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The Futility of Emergence

33 Post author: Eliezer_Yudkowsky 26 August 2007 10:10PM

Prerequisites:  Belief in Belief, Fake Explanations, Fake Causality, Mysterious Answers to Mysterious 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 is explained by "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:

  • Before:  Human intelligence is an emergent product of neurons firing.
  • After:  Human intelligence is a product of neurons firing.
  • Before:  The behavior of the ant colony is the emergent outcome of the interactions of many individual ants.
  • After:  The behavior of the ant colony is the outcome of the interactions of many individual ants.
  • 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 arise from ant behaviors.

Another fun exercise is to replace the word "emergent" with the old word, the explanation that people had to use before emergence was invented:

  • Before:  Life is an emergent phenomenon.
  • After:  Life is a magical phenomenon.
  • Before:  Human intelligence is an emergent product of neurons firing.
  • After:  Human intelligence is a magical product of neurons firing.

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 still the same species psychology.

 

Part of the sequence Mysterious Answers to Mysterious Questions

Next post: "Say Not 'Complexity'"

Previous post: "Mysterious Answers to Mysterious Questions"

Comments (118)

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Comment author: Anonymous_Coward 26 August 2007 11:39:15PM 22 points [-]

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.

Comment author: Hopefully_Anonymous 27 August 2007 12:21:12AM 5 points [-]

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.

Comment author: Constant2 27 August 2007 12:27:49AM 12 points [-]

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, this simple mathematical model can be adjusted by plugging in values for viscosity, compressibility, and so forth. It is not exactly the same as actual fluids (the resemblance breaks down completely on the scale of molecules) but it is very close at the macroscopic scale.

Similarly, we have the concept of the "ideal gas", which is only an approximation to real gases but on a macroscopic scale a very close and useful one.

That we can vastly simplify and idealize something without losing all that much predictive power seems to be a characteristic of many so-called emergent phenomena.

Comment author: conchis 27 August 2007 01:35:34AM 10 points [-]

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".

Comment author: TGGP3 27 August 2007 02:18:03AM 4 points [-]

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 about that sort of thing, but I don't actually know much about what it is he says other than that its an important idea.

Comment author: Tiiba2 27 August 2007 02:45:00AM 3 points [-]

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 kind of AI you build, if you take it apart, it's just "switches flipping". In that debate, I maintained that intelligence does not require anything else - it emerges from switches flipping the same way that Firefox emerges from switches flipping. Both are just human names for patterns that arise in a sea of subatomic particles.

[That was one frustrating debate... Both of us were equally bewildered that the other refuses to get it.]

Comment author: Ebthgidr 31 December 2013 12:59:59AM 1 point [-]

Isn't his usage of "switches flipping" basically another 'literary genre' switch--i.e. he had attached some sort of negative connotation to the phrase which he could not conceive of attaching to intelligence?

Comment author: HI 27 August 2007 03:22:57AM 2 points [-]

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.

Comment author: Eliezer_Yudkowsky 27 August 2007 03:40:37AM 7 points [-]

Aren't superconductivity and ferromagnetism perfect examples of emergent phenomena?

Yes. So are non-superconductivity and non-ferromagnetism. That's the problem.

Comment author: Perplexed 23 July 2010 08:54:55PM 12 points [-]

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.

Comment author: DanielLC 04 August 2011 06:11:39PM 1 point [-]

Non-superconductivity means that moving electrons through it will result in the atoms moving unpredictably. It is a product of how electrons and atoms interact. It is less emergent than how, if they interact a different way, the atoms will not start moving unpredictably.

It's made up of non-superconductive subsystems in that if you take a little piece of it, that will be non-superconductive, but the same applies to a superconductor. You can't just take one atom and say whether or not it's superconductive. A current can't flow through one atom in a relevant sense.

Comment author: Perplexed 06 August 2011 05:42:57PM 0 points [-]

I think that the point is that emergence is in the mind of the observer. If the observer is describing the situation at the particle level, then superconductivity is not there regardless of the size of the collection of particles considered. But, when you describe things at the flowing-electric-fluid level, then superconductivity may emerge.

Comment author: lessdazed 06 August 2011 08:13:25PM 2 points [-]

Aren't the labels arbitrary?

Let's use sharpness.

Non-sharpness is not usually considered as an example of emergence. Because the non-sharp system is composed of smaller subsystems which are themselves non-sharp. Same goes for non-ferromagnetism. Not "emergent" because nothing new is emerging from the collective that was not already present in the components.

Let's use bluntness.

Non-bluntness is not usually considered as an example of emergence. Because the non-blunt system is composed of smaller subsystems which are themselves non-blunt. Same goes for non-ferromagnetism. Not "emergent" because nothing new is emerging from the collective that was not already present in the components.

That humans say "sharp", "blunt", "conductive", and "non-conductive" in English is due to circumstances of culture, technology, what minerals are abundant on Earth, etc. At least, I don't know the word, if there is one, for non-conductive.

To the extent "sharp" and "blunt" are not opposites, I apologize for the imperfect example.

Comment author: DanielLC 07 August 2011 12:38:35AM 0 points [-]

Conductivity isn't there either unless you describe them at the flowing-electric-fluid level.

Comment author: tmosley 08 July 2012 12:56:49AM 0 points [-]

It seems to me that emergence is the opposite of rigorous structure. Take human brain function (similar to your intelligence comment in the article). Claiming that brain function is emergent versus rigorously ordered allows you to make a prediction, namely that a child who has a portion of their brain removed will retain all or a large portion of the functionality of the removed portion, or they will not. A child with half of their brain missing would be expected to be extraordinarily impaired. A simple search of the literature should prove it one way or another.

Thus, when one says that some property is emergent, it means that it is not limited by the macro form, but by the conditions effecting the micro components from which the property emerges. This should allow for all manner of predictive ability. Of course, there are plenty of people who latch on to the word, just like there are plenty of people who latch on to the word "evolution", and don't think or use it to make predictions, and in that, your point is well taken.

Sorry for commenting 5 years after the fact, but this place seems to have at least some ongoing discussion.

Comment author: Swimmer963 08 July 2012 01:34:41AM 2 points [-]

A child with half of their brain missing would be expected to be extraordinarily impaired. A simple search of the literature should prove it one way or another.

According to this, a child with half of their brain removed can sometimes do just fine. It has a lot to do with age, though, given that children have more neuroplasticity–a fully functioning adult would probably lose a lot of their normal abilities.

Comment author: whowhowho 20 March 2013 10:50:34PM -1 points [-]

"Holistic" seems to label that phenomenon more clearly, for my money.

Comment author: Sean_Landis 27 August 2007 03:44:20AM 6 points [-]

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.

Comment author: torekp 05 April 2010 01:20:22AM 0 points [-]

Sean, that's a useful link. The "irreducible-pattern" epistemological version of emergence, described there, is one I'd heard before. It definitely wouldn't fit everything (if I had to bet, I'd bet it fits nothing).

Comment author: Eliezer_Yudkowsky 27 August 2007 03:58:08AM 5 points [-]

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!

Comment author: RafeFurst 07 March 2010 04:01:45PM 0 points [-]

Emergence is NOT the sum of the parts.

I'm curious, Eliezer, what you think of Alex Ryan's and Cosma Shalizi's definitions/formalisms of emergence?

http://www.per.marine.csiro.au/staff/Fabio.Boschetti/papers/ITprimer.pdf http://arxiv.org/pdf/nlin/0609011 http://www.cscs.umich.edu/~crshalizi/thesis/single-spaced-thesis.pdf

The both seem to be claiming that emergence is more than you are, but that could be an illusion...

