In APS, failure is not merely the absence of successful functioning. It is a revealing feature of viability-oriented organisation itself.
Living systems exist only through the ongoing maintenance of conditions required for their persistence. Because those conditions are vulnerable, malfunction, breakdown, and death become biologically meaningful. Failure therefore exposes what a system depends upon, how its organisation is maintained, where its regulatory limits lie, and whether persistence can be restored under perturbation.
Systems capable of repair, compensation, adaptive reorganisation, or recovery reveal forms of internally grounded organisation that are not present in merely stable physical systems. Their responses to disruption make visible the organisational capacities responsible for sustaining continuity.
This is why failure is diagnostically important in biology. Malfunction reveals persistence-sensitive function, breakdown reveals erosion of organisational coherence, and death reveals the collapse of viability-oriented persistence itself.
In APS, vulnerability is therefore not accidental to life. It is constitutive of the kind of organisation living systems are.
Key Point: Living systems reveal their organisational structure most clearly through vulnerability, repair, breakdown, and the ongoing possibility of failure.