définition¶
Ce [[qui]] est lié
test pour faire changer des choses sur la page // deuxième fois // troisième fois // 4
« The French complex systems philosopher, Edgar Morin (2008), suggests that one possible definition of complexity could be found by looking at the Latin roots of the word ‘complex’. The first meaning of the word ‘complexity’ comes from the Latin word complexus, which means ‘what is woven together’ (Morin 2008). » (Biggs et al., 2021, p. 29) (pdf)
un courant scientifique diffus et pas très clair
« In his construction of ‘a geography of complexity theory’, Thrift (1999, 33) describes ‘complexity theory’ as being a ‘scientific amalgam ..., an accretion of ideas, a rhetorical hybrid’ that has not developed from one point of diffusion. » (Biggs et al., 2021, p. 29) (pdf)
une approche ou un [[paradigme]]
« Checkland’s [[notion]] of a ‘complexity approach’ and Cilliers’s suggestion of a ‘complexity attitude’ can be linked to what Morin (2008) calls a ‘ [[paradigme]] of complexity’ or what others call ‘complexity thinking’ (Rogers et al. 2013). » (Biggs et al., 2021, p. 29) (pdf)
historique¶
caractéristiques¶
image_1760349169083_0 (pdf)
(Barroca et al., 2013, p. 8)
[[Caractéristiques]] d’un [[système]] complexe adaptatif (à comparer aux [[Caractéristiques]] d’un [[SES]] )
« [[1]]. Constituted relationally:
Complex adaptive systems are constituted relationally, which means that complex behaviour and structures emerge as a result of the recursive and aggregate patterns of relations that exist between the component parts of systems. These relations usually give rise to rich interactions within the system, meaning that any element in the system influences and is influenced by many other ones (Cilliers 1998) either directly, or indirectly via positive (reinforcing) or negative (balancing) feedbacks.
Adaptive:
Complex adaptive systems have adaptive capacities and self-organise and coevolve in relation to contextual changes. Self-organisation describes the process whereby a system can develop complex structures from fairly unstructured beginnings without the intervention of an external designer or the presence of some centralised form of internal control (Ashby 1947). Coevolution describes the recursive patterns or relations of influence that result from ongoing exchanges between components of evolving systems, practices, knowledge, beliefs and values, and the biophysical environment that mutually influence one another (Norgaard 1994; Haider et al. 2020).
Dynamic:
Complex adaptive systems are characterised by dynamic relations. In other words, the relationships in a system are constantly changing in rich and unexpected ways. These relations are mostly non-linear, which means the relationships between any two factors or processes are not necessarily uniform or proportional (Boulton, Allen, and Bowman 2015). Non-linearity can be the result of feedbacks, path dependencies, [[time]] lags or multiple [[time]] scales, which suppress or magnify processes and interactions, both internally and between the system and its environment. In CAS, non-linear dynamics also arise because the relations between variables constantly change, which renders them uncertain and unpredictable and makes these systems difficult to control (Arthur 1999). Change and not stability is thus the norm in CAS, shifting the focus from analysing stable states to analysing transient processes (the behaviour of the system in between equilibria), and from analysing outcomes to focusing on the trajectories or processes of the system. Rika Preiser et al. 36
Radically open:
Complex adaptive systems are radically open. In other words, it is the activity of the system in relation to the environment that constitutes the system itself (Cilliers 2002). This implies that we cannot clearly discern the boundary between the system and its environment, because the environment co-constitutes the identity of the system. Our definitions of systemic boundaries are thus the product of physical properties (e.g. a watershed boundary that signals a system boundary), mental constructions (i.e. where we choose to draw the line between the system and the environment (Ulrich 2000; Rajagopalan and Midgley 2015)) or the problem or research question we want to address (including the temporal and [[spatial]] scales of interest).
Contextual:
Complex adaptive systems are context dependent, meaning that the function(s) of CAS are contingent on context. Changing the context will have an impact on the [[function]] of the system. In other words, the environment suppresses or enhances possible systemic functions (Poli 2013). Moreover, the functions that we ascribe to complex systems are contingent on the level of analysis that we employ to understand a system.
Complex causality and emergence:
Complex adaptive systems are characterised by complex causality and emergence. Cause-and-effect interactions in CAS are not unidirectional or linear, but marked by complex recursive causal pathways that are non-linear and dynamic (Rasch and Knodt 1994). Emergence occurs when entities are observed to have systemic properties that are different and non-reducible to the properties of the constituent elements. It is not that the sum is greater than the parts, but rather that the system’s effects are different from those of its parts (Urry 2005). Emergent phenomena have causal agency and are real, i.e. they have ontological status (Kauffman 2008). » (Biggs et al., 2021, p. 35) (pdf)
Tableau image_1769003627513_0 image_1769003634833_0 (pdf)
(Biggs et al., 2021, p. 37)
Les agglomérations contemporaines constituent des systèmes complexes
caractéristiques d’un système complexe :
[image] (pdf)
(Barroca et al., 2013, p. 9)
## exemples
Application à la géographie urbaine
> « La ville peut être considérée comme un système composé de plusieurs sous-systèmes (Berry, 1964). Une littérature conséquente confirme l’importance de l’analyse systémique pour étudier le phénomène urbain (Pumain, Sanders et Saint-Julien, 1995 ; Sanders, 1992). Ces travaux ont déjà donné naissance à des modèles complets, souvent liés à la dynamique urbaine. » ([Barroca et al., 2013, p. 8](zotero://select/library/items/8KERS68X)) ([pdf](zotero://open-pdf/library/items/FIG5PX7R?page=9&annotation=979MJIV6))
## références
Les théories de la complexité chez les géographes (A. Dauphiné, 2003)