Comment author: Davorak 19 May 2011 11:08:19PM *  0 points [-]

You ITprimer seems to disagree with your statement:

Emergence is NOT the sum of the parts.

ITprimer:

(3) the non-trivial interactions result in internal constraints, leading to symmetry breaking in the behaviour of the individual components, from which coordinated global behaviour arises;

(4) the system is now more organised than it was before; since no central director nor any explicit instruction template was followed, we say that the system has ‘self-organised’ ;

(5) this coordination can express itself as patterns detectable by an external observer or as structures that convey new properties to the systems itself. New behaviours ‘emerge’ from the system;

Non-trivial interactions of individual components -> Self organization -> New behaviors labeled to have 'emerged'

Where did they emerge from? The non-trivial interactions. This description runs counter to your discription "Emergence is NOT the sum of the parts." It is the sum of the non-trivial parts by the above description and a loose definition of sum.

Comment author: Zaq 21 November 2010 10:07:44PM 1 point [-]

The even/odd attribute of a collection of marbles is not an emergent phenomenon. This is because as I gradually (one by one) remove marbles from the collection, the collection has a meaningful even/odd attribute all the way down, no matter how few marbles remain. If an attribute remains meaningful at all scales, then that attribute is not emergent.

If the accuracy of fluid mechanics was nearly 100% for 500+ water molecules and then suddenly dropped to something like 10% at 499 water molecules, then I would not count fluid mechanics as an emergent phenomenon. I guess I would word this as "no jump discontinuities in the accuracy vs scale graph."

Comment author: Luke_A_Somers 09 May 2012 03:58:01PM 0 points [-]

I don't understand this comment.

Two posters had offered only positive examples. Five had offered at least one negative example in contrast to a positive example.

Comment author: blacktrance 07 January 2014 08:42:53PM *  2 points [-]

To respond to a really old comment -

Emergence does exclude some possibilities. For example, if consciousness is emergent, it means that it's not ontologically basic, it's not caused by something outside the system, and that it exists.

Comment author: TheAncientGeek 07 January 2014 09:19:23PM -3 points [-]

I could that if your epistemology is popperian, negative evidence is all you can have.

Comment author: Rip 27 August 2007 04:07:39AM -2 points [-]

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.

Comment author: mindbound 01 December 2010 04:08:28PM 1 point [-]

It seems somewhat hard to understand why are black holes being included in this list - for objects that by their definition cannot be observed directly, there certainly seems to be a whole lot of a solid observational evidence for their existence, both in the case of stellar and supermassive ones.

Comment author: Ferro 25 May 2012 05:51:02AM -1 points [-]

True. Higgs Boson anyone?

Comment author: JoshuaZ 25 May 2012 05:56:30AM 0 points [-]

That's a bad analogy. Mindbound already addressed black holes. Dark matter is however something where we know there's something weird going on, and the simplest explanation that doesn't involve completely throwing out general relativity is to posit that there's mass out there we can't see. Specific variants of that hypothesis each make different testable predictions (indeed we can even just test the general dark matter hypothesis by looking for other signs of dark matter, such as through gravitational lensing which confirms the presence of dark matter). The comparison doesn't hold.

Comment author: Sean_Landis 27 August 2007 04:32:06AM 6 points [-]
Comment author: Doug_S. 27 August 2007 04:58:48AM 0 points [-]

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 game of tennis doesn't look like an emergent property of any of its obvious components, unless you decide that tennis emerges from human brains.) OR b) X does not have a high-level model that describes the overall behavior of X without modeling the behavior of each individual component of X separately. (A list of telephone numbers is not emergent.)

People probably do use "emergent property" as a placeholder for "something caused by something else, but I don't understand how" far too often, though.

Comment author: Tom_McCabe 27 August 2007 05:07:57AM 0 points [-]

"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.

Comment author: Jeremy_McKibben 27 August 2007 05:09:52AM 2 points [-]

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.

Comment author: Anonymous6 27 August 2007 05:15:43AM -3 points [-]

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.

Comment author: bjk 27 August 2007 05:17:42AM 1 point [-]

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.

Comment author: Jadagul 27 August 2007 05:45:15AM 18 points [-]

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.

Comment author: bigjeff5 30 January 2011 03:31:00AM *  2 points [-]

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 than necessary.

The first person would brake for too long, causing the person behind him to brake for slightly longer (he isn't likely to brake for less time than the person ahead of him lest he risk an accident), which continued down the line, a chain reaction. Drivers in the lanes on either side of the initial brake chain would also begin braking as they saw people in the central lane brake, being sensibly cautious during rush hour, which would spread outward from their positions. Eventually traffic would halt, as the people ahead would have to stop completely before being able to move again.

I'm sure there was some kind of cutoff threshold regarding how long over the necessary length of time the first person has to break, but it wasn't very long, a second or two would do it during a non-jammed rush hour.

It also explains why, once a jam occurs for any reason, it is extremely slow to clear up even after the cause of the jam is long since removed.

Pretty shocking really, and certainly not an "emergent phenomena". That's why EY is against using emergence for everything - there absolutely must be a reason, and that reason cannot be "lots of stuff interacts and now we get a traffic jam!" Using emergence as an explanation encourages you to stop thinking about the problem, rather than dig in and figure out why what happened happens.

You have unexplained traffic jams - do you call it emergence or try to explain them? The rational thing to do is to try to explain them in a way that allows you to have expectations about future observations.

In other words, "Emergence" is an answer looking for a problem.

Comment author: foucist 05 March 2012 12:34:46AM 2 points [-]

"Emergence" here would be a reference to the non-linear result of the braking. Like what Henry_V said.

Comment author: bigjeff5 22 March 2012 06:37:12PM 1 point [-]

Yes, the point is to be sure you aren't using "Emergence" or "Emergent Phenomena" as stop signs. That you recognize that there is in fact a cause (or causes) for what you are seeing, and if the total seems to be more than the sum of its parts, that there is some mechanism that exists that is amplifying the effects.

Emergence is not an explanation by itself.

Comment author: Tiiba2 27 August 2007 06:06:22AM 1 point [-]

I want to say that I like Jadagul's reply

Comment author: hoffmang 27 August 2007 07:01:00AM 0 points [-]

"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 variable that leads to the observed outcome. Prove that variable or mechanism and the outcome doesn't emerge or arise - thus disproving that the system has emergent properties.

-Gene

Comment author: Alex_Wilson 27 August 2007 08:23:35AM 4 points [-]

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.

Comment author: conchis 27 August 2007 09:43:15AM 0 points [-]

"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.)

Comment author: Henry_V 27 August 2007 11:28:05AM 2 points [-]

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.

Comment author: michael_vassar3 27 August 2007 12:03:25PM 1 point [-]

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 (they are probably most of what we understand in the world, after all), just not precise long-term prediction of their configurations.

Vitalism seems to clearly constitute a "stop sign", but I'd want much more expertise before confidently asserting that proto-chemists didn't use Phlogiston to make novel predictions similar to those we would make with Oxygen. It seems to me like Phlogiston is a conflation of Oxygen and Energy similar to Newtonian "mass" as a conflation of gravitational and inertial mass, or pre-Newtonian "weight" as a conflation of weight and mass.

Comment author: Slocum 27 August 2007 12:33:38PM 0 points [-]

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). The problem of understanding intelligence was, therefore, the problem of understanding how the mind could be replicated in LISP code (or PROLOG or rule-based systems or etc).

