Globalization is at the core of academic and public discussions today. As a fact it cannot be dismissed; instead, the task for political philosophy is to broaden its concept and to refine the questions about it, including the problem of its legitimacy and rationalization. In this paper, I explore David Hume’s metaphor of commerce -the privileged device towards civilization- as a powerful way of thinking the correlation between exchange and cosmopolitism. Trade is a communication metaphor whose asymptotes are universality, openmindedness, reciprocal recognition and hospitality towards the other. I focus on the main concepts of Hume’s political philosophy -the artifices of justice and politeness- and reconstruct both the establishment of conventions -vs. contracts- and of their moral approval. That reconstruction illustrates how trade, in its broadest scope, motivates the configuration of a civilized humanity, the aim of legitimate globalization.