If demand is , raising prices increases total revenue.
To understand the magnitude of Marshall’s contribution, one must look at the state of economics prior to 1890. The Classical Economists, such as David Ricardo and John Stuart Mill, often relied on a "cost of production" theory of value. They argued that the value of a good was determined by the labor and resources put into it. While they acknowledged the role of demand, they lacked the tools to quantify it accurately.
This insight revolutionized business strategy. It explains why airlines charge desperate business travelers (inelastic demand) extremely high last-minute fares, while offering cheap seats to vacationers (elastic demand) weeks in advance. Marshall’s work laid the theoretical foundation for price discrimination. alfred marshall price elasticity of demand
= % change in quantity demanded / % change in price
Marshall’s genius was in using proportional changes rather than absolute changes. By using percentages, he created a unit-free measure. This allows an economist to compare the sensitivity of demand for wildly different goods—such as a ton of steel versus a bushel of wheat—without being bogged down by the specific units of measurement. If demand is , raising prices increases total revenue
This is false. Slope measures absolute changes (ΔQ/ΔP), while elasticity measures percentage changes. A steep slope can be elastic or inelastic depending on your starting price point. Marshall was meticulous in using percentage changes to allow comparison across different goods and currencies.
: Because it uses percentages, PED allows economists to compare completely different products, like comparing how people react to the price of milk versus the price of luxury cars. | Uniwersytet Warszawski ✂️ The "Scissors" of Market Value Before Marshall, economists argued over whether (Supply) or They argued that the value of a good
Marshall used a physical metaphor from physics to describe economic behavior: just as matter can be warped by force, demand "stretches" based on price. The Decision Lab Definition
Demand remains relatively steady even if prices jump (e.g., necessities like salt or medicine).
Alfred Marshall shifted the focus from "what" people buy to "how much" their behavior changes. His contribution allows modern governments to set taxes and companies to set prices with surgical precision.
Formally, the Alfred Marshall price elasticity of demand is defined as the divided by the percentage change in price .