The lack of a recognized theoretical disciplinary base for the built environment has been noted on a
number of occasions. The field holds the promise of being interdisciplinary, but requires the development
of a common epistemological construct. It has been proposed that a unified theory of the built
environment may require that the built environment be understood as a complex social–ecological system.
It will argued, however, that the challenge is more fundamental; that development of an adequate
model would require convergence of the ideas of interdisciplinarity and complexity, with concomitant
epistemological as well as ontological considerations. The application of whole-system theory to the
built environment is explored with special reference to the identification of boundaries and modularities
in different domains and the implications for a taxonomy of the built environment. The development
of a theoretical base for the field as a whole would facilitate axiological decision-making in the built
environment and also inform both curriculum design and research strategy in the subject area.