A New Grounding for ( M,R ) Systems

Abstract

Rosen’s metabolism–repair (M,R) systems have been debated for decades, yet their formal nature and crucially their physical realization remain unclear. Here we revisit the “grounding” problem and argues that many difficulties stem from overly literal identifications of Rosen’s sets and mappings with a specific subclass of biochemical entities (e.g., enzymes and substrates), which introduce arbitrariness and obscure the role of non-synthetic cellular processes. We propose three interpretational changes. First, we replace molecules-as-primitives with reactive–structure units (RS units): physical building blocks that inseparably combine reactivity (capacity for chemical participation) and structure/bulk (spatial extension). In this view, the material domains of Rosen’s model (the A and B of his famous diagram) are configurations of RS units rather than curated lists of biochemical species. Second, we broaden the meaning of processes in (M,R) models beyond molecular transformations, accommodating mesoscale and physical phenomena (e.g., cytoskeletal dynamics, trafficking, secretion, macro-molecular interactions) that are essential for living organization. Third, we absorb all biosynthetic activity into the mapping f : A → B, leaving other mappings to capture higher-order, non-biosynthetic functionalities that enable persistence indirectly (e.g., homeostasis, defense, context management). Overall, the reformulation shifts the emphasis from narrow self-synthesis to persistence: circular self-production supported by diverse ancillary processes, opening conceptual space for clearer groundings and for future formal development (e.g., via applied category theory).