Hmm, interesting. I've never actually realized that people used "emergent behavior" as a model or an explanation for anything. In that context, I'd always treated it as just a description, with the meaning that an "emergent phenomenon" is a "complex or seemingly complex phenomenon arising from interactions of a large number of very simple subparts," or something of the sort. Never thought of it as a model or an explanation, but just as a reasonable descriptive word. But if it is used as an attempted explanation to end discussion, then it's just functioning as a curiosity-stopper and should be questioned further.
What are phenomena that aren't "emergent"? I guess Eliezer is right when he says "a single quark". I think Eliezer makes a good case that the word is overused, and doesn't enlighten the discourse.
It might be more useful to describe things in reverse " X are the components of phenomenon Y". Such as "Neurons firing are the known components of intelligence". Because when we observe something, it can be useful to ask "what are its components"?
It contrast, everything observed IS the component of some bigger system, but it can be also useful to ask, what is the next biggest ordered system it is a part of, etc. That's where "emergent phenomena" might legitmately come in. Because an ant colony might be the next biggest ordered system that an individual ant is a part of, and that does seem like useful information.
Okay, but that's really not how I have understood emergence. It delineates a subject matter, and does so in an abstract way that includes many specific examples which are purportedly alike in some important way. But I don't think this use necessarily implies that the explanation has thereby been given. It is, rather, usually an attempt to delineate a subject matter which can be further investigated. I believe that the hope is that a general theory of emergence is possible, though my impression is that there isn't even a generally agreed-upon definition of it, let alone a commonly accepted theory.
One common element that I have sometimes noticed is that an emergent phenomenon can be idealized and a simplified mathematical model constructed of it, which is not precisely correct but which is a very good approximation. The existence of such simple and very good models is remarkable and extremely lucky for us.
For example, an actual fluid such as water is really made up of molecules that interact, but there is a simple mathematical model for fluids which treats fluids as absolutely continuous and smooth all the way down, not composed of atoms but fluid at every scale. As I vaguely recall,...
In line with previous comments, I'd always understood the idea of emergence to have real content: "systems whose high-level behaviors arise or 'emerge' from the interaction of many low-level elements" as opposed to being centrally determined or consciously designed (basically "bottom-up" rather than "top-down"). It's not a specific explanation in and of itself, but it does characterise a class of explanations, and, more importantly, excludes certain other types of explanation.
I would think that something like "life/intelligence is an emergent phenomenon" means "you don't need intelligent design to explain life/intelligence".
I remember when Warren Spector & Harvey Smith were going on about emergence in videogames. I think their definition was something like "a non-obvious [it may even surprise the designers] outcome of a system of rules rather than something scripted". That's a rather subjective definition but it seems to fit as well for the things that are described as "emergent" in real life. Since life is not actually a videogame but has universally valid rules, it would not be a very useful concept for that domain. I think Wolfram has written a lot ...
I'm getting the feeling that Eliezer is starting to get overly eager to attack semantic stopsigns. I recommend magic oil in the evening and emergent phenomena in the morning.
My impression of "emergence" was that it's closely related to pattern recognition. You have atoms A, B..ZZZZZZZZZZ, and you recognize that these atoms form a certain pattern. So you say that a supercluster of galaxies/bar stool/intelligence "emerges" from a bunch of atoms.
I once had a prolonged debate with an anticognitivist. He, as usual, argued that no matter what...
Aren't superconductivity and ferromagnetism perfect examples of emergent phenomena? I'm not saying that calling something an emergent phenomenon adds any deeper understanding of it. But I think there certainly are phenomena that can be fairly called as emergent.
Aren't superconductivity and ferromagnetism perfect examples of emergent phenomena?
Yes. So are non-superconductivity and non-ferromagnetism. That's the problem.
Uh. No. Non-superconductivity is not usually considered as an example of emergence. Because the non-superconductive system is composed of smaller subsystems which are themselves non-superconductive. Same goes for non-ferromagnetism. Not "emergent" because nothing new is emerging from the collective that was not already present in the components.
And even if what you wrote were true it would be a problem only if emergence were being used as an explanation. But, outside of the philosophy literature, it almost never is used that way. You are tilting at windmills here.
I don't buy the analogy between emergence and phlogiston or vitalism. Offering up "emergence!" as an explanation of a phenomenon is a category mistake, to be sure, and is a semantic stopsign when misunderstood this way.
