Debates in Macroeconomics: Monetarism, New Classical Theory, and Supply Side Economics

第 2 9 章 總體經濟學的爭論 : 貨幣學派， 新古典理論及 供給面經濟學派

經濟學的演變 古典學派：亞當斯密 1776 “國富論” 政治經濟學 (經濟學鼻祖) ；自由放任(自由經濟) 古典學派：亞當斯密 1776 “國富論” 政治經濟學 (經濟學鼻祖) ；自由放任(自由經濟) 個體經濟學：馬歇爾 “經濟學原理” 經濟大恐慌：1930－1940 長期失業 凱因斯學派：1936 “就業、利息與貨幣的一般理論” ；總體經濟學；政府干涉經濟。 停滯性通貨膨脹：1970 年代 貨幣學派、新興古典學派、供給面經濟學派

Keynesian Economics In a broad sense, Keynesian economics is the foundation of modern macroeconomics. In a narrower sense, Keynesian refers to economists who advocate active government intervention in the economy. Two major schools decidedly against government intervention have developed: monetarism and new classical economics.

凱因斯學派的經濟學 廣義的來說，凱因斯學派的經濟學是現代總體經濟學的基礎。狹義而言，凱因斯學派的經濟學家們倡導，政府積極干涉經濟體系。 其後所發展出的兩個主要經濟學派：貨幣學派與新興古典學派，他們則是反對政府干涉經濟。

Monetarism The main message of monetarism is that money matters. The monetarist analysis of the economy places emphasis on the velocity of money, or the number of times a dollar bill changes hands, on average, during a year; the ratio of nominal GDP to the stock of money (M): GDP is an imperfect measure of transactions to use in calculating velocity because it does not include transactions in intermediate goods or in existing assets, some of which are made using money and do influence the number of times money changes hands during a year. or

貨 幣 學 派 貨幣學派主要強調在貨幣供給量。 他們在經濟的分析上，著重在 「貨幣的流通速度」，也就是說，在一年內一元貨幣在人们手中流轉的次數，亦即是名目GDP對貨幣存量(貨幣供給量)(M)的比例： or

The Quantity Theory of Money The quantity theory of money is a theory based on the identity , which assumes that the velocity of money (V) is constant. Then, the theory can be written as the following equality: If there is equilibrium in the money market, then the quantity of money supplied is equal to the quantity of money demanded. When M is taken to be the quantity of money demanded, this equality would make the quantity of money demanded dependent on nominal GDP, but not the interest rate. This is contrary to the theory developed in chapter 22, which had the demand for money depending on both income and the interest rate.

貨 幣 數 量 學 說 貨幣數量學說是以方程式 M × V ＝ P × Y 貨 幣 數 量 學 說 貨幣數量學說是以方程式 M × V ＝ P × Y 為其理論基礎，其中假設貨幣的流通速度(V)為固定。於是此理論的方程式可寫為 M × V ＝ P × Y 若貨幣市場為均衡狀態，則貨幣供給量等於貨幣需要量。當 M 代表貨幣需求量時，此一等式說明了貨幣需求量的多寡決定名目GDP ( P × Y ) ，而 不是 利率。

利率的決定 古典學派：可貸基金理論 利率 利率決定於可貸基金需要 與可貸基金供給。 可貸基金數量 凱因斯：”流動性偏好理論“：利率決定於 古典學派：可貸基金理論 利率 利率決定於可貸基金需要 與可貸基金供給。 可貸基金數量 凱因斯：”流動性偏好理論“：利率決定於 幣需要與貨幣供給。

The Quantity Theory of Money Recent data on the U.S. economy shows that the demand for money does not appear to depend only on nominal income, but also on the interest rate. Also, the velocity of money is far from constant. There is a rising long-term trend in velocity, but fluctuations around this trend have been quite large. However, whether velocity is constant or not may depend partly on how we measure the money supply. When people switch assets from M1 to M2, M1 decreases, thus the ratio of GDP to M1 must have gone up. This is not true for M2 because M2 includes M1. With no change in GDP and no change in M2, the velocity of money would not change.

