本文建構一個中間財商品市場具有不完全競爭特質的內生成長模型，檢視政府當局變動不同的政策工具下，對於經濟體系的均衡成長率及福利水準的衝擊反應。本文的研究得到的以下的結論：首先，就成長的政策效果而言，政府消費性支出比重的擴張將會抑制體系經濟成長率的表現；但所得稅率的提高則對體系的經濟成長表現造成不確定的衝擊。值得一提的是，中間財廠商獨占力的提高，將會弱化上述兩者的衝擊效果。接著，在次佳境界下，體系存在一個最適的消費性政府支出比重，且該比重是大於最佳成長表現下對應的消費性政府支出比重；同時，福利最佳下的所得稅率將大於成長最佳下的水準，迥異於著名的Barro命題。最後，在次佳境界下，不完全競爭的環境將獲得較完全競爭環境更大的消費性政府支出比重。這個結論點出「不完全競爭獨占力的存在與否」與「公共消費性支出比重高低」確實具有重要的依存關係。 In this study, we consider an endogenous growth model with imperfect competition in the intermediate-good market. With this framework, we examine how the steady-state growth rate and social welfare react following the variation under different government policy tools respectively. The research of this study gets the following conclusions. First, the expansion of the fraction of comsumption expenditures in public spending will suppress steady-state growth rate. However, the expansion of income tax rate brings the uncertain influence to the steady-state growth rate. It deserves to be mentioned that the expansion of monopoly power will weaken the impact effect of both policy tools. Second, we find out that the social-welfare maximizing fraction of comsumption expensitures is higer than the growth-maximizing one. Besides, we get a result, departs from the famous Barro hypothesis, which shows that the growth-maximizing income tax rate is not equivalent to the social-welfare maximizong one. Furthermore, under the imperfect competition environment, the optimal fraction of comsumption expenditures are higer than under the perfect competition environment. This proposition points out that the important relationship between the monopoly power and the optimal public spending composition.
