三、宏观经济学——消费投资理论与财政政策.ppt

,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,三、消费投资理论与财政政策,THE THOERY OF CONSUMPTION AND INVESTMENT,，,AS WELL AS FISCAL POLICY,萨伊定律与古典经济理论,萨伊,定律：,Supply can create its own demand,。,这一定律有三个重要假设条件：,投资恒等于储蓄。,劳动力市场的均衡可以由工资率来调节。,货币呈“中性”状态。从投资恒等于储蓄定律出发，货币只有价值尺度和交换媒介两种职能，没有贮藏职能。即货币供应量的多少及其增减变化，不影响商品供需量和供需结构，也不影响商品的交换比率。,凯恩斯理论与古典理论的差异,古典理论认为，工资是弹性的，弹性工资会导致充分就业。凯恩斯认为，工资是刚性的。,古典理论认为，消费是利率的函数。凯恩斯认为，消费是收入的函数。,古典理论认为，利率由资本供求决定。凯恩斯认为，利率由货币供求决定。,古典理论认为，货币呈中性状。凯恩斯认为，货币供应量变化会影响价格水平和收入数量和结构变化，因此不呈中性状。,消费函数与储蓄函数,消费函数：,C =a+,bY,边际消费倾向：,储,蓄函数：,S =,a+(1,b)Y,消费理论：绝对收入假说,消费者的消费支出取决于其收入的绝对水平。,凯恩斯,(,Johm,Maynard Keynes),提出的社会消费的基本心理法则：当人们的收入增加时，其消费不会以同一绝对量增加，即随着家庭收入水平的提高，家庭平均消费倾向趋于下降。,但美国的经验数据并不支持凯恩斯的这一结论。阿瑟,斯密塞斯,(,A.Smithies),认为，有些因素影响平均消费倾向下降趋势：,1,、农村人口大量向城市转移；,2,、人口出现老龄化趋势；,3,、技术进步使过去的奢侈品变化现在的生活必需品。,消费理论：相对收入假说,美国经济学家詹,姆,斯,杜森贝里,(,James S.,Duesenberry,),有两个假设：,家庭消费决策主要参考其他同等收水平家庭的消费，即消费有模仿和攀比的习性。,家庭消费即受本期收入绝对水平的影响，更受以前消费水平的影响。当收入水平变化时，家庭宁愿改变储蓄以维持消费的稳定。,由此可见，经济中消费的变动要比收入变动稳定得多。,消费理论：持久收入假说,货币主义创始人米,尔,顿,弗里德曼,(,milton Frideman,),的理论。,将家庭收入分为持久收入和暂时收入，将消费也分为持久消费和暂时消费。持久收入包含着家庭对未来收入的预期。,持久消费占持久收入的比例基本不变。这一命题所含的思想是：家庭之间消费倾向的差异，实际上是由暂时收入决定的。,暂时消费和暂时收入之间不存在固定关系，即家庭暂时收入的边际消费倾向基本为零。,消费理论：生命周期假说,美国经济学家,F,莫迪利安尼,(,Franco,Modigliani,),提出的理论，这一理论的重点在人们的长期收入上。,人的一生分为少年时期、壮年时期和老年时期。在少年和老年时期，消费大于收入，因此必须在壮年时期进行储蓄。,从短期看，消费在收入中的比例与收入的增减呈反方向变化；从长期看，这一比例保持不变。,财产对消费的影响：在一定财产条件下，收入变动的边际消费倾向接近,1,；在一定收入水平条件下，财产变动的消费倾向接近于市场利率。,资本边际效率,Marginal Efficiency of Capital,MEC,是,一种贴现率，用这一贴现率将资产的未来收益折为现值，正好等于该资产的供给价格。这一价格是能满足厂商增加该资产的边际价格，因此也称为重置成本。,投资动机与储蓄动机,在,现实经济中，投资和储蓄往往是不等的。这是因为储蓄与投资的动机是不一样的。,企业储蓄的直接动机是为投资。当投资大于储蓄时，必须从外部筹集资金。,家庭的储蓄动机各不相同，如为购置住宅；度假；留给下一代；为高利率吸引；或有节俭习惯等，都与企业投资无关。,市场机制一般不能迅速而有效地在储蓄与投资之间进行沟通。这是造成经济周期性波动的基本原因。,简单的需求均衡模型,AD,Y=AD,a+I,C+I,E,b,0,Y*,Y,乘数原理（,1,）,Multiplier Theorem,投资乘数：,政府支出乘数：,转移支付乘数：,乘数原理是指：每增加一笔需求支出（如增加投资），由此而引起的国民产出的增加量并不仅限于这笔支出，而是原来支出的若干倍。,乘数原理（,2,）,Multiplier Theorem,税收乘数：,累进税收乘数：,进口乘数：,预算平衡乘数,How Fiscal Policy Influences Aggregate Demand,财政政策如何影响总需求,Fiscal policy refers to the governments choices regarding the overall level of government,purchases,政府购买,or,taxes,税收,.,How Fiscal Policy Influences Aggregate Demand,Fiscal policy influences saving,investment,and growth in the long run.,财政政策影响储蓄、投资和长期经济增长。,How Fiscal Policy Influences Aggregate Demand,In the short run,fiscal policy primarily affects the aggregate demand.,从短期看，财政政策主要影响总需求。,Changes in Government Purchases,政府购买变化的影响,The federal governments control of the economy is both direct and indirect.,Its expenditures have a direct effect on aggregate demand.,财政支出对总需求形成直接影响。,Taxes and tax policy have an indirect effect on consumer spending.,税收和税收政策通过消费者支出形成间接影响。