The thing is, we still live with other human beings in geopolitical communities. Every such community--every formally organized community, for that matter--will necessarily have some organizing ethic. That ethic will determine the structure and (sanctioned) functioning of the inevitable, unavoidable political process (the process of effecting choices for the community as a whole). At the level of the nation-state, one unavoidable choice will be to decide what kind of economy (as inevitable as a political process) the community will have. For the organizing ethic in itself and its regulatory effects to be just does require universality because that is the only safeguard against arbitrariness. As Locke correctly saw, arbitrariness in interactions among human beings is injustice.