a core ontological assumption [is that] each system of meaning or each symbolic order is essentially incomplete or lacking. While meaning is holistic, in the sense that the identity of an element depends on its relationship to other elements within a wider social structure, each structure is never closed. Each structure is marked by an impossibility — what Lacan captures with the register of ‘the real’ — which prevents the full constitution of meaning.
… in keeping with our ontological presuppositions every subject is a discursive construct or entity, whose identity depends on its relationship to other subjects and objects. However, because each discursive construct is never fully constituted, but essentially incomplete or lacking, the subject is also lacking and incomplete (127).