[[John Holland]] (1929–2015) was an American scientist and psychologist at the University of Michigan, a founder of the [[Santa Fe Institute]], and the person who named the [[complex adaptive systems]] field. His background was unusual: the first PhD in computer science awarded in the United States, supervised by [[Arthur Samuel]], working on neural networks decades before they were fashionable. His central question was how adaptation works — not in the slow Darwinian sense alone, but in systems that learn and evolve in real time. He answered it by building them: **genetic algorithms**, search procedures that breed solutions through mutation, crossover and selection, now foundational to evolutionary computation. His 1995 book *Hidden Order* sets out the framework: agents, aggregation, nonlinearity, diversity, flows — the signature of a complex adaptive system — and the notion of *emergence* as aggregate behaviour that cannot be read off the parts. A later short book, *Emergence: From Chaos to Order* (1998), pushed the idea further. The habit worth borrowing from him is his shorthand definition, quoted in [[Complex Adaptive Systems]]: a complex adaptive system is the *aggregate behaviour of adaptive agents* — no manager, no plan, just local rules and interaction. [Santa Fe Institute profile](https://www.santafe.edu/people/profile/john-holland) [John Holland (Wikipedia)](https://en.wikipedia.org/wiki/John_Henry_Holland) `Concepts:` [[Complexity Theory]] · [[Complex Adaptive Systems]] `Knowledge Base:`