Operationalizing Sustainability

2Sustainability in Complex Systems

2.1. Preamble: theories of interconnected systems

Conceptually, our real world is described by theories and laws, which are primarily devoted to special cases or approximations of the universal world. Regarding the study of systems’ behaviors, for example, it uses the concept of uncertainty or randomness; we will divide this into “wise” or “wild” randomness, as expressed by B. Mandelbrot [MAN 89]. However, the current logic of these approaches is often based on some so-called “comfortable” properties:

• – the basic values, characteristics and references of an unexpected phenomenon are always assumed to be well identified. They are associated, as in any statistical distribution, with parameters such as mean, standard deviation, etc. This results from a given assumption, a predefined model or even a predetermined outcome;
• – the process is also predefined through a model, and adjusted due to successive approximations or optimizations. The programmable function provided by the process is mostly a program of order “1”; indeed, we often consider that the “local” evolution of the system is a linear and continuous one. Similarly, the gap between two successive values remains low. Finally, such systems evolve toward stable equilibria.

However, we see that random phenomena attributed to chance are often due to hidden mechanisms we cannot yet explain: so, they are unpredictable in the current state of our means and knowledge. In nature, the world around ...