Part of my writing is an exploration of themes in unintended consequences and second-order effects. Today’s post is a first introduction to the broad phenomenon of emergence. This topic is something I’ll return to again, so we’re just introducing the term today.
Emergence occurs where the parts of a system interact to form something different from what each part contributes independently. It’s a concept that takes some time to understand at a basic level, though emergence happens all around us. Some common examples include the way hydrogen and oxygen atoms combine to form water (very different in combination from the individual atoms), how water molecules combine to form drops (again different from individual molecules with properties like surface tension), and how drops of water combine to form rivers and oceans (different again with their currents and waves). There are many other examples, from individual birds (or fish) forming flocks (or schools) that move differently than the individuals would by themselves, to consciousness emerging from our physical brains…
A system displays emergence when its individual components interact and behave differently in the whole than they do individually. There is a difference between behavior in the macro and micro states.
This is a large, loose field of study where you often see a misquote from Aristotle, usually something like “the whole is greater than the sum of its parts.” But his actual quote is different and the difference is important. And Aristotle returned to the principle of emergence multiple times in his writing. Here are a couple examples.
“To return to the difficulty which has been stated with respect both to definitions and to numbers, what is the cause of their unity? In the case of all things which have several parts and in which the totality is not, as it were, a mere heap, but the whole is something beside the parts…” — Aristotle, Metaphysics, Book VIII, Part VI
Not a mere heap… Rather than “the whole is greater than the sum of the parts,” we have “the whole is something beside the parts” — a different meaning and one that I think better represents emergence. Emergence is not about being greater or less than something without that quality. (After all, how would we define “greater” or “less”?) Instead, emergence is a quality of a system’s parts that interact in new ways as part of a system.
There is another quote from Aristotle I’ll mention about the interplay between the whole and the parts:
“…for in all things which form a composite whole and which are made up of parts, whether continuous or discrete, a distinction between the ruling and the subject element comes to fight. Such a duality exists in living creatures, but not in them only; it originates in the constitution of the universe; even in things which have no life there is a ruling principle…” — Aristotle, Politics, Book I, Part V
This is another important understanding — that emergence exists both in the living (the birds / flock and fish / school examples from above) and the non-living (water-related examples). Though here, who is the ruler and who is the subject? Is the ruler the set of rules used by the subjects — the rules birds and fish use for keeping a distance from their neighbors, in this example?
Russ Abbott’s paper “What Makes Complex Systems Complex” provides more background. Abbott writes about Static, Dynamic, and Adaptive emergence. A few quotes will introduce these types here.
“Static emergence focusses on fixed, stable, and typically purely physical entities. To the extent that they can be considered systems at all, the products of static emergence are closed systems at equilibrium.
“Dynamic emergence focusses on entities that must continually renew themselves. Entities based on dynamic emergence are open systems and must continually find and import energy and other resources. Dynamically emergent entities can often be understood as agents. They interact with each other and with the environment.
“Adaptive emergence is probably the most important category from a societal perspective. Policy makers respond continually to newly emergent properties and patterns of behavior. At the same time, they must avoid policies that will produce unwanted adaptations.”
But emergence is not predictable based on a study of the individual parts. How can we limit exposure to unwanted effects?
We will return to this topic.
Future topics to investigate for emergence will include the hipster/mainstream populations, dance, the family, and government programs.
Considerations
- There can be rapid, large output differences from small input changes, while there is no or small change at the micro level. That means that there is a discontinuous system level, rather than a gradual continuous transition.
- Some views of emergence include that everything has it — and you can imagine how that is the case if everything is part of a system of some sort.
- Emergence is not restricted to complex systems, since you see abrupt phase transitions in things such as water at the boiling point.
- How can we limit exposure to unwanted effects?
