Emergent behavior is behavior of a whole that is different than behavior of its parts. In otherwise, an emergent system is better understood as a single entity, despite being composed of many smaller and somewhat independent entities. With each subcomponent operating to some degree autonomously, the emergent behavior emerges out of the interaction between subcomponents.
Emergence is a concept from philosophy, systems theory, art, and science, especially biology, chemistry, and sociology.
- Insect colonies
- The cells in a human body: each cell acts to some degree autonomously, but they are each willing to sacrifice themselves for the benefit of the organism, similar to how an ant in an ant colony is willing to sacrifice himself in service to the queen.
- The behavior of a herd
- Emergent behavior in game design (starts 11:56), where things that happen in the game are not pre-scripted but rather emerge from the game's systems.
- When you ride a bike, the forward motion happens because of how the rider and the bike interact, neither the bike nor rider can go that fast own their own.
- The operations of large, particularly bureaucratic, organizations, such as a corporation. The individualist philosophy would attribute each action to a specific person. This philosophy is not enough to account for the actions of sufficiently large organizations. When we say "the company did X," we do not necessarily mean that one person in the company decided to do X. Sometimes, decision making processes are so complicated and opaque that it is hard to attribute decisions to a single person. Each employee is simply following rules and processes set in place by others.
- Cellular autonoma
This is sometimes called emergentism. Things are "irreducibly complex" if removing any subcomponent would make the whole thing stop functioning.
The question with irreducibly complex systems is how they came about in the first place. In some situations, there are intermediate bridge states, so removing each subcomponent makes the thing behave in a way that is different but not useless. Other times, for the thing to come about requires crossing an adaptive valley.