یک روش ساده برای هماهنگی سیاست های پولی بین المللی

This paper analyzes the strategic interaction between the monetary policymakers of two countries, in an intertemporal general equilibrium model with nominal rigidities and imperfect competition. It offers an excursus on non-cooperative towards cooperative solutions. In a non-cooperative equilibrium the monopolistic allocation prevails in both countries, because of the incentive to use strategically the terms of trade. In a cooperative solution where both policymakers internalize the externalities given by the terms of trade, the competitive allocation is reached. However, cooperation can be counterproductive. We then characterize a problem of delegation in which the set of choice is restricted to the Pareto efficient allocations and in which the participation constraints implied by the non-cooperative equilibrium are taken into account.

The state of the art has changed: Corsetti and Pesenti (2001) have shown how to reconcile rigor in microfoundations and ‘tractability’ through a two-country general equilibrium model with nominal rigidities and monopolistic competition. In their paper, once a closed-form solution is obtained, it is possible to analyze the effect of unanticipated monetary policy shocks, even of large size, and to compute well-defined welfare functions. We utilize their simple framework in order to address the issue of international monetary policy coordination. We study the normative implication of different forms of strategic interaction, thus revisiting the basic findings of the ad hoc literature on international monetary policy coordination, with no ‘lack of explicit microeconomic underpinnings’.2 Given that wages are predetermined, monetary policy has an influence on real activity and welfare. In this model, there are two distortions: one is ‘structural’ and is given by the monopolistic-competition factor market, the other is ‘strategic’ and is given by the terms of trade. In a closed-economy model, monetary policy would get rid of all the distortions induced by monopolistic competition. Real wages would be equated to the marginal cost of labour in terms of utility — the competitive allocation. In an open-economy model, when the policymakers act in a non-cooperative way, the ‘strategic’ distortion given by the terms of trade is in conflict with the objective of eliminating the monopolistic distortion. Were both policymakers to push their economies at the competitive level, each policymaker would have an incentive to contract its money supply. In fact the reduction in utility that comes from the decrease in consumption is more than offset by the reduction in the disutility of producing goods, since the ‘burden’ of production is shifted to the other country through an improvement of the terms of trade. The strategic use of the terms of trade is at the root of the ‘contractionary bias’. This contraction is larger, the higher are the degrees of openness of the economy and the higher is the degree of substitutability in utility between the home and foreign goods. Instead, in the traditional literature (e.g. Canzoneri and Henderson, 1991), the ‘contractionary bias’ emerges because the improvement of terms of trade can lower inflation. We investigate if other forms of interaction can improve upon the non-cooperative equilibrium. Firstly, we consider the outcome of a cooperative agreement, in a decentralized setting, where both policymakers consider as given the exchange rate and thus, in a world of preset prices and wages, the terms of trade. By internalizing the distortions induced by the terms of trade, policymakers can also eliminate the distortion given by monopolistic competition. As in Rogoff (1985), cooperation reduces the incentive to contract money supply and, moreover, can be counterproductive. In fact, the welfare of the non-cooperative solution can be Pareto improved only if the difference in the ‘economic size’ of the countries is not large. We then investigate a form of centralized cooperation in which society delegates the conduction of monetary policy to a central institution. As the degree of substitutability in utility between the goods increases, there is more room for cooperation. In fact, the incentive to a ‘strategic’ use of the terms of trade is stronger and the ‘contractionary bias’ is larger. It follows that the competitive allocation can be implemented also for a large difference in ‘economic size’ across countries. In this case, there is a rationale for delegating the conduction of monetary policy to a central institution that completely internalizes the distortions induced by the terms of trade and achieves the competitive allocation. The work is organized as follows. In the next two sections, the Corsetti and Pesenti model is briefly outlined. Section 4 discusses the non-cooperative Nash equilibrium and its sub-optimality properties. Section 5 discusses the cooperative solution in a decentralized setting. Section 6 presents the characteristic of the Pareto frontier, while Section 7 studies the problem of optimal delegation.

In this paper we have shown how a model of imperfect competition with nominal rigidities can be useful and powerful in addressing normative analyses. We have focused on monetary shocks with the aim of reviving the literature on international policy coordination in a micro-founded model. We have found several similarities: the ‘contractionary bias’ and the inefficient outcome of the Nash equilibrium; the possibility that cooperation can be counterproductive; the rationale for delegating monetary policy to a central institution. We have offered different explanations: all the conclusions can be read in terms of the interaction between the monopolistic distortions and the terms of trade externalities, with a specific attention given to the different ‘economic’ sizes of the countries and to the degree of substitutability of the goods. As the degree of substitutability increases, the incentive to a strategic use of the terms of trade increases and the optimal delegation implies a common institution that leads the economies to the competitive allocation. There are two directions toward which further studies of international monetary policy coordination should be addressed. Firstly, in the model presented here, monetary policy is ‘passive’. Other sources of fluctuations, such as productivity or demand shocks, should be added in order to study the optimal stabilization policy under different monetary regimes. Secondly, the model presented here is ‘static’. A stochastic dynamic general equilibrium model can be more powerful in addressing the strategic interaction between monetary policymakers. Along these lines, a better characterization of the behavior of the monetary policymaker in its response to the shocks affecting the economy can be analyzed.