人類早喺遠古時期經已有人寫經濟學相關嘅著作,就連秦始皇都有執筆寫咗啲經濟方面嘅分析[1][2][3],但有系統性嘅經濟理論要去到成 16 世紀左右先開始出現:當時嘅歐洲人開始思考貿易同經濟政策方面嘅理論;好似重商主義(mercantilism)係 16 至 18 世紀嘅歐洲盛行嘅一套經濟政策理論,重商主義主張,一個國家嘅財富主要係由嘅累積主宰嘅,而領土唔夠金銀礦藏嘅國家只能夠靠同外國做買賣先可以得到金銀,因為噉,重商主義主張國家應該入口平價嘅物料嚟整貨品,並且用出口嘅方法嚟得到金銀[4];及後 18 世紀嘅法國思想家同作家諗出咗重農主義(physiocracy)嘅思想,將經濟體視為收入同產出嘅循環,相信只有農業能夠確實噉靠生產創造盈餘,所以指出農業係所有財富嘅基礎,因為噉,重農主義者反對重商主義者所提倡嗰種重視製造業同貿易嘅政策方針,亦都對稅收政策要點定先可以令財富最大化有所著墨[5][6]。當時學者對呢兩個理論嘅辯論成為咗現代經濟學嘅起始,而亞當史密夫對重商主義嘅批判形成咗早期嘅經濟理論[7][8]

1637 年一幅描繪一個法國港口嘅油畫

古典經濟學

內文:古典經濟學

喺 1776 年,亞當史密夫(Adam Smith)出版咗佢本名著《國富論》(The Wealth of Nations)。呢本書俾人譽為「造就經濟學誕生嘅起點」。喺呢本書入面,亞當史密夫指出土地、工作力、同資本係生產嘅三大因素,亦係一個國家嘅財富基礎,有別於主張「只有農業至係有生產力」嘅重農主義。而亞當史密夫同佢同期嘅學者所提倡嘅嗰柞諗法就係所謂嘅古典經濟學(classical economics)-呢套經濟學係現代經濟學嘅基礎,因為古典經濟學家提出咗好多現代經濟學仲用緊嘅概念[9][10]

亞當史密夫佢本人諗出咗好多為現代經濟奠基嘅諗頭:亞當史密夫指出,無論喺城市定係國家層面,分工都可以引致貿易同埋勞工生產力上升[11],當中佢個條定理「分工嘅程度係受到市場所限制嘅」俾人廣泛噉譽為現代生產理論嘅核心同埋經濟組織嘅根本原則[12];亞當史密夫亦都提倡,經濟研究應該假設人類主要係想利己嘅-亞當史密夫話,喺有競爭嘅環境之下,持有資源嘅人絕大多數都會嘗試以對自己最有利嘅方式嚟運用啲資源,而人類偏好利己嘅傾向查實唔係一件壞事,例如佢講嘅呢段嘢就成為咗經濟學上嘅名言[13][14]

原版英文:"He generally, indeed, neither intends to promote the public interest, nor knows how much he is promoting it. By preferring the support of domestic to that of foreign industry, he intends only his own security; and by directing that industry in such a manner as its produce may be of the greatest value, he intends only his own gain, and he is in this, as in many other cases, led by an invisible hand to promote an end which was no part of his intention. Nor is it always the worse for the society that it was no part of it. By pursuing his own interest he frequently promotes that of the society more effectually than when he really intends to promote it."

