Abstract : This paper presents the main arguments from the inaugural lecture delivered at the opening of the chair "Ecological Reconversion, Work, Employment and Social Policies", established at the Collège d'Etudes Mondiales set up by the Foundation Maison des Sciences de l'Homme, Paris, in cooperation with the University Paris-Dauphine. Even though social and human sciences are reluctant to use the paradigms set up by natural sciences --be they research hypotheses or research results-- they have to answer the challenge of addressing the radical transformations natural sciences unravel. First, they have to understand how human beings have become a genuine geological agent able to destroy what makes the planet a place to live. Second, they have to ask if we can trust traditional disciplines to draw the scheme of the world we want. Third, they should contribute to the solutions to what is much more than just another crisis. The paper underlines why production has become the main expression of our societies, which have made GDP indicators their foremost criteria. It finally defines what is at stake in developing new ways to address the question of what really matters.