ABSTRACT
Academic theoreticians identify the market with the sole principle of reciprocity, forgetting what makes reciprocity possible. The notion of a market mechanism is presented as a necessary consequence of the basic specifications of any market economy. The different modes of failure will, by contrast, sketch the characteristics of what kind of means of payment must exist in a market economy. The commodity money system seems to meet perfectly the requirements of a market economy since barter prices are fixed market by market – which meets decentralization criterion – and, per Shapley windows, price consistency is ensured by the uniqueness of the means of payment. Legal money is not optional but the straightforward consequence of our postulates and of the features of a market economy. The level of activity of all individuals in a market economy is constrained by the minting process only.
