The Futility of Emergence

Hmm, interesting. I've never actually realized that people used "emergent behavior" as a model or an explanation for anything. In that context, I'd always treated it as just a description, with the meaning that an "emergent phenomenon" is a "complex or seemingly complex phenomenon arising from interactions of a large number of very simple subparts," or something of the sort. Never thought of it as a model or an explanation, but just as a reasonable descriptive word. But if it is used as an attempted explanation to end discussion, then it's just functioning as a curiosity-stopper and should be questioned further.

What are phenomena that aren't "emergent"? I guess Eliezer is right when he says "a single quark". I think Eliezer makes a good case that the word is overused, and doesn't enlighten the discourse.

It might be more useful to describe things in reverse " X are the components of phenomenon Y". Such as "Neurons firing are the known components of intelligence". Because when we observe something, it can be useful to ask "what are its components"?

It contrast, everything observed IS the component of some bigger system, but it can be also useful to ask, what is the next biggest ordered system it is a part of, etc. That's where "emergent phenomena" might legitmately come in. Because an ant colony might be the next biggest ordered system that an individual ant is a part of, and that does seem like useful information.

Okay, but that's really not how I have understood emergence. It delineates a subject matter, and does so in an abstract way that includes many specific examples which are purportedly alike in some important way. But I don't think this use necessarily implies that the explanation has thereby been given. It is, rather, usually an attempt to delineate a subject matter which can be further investigated. I believe that the hope is that a general theory of emergence is possible, though my impression is that there isn't even a generally agreed-upon definition of it, let alone a commonly accepted theory.

One common element that I have sometimes noticed is that an emergent phenomenon can be idealized and a simplified mathematical model constructed of it, which is not precisely correct but which is a very good approximation. The existence of such simple and very good models is remarkable and extremely lucky for us.

For example, an actual fluid such as water is really made up of molecules that interact, but there is a simple mathematical model for fluids which treats fluids as absolutely continuous and smooth all the way down, not composed of atoms but fluid at every scale. As I vaguely recall, 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.

In line with previous comments, I'd always understood the idea of emergence to have real content: "systems whose high-level behaviors arise or 'emerge' from the interaction of many low-level elements" as opposed to being centrally determined or consciously designed (basically "bottom-up" rather than "top-down"). It's not a specific explanation in and of itself, but it does characterise a class of explanations, and, more importantly, excludes certain other types of explanation.

I would think that something like "life/intelligence is an emergent phenomenon" means "you don't need intelligent design to explain life/intelligence".

I remember when Warren Spector & Harvey Smith were going on about emergence in videogames. I think their definition was something like "a non-obvious [it may even surprise the designers] outcome of a system of rules rather than something scripted". That's a rather subjective definition but it seems to fit as well for the things that are described as "emergent" in real life. Since life is not actually a videogame but has universally valid rules, it would not be a very useful concept for that domain. I think Wolfram has written a lot 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.

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.]

Aren't superconductivity and ferromagnetism perfect examples of emergent phenomena? I'm not saying that calling something an emergent phenomenon adds any deeper understanding of it. But I think there certainly are phenomena that can be fairly called as emergent.

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

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

I don't buy the analogy between emergence and phlogiston or vitalism. Offering up "emergence!" as an explanation of a phenomenon is a category mistake, to be sure, and is a semantic stopsign when misunderstood this way.

As other commenters have noted, however, there is a proper understanding of emergence that is useful. (In philosophy, for instance, it's an admittedly sloppy but still useful term to classify different kinds of explanations of consciousness). This doesn't seem true of explanations that appeal to phlogiston or vitalism. Vitalist explanations aren't category mistakes. They're simply vacuous explanations, full stop.

Creeping into his soul, he felt the first faint tinges of despair.

After all these posts on how the strength of an idea is what it excludes, forbids, prohibits, people are still citing positive examples as proof of the power of emergence? Tell me what it isn't!

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.

Here is David Chalmer's short philosophical stab at what emergence is and ain't.

