| Summary: | Friedman法則已經是貨幣經濟學中一個基礎且重要的議題。職是之故，本論文使用貨幣內生成長理論來分析不完全競爭市場、生產外部性、廠商的獨佔力與交易性的摩擦如何影響貨幣政策的成長與福利效果。論文的第二章，我們建立一個具有不完全競爭市場與生產外部性特質的貨幣內生成長模型，並且貨幣當局採取釘住通貨膨脹率的方式來當作貨幣政策的法則。基於這樣的設定，我們不但可以探討貨幣當局是否可以利用釘住通貨膨脹率的方式來影響均衡成長率與就業，更能分析貨幣當局如何從福利極大的觀點來設定最適的通貨膨脹率。
第三章架構一個同時具有R&D與資本累積兩種經濟成長動能的貨幣內生成長模型，並且發現擴張性的貨幣政策導致R&D與資本累積的減少，進而傷害了經濟成長與社會福利。除此之外，透過R&D的管道，較高的獨佔力將增強貨幣政策的成長與福利效果。若透過資本累積的管道，較高的獨佔力將弱化貨幣政策的成長與福利效果。據此，獨佔力是否增強或弱化通貨膨脹的福利成本乃是倚靠兩種成長引擎的相對重要性。在第三章，我們也使用美國與歐元區的資料來量化評估與比較這二個經濟體的通貨膨脹的福利成本，並且發現美國與歐元區經濟體系的R&D管道的影響力高於資本累積管道。
第四章乃利用一個以搜尋為基礎的貨幣成長模型來分析通貨膨脹的成長與福利效果。我們運用資本外部性的特質來驅動經濟的持續成長，並比較兩部門的搜尋模型與既有的交易付現(cash-in-advance)成長模型的通貨膨脹效果後，我們發現這二種模型對通貨膨脹效果有二個重要的差異性。第一，勞動內生在交易付現模型的通貨膨脹成長效果中扮了演一個重要的角色。然而，在搜尋模型之中，分權市場之消費效果才是一個影響通貨膨脹成長效果的重要管道。第二，我們使用量化分析來評估通貨膨脹的福利成本，並且發現貨幣供給長率降低至Friedman法則成立時，搜尋模型相對於交易付現模型有較高的福利利得。然而，貨幣供給成長率降低至零通貨膨脹率(zero inflation)時，交易付現模型卻有較高的福利利得。為何二種模型對通貨膨脹的福利成本呈現相對性的結果？原因來自於內生成長的特質在搜尋模型的架構下產生了福利水準與通貨膨脹率的關係呈現非線性狀態。
=== The Friedman rule has been a fundamental issue in monetary economics. This dissertation uses monetary endogenous growth theories to analyze how market imperfections, production externalities, the market power of firms, and trading frictions influence the growth and welfare effects of monetary policy. In chapter two, we develop a monetary endogenous growth model with market imperfections and production externalities. The notable feature of the model is that the monetary authority implements inflation targeting as a monetary policy rule. Based on the model, this chapter examines not only whether the anchor of the inflation rate set by the monetary authority governs the balanced growth rate and the level of employment, but also how the monetary authority sets its optimal anchor of the inflation rate from the viewpoint of welfare maximization.
In chapter three we develop a monetary endogenous-growth model in which R&D and capital accumulation are both engines of long-run economic growth. We find that monetary expansion hurts economic growth and social welfare by reducing R&D and capital accumulation. Furthermore, a larger market power of firms strengthens these growth and welfare effects of monetary policy through the R&D channel but weakens these effects through the capital-accumulation channel. Therefore, whether the market power of firms amplifies or mitigates the welfare cost of inflation depends on the relative importance of the two growth engines. Finally, we calibrate the model using data in the United States and the Euro Area to quantitatively evaluate and compare the welfare cost of inflation in these two economies and find that the R&D channel dominates in both economies.
In chapter four, we develop a search-based monetary growth model to analyze the growth and welfare effects of inflation. We introduce endogenous growth via a capital externality into a two-sector search model and compare the effects of inflation to those from a standard cash-in-advance (CIA) growth model. We find two important differences between the two approaches. First, while the growth effect of inflation operates solely through endogenous labor supply in the CIA model, the growth effect of inflation operates through an additional consumption effect in the decentralized market in the search model. Second, we quantitatively evaluate the welfare cost of inflation and find that the search model exhibits a larger (smaller) welfare gain than the CIA model when we decrease the growth rate of money supply to achieve the Friedman rule (zero inflation). These contrasting results arise because welfare is non-linear in inflation in the search model due to endogenous growth whereas it is linear in the CIA model.
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