Martin Wolf We are living in a dividing world. These divisions have many ramifications. But not the least important of these are for global commerce. The slowdown in world trade, the shift towards economic nationalism and the growing demands in the west, and especially in the US, for decoupling from China are reshaping the global economy. It is, as yet, unclear how far this decoupling will go. It is unclear how far the inward-looking interventionism will go either. But there...