The Futility of Emergence
Translations of this material:
- into Russian: Не рассчитывайте на волшебство. 48% translated in draft.
Submitted for translation by bt_uytya 31.03.2012
The failures of <a href=«/lw/is/fake_causality/«>phlogiston</a> and <a href=«/lw/iu/mysterious_answers_to_mysterious_questions/«>vitalism</a> are <a href=«/lw/im/hindsight_devalues_science/«>historical</a> <a href=«/lw/il/hindsight_bias/«>hindsight</a>. 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. (<a href=«http://en.wikipedia.org/wiki/Emergence«>Wikipedia</a>: «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 <a href=«/lw/iu/mysterious_answers_to_mysterious_questions/«>mysterious answer to a mysterious question</a>. 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:
<ul> <li>''Before:'' Human intelligence is an emergent product of neurons firing. </li> <li>''After:'' Human intelligence is a product of neurons firing. </li> </ul> <ul> <li>''Before:'' The behavior of the ant colony is the emergent outcome of the interactions of many individual ants. </li> <li>''After:'' The behavior of the ant colony is the outcome of the interactions of many individual ants. </li> <li>''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. </li> </ul>
Another fun exercise is to replace the word «emergent« with the old <a href=«/lw/iq/guessing_the_teachers_password/«>word</a>, the <a href=«/lw/ip/fake_explanations/«>explanation</a> that people had to use before emergence was invented:
<ul> <li>''Before:'' Life is an emergent phenomenon. </li> <li>''After:'' Life is a magical phenomenon.</li> </ul> <ul> <li>''Before:'' Human intelligence is an emergent product of neurons firing. </li> <li>''After:'' Human intelligence is a magical product of neurons firing. </li> </ul>
Does not each statement convey exactly the same amount of knowledge about the phenomenon's behavior? Does not each hypothesis <a href=«/lw/if/your_strength_as_a_rationalist/«>fit exactly the same set of outcomes</a>?
«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 <a href=«/lw/iu/mysterious_answers_to_mysterious_questions/«>sacred mystery</a> 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 <a href=«http://yudkowsky.net/virtues/«>shackles</a> of settled science, they get up to the same shenanigans as their ancestors, <a href=«/lw/i7/belief_as_attire/«>dressed up in the literary genre of «science«</a> but still the same species psychology.