Socially Efficient and Inefficient Outcomes · 社会有效与无效的市场结果
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| marginal social benefit/ˈmɑːdʒɪnl ˈsəʊʃl ˈbenɪfɪt/ | 边际社会收益 | biān jì shè huì shōu yì |
| marginal social cost/ˈmɑːdʒɪnl ˈsəʊʃl kɒst/ | 边际社会成本 | biān jì shè huì chéng běn |
| socially efficient/ˈsəʊʃəli ɪˈfɪʃənt/ | 社会有效 | shè huì yǒu xiào |
| total surplus/ˈtəʊtl ˈsɜːpləs/ | 总剩余 | zǒng shèng yú |
| market failure/ˈmɑːkɪt ˈfeɪlɪə/ | 市场失灵 | shì chǎng shī líng |
| deadweight loss/ˈdedweɪt lɒs/ | 无谓损失 | wú wèi sǔn shī |
| market power/ˈmɑːkɪt ˈpaʊə/ | 市场势力 | shì chǎng shì lì |
When does a market get it right?
- A free market usually lands on an efficient outcome — but not always.
- To judge it, we ask a society-wide question about the last unit made.
- Is that unit worth more to society than it costs society?
- Answering that tells us when a market succeeds, and when it fails.
市场什么时候做对了?
- 自由市场通常会落在有效率的结果上——但并非总是如此。
- 要评判它,我们对最后一个生产出来的单位提一个全社会的问题。
- 这个单位对社会的价值,是否高于它对社会的成本?
- 回答这个问题,就能知道市场何时成功、何时失败。
Efficiency is MSB = MSC
- Marginal social benefit 边际社会收益 (MSB) is the value of one more unit to everyone.
- Marginal social cost 边际社会成本 (MSC) is the cost of one more unit to everyone.
- A market is socially efficient 社会有效 when $MSB = MSC$ — where total surplus 总剩余 is largest.
效率就是 MSB = MSC
- 边际社会收益(marginal social benefit,MSB)是多一个单位对每个人的价值。
- 边际社会成本(marginal social cost,MSC)是多一个单位对每个人的成本。
- 当 $MSB = MSC$ 时市场社会有效(socially efficient)——此时总剩余(total surplus)最大。
The efficient market · 有效率的市场
A market is efficient where marginal social benefit equals marginal social cost — the same point that maximises total surplus. · 市场在边际社会收益等于边际社会成本处有效率——也正是总剩余最大的那一点。
A market is socially efficient at the quantity where: · 市场在哪个数量处社会有效:
At MSB = MSC total surplus is maximised — the efficient quantity. · 在 MSB = MSC 处总剩余最大——有效率的数量。
At the socially efficient quantity, total surplus is as large as possible. · 在社会有效的数量处,总剩余尽可能大。
Making more or less than MSB = MSC would shrink total surplus. · 生产得比 MSB = MSC 多或少都会减少总剩余。
Market failure and deadweight loss
- Produce at any other quantity and the outcome is inefficient — a deadweight loss 无谓损失.
- A common cause is market power 市场势力: a monopoly makes too little, so valued units go unmade.
- Whenever a market can't reach the efficient quantity on its own, we call it a market failure 市场失灵.
市场失灵与无谓损失
- 在任何其他数量生产,结果都是无效率的——出现无谓损失(deadweight loss)。
- 一个常见原因是市场势力(market power):垄断生产太少,有价值的单位没被生产。
- 每当市场无法靠自己达到有效率的数量,我们就称之为市场失灵(market failure)。
When a market cannot reach the efficient quantity on its own, we call it a market . · 当市场无法靠自己达到有效率的数量时,我们称之为市场。
A market failure leaves a deadweight loss and may justify government action. · 市场失灵留下无谓损失,并可能成为政府行动的理由。
A monopoly causes a market failure mainly because it: · 垄断造成市场失灵,主要因为它:
It restricts output so valued units (worth more than MC) go unmade — a deadweight loss. · 它限制产量,使有价值的单位(价值高于 MC)没被生产——无谓损失。
Match each term to its meaning. · 把每个术语与它的含义配对。
Efficiency is MSB = MSC; missing it is a market failure with a deadweight loss. · 效率是 MSB = MSC;错过它就是有无谓损失的市场失灵。
A worked case
- The last cinema ticket is worth 9 to society (MSB) but costs only 5 to provide (MSC).
- Since $MSB > MSC$, society gains 4 from making it — so not selling it is inefficient.
- Efficiency comes only when output expands until the 9 falls and the 5 rises to meet.
- That meeting point is $MSB = MSC$.
一个例子
- 最后一张电影票对社会值 9(MSB),但提供它只花 5(MSC)。
- 因为 $MSB > MSC$,社会从生产它中获益 4——所以不卖它是无效率的。
- 只有当产量扩大,直到 9 下降、5 上升相遇时,才达到效率。
- 那个相遇点就是 $MSB = MSC$。
The last ticket is worth 9 to society (MSB) but costs 5 (MSC). Making it: · 最后一张票对社会值 9(MSB),但花 5(MSC)。生产它:
Since 9 > 5, society gains 4 from the ticket — not making it is inefficient. · 因为 9 > 5,社会从这张票获益 4——不生产它是无效率的。
A market is socially efficient at $MSB = MSC$, where total surplus is largest. Any other quantity leaves a deadweight loss. When a market can't reach that quantity alone — often from market power — it is a market failure, and a reason for the government to act.
市场在 $MSB = MSC$ 处社会有效,此时总剩余最大。任何其他数量都留下无谓损失。当市场无法独自达到那个数量——常因市场势力——就是市场失灵,也是政府出手的理由。