The newer argument was that neurons have particular properties that have to be taken into account rather than ignored when attempting to understand and model intelligent behavior. And this is what is meant by saying intelligence 'emerges' from the interaction of neurons and is an 'emergent phenomenon'.

Comment author: Zubon2 27 August 2007 12:40:18PM 2 points [-]

"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 up to a Night of the Lepus situation. Non-emergent was the use of "pyreals" (gold pieces) as currency; emergent was the economy that arose using alternate competing commodities as units of exchange.

As others have stated, I usually see "emergent" used as a shorthand for something like "the whole is not predictable from the parts." No cell in your brain understands Chinese, and neither does any part of Searle's Chinese room, but the system as a whole does. Is there a better term akin to the fallacy of composition or ecological fallacy?

Comment author: HI 27 August 2007 02:06:07PM 0 points [-]

"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.

Comment author: David_J._Balan 27 August 2007 02:13:34PM 0 points [-]

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.

Comment author: Rip 27 August 2007 06:31:55PM -1 points [-]

Tom McCabe, that is not proof.

Comment author: Rip 27 August 2007 06:43:20PM 0 points [-]
Comment author: Byrne 27 August 2007 07:09:47PM 0 points [-]

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.

Comment author: Eliezer_Yudkowsky 27 August 2007 07:26:32PM 2 points [-]

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?

Comment author: rwemack 12 August 2010 12:17:36AM 6 points [-]

I think you are railing against the way emergence is used as opposed to itself as a theory.

Emergence theory can be helpful in breaking down complex systems to gain a better understanding of how they work. If the behavior of a system is dominated by a decentralized and internal control mechanism, then it is emergent. If the behavior is dominated by a centralized or an external control mechanism then it is non-emergent.

Let's take for an example the complex movement of a bee swarm. From casual observation, it looks to be a single entity that has an intelligence of itself. As a layman, upon looking at this, I could take a guess that perhaps it is magic, or the Queen bee is in full control somehow.
If somebody tells me that it is in fact emergent, then I can understand and predict the bee swarm much more accurately. I can see that each individual bee's behavior influences it's neighbor's in such a way to produce a highly complex and sophisticated system. I will be able to model and predict the swarm much more accurately than if I thought it was controlled by the Queen via pheromones, for example.
This theory also has the luxury of being testable.

Also, we can use emergence as an approach engineering problems as well. Since video games were used as an example before, let's use them again. Say we wanted to make a game where the player is being chased by formations of monsters.

One approach would be to create a computer AI to direct the monsters in a line and move towards the player. This would be non-emergent.

Another would be to create the monsters as individual objects that move towards the next nearest monster and also towards the player but at a slower rate. This would tend create clusters of monsters that charged towards the player. Now, what if had the monsters move towards the player and the next nearest monster, but away from the second nearest monster. This would tend to create lines of monsters that moved towards the player.

So, to force you to talk about emergence, I would like to propose a theory about your chosen profession, computer AI. (Caveat, I don't really know anything about it) Software AI* is non-emergent.
Neural Networks are emergent.

  • This does not count software that is modeling the human brain on a neural level.
Comment author: bigjeff5 30 January 2011 03:49:20AM 1 point [-]

Does an emergent bee swarm follow the same rules as an emergent market?

That is, can you take the rules of emergence and apply them to both as is - including only the necessary details (like how many bees or the number of stocks)?

If so, you have a testable theory. If not, you have phlogiston.

As Wikipedia describes them, "weak emergence" seems to be what the people above are talking about - that is the properties of the whole can be described/predicted by the interactions of its parts, and "strong emergence" which says the properties of the whole cannot be described/predicted by the interaction of its parts - seems to be what EY is talking about.

The notion of strong emergence, to me, seems nonsensical. I also see no formula for emergence of any kind, which suggests to me that it is not intended to make any predictions - only describe events after they occur. That sounds a lot like phlogiston to me.

Comment author: HI 27 August 2007 08:29:10PM 0 points [-]

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 understanding of the system just by getting more and more detailed information about its components. But the concept of emergence reminds us that there are certain things that we only understand when we see the system as a whole. Another thing is that it allows us to see something common in very different systems studied in different disciplines. For example, there is similarity between spinglasses in solid-state physics and neural networks. Also, you can see so-called power law in many kinds of systems. (Although power law may be another example of a concept that is overused.)

Comment author: Constant2 27 August 2007 09:07:00PM 2 points [-]

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 rather than by an elite and privileged police apparatus applying the decisions of a legislature). Similarly, a sudden rise in the price of something may not be the product of a secret cartel or of a particular government policy or politician, but may be the result of a non-obvious confluence of disparate causes. When we say that prices emerge from the marketplace rather than being set by some authority, we are denying the idea that there is some person or group who has chosen that the price should be what it is, a person who can be appealed to to change his mind, or blamed for his decision.

Comment author: Tom_McCabe 27 August 2007 09:13:10PM 1 point [-]

"Tom McCabe, that is not proof."

There is no such thing as proof. See http://www.acceleratingfuture.com/tom/?p=11.

Comment author: Rip 27 August 2007 09:15:38PM 0 points [-]

Mainstream astronomers' predictive abilities are shoddy at best. It seems as if every new observation is "surprising," or "shocking," or "baffling."

Comment author: Rip 27 August 2007 09:18:34PM 0 points [-]

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.

Comment author: bigjeff5 30 January 2011 04:01:57AM *  3 points [-]

I think you are confused about what dark matter is believed to be.

Dark Matter is believed to be non-baryonic matter. Simple as that. We have direct observations of non-baryonic matter. The largest telescopes in the world are actually designed to detect non-baryonic matter (and they succeed). They have to be buried deep in the earth because it is too easy to get noise from various types of radiation, but this is no problem, because non-baryonic matter doesn't interact with ordinary matter except in the rarest of situations.

Neutrinos are probably the most well known type of Dark Matter, and those have certainly been directly observed. Scientists are even reasonably certain of the tonnage of neutrinos produced each year by our Sun. There are believed to be other types of Dark Matter, but the nature of the particles make them extremely difficult to study. But not impossible.

The point is that expectations don't match up with reality, and the only sensible explanation is that the difference is caused by non-baryonic matter (since if it were baryonic, we'd almost certainly be able to see it). You can make predictions about what you should find based this theory, which can then be falsified.

Dark Matter is falsifiable. That's probably the most important thing to know about it.

Comment author: Sniffnoy 30 January 2011 05:19:57AM 2 points [-]

I don't think neutrinos are usually referred to as dark matter. Dark matter is whatever solves the problem of "What the hell is all the rest of this mass we can only detect gravitationally", and neutrinos don't solve that problem. And counting neutrinos as dark matter simply because they aren't baryons seems a bit silly, seeing as electrons aren't either.

Rather, I should say, dark matter is whatever solves that problem, subject to the constraint of it being a new type of matter operating essentially as usual under ordinary general relativity. Otherwise I guess it would be unfalsifiable. :) The dark matter hypothesis is really just the "Yes, GR really is correct (at large scales)" hypothesis.

Comment author: Dreaded_Anomaly 30 January 2011 05:53:06AM 3 points [-]

Neutrinos are included in the broad consideration of dark matter because they don't interact electromagnetically. "Baryonic" and "baryon" aren't quite the same; baryonic matter only needs to be composed mostly of baryons.

The dark matter hypothesis is really just the "Yes, GR really is correct (at large scales)" hypothesis.

Yes. There's "dark matter" simply defined as matter that doesn't participate in the electromagnetic interaction, and then there's the hypothesis that a significant portion of matter in the universe can be classified as such.

