Discount rates for public investment in closed and open economies
Discount rates for public investment in closed and open economies
复制标题
封闭和开放经济体公共投资的贴现率
DOI：
10.2307/2551880
复制
发表时间：
1971
期刊：
影响因子：
--
通讯作者：
J. Drèze
中科院分区：
文献类型：
--
作者：
A. Sandmo;J. Drèze
让我们想象一个完全竞争的经济，在通常的新古典主义关于收益递减、偏好凸性等假设下运行。为了使我们的讨论简单，我们进一步将自己限制在一个“一好两期”框架内，在这个框架内，最初的资源可以分配给直接消费或投资，而投资生产可供未来消费的商品。在一个完美的贷款市场中，消费者将把他们的边际时间偏好利率等同于利率，而私人企业将把投资进行到私人资本的边际生产率等于利率的地步。现在假设，由于我们认为是已知的原因，经济总投资的一部分发生在公有制的“公司”中。因此，很明显，通过将公共投资的边际生产率等同于市场利率，可以找到最优的公共投资量；效率或帕累托最优的边际条件就会得到满足。现在假设经济中存在扭曲，例如以税收形式存在的扭曲，阻碍了私人部门替代和转型的边际税率的均衡。那么，确定在公共部门使用的正确折扣率就不再那么容易了。在最近的一篇论文中，Baumol bbbb2认为，在某些假设下，企业所得税在消费者的边际时间偏好率和私营企业的边际转型率之间制造了一个楔子。鲍莫尔得出结论，在这种情况下，“政府项目的贴现率选择仍然存在不可避免的不确定性”，因为这个贴现率不可能同时等于消费者的边际时间偏好率和私人资本的边际生产率。Baumol进一步指出，他找不到任何理论依据来接受这两种比率（或任何第三种选择）作为公共部门使用的适当贴现率，而且，这种比率的任何选择在某种程度上都是武断的。我们在本文中的目标是确定在效率基础上最优的公共投资贴现率，我们感谢乔治·巴塞维和亨利·图肯斯阅读了本文的手稿并提出了有用的建议。我们还要感谢莫里斯·马尔
Let us imagine a perfectly competitive economy operating under the usual neo-classical assumptions of decreasing returns, convexity of preferences, etc. To make our discussion simple we further limit ourselves to a one-good two-period framework, in which initial resources can be allocated to immediate consumption or to investment, and in which investment produces the goods available for future consumption. With a perfect loan market consumers will equate their marginal rates of time preference to the rate of interest, while private firms will carry investment to the point where the marginal productivity of private capital is equal to the interest rate. Suppose now thatfor reasons that we shall take as given-part of the total investment of the economy takes place in publicly-owned "firms". It is then obvious that the optimal amount of public investment is found by equating the marginal productivity of public investment to the market rate of interest; the marginal conditions for efficiency or Pareto-optimality will then be satisfied all around. Suppose now that there are distortions in the economy, e.g. in the form of taxes, which prevent the equalization of marginal rates of substitution and transformation in the private sector. Then it is not any longer so easy to identify the correct rate of discount to use in the public sector. In a recent paper, Baumol [1]2 has argued that, under certain assumptions, the corporate income tax drives a wedge between the marginal rate of time preference of consumers and the marginal rate of transformation in private firms. Baumol concludes that in such a case "there remains an inescapable indeterminacy in the choice of a discount rate on government projects", since this discount rate cannot simultaneously be equal to the marginal rate of time preference of consumers and the marginal productivity of private capital. Baumol further remarks that he can find no theoretical grounds for accepting either of these rates (or presumably any third alternative) as the appropriate discount rate to use in the public sector, and,that any choice of such a rate will to some extent be arbitrary. Our objective in this paper is to determine the rate of discount for public investment which is optimal on efficiency grounds, given that 1 We are indebted to Giorgio Basevi and Henry Tulkens for reading the manuscript of this paper and making useful suggestions. We also thank Maurice Mar