In APS, viability and survival are not the same thing.
Survival describes an outcome: a system continues to exist.
Viability concerns the organisational conditions under which a living system can continue functioning as the organisation it is. It therefore refers not merely to continued presence, but to the capacity to maintain and re-establish conditions compatible with continued functioning.
This distinction matters because living systems are not static objects. They undergo continual material turnover, environmental variation, developmental transformation, perturbation, and organisational change. Remaining alive at a particular moment does not necessarily mean that the conditions required for continued functioning are being successfully maintained.
A system may therefore survive temporarily while its viability deteriorates. Organisational degradation, irreversible physiological decline, developmental failure, or deterioration of organism–environment relations may leave a system still present while progressively undermining the conditions required for its continued functioning.
Conversely, maintaining viability may require substantial change. Living systems can preserve continuity through regulation, repair, adaptation, reorganisation, and reconstruction. Viability is therefore not equivalent to stability: the relevant organisation may persist precisely because it changes in ways that maintain or re-establish viable conditions.
The distinction can be summarised simply:
Survival asks: Is the system still here?
Viability asks: Are the organisational conditions required for its continued functioning being maintained or capable of being re-established?
Within APS, viability identifies the system-relative conditions in relation to which biological activity can support or undermine continued functioning. Biological agency is viability-oriented organisational activity, while organised persistence concerns the continuity of living organisation through change. These are analytically distinguishable aspects of one living organisation rather than successive stages through which biological activity is converted into persistence.