The End of ( Traditional ) Emergence : Introducing Reactive Emergence
exist without — and is therefore dependent on — the notes of which it is composed . However , the arrangement of the notes is an independent property . In this sense , the whole is more than the sum of its parts . When I talk about a property being independent of the properties of its constituents I am referring to properties that depend on and are brought about by the organization of the constituents .
2.3 What is Emergence ?
Why do the interior angles of a triangle sum to 180 °? The answer , of
course , is that this property follows from the axioms of Euclidian geometry . If a physical implementation is true to its abstract specification , 8 its interior angles sum to 180 °. I suggest it is fruitful to see emergence in terms of specifications and implementations and , as we will see , in terms of scientific models and realizations .
Turner ( 2014 ) defines a specification as “ correctness criteria ” and an implementation as “ a realization 9 of a specification .” He also distinguishes between two kinds of abstract descriptions : a specification and a scientific model .
In computer science , the specification determines the correctness of an implementation . In science , things are reversed . [ The physical object determines the correctness of the scientific model .] ... When things go wrong , the blame is laid with the implementation in computer science and with the model in science .
When a property description ( a model or a specification ) matches the embodiment ( e . g ., a heart or a program ), we say ( a ) the model correctly captures the heart ’ s behavior , but ( b ) the program correctly implements the specification . The ( concrete ) realization and the ( abstract ) specification are the givens ; the ( abstract ) model and the ( concrete ) implementation are derived from them . 10
We can characterize emergence in these terms .
• Naturally occurring emergence occurs when nature happens to realize properties that are independent of the properties of the elements that play a role in the realization . We recognize the emergence of this sort by developing a model of the emergent properties . The model may be scientific ,
8 Steven Weinberg suggested the triangle example in Carroll ( 2012 ). His point was that the implementation details are crucial and that they depend on the laws of physics .
9 A word about the terms implementation and realization . In the functionalist and computer science literature ( including Turner ) implementation and realization are often used ( interchangeably ) to refer to a generally physical — software being the exception — embodiment of something that satisfies a specification . An often-implicit difference between implementation and realization is that to implement tends to suggest intentionality whereas to realize does not . System developers ( deliberately ) implement a given specification . Nature realizes some ( apparent ) functionality , but with no intentionality implied .
10 On the other hand , once some functionality becomes important to survival , evolution tends to produce better and better realizations of that functionality . See Denny and McFadzean ( 2011 ).
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