美国华人买鱼为何便宜？

经济学家往往抽象地研究"市场"，但一些市场绝不是抽象的。在荷兰，阿斯米尔(Aalsmeer)鲜花市场每天会有2000万朵色彩艳丽的鲜花上市；而东京清晨的筑地鱼市(Tsukiji fish market)，其迷人程度足以与六本木(Roppongi)的夜店争夺游客的注意力。（筑地鱼市场游客区熏鼻的酒味说明，许多游客将这两种体验结合在一起，在这里通宵狂欢。）

Economists tend to study "the market" in the abstract, but some markets are anything but abstract. The Aalsmeer auctions in the Netherlands burst with the colour of more than 20 million flowers a day, while Tokyo's early-morning Tsukiji fish market (lovingly described on page 16) is enthralling enough to compete for tourist attention with the nightclubs of Roppongi. (The stink of alcohol in the tourist pens of Tsukiji suggests that many visitors have combined both experiences to make a night of it.)

除了游客之外，这些著名的市场也值得经济学家关注。很多经济学理论都有假设前提，不考虑市场交易实际如何进行。这是一件令人惋惜的事；斯坦福大学(Stanford)已故经济学家约翰o麦克米兰(John McMillan)认为，市场只有在设计完备的情况下才能运转良好。市场的全部理念在于使人们能够从交易中获利；设计糟糕的市场通常会失败。

These celebrated markets deserve attention from economists as well as tourists. A lot of economics assumes away the details of how market transactions actually work. That is a shame; the late John McMillan, an economist at Stanford, argued that markets will only work well if they are well designed. The whole idea of a market is to allow gains from trade to take place; a badly thought-out market will often fail.

即使对于像买鱼这样简单的交易，事情也并不像乍看上去那样简单。

There is more than meets the eye even to a simple transaction such as buying fish.

经济学家凯瑟琳o格雷迪(Kathryn Graddy)曾经花了一个月时间，追踪纽约富尔顿鱼市(Fulton Fish Market)中的一位鱼商。她大清早就要起床，而且要交保护费才能把车停到离市场较近的安全地点。她发现，鱼商似乎对不同种族的人要不同的价格--尤其明显的是，亚裔买家往往会拿到比白人更有利的价格。一个可能的解释是，亚裔买家在唐人街拥有对价格更加敏感的客户。

economist Kathryn Graddy once spent a month shadowing a trader at the Fulton Fish Market in New York, rousing herself in the early hours and paying protection money to park her car in a safe spot near the market. She discovered that market traders appeared to charge different prices to different ethnic groups - in particular, Asian buyers tended to win keener prices than white buyers. The likely explanation was that the Asian buyers had more price- sensitive customers in Chinatown.

尽管如此，这仍是一个令人惊讶的结果。

Still, this was a surprising result.

在一个竞争性市场，鱼商应该无法向白人客户要更高的价，而富尔顿鱼市理应是一个竞争性市场：它是全球第二大鱼市。（筑地鱼市场的规模是富尔顿鱼市的5倍多，完全不是一个级别）。格雷迪发现，即使在富尔顿鱼市，完全竞争也难觅踪迹。

A competitive market should eliminate the traders' ability to charge white customers more, and the Fulton Fish Market should be competitive: it is the world's second largest. (Tsukiji, more than five times larger, is in a league of its own.) Graddy discovered that even at Fulton, perfect competition was elusive.

然而，市场运转得越好，达成的交易就可能越多。我们或许想要压制交易，但一些交易如此诱人，以至于压制力有多大，抵抗力就有多大：无论学校商店是否有巧克力棒存货，学生都会弄到巧克力棒吃。在混乱的索马里首都摩加迪沙，私营商人想出了使电力市场在没有电表的情况下也能运转的方法：客户根据其家中或者商铺里的电灯泡数量付费。

Nevertheless, the better markets work, the more transactions they make possible. Some transactions are so tempting as to be irrepressible, much as we might want to repress them: school children will be supplied with chocolate bars whether or not the school shop stocks them. Other transactions are inspiring in their resilience. In the chaos of Mogadishu, Somalia, private merchants have worked out ways to get the market for electricity to work without metering; customers pay according to the number of bulbs in their home or workshop.

然而，许多交易需要的支持远多于此。现代交易基础设施包括法律体系、征信记录、签证和公司账户。举例来说，买股票看上去并不太复杂，但当你买股票时，你就等于将资金借给一家公司（例如说一家中国公司），换取与该公司分享未来盈利的权力。