Eliezer: I generally like your posts, but I disagree with you here. I think that there's at least one really useful definition of the word emergence (and possibly several useless ones).
It's true, of course (at least to a materialist like me), that every phenomenon emerges from subatomic physics, and so can be called 'emergent' in that sense. But if I ask you why you made this post, your answer isn't going to be, "That's how the quarks interacted!" Our causal models of the world have many layers between subatomic particles and perceived phenomena. Emergence refers to the relationship between a phenomenon and its immediate cause.
So, for instance, suppose I'm on the interstate and I get caught in a traffic jam. I might wonder why there's a huge jam on the road. It's possible that there's a simple, straightforward explanation: "There's a ten-car pileup a mile further on, and five of the six lanes are shut down. That's why there's a traffic jam." Obviously we could get far more reductionist— both in terms of "why is there a pileup" and "why does a pileup cause a traffic jam"—but for the conceptual level we're operating on, the pileup is a full and complete answer. And thus the traffic jam isn't an 'emergent' phenomenon; it has one major identifiable cause.
In contrast, a lot of traffic jams 'just happen.' The previous sentence is false, strictly speaking; the jams come from somewhere. But you can't point to an individual cause of them; they arise from the local effects of millions of local actions taken by individual drivers. Removing any one of these actions wouldn't eliminate the jam; it's a cumulative product of all of them. So people searching for an explanation of why it takes two hours to dive ten miles in rush hour get really frustrated, because there's no good explanation to give them. And people trying to fix rush hour get even more frustrated, because there's no good angle to attack the problem from.
So emergence, in this sense, means that a phenomenon has many intertwined causes, rather than one or two identifiable and major causes. It turns out, of course, that most interesting phenomena are emergent (non-emergent phenomena are, by definition, boring, since their causes are straightforward). But "emergence" is useful as a shorthand for "the causes are complicated and interconnected, and I can't pick one out and tell you, 'here it is, this is why that happened.'" It's important not to get confused, and not to think an explanation of why we don't understand something is the same as an explanation of that thing. But as long as you remember that, it's a useful thing to remember.
In contrast, a lot of traffic jams 'just happen.' The previous sentence is false, strictly speaking; the jams come from somewhere. But you can't point to an individual cause of them; they arise from the local effects of millions of local actions taken by individual drivers.
I've actually seen a study on these types of jams, though I cannot remember the source. The results were pretty simple and surprising. The research discovered they could create a massive traffic jam on a full but still flowing highway by simply having a single car brake for longer t...
The failures of phlogiston and vitalism are historical hindsight. Dare I step out on a limb, and name some current theory which I deem analogously flawed?
I name emergence or emergent phenomena—usually defined as the study of systems whose high-level behaviors arise or “emerge” from the interaction of many low-level elements. (Wikipedia: “The way complex systems and patterns arise out of a multiplicity of relatively simple interactions.”)
Taken literally, that description fits every phenomenon in our universe above the level of individual quarks, which is part of the problem. Imagine pointing to a market crash and saying “It’s not a quark!” Does that feel like an explanation? No? Then neither should saying “It’s an emergent phenomenon!”
It’s the noun “emergence” that I protest, rather than the verb “emerges from.” There’s nothing wrong with saying “X emerges from Y,” where Y is some specific, detailed model with internal moving parts. “Arises from” is another legitimate phrase that means exactly the same thing. Gravity arises from the curvature of spacetime, according to the specific mathematical model of General Relativity. Chemistry arises from interactions between atoms, according to the specific model of quantum electrodynamics.
Now suppose I should say that gravity depends on “arisence” or that chemistry is an “arising phenomenon,” and claim that as my explanation.
The phrase “emerges from” is acceptable, just like “arises from” or “is caused by” are acceptable, if the phrase precedes some specific model to be judged on its own merits.
However, this is not the way “emergence” is commonly used. “Emergence” is commonly used as an explanation in its own right.
I have lost track of how many times I have heard people say, “Intelligence is an emergent phenomenon!” as if that explained intelligence. This usage fits all the checklist items for a mysterious answer to a mysterious question. What do you know, after you have said that intelligence is “emergent”? You can make no new predictions. You do not know anything about the behavior of real-world minds that you did not know before. It feels like you believe a new fact, but you don’t anticipate any different outcomes. Your curiosity feels sated, but it has not been fed. The hypothesis has no moving parts—there’s no detailed internal model to manipulate. Those who proffer the hypothesis of “emergence” confess their ignorance of the internals, and take pride in it; they contrast the science of “emergence” to other sciences merely mundane.
And even after the answer of “Why? Emergence!” is given, the phenomenon is still a mystery and possesses the same sacred impenetrability it had at the start.
A fun exercise is to eliminate the adjective “emergent” from any sentence in which it appears, and see if the sentence says anything different:
Another fun exercise is to replace the word “emergent” with the old word, the explanation that people had to use before emergence was invented:
Does not each statement convey exactly the same amount of knowledge about the phenomenon’s behavior? Does not each hypothesis fit exactly the same set of outcomes?
“Emergence” has become very popular, just as saying “magic” used to be very popular. “Emergence” has the same deep appeal to human psychology, for the same reason. “Emergence” is such a wonderfully easy explanation, and it feels good to say it; it gives you a sacred mystery to worship. Emergence is popular because it is the junk food of curiosity. You can explain anything using emergence, and so people do just that; for it feels so wonderful to explain things.
Humans are still humans, even if they’ve taken a few science classes in college. Once they find a way to escape the shackles of settled science, they get up to the same shenanigans as their ancestors—dressed up in the literary genre of “science,” but humans are still humans, and human psychology is still human psychology.