This is often the case. There would therefore be no hope and “sustainable development” would be just a chimera invented by a desperate civilization. Perhaps the point of view at the origin of these positions is simply unsuited. The global solution is perhaps not the sum of the optimal answers to each of these numerous subquestions. Perhaps the interactions between these interrogations are in fact primordial? They can however only be taken into account if we treat the sub-problems in an isolated manner… . An epistemological parenthesis is necessary. Treating the question of sustainable development requires an original approach, different to that of the classical analytical approach, which is unsuitable. The systemic approach was invented precisely because of the need to treat subjects of great complexity. To give it a clear and concise defi nition seems diffi cult. It is however possible to defi ne it more clearly by comparing it to the analytical approach used in many scientifi c subject areas. The classical analytical approach consists of restoring a system to its simplest elements[DEROS77], to analyze in isolation their properties and the laws which govern them in order to reconstitute, by adding them together, the properties and the system laws. This type of approach has enabled science to progress for many centuries. Great scientifi c domains such as chemistry or electronics have been constructed via this analytical approach due to the management of elementary properties and their additivity. The principal limit of this approach resides in its insuffi ciency with regard to the complexity; when models-formed by the addition of the behavior of principal elements-are too far from reality, when interactions between elements become more signifi cant. It would seem in actual fact incongruous, for example, to try to understand in an analytical manner how the contemporary world economy functions, given the huge quantity of elements and the interactions complex and essential. A system is “a group of elements in dynamic interaction, organized according to an aim”[DEROS77]. Contrary to and complementary to the analytic approach, the systemic approach fi rst considers the complexity and the dynamics of the whole system. The interactions
between elements become essential. During a study of a “natural” ecosystem for example, a laboratory analysis of an insect species of course will give certain information. But it however will remain insuffi cient to understand the behavior of the insect “in situation”, in amongst the other species. If, on the other hand, the species is studied within its ecosystem in connection with the other species, more can be understood. The manner in which it camoufl ages itself or in which it moves around can for example be explained by the interactions which it will have with its prey and predators. Table 3 highlights the fundamental differences between the two approaches.