Complexity theory seems likely to become the key discipline of the twenty-first century. Based on the postulate which says that everything is the sum of its parts, traditional science had proceeded by first reducing the complex to make it simple. But proponents of complexity theory argue that this postulate is not always verifiable and that material aggregates as well as animal and human societies cannot be understood simply by studying their parts. French society, for example, cannot be deduced from Mr Dupond’s behaviour plus Mr Durand’s behaviour, and so on.
This book is an introduction to complexity theory. It includes definitions followed by specific examples and exercises (with solutions) to help readers familiarise themselves with the theory. The final chapters provide detailed explanations of two examples of applications of the theory: the modelisation of animal societies, specifically ants, and the neo-Darwinian theory of evolution.

It is a pleasure to read this book by a scientist who knows how to make his subject accessible to the general reader. All explanations are illustrated with examples. Many of the notions described here are already being used to understand social phenomena, and to regulate them.

Hervé Zwirn, a telecommunications engineer, is the president of Eurobios and an associate research fellow at the Centre National de la Recherche Scientifique (CNRS). A graduate of the Ecole Polytechnique, he holds a doctorate in particle physics and contributes a regular column to the magazine La Recherche. He previously published Les Limites de la connaissance (2000).