Nobody decides how many loaves of bread London needs tomorrow. No committee meets, no quota is issued, and yet the bread appears, roughly in the right quantity, in roughly the right places. Somewhere else, a planning ministry with thousands of staff and detailed statistics struggles to get shoes to the right cities in the right sizes. How a society answers what to produce, how, and for whom is the question that separates economic systems, and the answers perform very differently.
Before the systems, one distinction. Microeconomics studies individual parts of the economy: a single market, a firm, a household, the price of one good. Macroeconomics studies the economy as a whole: total output, the general price level, unemployment, the balance of payments. The division matters because what holds for a part need not hold for the whole. One household saving more becomes richer; every household saving more at once can reduce national income and leave total saving unchanged. Assuming otherwise is the fallacy of composition.
Market economic system
An economic system in which resources are allocated through the price mechanism, with production and consumption decisions made privately by firms and households rather than by the state.
The price mechanism allocates resources through three functions working together. Prices signal, carrying information about relative scarcity to everyone in the market without anyone having to collect it. Prices incentivise, since a higher price rewards producers for supplying more and encourages consumers to economise. And prices ration, because when something is scarce its price rises until only those willing to pay the most obtain it. The remarkable feature is that no participant needs to understand the system for it to work: a farmer responding to a higher wheat price does not need to know why it rose.
Questions on the price mechanism expect the three functions named as signalling, incentives and rationing. An answer describing how price rises when demand increases has described the mechanism without naming its functions, and typically earns half the marks available. Name each function and give it a sentence.
A market system has real advantages. Consumer sovereignty means what gets produced is determined by what people actually buy. Competition drives efficiency, because firms that waste resources are undercut. The profit motive rewards innovation, and firms that develop better products prosper. And the system needs no central administration, so the enormous costs of collecting information and issuing instructions are avoided entirely.
The disadvantages are the reason no pure market economy exists. Public goods such as street lighting and defence are not provided at all, because nobody can be made to pay for them. Merit goods such as healthcare and education are under-consumed, and demerit goods over-consumed. Externalities mean pollution is ignored because the polluter does not pay. Inequality can be extreme, since the market distributes according to ability to pay, and those with nothing to sell receive nothing. Monopolies form and exploit consumers. And the system can be unstable, swinging between boom and slump.
A planned economy places the state in charge of the three questions. Its potential advantages mirror the market's failures: public and merit goods can be provided directly, income distributed more equally, monopoly exploitation avoided, unemployment prevented by direction of labour, and long-term priorities pursued without regard to short-term profit. Its weaknesses are severe in practice. Planners cannot gather or process the information the price mechanism handles automatically, so shortages and surpluses are chronic. Without the profit motive there is little incentive to innovate or control costs. Consumers get what is planned rather than what they want. And the administrative apparatus is itself enormously costly.
Almost every real economy is mixed, combining private markets with government intervention, and the interesting question is never which system but where the boundary falls. Governments typically provide public goods, subsidise or supply merit goods, tax demerit goods, regulate monopoly and externalities, redistribute income, and manage the economy as a whole. Markets typically handle everything else. Economies differ enormously in where they place the line, and that placement is the substance of most political disagreement about economics.
Tracing the price mechanism through a supply shock
A disease destroys a third of a country's coffee crop. Trace how the price mechanism reallocates resources, identifying where each of the three functions operates.
In a market economy, what determines which goods are produced?
Which is a disadvantage of a planned economy rather than of a market economy?
Draw a demand and supply diagram for a good and show a leftward shift of supply. Mark the original equilibrium, the shortage that appears at the old price, and the new equilibrium. Annotate the diagram to show where rationing, signalling and incentives are operating.
Annotating the three functions onto the diagram is the habit worth building, because it converts a mechanical shift into an explanation of how resources get reallocated. The shortage at the old price is the part most often left off, and it is what actually drives the price upward.