Why is there complexity in engineering? A scoping review on complexity origins

Background: An alternative to the difficulty of defining complexity is to explore its origins. This promising way of dealing with complexity, however, is currently hindered by a major shortcoming. We currently have various perspectives, terms, contexts, complexity study objectives, etc. This impedes consensus and overview of the complexity origins within the systems engineering communityObjective: We explored this variety through a scoping review covering the variety in the complexity terms (RQ1), complexity classifications (RQ2), engineering contexts (RQ3), and complexity study objectives (RQ4).Design: Four online databases were used to identify papers published 2012-2022, from which we selected 72 publications. Included publications had the word "complexity" in their title and abstract and discussed its origins or classifications.Results: We mapped 42 terms referring to complexity origins. We found over 300 classes and subclasses of complexity, which we organized in 31 clusters. We identified 29 engineering contexts interested in complexity origins. Finally, we identified five complexity study objectives, and their mapping showed that less than half the screened papers (31) were concered with identification of complexity origins.Conclusions: While it might not be necessary (or even possible) to have one single term or one single classification, it is currently very difficult to work with the extremely large number of different terms, and classes. Future efforts should also focus on unification, clarification, and standardization of the terminology and the classifications of complexity origins, which can get us closer to reaping the benefits of the already existing contributions.