We provide a series of results for a standard model where exchange is facilitated by liquid assets. Compared to past work, minimal structure is imposed on the mechanism determining the terms of trade. Four simple axioms lead to a class of mechanisms encompassing common bargaining theories, competitive price taking and other solution concepts. Using only the axioms, we establish existence and (perhaps more surprisingly) uniqueness of stationary monetary equilibrium. We also show how to support desirable outcomes using creatively designed mechanisms.
We analyze money and credit as competing payment instruments in decentralized exchange. In natural environments, we show the economy does not need both: if credit is easy, money is irrelevant; if credit is tight, money can be essential, but then credit is irrelevant. Changes in credit conditions are neutral because real balances respond endogenously to keep total liquidity constant. This is true for exogenous or endogenous policy and debt limits, secured or unsecured lending, and a general class of pricing mechanisms.