Conventional framing

Biological causation is often described in terms of interactions occurring at specific “levels of organisation,” such as molecular, cellular, organismal, or ecological. Explanations frequently privilege one level—most commonly the molecular or genetic—as the primary site of causation, with higher-level phenomena treated as derivative or emergent.

This approach can be useful for analysis, but it risks fragmenting biological explanation by treating causation as localised within discrete layers of organisation.

APS reframing

Multi-scale causation does not introduce a separate kind of causation, but specifies how causation—understood as organisation-dependent relations among processes—operates in biological systems.

APS rejects the idea that causal relations are confined to or originate from discrete levels. Instead, causation is inherently multi-scale: it arises through the coordinated coupling of processes across spatial and temporal extent.

Biological organisation is continuous and integrated. Processes at different scales—molecular regulation, cellular dynamics, organismal activity, and ecological interaction—are not independent layers but interacting aspects of a single viability-oriented system.

Causal relations therefore arise through the organisation of processes across scales, not within isolated levels. This organisation is maintained through constraint-based coupling, in which processes both depend on and contribute to the conditions that sustain the system’s persistence.

Causation therefore operates through:

  • Reciprocity — processes at different scales influence one another
  • Coupling — interactions are structured through constraint-closed organisation
  • Propagation — effects spread across scales through coordinated activity

No single scale has intrinsic causal priority. What appears as “bottom-up” or “top-down” causation reflects different perspectives on the same underlying organisation.

Multi-scale causation is thus not an addition to mechanistic explanation but a clarification of how causation operates in living systems: as distributed, integrated, and continuously coordinated across scales.

In brief

Multi-scale causation describes how causation in biological systems operates through the coordinated interaction of processes across scales, rather than within discrete levels.

Key Point

Causation in biology is not level-bound but scale-coupled—arising from the reciprocal interaction of processes within an integrated, viability-oriented organisation.