公地悲剧翻译稿11页word文档
第九讲 公地悲剧
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这个故事中所讲的就是公共资源的悲剧。 这一理论最早是由美国生物学家加勒特· 哈丁 于1968年在《科学》杂志上发表的文章《公地悲 剧》(The Tragedy of the Commons )中提 出来的,因此又被称为“哈丁悲剧”。
在那篇文章中,哈丁首先讲述了一个关于牧 民与草地的故事。 美国马萨诸塞州的一片公共草地向牧民完全开 放,可以用来放牧羊群。只有羊群的数目控制在一 定范围内的时候,既可以使羊吃得膘肥肉嫩,也能 使草地处于自然恢复的良性循环,保持肥沃。
瓠里子到吴国拜望相国,然后返回粤地。相国 派一位官员送他,并告诉他说:“你可以乘坐官船 回家。” 瓠里子来到江边,放眼望去,泊在岸边的船有 一千多条,不知哪条是官船。送行的官员微微一笑, 说道:“这很容易。我们沿着岸边走,只要看到那 些船篷破旧、船橹断折、船帆破烂的,就一定是官 船了。” 瓠里子照此话去找,果然不错。
之所以叫悲剧是因为每个当事人都知道资源将由于过度使用而枯竭但每个人对阻止事态的继续恶化都感到无能为力而且都抱着及时捞一把的心态加剧事态的恶化
《趣味博弈论》
杨驭云
华南师范大学南海校区
第九讲 公地悲剧
那由最大人数所共享的事物,却只得到最少 的照顾 。 ——亚里士多德
《郁离子》是明代刘基(刘伯温)的一本寓言 散文集,包括多篇具有深刻警世意义的作品,其中 有一篇讲了官舟的故事。所谓官舟量应该 是两个牧民各养一只羊,他们各自得到200元的 收益。但如果两个牧民都是“理性经济人”,他 们无一例外会选择各养2只羊,各自得到160元的 收益。
于是,所有的牧民都增加一头头的羊只。最后, 草地被过度放牧,草地退化、消失,所有的羊都饿 死了。 悲剧发生了。
之所以叫悲剧,是因为每个当事人都知道资 源将由于过度使用而枯竭,但每个人对阻止事态的 继续恶化都感到无能为力,而且都抱着“及时捞一 把”的心态加剧事态的恶化。
公地悲剧与反公地悲剧的原因及对策
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公地悲剧【Tragedy of The Commons】当资源或财产有许多拥有者,他们每一个人都有权使用资源,但没有人有权阻止他人使用,由此导致资源的过度使用,即为“公地悲剧”。
如草场过度放牧、海洋过度捕捞等。
公地作为一项资源或财产有许多拥有者,他们中的每一个都有使用权,但没有权利阻止其他人使用,从而造成资源过度使用和枯竭。
过度砍伐的森林、过度捕捞的渔业资源及污染严重的河流和空气,都是“公地悲剧”的典型例子。
之所以叫悲剧,是因为每个当事人都知道资源将由于过度使用而枯竭,但每个人对阻止事态的继续恶化都感到无能为力。
而且都抱着“及时捞一把”的心态加剧事态的恶化。
公共物品因产权难以界定而被竞争性地过度使用或侵占是必然的结果。
反公地悲剧【Tragedy of Anti-Commous】1998年,美国黑勒教授(Michael·A·Heller)在《The Tragedy of Anti-Commous》一文中提出“反公地悲剧”理论模型。
他说,尽管哈丁教授的“公地悲剧”说明了人们过度利用(overuse)公共资源的恶果,但他却忽视了资源未被充分利用(underuse)的可能性。
在公地内,存在着很多权利所有者。
为了达到某种目的,每个当事人都有权阻止其他人使用该资源或相互设置使用障碍,而没有人拥有有效的使用权,导致资源的闲置和使用不足,造成浪费,于是就发生了“反公地悲剧”。
二者的区别概述公地与反公地“悲剧”的本质在于产权问题。
产权一般具有两种形态:公共产权和私人产权。
当某种资源为某个人单独所有时,该资源为私人财产,其产权为私人产权。
它具有产权制度边界清晰、产权归属明确,所有权效率高的特点。
当某种资源为两个或两个以上当事人所有时,称为公共财产,其产权为公共产权。
它具有以下特点:在消费规模上没有限制,每个社会成员都能享受这项资源的权益,所以存在收费困难;每个当事人天然享有资源权益,无需采取交费申请加入的方式;每一当事人在使用该资源时,会影响和损害其他成员的利益,即存在外部性。
Slovenské vzory dělení slov as pro změnu
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Slovenskévzory dˇe leníslov:ˇc as pro zmˇe nu?Petr SojkaMasarykova univerzita v Brnˇe,Fakulta informatikyBotanická68a,60200BrnoEmail:sojka@fi.muni.czAbstrakt:Dˇe leníslov neboli algoritmickásegmentace velkémnožinyˇr e-tˇe zc˚u nˇe jakého jazyka je problémˇc astˇe jšínežby se na prvnípohled zdálo.Pro volnˇešiˇr itelnéslovenskédˇe leníslov zatím existuje pouzeˇr ešenívy-cházejícíz definice slabiky ve slovenštinˇe,bez rozsáhlého pokrytívýjimek.Z více nežmiliónu shromáždˇe ných a rozdˇe lených slov se podaˇr ilo vyge-nerovat programem P AT G EN novévolnˇešiˇr itelnévzory,kterése s nepra-videlnostmi jazyka vyrovnávajílépe neždosud dostupnéˇr ešení.Výsledekje použitelnýnejen v distribucích T E Xu,ale i v dalších systémech jako na-pˇríklad O PEN O .Použitéa diskutovanétechniky bootstrappingu,stratifikace a generovánívzor˚u jsou použitelnépˇr iˇr ešeníširokého spektradalších…segmentaˇc ních“aplikací.Klíˇc ováslova:dˇe leníslov,segmentace,P AT G EN,pˇr ebíjejícívzory,bootstrapping, stratifikace1MotivaceDˇe leníslov je v jádru všech aplikacípro zpracovánítext˚u.Na kvalitˇe použitého algoritmu dˇe leníslov závisímnožstvíruˇc nípráce pˇr iˇrádkovém zlomu sazby. Stáleˇc astˇe jšíjsou aplikace,kdy kontrola zlomu se neprovádív˚u bec:databázovépublikování,dávkovézpracováníXML dat m˚uže sloužit jako pˇríklad.O to vˇe tšíje poptávka po kvalitním dˇe leníslov.Obvyklépožadavky na algoritmus dˇe leníslov jsou tyto:rychlost:pˇr i optimalizaci zlomu celého odstavce naráz je potˇr eba najít dˇe lenívšech slov v odstavci.pˇr esnost:algoritmus neoznaˇcíchybnˇešvy slov pro rozdˇe lení.