Emergence
Higher-order behaviour arises from lower-order interactions and can't be predicted from the parts.
Neurons interact and consciousness emerges, somehow. Individual traders interact and markets emerge, with properties no individual trader has. Termites interact and complex termite mounds emerge.
Emergent properties can't be derived from a study of the parts alone. You have to study the interactions. This is a deep limitation on reductionist analysis: the parts don't add up the way the whole behaves.
For operators, the practical implication: many organisational properties (culture, brand, productivity, trust) are emergent. They can't be installed directly. They arise from patterns of interaction over time. Trying to change them by edict usually fails. Changing the interaction patterns can change the emergent property.
Examples in the wild
Culture is emergent. CEOs who try to change culture by writing values on the wall usually fail. The ones who succeed change the interaction patterns (meetings, rewards, hiring, who speaks first) and let the new culture emerge.
Stock prices are emergent from many traders' decisions. No single trader's mental model captures the actual market behaviour. This is one reason market prices surprise even smart investors.
A relationship's character is emergent from thousands of small interactions. You can't reach in and change "the relationship" directly. You can change the interactions, and the relationship changes.
Emergence is one of the mental models we apply through real cases inside the Pareto MBA — a part-time program for professionals who want to think clearly about business.