SS,
This whole conversation is going so fast I can’t really follow it, but I do want to follow this sub thread with you and SS. See Larding, below. Nicholas S. Thompson Emeritus Professor of Psychology and Biology Clark University <http://home.earthlink.net/~nickthompson/naturaldesigns/> http://home.earthlink.net/~nickthompson/naturaldesigns/ From: Friam [mailto:friam-boun...@redfish.com] On Behalf Of Stephen Guerin Sent: Sunday, May 28, 2017 12:39 PM To: The Friday Morning Applied Complexity Coffee Group <friam@redfish.com> Subject: Re: [FRIAM] Any non-biological complex systems? So, what constitutes a system is arbitrary? In the mind of the beholder? I remember when we used to argue about this at The Complex. I always wanted to argue that a system is in some sense “self-bounding”. It consists of a group of entities that are interacting more intimately with one another than they are with entities outside the system. In the context of complex systems research, a system is an abstraction of a set of connected components and its boundary. The system's boundary can be defined as open, closed or isolated to flows of quantities of energy, mass, information, symbols etc. Defining information is a different thread ;-) [NST==>Ok, but the question before us is, Does the system itself “get to participate” in determining its own boundaries. <==nst] A model is the mathematical/computational formalization of the system. [NST==>This is an extraordinarily narrow definition of a model. I wish mathematicians hadn’t adopted it, because I really think it’s misleading. I wish mathematicians had talked about mathematical “renderings” or even, just simply, “mathematical formalizations”. The word, model, with all its rich associations, is just too “rich” for the use to which mathematicians put it. To me, a model, is a scientific metaphor, (e.g., “natural selection”) that affords suggestions concerning potential observations. It does so by connecting in the mind of scientists familiar phenomena with less familiar ones. Now sometimes use the word in an ambiguous sense referring simultaneously to a mathematical formalization and to the metaphor on which it is based. Thus people often speak of mathematical models of evolution, when what there are really referring to is mathematical formalizations of the selection metaphor. Similarly, the Schelling “model” is a computational formalization of a metaphor in which a neighborhood is conceived of as consisting in adjacent equally sized house lots laid out like cells on a piece of graph paper. I would urge that both mathematicians and computer folk use the word model only to refer to the rendering or conception that makes their formalization possible, not to the formalization itself. I am hoping my friend, the mathematician John Kennison, is lurking here so he can comment on this suggestion.<==nst] Is what constitutes a system arbitrary? George Box famously said "all models are wrong, but some are useful <https://en.wikipedia.org/wiki/All_models_are_wrong> ". Given that models are formalizations of systems and if arbitrary means: "based on random choice or personal whim, rather than any reason or system.", [NST==>Well, then we continue to disagree. In arguing for my position, I would argue that yours in internally inconsistent because it claims arbitrariness and usefulness at the same time. But I love you anyway. <==nst] I would say researchers use reason and systemic thought to develop "useful" system descriptions. So, system descriptions are not arbitrary. They are designed to be useful for the question being asked. No system description nor model can answer all questions - they are specifically designed for a problem at hand. Relatedly, a simulation, in the way we use it, is a single instance of a model run based on initializing a model's parameters computing next states to observe its behavior/dynamics. The phase space is the behavior of the model over all possible input states.
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