The growing human mobility is having a direct impact on a political category that has been usually taken for granted in democratic liberal theories: the category of border. Political Theory has not paid enough attention to the concept of ‘border’. This “silence” becomes highly relevant, since it is by discussing the issue of borders that one can detect most of the incoherencies of the Liberal Political Theory. It is also surprising to see that the notion is a taken-for-granted concept in the current debates on immigration. Based on these premises, the goal of this article is to discuss the grounds for a Political Theory on Borders (PTB). As a first step, I identify those analytical distinctions that allow us to provide a solid base for thi...