This paper is an attempt to formulate elements that establish a political economy of the sustainability in both social and environmental dimensions. We mention limits of the neoclassical theory of weak sustainability, based on the hypothesis of substituability. The same limits come out a new physiocratic stream, in such a way that the procedures of internalisation of external effects are trapped in market mechanisms. Thus, starting off by assuming the concept of common good, we propose to define strong social and environmental sustainability preserving the common goods of humanity, and to use money as a public good, allowing to pay for non-marketable services.