In APS, scale does not simply mean size.
Biological discussions often use scale to distinguish between larger and smaller entities, such as cells, organisms, populations, or ecosystems. Such distinctions can be descriptively useful, but physical size alone does not determine the spatial or temporal extent relevant to a biological explanation.
In APS, Scale is the analytic projection concerned with where persistence is organised across spatial and temporal extents. It therefore concerns an explanatory question rather than a classification of biological entities by size.
The relevant extent depends on the explanandum. Molecular repair, physiological regulation, behavioural adjustment, development, inheritance, and evolution involve materially realised processes and relations with different spatial and temporal extents. An explanation should include wider or additional extents only where those relations make an explanatory difference to the biological target.
Two processes may occur within the same physical structure while differing substantially in their temporal extent. Conversely, materially related processes distributed over different spatial extents may be relevant to explaining the persistence of the same organised system. Neither case implies that scales themselves coordinate or integrate biological activity.
Scale therefore does not identify a hierarchy of biological levels, nor does it imply that living organisation must always be explained across multiple scales. It asks where the persistence relevant to a particular explanandum is organised across space and time.
Key Point. Scale is not a measure of size or a biological domain. In APS, Scale is the analytic projection concerned with where persistence is organised across spatial and temporal extents.