Chapter 6 · Market failure and socially undesirable outcomes II: Positive externalities, public goods, asymmetric information and inability to achieve equity
Direct provision: beneficial production
Explore direct public provision when production benefits third parties. Compare total output with the socially efficient quantity and discuss limits.
The economic idea
Direct provision occurs when government produces or supplies output rather than relying entirely on private firms. It may be delivered by public organisations, commissioned providers or publicly funded institutions.
With a positive production externality, marginal social cost lies below marginal private cost because production creates benefits for third parties. Private firms cannot charge every beneficiary and therefore produce below the social quantity.
The intervention adds a quantity of publicly provided output alongside private supply. Total output rises and the market price may fall, while some private production is crowded out.
This differs from a producer subsidy: a subsidy changes the incentive on each private unit, whereas direct provision creates public units using labour, capital and other real resources.
Q* remains a useful pre-policy benchmark, but the final welfare result depends on the resource cost and quality of public output. Adding units beyond Q* is not automatically inefficient if provision changes technology or benefit, and reaching Q* is not automatically efficient if public delivery is unusually costly.
Reading public output that leaves total production below Q*
“Price” is measured vertically and “Quantity” horizontally.
“MSB = MPB” represents marginal private benefit and “MSB = MPB” marginal social benefit.
“MPC” represents marginal private cost and “MSC” marginal social cost.
“S + government provision” shows the intervention currently applied. The combined provision schedule represents a fixed quantity of public output, not a subsidy or a general fall in private firms’ production costs.
Before intervention: Eₘ
“Eₘ” is the private-market equilibrium, where “MSB = MPB” meets “MPC”, giving “Pₘ” and “Qₘ”.
Social benchmark: E*
“E*” is where “MSB = MPB” meets “MSC” and gives “Q*”. Because public provision changes the production structure, “Q*” is a pre-policy benchmark rather than automatic proof of the final optimum.
Post-intervention outcome: E₂
Government adds output alongside private supply, increasing total production and potentially displacing part of private production. The resulting outcome is “E₂” at “P₂” and “Q₂”. “Q₂” is above “Qₘ” but remains below “Q*”. The intervention reduces underprovision without eliminating it.
What the intervention changes, and what it does not show
Government adds production capacity, represented by “S + government provision”, rather than paying a per-unit subsidy to existing firms. Public output still uses resources, so a supply expansion is not proof that its full social cost has fallen by the same amount.
“Q*” is a benchmark from the original production structure. Judge the new mix of public and private output using its costs, quality and external benefits; do not automatically call extra output beyond that benchmark either efficient or wasteful.
How the direct public production changes the outcome
The market initially reaches “Eₘ” and “Qₘ” because private decision makers follow “MSB = MPB” and “MPC”.
The social comparison uses “MSB = MPB” and “MSC”, producing the benchmark “E*” and “Q*”.
Government adds output alongside private supply, increasing total production and potentially displacing part of private production.
The new intersection is “E₂” and “Q₂”. “Q₂” is above “Qₘ” but remains below “Q*”. The intervention reduces underprovision without eliminating it. Because public provision changes the production structure, “Q*” is a pre-policy benchmark rather than automatic proof of the final optimum.
What the current state establishes
“Q₂” is above “Qₘ” but remains below “Q*”. The intervention reduces underprovision without eliminating it. Because public provision changes the production structure, “Q*” is a pre-policy benchmark rather than automatic proof of the final optimum.
A rise in activity is not enough to prove success; the remaining gap to Q* represents beneficial units still forgone.
Common mistakes to avoid
- Public output is not costless and does not make MPC disappear. Its labour, capital and materials have an opportunity cost.
- The intervention is not automatically optimal because “Q₂” exceeds “Qₘ”. It must be compared with “Q*” and evaluated against its costs.
- Government expenditure is not automatically deadweight loss, but it has an opportunity cost and may require distortionary taxation.
- “Q*” is a pre-policy benchmark in this provision model, not automatic proof that every public/private output mix at that total is efficient.
How to draw this diagram
- Title the diagram “Direct provision: beneficial production”. Label the horizontal axis “Quantity” and the vertical axis “Price”.
- Draw MSB = MPB first and label it clearly.
- Draw MPC next and label it clearly.
- Draw MSC next and label it clearly.
- Draw S + government provision next and label it clearly.
- Mark each relevant intersection and distinguish the initial, market and socially optimum or policy outcomes where applicable.
- Project important intersections to the axes with dashed guide lines and label the outcomes.
- Check that every symbol used in the explanation appears on the diagram and add arrows showing the direction of change.
Assumptions and limitations
- Public and private output may be complements rather than perfect substitutes, so crowding out can be smaller than shown.
- Government agencies may face weak incentives, political objectives or limited technical capacity.
- Benefits can take years to emerge and may be difficult to attribute to the public programme.
- The model omits tax finance, administrative cost and the opportunity cost of public resources.
- The pre-policy Q* benchmark may not remain the exact optimum when public production changes costs, quality or technology.