Renormalization
How behaviour at one scale aggregates into different behaviour at larger scales.
A concept from physics: the rules governing tiny scales (atoms) aggregate up into different rules at larger scales (gases, solids). The micro and macro can look completely different even though one is built from the other.
In social systems, the same applies. Individual rational behaviour can aggregate into irrational collective behaviour (see [moloch-multipolar-traps]). Individual preferences can aggregate into surprising collective outcomes (see [minority-rule]). Reasonable people, interacting, can produce unreasonable systems.
For operators, the practical version is: don't assume the system behaves like its parts. Individual rationality doesn't aggregate to collective rationality. The right interventions usually target the system's emergent properties, not the individuals' decisions.
Examples in the wild
Companies full of individually reasonable people can have collectively unreasonable cultures. The aggregation of individual incentives produces emergent dynamics nobody chose.
Individual investors making sensible decisions can produce collective market behaviour that looks insane. The renormalisation from micro to macro is where bubbles and crashes live.
Traffic jams are renormalisation. Each driver makes reasonable decisions. The aggregate is a system that nobody designed and nobody likes.
Renormalization 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.