Interdependence

It describes the continuous relationship between parts within a system: because no part exists in isolation, changes in one part alter the conditions for others, whether that influence is immediate or delayed. A policy change in one department of an organization can show up as a staffing shortage in a completely different department eight months later — the connection is real even when nothing in the moment points to it. This is not optional or conditional. It's a property of systems that cannot be removed, only ignored.

This tends to be underestimated because its effects are distributed rather than concentrated. Outcomes get attributed to local causes while the broader relationships that actually produced them go unexamined — which creates the appearance that parts are operating independently, even though they aren't. Recognizing the real pattern requires expanding the frame of observation past whatever happened immediately before the outcome you're explaining.

This is what makes coherence possible in the first place. Without it, alignment between parts wouldn't matter — there would be nothing at stake in how they relate. With it, every part's behavior contributes to the whole's stability or instability, whether or not that contribution was intended. It's the structural link between local behavior and system-wide outcome — the reason coherence and incoherence are properties of a system rather than a single part.