úplnost:algoritmus najde všechna možnádˇe leníslov.rozšiˇr itelnost:algoritmus umožníuživatelem specifikovanévýjimky–napˇrí-klad slova cizího jazyka dle pravidel dˇe lenítohoto jazyka.adaptivita:jelikožseživéjazyky vyvíjejí(nedávnáreforma pravopisu v Nˇe-mecku),je potˇr ebnénemít algoritmus…zadrátovaný“a draze optimalizo-vanýtak,že pˇr i zmˇe nˇe jazyka se musízaˇcínatúplnˇe znova.68Petr Sojkaparametrizovatelnost:algoritmus umožníjinéchovánídle charakteru použití(vúzkých sloupcích napˇríklad umožníjen dva znaky na novémˇrádku místo obvykležádaných tˇrí).minimálnípamˇe t’ovénároky:aplikace typu zalomenízpráv na displeji mobil-ního telefonu je tˇr eba navrhovat s minimálními pamˇe t’ovými,a tedy energe-tickými nároky.Základním problémem tedy je vytvoˇr it algoritmus pro zvolenýjazyk,kterýv maximálnímíˇr e splˇn uje výše uvedenépožadavky.Tentoˇc lánek popisuje pˇrístup ˇr ešenítohoto problému pro slovenštinu a krátce diskutuje výsledek ve formˇe nových vzor˚u dˇe leníslov pro slovenštinu.2Stávajícístav slovenského dˇe leníslovUživatelésázecího systému T E X používajípˇr i sazbˇe výsledky dizertaˇc nípráce[16]Knuthova studenta Franka Lianga.Liang navrhl na jazyku nezávislýpopis dˇe leníslov,kterýsplˇn uje vˇe tšinu výše uvedených požadavk˚u.Dále im-plementoval program P AT G EN[17],kterýumožˇn uje tento popis generovat ze slovníku jižrozdˇe lených slov.Brzy po rozšíˇr eníT E Xu doˇCeskoslovenska zaˇc ala být otázka dˇe leníaktuálnía vznikly prvníverze slovenských aˇc eských vzor˚u dˇe lení[14,15].Obˇe byly psány ruˇc nˇe,bez použitíprogramu P AT G EN.Ruˇc nˇe psanápravidla zachycujízákladnícharakteristiky dˇe lení,tedy napˇríklad slabiˇc nýprincip,definujíco je to slabika. U etymologického pˇrístupu k dˇe leníslov,kterýje respektován v britskéangliˇc tinˇe a standardizován nakladatelstvím Oxford Universitzy Press,však je témˇeˇr každéslovo výjimkou a proto jeˇc astˇe jšígenerovánívzor˚u ze slovníku.Vˇe tšina jazyk˚u však oba pˇrístupy kombinuje,ctíse zejména zlom našvech složených slov oproti slabiˇc nému principu.Hranice mezi cítˇe ním složeného slova dle jeho etymologie však m˚uže být diskutabilní:máme dˇe lit slabiˇc nˇe ro-zumˇc i…etymologicky“a konzervativnˇe roz-um?Pro detailnívysvˇe tleníprincipu pˇr ebíjejících vzor˚u odkazujeme na[13,pˇrí-loha H]a naˇc lánky[2,22,3].Zjednodušenˇeˇr eˇc eno,vzory specifikujíkontextovápravidla,kterámezi sebou soutˇežío každou mezipísmennou pozici ve slovˇe, a urˇc ují,zda na nídˇe litˇc i ne.Pravidla specifikujína základˇe r˚u znˇeširokého kontextu výjimky,výjimky z výjimek,....Vzájemnˇe se pˇr ebíjejí–m˚uže existovat nˇe kolikúrovnípriorit vynuceníˇc i potlaˇc enídˇe leníslova.Vítˇe zí…nejsilnˇe jší“pra-vidlo(s nejvyššíprioritou)pro každou pozici ve slovˇe:k pozici se m˚uže vyjádˇr it pravidlo v každéúrovni.Stávajícíverze slovenských vzor˚u dˇe leníexistuje ve verzi2.0z24.4.1992 (soubor skhyph.tex):\patterns{%samohl\’asky a1\’a1\"a1e1...