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,... (read more)

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 ... (read more)

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.

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... (read more)

"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.

I want to say that I like Jadagul's reply

"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... (read more)

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... (read more)

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... (read more)

"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 ... (read more)

"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.

Tom McCabe, that is not proof.

http://www.holoscience.com/news.php?article=stb9s0ye

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.

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... (read more)

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... (read more)

"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."

"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 ... (read more)

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... (read more)

"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... (read more)

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... (read more)

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... (read more)

"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:

• Spacetime is flat in the absence of matter;
• Spacetime curvature is linear with respect to the density of matter;
• The standard principles of mathematics (e

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:

• If we can compute the property as a simple sum or average of properties of the individual elemen

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:

Eliezer, although the comments did eventually get better, don't despair for the early comments on this post. Remember yourself, all you are finding in the comments is evidence confirming the belief that no one reading this blog is learning anything. I conjecture that those who have learned something just don't get excited enough to post because they don't disagree with you strongly enough or aren't sufficiently surprised to thank you publicly.

Of course, I still suspect, as you probably do, from years of experience that most readers of this blog believe ... (read more)

This thread appears to be missing references to support the notions that "emergence is commonly used as an explanation in its own right" and "many people think emergence is a useful concept, yet have different definitions of what it is".

"Intelligence is an emergent phenomenon" is a valid response to Searle-followers - who ask questions about how brains can be intelligent when no neuron is intelligent. AFAIK, the response doesn't pretend to be a complete theory about how brains work.

The word 'emergence' is an accent, not an explanation. It shifts focus to the idea that the system itself contains enough power or complexity to produce the effects wanted, when the mistake is to assume that the system doesn't have it. Let's show a simplistic example with ant colonies:

Ant colonies exhibit intelligence.
Ant colonies exhibit intelligent emergent behavior.

In the first statement, there is an easily ambiguated idea that intelligence is part of the ant colonies. This could mean one of many possible things in common speech:
- The ants themselves ... (read more)

I just came from a debate with a friend of mine about emergence, so here's a simple example of what emergence is and isn't that I just told to him. (That he rejected anyway.)

Let's take, as an example, a car. Motion is an emergent property in cars. (I'm talking about motion on the level we live on that allows whole objects to move great distances.)

The pieces of the car, gathered into a pile, could not move. So motion was not a property in the parts making up the car. Motion emerges when the parts are built into the complex relationship that makes up the car... (read more)

You will have to forgive me, as i am over three years late to get here since inception, and about six months late since the last comment, but surely rationality waits for all. I seek the help of rationalists more advanced then me because something still seems very flawed with the argument when I account for my previous understanding of emergence. As I understood it, emergence most recently came about when psychology hit a serious recursive (is that the right word?) question, that is namely "where is consciousness located in the mind?". To fram... (read more)

Well, I agree that that fake explanation is used too often, and that it only gets any cred because it's from the right literature genre. But I don't think the whole of work in emergence can really be reduced to a mystery to worship. Certainly "emergence" is a stupid noun, just like "Red-hood" is a stupid noun. And that's a wonderful exercise to shut up the anti-reductionist movement based around emergence.

But "emergently arising" and "arising" can be given useful different meanings without stretching things too far... (read more)

that description fits every phenomenon in our universe above the level of individual quarks...

What do you know, after you have said that intelligence is "emergent"? You can make no new predictions.

It is true that I can make no new predictions, and you can make no new predictions, but other people do make new predictions from the explanation "emergence".

"Emergence" is like "atheism" or "naturalism".

If a religious person learns only that a set of phenomena is the world is explained by naturalism, that pe... (read more)

The term "emergence" doesn't mean anything in and of itself, but it does mean something very particular when applied to specific systems. For example, one could say that oscillating patterns with a period of four generations and lateral motion of 1/2 cell per generation are an emergent phenomenon of cellular automata on a randomly filled square grid with 3/23 rules (gliders in Conway's game of life). You don't know whether any given cell is alive or dead, but it's a very good guess that given a modestly large board, there is a glider somewhere on that board. That's what I take "emergent phenomenon" to mean.

I believe I first came across the term emergence in relation to Langton's Ant, in a book section loosely centered on game theory. In the book, the patterns formed by the progression of Langton's Ant were termed 'emergent' because they could not be predicted except by running the program. One could not, with full knowledge of the simple rules that governed the Ant's world, predict what the pattern would look like after x iterations, or where the ant would be. Given this, I would not call the location of a dropped object at time t after the drop an 'emergen... (read more)

As Eliezer requested, I offer my view on what emergence isn't: emergence is not an explanation. When I say that a phenomenon is emergent, I am using a shorthand to say that I understand the basic rules, but I can't form even a simple model of how they result in the phenomenon.

Take, for example, Langton's Ant. The ant crawls around on an infinite grid of black and white squares, turning right at the centre of each white square and left ant the centre of each black square, and flipping the colour of the square it's in each time it turns.

The first few hundred steps create simple patterns that are often symmetric, but after that the patterns Langton's Ant produces become pseudorandom. If left to run for around 10000 steps, the Ant builds a highway - that is, it falls into a pattern of 104 of steps, and at the end of each cycle, it has moved diagonally and the cycle repeats. After millions of steps, the grid has a diagonal streak across it. As far as we know, the Ant always builds a highway.

Highways are emergent by the definition I use - that is, I know exactly how Langton's Ant works, and therefore, in theory, know why it builds a highway, but I can't form a model of its behaviour t... (read more)