Comment author: Sniffnoy 30 January 2011 07:43:03AM 1 point [-]

Neutrinos are included in the broad consideration of dark matter because they don't interact electromagnetically. "Baryonic" and "baryon" aren't quite the same; baryonic matter only needs to be composed mostly of baryons.

Ah, OK. Wasn't aware of that distinction. I also failed to notice that the important consideration here is interacts electromagnetically vs. doesn't. Thanks.

Comment author: bigjeff5 30 January 2011 10:03:24PM *  0 points [-]

Yes, there are a number of hypothetical non-atomic particles that would need to exist as well, since by their very nature neutrinos have almost no mass. These additional particles have not been discovered, and discovering them would be extremely difficult.

I'd agree that it has the potential to be another phlogiston, but you've got to at least give the Dark Matter theorists a chance to falsify their theory. If it becomes a situation where new evidence comes out that DM can't predict, yet is adapted to describe DM, then you know DM is utter poppycock. There are, however, a number of avenues for experimentation, so it's certainly not the case that you can call Dark Matter a modern-day phlogiston yet.

At the same time, if DM is poppycock, then GR is necessarily very, very broken (we already know it's broken, just not for big stuff).

Comment author: Sniffnoy 30 January 2011 10:46:07PM 0 points [-]

I should note, I was not claiming it to be unfalsifiable, I was just picking nits (incorrectly). :P

Comment author: Constant2 27 August 2007 09:22:05PM 1 point [-]

"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.

Comment author: Gray_Area 27 August 2007 09:39:45PM 2 points [-]

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 than about prediction, and falsifiability. Mathematical concepts may not increase our ability to predict directly, but they do indirectly as they form a part in larger scientific predictions. Derivatives don't predict anything themselves, but many physical laws are stated in terms of derivatives.

Comment author: Rip 27 August 2007 09:41:35PM 0 points [-]

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).

This doesn't make mainstream science question the validity of gravity being the dominant force in the universe. Instead, they add hypothetical matter to the calculation. I suspect Mr. Yudkowsky's former statement that dark matter might go the route of epicycles will turn out to be correct (he probably doesn't subscribe to that anymore, I don't know).

That doesn't seem very scientific to me, but perhaps it's still legitimate since dark matter is still considered just a hypothesis.

Comment author: bigjeff5 30 January 2011 04:11:44AM *  1 point [-]

If you look through a telescope and expect to see a planet, but instead you see a planet and two moons, do you assume your telescope is broken?

That seems to be what you are advocating.

I also think you are blind to the fact that there are particles that we know to exist (not by calculation but by direct observation) that are impossible to detect with an optical or radio telescope, for the simple fact that they barely interact with ordinary matter at all. That makes counting them and adding them up through a telescope impossible (that's how they discovered the discrepancy, btw).

In light of that evidence, the most plausible explanation is that there is a big mass of this stuff floating around that we simply cannot see. We need to be sure it isn't there before we decide the theory is wrong.

Now, if there is strong evidence that Neutrinos and their ilk are not the cause of all the extra gravity, then we have to take a very hard look at General Relativity, which is what predicted the movement of the galaxy in the first place.

Comment author: Tiiba2 27 August 2007 09:50:11PM 2 points [-]

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.

Comment author: mtraven 27 August 2007 10:20:07PM 1 point [-]

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. It didn't have to be that way, so we have found an instance of emergence where we might have found something else. In AI, there are emergentist approaches like neural nets or genetic algorithms, or the old-school symbolic approach which is top-down and designed.

So it's clear that emergence is not meaningless. But you are right, it is not an explanation for anything. If you've found that a bee colony is decentralized, you still have to tease out the rules and interactions of the various agents involved.

Comment author: Constant2 27 August 2007 10:48:55PM 0 points [-]

"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.

Comment author: Jadagul 27 August 2007 11:14:42PM 6 points [-]

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. Afterwards, one of the senior delegation members approached one of his escorts: "So, who sets the price for rice in this market?" The escort was puzzled a bit, and responded, "No one sets the price. It's set on the market." And the Russian responded, "Yes, yes, I know, of course that's the official line. But who really sets the price of rice?"

The Russian couldn't conceive that an organization as complex as the open air market could have assembled itself; he was sure someone must have designed it in order for it to work. It had to have been set up. But markets and prices are an emergent phenomenon; the price isn't set by one person and doesn't have any one cause. And yet the markets function.

Similarly, a lot of people seem to have a mental model of democratic institutions that says it's a non-emergent phenomenon: if you write a constitution and hold elections, you get a democracy with the rule of law. Others (including myself) claim that democracy and rule-of-law are emergent phenomena: if they don't exist, there's no specific set of actions a central actor can take that will cause them to exist. They exist because of millions of decentralized and uncoordinated actions of individuals without specific direction. If you hold the first view, projects like the establishment of the new Iraqi government make sense: we set up a government with a constitution and elections, so it should become a free democratic state. If you hold the second view, the project is insane: freedom and democracy require millions of individual and low-level cultural shifts that can't be imposed from above, so there's no way for us to turn the nation into a democracy. My point here isn't that one view is right or wrong, although I have a firm belief. My point is that it's highly relevant to our foreign policy to ask whether democracy is emergent or not.

Usually when you say, "You can't just impose X from above," you're claiming X is an emergent phenomenon; the hallmark of a non-emergent phenomenon is that it's possible for a single actor to take a series of actions that either cause or prevent it.

Comment author: nick2 28 August 2007 01:10:40AM 1 point [-]

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 emergence is primarily useful is in pointing out that when we don't understand something, there are still alternative explanations to those that superstitiously posit a near-omniscience or that pretend to have information or an ability to model complex phenomena that one does not in fact have. So, for example, a highly improbable organism does not imply a creator, a good law does not imply a legislator, a good economy does not require an economic planner, and so on, because such things can be generated by emergent processes. To come to such a conclusion does not require that we have first reasoned out the specific process by which the object in question emerged. Indeed if we had, we wouldn't have to invoke emergence any more but rather some more specific algorithm, such as natural selection to explain the origins of species.

For this reason, I strongly disagree with the following definition

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).

Because it is just in situations where a phenomenon has a not highly reducible complexity -- where M is not fully determined by n small identical particles, or where it is but K(M') is not substantially smaller than n*K(C) -- that the idea that a phenomenon is emergent, rather than the product of a near-omniscient or near-omnipotent creator, is most useful.

I'd add that the belief that any important phenomenon is highly reducible, or that even if it is reduceable that humans are capable of undertaking that reduction, are two other species of superstition. These are just as pernicious as the related superstition of the near-omniscient creator. In many, perhaps most cases of interest we either have to be satisfied with regarding a phenomenon as "emergent" or we have to superstitiously pretend that some being has information or a capability of reduction that it does not in fact have.

Comment author: nick2 28 August 2007 01:13:49AM 0 points [-]

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 emergence is primarily useful is in pointing out that when we don't understand something, there are still alternative explanations to those that superstitiously posit a near-omniscience or that pretend to have information or an ability to model complex phenomena that one does not in fact have. So, for example, a highly improbable organism does not imply a creator, a good law does not imply a legislator, a good economy does not require an economic planner, and so on, because such things can be generated by emergent processes. To come to such a conclusion does not require that we have first reasoned out the specific process by which the object in question emerged. Indeed if we had, we wouldn't have to invoke emergence any more but rather some more specific algorithm, such as natural selection to explain the origins of species.

For this reason, I strongly disagree with the following definition

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).

