APS framing
Biological processes are organised across different spatial and temporal extents. Molecular regulation, cellular dynamics, organismal activity, and ecological interaction may therefore become causally relevant to one another without constituting separate causal layers or a fixed hierarchy.
APS uses multi-scale causation where an explanandum requires causal relations across such scales to be made explicit. The term does not identify a separate kind of causation, nor does it imply that all biological causation is inherently multi-scale.
Cross-scale influence must be materially implemented. Processes and constraints organised across one spatial or temporal extent can alter the local conditions under which other biological processes occur. Wider-scale organisation does not supersede local causal processes; its causal relevance depends upon the material relations through which those local conditions are modified.
Biological organisation can therefore involve reciprocal and constraint-mediated relations across scales. Which scales are explanatorily relevant depends upon the phenomenon under investigation and the causal relations actually supported by the evidence.
No scale possesses intrinsic causal or explanatory priority. Nor does APS assume that an explanation spanning several scales is necessarily superior to one confined to a narrower domain. Multi-scale analysis is warranted where relations across scale contribute to explaining the particular phenomenon.
In brief
Multi-scale causation describes materially implemented causal relations across spatial or temporal scales where those relations are relevant to the biological phenomenon being explained.
Key Point
Cross-scale causal influence in APS must be materially implemented: processes and constraints organised across different scales can alter local causal conditions without wider scales superseding local causation.