Institutions according to the Economics of Conventions

"Institutions", as a set of pre-existing and objective resources of justification, is the milieu where economic agents can find materials to solve their coordination problems and/or their conflicts of reproduction. "Conventions" are collective representations of Hjustified common worlds" that activate institutions and legitimise arrangements within "organisations", whose joint production of goods and rules will lead to the renewal -or the degeneracy- of prior institutional milieu. This "three terms conventionalist model" endeavors to face the difficulties encountered by the other economic approaches of institutions. It assumes an economic agent suited to coordination/reproduction failures, and unthinkable without an institutional milieu minimally consisting in Language, Money and Law. The plurality of justification orders takes account of the empirical diversity of institutions. The institutional dynamics is studied through the operations which do/undo the possibility of building "common worlds" from "plurality". "Competition", as for the space of prices, should be combined with "Critic", as for the space of values (norms). The conventionalist analysis of Capitalism puts the Marx project on the right side, inferring the exploitation theory from a theory of justice, rather than the contrary.