The price mechanism is impressive, but it is not perfect. It ignores pollution, it prices some people out of essentials, and it collects no money for schools or hospitals. Every real economy therefore mixes free markets with government action.
📘 What you need to know
Almost every country runs a mixed economy: markets do most of the work, governments step in where markets fall short.
Five main reasons to intervene: correct market failure, raise revenue, promote equity, support firms, support poorer households.
Market failure means the market allocates resources badly from society’s point of view — too much of some things, too little of others.
Firms and consumers chasing self-interest will not fix this themselves, which is what creates a role for government.
Equity is a normative idea (what people think is fair), while efficiency is positive. Keep them apart.
The four tools you meet in this topic: indirect taxes, subsidies, price ceilings and price floors, plus regulation, direct provision and nudges.
Every intervention has costs as well as benefits — that is where evaluation marks come from.
The five reasons
Exam questions rarely ask for all five. They give you a situation and expect you to pick the right one and explain it properly.
A tobacco tax, for example, aims at market failure and at revenue at the same time — and the two aims quietly pull against each other.
1. Correct market failure
In some markets, resources end up in the wrong place from society’s point of view. Too much is produced of things that harm other people, like fuel that pollutes, and too little of things that help everyone, like vaccinations or education. Buyers and sellers are each doing what is best for themselves, so nothing about the market will fix it on its own. That gap is exactly where a government has a job to do.
2. Raise government revenue
Roads, courts, schools and hospitals all cost money. Taxes on goods, on income and on company profits pay for them, alongside things like selling licences to use mobile phone frequencies. Indirect taxes on goods with inelastic demand are especially popular, because the revenue keeps arriving even after the price rises.
3. Promote equity
Equity means fairness, and it is a normative idea — people disagree about how much is right. It is also not the same as equality. Governments pursue it with minimum wage laws, health and safety rules, competition law that stops firms exploiting customers, and environmental protection.
4. Support firms
Governments often help key industries stay competitive, through subsidies, tax breaks or protection from foreign competitors while an industry finds its feet. The argument is jobs and long-run capability; the counter-argument is that protected firms can become lazy.
5. Support poorer households
Poverty damages both the individual and the wider economy. Progressive taxes take proportionally more from higher earners, and welfare payments transfer some of it back, which redistributes income and softens the effect of unemployment or illness.
Efficiency and equity are different tests. A market can be perfectly efficient and still leave people unable to afford food. When a question asks you to evaluate, checking both tests separately is a quick way to sound like an economist.
The toolkit
The rest of this topic works through the main tools. Each one changes the market in a different way, and each has a downside.
Knowing which curve a policy moves — or whether it moves any curve at all — is half the battle in the diagram questions coming up.
WORKED EXAMPLE
A government introduces free school meals for children from low-income families. Identify the reasons for intervention and explain one drawback. [4]
Step 1: name the reasonsSupporting poorer households, promoting equity, and correcting market failure.Step 2: explain the market failure part
Well-fed children learn better, and society gains from that later. Families acting alone do not take those wider gains into account, so the market under-provides.
Step 3: the drawbackOpportunity cost. The money could have gone to clinics or teacher training, and it must come from taxes somewhere.
Equity plus market failure, at the cost of other spendingNaming an opportunity cost is the fastest evaluation point in this whole topic.
Government failure is a thing too. Intervention can go wrong: policies get set at the wrong level, information is poor, and lobbying pushes policy towards whoever shouts loudest. Mentioning this lifts an evaluation paragraph.
💡 Exam tip
Say which reason applies, do not list all five. Two well-explained reasons beat five named ones.
Use the phrase “from society’s point of view” when defining market failure. It is exactly what the term means.
Label equity as normative. It shows you can tell value judgements from facts.
Every intervention costs something. Opportunity cost, unintended effects and government failure are your three ready-made evaluation points.
Tie the policy to a diagram whenever you can — even a quick sketch of a shifting supply curve earns marks.
Remember that “mixed economy” is the norm. No exam answer should suggest a country is purely one or the other.
⚠ Common mix-up
Treating equity and equality as the same word. Equity is about fairness, and people disagree on what that means.
Saying markets always fail. They usually work well; intervention targets the cases where they do not.
Assuming government action always improves things. Government failure is a real possibility.
Forgetting the money has to come from somewhere. Subsidies and provision have an opportunity cost.
Confusing indirect taxes with income tax. Indirect taxes are paid on goods when they are bought.
Describing a policy without naming the reason for it. Questions usually ask why, not just what.
Up next: Indirect Taxes and Subsidies — the two tools that work by moving the supply curve, and the diagrams examiners ask for most often.
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