构建扩大内需的长效机制:收入不平等及其宏观经济效应

Building a Long-term Mechanism for Expanding Domestic Demand:Income Inequality and Its Macroeconomic Effects

本文构建了一个非瓦尔拉斯均衡的宏观经济模型,研究家庭异质性和收入不平等影响我国国内供需失衡的理论机制。根据本文研究,收入不平等造成家庭边际消费倾向的异质性,导致了总需求的不足,经济只能通过净出口达到潜在产出水平,一旦外需不足就会出现生产能力闲置。进一步研究发现,旺盛的外需有助于劳动禀赋较高的家庭提高收入从而进一步拉大收入差距,外需不足则会抑制收入差距,这解释了我国基尼系数的顺周期特性。本文的政策含义是,市场机制无法自动消除严重收入不平等以及由此造成的国内供需失衡现象,必须探索形成抑制不平等对社会总消费负面影响的政策体系、制度框架与社会文化氛围,着力推动构建扩大内需的长效机制。

The first priority of building a new pattern of development currently is to come up with a long-term governance mechanism for expanding domestic demand.The report to the 20th National Congress of the Communist Party of China pointed out that it is necessary to make sure that the implementation of the strategy to expand domestic demand is integrated with efforts to deepen supply-side structural reform.To achieve this strategic goal,this paper studies the fundamental causes of the domestic demand deficiency issue in China.The consensus in the literature on the causes of the domestic demand deficiency issue in China is income inequality.In particular,according to the principle of diminishing marginal propensity to consume(MPC),which is at the core of the Keynesian theory of effective demand,the MPC of the rich is lower than that of the poor,which implies that income inequality can be a key factor for the domestic demand deficiency issue.A large body of literature provides robust evidence that income inequality exerts a significant impact on consumption.According to the standard growth theory,however,a higher saving rate means a higher growth rate as well as a steady-state income level.Yet,this is not entirely true in China.In fact,the declining consumption rate incurs a domestic imbalance between supply and demand in China.The growth of the Chinese economy is increasingly dependent on foreign demand over time,which implies that changes in the external economic environment become a serious threat to sustained and stable macroeconomic growth in China.Obviously,although the literature that studies consumption rates or saving rates finds that income inequality can reduce consumption,it is not able to establish a direct theoretical link between income inequality and domestic imbalance between supply and demand.In addition,income inequality in China appears to be pro-cyclical and the Gini coefficient is significantly and positively correlated with foreign demand measured by the ratio of net exports to CDP.To account for these facts,it is necessary to understand the nexus of income inequality,foreign demand,and business cycles from the macroeconomic perspective.To this end,especially to explain the domestic imbalance between supply and demand in China,this paper constructs a macroeconomic model based on non-Walrasian equilibrium,which is a theoretical contribution to the literature.Based on the above argument,this paper introduces household heterogeneity into a standard macroeconomic model,using the Pareto distribution to characterize household labor endowment and thus generate inequality of wage income across households.In the model,the heterogeneity of MPC across households is generated by introducing the subsistence requirement of necessities.In particular,rich households have a lower MPC than poor households due to the subsistence requirement of necessities.This feature in the model then implies that aggregate demand is lower than potential aggregate supply,which is the domestic imbalance between supply and demand.In this case,the excessive potential supply can be digested if foreign demand is large enough.Otherwise,the excessive potential supply cannot be digested,which means there are idle capacities.In the model,more foreign demand benefits households with larger labor endowment more,which widens income inequality.Therefore,in our model,income inequality causes the dependence of the Chinese economy on foreign demand,yet foreign demand in turn affects income inequality and business cycles.Based on this paper,we provide some useful policy implications.First,our theoretical and quantitative results imply that lowering the heterogeneity of labor endowment across households can significantly increase the consumption rate in China,which can mitigate the dependence of the Chinese economy on foreign demand.Second,if foreign demand keeps declining,the Gini coefficient will go down accordingly.Third,our results imply that the market mechanism is not able to fix the income inequality problem and the resulting domestic imbalance between supply and demand.Hence,it is necessary to introduce some redistribution policies to narrow the MPC gap across households.This is a fundamental measure of building a long-term mechanism of expanding domestic demand.Last but not least,government spending can also play a complementary role in alleviating the issue of domestic demand deficiency.