What tariffs would countries impose if they did not have to fear any retaliation? What would occur if there was a complete breakdown of trade policy cooperation? What would be the outcome if countries engaged in fully efficient trade negotiations? And what would happen to trade policy...

I build a simple dynamic model of the formation of an international social network of importers and exporters. Firms can only export into markets in which they have a contact. They acquire new contacts both at random, and via their network of existing contacts. This model explains (i) the...