Because it is just in situations where a phenomenon has a not highly reducible complexity -- where M is not fully determined by n small identical particles, or where it is but K(M') is not substantially smaller than n*K(C) -- that the idea that a phenomenon is emergent, rather than the product of a near-omniscient or near-omnipotent creator, is most useful.

I'd add that the belief that any important phenomenon is highly reducible, or that even if it is reduceable that humans are capable of undertaking that reduction, are two other species of superstition. These are just as pernicious as the related superstition of the near-omniscient creator. In many, perhaps most cases of interest we either have to be satisfied with regarding a phenomenon as "emergent" or we have to superstitiously pretend that some being has information or a capability of reduction that it does not in fact have.

Comment author: Tom_McCabe 28 August 2007 02:34:54AM 1 point [-]

"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 (eg, two matrices with different dimensions cannot be equal); - The laws of physics are invariant under coordinate transformations (no preferred coordinate system); and - Spacetime does not have an a priori curvature not affected by matter;

you are forced to use general relativity.

Comment author: conchis 28 August 2007 09:37:29AM 0 points [-]

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.

Comment author: Sean_Landis 28 August 2007 11:26:30AM 0 points [-]

"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).

Comment author: Gray_Area 28 August 2007 07:15:23PM 1 point [-]

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'.

Comment author: Jed_Harris 01 September 2007 07:36:00AM 5 points [-]

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 elements, then it is not emergent. So e.g. mass or temperature are not emergent properties.

  • If we need to analyze long chains of structurally specific causal interactions to explain the coarser grained property, then it is not emergent. So e.g. the time telling properties of a mechanical clock, or the arithmetic computing properties of a calculator are not emergent.

  • If we can compute the property as a function of the properties of the elements, and it depends sensitively on specific characteristics of their behavior and interaction, but is robust under local perturbations (i.e. doesn't depend on structurally specific causal chains), then the property is emergent. So e.g. percolation is emergent. Also we have some warrant to say that flocking, thinking (as brains do it), social interaction, etc. are emergent.

I'm not claiming these three cases cover all the legitimate positive and negative examples of emergence -- I don't think the concept has crystallized that completely yet. But I do think they answer Eliezer's challenge.

Another, less crisply defined question is whether we should be using "emergence" so defined, and relatedly, whether people are mostly trying to use it in this sense, or whether they are, as Eliezer fears, just using it as a synonym for "magic".

My own feeling is that many users of the term are groping for a clear definition of this general sort, and that they are doing so precisely to avoid having to explain a large class of phenomena by "magic".

Comment author: Eliezer_Yudkowsky 01 September 2007 07:59:00AM 0 points [-]

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?

Comment author: Jed_Harris 01 September 2007 05:17:00PM 1 point [-]

Thanks, Eliezer. Regarding your questions:

  1. Is the property objective or subjective? The coarse grained property is objective -- e.g. the largest connected component in percolation. The meta-property that a coarse-grained property is emergent is as objective as the entropy of a configuration. It is model dependent, but in most cases we can't come up with a model that makes it go away.

  2. To the extent "emergentness" is subjective, it is because it is relative to a model. So in some cases it could possibly be the result of ignorance of a better model. But we can't claim "emergentness" due to ignorance of any workable model, we can only say "I don't know".

  3. Conjecturing that a property is emergent is a guide to inquiry. It is saying "Let's look for a model of this property that's robust under perturbation of the elements of the ensemble, but where the value of the property changes dramatically due to small changes in the average value of some properties of the elements. The model will be based on some highly simplified view of how the elements interact."


Some observations about models of emergent properties:

  • We don't have a very good "toolbox" for building them yet. We're getting better, but have a long way to go before we know how to proceed when we conjecture that a property is emergent.

  • We are even weaker in the design of emergent systems. That is why even very simple designs with emergent properties, like flocking, seem so striking. This is a serious disability because we depend on systems with major emergent properties, such as markets, and we don't know how to manage them very effectively.

  • Often when people claim properties are "mysterious", we could dispell these claims if we could respond with an intuitive account of how those properties emerge. Lacking such an account, we are often vulnerable to mystification.
Comment author: Gordon_Worley 07 September 2007 01:08:00PM 2 points [-]

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 they are learning to overcome bias when in fact they are just convincing themselves that they are learning to overcome bias because they have read about it and believe it's a virtue to overcome bias. And I don't exclude myself from this group either, because although I don't feel as though I'm thinking this way, that doesn't mean I might not secretly be and I will be revealed when I discover a serious error in my behavior and beliefs.

Comment author: Tim_Tyler 27 February 2008 12:59:00PM 0 points [-]

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.

Comment author: sudo_writer 02 January 2009 05:27:00AM 2 points [-]

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 are intelligent
- The ants are not intelligent, but the colony is well-organized and they act as an intelligent body together.

Both are likely (I'm not an ant specialist) wrong. The problem is that ordinary speech emphasizes the two above interpretations, and deemphasizes the intended one below of "emergence":

- The ants may not be intelligent, and the colony is probably not well-organized. However, the simplistic rules in the ant interactions create a complex system that behaves just like an intelligent body.

That's a lot of space to save by just saying that the colony shows emergent intelligence. A similar accent describes what happens with evolution and emergent traits. The word is intended to shift the focus from the idea that "the two lifeforms developed similar traits as a /direct/ consequence of such and such conditions" to the idea that "under such and such conditions, the two lifeforms happened to develop similar traits".

The system, in this case evolution, more properly describes the mechanism than the situation, in this case the habitat. The word emergent only brings to attention that fact.

Comment author: Dave_Greene 28 April 2009 12:41:00AM 3 points [-]

The example of emergence that comes to my mind most readily is a simple observation that Douglas Hofstadter made in _Godel, Escher, Bach_ -- a book which definitely does not use "emergent" as a synonym for "magical":

In a game of Go, once there are two separate open spaces -- "eyes" -- in the middle of a connected group of stones, that group becomes invincible (because the opponent can't fill both holes with one move). There's no official rule in Go that says "Patterns with two eyes can't be captured", the rule just says that to capture a group you have to surround it completely and leave no open spaces. Thus two-eye invincibility is an emergent consequence of the rules of Go.

It's important that this new emergent rule is a significant _simplification_: once you realize that two eyes are invincible, you no longer have to do any complicated analysis about how close a two-eyed group is to being completely surrounded. It's safe, full stop (at least as long as you don't stupidly fill in the holes yourself).

The game of Go has very few rules. In practice, the two-eye invincibility "rule" is a very important and useful one, if you want to play the game well. To try to force Eliezer to talk about "emergence" or something equivalent, I would ask: where did the two-eye invincibility rule come from?

-- Okay, now, so what _isn't_ emergent? There's a another Go rule, the "ko" rule, which says you can't play in such a way as to get the exact same board position back after two moves: no capture followed by immediate recapture unless it changes the board. There's nothing "emergent" about that rule that I can think of -- it helps keep Go games from going on forever, but it has no simple-but-unexpected high-level consequences.

There are a lot of strategic patterns of play in Go that are not emergent, either -- e.g., there are no simple rules of thumb that can tell you, in all cases, whether a group with one eye or no eyes can be captured or not. Often the answer depends on a single apparently unrelated stone way over on the other side of the board. No simplifications available here, therefore no emergence.

There are many other more involved examples of emergence (and non-emergence) -- gliders and spaceships in Conway's Game of Life come to mind, and Herschels and random ash densities -- but this blog comment is too narrow to contain a good summary of them all...

