Emergence

{{Sciencenav}}
{{cquote|The whole is greater than the sum of its parts.|||[[Aristotle]]}}
'''Emergence''' is a name given to a wide variety of phenomena where the appearance of complexity arises out of very simple rules. An important aspect is the ''multiplicity'' of these simple rules; one or two instances of a rule won't produce any emergent phenomena, but hundreds, thousands, or millions of instances, working in concert, will.

Emergence is a statement about our understanding, not about the [[Universe]], which is only made of [[quark]]s and [[lepton]]s interacting according to the four forces. This applies to our beliefs and understanding itself (or, say, {{wpl|Illusion|illusions}}), as well as to you reading this sentence. (Some people, skeptical of emergence, push this further to complete "eliminative reductivism", although, if they are right, then, paradoxically, they are not right and do not even exist at all — fundamental stuff enables, not replaces our everyday world.)

==Weak and strong emergence==
Emergence is classified into either "weak" emergence or "strong" emergence. The distinction between the two is clear, but sometimes quite subtle. 

===Weak emergence===
This is also known as "reducible" emergence. In this form, the emergent phenomena can be traced back to the individual components. This is related to a [[reductionist]] [[philosophy]]; you can predict and observe higher level phenomena just by looking at individual components.

===Strong emergence===
Also known as "irreducible" emergence (but certainly not to be confused with [[irreducible complexity]]), this states that the phenomena cannot be reduced to the individual components. Instead, the emergent phenomena are traced back to the interactions between the multiple components, so quite literally ''cannot'' be predicted in any sense by looking at the components on their own.

An example from [[mathematics]]: [[Gödel's incompleteness theorems]] assert the existence of a proposition within any formal system of sufficient complexity that basically says "I can't be proven in this system." The statement is true; it can't be proven within the system. That is, working within a system, looking only at the individual components, you see a proposition that cannot be proven true or false; yet looking on a higher level, at what the proposition ''means'', allows you to "prove" (not in a technical sense!) that it is true.

===Level===
[[File:Gospers glider gun.gif|thumb|right|A "Gosper glider gun" in the Game of Life: an example of simple rules producing "gliders" ''ad infinitum'']]
Emergence is often seen when a system is observed at a higher [[Levels of analysis|level]]; i.e., you look at ''more'' of the same thing. A simple example can be found with the [[Cellular automaton|cellular automata]] found in Conway's ''Game of Life''. Although each cell operates under very simplistic rules, large structures with apparent complexity that operate on their own rules appear when the automata gather together in large numbers. At a distance, the huge "gliders" and "puffer trains" observed in ''Life'' look like living entities that move across the board, seemingly following their own behavior, but on closer inspection, they still operate by the same rules as far more simplistic structures.

The concept of gameplay is based around emergence and cannot be designed into the [[game]] directly. Simple rules interact to create a near-infinite number of possible outcomes (game states) and a variety of different options to the players, and the analysis and execution of these options forms what is known as a {{wpl|metagame||.}} The games {{wpl|Chess}} and {{wpl|Go (game)|Go}} are prime examples. The analysis of metagames<ref group=note>Yes, that is metagames in the plural sense — the metagames of multiple different games, and the very concept of a metagame.</ref> and their development, and how this relates to decision-making and the optimization of outcomes, in turn gives rise to [[game theory]].<ref group=note>This is admittedly something of an oversimplification, as game theory is not limited to games in the sense of artificially-constructed rule-constrained goal-seeking for the purpose of entertainment.</ref>

===Scope===
[[File:Möbius strip.jpg|thumb|right|A Möbius strip made from paper]]
In another example, the Möbius strip can be said to have emergent properties. The strip, often used as a representation of [[infinity]], has only one side and one edge, but cutting it up or looking at a sub-section of the strip shows a two sided object with multiple edges. This is an example of ''emergence coupled to scope'' (as opposed to level, above) as any subset of the Möbius strip doesn't have the same scope as the whole thing taken together, with the characteristic twist that gives the Möbius strip its features.