粵文翻譯:佢(指一個典型嘅人)普遍唔打算造福社會,亦都唔知佢做嘅嘢有幾能夠造福社會。佢透過撐國內工業多過撐國外嘅,目的只係確保自己嘅安全;而佢透過令工業產出價值最大化,目的只係要自己嘅利益,同好多情況一樣,佢(喺呢個情況下)俾一隻無形嘅手引導,令佢達到一個佢冇打算達到嘅結果。呢一點亦都唔係一定係一件壞事。透過追求自己嘅利益,佢好多時都會唔覺意之中更加有效噉造福社會。

亞當史密夫「人類主要係想利己嘅」呢個命題係現代經濟學研究嘅基本假設[15][16]

另一方面,英格蘭學者馬爾薩斯(Thomas Robert Malthus)又提出咗報酬遞減(diminishing return)嘅概念:佢指出隨住生產因素嘅數量增加,邊際產量(marginal productivity;指產量上升幾多)會下降,例如如果員工數量一路係噉升,但其他生產因素(好似機械嘅數量)數量不變,產量嘅提升率會係噉跌,令到請新員工愈嚟愈唔著數;馬爾薩斯運用呢個概念解釋,點解有陣時個經濟體當中會有人工持續處於低水平嘅情況-佢指出喺好多經濟體當中,都有工人數量上升,但其他生產因素冇變嘅情況,而呢個情況會搞到啲老細愈嚟愈冇誘因請工人,自然搞到老細愈嚟愈冇誘因俾高人工[17]。雖然馬爾薩斯嘅分析受到某啲經濟學家批評[18],但報酬遞減嘅概念對今日嘅經濟學嚟講都仲係相當有用[19]

比較優勢(comparative advantage)嘅概念都係喺古典經濟學時期出現嘅:喺 1817 年,英國經濟學家大衛·李嘉圖(David Ricardo)專注於分析收入點樣喺土地擁有者、工人、同埋資本家之間分佈。李嘉圖認為,喺土地量不變嘅情況下,隨住人口同資本係噉增加,租金會上漲,搞到人工同利潤停滯唔升,同馬爾薩斯一樣運用咗報酬遞減嘅概念。更加重要嘅係,李嘉圖用數學方式證明咗比較優勢嘅原則[20],跟手仲用埋呢條原則嚟解釋點解人同人以至國家同國家之間有誘因進行貿易,而唔係齋靠自己生產嗮所有需要嘅嘢[21]

古典經濟學亦都將學界嘅注意力帶到去價值理論(value theory)身上。價值理論係指分析人類個體重視啲乜同埋點解重視呢啲嘢,當中亞當史密夫就寫話「每一樣嘢嘅真正價錢... 反映咗要攞到佢有幾麻煩」(real price of every thing ... is the toil and trouble of acquiring it),所以一樣貨品服務嘅價值唔淨只反映咗要生產呢樣嘢要用嘅錢,仲反映咗生產呢樣嘢所造成嘅其他麻煩-呢點令到經濟學分析生產過程嗰時,唔淨只要考慮生產過程所涉及嘅資本。呢個諗頭喺當時相當有革命性[22]

馬克思經濟學

 
馬克思嘅畫像
內文:馬克思主義

馬克思主義(Marxism)係建基於古典經濟學理論上嘅一套經濟理論。喺 1867 年 10 月 1 號,德國猶太人政經學者馬克思(Karl Marx)出版咗佢嗰三本名著《資本論》(Das Kapital)嘅第一本。喺呢本書入面,馬克思對勞工同資本家對勞工嘅剝削做咗詳細嘅分析。佢認為一件貨品服務嘅價值係由生產佢嘅勞工所決定嘅,而一個勞工所生產嘅價值當中淨係得一部份係去咗個勞工度嘅,其他嗰啲會走咗去資本家嗰度,而呢個過程當中有機會出現對勞工嘅剶削,令到資本家攞走嗰部份唔合理咁大。馬克思嘅思想好有影響力,例如共產主義(communism)就好大程度上建基於馬克思主義之上嘅[23][24]

