APS distinguishes between organisms, biological individuals, and biological agents while recognising that these concepts frequently overlap in living systems.
A biological individual is a unit of viability-oriented, constraint-closed organisation. Individuality concerns the integration of processes into a coherent regime of organised persistence.
An organism is a biologically integrated living system functioning as a coordinated whole. Organismality concerns the degree of organisational integration and coherence exhibited by a living system.
A biological agent is a system capable of viability-oriented regulation and modulation of activity. Agency concerns the active regulation of organisation relative to conditions affecting persistence.
In many familiar biological systems — such as bacterial cells, plants, and animals — all three coincide:
- the organism is an individual,
- the individual is an agent,
- and agency is enacted through organismal organisation.
However, the concepts are not identical.
Some systems may exhibit forms of agency without constituting fully integrated organisms. Some collectives may exhibit partial individuality while remaining organisationally distributed. Species and taxa, by contrast, are classificatory patterns rather than organisms, individuals, or agents because they do not actively sustain viability-oriented organisation themselves.
APS therefore treats:
- individuality as a question of organised persistence,
- organismality as a question of biological integration,
- and agency as a question of viability-oriented regulation.
The distinctions are analytical rather than absolute, but they help prevent explanatory confusion between organisation, classification, and activity.