derived demand

Nobody hires a steelworker because they enjoy having a steelworker around. A car company hires steelworkers because people want cars, and cars need steel, and steel needs steelworkers. The demand for the worker is not wanted for its own sake — it is pulled along, second-hand, by the demand for the final product. That borrowed, second-hand wanting is called derived demand.

Precisely, derived demand is the demand for a factor of production (or any input) that arises only because there is demand for the goods that input helps to make. It flows backward through the supply chain. Demand for houses creates demand for bricklayers, lumber, and cranes. Demand for coffee creates demand for coffee beans, baristas, and espresso machines. If the demand for the final good rises, the demand for every input it uses tends to rise with it; if the final good falls out of fashion, its inputs lose their buyers too. This is why a slump in car sales quickly becomes layoffs in steel and tyre plants.

The idea is the engine behind almost everything in labour and factor markets. It explains why wages ultimately depend on how much consumers value what workers produce, not on how hard the work feels. It is also why predicting input demand means looking one step downstream: to know whether software engineers will be in demand, ask whether the products built with software will be in demand. A common mistake is to treat input demand as fixed — in reality it rises and falls with the popularity of the final product.