Summary — After identifying the market founding rules as a social institution, this paper analyzes the two main arguments which are traditionally adopted to support the market order, i.e. effectiveness and freedom. On that purpose, the consequences arising from the incompletedness of bargaining and marketing are emphasized. It is also discussed the theory by which there are two (not only one) invisible hands virtually playing in a market economic system; the first one adressing the egotism of the majority towards the common good, the other one jeopardizing the success of the first one by means of an embedded compensation power.