%dvojice spoluhl\’asokSlovenskévzory dˇe leníslov:ˇc as pro zmˇe nu?692b1b2b1c2b1\v c2b1d2b1\v d...%6spoluhl\’asok3c4v4r4n3g4n3\v s4k4v4r4k3n3\v s4k4v4\’r4k3n%koncovka-n\’yk4\v c3n\’y.k4\v c3n\’eho.k4\v c3n\’emu.k4\v c3nom.%slovn\’e z\’aklady 5alkoholauto4rkauto4rs5b4lah5b4ledn 5b4lesk...%koncovky4b4s4\v t.8c4h.8d4z.8d4\v z.4c4ht4.4j4s4\v t.4lt.4m4p4r....%cudzie slov\’a akci3a2akv\’ari3u2m gymn\’azi3umle2u3k\’emiat2ri3u2mfkli3e2nt}Z komentáˇr˚u ve vzorech je vidˇe t,jakým zp˚u sobem vzory vznikaly.Po rozge-nerovánívzor˚u popisujících slabiku jako sekvenci pˇríslušného poˇc tu souhlásek a samohlásek se vzory autorka snažila zachytit slabiˇc névýjimky na zaˇcátku a konci slov a pˇr i dˇe lenícizích slov.Lze si ale tˇežko pˇr edstavit,že by se tímto zp˚u sobem podaˇr ilo zachytit nˇe kolik milión˚u slovních tvar˚u,kteréve slovenštinˇe existují. Našvech pˇr edpon a složených slov jsou mnohévýjimky,kteréjdou proti základ-nímu slabiˇc nému principu.Tˇe ch jsou ale tisíce,ˇc i desetitisíce,a jen s enormním úsilím by se daly vypsat všechny.Proˇc eštinu byly sepsány Hallerem[10],pro slovenštinu však patrnˇe takovýsoupis neexistuje.Na archívu CTAN lze nalézt vzory vytváˇr enéjak ruˇc nˇe výše popsaným zp˚u sobem,tak automaticky z jižrozdˇe leného slovníku slov daného jazyka.Tento postup máz hlediska požadavk˚u vytˇc ených vúvoduˇc lánku mnohévýhody oproti ruˇc nˇe vytvoˇr enéverzi.Pˇrístupy se takédajíkombinovat:k ruˇc nˇe zadanémnožinˇe základních vzor˚u se dogenerujívzory pro výjimky.Nebo naopak ex post nalezenévýjimky se dajík jižvygenerovaným vzor˚u m pˇr idat jako slova–vzory s nejvyššíprioritou(úrovní),tedy rozum jako.r8o8z9u8m..3Generovánívzor˚u ze slovníku rozdˇe lených slov Problematice generovánívzor˚u na semináˇr i S L T jižbyl vˇe novánˇc lánek[1],proto zopakujeme jen hlavníprincipy a laskavéhoˇc tenáˇr e odkážeme dále na dalšíˇc lánky vˇe novanététo a pˇríbuznéproblematice[11,25,20,21].Generováníprobíháve fázích,kterése nazývajíúrovnˇe(anglicky levels). V lichýchúrovních se generujípokrývacívzory,tedy vzory,kterédle kontextu znak˚u vynucujídˇe lení,v sudýchúrovních se dˇe lenídle kontextu zakazuje.70Petr SojkaGenerovanévzory se kumulují,a výslednéchováníurˇc uje výslednámnožina vzor˚u vygenerovanáve všechúrovních.U vˇe tšiny generovaných vzor˚u pro dˇe leníslov v užívaných jazycích staˇcíˇc tyˇr iúrovnˇe,ale pro pˇr ehlednost,ale takénedostatekˇc asu vzory optimalizovat,je v ruˇc nˇe chystaných vzorechúrovnímnohem více–souˇc asnéslovenskévzory jich majínapˇríklad osm.Technologie pˇr ebíjejících vzor˚u je natolik obecná,že jejípoužitíje možnépro vˇe tšinu segmentaˇc ních problém˚u.Jako pˇríklad m˚uže sloužit problematika segmentaceˇr etˇe zce thajských znak˚u na slova–v thajském textu nejsou slova oddˇe lena mezerami[23].4Bootstrapping a stratifikaceV rámci bakaláˇr sképráce[18]se podaˇr ilo shromáždit z r˚u zných zdroj˚u1 témˇeˇr milión slovenských slov.Dnešnívýpoˇc etníkapacity umožˇn ujígenerovat vzory dˇe leníi z takto rozsáhlých slovník˚u v dobách desítek minut.