Externalities · 外部性
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| externality/ekˈstɜːnælɪti/ | 外部性 | wài bù xìng |
| negative externality/ˈneɡətɪv ekˈstɜːnælɪti/ | 负外部性 | fù wài bù xìng |
| third party/θɜːd ˈpɑːti/ | 第三方 | dì sān fāng |
| marginal private cost/ˈmɑːdʒɪnl ˈpraɪvət kɒst/ | 边际私人成本 | biān jì sī rén chéng běn |
| overproduces/ˌəʊvəprəˈdjuːsɪz/ | 过度生产 | guò dù shēng chǎn |
| positive externality/ˈpɒzɪtɪv ekˈstɜːnælɪti/ | 正外部性 | zhèng wài bù xìng |
| marginal private benefit/ˈmɑːdʒɪnl ˈpraɪvət ˈbenɪfɪt/ | 边际私人收益 | biān jì sī rén shōu yì |
| underproduces/ˌʌndəprəˈdjuːsɪz/ | 生产不足 | shēng chǎn bù zú |
| Pigouvian tax/pɪˈɡuːvɪən tæks/ | 庇古税 | bì gǔ shuì |
| subsidy/ˈsʌbsɪdi/ | 补贴 | bǔ tiē |
| tradable permits/ˈtreɪdəbl ˈpɜːmɪts/ | 可交易许可证 | kě jiāo yì xǔ kě zhèng |
The cost you don't pay
- A factory's smoke drifts over a neighbourhood the owner never meets.
- A vaccine protects not just you, but everyone you don't infect.
- These spillovers land on people outside the deal — and the market ignores them.
- Each one is an externality 外部性, and it makes the market produce the wrong amount.
你没付的那份成本
- 工厂的烟飘过一个厂主从未谋面的社区。
- 疫苗保护的不只是你,还有所有你没有传染的人。
- 这些外溢落在交易之外的人身上——而市场对它们视而不见。
- 每一个都是外部性(externality),它让市场生产错误的数量。
An externality is a cost or benefit that falls on: · 外部性是落在谁身上的成本或收益:
The spillover lands on someone outside the buyer-seller deal. · 外溢落在买卖双方之外的人身上。
Negative and positive externalities
- A negative externality 负外部性 (pollution) imposes a cost on a third party 第三方. Marginal social cost sits above the marginal private cost 边际私人成本, so the market overproduces 过度生产.
- A positive externality 正外部性 (vaccination) gives others a benefit. Marginal social benefit sits above the marginal private benefit 边际私人收益, so the market underproduces 生产不足.
负外部性与正外部性
- 负外部性(negative externality,污染)给第三方(third party)带来成本。边际社会成本高于边际私人成本(marginal private cost),所以市场过度生产(overproduces)。
- 正外部性(positive externality,疫苗接种)给他人带来收益。边际社会收益高于边际私人收益(marginal private benefit),所以市场生产不足(underproduces)。
An externality · 一个外部性
A negative externality puts social cost above private cost, so the market overproduces. A tax equal to the external cost restores the efficient quantity. · 负外部性使社会成本高于私人成本,所以市场过度生产。一道等于外部成本的税恢复有效率的数量。
A good with a negative externality (like pollution) is: · 带有负外部性的商品(如污染)会被:
The firm ignores the extra social cost, so it makes more than the efficient quantity. · 企业忽略额外的社会成本,所以生产得比有效率的数量多。
A good with a positive externality (like vaccination) is underproduced by the market. · 带有正外部性的商品(如疫苗接种)会被市场生产不足。
Buyers ignore the benefit to others, so the market makes too little. · 买家忽略了给他人的收益,所以市场生产得太少。
How governments correct them
- A Pigouvian tax 庇古税 equal to the external cost raises the polluter's private cost to the social cost, cutting output to the efficient level.
- A subsidy 补贴 equal to the external benefit encourages more of a good thing (like education).
- Tradable permits 可交易许可证 cap total pollution and let firms trade the right to pollute, so cuts happen where they are cheapest.
政府如何纠正
- 庇古税(Pigouvian tax)等于外部成本,把污染者的私人成本抬到社会成本,把产量削到有效率的水平。
- 补贴(subsidy)等于外部收益,鼓励多做好事(比如教育)。
- 可交易许可证(tradable permits)给总污染设上限,让企业交易污染权,使削减发生在成本最低的地方。
A tax set equal to the external cost of pollution is called a ______ tax. · 设为等于污染外部成本的税,叫做______税。
A Pigouvian tax internalises the externality, cutting output to the efficient level. · 庇古税把外部性内部化,把产量削到有效率的水平。
Select all · 所有 tools a government can use to correct externalities. · 选出政府可用于纠正外部性的所有工具。
Taxes, subsidies and permits all make people face the full social cost or benefit. · 税、补贴和许可证都让人们面对完整的社会成本或收益。
A worked case
- A factory's private cost of a tonne of steel is 200, but its smoke does 30 of harm to residents.
- So the true social cost is $200 + 30 = 230$; left alone, the factory ignores the 30 and overproduces.
- A Pigouvian tax of exactly 30 makes the factory pay the full 230.
- The tax "internalises" the externality, cutting output to the efficient amount.
一个例子
- 工厂生产一吨钢的私人成本是 200,但它的烟给居民造成 30 的损害。
- 所以真实的社会成本是 $200 + 30 = 230$;放任不管,工厂忽略那 30、过度生产。
- 一道恰好 30 的庇古税,让工厂支付完整的 230。
- 这道税把外部性"内部化",把产量削到有效率的数量。
A tonne of steel has a private cost of 200 and does 30 of harm to others. What per-tonne Pigouvian tax makes the firm face the full social cost? · 一吨钢的私人成本是 200,给他人造成 30 的损害。每吨多大的庇古税能让企业面对完整的社会成本?
The tax equals the external cost, 30, so the firm pays the full social cost of 230. · 税等于外部成本 30,所以企业支付完整的社会成本 230。
An externality spills a cost or benefit onto a third party. A negative one (social cost above private) causes overproduction; a positive one (social benefit above private) causes underproduction. Governments fix them with a Pigouvian tax, a subsidy, or tradable permits.
外部性把成本或收益外溢给第三方。负外部性(社会成本高于私人)造成过度生产;正外部性(社会收益高于私人)造成生产不足。政府用庇古税、补贴或可交易许可证来纠正。