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时间和水平有限，虽然在编写的质量上严格要求、严格把关，但是在内容的编排上仍可能有不当之处，欢迎读者指正。张朝鹏2014年2月Chapter1Theoretical Foundations of Ecological City1.1 Ecological Economics1.1.1 Market Failures
Economists believe that a market system can generate efficient and the best outcome.But there are several assumptions underlie this belief：（i）Each person’s welfare depends only upon the goods that he consumes，and each firm’s profits depend only upon its own use of the factors of production.（ii）There are established and enforceable property rights over every good.（iii）There is a market for every good.（iv）Firms behave competitively，and in particular，believe that their own actions have no appreciable effect on market prices.（v）Participation in markets is costless.（vi）All market participants have the same information about the nature of the good and the circumstances under which it is traded.
If one or more of these assumptions does not hold，the market system does not give rise to an efficient outcome.These inefficient outcomes are called market failures.
188.8.131.52 Public Goods
A public good is one whose consumption benefits more than one person or firm.Some of these goods are non-rivalrous，in the sense that providing the good to one person necessarily allows the good to be provided to every other person at no additional cost.The lighthouse is one of these goods.If its warning beacon can be seen by one boat，it can be seen by every boat.The lighthouse’s successor，the global positioning system（GPS），also has this property.The signals of the GPS satellites are beamed to the earth，and if they are available to one person，they can be made available costlessly to every other person.Other goods are only partially non-rivalrous，in the sense that the quality of the benefit provided to each person diminishes as the number of the people to whom it is provided rises.These goods are said to be congestible，and are much more common than non-rivalrous goods.Examples of congestible goods include parks and recreational facilities，police and fire protection，and roads and bridges.Every public good involves a violation of assumption（i）.
Some public goods also have the property that，if they are provided to one person，they are automatically made available to everyone.Such goods are said to be non-excludable.The lighthouse is one example of a non-excludable public good.The GPS，by contrast，is not in principle non-excludable.Its signals could be sent in code，and the provider of the system could sell decoding devices to the manufacturers of GPS receivers.The provider would then be able to limit the number of users by limiting the number of decoders sold.The provider of the GPS（the U.S.defense establishment）has not chosen to do so，and hence the GPS is in practice non-excludable.
A pure public good is both non-rivalrous and non-excludable，and hence violates assumptions（i）and（ii）.Competitive firms are unable to provide sufficient quantities of these goods.Non-excludability means that the firms are unable to set a fee for the use of the public goods that they provide，and hence can only cover their costs if the users make voluntary payments.This situation gives rise to the free rider problem.Each user is confronted with the following choice：he can contribute to the provision of the public good and enjoy its benefits，or he can keep his money in his pockets and enjoy its benefits anyway.Not surprisingly，people faced with this choice prove to be reluctant to part with their money.Total contributions are relatively small，so only a small quantity of the public good is ultimately provided.Every person would be better off if everyone could be forced to give a little more.Governments，when they finance the provision of public goods through taxes，are therefore engaging in a socially beneficial form of coercion.
While the under-provision of public goods takes its most dramatic form when the public good is “pure”，the provision of less-than-pure public goods is also problematic.If a good is non-rivalrous but excludable，a private provider of that good can only remain in business by charging the users a positive price.This practice results in the exclusion of some potential users.The provider’s interests are at odds with those of society，because society’s welfare is maximized by excluding no one.If the good is congestible and excludable，by contrast，society’s welfare is maximized by excluding some users from each facility.Decisions about exclusions and the facility size must then be made simultaneously.
An externality can occur when a person’s utility is affected by another person’s consumption or by a firm’s production activities.As well，an externality can occur when a firm’s profits are affected by another firm’s production activities or by an individual’s consumption.However，not all such interactions constitute externalities.An externality only occurs when appropriate monetary compensation is not made.Appropriate compensation induces the generator of the externality to take into account-the effects of his actions on others，so that he curtails harmful activities and extends beneficial ones.
You are harmed if your neighbor throws noisy parties that prevent you from sleeping.Your neighbor is not required to compensate you for the harm done to you，so he doesn’t take your interests into account-the parties are long and loud.An externality is present here.
The small stores at a shopping mall benefit from the presence of a large department store.The department store draws customers to the mall，creating additional business for the small stores.The leases signed by the stores reflect this benefit：the department store often pays no rent，and the small stores pay higher rent than they would pay in the absence of the department store.This arrangement shifts the burden of rent from the department store to the small stores，so that the department store implicitly receives compensation.No externality occurs.
Although externalities can occur only if assumption（i）is violated，violations of some of the other assumptions can also be important.
Coase has emphasized the importance of clearly-defined property rights in determining appropriate compensation.Suppose，for example，that two farmers are drawing water from the same river.If the up-river farmer increases his water consumption by so much that the down-river farmer cannot obtain sufficient water for his needs，who should pay whom？If the up-river farmer has the right to draw as much water as he likes，the down-river farmer must bribe the up-river farmer to induce him to take less water.If the down-river farmer has the right to sufficient water，the up-river farmer must compensate him for his loss.But if the property rights are not clearly established（i.e.，if the farmers cannot agree as to whose rights have been violated），compensation is unlikely to be paid and an externality is likely to occur.
