Three-Party Coalition Stability
Three-party coalitions need equal interdependence - any two-party sub-coalition viability creates instability.
Coalitions of two are unstable. Coalitions of three can be stable but require careful balance. The geometry matters.
Two-member coalitions: Member A + Member B vs. Everyone else. Problem: A and B are permanent rivals for top position within coalition. Stability: Low (37% last >2 years in chimp troops). Failure mode: Stronger member eventually abandons weaker.
Three-member coalitions: Member A + B + C. Problem: Any two can overthrow the third. Stability: Higher (68% last >2 years) if balanced. Failure mode: Weakest member gets ejected, returns to two-member instability.
The balance requirement for three-member stability: Coalition is stable when no two-member sub-coalition can gain more by excluding the third. Observed coalition collapse patterns (Bayesian analysis of 73 chimp coalitions): Benefit distribution Gini coefficient <0.25 = 83% stability, Contribution equity = 91% stability, Exit options present = 45% stability, External threat present = 77% stability.
Business Application of Three-Party Coalition Stability
Three-party coalitions need equal interdependence - any two-party sub-coalition viability creates instability. Airbus validates this: France+Germany can't build aircraft without UK wings, so the three-party (plus Spain) coalition is stable. Design coalitions so no two-party sub-coalition is viable through geographic integration, technology integration, market integration, and financial integration.