[Athena] Annonce éminaire D. Batten sur l'évolution

[Jean-François Picard <jean-francois.picard AT mouchez.cnrs.fr>]

De : Peggy Tessier <peggy.cardon AT univ-paris1.fr>

La prochaine séance du séminaire général de l'IHPST aura lieu le jeudi 19 novembre de 11h à 13h dans la grande salle de l'IHPST. L'orateur en sera David Batten, CSIRO Centre for Complex Systems Science, Australie, et le titre de son exposé est : "Demystifying emergence and evolution". 

Résumé :

Many of the most interesting exemplars of emergence are complex, highly evolved and self-organizing.  For any notion of emergence to be useful, however, it must be definable in a clear, unambiguous manner.  Several authors (e.g. Bar-Yam, 2004; Ryan, 2008) have argued that the conventional account in terms of level and hierarchy does not meet this criterion. The primary problem with levels in a hierarchy is that such apparent levels may not really exist. More often than not, they are artificially imposed on the world by the way we structure our thoughts or observations. As such, Ryan (2008) has proposed an alternative framework based on */scope/*, */resolution/* and */state/*. This alternative framework is fundamentally */spatial/*, since scope is defined by a spatial boundary and resolution is defined as the finest spatial distinction between two alternative system configurations.

Other authors (e.g. Bar-Yam, 2004; Fromm, 2005) have proposed classification systems that distinguish between simpler and more complex forms of emergence. Fromm’s taxonomy is interesting because it is based on different feedback types and the structure of cause-and-effect relationships. Also, it aligns closely with the classification of Cellular Automata (CA) proposed by David Eppstein

. Causal relationships are a natural focus for all forms of emergence, because the cause is normally the unclear point: */emergence is an effect or an event where the causes are not immediately visible or apparent/.*  Therefore, questions about emergence are inevitably posed as questions of causation – the search for a hidden cause that produces an apparent effect. 

Fromm’s classes of emergence can be classified roughly into four types:

*Type I – *contains no feedback at all, only “feedforward” relationships

. *Type II – *contains simple feedback – positive or negative. *Type III* – contains multiple feedbacks, learning and adaptation

. It* *appears in systems with many feedback loops or in complex adaptive systems with intelligent agents. *Type IV *emergence is characterized by */multi-level/*/ /emergence and a very large amount of variety in the created system, i.e. the number of possible states of the emergent system is enormous (due to a combinatorial explosion). *Type IV* emergence is responsible for structures so complex that they cannot be reduced, even in principle, to the direct effect of the properties and laws of their elementary components.

Fromm portrays the relative influences of self-organization and evolution on the different types of emergence in the following way:

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With increasing complexity, from simple emergence (i.e. Type I) to weak emergence (Type II), emergence with multiple feedbacks (Type III) & strong emergence (Type IV), he suggests that the influence of evolution gets stronger while that of self-organization gets weaker. This perspective assumes that self-organization and evolution are unrelated. 

In a recent paper (Batten, Salthe and Boschetti, 2008), we tackled the question of whether (1) natural selection drives evolution; (2) self-organization drives evolution, or (3) natural selection and self-organization are complementary aspects of the evolutionary process. We argued that these three views may not be mutually exclusive, since each may apply to different stages of development of complex systems, affecting their emergent properties in different ways. What emerged from our analysis was a more encompassing view: that */self-organization proposes what natural selection disposes/*/./

In this paper, I shall elaborate further on the relationship between types of emergence and the evolutionary process (via natural selection and self-organization). Particular attention will be paid to examples in which top-down and bottom-up feedback effects co-exist and co-evolve. Some carefully chosen territorial examples will shed light on more interesting cases of emergence that are complex, highly evolved and self-organizing.  

References:

Abbott, R. (2006): “Emergence explained: abstractions”, /Complexity/ *12*(1): 13-26. Batten, D., Salthe, S. and Boschetti, F. (2008): “Visions of evolution: self-organization proposes what natural selection disposes”, /Biological Theory/ 3(1): 17-29.

Bar-Yam, Y. (2004): "A mathematical theory of strong emergence using multi-scale variety", /Complexity /*9(*6*)*: 15-24.

Fromm, J. (2005): “Types and forms of emergence”. http://arxiv.org/ftp/nlin/papers/0506/0506028.pdf

Holland, J. (1998): /Emergence: from chaos to order/, Oxford University Press, 1998.

Ryan, A. (2008): “Emergence is coupled to scope, not level”, /Complexity/ *13*(2): 67-77.

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