Now more than ever, the resurgence of cosmopolitanism is necessary in the form of cosmopolitan, global ethics. Probably, this is the only way to face the contemporary crisis of planetary dimensions, both ecological and social, caused by accelerated techno-scientific expansion, violence and systematic war, and the looting and excessive exploitation of nature. To do this, it is essential to rethink the fundamentals and ethical implications of the idea of a political and legal world order, as Kant formulated at the end of the 18th century. However, cosmopolitanism of the 21st century must criticize and surmount the Eurocentric bias and hegemonic characteristics of the modern Western colonization of the world, and useglobal social movements that now represent a new alternative and critical cosmopolitanism.