APS uses several closely related concepts because different explanatory questions reveal different aspects of the same living organisation.
These concepts do not compete with one another, and APS is not repeatedly redefining life or agency. Instead, each concept highlights a different explanatory dimension of viability-oriented organisation.
| Question | APS Concept |
|---|---|
| What is at stake? | Viability-oriented organisation |
| What does the work? | Agency |
| What grounds the activity internally? | Constraint closure |
| How does persistence occur? | Process |
| How is activity coordinated? | Scale |
These are complementary explanatory perspectives rather than separate entities or layers.
For example:
- viability-oriented organisation identifies the organisational condition that must be maintained,
- agency identifies the system’s ongoing self-maintaining activity,
- constraint closure explains why this activity belongs to the system itself,
- process explains why persistence requires continuous activity through time,
- and scale explains how this organisation is coordinated across interacting spatial and temporal domains.
APS therefore examines the same underlying biological reality from several necessary explanatory perspectives rather than reducing life to a single defining property.