Hmmm...

What isn't emergence? Well, on a trivial level, everything observable is a consequence of physics. So, is there anything observable that does not fall into the category of "physics", and does that make the category meaningless?

I think I can come up with some things that "emergence" is not.

If X is not "emergent", then: a) X does not have a cellular automata-like model; there are no readily identifiable components of X that follow relatively simple, computable rules which generate the observed behavior of the system. (The 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.

"Black holes, dark matter and dark energy seem to pretty much fit this description. They are, after all, inventions tacked on to calculations, in order to make theory and calculation fit observations."

See http://en.wikipedia.org/wiki/Bullet_cluster for dark matter.

There are a few examples of non-emergence. For example, if we tessellate many small equilateral triangles to create a larger equilateral triangle, the resulting figure will not show any emergent properties.

Outside of mathematics, though, the concept is vague and I can't see much use for it as applied to specific phenomena.

For example, if we tessellate many small equilateral triangles to create a larger equilateral triangle, the resulting figure will not show any emergent properties.

On the contrary - the large shape emerges from all the small shapes! Isn't it wonderful? You can even get the same behavior on the higher level as on the lower level, only this time, it's emergent!

...is what an emergence advocate would say, if they wanted to claim yet more territory for their ever-growing kingdom.

If we take EY's example of a market crash, the non-emergent hypothesis is that of a random process. In other words, price action is like the action of gas molecules, or Brownian motion. To say that a market crash is an emergent phenomenon is to say that it displays more order than gas molecules bouncing off one another, which do not display emergent properties. That is not an empty distinction, as far as I can see.

Eliezer: I generally like your posts, but I disagree with you here. I think that there's at least one really useful definition of the word emergence (and possibly several useless ones).

It's true, of course (at least to a materialist like me), that every phenomenon emerges from subatomic physics, and so can be called 'emergent' in that sense. But if I ask you why you made this post, your answer isn't going to be, "That's how the quarks interacted!" Our causal models of the world have many layers between subatomic particles and perceived phenomena. Emergence refers to the relationship between a phenomenon and its immediate cause.

So, for instance, suppose I'm on the interstate and I get caught in a traffic jam. I might wonder why there's a huge jam on the road. It's possible that there's a simple, straightforward explanation: "There's a ten-car pileup a mile further on, and five of the six lanes are shut down. That's why there's a traffic jam." Obviously we could get far more reductionist— both in terms of "why is there a pileup" and "why does a pileup cause a traffic jam"—but for the conceptual level we're operating on, the pileup is a 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.

I want to say that I like Jadagul's reply

"Even better: A colony is made of ants. We can successfully predict some aspects of colony behavior using models that include only individual ants, without any global colony variables, showing that we understand how those colony behaviors [emerge] from ant behaviors."

Emerge and arise are synonyms. I'll agree with your desire to quell the potential overuse of "emergent," however as is well outlined above there is a specific testable model being proposed when emergent is used closer to correctly. That is that there is no system-wide 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

In most of the contexts in which I have seen the word "emergent used", it has signified a lack of understanding of the underlying causes of the phenomenon being described but rather than acting as a semantic stop-sign seemed to be used as its exact oppposite - as a marker for an area sufficiently interesting to be deserving of further research with a view to eventual full explanation. But perhaps I've been misunderstanding the intent of the authors.

"After all these posts on how the strength of an idea is what it excludes, forbids, prohibits, people are still citing positive examples as proof of the power of emergence? Tell me what it isn't!"

I thought I did. (Even if Jadagul expressed what I was grasping towards much better than I did.)

I'm pretty ignorant on this, but I always thought that the phrase related to complex outcomes that result from surprisingly simple systems, so that the complexity is "emergent".

One example is chaos. One can have chaotic non-linear dynamic systems and non-chaotic non-linear dynamic systems.

But, again, I could have misunderstood.

