The article aims to discuss the alleged rationality of the defenders of the current model of accumulation by suggesting the need for a debate at the level of ideas. The ideas of limits and sustainability are presented as strong concepts to confront the imaginary constructed by the idea of infinite abundance. Then the state of art of the debate over the concept of sustainability is presented: its various interpretations and the political conflict which lies behind them. Naess�s distinction between superficial and deep ecology along with Riechmann�s negationist alternatives regarding the environmental problem arealso stated. The article also briefly presents some of the main propositions to confront the environmental crisis: green capitalism, dematerialisation, decreasement, biomimesis, Sumak Kausay, ethics of consumption, the downing principle and ending with the proposal of the necessary articulation between solidarity economy and sustainable development as well as with the identification of which should be the essential elements of both proposals. The article concludes by outlining some of the key values to which our present culture should evolve.