"I think that the way the world is organized today is fundamentally unjust. It’s like feudalism in important respects. In a world of relatively closed borders like ours, citizenship is an inherited status and a source of privilege. Being born a citizen of a rich country in North America or Europe is a lot like being born into the nobility in the Middle Ages. It greatly enhances one’s life prospects (even if there are lesser and greater nobles). And being born a citizen of a poor country in Asia or Africa is a lot like being born into the peasantry in the Middle Ages. It greatly limits one’s life chances (even if there are some rich peasants and a few gain access to the nobility). These advantages and disadvantages are intimately linked to the restrictions on mobility that are characteristic of the modern state system, although the deepest problem is the vast inequality between states that makes so many people want to move. This is not the natural order of things. It is a set of social arrangements that human beings have constructed and that they maintain."
(Joseph Carens, The New York Times: When Immigrants Lose Their Human Rights)