To facilitate the discussion, I would argue that the different schemes can be classified into two general categories. This concept, inspired by Keynesian and mercantilistic economics, consideres trade as an instrument in the toolbox of development policies that can be managed, in combination with centralized planning, to acquire the benefits of greater employment and a positive balance of payments. For this school of thought, trade is a zero- sum game. The failure of Keynesianism to deliver on its promise of prosperity and stability effectively opened the doors for the revival of free-market theories and more orthodox policies. In this environment, the rediscovery of the role of market forces has lead to a new way of looking at international trade.
Free trade enables an economy to be more efficient and productive.
International competition invites innovation and more effective allocation of resources. Wider and more open markets foster greater competitiveness among economies and among companies as well. And probably most importantly, the open flow of goods and services guarantees lower prices and a satisfied consumer. In the final analysis, trade is a positive-sum game for the followers of this theory. Pursuant to this set of beliefs, a different approach to integration emerged.