Two other books that do a fine job (in my opinion) of describing the concept of "emergence" as distinct from "magic" are Cohen and Stewart's _The Collapse of Chaos_ and _Figments of Reality_.

Comment author: sboo 08 October 2012 06:12:35AM 0 points [-]

i think by 'emergence' you just mean 'implication'

Comment author: Amaroq 17 September 2009 11:52:38AM *  0 points [-]

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.

That's an example of what emergence is. Here's just as simple of an example of what it isn't.

Let's say I strapped a bunch of cars together to make a long train of cars traveling down the freeway. One car might be towing the whole train. Half of the cars might be contributing to the motion of the car train. All of the cars might be running and contributing to the motion of the train. But the motion is not an emergent property of this car-train.

Motion emerged at the level of the individual cars. Motion is also a property of the train, but that's not where the motion emerged. Motion is therefore an emergent property in cars, but not an emergent property in car-trains.

Emergent properties being "Properties possessed by the whole that the sum of its parts did not possess" basically means "This property emerged here, and not a level higher. And it was not present a level lower."

This creates a huge number of falses for a huge number of car-train configurations when testing for motion as an emergent property.

Comment author: BlackHumor 03 December 2009 04:00:07AM 4 points [-]

Most of this is specific to videogames and probably will not be applicable anywhere else:

An emergent property in the context of videogames is one the designers of the game did not intend, [more strictly: yet is not a programming error].

Excluding the possibly, since this example is ambiguous using it:

In the game Super Smash Bros, jumping is not emergent, since the designers programmed it into the game specifically.

Wavedashing [dodging into the ground so that you will be able to move while attacking] (and in fact, every single bit of strategy for every character) is emergent; it's not programmed into the game, it's just that if you put together all the intended rules of the game, wavedashing appears also.

What does "this is emergent" tell you, in this context?

It tells you first of all it's unintentional, which then tells you it has a vastly greater chance of being unbalanced or broken.

Using the stricter definition, it also tells you whatever it is profits the player in some way, because if it did not profit the player in some way it would not have emerged; someone would have found it, not used it or told anyone, and it would just fade away. (But this is only valid for emergent things when they're structured in a certain way. This part can be generalized to, say, the economy, but not, say, to traffic jams, because traffic jams are more tragedy of the commons types of things.)

It also tells you, most importantly, that it is probably not possible to know all the specific causes of this thing and instead to try wide and general causes. (i.e: "World War I happened because of a general attitude among nations that military force was a good way to solve problems." It's possible to say it happened "because Alice thought... and Bob thought... but Carol thought... and Dave thought....", but this is going to be either much less accurate or not worth the effort to make it accurate.)

What does "this is non-emergent" tell you?

There are one or more obvious specific causes that it would not be worth breaking down. (In the case of videogames, the developers, but it also works for cases like "there is a big dent in the front of my car because I crashed it into a tree" [but wait, you say, isn't that also phrasable as "because the force from the tree caused this molecule and this molecule and this molecule to move backwards"? Yes, but it doesn't matter; the only cause is still the force from the tree.])

(Finally, random other example I thought of after reading the Go example:

In chess, the position of the pieces at the beginning of the game is not emergent: there is one cause for that: because it's part of the rules of the game.

The fact that the best first move for white in most cases is pawn to e4 is emergent. Nobody wrote that into the rules of chess; it's just a consequence of the positions of the pieces.)

Comment author: pengvado 03 December 2009 07:24:19AM *  2 points [-]

What's the difference between a "programming error" and an "emergent consequence of the program as written", other than whether the programmers decide they like the result? Is it just a question of whether the rules involved can be described intuitively at the level of user-interface objects rather than lines of code?

Comment author: BlackHumor 18 May 2010 01:01:07AM 0 points [-]

Answer to your question: Honestly, I should not have included that line about errors in there at all; it doesn't need to be special cased out because most errors are emergent. (Not always; a missing negative somewhere is not emergent. But when you get to the complexity of a video game, most errors that will make it through QA are emergent.)

But also: I actually have thought about this a bit since I wrote this, and I think I can come up with a decent general definition for emergence: (don't worry, I'll get to your question in a moment)

Something is emergent when it is caused by a rule that works similarly to the second law of thermodynamics. (More specifically, the property of the second law that it isn't actually a hard law at all; it's just that when you crunch all the probabilities for all the particles involved, it is vastly more likely that the result will obey the second law then will not.)

Similarly, the ways economies develop aren't hard laws; it would be entirely possible for an economy to develop in such a way that it lets you get a free lunch. It's just that that, considering all the actors involved are out to find and take those free lunches, that you are about (using about very broadly here) as likely to find an actual free lunch as you are to find your foot has suddenly turned into gold.

(Also: I think it's a mistake to point at some finished product of laws of emergence and say it's emergent. "The economy is emergent" is just a short and slightly misleading way to say "The laws that govern an economy are laws of emergence".)

But going back to what this predicts: It predicts mainly that there is something equivalent to atoms in thermodynamics or actors in economics; some small unit of behavior that you can test for. It also predicts (in very complex systems it might not be possible to do any actual math on this, but in theory it predicts) how often the law will fail. (As noted, sometimes all you can say with confidence is "it might fail sometime"; of course if it fails OFTEN it doesn't have enough predictive value to justify keeping around.)

Comment author: Perplexed 23 July 2010 08:37:48PM 10 points [-]

Eliezer apparently travels in different circles than I do, and encounters people who use the word "emergence" very differently. Here is the kind of situation where I usually hear the word "emergence" used:


Me: Well, I think I'll build an AI that understands Chinese this weekend.

Philosopher: Build it from what?

Me: NAND gates, I suppose.

Philosopher: That's impossible. Searle proved it. NAND gates don't understand Chinese, even a little. So a collection of lots of NAND gates can't understand Chinese either.

Me: Huh? Searle and you don't get it. The understanding of Chinese is going to be an emergent property of the whole complex system.

Philosopher: <holding cross and garlic> "Emergence! Aaarghh!"

Me: Would you like me to explain the code to you?

Philosopher: No, thanks. I don't know anything about programming. But I do know that the word "Emergence" is a sure sign of messed up thinking.


In other words, I don't consider "emergence" as an inoculation against curiosity. I consider it an inoculation against stupidity. It is a claim by a reductionist that a high level phenomenon can be constructed from low-level machinery which is different in kind.

Most scientists I know use 'emergence" as I do. But I have to admit that most philosophers I know use it as Eliezer does. I guess we will just have to agree to dis- ... err, agree to miscommunicate. But I do wish that Eliezer would stop pretending that the word "emergence" has to have an explanatory function in order to be useful. It has a classificatory function. It collects together a class of models which have in common the property that naive reductionists fail to understand them. It is classification, not explanation. Putting the shoe on the other foot:


Philosopher: Your argument is fallacious.

Me: Aaarghh! "Fallaciousness" How does that explain how my argument is wrong. You are just trying to stop conversation.

Philosopher: But... But... You don't understand. Fallaciousness is not being used as an explanation.


There were some good comments on this thread, but I needed to add my own two cents.

