Interdependence

Interdependence means that parts of a system depend on each other. Change in one part affects others; those effects can feed back. The system is a web of relationships, not a set of independent units. Interdependence is the norm in organisations, supply chains, markets, and ecosystems. The strategic implication: optimising one part in isolation can suboptimise or harm the whole. You need a view of how the parts connect — who depends on whom, and how changes propagate. Interdependence can be a source of resilience (redundancy, mutual support) or of fragility (cascade failure, unintended consequences). The discipline is mapping dependencies and anticipating knock-on effects before acting.

Interdependence varies in strength and sign. Strong interdependence means one part's state heavily influences another (e.g. single supplier, critical component). Weak interdependence means the link exists but is loose. Positive interdependence means one's gain helps the other (e.g. platform and complementor). Negative interdependence means one's gain can hurt the other (e.g. competitors). Mapping the sign and strength clarifies where leverage is and where risk concentrates. The mistake is treating the system as if parts were independent — making a change and being surprised when second- and third-order effects dominate.

The model appears in supply chain (supplier-customer interdependence), in platform businesses (platform-developer interdependence), and in teams (role interdependence). It also appears in competition (rivals are negatively interdependent) and in cooperation (allies are positively interdependent). Strategy that ignores interdependence misses both opportunities (aligning positive interdependence) and risks (cascades, unintended harm from negative interdependence).