Jadagul's example seems to me to be a clear place where the term emergence is useful. Phil Goetz has given others in the past. OTOH, it still seems that in most of the cases where emergence is used as a synonym for "magic" much too often. 'Emerges from' seems to be less strong evidence for a legitimately useful term than than 'emergent', as 'chaotic' seems to be a perfect synonym for the latter.

Even in the case of 'chaotic', the tendency to use the term as a stop-sign is serious. A great deal of understanding of chaotic systems is possible (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.

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'.

"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?

"Tell me what it isn't!"

The examples I gave, superconductivity and ferromagnetism, are example of phase transitions, which only happen when there are large number of components interacting. I wouldn't call phenomena that can be explained by one or few components as emergent. So, I wouldn't call a black hole as emergent. I wouldn't call an electron and a proton making up a hydrogen atom as emergent. I wouldn't call two hydrogen atoms and an oxygen atom forming a water molecule as emergent. But liquid that is formed by a large number of water molecules is an emergent phenomenon to me. Jagadul's example of traffic jam is also a good one.

I'm pretty out of my depth here, but I'll echo what some people have said above. Before people started scientifically doing either one, would it have been obvious that a simple model would be very successful at predicting the behavior of, say, subatomic particles but would be very unsuccessful at predicting the weather? That is, it seems like there really are some phenomena where it is more true and others where it is less true that predictions can be generally and successfully made using straightforward intuitive models. It seems like the label "emergent" is just a (useful) label for the stuff where this can't be done.

Tom McCabe, that is not proof.

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

BJK is on to something: the non-emergent description of a market crash is something like "IF the Fed is raising rates and the economy is slowing down and investors are too leveraged and ... ... ... then the market will crash," while the emergence theory might define investor behavior and note that it will result in periodic booms and crashes, without special rules to govern either. That's the essence of emergence: simple universal rules rather than complex specific rules.

It might feel like junk science because it crosses disciplinary borders, but that doesn't make it invalid.

Don't y'all find it a little suspicious that so many people think "emergence" is a useful concept, yet have different definitions of what it is? (Though more important is what it isn't.)

Next stage in the gauntlet: Why is this a useful concept? Why does it increase your understanding of the universe, and your predictive power? Can you force me to talk about emergence or a concept isomorphic to it?

I disagreed Rip's opinion that black holes etc. are examples of emergent phenomena, but other than that I don't really see much disagreement about what emergence is in the comments here.

I like Zubon's description "the whole is not predictable from the parts" and "No cell in your brain understands Chinese,..., but the system as a whole does."

Why can it be useful? I can think of two possible reasons. There is a certain reductionist tendency (although I don't think being reductionist per se is bad) to assume that we get better and better 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.)

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.

"Tom McCabe, that is not proof."

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

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

Yet there are still no direct observations of dark matter.

How deep can biases run? Could it have poisoned the very foundation of modern science? I think it's something to investigate, especially considering the vast sums of money that are at stake if some mainstream theories turn out to be wrong or pointless.

"It seems as if every new observation is "surprising," or "shocking," or "baffling." "

Surely the underlying reality of this "seeming" is that a large fraction of new newsworthy observations is "baffling" etc.

I ll try a silly info-theoretic description of emergence:

Let K(.) be Kolmogorov complexity. Assume you have a system M consisting of and fully determined by n small identical parts C. Then M is 'emergent' if M can be well approximated by an object M' such that K(M') << n*K(C).

The particulars of the definition aren't even important. What's important is this is (or can be) a mathematical, rather than a scientific definition, something like the definition of derivative. Mathematical concepts seem more about description, representation, and modeling 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.

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.

Eliezer: "Don't y'all find it a little suspicious that so many people think "emergence" is a useful concept, yet have different definitions of what it is?"

That's a non sequitur. Different people define intelligence differently, so what? The fact that they don't understand intelligence doesn't mean that it isn't a useful concept.

When people actually can't agree on the meaning of a word, the signnal to noise ratio drops from using it. But in that case, instead of discarding the word, people just need to standardize it.