ˇCasovˇe nejnároˇc nˇe jšíoperaci–rozdˇe leníslovníku slov pravidly daného jazyka–lze dˇe lat pomocípˇr edchozíverze vzor˚u a místa dˇe leníslov…pouze“zkontrolovat.Jelikožvšak i tato kontrola jeˇc asovˇe nároˇc ná,lze parametry generovánívhodnou heuristikou volit tak,že vygenerovaných vzor˚u nepokrytých slov je právˇe tolik, kolik je reálnéjich v rozumnédobˇe ruˇc nˇe zkontrolovat.To znaˇc nˇe urychluje vývoj nových vzor˚u technikou bootstrappingu.Tabulka1.Výsledky jednéiterace bootstrappingu slovenského dˇe leníze slov-níku822878slovúroveˇn dobˇr ešpatnˇe chybí#vzor˚u velikost1Bohužel výslednou množinu slov nelze volnˇešíˇr it.Volnˇe pˇrístupnýseznam slov by umožnil ještˇe mnohemflexibilnˇe jšívytváˇr enívariant dˇe licích vzor˚u optimalizovaných pro konkrétníprojekty.Slovenskévzory dˇe leníslov:ˇc as pro zmˇe nu?71 ještˇe v tomto stoletíjedno celéˇcísloˇc asopisu TUG BOAT.Patrnˇe z d˚u vodu zpˇe tnékompatibility nejsou tyto vzory nahrazeny kvalitnˇe jšími,byt’kompatibilita je pˇr i pˇr idánívýjimek do vzor˚u ve formátu stejnˇe porušena.Dnešnívýpoˇc etnítech-nika jižumožˇn ujeˇc etnéexperimenty a generováníopakovat s r˚u znými parame-try.Vhodnými heuristikami nastaveníprah˚u akceptace adept˚u vzor˚u v jednotli-výchúrovních generováníse lze dostat na mnohem kvalitativnˇe vyššíparametry vzor˚u,nežkterédocílil pˇr ed témˇeˇrˇc tvrtstoletím Liang.Typicky je možnéza cenu mírného zvýšenívelikosti vzor˚u docílit stoprocentního pokrytíuˇcícímnožiny, nebo naopak pˇr i zadánívelikostních omezenína velikost vzor˚u lze maximalizo-vat pokrytí.A to vše s nulovou chybovostía stejnými konstantními výpoˇc etními nároky pˇr i aplikaci vzor˚u.Jinakˇr eˇc eno,poˇc et instrukcína nalezenídˇe licíchšv˚u slova je ohraniˇc en shora konstantou,nezávisle na tom,z jak velkého slovníku vzory generujeme.Dalšítechnikou,kteráse dápˇr i generovánívzor˚u použít,je stratifikace.Tato technika spoˇcíváv tom,že se snažíme minimalizovat množinu slov k uˇc ení, anižbychom ale pˇr išli o funkˇc nost vzor˚u na výjimkách.Máme-li napˇríklad slovník generovanýmorfologickým analyzátorem,tedy známe od každého slovního tvaru slovnízáklad,staˇcído slovníku slov zahrnout náhodnˇe pouze pár slovních tvar˚u od jednoho lemmatu.Dˇe leníkoncovek se zgeneralizuje,nebot’koncovkovémnožiny se neustále opakujía uˇcícíalgoritmus bude mít dostatek uˇcících pˇríklad˚u,aby se pravidelnosti dˇe leníkonc˚u slov nauˇc il.Naopak se nesmív seznamu uˇcících slov zapomenout na negace a pˇr edpony.Dˇe leníza prvníslabikou slov zaˇcínajících na na-naj-,pre-pred-apod.je nutno nahlížet jako na výjimky.5Shrnutí:ˇc as pro zmˇe nu?Bylo vytvoˇr eno nˇe kolik variant nových vzor˚u dˇe lenípro slovenštinu.Vzory jsou pro testováník dispozici ve FTP archívu CSTUGu v adresáˇr i cstug/sojka/skhyp. Po nezbytnéfázi testovánípˇr edpokládáme jejich zaˇr azenído bˇežných T E Xových distribucía projektu O PEN O a budoušíˇr eny bez omezujících licenˇc-ních podmínek.Jelikožzmˇe na