Discussion on the Paper “Is Complexity the Answer to the Continuum vs. Discontinuum Question in Rock Engineering?” by Erharter and Elmo in Rock Mech Rock Eng (2025)

Abstract In their recent contribution, Erharter and Elmo (Rock Mech Rock Eng, 2025) proposed to resolve the long-standing continuum vs. discontinuum question in rock engineering by characterising rock mass complexity. While their attempt to introduce quantitative metrics into this debate is commendable, their treatment tends to apply the concepts of complexity and emergence in ways that do not align with their established meanings. In this Discussion, I address these issues by providing several points of clarification, particularly concerning how the authors have positioned their work in relation to complexity science and to my earlier article (Lei, Rock Mech Bull, 2023).