Cindynics, The Science of Danger

Appendix 2Notions of Interaction and Complexity

A2.1. Preamble

“Life is a relationship among molecules and not a property of any molecules” noted the eminent American chemist and physicist Linus Pauling.

Morin, in La méthode, Volume 1: La Nature de la nature, adds, “the organization in systems produces unknown qualities or properties of parts conceived in isolation: emergences”.

These types of relationships are called interactions, and emergences are properties of complexity.

A2.2. Notions of interactions

An interaction is a reciprocal action or influence between two or more elements of a system or different systems. It has a change effect that participates in the evolution of the system:

• – either on the scale of the integration of elements (for example, pollinating insects that co-evolve with flowering plants);
• – or by creating new properties through the emergence effect (for example, mayonnaise).

This notion of interaction can be used in various disciplines (biology, chemistry, mathematics, physics, medicine and social sciences).

It is therefore inevitably used in the context of risk control, where dreaded events “emerge” from the interactions between the various elements that constitute our socio-technical systems.

However, in traditional risk management, instead, we have tended to favor the study of causes linked to technical interactions whose actions retain a proportionality between them (linear dynamics).

However, as our socio-technical systems are an assembly of ...