Joseph Norman and Yaneer Bar-Yam, Special operations forces: A global immune system?, in Unifying Themes in Complex Systems IX, A.J. Morales, C. Gershenson, D. Braha, A.A. Minai, Y. Bar-Yam, Eds. (Springer, July 23, 2018).
The use of special operations forces (SOF) in war fighting and peace keeping efforts has increased dramatically in recent decades. A scientific understanding of the reason for this increase would provide guidance as to the contexts in which SOF can be used to their best effect. Ashby's law of requisite variety provides a scientific framework for understanding and analyzing a system's ability to survive and prosper in the face of environmental challenges. We have developed a generalization of this law to extend the analysis to systems that must respond to disturbances at multiple scales. This analysis identifies a necessary tradeoff between scale and complexity in a multiscale control system. As with Ashby's law, the framework applies to the characterization of successful biological and social systems in the context of complex environmental challenges. Here we apply this multiscale framework to provide a control theoretic understanding of the historical and increasing need for SOF, as well as conventional military forces. We propose that the essential role distinction is in the separation between high complexity fine scale challenges as opposed to large scale challenges. This leads to a correspondence between the role SOF can best serve and that of the immune system in complex organisms--namely, the ability to respond to fine-grained, high-complexity disruptors and preserve tissue health. Much like a multicellular organism, human civilization is composed of a set of distinct and heterogeneous social tissues. Responding to disruption and restoring health in a system with highly diverse local social conditions is an essentially complex task. SOF have the potential to mitigate against harm without disrupting normal social tissue behavior. This analysis suggests how SOF might be leveraged to support global stability and mitigate against cascading crises.
Requisite Variety. Panel (a) shows a system (right) being exposed to environmental disturbances (left). The variety of the environment is greater than the variety of the system, as there are 4 unique disturbances but only 3 unique responses. The system lacks the ability to respond to the green hexagon, which will disrupt it. Panel (b) shows a similar case, but where the system variety matches the variety of potential disturbances—the system has the requisite variety to respond to all potential disturbances. Systems with variety greater than that of their environment also possess requisite variety.