SYSTEM REVISITED – AGAIN.

This paper reviews the revised foundational definitions of system and systems engineering in the recently published (2023) fifth edition of the INCOSE Systems Engineering Handbook. The new INCOSE definitions derive from an earlier INCOSE Fellows' Initiative on System and Systems Engineering Definitions that began in 2016 and finally reported in 2019. After introducing the concept of system and reviewing the new definition, the paper concludes that the concept, not rooted in a single science or exemplar domain, is so pervasive as be a meta‐concept that does not have a dominant scientific definition. It proposes further work towards a more scientific definition of an engineered or artificial system – the primary interest of INCOSE – at a lower level of abstraction. While the authors define systems engineering functionally as a process or approach, we see the essence of systems engineering as abstraction. Using the more accepted metaphysical distinction between the real, virtual, and abstract, we define the output of systems engineering as an abstract (simplified symbolic) representation or model that is the basis for defining the real; firstly, the virtual representation of something not (yet) existing physically but made to appear so and, finally, the physical. Thus, we position systems engineering as the abstract phase within a three‐phase abstract‐virtual‐physical engineering design and realization process. [ABSTRACT FROM AUTHOR]