Discussion on “Is Complexity the Answer to the Continuum vs. Discontinuum Question in Rock Engineering?” [Erharter and Elmo 2025]

Abstract This discussion critiques Erharter and Elmo (2025)’s proposal to use complexity as a criterion for selecting continuum versus discontinuum modelling approaches in rock engineering. We argue that the article lacks definitions of continuum and discontinuum behaviour as well as emergence. It does not provide any measure or method to connect the complexity parameters, which Erharter and Elmo (2025) claim arise from emergence, with rock mass behaviour. Finally, through counterexamples, we demonstrate that their approach fails to suggest the correct type of modelling approach, whether continuum or discontinuum.