"A system for which there exists a means of decomposing it into parts or subsystems" (P.H. ROOSEN – RUNGE, 1966, p.13).
ROOSEN – RUNGE adds: "Only decomposable systems can have a structure" (Ibid).
While this is evident, this way to present the concept is ambiguous: A non-decomposable system is no system at all, but only an element… if there exists somewhere a non-decomposable element! H. SIMON's view of near-decomposability is more precise.
He considers interactions between elements at different levels, which implies that decomposable systems must, in principle, be hierarchic. Furthermore, at each level he observes the interactions between elements, that can be strong, moderate or weak (or very active, frequent, or rare). He does this by using matrixes.
He also links the evolutive capacity of systems to the frequency of the existence of stable combinations between elements in defined neighborhoods. (This is quite similar to KAUFFMAN's "frozen cores"). For him the necessary time for a great system to spontaneously self-organize from its elementary components grows geometrically in relation to the number of the components. This is why evolution is a phenomenon hierarchized in time. (see "Hora and Tempus" parable).
A curious consequence, also stated by SIMON, is that, if a hierarchy of subsets exists, in a more or less constant quantity, then the time necessary to constitute a system of n elements will grow only in relation to logn.
Thus, hierarchy provides systems with an evolutive advantage.
SIMON also observes that, when climbing from lower to higher hierarchic levels, the interactions between elements become ever weaker. He gives as an example that, while the energies of typical covalent atomic links are in the bracket of 80 to 100 K. calories per mole, the hydrogen energetic links in organic molecules are only about 10K. calories per mole, and so on. According to SIMON this weaker linking energies at higher hierarchic levels allows for transformations at the higher level without disturbances at the level of the lesser subsystems, i.e. guarantees global stability (SIMON, 1977 – 1990).
- 1) General information
- 2) Methodology or model
- 3) Epistemology, ontology and semantics
- 4) Human sciences
- 5) Discipline oriented
To cite this page, please use the following information:
Bertalanffy Center for the Study of Systems Science (2020). Title of the entry. In Charles François (Ed.), International Encyclopedia of Systems and Cybernetics (2). Retrieved from www.systemspedia.org/[full/url]
We thank the following partners for making the open access of this volume possible: