【作者】 杨光；

【导师】 张世晴； 龚刚；

【作者基本信息】 南开大学 ， 西方经济学， 2010， 博士

【摘要】 哈罗德模型对于宏观经济学的发展起到了关键作用,哈罗德模型中的两个基本问题,“非平衡经济增长”问题与“刃峰均衡”问题,更是引发了经济学家的思考,至今仍在讨论。现代宏观经济学许多发轫之作都是建立在破解哈罗德模型的两个难题、解释哈罗德模型中一些经济现象的基础上,其中最著名的工作是索洛模型。其原因是,哈罗德模型中的两个难题描述了宏观经济系统中一些无法回避的基本特征,例如,“非平衡经济增长”问题揭示了产品市场或者资本市场的稳定状态与劳动力市场的稳定状态之间的不一致性,“刃峰均衡”问题揭示了宏观经济系统的不稳定性。虽然经济学家已经尝试了各种工作对于哈罗德模型中的两个基本问题进行破解,但是他们或者改变了哈罗德模型的基本假设与结构,或者不能完全破解哈罗德模型的两个问题,使得破解工作留下了不足。本文的主要工作是在坚持凯恩斯-哈罗德假设的前提下,即坚持价格进行粘性调整,产量由需求一方来决定的假设,针对哈罗德模型两个难题进行现代表述以及破解工作,并且建立一个能够反映中国现实经济的完整的哈罗德模型。在破解“非平衡经济增长”问题方面,本文细致的刻画了劳动力市场上的动态变化,引入了就业率与投资率之间的关系,发现它们是可以同时达到稳定状态的,这样就消除了它们之间的不一致性,此时,经济达到了“平衡增长路径”。另外,本文引入了价格和工资的动态方程,并把它们作为稳定机制引入宏观经济系统之中,增强了宏观经济系统的稳定性,破解了“刃峰均衡”问题。值得注意的是,本文所使用的行为方程都是有微观基础的。通过考察现实经济现象可以发现,发展中国家相比发达国家来说,更加符合哈罗德模型所描述的经济特征。发展中国家的基本经济特征可以被总结为二元机经济。在二元经济中,现代的生产部门与落后的生产部门是并存的。在劳动力由落后部门向先进部门转移的过程中,对先进部门形成了无限制的劳动供给。发展中国家进入赶超过程,开始经济起飞的初始条件都是与这个基本特征紧密相关的。在二元经济存在的时间内,市场必定是不出清的。在市场非出清的条件下,价格是粘性调整的,而不是灵活调整。因此,以市场出清为基础的经济学理论显然忽略了发展中国家经济的这些特点。但是这却是凯恩斯-哈罗德模型的基本假设,所以这正是哈罗德模型更加能够反映发展中国家的经济现实的原因。本文针对发展中国家的经济特征,尤其是中国的经济特征,建立一个的哈罗德模型,用以解释其经济发展规律,预测其经济发展趋势。具体来说,本文主要分析内需结构的演变规律,其中还包括从功能性收入分配的角度来考察工资性收入占国民收入比例的演变规律。可以想象,由于经济体内存在无限的劳动力供给,那么工资率将会维持在较低水平,此时经济发展的主要成果由利润所得,其表现形式就是工资性收入占国民收入的比例不断下降,由于工资性收入是支撑消费的主要力量,这也必将导致消费占GDP的比重不断下降,而投资占GDP的比例不断上升。从现实经济来看,就是中国当代经济正在面临的收入分配恶化,消费不足,投资过剩等经济特点。随着经济的发展,剩余劳动力消失,工资率对劳动力市场上的供求关系恢复敏感性,工资性收入占国民收入的比例就会上升,收入分配差距就会减少,消费占GDP的比例就会随之上升,投资占GDP的比例也会逐步下降。通过模型的模拟分析,证实如上结论,即一个哈罗德模型不但解释了需求的结构性变化,也从功能性收入分配的角度解释了Kuznets曲线。总结来说,就是随着经济的发展,工资性收入占国民收入的比例以及消费占GDP的比例会出现先下降后上升的现象,呈现正U型,投资占GDP的比例会出现先上升后下降的现象,呈现倒U型。更多还原

【Abstract】 Harrod model plays a key role in the developing process of macroeconomics. Up to now, economists ponder over and discuss two basic puzzles in Harrod Model, namely Unbalanced Economic Growth puzzle and Knife Edge problem. Plenty of original benchmark models in modern macroeconomics are built to solve these two puzzles in Harrod model or to describe some phenomena in Harrod model, in which the most famous work is Solow Model. The reason is that some unavoidable basic features are presented in Harrod model. For an example, Unbalanced Economic Growth puzzle discloses the inconsistency between the steady state in commodity market or capital market and labor market while Knife Edge problem discloses the instability in macroeconomic system. Although economists have tried many kinds of methods to solve the basic puzzles in Harrod model, they either changed the foundamental assumption or structures of Harrod model or cannot solve these two basic puzzles completely, which leave much room for further exploration.The main work of this paper is to reexpress and sovle these two basic puzzles in Harrod model, and then build a complete Harrod model to reflect China economy under Keynesian-Harrodian assumptions which are price is sticky and output is decided by demand side. For solving Unbalanced Economic Growth puzzle, dynamics in labor market are descriped detailedly in this paper. After the relationship between employment rate and investment rate are introduced to our model, we can find that they can reach the steady state at the same time. Therefore, the inconsistency between employment rate and investment rate is eliminated. As a result, the economy is in a balanced growth path. Additionally, as the stability mechanism, price function and wage function are introduced into our model in this paper to enhance the stability of macroeconomic system. Therefore, Knife Edge problem can be solved. It is worthy to note that all behaviour functions used by our paper have microfoundations.In view of economic reality, we can find that developing countries are more suitable to Harrod model, compared with developed countries. The main economic feature of developing countries is concluded as dual economy in which the modern department and backward department coexist. During the process of labor transision from backward department to modern department, labor supply is unlimited for modern department. The initial conditions for the fact that the economy in developing countries is catching up with and even surpassing that in developed countries have some relationship with this main feature. When dual economy exists, markets are not clearing. If markets are not clearing, price will be sticky, rather than fully elastic. Therefore, it is easy to know that those economic theories based on clearing markets neglect the main feature of developing countries. However, this is Keynesian-Harrodian assumption, which is the reason why developing countries are more suitable to Harrod model than developed countries.In the view of economic features of developing countries, especially those in China, a Harrod model is built in this paper to explain the law of economic development and forecast the trend of economic development. Specificly speaking, the law of structures of domestic demand evolution is analyzed in this paper, in eluding the law of wage share in national income evolution from the view of functional income distribution. It can be imagined that wage rate stay in the low level because of the umlimited labor supply in economy. At this time, the achievement of economic development is transformed to profit. The manifestation is that wage share declines. Because wage income is the main power for consumption, consumption share in GDP will decline, too. Meanwhile, investment share in GDP will rise. In view of economic reality, these phenomena are the problems faced by China, such as the worsening income distribution, consumption insufficiency and surplus investment. As the economy develops, surplus labor supply will disappear, and wage rate will be sensitive to change in demand or supply in labor market. As a result, wage share will rise, income distribution will be improved, consumption share in GDP will also rise and investment share in GDP will decline step by step. All the above conclusions can be proved by our model in this paper. That is to say, Harrod model not only explain the structure development of demand but also reexplain Kuznets Curve from the perspective of functional income distribution. All in all, as the economy develops, wage share in national income and consumption share in GDP will decline and then rise, which is a U shape, while investment share in GDP will rise and then decline, which is a inverted U shape.更多还原