Compensation will not necessarily be paid even when property rights are clearly established.Suppose that a firm pollutes the air，to the detriment of（resulting in harm to） everyone living downwind.Suppose also that the firm has the property rights.An externality is prevented only if people band together to bribe the firm to reduce its emissions；but if the harm done to each person is small relative to the individual cost of negotiating the bribe，no one will bother to negotiate.Compensation will not be paid and an externality will occur.Thus violations of assumptions（ii）and（v）can also play a role in externalities.
Another interpretation of externalities is that they occur because some markets are missing.A steel producer knows the market price of steel，so he can evaluate the reward for additional production.He also knows the market prices of labor，iron ore，and fuel，so he knows some of the costs of additional production.He increases production if the reward exceeds the sum of these costs.However，one of the costs of additional production is a decline in air purity.Since there is no market for air purity，the firm is not forced to bear the cost of degrading the atmosphere，and does not include this cost in its profit calculation.Under this interpretation of events，an externality occurs in part because assumption（iii）is violated.While most non-economists would regard this view of pollution as exceedingly baroque，some economists believe that it is a useful way to analyze the problem.They argue that externalities can be eliminated by constructing artificial markets in which emissions permits-entitlements to pollute-are traded.
Some externalities，such as the noisy party and the polluting firm，are easily recognised.Other externalities are less readily recognised.Two important examples of well-disguised externalities are common property exploitation and co-ordination failure.
Common Property Resources
A common property resource is a good which is not owned by anyone.Individuals acquire ownership of a common property resource simply by taking it.Self-interested individuals are likely to take as much as they can and as quickly as they can.Early photographs of the Oklahoma oil fields show a virtual forest of oil derricks erected by competitors attempting to gain a greater share of the oil.The “land rush” depicted in so many Hollywood westerns is another example of this kind of behavior.
In the case of renewable common property resources，the rush to be first can lead to the exhaustion of the resource.Many fisheries have been commercially depleted，and others are threatened with depletion.The commercial values of the whale，the rhinoceros，the elephant，and the sea turtle are great enough to threaten these species with extinction.
Co-ordination failures are a particular form of externality，and therefore involve a violation of assumption1.They are treated here as a separate phenomenon only because they have some distinctive and interesting features.
In an efficient market economy，market prices convey everything that each economic agent needs to know about every other economic agent.Consider，for example，the markets for consumer goods.Each consumer believes that he can buy at the prevailing price as much of each goods as he likes and this belief is validated by the fact that he can，in fact，buy exactly the goods that he wants.Each firm believes that it can sell at the prevailing price as many units of goods as it wants，and is in fact able to do so.The transactions that consumers and firms want to make depend only upon prices，and they are able to carry them out.
Keynesian economics argues that this picture of the workings of the market economy is deficient.The quantity of goods that consumers want to buy is determined by their income，which is in turn determined by the quantity of labor that they can sell.Similarly，the quantity of labor that firms buy is determined by the quantity of goods that they can sell.A recession，the Keynesians argue，is a situation in which consumers do not buy goods because they cannot sell labor，and firms do not buy labor because they cannot sell goods.If this view is correct，each agent’s behavior is influenced by quantities as well as prices.
Similarly，an agent’s decision to trade in a market might be influenced by estimate of the probability that other agents will trade in that market.Multiple equilibriums are then possible.There could be an equilibrium in which few people trade because few people are expected to trade，and another in which many people trade because many people are expected to trade.Since trading is mutually beneficial，welfare is higher when more people trade.
184.108.40.206 Imperfect Competition
A competitive firm expands its production until the price of the last unit of output is just equal to the market price of the resources needed to produce that unit.If the other firms in the economy are also competitive，the market price of the resources is just equal to the market value of the other goods that could have been produced with the same resources.In these circumstances，consumers learn about their options by examining prices.If a good’s price is high，they are warned that consumption of this good requires them to forgo other goods that they themselves believe to be valuable.If good’s price is low，the consumption of this good requires them to forgo something，but not something of any great value.Consumers use these signals to decide which goods they should consume；specifically，they consume expensive goods sparingly and cheap goods freely.This mechanism-Adam Smith’s “invisible hand”-causes the economy’s limited resources to be allocated to the production of the goods that consumers most want.
This mechanism tends to break down if some firms are large enough to appreciably affect the prices at which goods are bought and sold.The most extreme case is monopoly，in which there is only one seller of a particular good.The price set by the monopolist is greater than the good’s marginal cost of production（i.e.，greater than the value of the goods that must be given up to production）.Consumers respond by buying fewer units of the good than they would if its price reflected its marginal cost of production.