馬克思主義嘅其中一個重要主題係「衝突」。馬克思主義假設咗生產嘅過程會影響各種嘅社會現象,包括咗政治組織、法律、文化以至意識形態等,而生產方式係受制於科技等嘅因素嘅。馬克思佢仲主張,隨住生產方式改良,現有嘅生產方式組織往往會變得不合時宜,並且阻礙社會嘅進步,而呢個現象會引致某啲社會衝突,包括咗階級鬥爭(class struggle):例如如果科技上嘅進步令到機械生產變得更加有效率,有可能會令到啲老細有誘因炒工人魷魚,工人自然就會唔高興,搞到「資本家」同「工人」呢兩個階級之間起衝突,而衝突就會引致革命[25]。馬克思主義當中嘅階級鬥爭係一個好有影響力嘅概念,就算係今日嘅經濟學研究都仲會用呢個概念嚟對社會現象作出批判[26]

新古典經濟學

內文:新古典經濟學

廿世紀初係經濟學上嘅一個轉捩點-經濟學喺呢個時期由淨係研究財富,變成一個更廣泛嘅領域。早期嘅經濟學都集中於研究財富以及財富嘅生產同分配,例如頭先提過嘅亞當史密夫一味淨係講財富上嘅決策同分析,但喺廿世紀初,經濟學界發現經濟學上嘅原則同理論有好多都可以用落去教育、軍事、同醫療等嘅領域嗰度,於是經濟學家開始覺得舊有對於「經濟學」嘅定義經已唔再夠用。1932 年,英國經濟學家里奧勞·羅賓斯(Lionel Robbins)出版咗佢篇文章《An Essay on the Nature and Significance of Economic Science》(粵文:論經濟科學嘅本質同重要性)討論到呢個問題,提倡經濟學嘅定位唔應該淨係局限於「對財富嘅研究」,而係應該被視為一個研究人類行為某一部份嘅領域,佢提出稀缺性嘅概念,指出稀缺性迫使人類對點樣運用有限資源做出決擇-令到學界重新將經濟學定義為「研究人類點樣分配有限資源嘅科學領域」,並且正式將用經濟學原理分析財富以外嘅現象嘅研究納入為經濟學嘅一部份。羅賓斯嘅貢獻根本噉改革咗經濟學呢個領域[27][28][29]

新古典經濟學(neoclasical economics)呢套經濟理論係喺 1870 至 1910 年興起嘅[30]。新古典經濟學研究個體人類、家庭、同組織嘅行為同埋佢哋點樣運用手頭上嘅稀缺資源達到佢哋嘅目的。呢套經濟理論假設一個人大致上係理性嘅,喺任何時間點都喺度嘗試運用手上嘅有限資源嚟達到某啲目的,而且喺決策方面有某啲偏好。一個手上控制住某啲資源嘅個體嘗試喺資訊、時間、同自身認知能力嘅局限之下盡量擴大自己嘅利益,一個社會由多個經濟個體組成,每個個體都會按照自己嘅資源同目的嚟做決策,唔同個體嘅決策會互動,造成各種社會層面嘅經濟現象[31],例如係供應同需求噉,當一件貨品服務推出嗰陣,每個個體消費者都要按照件貨品服務嘅價格以及自己手頭上有幾多資源決定要買幾多-而成個市場裏面嘅消費者決定買嘅量就形成咗件貨品服務嘅需求。新古典經濟學理論跟手仲用呢兩個概念嚟解釋市場均衡嘅情況。另一方面,新古典理論放棄咗古典經濟學當中嘅某啲諗法,用新嘅理論分析需求方嘅價值同供應方嘅價值。呢啲做法喺當時係好有革命性,令到經濟學研究變得更加似現代所見到嘅樣[32][33]

凱恩斯經濟學

內文:凱恩斯經濟學

凱恩斯經濟學(Keynesian economics)係由英格蘭經濟學家凱恩斯(John Maynard Keynes)所創嘅一套經濟理論。喺 1936 年,凱恩斯出版咗佢本名著《The General Theory of Employment, Interest and Money》(粵文:就業、利息同貨幣通論),呢本書集中討論喺價格相對唔變嘅情況下國家收入由乜嘢因素話事,仲嘗試解釋點解喺某啲情況下,高失業率嘅問題會因為「有效需求」低得滯而唔會自行改善。凱恩斯嘅諗法對經濟分析方法有相當大嘅衝擊,而且仲令到宏觀經濟學成為獨立於微觀經濟學嘅一門經濟學子領域[34][35]。除此之外,凱恩斯經濟學仲有後續嘅學派[36]