vzor˚u dˇe lenípravdˇe podobnˇe zp˚u sobízmˇe nu zalomeníjižvytvoˇr ených dokument˚u,je tˇr eba být v pˇrípadˇe rozšíˇr eného požadavku na zpˇe tnou kompatibilitu obezˇr etný.Jelikožna zálohováníúplných zdroj˚u vˇc etnˇe zdroj˚u potˇr ebných na generováníformátu se obvykle zapomíná,pˇr i požadavku zpˇe tnékompatibility je tˇr eba zvážit všechna pro i proti a novévzory si tˇr eba zavést jako novýjazyk(\language)spolu se starými.Jsme pˇr esvˇe dˇc ení,žeˇc as pro zmˇe nu po více neždekádˇe používánísouˇc asných vzor˚u nastal a kvalita nových vzor˚u je dostateˇc ným argumentem pro zavedenízmˇe ny.Po téjižostatnˇe nˇe kolik let volajítakéuživateléO PEN O a dalších sázecích systém˚u, kteˇrídosud používajístarévzory dˇe lení.72Petr SojkaReference1.David Antoša Petr Sojka.Generovánívzor˚u dˇe leníslov v UNICODE.V Kasprzak aSojka[12],strany23–32.2.David Antoša Petr Sojka.Pattern Generation Revisited.V Pepping[19],strany7–17.3.David Antoša Petr Sojka.Generovánívzor˚u pomocíknihovny P AT L IB a programuOP AT G EN.Zpravodaj C S TUG,12(1):3–12,2002.4.Barbara Beeton.Hyphenation exception log.TUGboat,5(1):15,kvˇe ten1984.5.Barbara Beeton.Hyphenation exception log.TUGboat,6(3):121,listopad1985.6.Barbara Beeton.Hyphenation exception log.TUGboat,7(3):146–147,ˇríjen1986.7.Barbara Beeton.Hyphenation exception log.TUGboat,10(3):336–341,listopad1989.8.Barbara Beeton.Hyphenation exception log.TUGboat,13(4):452–457,prosinec1992.9.Pat Hall a Durgesh D Rao,editoˇr i.Proceedings of EACL2003Workshop onComputational Linguistics for South Asian Languages–Expanding Synergies with Europe,duben2003.10.JiˇríHaller.Jak se dˇe líslova.StátnípedagogickénakladatelstvíPraha,1956.11.Yannis Haralambous.A Small Tutorial on the Multilingual Features of PATGEN2.dostupnéna CTAN jako info/patgen2.tutorial,leden1994.12.Jan Kasprzak a Petr Sojka,editoˇr i.SLT2001,Brno,Czech Republic,únor2001.Konvoj.13.Donald E.Knuth.The T E Xbook,volume A of Computers and Typesetting.Addison-Wes-ley,Reading,MA,USA,1986.14.Jana Chlebíková.Ako rozdˇe lit’(slovo)ˇCeskoslovensko.Zpravodaj C S TUG,1(4):10–13,1991.dislav Lhotka.ˇCeskédˇe lenípro T E X.Zpravodaj C S TUG,1(4):10–13,1991.16.Franklin M.Liang.Word Hy-phen-a-tion by Com-put-er.PhD thesis,Department ofComputer Science,Stanford University,USA,srpen1983.17.Franklin M.Liang a Peter Breitenlohner.PAT tern GEN eration program for the T E X82hyphenator.dokumentace programu PATGEN verze2.3z distribuce web2c na CTAN, 1999.18.Ján Lieskovský.Systém pro práci se seznamy slov.Bakaláˇr skápráce,Masarykovauniverzita v Brnˇe,Fakulta informatiky,2003.19.Simon Pepping,editor.EuroT E X2001,Kerkrade,The Netherlands,záˇrí2001.NTG.20.Petr Sojka.Notes on Compound Word Hyphenation in T E X.TUGboat,16(3):290–297,1995.21.Petr Sojka.Hyphenation on Demand.TUGboat,20(3):241–247,1999.22.Petr peting Patterns for Language Engineering.V Sojka et al.[24],strany157–162.23.Petr Sojka a David Antoš.Context Sensitive Pattern Based Segmentation:A ThaiChallenge.V Hall a Rao[9].24.Petr Sojka,Ivan Kopeˇc ek,a Karel Pala,editoˇr i.Proceedings of the Third InternationalWorkshop on Text,Speech and Dialogue—TSD2000,Lecture Notes in Artificial Intelligence LNCS/LNAI1902,Brno,záˇrí2000.Springer-Verlag.25.Petr Sojka a PavelŠeveˇc ek.Hyphenation in T E X–Quo Vadis?TUGboat,16(3):280–289,1995.。
