The assumptions of Marshall’s model create certain consequences for firms in perfectly competitive industries. One of the most important of these is that firms have no power over the price that they can charge. This is because there are so many firms selling an identical product that if any one firm attempts to sell at a price higher than its competitors, it will sell nothing. This is virtually guaranteed because the consumer has perfect knowledge about the prices being asked by all firms. In this way the market price is determined by the collective interaction of all the firms and consumers, and each firm has to accept that one particular price is the price at which they can sell the product. They have to “take” the price, not make it.
In the late 18th century Adam Smith wrote about the impact of competition on firms’ abilities to set prices and make profits above a “natural” level.
However, there was no formal analysis of the situation until British economist Alfred Marshall published Economic Principles in 1890. The ideas in Marshall’s model remain a key part of mainstream economic theory, although the theory has been criticized as not representing the true nature of competition.
The “elasticity” of demand is its responsiveness to changes in another factor, such as price. British economist Alfred Marshall is generally credited as the first economist to define the concept in 1890, but the German statistician Ernst Engel published a paper five years earlier, showing how changes in income alter the level of demand. The origins of the concept may be disputed, but its importance is not.
There has long been something appealing for economists about the idea that the economy may behave with the same mathematical predictability of scientific laws such as Newton’s laws of motion. Newton’s laws reduce the whole complex, teeming, physical universe to three simple, reliable mathematical relationships. Is it possible to find similar relationships in the complex, changing world of markets?
Figure 2.1 depicts Model I. Here, we imagine an economy that produces only consumption goods. To keep Model I as simple as possible we further suppose that the only consumption good is cars. These cars are produced by firms which are staffed by the households and owned by the households.
To put it in the language of economics, the two factors of production are labor and capital, and the households own both of them. There is no role for government or for the rest-of-the-world in Model I, so these sectors are omitted.