Cognitive science has often addressed situations where the collective intelligence of a population is greater than that of the individuals which make it up, for example the “swarm intelligence” of insect colonies. The aim of this article is to examine the inverse situation, where the collective intelligence of a population may be less than the intelligence of individuals. It is in this perspective that we propose to study the case of the ecological crisis. Why do contemporary humans apparently have such great difficulty in taking the necessary measures to avoid the possible extinction of their own species? In order to sketch the outlines of a reply to this question, we refer on one hand to crowd psychology; on the other, to the fact that the main contemporary system of social synthesis, capitalism, is incompatible with zero growth. However, the ecological crisis is not a fatality; this text is nothing other than an attempt, however minimal, to increase our collective intelligence concerning the conditions for the survival of our species.