There can be little doubt that, historically, trade has acted as an important engine ofgrowth for countries at different stages of development, not only by contributing to a moreefficient allocation of resources within countries, but also by transmitting growth from onepart of the world to another. There are static and dynamic gains to be had from tradebetween countries but there is nothing in the theory of trade that says that the gains areequitably distributed. Also, there is nothing in the theory of Customs Unions that says thatthe gains from trade will be equitably distributed between members. Indeed, the CustomsUnion as a whole may be welfare-reducing if trade diversion exceeds trade creation. Recentresearch suggests that regional trade agreements, reduce growth and investment, butgeneralised trade liberalisation in the form of unilateral tariff reductions (or the reduction ofnon-tariff barriers to trade) improves growth performance. Export growth relax the balanceof payments constraint on demand by providing the foreign exchange to pay for the importcontent of higher levels of consumption, investment and government expenditure. Mostdeveloping countries are constrained in their growth performance by a shortage of foreignexchange and could therefore grow faster with more exports.

毫无疑问，在历史上，贸易一直是处于不同发展阶段的国家增长的重要引擎，它不仅有助于在国家内部更有效地分配资源，而且还将增长从世界的一个地区转移到另一个地区。国与国之间的贸易既有静态的也有动态的收益，但贸易理论中并没有说收益是公平分配的。此外，在关税联盟的理论中，也没有任何说法说贸易收益将在成员之间得到公平分配。事实上，如果贸易转移超过了贸易创造，关税联盟作为一个整体可能会减少福利。最近的研究表明，区域贸易协定会降低增长和投资，但单边降低关税(或减少非关税贸易壁垒)形式的全面贸易自由化会提高增长绩效。出口增长为更高水平的消费、投资和政府支出提供外汇，从而放松了对需求的收支平衡约束。大多数发展中国家的增长业绩受到外汇短缺的限制，因此出口增加可以增长得更快。