In modern philosophy the concept of antagonism is strictly related to the issue of anthropological roots of political conflict. Starting from Kant's definition of antagonism as "unsocial sociability", the paper claims that philosophical reflexions on antagonism set the issue in a quite different anthropological frame than the classical formulation by Hobbes which equated the human "state of nature" to the war of everyone against everyone. The sharp opposition between "state of nature" and "civil state" is replaced by an understanding of the structural ambivalence of human sociability, marked out by rivalry and identification and always hanging between cooperation and conflict, so that the main political task is not any longer intended as repressing human nature but as governing and steering it towards civilization. Contemporary theories of social antagonism rest on the same anthropological frame, although proceeding in very different and even opposite directions. Testing ground for comparing the different theoretical approaches should be their ability to explain the internal logic and the external dynamics of the imperfect communities populating the current global society.