Emergence is an annoyingly vague concept, but that doesn't mean it's an empty one.

One meaning of emergence is "decentralized control". In a free market economy, prices and other properties are emergent from a large set of transactions among distributed agents, in contrast to a centrally planned and controlled economy. So there's something that is not emergent, or less emergent. Similarly, it used to be thought that a bee colony was controlled by the queen, but now we know that its activity is also the result of the work of distributed agents. 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.

"Let K(.) be Kolmogorov complexity. Assume you have a system M consisting of and fully determined by n small identical parts C. Then M is 'emergent' if M can be well approximated by an object M' such that K(M') << n*K(C)."

That seems to describe what I described earlier:

"One common element that I have sometimes noticed is that an emergent phenomenon can be idealized and a simplified mathematical model constructed of it, which is not precisely correct but which is a very good approximation."

I didn't, by the way, intend this as a definition of emergence, though it or something thereabouts might qualify.

Eliezer: Here's another example similar to ones other people have raised, a story I heard once, that might explain why I think it's an important and useful concept.

Supposedly, in the early nineties when the Russians were trying to transition to a capitalist economy, a delegation from the economic ministry went to visit England, to see how a properly market-based economy would work. The British took them on a tour, among other things, of an open-air fresh foods market. The Russians were shown around the market, and were appropriately impressed. 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.

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.

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.

"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.

Eliezer, I wonder whether the reason you think "emergence" isn't a useful concept is just that it seems so obvious to you that every phenomenon must fit the proposed definition that it doesn't exclude anything that's meaningful for you. (This seemed to be implied in your original post.) Even so, it can still be a useful concept as long as some people think that there could be non-emergent phenomena.

And yes, the proposed definitions of emergence are vague, but, as has already been pointed out, that doesn't imply the concept is worthless.

"Don't y'all find it a little suspicious that so many people think "emergence" is a useful concept, yet have different definitions of what it is?"

I think "bias" is a useful concept, despite the tendency for people to disagree over what regions of failurespace count as "bias." (Uh, ahem).

Some other vague concepts people disagree on: 'cause,' 'intelligence,' 'mental state,' and so on.

I am a little suspicious of projects to 'exorcise' vague concepts from scientific discourse. I think scientists are engaged in a healthy enough enterprise that eventually they will be able to sort out the uselessly vague concepts from the 'vague because they haven't been adequately understood and defined yet'.

I do think there is a good deal of commonality among the reasonable comments about what emergence is and also feel the force of Eliezer's request for negative examples.

I'll try to summarize (and of course over-simplify).

When we have a large collection of interacting elements, and we can measure a property of the collection as a whole, in some cases we'd like to call that property emergent, and in some cases we wouldn't.

I can think of three important cases:

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

You do seem to be rising to the challenge. So here's the next questions:

1) Is the property you've described objective or subjective? Are you talking about the thing itself, or a perspective you have on it?

2) If subjective, does the perspective describe ignorance, or knowledge?

3) You can define the set of left-handed red-haired Canadian women, but this set probably does not have any interesting properties that can be inferred from it beyond the definition itself. What can you infer once you say that something is emergent?

Thanks, Eliezer. Regarding your questions:

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

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

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

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

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

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

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

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.

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.

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.)

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: "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.

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

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. consciousness began to be defined as a property that did not necessarily belong to a particular structure but only occurs as a whole, and there for, is emergent. And while some people may wrongly use it as a curiosity stopper, I find it hard to believe that everybody misses the potential behind such and idea. we do not simply say "emergence" we look for other ways we might assemble such a thing and if we can reproduce it.

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.

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.

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".

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

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

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.

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.

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

"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.

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".

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

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)

Wolfram has done a lot of fantastic work on emergent mathematical phenomena. (TED talk given to a non-technical audience, but still worth watching.) One of the highly counter-intuitive things that he has worked on is computational irreducibility. Irreducible functions are ones where you have to physically run the function to find it's outcomes, and the emerging patterns. For this class of function, the emergent patterns cannot be predicted in advance.