,The Effects of Changes in Government Purchases,There are two macroeconomic effects from government purchases.,The multiplier effect,乘数效应,The crowding-out effect,挤出效应,The Multiplier Effect of Government Purchases,政府购买的乘数效应,Quantity,of Output,0,Price,Level,The Multiplier Effect of Government Purchases,Aggregate,demand,AD,1,Quantity,of Output,0,Price,Level,The Multiplier Effect of Government Purchases,Aggregate,demand,AD,1,Quantity,of Output,0,Price,Level,1.,An increase in government purchases of$20 billion initially increases aggregate demand by$20 billion,The Multiplier Effect of Government Purchases,Aggregate,demand,AD,1,AD,2,Quantity,of Output,0,Price,Level,1.,An increase in government purchases of$20 billion initially increases aggregate demand by$20 billion,The Multiplier Effect of Government Purchases,Aggregate,demand,AD,1,AD,2,Quantity,of Output,0,Price,Level,1.,An increase in government purchases of$20 billion initially increases aggregate demand by$20 billion,2.,but the multiplier effect can amplify the shift in aggregate demand.,The Multiplier Effect of Government Purchases,Aggregate,demand,AD,1,AD,2,Quantity,of Output,0,Price,Level,1.,An increase in government purchases of$20 billion initially increases aggregate demand by$20 billion,AD,3,2.,but the multiplier effect can amplify the shift in aggregate demand.,The Crowding-Out Effect,挤出效应,Fiscal policy may not affect the economy as strongly as predicted by the multiplier.,财政政策对经济的影响并不象乘数所显示得那么强烈。,An increase in government purchases causes the interest rate to rise.,政府购买增加导致利率上升。,A higher interest rate reduces investment spending.,高利率会降低投资支出。,The Crowding-Out Effect,This reduction in demand that results when a fiscal expansion raises the interest rate is called the,crowding-out effect.,The Crowding-Out Effect,The crowding-out effect tends to dampen the effects of fiscal policy on aggregate demand.,挤出效应会减弱财政政策对总需求的影响力。,The Crowding-Out Effect,Aggregate demand,AD,1,(b)The Shift in Aggregate Demand,1.,When an increase in government purchases increases aggregate demand,Quantity of Output,0,Price Level,AD,2,AD,3,4.,which in turn partly offsets the initial increase in aggregate demand.,(a)The Money Market,$20,billion,3.,which increases the equilibrium interest rate,Quantity of Money,Quantity fixed by the Fed,0,r,2,r,1,Money demand,MD,1,Money supply,Interest Rate,MD,2,2.,the increase in spending increases money demand,Changes in Taxes,（,税率变化）,When the government cuts taxes,it increases households take-home pay.,Households save some of this additional income.,家庭将额外收入进行储蓄,Households also spend some of it on consumer goods.,家庭将额外收入中的一部分用于购买消费品,Increased household spending shifts the aggregate-demand curve to the right.,家庭支出的增加导致总需求曲线向右移动,Changes in Taxes,The size of the shift in aggregate demand resulting from a tax change is also affected by the multiplier and crowding-out effects.,受税收变化影响的总需求移动规模同样也会受到乘数和挤出效应的影响。,Changes in Taxes,The size of the shift in the aggregate demand is also determined by the households perceptions about the permanency of the tax change.,总需求移动规模也取决于家庭对税收长期变化的预期。,Using Government Policy to Stabilize the Economy,利用政府政策稳定经济,Economists disagree about how active the government should be in attempting to stabilize the economy.,干预性财政政策,公共工程计划：大规模公共投资，通过乘数作用刺激经济复苏。,就业计划：为失业人员创造就业岗位。,转移支付计划：给低收入者以补贴，通过他们的高边际消费倾向，刺激消费品的购买。,改变税率：通过税率的调整，既可刺激经济复苏，又可抑制通货膨胀。,