Economists Wanted New Models
Some economists argued that older Keynesian models did not explain enough about how individual people and businesses make choices. People look ahead and form expectations. They may change how they spend, save, or invest when they expect the government to change its policies. Because behavior can shift, patterns from the past may not reliably predict what a new policy will do.
Economists responded by trying to build models from the choices of individuals and businesses. This approach is called giving economic models microfoundations. The goal was to explain how personal decisions add up to shape the entire economy.
One competing approach, called real business cycle theory, assumed that prices and wages could adjust freely. If employers needed fewer workers, wages could fall, making it cheaper to hire. In that view, the labor market could balance itself, leaving less room for long periods when people wanted jobs but could not find them.
Hall and Woodford helped address these debates rather than simply reject Keynes’s ideas. Hall studied how people’s beliefs about the future affect their spending today. Woodford developed those insights into a framework that also allowed prices to change slowly.
How Sticky Prices Can Deepen a Slump
Imagine that a recession causes people to buy less ice cream. If a shop keeps its prices unchanged, it may sell fewer scoops instead of quickly attracting buyers with lower prices. The shop could respond by reducing work hours or cutting jobs. Similar choices happen across many industries, and wages may also stay in place while businesses reduce hiring.
When spending falls and prices and wages are slow to respond, businesses may make fewer goods and services and employ fewer people. The economy can stay weak. In this kind of model, the market does not always correct a downturn quickly, which leaves room for public policy to help.
New Keynesian economics combines two ideas: people and businesses make forward-looking choices, and prices and wages can be slow to adjust. This gives economists a way to take criticism of older models seriously while keeping Keynes’s central point that a free market may not recover from every slump by itself.
Why the Framework Matters Today
New Keynesian models became important to how governments and central banks think about recessions and inflation. They help explain why policy can affect demand, jobs, and business decisions when prices do not move quickly.
Woodford’s work also helped provide a foundation for forward guidance, in which a central bank signals what it expects to do in the future. During the Great Recession, the Federal Reserve lowered its main interest rate close to zero. It also signaled that rates would likely stay low for an extended period. The aim was to shape expectations, reduce longer-term borrowing costs, and encourage people and businesses to spend.
The ice cream menu offers a small example of a larger economic problem: when prices and wages are slow to change, a drop in spending can hurt jobs and production. That insight helped give Keynes’s ideas a new foundation and continues to influence how policymakers think about keeping the economy on track.