Dunbar's Number
Most organizations should limit coalition size to 8-10 members unless they can invest heavily in institutional infrastructure.
Robin Dunbar's research: Humans can maintain ~150 stable social relationships (cognitive limit for tracking reciprocity, status, and relationship history).
For business coalitions, the effective limit appears lower (~15-20 organizational relationships) because: Organizations are collections of people, not individuals (tracking 'Company A's behavior' requires monitoring multiple executives, divisions, actions), Business relationships require formal agreements (cognitive + administrative overhead), Executive time is limited (can't spend 30% of day grooming 20 partners like chimps do).
Empirical evidence: Successful long-term coalitions nearly all have ≤15 members (Airbus 4, early EU 6-12, functional OPEC core 8-12). Failed large coalitions: OPEC+ at 23 members (constant violations), WTO at 164 (gridlock).
The fundamental limit: Beyond 15-20 members, coalitions either develop strong institutions (rare, expensive), fragment into sub-coalitions (unstable), or become nominal coalitions (cooperation in name only).
Business Application of Dunbar's Number
Most organizations should limit coalition size to 8-10 members unless they can invest heavily in institutional infrastructure. The mathematics: Relationship overhead scales as N(N-1)/2. At 10 members = 45 relationships (manageable). At 20 members = 190 relationships (impossible).
Discovery
Robin Dunbar (1992)
Discovered cognitive limit of approximately 150 stable social relationships based on neocortex size
Dunbar's Number Appears in 2 Chapters
Effective business coalitions rarely exceed 15-20 members because relationship overhead scales quadratically - 190 relationships at 20 members is impossible to maintain.
Coalition size limits →Despite debate about the precise number, companies consistently report transitions around 150 employees where informal coordination breaks down.
Dunbar's number in organizations →