A-level经济 | Trade bloc 详解！
Trade bloc是历年考察的一个小点，不会占很大的分值，但是时常在选择题中出现，同学们在international trade的学习过程中也时常忽略trade bloc们。
今天，把重要的几个trade bloc跟大家好好说道说道。
各种bloc 的概念如下：
Atrading blocis a group of countries that have agreed to reduce tariff and other barriers to trade for the purpose of encouraging free or freer trade and co operation between them. Beginning with the lowest degree of economic integration, we can distinguish between the following trading blocs.
Afree trade areaconsists of a group of countries that agree to gradually eliminate trade barriers between themselves, and is the most common type of trading bloc.
Acustoms union consists of a group of countries that fulfils the requirements of a free trade area (elimination of trade barriers between members) and inaddition adopts a common policy towards all non-member countries.
Acommon marketis an even higher degree of economic integration, in which countries that have formed a customs union proceed further to eliminate any remaining barriers to trade between them.Theycontinue to have a common external policy (as in a customs union), and in addition, they agree to eliminate all restrictions on movements of any factors of production within the common market.
AMonetary unioninvolves a far greater degree of integration than a common market, and occurs when the member countries of a common market adopt a common currency and a common central bank responsible for monetary policy.
Aeconomic unionis a trade bloc where there is free trade between member countries, a common external tariff and some common economic policies, which may include a common currency.
为了让大家更加清楚blocs的进阶关系，我们做出以下演变图，可以简单认为free trade area为最基础的bloc形式，而FTA成员国之间可能在贸易保护方面取消或减少关税，进而在factor market上面实现free movement，所以内部深化形成common market；FTA也有可能在内部取消关税等基础上实现对外统一的关税政策，因此便形成了custom union；
可是common market没有对成员国以外国家的统一政策，此时，如果在common market的基础上实现统一关税，也就形成了economic union；
而如果在custom union的基础上实现factor free movement则形成economic union；不过通常economic union会存在fiscal union。
最后，关于monetary union，其实最简单的monetary union就是使用统一的货币，但是我们又认为monetary union需要建立在一定的基础上，所以理论上我们会认为monetary union在economic union内部实行，以EU与EMU为例：
