Q.Explain why public goods must be provided by the government.

You are walking home with a friend who bought a pack of biscuits. She opens it and starts eating. You can smell the biscuits from a metre away. Can she stop you from enjoying that smell? No. And if she eats one biscuit, is there less biscuit left for her? Yes. That simple difference is the entire foundation of public goods.

The Two Key Properties

Economists classify goods based on two questions:

1. Rivalry: If I consume one unit, does that leave less for you? (A biscuit is rival – once eaten, it's gone. A song on the radio is non-rival – my listening doesn't reduce it for you.)
2. Excludability: Can the seller prevent you from consuming it if you don't pay? (A cinema ticket is excludable – no ticket, no entry. A lighthouse beam is non-excludable – you can't stop a ship from seeing it.)

A public good is a good that is both non-rival and non-excludable.

The classic textbook example is national defence. If the army protects the country from invasion, it protects everyone within the borders. My being protected does not reduce the protection you get (non-rival). And you cannot be excluded from that protection even if you refuse to pay taxes (non-excludable).

Another example is clean air. Everyone breathes the same air. One person breathing doesn't use it up, and you can't stop someone from breathing.

The Problem: The Free Rider

Here is where the trouble begins. Because a public good is non-excludable, a rational person thinks: "Why should I pay for it? I will get the benefit anyway, whether I pay or not."

This is the free rider problem. If everyone thinks this way, no one pays. The good is either not provided at all, or is provided at a much lower level than society actually wants.

Think of a streetlight in your colony. If the residents are asked to voluntarily contribute money to install it, many will say, "I can see from my window just fine without paying. Let others pay." If everyone does that, the streetlight never gets installed, even though everyone would be better off with it.

The Solution: Government Provision

Because the market fails to provide public goods efficiently, the government steps in. It uses its power of taxation to force everyone to contribute. The tax is the "price" you pay for the public good, whether you wanted it or not.

The government then decides how much of the public good to provide. This is a difficult decision because there is no market price to signal what people want. The government must use tools like cost-benefit analysis or voting to decide the optimal level.

A Diagram in Words

Imagine a graph with Quantity of the public good on the x-axis and Price (or Benefit) on the y-axis.

• There is a demand curve for each individual. But unlike a private good, you don't add the quantities demanded by each person. Instead, you vertically sum their willingness to pay. Why? Because everyone consumes the same unit. If I am willing to pay ₹100 for one unit of national defence and you are willing to pay ₹50, the total social benefit of that one unit is ₹150.
• The social demand curve is the vertical sum of all individual demand curves.
• The supply curve (marginal cost) is the cost of providing one more unit.
• The efficient quantity is where the social demand curve (total marginal benefit) equals the marginal cost.

The free rider problem means that the revealed demand (what people actually pay for) is far lower than the true social demand. So the market under-provides the good.

The Bottom Line for Your Exam

When you see "public goods provision" in your NCERT textbook, remember the two properties. The entire concept is about a market failure caused by non-excludability, and the government's role in correcting it through taxation and collective provision. There is no formula to memorise here – just a clear logical chain: Non-excludability → Free rider → Market failure → Government provision.