担心我提问的不够清楚，把原文也放上来：－）

Welfare in a monopolized market, like all markets, includes the welfare of both
consumers and producers. Whenever a consumer pays an extra dollar to a producer
because of a monopoly price, the consumer is worse off by a dollar, and the producer
is better off by the same amount. This transfer from the consumers of the good to the
owners of the monopoly does not affect the market’s total surplus—the sum of con-
sumer and producer surplus. In other words, the monopoly profit itself does not
represent a shrinkage in the size of the economic pie; it merely represents a bigger
slice for producers and a smaller slice for consumers. Unless consumers are for some
reason more deserving than producers—a judgment that goes beyond the realm of
economic efficiency—the monopoly profit is not a social problem.


The problem in a monopolized market arises because the firm produces and
sells a quantity of output below the level that maximizes total surplus. The dead-
weight loss measures how much the economic pie shrinks as a result. This ineffi-
ciency is connected to the monopoly’s high price: Consumers buy fewer units
when the firm raises its price above marginal cost. But keep in mind that the profit
earned on the units that continue to be sold is not the problem. The problem stems
from the inefficiently low quantity of output. Put differently, if the high monopoly
price did not discourage some consumers from buying the good, it would raise
producer surplus by exactly the amount it reduced consumer surplus, leaving to-
tal surplus the same as could be achieved by a benevolent social planner.

[em04]

ps是确实存在的，可以表示为profit,but cs只是consumer的一种主观感受。垄断相对于竞争来说，提高了价格，增加了利润，但是增加的利润小于消费者减少的CS，所以肯定存在deadweight loss

我刚才看到一个类似的问题，在本版yjhjerry所提

“Mankiw  PRINCIPALS OF ECONOMICS   326页的一句原话:

if the high monopoly price did not discourage some consumers from buying the good, it would raise producer surplus by exactly the amount it reduced consumer surplus,leaving total surplus the same as could be achieved by benevolent social planner.

这句话该怎么理解,我怎么感觉悟不对呀.我理解是如果producer surplus raised  和consumer surplus reduced都一样了,哪deadweight loss 哪儿来啊?”

我想，这与楼主所提问题本质上应该是一样的

我提出了一个解释以供商榷

“我们可借用税收的情况进行分析

与竞争均衡相比，提高价格、均衡数量减少实际上造成生产者剩余和消费者剩余都减少

减少的部分又可分为两块：税收收入与无谓损失

楼主问题中所谓“生产者剩余的增加量”应当就等价于税收收入，如果这一块与消费者剩余减少数量相等，那么，无谓损失应等于真正的生产者剩余损失”

画图的话，可以很明白地显示“无谓损失”

https://bbs.pinggu.org/thread-337273-1-1.html&replyID=29863&skin=1

    请问，为什么不用平均总成本曲线表示垄断企业的成本,它能比边际成本曲线更完整地表示企业发生的全部成本。