There seems like the next step to build on older work on the halting problem, which states that some types of problems require unknowable amounts of computational power to solve. It's not possible to know whether such problems will be solvable in a finite time, or whether the program will run forever without finding an answer.

This is relevant to Yudkowsky's criticisms of emergent phenomena, because it demonstrates that emergent phenomena are not just fake explanations in these cases. The term is used to describe a specific class of mathematically defined problems, which are irreducible. These problems can't be broken down to any more simple explanations. In these instances, the phrase "emergent" isn't a semantic stopsign telling someone not to ask any more question, but rather a useful marker letting someone know that they physically can't break the problem down any simpler without breaking the rules of mathematics.

To be fair, Yudkowsky does go through great pains to specify that

It's the noun "emergence" that I protest, rather than the verb "emerges from".

But that's not quite the right distinction to make. Perhaps the noun form is more often used as a meaningless buzzword, and has been used to refer to larger and larger groups of things. Maybe you could argue that "emergence" should only be used to refer to this formal case where complexity arises from simplicity in an manner which may be impossible to predict in a finite amount of time. But, by definition, we can't actually know that any particular problem won't halt, because the test would take an infinite amount of time.

So do we just use this "emergence" word to refer to any problems which haven't yet been computed from more fundamental principles, or do we use it more generally to refer to problems where the math is just really complex? Personally, I'd lean toward the latter. The term is already in common use to describe complex systems which arise from simple ones. The term does still become meaningless if we use it to refer to slightly complex systems emerging from fairly simple ones, but it's still a useful and descriptive word for other cases. We shouldn't stop using terms like "toxins", "energy", "quantum", or "exponential" just because they have been re-purposed and watered down, so why should we do so with "emergent"?

This is very curious. I never thought of emergent as an explanation but as a property. I roughly understood it to mean that the emergent quality was transferable. That is, intelligence is a product of neurons firing but it need not have been, it could also have been generated from transistors or whatever else.

This is roughly the opposite of your ant example. Something is emergent if it can be explained/predicted with no knowledge of the lower level. A lot of properties of turing machines do not depend on the actual formalism of the turing machine.

Edit: After browsing the other comments, I realize this is something that has been brought up before. My 2 cents for whatever it is worth, I guess...

An important point that I think this raises is that answers which are otherwise not mysterious can be made mysterious if they are used as such. One good example is the way that some laypeople use "quantum mechanics" interchangeably with "magic". This doesn't invalidate quantum mechanics in its correct usage. The same could be said of emergence, which, given the comments below, seems to at least be disputed as a mysterious answer in and of itself.

EDIT: Also, this is my first post (reading through the Sequences, getting acquainted with the basics, etc.), so feedback is appreciated. I hope my contribution, well, contributes!

This is the species that thought lightning had a personality. We need a word for things happening for a bunch of tiny, seemingly unrelated reasons.

"Intelligence is an emergent phenomenon!" means that intelligence didn't happen on purpose, or that intelligence doesn't need to be intentional in order to happen. Emergence as a term doesn't add a reason for a thing, but it does rule some out.

You can also add the adjective 'emergent' into any sentence, and the product will be comparative garbage.

Saying "X is emergent" is conveying some information, if there is someone in the room that does not already know this fact. Here is an example:

Quarks are emergent.

This is not an explanation though. It is more like a anti-explanation. I just claimed that there is an underlying explanation to quarks, and then stopped. I told you to make space for an explanation, in you mental world model, and then I left you with that space empty. If you believed my statement, and if you don't already know how quarks emerges and from what, I just made an explanation shaped hole in your mind. This is not nice of me.

But at least you now know that there is an explanation to be found. When you thought quarks was fundamental, you did not even know to look, because fundamental things can not be explained, only described.

Is it ok to still post a question here? (I only discovered this blog recently. Not sure if anyone will see this.) Accepting that "emergence" is the wrong term, could someone tell me the right term for what I thought emergence referred to?