Comment author: Kishin 14 February 2011 04:04:48PM -2 points [-]

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 frame my objection and not to patronize those who are familiar, the basic search before recent time consisted of the search for the homunculus, the little man in our head who would take in our sensory information and respond in kind. various candidates were found and rejected due to the simple fact that once you choose and individual structure to possess the properties of consciousness you must then answer how it in turn perceives and understands everything and get caught in an eternal loop of ever smaller integrative centers (because the little man in your head must also have internal structure that allows it do it's job). On top of that, even setting the recursive(?) problem aside, none of the brains structures seem to posses the property of consciousness. The eventual hypothesis submitted was emergence. Because it

Comment author: Kishin 14 February 2011 04:19:03PM -2 points [-]

Again, please help me and let me know if I am wrong, badly wrong, or very badly wrong but a little right, but Eliezer's argument seems to suffer from a couple basic flaws, the use of replacing emergence with magic being the first. It certainly serves its point to draw the parallel's between the current use of emergence and magic, but i could just as easily say, A: The car moves because of (combustion being directed into useful kinetic energy that causes parts to move and the car to run) B: the car moves because of magic as you noted, magic fails to explain everything because it is so general, and so can be compared to anything, in which lies the fallacy. You could make your point about magic and anything just as easily because magic isn't a real explanation, nor is it a good comparative point for anything. and the other point i guess is one that every college freshman knows, "wikipedia is not a liget source of anything. dont use it" though i will say that the comparisons to an engine and go earlier do not serve the purpose of those who support the hypothesis that emergence is a legitimate concept because as I noted above, the individual pieces of an engine do posses the property of motion, the oil and the fire, should you heap all the pieces of a car in a pile atop a bucket of oil and apply fire you will find that each individual piece will gain the property of motion quite rapidly and in your general direction.

Comment author: omeganaut 11 May 2011 07:45:40PM -1 points [-]

You use quarks as your one example of something that is not emergent. However, how can you prove that quarks are not a system of smaller interacting particles? String theory seems to propose that quarks can be broken into smaller pieces which are strings. Maybe its the interaction of the strings that cause the overall action of the quark?
As for emergence, the way I understand Emergence based on this post and the comments is that emergence is a result of the parts of a system interacting with one another, possibly limited to those event that were not predicted. Of course, just because someone uses this inappropriately, does not mean that its wrong. In fact, insisting that a word is terrible just because it was used wrong by some people is obviously an ad hominem argument. Just because some people use it wrongly does not mean it can't be used correctly, and replacing it with magical is simply non sequitor. I could replace every "explanation" in your article with "Magic", and it would make about as much sense. Resorting to such fallacious arguments is not the way to prove your point.

Comment author: thomblake 11 May 2011 08:03:10PM 4 points [-]

You use quarks as your one example of something that is not emergent. However, how can you prove that quarks are not a system of smaller interacting particles?

This misses the point. 'Quarks' were a stand-in for whatever particle you take to be fundamental; if there's something smaller than quarks, that does not defeat the notion that it is unhelpful to describe the action of the stock market in terms of its non-quarkness.

As for emergence, the way I understand Emergence based on this post and the comments is that emergence is a result of the parts of a system interacting with one another, possibly limited to those event that were not predicted.

In what way is this a useful concept? In particular, having not been predicted is a feature of the predictor, not so much of the event, and so attaching the adjective to the event invites thinking wrongly that 'emergence' is fundamental to the event.

insisting that a word is terrible just because it was used wrong by some people is obviously an ad hominem argument.

It is not an ad hominem argument. I know that because you club baby seals and you claimed it was an ad hominem argument; therefore, it is not an ad hominem argument. The previous sentence is an example of an ad-hominem argument. There are of course other varieties of ad hominem, but it isn't any of those either.

Just because some people use it wrongly does not mean it can't be used correctly, and replacing it with magical is simply non sequitor.

It is really not a non-sequitor. The point is that 'emergent' tells you about as much about the phenomenon as 'mysterious'. It doesn't communicate much more than "I don't understand why this happened" - as you grant above.

Comment author: omeganaut 12 May 2011 06:58:32PM 0 points [-]

Now that I have read more articles, I understand that most of my issues were due to taking the words with my definition and not hers. The result is that the article seems to be against those with different definitions of emergent, even though there is most likely more than one common definition of emergent, and no definition was previously selected as the correct one.

Comment author: thomblake 12 May 2011 10:00:49PM 1 point [-]

hers

For reference, the above article was written by this guy.

Comment author: potato 08 August 2011 10:05:38PM *  2 points [-]

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, specially if "emergent" is contrasted with "resultant".

The origin of the modern concept of emergence can be traced to the middle of the nineteenth century when realist philosophers first began pondering the deep dissimilarities between causality in the fields of physics and chemistry. The classical example of causality in physics is a collision between two molecules or other rigid objects. Even in the case of several colliding molecules the overall effect is a simple addition. If, for example, one molecule is hit by a second one in one direction and by a third one in a different direction the composite effect will be the same as the sum of the two separate effects: the first molecule will end up in the same final position if the other two hit it simultaneously or if one collision happens before the other. In short, in these causal interactions there are no surprises, nothing is produced over and above what is already there. But when two molecules interact chemically an entirely new entity may emerge, as when hydrogen and oxygen interact to form water. Water has properties that are not possessed by its component parts: oxygen and hydrogen are gases at room temperature while water is liquid. And water has capacities distinct from those of its parts: adding oxygen or hydrogen to a fire fuels it while adding water extinguishes it.

-- Manuel Delanda

Delanda is one of those anti-reductionists that I was talking about, but nonetheless I still think he gives useful and viable meanings to "emergent" and "resultant" here , though I think his arguments against reductionism are just plain silly. They leave room for reducing any "emergent property" of a whole to the interactions of its parts, so as far as I can tell his arguments leave plenty of room for reductionism.

Comment author: lessdazed 06 November 2011 07:10:21AM 1 point [-]

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 person has had his or her anticipations constrained. That person now knows that the actual explanation is one of those that don't involve the supernatural. This is only a benefit to this person because he or she had been unnaturally focused on the narrow set of states of the world in which there would be a theistic explanation of those phenomena.

Someone who believes all or many things are explained by real magic will describe something's being explained entirely reductionistically as being explained by "emergence". It is people recognizing and appreciating the mundane magic of some phenomena while believing in real magic as the cause of other things. To tell such a person that the cause is emergence is to tell them to make models at different levels and not bother looking for the supernatural as a cause.

As was said, "I don't know" can be.the best way to communicate, so too can be "emergence".

Comment author: faul_sname 10 April 2012 12:01:16AM 0 points [-]

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.

Comment author: NevilleSandiego 21 October 2012 04:26:39AM -1 points [-]

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 'emergent property', because given the laws that govern how it will fall and the initial values of the system (height and mass of object, area perpendicular to motion, density of air etc etc) I can accurately predict the object's location and momentum without having to actually drop it and see where it is.

So an emergent system is one wherein the simple base rules do not enable one to predict the large scale order or consequences (I suppose lack of order too), whereas a system which is not emergent is one wherein knowledge of the governing rules enables a prediction which can later be proven by running of the system. Prime numbers are thus an emergent phenomenon of how numbers related to each other (unless someone has found a way to predict them while I wasn't paying attention), whereas even numbers are not.

Comment author: Chrysophylax 30 January 2013 11:18:52PM 8 points [-]

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 that I can actually use. I simply do not have a good enough brain to actually run Langton's Ant. By this definition, conciousness is an emergent phenomenon (I know it's caused by neurons, but I have no idea how) but the behaviour of gases is not (I know the ideal gas law and its predictions seem reasonable if I imagine a manageable number of molecules bumping about).

By my definition, emergent is much like blue. "It's emergent!" and "It's blue!" are both mysterious answers if I asked for an explanation, but useful answers if I asked for a description.

Comment author: SoundLogic 11 March 2013 05:00:34PM 0 points [-]

I was under the impression that a property x was emergent if it wasn't determined by the set of property states of the components. IE, gravity isn't emergent since the gravity generated by something is the addition of the gravity of the parts. Intelligence isn't, because even if I know the intelligence of each of your neurons, I don't know your intelligence.