As other commenters have noted, however, there is a proper understanding of emergence that is useful. (In philosophy, for instance, it's an admittedly sloppy but still useful term to classify different kinds of explanations of consciousness). This doesn't seem true of explanations that appeal to phlogiston or vitalism. Vitalist explanations aren't category mistakes. They're simply vacuous explanations, full stop.
Creeping into his soul, he felt the first faint tinges of despair.
After all these posts on how the strength of an idea is what it excludes, forbids, prohibits, people are still citing positive examples as proof of the power of emergence? Tell me what it isn't!
Hmmm...
What isn't emergence? Well, on a trivial level, everything observable is a consequence of physics. So, is there anything observable that does not fall into the category of "physics", and does that make the category meaningless?
I think I can come up with some things that "emergence" is not.
If X is not "emergent", then: a) X does not have a cellular automata-like model; there are no readily identifiable components of X that follow relatively simple, computable rules which generate the observed behavior of the system. (The...
"Black holes, dark matter and dark energy seem to pretty much fit this description. They are, after all, inventions tacked on to calculations, in order to make theory and calculation fit observations."
See http://en.wikipedia.org/wiki/Bullet_cluster for dark matter.
There are a few examples of non-emergence. For example, if we tessellate many small equilateral triangles to create a larger equilateral triangle, the resulting figure will not show any emergent properties.
Outside of mathematics, though, the concept is vague and I can't see much use for it as applied to specific phenomena.
For example, if we tessellate many small equilateral triangles to create a larger equilateral triangle, the resulting figure will not show any emergent properties.
On the contrary - the large shape emerges from all the small shapes! Isn't it wonderful? You can even get the same behavior on the higher level as on the lower level, only this time, it's emergent!
...is what an emergence advocate would say, if they wanted to claim yet more territory for their ever-growing kingdom.
If we take EY's example of a market crash, the non-emergent hypothesis is that of a random process. In other words, price action is like the action of gas molecules, or Brownian motion. To say that a market crash is an emergent phenomenon is to say that it displays more order than gas molecules bouncing off one another, which do not display emergent properties. That is not an empty distinction, as far as I can see.
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 f...
"Even better: A colony is made of ants. We can successfully predict some aspects of colony behavior using models that include only individual ants, without any global colony variables, showing that we understand how those colony behaviors [emerge] from ant behaviors."
Emerge and arise are synonyms. I'll agree with your desire to quell the potential overuse of "emergent," however as is well outlined above there is a specific testable model being proposed when emergent is used closer to correctly. That is that there is no system-wide varia...
In most of the contexts in which I have seen the word "emergent used", it has signified a lack of understanding of the underlying causes of the phenomenon being described but rather than acting as a semantic stop-sign seemed to be used as its exact oppposite - as a marker for an area sufficiently interesting to be deserving of further research with a view to eventual full explanation. But perhaps I've been misunderstanding the intent of the authors.
"After all these posts on how the strength of an idea is what it excludes, forbids, prohibits, people are still citing positive examples as proof of the power of emergence? Tell me what it isn't!"
I thought I did. (Even if Jadagul expressed what I was grasping towards much better than I did.)
I'm pretty ignorant on this, but I always thought that the phrase related to complex outcomes that result from surprisingly simple systems, so that the complexity is "emergent".
One example is chaos. One can have chaotic non-linear dynamic systems and non-chaotic non-linear dynamic systems.
But, again, I could have misunderstood.
Jadagul's example seems to me to be a clear place where the term emergence is useful. Phil Goetz has given others in the past. OTOH, it still seems that in most of the cases where emergence is used as a synonym for "magic" much too often. 'Emerges from' seems to be less strong evidence for a legitimately useful term than than 'emergent', as 'chaotic' seems to be a perfect synonym for the latter.
Even in the case of 'chaotic', the tendency to use the term as a stop-sign is serious. A great deal of understanding of chaotic systems is possible (t...
We can successfully predict some aspects of colony behavior using models that include only individual ants, without any global colony variables, showing that we understand how those colony behaviors arise from ant behaviors.
But that is just what is meant to be conveyed by the claim that intelligence emerges from the interaction of neurons. Of course that is trivially true. But, the original AI theory was that neurons were the building blocks of a universal computer (and how the universal computer was built of neurons wasn't particularly interesting). Th...
"Tell me what it isn't!"
I'll go with TGGP's domain (video games), since that is what we blog about at Kill Ten Rats. The gaming blogosphere uses the term "emergent gameplay" more or less as TGGP defines it. Going back to my first online game, Asheron's Call, an example of what is not "emergent" gameplay is characters slaying monsters and leveling up. Monsters have the same code, but rarely win, so they rarely level; an example of emergent play was having characters sacrifice themselves to bunnies, who would gradually level ...
