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librium 10F 0K 0J 6C 10F 6C James’s Clothing Karen’s Clothing Karen’s Food James’s Food C A Begin at A: Each James buys 2C and sells 2F Each James would move from Uj1 to Uj2, which is preferred (A to C). Begin at A: Each Karen buys 2F and sells 2C. Each Karen would move from UK1 to UK2, which is preferred (A to C). 39 UK1 UK2 P Price Line P’ UJ1 UJ2 Competitive Equilibrium 10F 0K 0J 6C 10F 6C James’s Clothing Karen’s Clothing Karen’s Food James’s Food At the prices chosen: Quantity food demanded (Karen) equals quantity food supplied (James)petitive equilibrium. At the prices chosen: Quantity clothing demanded (James) equals quantity clothing supplied (Karen) petitive equilibrium. C A 40 Competitive Equilibrium 10F 0K 0J 6C 10F 6C James’s Clothing Karen’s Clothing Karen’s Food James’s Food P Price Line UJ1 UK1 A P’ UJ2 UK2 C 41 競(jìng)爭(zhēng)性市場(chǎng)的經(jīng)濟(jì)效率 ? 從 C點(diǎn)可有如下幾條結(jié)論: ? 兩無差異曲線相切于 C點(diǎn),因此競(jìng)爭(zhēng)性均衡配置 C點(diǎn)是帕累托有效的; ? 此時(shí)兩種商品的邊際替代率等于它們的相對(duì)價(jià)格: ? 無差異曲線不相切則交易繼續(xù)發(fā)生; ? 在無外部干擾的條件下競(jìng)爭(zhēng)性均衡將自發(fā)實(shí)現(xiàn); ? 福利經(jīng)濟(jì)學(xué)第一定理:在一個(gè)競(jìng)爭(zhēng)性市場(chǎng)中,一切互惠交易將實(shí)現(xiàn),最終的資源的均衡配置在經(jīng)濟(jì)上將是有效率(帕累托有效)的。 KFCFCJFC MR SPPMR S ?? /42 公平與效率 ? 效用可能性邊界: ? 顯示了兩消費(fèi)者在契約曲線上實(shí)現(xiàn)了有效配置之后各自的效用水平。 ? 效用可能性邊界上的點(diǎn)是否還是公平的?對(duì)這一論斷的判斷取決于公平的定義。 43 H *Movement from one bination to another (E to F) reduces one persons utility. *All points on the frontier are efficient. Utility Possibilities Frontier James’s Utility OJ OK E F G Karen’s Utility L *Any point inside the frontier (H) is inefficient. *Combinations beyond the frontier (L) are not obtainable. Lets pare H to E and F. 44 社會(huì)福利函數(shù) ? 考慮到公平因素,在描述個(gè)體效用時(shí)還應(yīng)引入社會(huì)福利函數(shù)。 ? 平均主義:所有社會(huì)成員得到同等數(shù)量的商品; ? 羅爾斯主義:使境況最糟的人效用最大化; ? 功利主義:使社會(huì)所有成員的總效用最大化; ? 市場(chǎng)導(dǎo)向:市場(chǎng)結(jié)果就是最公平的。 ? 如何界定公平,取決于使用了上述的哪一種公平定義。競(jìng)爭(zhēng)性均衡導(dǎo)致的帕累托有效結(jié)果可能是公平的,也可能不公平。 45 福利經(jīng)濟(jì)學(xué)第二定理 ? 公平的配置是否也要求帕累托有效呢? ? 福利經(jīng)濟(jì)學(xué)第二定理: ? 如果個(gè)人的偏好是凸的,則每種有效配置(契約曲線上的每一點(diǎn))對(duì)于某些商品的初始配置而言都是競(jìng)爭(zhēng)性均衡。 ? 任何一種被認(rèn)為是公平的均衡都可以通過資源在個(gè)人之間的適當(dāng)配置來實(shí)現(xiàn),而這樣一種配置本身并不必然產(chǎn)生低效率。