Systems: Principles vs. Rules

Systems engineering has always been concerned with the development of complex systems. Today’s complexity is reflected in our interest in new classes of systems such as systems-of-systems, socio-technical systems and enterprises, which can display characteristics associated with complex adaptive systems. One such characteristic is the uncertainty that comes in part from the large number of potential interactions that can exist within the system and between the system and its reference environment. Uncertainty is especially a concern in the foundational activity of requirements engineering where the primary objective is to provide an unambiguous basis for developing and evaluating solutions. It has been suggested that obtaining specific, desirable outcomes from the systems engineering process will not be possible for complex adaptive systems. Instead, our efforts should focus on guiding an evolving system towards acceptable “outcome spaces”. This paper extends this argument to the development of requirements for complex adaptive systems. First, it presents a discussion on the scalability of the structures used to organize and relate requirements that are traditionally rules-oriented, i.e. that prescribe specific actions or outcomes. It then explores the concept of principles-based requirements as a means to guide the evolutionary development of complex adaptive systems. Related research and potential research questions are also included