Someone mentioned water. Even if we knew a lot (everything?) about hydrogen and oxygen atoms, we would not be able to deduce fluid dynamics. There is something about water -- it's properties and behaviors -- that isn't reducible to its constituent parts in isolation, right? Scientific reductionism means we can drill everything down to its most elemental workings, but in some cases we can't drill up. We can't get to fluid dynamics (or other kinds of complexities) just by starting with hydrogen and oxygen atoms, the way we could hypothetically infer -- a la Laplace -- the position of the balls on a billiard table after the break.

What is that called?

I thought “emergence” talked about properties of a system which could not be localized to any of its parts.

It's possible that the notion of "emergence" arose as a reaction to a hard-core positivist view that there is no way for us to understand, say, biology, until we can deduce it from the behavior of individual quarks. So, possibly, the notion of "emergence" may have been invented just to say that it's actually ok to study biology even if you don't entirely understand how quarks combine into a mitochondrion. The fact that you don't have a perfect a model of how quarks lead to a mitochondrion does not forbid you to study what a mitochondrion does in a cell. You can say, there is this new thing that emerged, and I'm going to study this thing and its properties in their own right. I think that Comte's view that you ought to understand everything starting from the quarks (or, more plausibly, pure logic) and "moving up" is not too much of a strawman. I agree that "emergence" is now often used as a non-explanation though.

Unmitigated reductionism has had a detrimental effect on drug discovery and vaccine development

We simply can't anticipate or compute some interactions and effects due to the sheer complexity of living organisms in thermodynamic interaction with their environment. For instance, the experience of pain can alter human behaviour, but the lower-level chemical reactions in the neurons that are involved in the perception of pain are not the cause of the altered behaviour, as the pain itself has causal efficacy. According to the principles of emergence, the natural world is divided into hierarchies that have evolved over evolutionary time (Kim, 1999; Morowitz, 2002). Reductionists advocate the idea of 'upward causation' by which molecular states bring about higher-level phenomena, whereas proponents of emergence accept 'downward causation' by which higher-level systems influence lower-level configurations (Kim, 1999).

Have a read:

Reductionism and complexity in molecular biology

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1299179/

Some highlights

The constituents of a complex system interact in many ways, including negative feedback and feed-forward control, which lead to dynamic features that cannot be predicted satisfactorily by linear mathematical models that disregard cooperativity and non-additive effects...

An additional peculiarity of complex biological systems is that they are open—that is, they exchange matter and energy with their environment—and are therefore not in thermodynamic equilibrium...

In the past, the reductionist agenda of molecular biologists has made them turn a blind eye to emergence, complexity and robustness, which has had a profound influence on biological and biomedical research during the past 50 years.

The number of new drugs that are approved by the US Food and Drug Administration has declined steadily from more than 50 drugs per annum 10 years ago to less than 20 drugs in 2002. This worrying trend has persisted despite continuous mergers and acquisitions in the industry and annual research and development expenditures of approximately US$30 billion. Commentators have attributed this poor performance to a range of institutional causes . . . However, there is probably a more fundamental reason for these failures: namely, that most of these approaches have been guided by unmitigated reductionism. As a result, the complexity of biological systems, whole organisms and patients tends to be underrated (Horrobin, 2001). Most human diseases result from the interaction of many gene products, and we rarely know all of the genes and gene products that are involved in a particular biological function. Nevertheless, to achieve an understanding of complex genetic networks, biologists tend to rely on experiments that involve single gene deletions. Knockout experiments in mice, in which a gene that is considered to be essential is inactivated or removed, are widely used to infer the role of individual genes. In many such experiments, the knockout is found to have no effect whatsoever, despite the fact that the gene encodes a protein that is believed to be essential. In other cases, the knockout has a completely unexpected effect (Morange, 2001a). Furthermore, disruption of the same gene can have diverse effects in different strains of mice (Pearson, 2002). Such findings question the wisdom of extrapolating data that are obtained in mice to other species. In fact, there is little reason to assume that experiments with genetically modified mice will necessarily provide insights into the complex gene interactions that occur in humans (Horrobin, 2003).

