Key Definitions
- Free Goods: Goods with zero opportunity cost because they are abundant
- Private (Economic) Goods: Goods that are scarce and have an opportunity cost
- Public Goods: Goods that are non-rival and non-excludable
- Merit Goods: Goods that are under-consumed due to imperfect information
- Demerit Goods: Goods that are over-consumed due to imperfect information
- Rivalry: Consumption by one reduces availability for others
- Excludability: Ability to prevent non-payers from consuming a good
Free Goods vs Economic Goods
Free Goods
- Abundant in supply
- No opportunity cost
- Not scarce
Examples: Air (in most contexts), sunlight
Economic Goods
- Scarce and have opportunity cost
- Usually rival and excludable
- Allocated through the price mechanism
Analytical Link
Scarcity → price charged → consumers must choose → opportunity cost arises
Public Goods
Public goods are non-rival and non-excludable.
- Non-rival: One person’s consumption does not reduce availability for others
- Non-excludable: It is not possible to prevent non-payers from consuming
Examples
- Street lighting
- National defence
Analysis: Why Markets Fail
Non-excludability → free rider problem → individuals avoid paying → firms cannot earn revenue → under-provision or no provision
Analytical Chain
Non-excludable → no incentive to pay → firms cannot charge → market fails → government provision required
Merit Goods
Merit goods are goods that are under-consumed in a free market because consumers underestimate their benefits.
Cause: Imperfect Information
Consumers lack full knowledge of the benefits.
Examples
- Education
- Healthcare
Analysis
Imperfect information → consumers underestimate benefits → demand is too low → under-consumption → welfare loss
Analytical Chain
Lack of information → lower perceived benefit → reduced demand → under-consumption → allocative inefficiency
Demerit Goods
Demerit goods are goods that are over-consumed in a free market because consumers underestimate their costs.
Cause: Imperfect Information
Consumers are unaware of full harmful effects.
Examples
- Tobacco
- Alcohol
Analysis
Imperfect information → consumers underestimate harm → demand is too high → over-consumption → welfare loss
Analytical Chain
Lack of awareness → underestimated costs → excessive demand → over-consumption → allocative inefficiency
Developed Analysis
- Public goods are not efficiently allocated by markets due to the free rider problem, leading to under-provision
- Merit goods are under-consumed because consumers fail to recognise their long-term benefits
- Demerit goods are over-consumed because consumers underestimate negative consequences
Evaluation
Degree of Rivalry/Excludability
Some goods are not purely public or private (e.g. quasi-public goods), making classification less clear
Information May Improve
Education and advertising can reduce imperfect information, changing consumption patterns
Government Failure
Government provision of merit/public goods may be inefficient or misallocated
Changing Nature of Goods
Technology can make goods more excludable (e.g. subscription services)
Subjectivity of Merit/Demerit Goods
What is considered “merit” or “demerit” may vary across societies and individuals
Common Mistakes
- Defining public goods without mentioning both non-rivalry and non-excludability
- Confusing merit goods with public goods
- Ignoring the role of imperfect information
- Giving examples without explanation
- Not linking to under- or over-consumption
Exam Tips
- Always define using key characteristics (rivalry and excludability)
- Use clear analytical chains:
- Merit goods → under-consumption
- Demerit goods → over-consumption
- Apply real-world examples with explanation
- Include evaluation (e.g. government failure, subjectivity)
- Link to market failure where relevant