公共地的悲剧
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——公共地的“杯具”
第三小组
制作人:陈旭、曾萧霄 讲解人:曾萧霄
亚里士多德曾说: “那由最大人 数所共享的事物,却 只得到最少的照顾”。
这就是公共地的悲剧
“公共地悲剧”(Tragedy of the commons)是一种涉及个人利益与公共利益 (Common good)对资源分配有所冲突的社会陷 阱(Social trap)。
得个人最优饲养量 g
* i
此时,养一只羊的边际收益等于边际成 本,牧民不会增加羊的数量
上述n个一阶条件定义了n个反应函数:
g gi ( g1,…,gi 1,gi 1,…,g n )
* i
i =1, 2…,n
由于:
2 i v(G)+v(G) gi v(G) 0 2 gi
2 i v(G)+gi v(G ) 0 g j gi
所以:
gi 2 0 i g j gi2
i g j gi
2
gi 0 g j
这说明了,第 i 个农民的最优 饲养量随其他农民的饲养量的增 加而递减.
因此,n个反应函数的交叉点就是 纳什均衡:
可能用到的证明:
① ②
而对于一个村庄整体来说,可持续发展得羊的放牧数量要考虑最大化的 社会收益: 其中G**为可持续发展得羊的理想放牧数量。 ①式和②式都说明,增加一只羊进行放牧时有两方面的作用:一方面是 成员增加了收益v(G),另一方面是这一只羊的增加导致的以前羊的收益的下 降[v′(G)<0]。不同的是,①式中成员只考虑对自己的负效应,而不顾及 其他社会成员,而②式中充分考虑了全部羊的数量的社会成本。 我们先假定G*≤ G**,即羊的现实放牧数量低于羊的理想放牧数量,先 将①式和②式合并得: *
公地悲剧用来说明
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公地悲剧用来说明公地悲剧,又称为“公地灾难”,是指在相对贫穷的社会当中,由于政府政策的失误、或是贫困人民被赶出家园,而落实致使贫穷人口因无家可归而死亡或因此造成的悲剧。
在发展中国家,公地悲剧经常发生,已经成为为发展中国家不可避免的社会问题。
公地悲剧的发生,主要的原因是政府误导的贵族政策和以财富为中心的社会无穷利用。
一旦社会脱离和平,政府就会招致统治自己的贵族,增加政府的经费,消耗社会经济资源,增加社会问题。
由于当地政府只为统治贵族而存在,他们没有考虑普通百姓的福祉,对贫穷的百姓们的诉求置若罔闻,很多贫穷的农民甚至被迫从家中赶走,无家可归。
其次,由于社会资源分配不均,财富的收集、存储和分配都被以财富为中心的贵族所占据,贫穷的农民也被强行剥夺,造成贫富悬殊,贫穷的农民更加困难,无家可归,最终出现公地悲剧。
公地悲剧是一种社会问题,给发展中国家带来了恶劣的社会影响。
一方面,公地悲剧给贫困人民带来了身心上的伤害,他们失去了家园,无家可归,有的甚至死亡。
另一方面,由于缺乏基础设施,贫困人口容易滋生疾病,病毒传播得更加快速,社会生病率不断增加,最终导致社会健康水平下降,给发展中国家带来沉重压力。
因此,政府有责任采取有效措施,确保人民的基本权利,营造公平正义的社会环境,加强人口负责任的观念,以及加强贫困地区的经济开发,打击公地悲剧,保障人民的基本生活权利,让贫穷人们有家可归,让他们有希望的生活。
总的来说,公地悲剧是深刻地反映了发展中国家社会问题的恶劣状况,其后果和影响都十分严重。
因此,发展中国家应该加强贫困地区的经济开发,采取各种措施来预防公地悲剧,保障农民和贫困地区人民的基本权利,让农民有尊严的生活。
只有在全社会的努力下,才能真正的解决和根除公地悲剧,让发展中国家大步提高社会经济水平,实现和谐社会的发展。
Tagedy of the commons
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∙正面:牧羊人可以从增加的羊只上获得所有的利润∙负面:牧场的承载力因为额外增加的羊只有所耗损至于如何避免过度消耗公地,哈丁以恩格斯的论述做出结论,他认为“自由是需求的确认”,他表示若将自由狭义的解释为任意的自由,将使公地悲剧理论更加完整。
但Hardin相信,若能在一开始就确认资源之为公地,并对其有所觉醒,了解公有资源是需要受到规范的,那么“人类将能保有并且培育出更珍贵的自由”。
除了资源使用的主要论述之外,此篇论文另一个值得注意的地方在于他明确的处理和道德相关的问题,并将其投稿于科学期刊《科学》。
而期刊为这篇文章所下的标题为“人口成长所带来的问题并没有科学的解决方法,而需要一个基本的道德延展”。
公地悲剧直到今日仍存有争议。
有些争议起源于个体是否永远如Hardin所言的自私。
更值得注意的是,有些争议来自于将Hardin的意见实践于真实情况中。
有些专家甚至认为Hardin的作品提倡公地的私有化。
进而导致了原本由当地机构管制的公地被圈管或私有化。
表面上这样的措施看似保护了资源,实际上却忽略了预存的管理通常不公平的盗用资源,并且隔离了原本就存在于资源所在的(通常是贫穷的)人群。
当哈丁的论文聚焦于不受管理的资源而非公有管理的资源时,他的诉求却是不合时宜的。
讽刺的是,对于Hardin想法的误解通常来自于他的牧场理论。
大体而言,Hardin清楚的描述如何控管公有财产以避免资源的过度消耗。
但他对于公有资产的定义与管理方式常常被误解为提倡私有化的论述。
而相对于公地悲的论则通常被视为“反公地悲剧”意指:理性的个体浪费资源。
[编辑]历史上的公地哈丁的论文为“公地”一词提出了一个假设性的类比。
在这个类比中,牧羊人使用牧场是基于个体的自由行动,而没有群体的管理与监督。
然而,事实上历史上的公地并非公有地,且多数不对外开放,所谓的公众其实掌有极小的权利。
只有那些原本就存在于资源之上的人们才算是共享者,也才能拥有多数的权利;而每一个共享者都有自身的权利,但公地本身并不是资产。
recent initiaatives by the basel-based r_qt0806