Another defect of reductionist thinking is that it analyses complex network interactions in terms of simple causal chains and mechanistic models. This overlooks the fact that any clinical state is the end result of many biochemical pathways and networks, and fails to appreciate that diseases result from alterations to complex systems of homeostasis. Reductionists favour causal explanations that give undue explanatory weight to a single factor.

I think you're missing the point. To say, "life emerges from the activities of cells" or that "intelligence emerges from non-intelligence" is not simply to make empty statements devoid of meaning. The first is an assertions that "life" isn't a *thing* which one should seek to find somewhere, materially, in nature--like some yet-to-be-cataloged bird of paradise. It's a property of complex cellular processes. There are people who think that brain contains a "core self," as if it were a kind of organ. It might be so obvious to you that it's not, that you find the word emergent here to be redundant. But to say that "the self, or intelligence, is an emergent property of our brain activity" is to make it clear that it emerges as a kind of byproduct and is not a specific *thing* or essence. There are other ideas about intelligence going around. Not everyone agrees or understands how intelligence can emerge from the activities of non-intelligent "agents" or resources. So the notion of "emergence", while not explaining the details, can at least assert a stance on the matter.

So I don't see these terms as totally meaningless (nor "fun"to strip out of our language.)

"Taken literally, that description fits every phenomenon in our universe above the level of individual quarks, which is part of the problem."

Is it a good description then? I can't even find the quote you use from Wikipedia (not exactly a top notch citation in the first place). That certainly doesn't seem like a good description at all. It doesn't really even describe what emergence theorists talk about. If your entire point is going to hinge on one description, maybe shop around for a good one. Just saying.

"Now suppose I should say that gravity depends on “arisence” or that chemistry is an “arising phenomenon,” and claim that as my explanation."

Now hold on, let's take a step back. My spider senses are tingling... something certainly feels wrong about that sentence...

"Depends on"... I'm sensing an equivocation here. That certainly isn't a synonym for explanation. But let me double check my terms.

"Explain" (verb, Merriam Webster): 1.) to make plain or understandable 2.) to give the reason for or cause of 3.) to show the logical development or relationships of

That is definitely is much broader than dependence. In fact, explanations are not even mutually exclusive (I challenge anyone to give a sole explanation of a thing in the sense of explanation above). I've never heard anyone use emergence as the kind of explanation you're suggesting (im not even sure there is a such thing as an "explaination in its own right"). All I can say is give actual sources.

"A fun exercise is to eliminate the adjective 'emergent' from any sentence in which it appears, and see if the sentence says anything different"

These examples definitely sound different to me. And isn't this a bit circular? Testing the meaning of a term by seeing how you feel about it in a sentence? Is there a term I can't perform this exercise with and get the same result? The magic example is even sillier. Quantum physics sounds like magic to many people, that doesn't really tell us anything outside of how those people feel.

"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."

I certainly anticipate different models of phenomenon I consider emergent. I anticipate a different level of precision, or a different kind of precision, or a completely different unit of measure. I anticipate what kind of investigations will be more fruitful for the same effort. I anticipate the fallacies and mistakes I might make. I certainly think differently about the phenomenon. I might not anticipate the specific behavior of a thing directly, but why is that a necessary condition for explaination? A similar thing can be said about chaoticness.

"Does not each hypothesis fit exactly the same set of outcomes?"

We've jumped around from explanation to dependence now to hypothesis. These are certainly not all the same thing. I might hypothesize that a given thing has the property of emergence, and then give reasons as to why that is the case. I can hypothesize that the property of emergence has such and such consequences. In that sense the property of emergence does not fit the same outcomes. Whether "emergence" is a property we should care about in the first place is a different question.

This is so refreshing to read. I've been bothered by the "emergent phenomenon" hand waving for a while, and this post does a really satisfying job of explaining what is wrong with the term and its blind usage.