In this paper, 'supranationalism' is being explored three-fold - as an idea (most commonly attributed to the 'European Project', i.e. historical process of european integration, from 1945. until today; also, conversely - as an ideology; and/or - as a phase of an overarching process(es) of 'communogenesis' ('globalisation' and 'civilization' or, following Nancy - 'mondialization') - conceptualised in the wider (meta-theoretical) philosophical and political framework of 'cosmocracy' or 'world (global) governance'. I'm starting the exploration of the implicated meanings and prospects for the future development of the world politics (taken as a whole), by examining firstly - the historical continuum of community's transformations (from 'the Western' perspective), as well as the neccessary transformations of it's central concept of 'sovereignty'; Secondly, I'm examining the substantiated framework for the theoretization of supranational phenomena via two major works in political philosophy - Immanuel Kant's Philosophical Essay on Eternal Peace and the Theory of Justice together with the Right of Nations by John Rawls (whose work is a direct continuation of Kant's opus). As a conclusion of the II. Part, I'm examining the idea and the theory of cosmocracy (or universal governance) in more detail, and then offering a working hypothesis of an 'emergent nature of the process as a whole, and of supranationalism as it's integral part or phase);Finally, I'm starting the examination of the supranational phenomena in practice - exclusevely in the context of the 'European Project' as a model to be followed in the future by others, and the EU as a central actor on the world stage, when contemporarily considering the possible realizations of the given theoretical presuppositions from the Part II. I'm conluding with the optimistic prospect of the European Union as a (historical) core of the future Global Community or World Federation, arbitrarily but significantly named - 'United Earth Republic'.