Planning and sustainable development in the twenty-fist century

Although fallen into disrepute in the 80s, the use of planning has been put back on the agenda, with the 2008 financial crisis, but also with the growing recognition of the inability of nowadays societies to tackle their long?term development challenges. Thirty years later, I follow the Malinvaud?Chakravarty’s line of reasoning by questioning the form and usefulness of collective planning. I first recall the main historical arguments about its advantages and disadvantages compared to the other institutional arrangements available for promoting a collective coordination. I pick insights from different fields of economic thoughts (expectational coordination, public economics, political economics, collective decision making and planning). I examine the practice and usefulness of the modelling activity. Two applications help us to confront this theoretical reflexion to the concrete challenges of the XXI century: The design of the Nationally Determined Contributions to mitigate climate change and the design of carbon pricing policies. I elaborate on one particular analytical approach to planning, the main objective of which is to foster collective deliberation and bargaining. The important ‘facts’ to reproduce here should include the ‘state of the debate’. The modelling activity should be able to capture the various stakeholders’ visions about the constraints and objectives of collective projects. The main role of such ‘dialogue analysis’ is to clarify the sources of disagreements about the best design of a sustainable development strategy.