Comment author: miosim 25 November 2013 01:28:09AM 1 point [-]

Observation of individual neurons doesn't indicate they have intelligence however doe it means that intelligence of a human brain is emergence phenomenon?

Observation of individual atoms and molecules wouldn't revel any gravitation like properties either however we don't call that gravity emergence phenomena. Instead we argue that gravitation like properties of atoms and molecules are not observable. Could you conceder that we may grossly underestimate an "intelligent ability" of individual neurons?

Comment author: SoundLogic 17 December 2013 04:17:43PM 0 points [-]

What I meant by this is the gravitational influence of N particles is the sum of the gravitational influences of each of the individual particles, and is therefore a strict function of their individual gravitational influences. If you give me any collection of particles, and tell me nothing except their gravitational fields, I can tell you the gravitational field of the system of particles. If you tell me the intelligence of each of your neurons (0), I cannot determine your intelligence.

Comment author: JohnWittle 19 March 2013 03:15:37AM 2 points [-]

An excellent example of a published paper against reductionism, using "emergence" in exactly this way such that it is indiscernible from "magic", is here:

http://philsci-archive.pitt.edu/3866/1/Tilburg_submission_fin.pdf

Comment author: christopherj 04 October 2013 03:51:10AM 0 points [-]

"Emergent" is just an adjective describing an attribute. Other examples are complex, simple, generic, unique, random, predictable, valuable, politically inconvenient, unexpected, widely-known, and a few others. For example, saying "The behavior of the ant colony is the widely-known outcome of the interactions of many individual ants.", won't tell you much new about the ant colony itself, nor will it let you model it. It will tell you that ant colonies aren't successfully secretive, nor too complex for humans to understand, which technically is details about the ant colony's behavior.

Likewise, knowing that ant colony behavior is "emergent", won't let you model the ant colony. It will tell you that ants interacting in simple ways can lead to seemingly complex and perhaps unexpected behavior. But it won't tell you what rules govern the interaction of individual ants, nor of the whole colony. It does tell you that if you replaced half the ants with other compatible ants, rearranged the ants, or similar disturbances, there'd be little difference in overall behavior of the colony. You see, it is a description of the model of ant colony behavior, and not a model of ant colony behavior. It's use as an explanation or curiosity-stopper is inappropriate, but not any more so than any of the adjectives in the above paragraph.

It would be inappropriate to describe ant colony behavior as being and "emergent" property of atoms. You can't rearrange the atoms, the atoms will not continue to act like a ant colony. Conversely, rearranging and replacing cars and stock market participants, will do little to change the traffic patterns and stock market (minus a period of adjustment). As for human intelligence as an emergent property of neurons, it is a statement of fact but I do not know if it is accurate. The hierarchical structure and specialized regions, would seem to suggest more nuances than emergent behaviors are supposed to have. Neural rearrangement and replacement, on a scale of half the neurons at once, can't be done for practical nor ethical reasons, and would be expected to delete years of experience, and that without the development phase -- but it might still result in intelligence, especially if done on a fetus. I could easily see people hoping that intelligence is emergent from neurons, as it would make for a simpler model and thus cause an earlier advance in AI and intelligence related fields. I wouldn't fancy trying to figure out neuron-based intelligence if it is not an emergent behavior.

Comment author: miosim 24 November 2013 01:07:46AM *  0 points [-]

I have always been intrigued that such a complex system like a living cell, could be reduced underlying physics and chemistry. Over time, my reductionistic curiosity was eroded by holistic views that embrace emergence phenomenon as an explanation of complexity. However, eventually, I was disillusioned with the emergence paradigm, as misleading and concluded that the popular interpretation of holism ‘The whole is more than the sum of its parts,’ is profoundly deceptive if used within scientific explanation. My current view is that emergence is a perception caused by part’s properties not observable in isolated parts. These properties become observable only during interactions in the system; a system acts as ‘litmus test’ or a ‘magnifying glass’ that just reveals the parts’ properties not observable otherwise.

Regarding ant colony how much we know about individual ants to deprive them from ability of complex behavior? In my book the complexity of any system resulted from collective complexity of its elements.

The typical rhetorical argument in favor of emergence is the question: ‘Is water more than one atom of oxygen and two atoms of hydrogen?’ The intuitive respond, is yes, because in our perception, water, the way we directly experience it, is very different from an abstract theoretical model of atoms of oxygen and hydrogen. However, from a scientific point of view this question is misleading. The correct question would be: ‘Is a molecule of water more than one atom of oxygen and two atoms of hydrogen, interacting among each other?’ This time the answer is no: the molecule of water is no more that the sum of its components.

I would be interested in any example in which complexity of the system "emerges" from elements we know (or at least we believe we know) everything about.

Comment author: passive_fist 24 November 2013 02:26:20AM 0 points [-]

If anything, a single ant is a far more complex system than, say, a simple simulation of an ant colony of a computer.

Comment author: miosim 25 November 2013 01:03:13AM 0 points [-]

In this case it is obvious. However, in general a system could be less complex than complexity of its elements. We don't have agreeable way to measure complexity but for now I would argue that complexity of molecule of water (its complete physical and chemical description) is more complex than sum of those molecules in form of a drop of water. Unfortunately so far there's neither accepted approach to measure nor define complexity.

Comment author: jbay 04 October 2013 04:44:54AM 1 point [-]

I would suggest reading "More is Different", an excellent paper on the topic of emergent phenomena and the limits of reductionism. (http://www.ph.utexas.edu/~wktse/Welcome_files/More_Is_Different_Phil_Anderson.pdf).

The "More is Different" approach essentially notes that even when the basic bottom-up rules are known, they cannot be efficiently used to predict large-scale interactions. Those behaviours have to be studied as though they have their own set of rules (ie, the laws of chemistry), even though they emerge from a more fundamental set (the laws of physics). It seems to me that labelling a phenomena as "emergent" is a useful and descriptive term, which means "you need to study this phenomenon empirically to figure out its rules, because trying to make predictions based on fundamental principles won't get you anywhere".

Comment author: MathieuRoy 21 January 2014 12:36:11AM 0 points [-]

In summary: emergence is sometimes an observation but never an explanation.

Comment author: Marcus_Oz 11 November 2014 07:32:21AM 1 point [-]

Whilst I appreciate the validity of criticism offered here of the use of the word emergence (by itself) as if were an explanation sufficient unto itself - I think it a little harsh. To call it "futile" is almost acting as semantic stop sign itself for the term.

We need to take a little time to properly understand what is meant by emergence when used properly.

First that it is an observation rather than an explnation. But an observation with useful descriptive power since it observes that the phenomena under consideration is a process with properties whereby larger entities, patterns, and regularities arise through interactions among smaller or simpler entities that themselves do not exhibit such properties.

Therefore not at all properties that arise from interactions or combinations of smaller components are emergent (e.g. putting a whole bunch of magnets together just gives a larger magnetic field). So not all things arise are emergent.

So, while "emergence" is hardly an explanation - and one is obliged to look for the mechanisms that lead to the emergent behaviour - (such as how the polar hydrogen bonds in H20 give water surface tension - a property that a single H2O molecule does not exhibit) - nevertheless it's use as an observation has power since it points us to look for (and ask question about) how properties which do not exist in the sub components come to be via the interactions of the components (often multi-factor) - and also to see if there are simple factors or descriptive rules than have predictive power (e.g. flocking phenomena of birds)