The concept of knowledge societies and the central role played by networks correspond very precisely to these new requirements of collective action, capable of mobilizing all the resources of governance and science in real time as well as in the long term, with a pluralistic international approach in mind. […] In the fields of sustainable development, environment protection and global health, the complexity of the data and the stakes involved exclude any possibility of a single response or a unique viewpoint, particularly where experts are uncertain when confronted by a new issue. The need here is to institutionalize, as it were, the fact that any question on a global scale is, initially in any case, too complex to command unanimity, even in the scientific world.