芝加哥學派

內文:芝加哥經濟學派

芝加哥經濟學派(The Chicago School of economics)係廿世紀早期興起嘅一套經濟學理論,主張自由市場同埋貨幣主義(monetarism)。根據呢個學派嘅經濟學者(例如係佛利民;Milton Friedman),只要錢供應唔好突然擴充或者收縮,市場經濟體本質上係穩定嘅,而呢個學派嘅分析師普遍認同,錢供應上嘅問題係大蕭條嘅主要成因[37]

佛利民等嘅學者攞咗好多古典經濟學上嘅原則,並且將呢啲原則現代化。舉個簡單嘅例子說明,佛利民 1970 年嗰時喺紐約時報寫咗篇專欄,當中指出企業嘅社會責任係「運用手頭上嘅資源,喺唔呃人嘅情況同埋公開嘅競爭之下,將自己嘅利潤最大化」-用咗企業社會責任(corporate social responsibility)呢個現代嘅概念,但又好似古典經濟學噉,主張個人嘅利己行為對社會整體嘅福祉有利[38]

行為經濟學

 
賭徒謬誤(gambler's fallacy)等嘅現象說明咗,人類好多時都唔能夠對經濟效用作出正確嘅判斷[39]
內文:行為經濟學

行為經濟學(behavioral economics)係廿世紀中興起嘅一套經濟學理論,專門研究一啲非理性嘅因素-例如係心理認知情緒文化等-會點樣影響個體以至群體嘅經濟決策:直至廿世紀初都霸佔住經濟學研究嘅新古典經濟學理論假設咗,人類係大致理性(rational)嘅,對於每個決定會對自己帶嚟幾多得失曉做出大致上完美嘅運算,並且淨係一味按照運算嘅結果做決策,但打後廿世紀中嘅研究話咁快就令到學界質疑呢個諗法-佢哋發現咗,人類好多時都唔能夠對經濟價值做正確判斷,而且喺做經濟決策嗰時會受好多非理性嘅因素左右[40][41]

面對呢個問題,行為經濟學理論家提出咗有限理性(bounded rationality)嘅概念:根據有限理性,人類可以係理性嘅決策者,但佢哋喺運算能力、資訊時間、同記憶等嘅因素上受到限制,所以好多時都唔能夠做完全理性嘅決策。例如假想有個人,佢想用手頭上嘅最大噉滿足自己嘅慾望,喺完美理性嘅情況下,佢會集中淨係諗點樣用手上資源達到「最大噉滿足自己慾望」,忽略嗮第啲嘢,而且完美清楚知道每個可能選項有幾能夠滿足自己慾望;而喺有限理性嘅情況下,經濟學家就會考慮埋有啲乜嘢因素可能搞到佢做唔到完美理性嘅決策-比如話,可能嘅使錢方案多得滯,搞到個人唔可以冚唪唥考慮嗮(運算能力不足),又或者嗰個人未必知道嗮所有可能嘅選擇(資訊不足),又或者佢唔夠時間做咁大量嘅運算(時間不足)等等-喺古典經濟理論模型之上加入對「人類所面對嘅限制」嘅考量,務求創造出更加準確描述人類決策嘅理論模型[42][43]

到咗廿一世紀初為止,行為經濟學經已成為咗一個舉足輕重嘅領域,運用認知科學(cognitive science;研究心靈嘅科學理論,對人類認知能力受嘅限制等課題有相當著墨)等領域嘅知識結合傳統經濟理論,創造咗自己專屬嘅一套理論框架。而且仲有多位嚟自心理學(認知科學嘅其中一個領域)等背景嘅學者憑佢哋嘅研究奪得諾貝爾經濟學獎嘅殊榮[44][45]

睇埋

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