貨 幣 數 量 學 說 最近美國的經濟數據顯示，貨幣需求不旦決定名目所得外還決定利率。 貨 幣 數 量 學 說 最近美國的經濟數據顯示，貨幣需求不旦決定名目所得外還決定利率。 同時，貨幣的流通速度並非是固定。長期來看，流通速度是呈現上漲型，且在上漲趨勢中大幅波動。 無論如何，不管流通速度是否固定，主要還是在於我們如何去算出貨幣供給量。

The Velocity of Money, 1960 I – 2000 II

1960至2000 的貨幣流通速度 從圖形中我們可看出，美國從1960年到2000年，貨幣流通速度是呈現上升的趨勢。

Inflation is Purely a Monetary Phenomenon Inflation (an increase in P) is always a purely monetary phenomenon. If the money supply does not change, the price level will not change. The view that changes in the money supply affect only the price level, without a change in the level of output, is called the “strict monetarist” view. This view is not compatible with a nonvertical AS curve in the AS/AD model. However, almost all economists agree that sustained inflation is purely a monetary phenomenon. Inflation cannot continue indefinitely without increases in the money supply.

通貨膨脹純粹是一種貨幣現象 通貨膨脹(P的增加)純粹是一種貨幣現象。若貨幣供給量沒有改變，則物價水準也不會改變。這種貨幣供給量的改變僅會影響物價水準而不會影響到產出量水準的觀念，稱之為“嚴謹的貨幣學派”觀念。 這種觀念在AS/AD模型中並不能與非垂直型的AS曲線相提並論。無論如何，幾乎大部份的經濟學家們都同意，持續性的通貨膨漲純粹是一種貨幣的現象。

Inflation is Purely a Monetary Phenomenon The “strict monetarist” view is not compatible with a nonvertical AS curve because, if the AS curve is nonvertical, an increase in M, which shifts the AD curve to the right, increases both P and Y.

通貨膨脹純粹是一種貨幣現象 依”嚴謹的貨幣學派”觀點，它不能與非垂直型的AS曲線相提並論。因為，若AS曲線為非直線型，則M的增加，會引起AD曲線的右移，此會讓P與Y同時提高。

The Keynesian/Monetarist Debate Milton Friedman has been the leading spokesman for monetarism over the last few decades. Most monetarists argue that inflation in the United States could have been avoided if only the Fed had not expanded the money supply so rapidly.

凱因斯學派/貨幣學派 的爭論 Milton Friedman弗利得曼，充當貨幣學派的領導發言人已數十年。 凱因斯學派/貨幣學派 的爭論 Milton Friedman弗利得曼，充當貨幣學派的領導發言人已數十年。 大部份的貨幣學派學者認為，若美國的聯邦準備理事會不要快速的擴張貨幣供給量，則通貨膨漲就可避免在美國發生。

The Keynesian/Monetarist Debate Most monetarists do not advocate an activist monetary policy stabilization—expanding the money supply during bad times and slowing its growth during good times. Time lags are the most common argument against such management. Monetarists advocate a policy of steady and slow money growth, at a rate equal to the average growth of real output (Y).

凱因斯學派/貨幣學派 的爭論 大部份的貨幣學派學者並不主張積極的貨幣穩定政策—在經濟不景氣的時後擴張貨幣供給量，而經濟繁榮的時候降低貨幣供給增加率。 時間上的落差是對這種管理的方式最普遍的爭議。 貨幣學派學者主張一穩定且緩慢的貨幣成長政策，即以相等於真實產出量平均成長率的比率增加。

貨幣的應用 凱因斯學派：中央銀行的貨幣政策可調整一國的經濟情勢。經濟不景氣時，可採擴張性貨幣政策；通貨膨脹時，可採緊縮性貨幣政策。 貨幣學派：”貨幣供給法則” 。中央銀行只要將貨幣供給量的增加率控制在一穩定的增加率上，則一國的經濟就可穩定成長，同時經濟也不會有太大的波動。

The Keynesian/Monetarist Debate Many Keynesians advocate the application of coordinated monetary and fiscal policy tools to reduce instability in the economy—to fight inflation and unemployment. Others reject the strict monetarist position in favor of the view that both monetary and fiscal policies make a difference and at the same time believe the best possible policy is basically noninterventionist. Based on experience, the notion that monetary and fiscal policy expansions and contractions can “fine-tune” the economy is gone forever. While this controversy is still alive, the focus of current thinking in macroeconomics has been on the new classical macroeconomics.

