EN
In the article the author analyses Jean-Luc Nancy's attempt to transform the traditional aim and structure of fundamental ontology or 'first philosophy'. By radicalising the Heideggerian motif of 'Mitsein', being-with, Nancy introduces irreducible plurality and diversity into the structure of ontological fundament as well as into the very expositional structure of ontology, which becomes a 'co-ontology' or a 'coexistential analytic of being-with'. He focuses on the issues of 'the singular plural' and 'origins' to reconstruct the process of this transformation of ontology and indicate its various consequences. One of them is that ontology of being-with can only exist in a transitional, ever-transforming way, in singularly plural forms of regional co-ontologies which are to be constantly re-shaped to take up the challenge eventfully posed by different spheres of coexistence.