Provisional conclusions about hierarchical organisation in complex systems

This panorama of hierarchical organisation in social and natural sciences was intended to improve our understanding of universally emerging hierarchical organisations in nature and society. We expected new insights from the analysis of the scope for circulating concepts and methods between various disciplines. We were searching for a possible general explanation for hierarchical structures. We have reviewed a whole set of quantitative and qualitative approaches, including measures and analytical tools, which provide deeper knowledge about general and specific processes generating or maintaining hierarchies. But this theoretical and methodological investigation has also led us to reverse the question, through the discovery of a possible explanatory power of hierarchical structures themselves, as a necessary part of the architecture of complex systems. Looking for hierarchical organisation would thus become an essential methodological step in the description and understanding of complex systems.