This chapter uses the representative examples of complex systems discussed in the previous chapter to arrive at a list of the distinctive features of complex systems. These features include numerosity; disorder and diversity; feedback; and non-equilibrium. The interesting thing about complex systems is that these conditions can give rise to the following products: spontaneous order and self-organisation; nonlinearity; robustness; nested structure and modularity; history and memory; and adaptive behaviour. Not all these features are present in all complex systems. Whenever any of the products are found in a system, they are the collective result of the conditions, but not all the products are found in all complex systems. Often products help produce other products — for example, memory is impossible without a degree of robustness, and adaptive behaviour can build nested structure and modularity. The chapter considers each of them in turn in more detail and assesses whether each is necessary and/or sufficient for complexity on any or some conceptions of what complex systems are.
Simple rules and self-organisation: A complex systems’ perspective on South Africa’s COVID-19 response