Transcript Slide 1
Gary Deckard Informatics 501 2 September 2014 Treatise on complex systems observations in behavioral sciences which discusses relevance to complex systems in the social, biological and physical sciences Four Sections to the article Frequency with which complexity takes hierarchal form Structure vs. evolution of a complex system Nearly decomposable systems Relation between complex systems and their descriptions Central theme of paper – “complexity frequently takes the form of hierarchy, and that hierarchic systems have some common properties that are independent of their specific content” (Simon, 1962) Simon defines as a system that is composed of interrelated subsystems, where each subsystem is also hierarchical and continues until broken down to elementary subsystems In a hierarchic formal organization, each complex system has a “boss” and subordinate subsystems Each subsystem is also a boss for it’s subordinate subsystems This continues until subsystems are at the lowest fundamental level Formal Organizations (business firms, governments, universities, etc.) However, not the only type of social hierarchy Families villages tribes Cell as the basic building block Cells tissues organs systems Cell nucleus, cell membrane, microsomes, etc. Span of Control/Span of a system Flat hierarchy if a system has a wide span at a given level vs. the next level Most of paper looks at hierarchies of moderate span Hierarchical physical and biological systems usually defined in spatial terms where social is mostly defined by interaction Systems of human symbolic production Books phrases chapters words Music movements paragraph parts sentence themes Parable of two watchmakers (Tempus and Hora) Both make fine watches of 1K parts each, Hora prospers, Tempus fails and loses his shop Both have to pause intermittently to answer customer calls Hora develops subassembly process allowing him to make watches much faster, Tempus must start over each time he is interrupted Simon uses as lead-in to biological evolution Numerical estimate derived from the parable cannot be used directly but the lesson is that the “time required for the evolution of a complex form from simple elements depends critically on the numbers and distribution of potential intermediate stable forms” Watchmaker parable theory assumes no teleological mechanism (complex forms can arise at random) Not all large systems are hierarchical (i.e. polymers) Most biological systems require some form of energy source The existence of stable intermediate forms on the evolution of complex forms is significant Usually trial and error, but indications of progress create selective trial and error (this is optimal) Partial results progressing towards the goal, plays the role of a stable subassembly Safe problem – cue aides in finding combination Points to the conclusion that human problem solving is “nothing more than varying mixtures of trial and error and selectivity” Two basic kinds of selectivity Various paths or combinations are tried and consequences noted Previous experience (example is reproduction in organic systems) Conclusion is that if complex systems have time to evolve they will most likely be hierarchic Interactions among subsystems distinguished from interactions within subsystems Decomposable subsystem when inter-subsystem force is negligible compared to force between subsystems (rare gas example) Nearly decomposable system when interaction between subsystems is weak but not negligible Summary 2 part proposition: “Short-run behavior of each of the component subsystems is approximately independent of the short-run behavior of the other components” “In the long run, the behavior of any one of the components depends in only an aggregate way on the behavior of the other components” Span is sometimes broad, sometimes narrow Critical consideration is the extent to which interaction between two (or more) subsystems excludes interactions with the others Physical example – gas Social example – conversation vs. mass communication Hierarchies have property of near decomposability Intra-component linkages are generally stronger than inter-component linkages The fact that many complex systems are nearly decomposable and hierarchic enables us to understand and describe them Other complex systems that are not hierarchic may escape observation and may cause us to believe that most complex systems are hierarchic Hierarchic systems generally contain redundancy Usually composed of a few types of subsystems in various arrangements Are often nearly decomposable By recoding, the redundancy in a complex system can be made understandable and clear State description – characterize the world as sensed (pictures, blueprints, most diagrams, chemical structural formulas) Process descriptions – characterize the world as acted upon (recipes, differential equations, equations for chemical reactions) Distinction between these two descriptions defines the “basic condition for the survival of adaptive organisms” Evidence that human problem-solving is a form of means-end analysis that discovers a process to reach a goal (find the process to get from an existing state to a desired state) Evolution of complexity does not imply selfreproduction (e.g. atoms of high atomic weight and inorganic molecules) If the description of an object is sufficiently clear and complete, the description provides the necessary information to reproduce the object Well-known biology generalization Individual organism in its development goes through stages which resemble ancestral forms Shows that one way to solve a complex problem is to reduce it to a previously solved problem, this may lead to a solution to the new problem Concept be applied to problems outside of biology Partial recapitulation may be the best route leading to advanced knowledge “How complex or simple a structure is depends upon the way we describe it” “Most complex structures are enormously redundant”, this redundancy can used to simplify its description Dynamic laws, expressed as differential or difference equations have played a major role in the development of modern science The correlation between state and process description is fundamental to the capacity of an adaptive organism to act on its environment Simon, H.A. [1962]. "The Architecture of Complexity". Proceedings of the American Philosophical Society, 106: pp. 467-482.