The overall field of systems science is still in formation. - Len R. Troncale

Three unique and still timely aspects of Miller's text Living Systems were his citation of 173 specific ‘cross-level’ hypotheses, his unification of a vast number of phenomena from the biomedical sciences to the social sciences using a consistent taxonomy of seven hierarchical levels and 20 subsystems, and his consistent effort to make systems hypotheses more testable.

There is still insufficient integration of the many different strains of systems theory and systems tools.

We concluded then that it was more reasonable to expect a hierarchy of partial theories than to expect one overarching general theory.