Scale should not be confused with hierarchy.
A hierarchy implies ranked levels, explanatory priority, or one-way relations of control. APS treats such language as an explanatory convenience rather than as a literal description of biological reality.
In APS, scale refers to the different spatial, temporal, and organisational contexts within which biological processes occur. Molecules, cells, tissues, organisms, populations, ecosystems, evolutionary lineages, and societies are not separate layers stacked above one another. They are interconnected domains of organised persistence.
Different scales reveal different continuity problems, different forms of coupling, and different aspects of viability-oriented organisation. No scale is automatically more fundamental simply because it is smaller, and no scale is more important simply because it is larger.
APS also distinguishes scale from resolution. Scale concerns the organisation of biological activity itself. Resolution concerns the granularity at which that activity is described or analysed. What appear to be “levels” often reflect differences in explanatory resolution rather than discrete ontological layers.
Biological explanation therefore requires movement across scales rather than reduction to a single privileged level. Continuity is sustained through reciprocal relations linking physiological, developmental, ecological, evolutionary, and social processes.
Key Point. Scale is not a hierarchy of separate levels of reality. It is an explanatory perspective for understanding organised persistence across interconnected domains of biological organisation.