"Tell me what it isn't!"
The examples I gave, superconductivity and ferromagnetism, are example of phase transitions, which only happen when there are large number of components interacting. I wouldn't call phenomena that can be explained by one or few components as emergent. So, I wouldn't call a black hole as emergent. I wouldn't call an electron and a proton making up a hydrogen atom as emergent. I wouldn't call two hydrogen atoms and an oxygen atom forming a water molecule as emergent. But liquid that is formed by a large number of water molecules is an emergent phenomenon to me. Jagadul's example of traffic jam is also a good one.
I'm pretty out of my depth here, but I'll echo what some people have said above. Before people started scientifically doing either one, would it have been obvious that a simple model would be very successful at predicting the behavior of, say, subatomic particles but would be very unsuccessful at predicting the weather? That is, it seems like there really are some phenomena where it is more true and others where it is less true that predictions can be generally and successfully made using straightforward intuitive models. It seems like the label "emergent" is just a (useful) label for the stuff where this can't be done.
BJK is on to something: the non-emergent description of a market crash is something like "IF the Fed is raising rates and the economy is slowing down and investors are too leveraged and ... ... ... then the market will crash," while the emergence theory might define investor behavior and note that it will result in periodic booms and crashes, without special rules to govern either. That's the essence of emergence: simple universal rules rather than complex specific rules.
It might feel like junk science because it crosses disciplinary borders, but that doesn't make it invalid.
Don't y'all find it a little suspicious that so many people think "emergence" is a useful concept, yet have different definitions of what it is? (Though more important is what it isn't.)
Next stage in the gauntlet: Why is this a useful concept? Why does it increase your understanding of the universe, and your predictive power? Can you force me to talk about emergence or a concept isomorphic to it?
I disagreed Rip's opinion that black holes etc. are examples of emergent phenomena, but other than that I don't really see much disagreement about what emergence is in the comments here.
I like Zubon's description "the whole is not predictable from the parts" and "No cell in your brain understands Chinese,..., but the system as a whole does."
Why can it be useful? I can think of two possible reasons. There is a certain reductionist tendency (although I don't think being reductionist per se is bad) to assume that we get better and better...
The concept of emergence is useful as a guard against certain errors, such as, for example, conspiratorial theories which explain phenomena as the product of intentions (malign or benevolent). Order does not always arise from intention. If society is lawful, that is not necessarily because there is some commander dictating that it be lawful. The lawfulness of society may be a phenomenon with a mostly dispersed, decentralized cause (e.g., lawfulness may be in large part enforced by ostracism of transgressors and thus enforced by all members of society rathe...
"Tom McCabe, that is not proof."
There is no such thing as proof. See http://www.acceleratingfuture.com/tom/?p=11.
Mainstream astronomers' predictive abilities are shoddy at best. It seems as if every new observation is "surprising," or "shocking," or "baffling."
Yet there are still no direct observations of dark matter.
How deep can biases run? Could it have poisoned the very foundation of modern science? I think it's something to investigate, especially considering the vast sums of money that are at stake if some mainstream theories turn out to be wrong or pointless.
"It seems as if every new observation is "surprising," or "shocking," or "baffling." "
Surely the underlying reality of this "seeming" is that a large fraction of new newsworthy observations is "baffling" etc.
I ll try a silly info-theoretic description of emergence:
Let K(.) be Kolmogorov complexity. Assume you have a system M consisting of and fully determined by n small identical parts C. Then M is 'emergent' if M can be well approximated by an object M' such that K(M') << n*K(C).
The particulars of the definition aren't even important. What's important is this is (or can be) a mathematical, rather than a scientific definition, something like the definition of derivative. Mathematical concepts seem more about description, representation, and modeling ...
True.
I don't have any direct quotes or statistics available at hand, but I think however that it is not disputed that our understanding of the universe is nowhere near complete. And with so many newsworthy observations that don't fit mainstream theory, then surely that must suggest a problem with the theory.
The shape of galaxies could not be explained with visible matter. As a result, the theory wasn't scrapped; they instead simply added enough matter to the equation to make it work -- hence dark matter (which has to have much more mass than visible matter...
Eliezer: "Don't y'all find it a little suspicious that so many people think "emergence" is a useful concept, yet have different definitions of what it is?"