==By emergence or by design?==
Emergence is the naturalistic explanation for what many people take to be [[Intelligent design|design]] in the Universe. The [[cell]], for instance, appears to be a massively complex system where everything works in close harmony to keep this small unit of [[life]] operational. The [[human]] body, or any living organism for that matter, operates as a collection of cells and appears to do miraculous things that would not be suggested just by looking at an individual cell.<ref group=note>It is [[#Strong emergence|an important point]] that emergent phenomena cannot be derived, in practice, from knowing the basic underlying simplicity ''[[a priori]]''; you must observe how it works or run the simulation to see how it behaves, then determine rules [[Empiricism|empirically]].</ref> The apparent complexity of the universe is interpreted as "design" [[Argument from personal incredulity|mainly due to]] [[incredulity]] that natural laws could do something as complex as life &mdash; especially the cell, [[Irreducible complexity|the complexity of which has been abused by intelligent design advocates]] for decades. 

Yet, if you take life apart and look at it close up, it's all [[molecule]]s obeying the laws of [[chemistry]], made of [[atoms]] obeying the laws of [[physics]]. The motion of [[proteins]] in a cell react just as they would as individual and separated components in a chemistry lab;<ref group=note>Even [[enzyme]]s, the facilitators of cellular processes, do not enable impossible reactions; they are {{wpl|Catalyst|catalysts|,}} physically manipulating molecules to drive chemical reactions to occur in conditions that would normally be suboptimal.</ref> it's only when it's brought together in the scale and context of the cell that these proteins do something "special". The complexity of the cell emerges from the biochemistry of the individual proteins that make it up, which in turn emerge from the basic laws of how atoms connect and react at the molecular scale. This is often an uncomfortable thought for people of a spiritual persuasion because at no point in this chain does a [[magic]] spark of life get injected &mdash; life is merely emergent from simple rules. Our apparent complexity, [[consciousness]], and organisation is described as an emergent phenomenon that comes when you combine billions of atoms working together in a very specific fashion to perpetuate and regulate a chain of chemical reactions.

==See also==
*[[Levels of analysis]]
*[[Abiogenesis]], the same thing in the [[reality|real world]].
*[[Cellular automaton|Cellular automata]], an example of emergent order from [[chaos]] by simple rules.
*[[Unguided evolution]]

==External links==
*[http://www.emergentuniverse.org/#/home Emergent Universe]
*[http://plato.stanford.edu/entries/properties-emergent/ Emergent Properties in Stanford Encyclopedia of Philosophy]
*[https://www.youtube.com/watch?v=wJyUtbn0O5Y The Inner Life of the Cell] — A video that shows the complexity of the biomolecules within human cells.
*[http://www.fractal.org/Fractal-systems.htm Fractals] are an example of an emergent system, and [http://www.miqel.com/fractals_math_patterns/visual-math-natural-fractals.html pretty as well.]
* [http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.155.793&rep=rep1&type=pdf Emergent Phenomena only belong to Biology by Hugues Bersini and Christophe Philemotte] is an accessible  introduction to emergence.
*[http://complexsystems.org/publications/pdf/emergence3.pdf The re-emergence of "emergence": A venerable concept in search of a theory. Complexity, 7, 18-30] is another accessible paper on the history of the term "emergence".

==References==
*''[http://books.google.com/books?id=lic72KLZq-0C&q=godel+escher+bach&dq=godel+escher+bach&hl=en&src=bmrr&ei=h22TTpmFAYLb0QHOrt0y&sa=X&oi=book_result&ct=result&resnum=1&sqi=2&ved=0CC0Q6AEwAA Gödel, Escher, Bach: An Eternal Golden Braid]'' by [[Douglas Hofstadter]]
*''[https://newbooksnetwork.com/christian-list-why-free-will-is-real-harvard-up-2019/, Why Free Will is Real]'' by Christian List

==Notes==
{{reflist|group=note}}

[[Category:Evolution]]
[[Category:Science]]

Categories: Evolution, Science