Dynamic Processes of Social and Economic Interactions: On the Persistence of Inefficiencies

This Paper considers the efficiency and convergence properties of dynamic processes of social and economic interactions, such as exchange economies, multilateral negotiations, merger and divestiture transactions, or legislative bargaining. The key general feature of the economy is that agents can implement any move from one state to another as long as a pre-specified subset of agents approve. By means of examples, we show that inefficiencies may occur even in the long run. Persistent inefficiencies take the form of cycles between states or of convergence to an inefficient state. When agents are sufficiently patient, we show very generally that the initial state from which the process starts plays no role in the long-run properties of equilibria. Also, when there exists an efficient state that is externality free (in the sense that a move away from that state does not hurt the agents whose consent is not required for the move), then the system must converge to this efficient state in the long-run. Conversely, long-run efficiency can only be attained in a robust way if there exists an efficient externality-free state. It is thus more important to design transitions guaranteeing the existence of an efficient externality-free state rather than to implement a fine initialization of the process.