凱因斯學派/貨幣學派 的爭論 許多凱因斯學派學者主張：應該應用貨幣政策與財政政策等工具的配合來降低經濟的不穩定—即對抗通貨膨脹與失業。 凱因斯學派/貨幣學派 的爭論 許多凱因斯學派學者主張：應該應用貨幣政策與財政政策等工具的配合來降低經濟的不穩定—即對抗通貨膨脹與失業。 其他的則是反對嚴謹貨幣學派的觀點：貨幣政策與財政政策的應用會導致經濟波動，最好的政策是政府不干涉政策。

New Classical Macroeconomics On the theoretical level, new classical macroeconomists argue that traditional models have assumed that expectations are formed in naive ways. Naive expectations are inconsistent with the assumptions of microeconomics. If people are out to maximize utility and profits, they should form their expectations in a smarter way. Naive expectations, for example, assume that people form their expectations of future inflation by assuming present inflation will continue. Instead of naively assuming the future will be like the past, they should actively seek to forecast the future.

新興古典學派的總體經濟觀 理論上新興古典學派的經濟學家認為：傳統模型乃假設預期是以自然的方式形成。 純真的預期與個體經濟學的假設並不一致。如果人們不理會效用與利潤的最大化，則他們會以機伶的方式去形成他們的預期。

New Classical Macroeconomics On the empirical level, new classical theories were an attempt to explain the apparent breakdown in the 1970s of the simple inflation-unemployment trade-off predicted by the Phillips Curve.

新興古典學派的總體經濟觀 實證上，新興古典理論嘗試去解釋1970年代違背了菲力普曲線的通貨膨脹與失業間之互換關係。

Rational Expectations The rational-expectations hypothesis assumes people know the “true model” of the economy and that they use this model to form their expectations of the future. By “true” model we mean a model that is on average correct, even though predictions are not exactly right all the time. If there were no random, unpredictable events in the economy, and if people knw the true model generating inflation, their forecasts of future inflation rates would be perfect.

理性預期 理性預期學說 假設人們知道經濟的”真實模型” ，而且他們應用這個模型去對未來做預期。 所謂 “真實” 模型，他表示一個模型 平均 而言是正確的，但也許其預測未必見得每次都是正確的。

Rational Expectations People are said to have rational expectations if they use “all available information” in forming their expectations. Because there are costs associated with making a wrong forecast, it is not rational to overlook information, as long as the costs of acquiring that information do not outweigh the benefits of improving its accuracy. If there were no random, unpredictable events in the economy, and if people knw the true model generating inflation, their forecasts of future inflation rates would be perfect.

理性預期 所謂理性預期是：他們應用 “所有可使用的訊息”來做為他們的預測。 由於錯誤的預測是要花代價，所以對訊息獲取所花的代價若超過其利益時，這種行為就是不理性。

Rational Expectations and Market Clearing If firms have rational expectations, on average, prices and wages will be set at levels that ensure equilibrium in the goods and labor markets. In other words, on average, there will be no unemployment. When expectations are rational, disequilibrium exists only temporarily as a result of random, unpredictable shocks. On average, all markets clear and there is full employment. There is no need for government stabilization.

理性預期與市場结清 如果廠商能理性預期，一般而言，其價格與工資，將會設定在保證能在財貨市場與勞動市場均衡狀態下之水準。換言之，即沒有失業的現象存在。 當預期是理性的，在無法預期的衝擊下，還是會有不均衡的現象短暫的存在。 一般而言，在所有市場结清與充分就業下，政府的穩定政策是不需要。

The Lucas Supply Function The Lucas supply function is the supply function that embodies the idea that output (Y) depends on the difference between the actual price level (P) and the expected price level (Pe): The difference between the actual price level and the expected price level is the price surprise.

