What is emergent complexity?
Emergence or emergent complexity describes how relatively simple interactions among parts at one level of scale can generate a qualitatively more complex whole at a greater level of scale. Common examples involve how the interactions of subatomic particles give rise to atoms, how the interactions of atoms give rise to molecules, and how the interactions of molecules give rise to various forms of matter. Emergence gives us language for addressing the surprising and wondrous times in which we find order where we should expect to find chaos.
We are focusing on three main themes related to emergence: patterns of part-whole interactions, levels of scale, and perspective.
Patterns of part-whole interactions
We have to be careful with how we think about wholes, parts, and their relationships. There are entire taxonomies for describing these meronymic or part-whole relationships, and any single whole can have different types of parts. For a whole pie, a part could be an individual slice, the crust, or even an ingredient. In each of these cases, we can take away the part and the remainder will still exist in some form. However, from an emergent systems perspective, we are referring to parts whose interactions cause the whole to come into being. For example, we can say that molecules are part of a pie. However, it is not possible to separate these types of parts from the whole and still have a whole. That is, a pie cannot exist in the absence of its molecules.
Levels of scale
There is the idea that “the whole is greater than the sum of its parts”, but emergence literally takes this idea to another level. What we’re getting at here is the difference between affect and effect. Because an emergent whole is an effect of its parts, it exists at an inherently greater magnitude or level of scale. These levels represent distinct situational contexts which subsequently afford and constrain distinct behaviors or patterns of interaction. This is reflected in the differences between the physical properties of objects we interact with everyday and the properties of objects at smaller (cells, molecules, atoms, etc) or greater (planets, stars, galaxies, etc) levels of scale, even though all are subjected to the same fundamental forces.
Emergence is a means of making simplicity complex and complexity simple. What is relatively complex at one level of interacting parts is also relatively simple at another level in which the parts manifest as a whole. Every phenomenon we can observe in the world is both a part and whole, and all are constantly involved in endless interactions which are invisible to us because they are either too small or big for us to physically see, or too utterly beyond our ability to mentally comprehend. Whether or not something is described as an emergent process depends upon a person’s subjective perspective, rather than the objective nature of the thing itself.