3.1. A few common definitions
The most commonly used definitions, found in all books that deal with systemics or the theory of systems either closely or vaguely, are as follows.
DEFINITION 3.1.– J. Forrester, in Principles of Systems and Industrial Dynamics: “A system means a grouping of parts that operate together for a common purpose […] a system may include people as well as physical parts.”1
DEFINITION 3.2.– P. Delattre, in Système, structure, fonction, évolution – Essai d’analyse épistémologique: “The notion of a system can be defined, in a completely general way, as corresponding to a set of interacting elements…”2
DEFINITION 3.3.– J.-L. Le Moigne, in La théorie du système général – Théorie de la modélisation3, is more eloquent. Simplifying his words, he tells us that the general system is the description of an artificial object “which, in an environment, given end purposes, exerts an activity and sees its internal structure evolve as time passes, without however losing its unique identity”. He insists on the constructive aspect of the thing with its modeling aspect, articulated around three hubs, that he calls a triangulation, in other words: operational (what the object does), ontological (what the object is) and genetic (what the object becomes).
Along the same lines, we can also mention Le macroscope by J. de Rosnay, with its “10 commandments” which are in fact obvious truths, as we will see ...