盧卡斯的供給函數 盧卡斯的供給函數是：一個供給函數，他包含決定於真實物價水準(P)與預期物價水準(Pe)間差異的產出量(Y) 。 Y = f (P - Pe) 真實物價水準(P)與預期物價水準(Pe)間的差異稱之 price surprise。

The Lucas Supply Function The rationale for the Lucas supply function is that unexpected increases in the price level can fool workers and firms into thinking that relative prices have changed, causing them to alter the amount of labor or goods they choose to supply. Rational-expectations theory, combined with the Lucas supply function, proposes a very small role for government policy in the economy.

盧卡斯的供給函數 理性的盧卡斯供給函數是：物價水準未預期的上升，會愚弄工人與廠商認為相對的價格已經改變，導致他們去改變牠們想供給的勞動或財貨數量。 理性預期理論，它包含了盧卡斯供給函數，認為在經濟體系中，政府扮演一個不重要的角色。

Evaluating Rational-Expectations Theory If expectations are not rational, there are likely to be unexploited profit opportunities—most economists believe such opportunities are rare and short-lived. The argument against rational expectations is that it required households and firms to know too much. People must know the true model, or at least a good approximation of it, and this is a lot to expect.

評估理性預期理論 若預期是不理性的，這有如沒能獲得利潤的機會----許多經濟學家認為這種狀況是少有的。 反對理性預期的評論是：家庭與廠商需要具備很多的知識。人們必須知道這個真實的模型或者是最少要很接近它。

Real Business Cycle Theory The real business cycle theory is an attempt to explain business cycle fluctuations under assumptions of complete price and wage flexibility and rational expectations. It emphasizes shocks to technology and other shocks. If the AS curve is vertical, shifts in AD cannot account for real output fluctuations.

真實經濟循環理論 在價格與工資具完全伸縮性與理性預期的假設下，真實經濟循環理論，嘗試去解釋經濟循環波動的原因。它強調在技術衝擊與其他衝擊是形成經濟波動的原因。 若AS曲線是垂直狀，則AD的移動無法造成真實產出量的波動。

Supply-Side Economics Orthodox macro theory consists of demand-oriented theories that failed to explain the stagflation of the 1970s. Supply-side economists believe that the real problem was that high rates of taxation and heavy regulation had reduced the incentive to work, to save, and to invest. What was needed was not a demand stimulus but better incentives to stimulate supply.

供給面經濟學 正統的總體理論(包括需求導向的理論) ，無法解釋1970年代停滯性通貨膨脹的現象。 供給面經濟學派的學者們認為：真正的問題在於高的稅率與嚴格的規定，此減少了工作、儲蓄及投資的誘因。所以說，真正所需要的不是在於刺激需求，而較好的誘因卻是刺激供給。

The Laffer Curve The Laffer Curve shows the amount of revenue the government collects is a function of the tax rate. When tax rates are very high, an increase in the tax rate could cause tax revenues to fall. Similarly, under the same circumstances, a cut in the tax rate could generate enough additional economic activity to cause revenues to rise.

拉佛爾曲線 拉佛爾曲線表示，政府的稅收收入是租稅稅率的函數。 稅率 當稅率高時，提高 稅率會引起稅收收 入減少。反之，將 低稅率會引起稅收 拉佛爾曲線表示，政府的稅收收入是租稅稅率的函數。 稅率 當稅率高時，提高 稅率會引起稅收收 入減少。反之，將 低稅率會引起稅收 收入增加。 稅收收入

Evaluating Supply-Side Economics Among the criticisms of supply-side economics is that it is unlikely a tax cut would substantially increase the supply of labor. When households receive a higher after-tax wage, they might have an incentive to work more, but they may also choose to work less.

評估供給面經濟學 對供給面經濟學派的批評是，減稅好像不能真正的增加勞動供給。 當家庭得到較高的稅後工資，他們必定會有增加工作時間的誘因，。但是他們也許會選擇減少工作時間。

Testing Alternative Macro Models Models differ in ways that are hard to standardize. If people have rational expectations, they are using the true model, but there is no way to know what model is in fact the true one. There is only a small amount of data available to test macroeconomic hypotheses—only seven business cycles since 1950.

檢定不同的總體模型 模型會因為方法的不同而不同，而且很難標準化。 若人們能理性預期，他們會應用真實模型，但是他們無法知道那一個模型才是正確的。 自1950 年以來，僅有七個經濟循環。因此，只有少量的資料可以用來檢定總體經濟理論。