Perfect competition is the only form of market organization under which a good’s price is certain to be equal to its marginal cost.Hence，any violation of assumption（iv）is likely to cause the free market outcome to diverge from the competitive outcome.
Arguably，imperfect competition is a symptom rather than a cause.The presence of imperfect competition suggests that something has prevented sustained competition among firms.One possibility is that production is characterized by increasing returns to scale，meaning that output more than able to produce and sell goods more cheaply than its competitors，and will eventually drive them out of business.Once it is alone in the market，it will behave as all monopolies do，restricting its output and raising its selling price.A second possibility is that entry into the industry involves such high set-up costs that potential competitors are unable to raise the necessary financial capital.Finally，it might be that a necessary patent is possessed by only one firm，ensuring its position as a monopolist.
220.127.116.11 Asymmetric Information
The price system is an important mechanism because it is decentralized，that is，because every economic decision is made by the people or firms directly affected by that decision.Each farmer knows which crops grow best on his own land，and he decides which crops will be grown there.Each firm knows which goods can be produced at its manufacturing plants，and the various ways in which these goods can be produced，and it makes decisions on exactly these issues.Each consumer knows his own tastes better than anyone else，and decides which goods and services he will purchase.All parties base their own actions on their own information and their knowledge of market prices.Consequently，they do not need to communicate detailed information about tastes and production processes to each other.
The value of the price system lies precisely in its ability to exploit information that is not widely known，but it can only do so if two essential kinds of information are known to everyone.
First，the market participants must be equally well informed about the nature of the good being traded.The purchase of a new computer，for example，would be a relatively simple matter if computers could be completely described by a small number of characteristics，say，processor speed and disc capacity.Computers with a particular speed and capacity would then differ in price only because their manufacturers were more or less efficient.A manufacturer which managed its inventory better，or more conscientiously sought out better deals on components，could offer its product at a lower price.Everyone would buy from this manufacturer，and the less efficient manufacturers would ultimately be driven from the market.The price system would work as it should.However，not all of the characteristics of computers are readily observable，and hence price differences are not easily understood.An inefficient producer might match the low prices of his more efficient competitors by substituting lower quality components for higher quality components.If consumers were unable to discover the difference between these products，the less efficient producers would not be driven from the market.
Second，the market participants must be equally well informed about the circumstances under which the good is traded.Here are two situations that satisfy this condition：
•We meet on a rainy day，and you have an umbrella while I do not.I might offer to buy your umbrella，and after some haggling，you might agree to sell it.This trade would be mutually advantageous，in the sense that each of us would place a higher value on the thing received than on the thing given up.Both of us know the circumstances of the trade（specifically，that the person without the umbrella will get wet），and our haggling establishes that my aversion to getting wet is greater than yours.
•It is not raining when we meet，but the clouds look threatening.Neither of us is certain that an umbrella will be needed，but we are looking at the same grey skies，so we are equally well informed about that possibility，any trade that occurs between us will again be mutually advantageous.
There are many situations in which the participants are not equally well informed，and the market outcome in these situations might not be efficient.Trades which are mutually advantageous might not take place，and trades that take place might not be mutually advantageous.Suppose that you have a toothache.You go the dentist believing that you need minor dental work，but the dentist instead suggests some major（and expensive）reconstruction.How do you know that this work actually needs to be done？How do you know that he is not simply creating a little extra business for himself？If you agree to the work，and if the work is largely unnecessary，the trade between you and your dentist is not mutually beneficial.If you are suspicious of his motives and refuse his advices，and the work is necessary，a trade which would be mutually beneficial dose not takes place.Similar situations arise when you deal with doctors，lawyers，stock brokers，and garage mechanics.They have better information than you do，but you might be uncertain as to whether they are advancing your interests or their own.1.1.2 Two Theorems and the Role of the Government
In this section，two theorems as well as their usefulness，and the role of the government will be introduced.
18.104.22.168 Two Theorems
Every economy must address three problems：Which goods are to be produced？How should they be produced？Who gets the goods once they have been produced？One way of solving these problems is to allow people to trade in competitive markets.The two fundamental theorems of welfare economics show that this solution is potentially a very good one.
The first theorem demonstrates that，under certain well-specified conditions，there is no better solution than the one generated by competitive markets.Specifically，any alternative solution that makes someone in the economy better off must also make someone else worse off.The reasoning behind this argument is simple.A system of competitive markets ensures that all mutually beneficial trades take place，so that every remaining trade-every adjustment of the solution-benefits one person only at another’s expense.
If a solution has property that any other solution can only make someone better off at someone else’s expense，it is said to be Pareto optimal.Arguably，we would not wish to accept a solution better off without harming anyone else，and we would certainly prefer this alternative to the original solution.However，the observation that a particular solution is Pareto optimal doesn’t mean that we need not consider alternatives.
There are many Pareto optimal solutions，and by definition，a move from one to another changes the distribution of economic well-being.If A and B are Pareto optimal solutions，and a move from A to B