The point of departure for the sustainability debate is the definition of the World Commission on Environment and Development, which is, however, usually quoted incompletely. Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Evolving complex systems which, according to the system rules, consist of heterogeneous elements, and demonstrate heterogeneous patterns of existence and activity have a number of typical properties. The structure used in this paper, based on Allen, was chosen because it allows existing types of economics ontologies and models, as well as the economy itself, to be directly classified with reference to their respective degree of complexity. To date no theory exists which would allow the systematic analysis of the sustainability of evolving systems, at the system level. Sustainability differs from other social theories not through a different subject area, but due to its different perspective, and specific, non-negotiable basic values.