This post was inspired by the following video:
Cool, right? Can you see what happens there? A much more detailed understanding than mine is possible, but to the extent that I can describe it, it goes like this: The pendulums swing at different speeds due to the difference in their lengths. Each of them goes its regular way unaffected by the others. But waves form along the length of the row of pendulums nevertheless because of the mathematical relations between the periods of the swings. The pendulums’ movements combine into different patterns that are immediately recognisable to us as patterns. If you follow any individual pendulum, all it does is swing back and forth at its own rate. Any faster pendulum will catch up to any slower one, and this accounts for the changes of patterns.
The interesting thing here I want to draw attention to is twofold: First, the system works by certain rules, the rules that swinging pendulums follow. But as it functions, it makes up new rules based on those simple rules. All those changing waves are as inevitable under the circumstances as the swing back and forth of individual pendulums, even though the system was built, so to speak, on only the normal pendulum rules without any rules for waves. There are rules that get built automatically on more basic rules. Secondly, and very much related, none of the individual pendulums by themselves have the properties that the system made up of them has as a whole. They just swing back and forth; the system as a whole contains waves and patterns.
These kind of properties that the system as a whole has that its components do not and that act on rules implicit in the more fundamental rules of the system are called emergent. (Alternatively, supervenient. Those words usually mean the same thing. There are different varieties of definition, but I’ll not be so specific here as to need to go into that.) Emergent properties aren’t just a cool oddity as here. They’re everywhere. Heat, for example? Individual molecules don’t have temperature. They just move around at different speeds. How fast they move on average in a piece of matter amounts to how hot that piece of matter is, crudely speaking. Heat is a very real physical property, but looked at too closely, it disappears into the dance of the particles.
This isn’t the whole story, though, and that video only demonstrates part of what goes on in emergence in nature. The pendulums aren’t interacting, and that keeps their combined behaviour relatively simple. When a system like that is also able to affect itself, so that what it does next is based on the patterns it previously developed, it can develop properties and behaviours so complicated they can’t be predicted other than by going through every phase of action step by step and seeing what happens next. Then we can really talk about chaos, complexity and complicity. But I’ll keep this simple and not go into that here.
Almost everything we know about the world around us is knowledge about emergent phenomena and dynamics. Everything is presumably based on a few basic physical laws, some quite crazy ones at that according to quantum mechanics, but that’s not what we’re seeing around us. Understanding the basic laws wouldn’t enable us to understand anything about the world except for systems of a few particles anyway, because we’d be stuck trying to calculate the behaviour of endless amounts of particles (such as a person and their environment) for the simplest things. But we don’t really need to, because those particles get together into bigger systems that act together by new emergent rules we can deal with, even if a lot of the rules we use in everyday reasoning are very vague compared to the laws of physics.
There being stars, planets and solar systems is an emergent dynamic. It follows basically from gravitation, but gravitation doesn’t contain any direct rules about spheres forming to orbit each other. (It can be completely described without any mention of such.) Life is an emergent dynamic. It acts on the laws of physics and mathematics, but it forms systems that have their own rules, like natural selection. And it seems evident our mental properties are emergent, dependent on the structure of the physical matter forming our bodies and especially brains, the matter not having those properties as such. How exactly there being mental properties works is quite baffling anyway, but the idea of emergence can say a lot about it, even though there are still a lot of questions about that that I can’t figure out an answer to, with or without emergence.
This is only a glimpse at the idea of emergence. It’s an extremely fascinating thing, a sort of general rule of the universe (though an emergent one!), a principle existing above specific laws of nature but still granting understanding into them. I highly recommend anyone interested to read more about it in the works of actual experts. As one example, Ian Stewart and Jack Cohen discuss it on a general and not very technical but still deep level in some of the books they have written together.