Dialectic relationships exist between architecture and emergent architecturally informed disciplines. Interior design constitutes such a discipline and is considered a critical case study. The main problem is to investigate the ontology of interior design by considering its affiliation with architecture. With the use of Julia Kristeva’s construct, the abject, a synopsis of architectural and interior design theory is read to ascertain the dialectic and overlapping relationship. Through heuristic enquiry an ontological analysis of interior design (with reference to essentialist aspects of architecture) is made. The Manichean dialectic is employed to produce qualitative descriptions that portray the disciplines as discrete ‘others’. Architecture is a normative profession which considers interior design as a part of itself.