That's a non sequitur. Different people define intelligence differently, so what? The fact that they don't understand intelligence doesn't mean that it isn't a useful concept.
When people actually can't agree on the meaning of a word, the signnal to noise ratio drops from using it. But in that case, instead of discarding the word, people just need to standardize it.
Emergence is an annoyingly vague concept, but that doesn't mean it's an empty one.
One meaning of emergence is "decentralized control". In a free market economy, prices and other properties are emergent from a large set of transactions among distributed agents, in contrast to a centrally planned and controlled economy. So there's something that is not emergent, or less emergent. Similarly, it used to be thought that a bee colony was controlled by the queen, but now we know that its activity is also the result of the work of distributed agents. I...
"Let K(.) be Kolmogorov complexity. Assume you have a system M consisting of and fully determined by n small identical parts C. Then M is 'emergent' if M can be well approximated by an object M' such that K(M') << n*K(C)."
That seems to describe what I described earlier:
"One common element that I have sometimes noticed is that an emergent phenomenon can be idealized and a simplified mathematical model constructed of it, which is not precisely correct but which is a very good approximation."
I didn't, by the way, intend this as a definition of emergence, though it or something thereabouts might qualify.
Eliezer: Here's another example similar to ones other people have raised, a story I heard once, that might explain why I think it's an important and useful concept.
Supposedly, in the early nineties when the Russians were trying to transition to a capitalist economy, a delegation from the economic ministry went to visit England, to see how a properly market-based economy would work. The British took them on a tour, among other things, of an open-air fresh foods market. The Russians were shown around the market, and were appropriately impressed. Afterward...
In line with previous comments, I'd always understood the idea of emergence to have real content: "systems whose high-level behaviors arise or 'emerge' from the interaction of many low-level elements" as opposed to being centrally determined or consciously designed (basically "bottom-up" rather than "top-down"). It's not a specific explanation in and of itself, but it does characterise a class of explanations, and, more importantly, excludes certain other types of explanation.
This comment hits the bullseye. The general idea of...
In line with previous comments, I'd always understood the idea of emergence to have real content: "systems whose high-level behaviors arise or 'emerge' from the interaction of many low-level elements" as opposed to being centrally determined or consciously designed (basically "bottom-up" rather than "top-down"). It's not a specific explanation in and of itself, but it does characterise a class of explanations, and, more importantly, excludes certain other types of explanation.
This comment hits the bullseye. The general idea of...
"As a result, the theory wasn't scrapped;"
By "the theory" you mean general relativity, which is one of the most well-confirmed theories in all of physics. You can't just come up with a slightly modified version of GR to accommodate weird observations; the Einstein field equation is a unique solution because of all the demands placed on any reasonable theory of gravity. If you assume:
Eliezer, I wonder whether the reason you think "emergence" isn't a useful concept is just that it seems so obvious to you that every phenomenon must fit the proposed definition that it doesn't exclude anything that's meaningful for you. (This seemed to be implied in your original post.) Even so, it can still be a useful concept as long as some people think that there could be non-emergent phenomena.
And yes, the proposed definitions of emergence are vague, but, as has already been pointed out, that doesn't imply the concept is worthless.
"Don't y'all find it a little suspicious that so many people think "emergence" is a useful concept, yet have different definitions of what it is?"
I think "bias" is a useful concept, despite the tendency for people to disagree over what regions of failurespace count as "bias." (Uh, ahem).
Some other vague concepts people disagree on: 'cause,' 'intelligence,' 'mental state,' and so on.
I am a little suspicious of projects to 'exorcise' vague concepts from scientific discourse. I think scientists are engaged in a healthy enough enterprise that eventually they will be able to sort out the uselessly vague concepts from the 'vague because they haven't been adequately understood and defined yet'.
I do think there is a good deal of commonality among the reasonable comments about what emergence is and also feel the force of Eliezer's request for negative examples.
I'll try to summarize (and of course over-simplify).
When we have a large collection of interacting elements, and we can measure a property of the collection as a whole, in some cases we'd like to call that property emergent, and in some cases we wouldn't.
I can think of three important cases:
You do seem to be rising to the challenge. So here's the next questions:
1) Is the property you've described objective or subjective? Are you talking about the thing itself, or a perspective you have on it?
2) If subjective, does the perspective describe ignorance, or knowledge?
3) You can define the set of left-handed red-haired Canadian women, but this set probably does not have any interesting properties that can be inferred from it beyond the definition itself. What can you infer once you say that something is emergent?
Thanks, Eliezer. Regarding your questions:
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.