換言之,公平與效率并非絕對(duì)矛盾。 ? 然而,社會(huì)中所有再分配收入的計(jì)劃都是有成本的;因此,在實(shí)踐上,公平和效率目標(biāo)之間存在非此即彼的權(quán)衡關(guān)系。 46 生產(chǎn)的效率 ? 假設(shè): ? 固定投入品: ? 勞動(dòng)和資本; ? 兩種產(chǎn)品:衣服和食物; ? 眾多的投入要素供給者,他們通過出售其擁有的投入品獲得收入; ? 所獲得的收入用于消費(fèi)衣服和食物。 ? 顯然, ? 在這一框架下,供給和需求(消費(fèi)者的收入和開支)是緊密聯(lián)系的; ? 一種投入品價(jià)格的變化將引發(fā)收入和需求的變化,并產(chǎn)生反饋效應(yīng)。 47 60F 50F 40L 30L Labor in clothing production Efficiency in Production 50L 0C 0F 30K Capital in clothing production 20L 10L 20K 10K 10L 20L 30L 40L 50L Capital in food production 10K 20K 30K 30C 25C 10C 80F Labor in Food Production B C D A Each point measures inputs to the production A: 35L and 5KFood B: 15L and 25KClothing Each isoquant shows input binations for a given output Food: 50, 60, 80 Clothing: 10, 25, 30 Efficiency ?A is inefficient ?Shaded area is preferred to A ?B and C are efficient ?The production contract curve shows all binations that are efficient 48 競(jìng)爭(zhēng)性投入品市場(chǎng)的生產(chǎn)均衡 ? 據(jù)上圖: ? 競(jìng)爭(zhēng)性市場(chǎng)產(chǎn)生有效生產(chǎn)點(diǎn)。 ? 此時(shí)所有廠商的工資率( w) 和資本價(jià)格( r)都相等,并都實(shí)現(xiàn)了生產(chǎn)成本最小化: ? MRTS為等產(chǎn)量線的斜率; ? 競(jìng)爭(zhēng)性均衡在生產(chǎn)契約曲線上; ? 競(jìng)爭(zhēng)性均衡是有效率的。 LKKL MR TSrwMPMP ?? //49 生產(chǎn)可能性邊界 ? 生產(chǎn)可能性邊界: ? 顯示以固定數(shù)量的勞動(dòng)和資本能夠生產(chǎn)的兩種商品的所有組合,即生產(chǎn)契約曲線上的所有產(chǎn)量組合。 ? 每點(diǎn)的斜率表示在該生產(chǎn)組合時(shí)的邊際轉(zhuǎn)換率MRT。 ? 50 Production Possibilities Frontier Food (Units) Clothing (units) OF OC are extremes. Why is the production possibilities frontier downward sloping? Why is it concave? B, C, D are other possible binations. A A is inefficient. ABC triangle is also inefficient due to labor market distortions. 60 100 OF OC B C D 51 Production Possibilities Frontier Food (Units) Clothing (units) 60 100 OF OC A B C D B 1C 1F D 2C 1F MRT = MCF/MCC The marginal rate of transformation (MRT) is the slope of the frontier at each point. 52 產(chǎn)出效率 ? 產(chǎn)出效率: ? 應(yīng)以最小成本生產(chǎn); ? 并且生產(chǎn)的商品組合應(yīng)與人們購(gòu)買它們的意愿相一致。 ? 此時(shí)實(shí)現(xiàn)了有效產(chǎn)出及帕累托有效配置,MRS=MRT, 因此有: MRSMCMC MRTCF ???CFPP53 Indifference Curve Output Efficiency Food (Units) Clothing (units) 60 100 Production Possibilities Frontier MRS = MRT C How do you find the MRS = MRT bination with many consumers who have different indifference curves? 5