In APS, viability and survival are not the same thing.
Survival refers to an outcome: a system continues to exist.
Viability refers to an organisational condition: a system retains the capacity to maintain the conditions required for continued persistence.
This distinction matters because living systems are not static objects. They exist under conditions of continual change, material turnover, environmental variation, developmental transformation, and organisational disruption. Remaining alive at a particular moment does not necessarily mean that the conditions required for future persistence are being maintained.
A system may survive temporarily while losing viability. Organisational degradation, irreversible physiological decline, developmental failure, or ecological collapse may leave a system still present while progressively undermining its capacity for continued persistence.
Conversely, viability may require substantial change. Living systems often preserve continuity through repair, regulation, adaptation, reorganisation, and reconstruction. Viability is therefore not equivalent to stability. It is the capacity to preserve continuity through change.
The distinction can be summarised simply:
Survival asks: Is the system still here?
Viability asks: Does the system still possess the organisational capacity required for continued persistence?
Within APS, viability occupies a central position because it links biological activity to organised continuity. Agency maintains viability, and viability enables organised persistence. Understanding this distinction helps explain why living systems must do more than merely remain present: they must continually sustain the conditions that make future persistence possible.