Structural hierarchies and domains
- The Function(s) (of the components) do not define the Behaviour (of the totality)
- There is a whole hierarchy of non-intersecting phenomenal domains (structures) that can be identified in any system:
- Physical (atoms, forces …)
- Chemical (molecules, reactions …)
- Biological (living organisms, reproduction, evolution)
See, for example, HA Simon for the standard approach to hierarchy through multiple non-intersecting domains in “biological and physical systems”:The hierarchical structure of biological systems is a familiar fact. Taking the cell as the building block, we find cells organized into tissues, tissues into organs, organs into systems. Moving downward from the cell, well-defined subsystems-for example, nucleus, cell membrane, microsomes, mitochondria, and so on-have been identified in animal cells.
The hierarchic structure of many physical systems is equally clear-cut. I have already mentioned the two main series. At the microscopic level we have elementary particles, atoms, molecules, macromolecules. At the macroscopic level we have satellite systems, planetary systems, galaxies. Matter is distributed throughout space in a strikingly non-uniform fashion. The most nearly random distributions we find, gases, are not random distributions of elementary particles but random distributions of complex systems, i.e. molecules.
- It would be rather unrealistic to select a cell as the building block if the system under inquiry is an animal’s organism. The structure of the resulting “system” would be too big and too complex to analyze
- All building elements of a system must be selected from the same (next lower) phenomenal domain (no mix and match of elements from multiple domains).
- Also, Simon’s “physical systems” – even if they may have an identifiable hierarchy – are not systems at all, in the sense that they are just structures without a purpose or behaviour, that is, they are a “system off”, not a “system for”
- Hierarchies can be observed as “Top-Down” (elements on the lower level “obey” rules from higher level) or “Bottom-Up” (properties on higher levels are generated from the lower level).
- I would argue for the later. Emergence that occurs in the next (higher) non intersecting domain of interaction is supported (generated) by the interaction of elements in the next (lower) domain. E.g. in order for chemical reactions to occur, all necessary conditions at the physical (atomic) level must be satisfied.
- The “wetness” property of H2O does not exist on the atomic level, it “emerges” only at the molecular level.
- A hierarchy identified within the same domain (system) has to do with control. Elements of dynamical systems are all grouped in just three distinct layers (regulation, control and guidance)
Hierarchy as a Tool
In the same paper, HA Simon is using the famous parable of the two watchmakers, Hora and Tempus, to promote the idea that hierarchical (and modular) structures are somehow superior to other types of structures:The watches the men made consisted of about 1,000 parts each. Tempus had so constructed his that if he had one partly assembled and had to put it down-to answer the phone say-it immediately fell to pieces and had to be reassembled from the elements. The better the customers liked his watches, the more they phoned him, the more difficult it became for him to find enough uninterrupted time to finish a watch.
The watches that Hora made were no less complex than those of Tempus. But he had designed them so that he could put together subassemblies of about ten elements each. Ten of these subassemblies, again, could be put together into a larger subassembly; and a system of ten of the latter subassemblies constituted the whole watch. Hence, when Hora had to put down a partly assembled watch in order to answer the phone, he lost only a small part of his work, and he assembled his watches in only a fraction of the man-hours it took Tempus.
- Simon will also venture further in a dubious discussion about the effects of a hierarchy on the evolution of living systems.
- It is worth mentioning here that hierarchy is not an inherent property of any machine or structure (living or not). Hierarchy is just a construct (tool) used by the observer to manage complexity while defining the system.
- A living machine is not “built of” sub-assemblies readily available in the environment as Simon would like you to believe. Cell division (growth) does not follow either Tempus or Hora’s “production” methods.
- Living “production” is autopoietic (entities are building themselves), while Simon’s watchmakers are alopoietic entities (building something else than themselves)
The Illusion of Control
- The structure of a system is defined within the boundaries it shares with the environment (between two non-intersecting phenomenal domains)
- The system’s control capabilities can not extend outside its boundaries with the environment.
- The distinction classical Cybernetics makes between control and controlled (sub)systems is not particularly useful for dynamical (state defined) systems. Such systems are closed to information as well as control
- Control is never accepted from another phenomenal domain. The “control system” is an integral part of and distributed through the system (not a subsystem).
- There are only three levels of control (functions) within every dynamical system:
- Regulation – monitoring outside disturbances and maintaining internal system states within the allowed (defined) limits that assure its integrity.
- Control (proper) – monitoring the state of regulators and setting their regulation points and boundaries in such way as to provide a proper response to excessive disturbances threatening the integrity of the regulators, and for an orderly transition to new desired states
- Guidance – monitoring trends and setting new desired states (goals) for the system to prepare for future chalenges
Note that only the “regulatory envelope” of the system has to endure the full force of the variety in the environment. The most common strategy at this level is filtration of all unwanted influences and allowing just the needed ones to affect the system.
The other two levels (functions) has to deal only with the known internal variety of the system.
- Within the system is fulfilled by signals, variable changes and state transitions; for outside communication the system has to produce messages in the form of an observable behaviour and/or artifacts.
- Information and knowledge are thus internal to the system, not a commodity that is exchanged between systems through the environment.
- The system use knowledge to extract information and than use this information to change its knowledge structure in a cyclic process of learning