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BIS Quarterly ReviewJune 2008 International banking and financial market developmentsBIS Quarterly ReviewMonetary and Economic DepartmentEditorial Committee:Claudio Borio Frank Packer Paul Van den BerghWhite Már Gudmundsson Eli Remolona William Robert McCauley Philip TurnerGeneral queries concerning this commentary should be addressed to Frank Packer(tel +41 61 280 8449, e-mail: frank.packer@), queries concerning specific parts to theauthors, whose details appear at the head of each section, and queries concerning the statisticsto Philippe Mesny (tel +41 61 280 8425, e-mail: philippe.mesny@).Requests for copies of publications, or for additions/changes to the mailing list, should be sent to:Bank for International SettlementsPress & CommunicationsCH-4002 Basel, SwitzerlandE-mail: publications@Fax: +41 61 280 9100 and +41 61 280 8100This publication is available on the BIS website ().©Bank for International Settlements 2008. All rights reserved. Brief excerpts may be reproduced or translated provided the source is cited.ISSN 1683-0121 (print)ISSN 1683-013X (online)BIS Quarterly ReviewJune 2008International banking and financial market developmentsOverview : a cautious return of risk tolerance (1)Credit market turmoil gives way to fragile recovery (1)Box: Estimating valuation losses on subprime MBS with theABX HE index – some potential pitfalls (6)Bond yields recover as markets stabilise (8)A turning point for equity prices? (11)Emerging market investors discount growth risks (12)Tensions in interbank markets remain high (13)Highlights of international banking and financial market activity (17)The international banking market (17)The international debt securities market (23)Derivatives markets (24)Box: An update on local currency debt securities marketsin emerging market economies (28)Special featuresInternational banking activity amidst the turmoil (31)Patrick McGuire and Goetz von PeterThe build-up of international bank balance sheets (32)Developments in the second half of 2007 (36)Bilateral exposures of national banking systems (39)Concluding remarks (42)Managing international reserves: how does diversification affect financial costs? 45 Srichander RamaswamyFramework of the analysis (46)Risk-return trade-offs (48)Financial cost of acquiring reserves through FX intervention (49)Box: Methodology for computing estimates of financial cost (51)Central bank objectives and FX reserve allocation (53)Conclusions (54)Credit derivatives and structured credit: the nascent markets of Asiaand the Pacific (57)Eli M Remolona and Ilhyock ShimCredit default swaps (58)Traded CDS indices (60)Collaterised debt obligations (61)How the region’s markets have fared in the global turmoil (63)Conclusion (65)Asian banks and the international interbank market (67)Robert N McCauley and Jens ZukunftAsian banks’ international interbank liquidity: where do we stand? (68)Foreign banks and the local funding gap (73)Box: The Asian financial crisis: international liquidity lessons (76)Conclusions (78)BIS Quarterly Review, June 2008 iiiRecent initiatives by Basel-based committees and groupsBasel Committee on Banking Supervision (81)Joint Forum (84)Financial Stability Forum (87)Statistical Annex ........................................................................................ A1 Special features in the BIS Quarterly Review ................................ B1 List of recent BIS publications .............................................................. B2Notations used in this Reviewe estimatedlhs, rhs left-hand scale, right-hand scalemillionbillion thousand… notavailableapplicable. not– nil0 negligible$ US dollar unless specified otherwiseDifferences in totals are due to rounding.iv BIS Quarterly Review, June 2008BIS Quarterly Review, June 20081Ingo Fender +41 61 280 8415ingo.fender@Peter Hördahl+41 61 280 8434peter.hoerdahl@Overview: a cautious return of risk toleranceFollowing deepening turmoil and rising concerns about systemic risks in the first two weeks of March, financial markets witnessed a cautious return of investor risk tolerance over the remainder of the period to end-May 2008. The process of disorderly deleveraging which had started in 2007 intensified from end-February, with asset markets becoming increasingly illiquid and valuations plunging to levels implying severe stress. However, markets subsequently rebounded in the wake of repeated central bank action and the Federal Reserve-facilitated takeover of a large US investment bank. In sharp contrast to these favourable developments, interbank money markets failed to recover, as liquidity demand remained elevated.Mid-March was a turning point for many asset classes. Amid signs of short covering, credit spreads rallied back to their mid-January values before fluctuating around these levels throughout May. Market liquidity improved, allowing for better price differentiation across instruments. The stabilisation of financial markets and the emergence of a somewhat less pessimistic economic outlook also contributed to a turnaround in equity markets. In this environment, government bond yields bottomed out and subsequently rose considerably. A reduction in the demand for safe government securities contributed to this, as did growing perceptions among investors that the impact from the financial turmoil on real economic activity might turn out to be less severe than had been anticipated. Emerging market assets, in turn, performed broadly in line with assets in the industrialised economies, as the balance of risk shifted from concerns about economic growth to those about inflation.Credit market turmoil gives way to fragile recoveryFollowing two weeks of increasingly unstable conditions in early March, credit markets were buoyed by a cautious return of risk tolerance, with spreads recovering from the very wide levels reached during the first quarter of 2008. Sentiment turned in mid-March, following repeated interventions by the Federal Reserve to improve market functioning and to help avert the collapse of a major US investment bank. As these actions alleviated earlier concerns about risks to the financial system, previously dysfunctional markets resumed trading and prices rallied across a variety of risky assets.2BIS Quarterly Review, June 2008Between end-February and end-May, the US five-year CDX high-yield index spread tightened by about 144 basis points to 573, while corresponding investment grade spreads fell by 63 basis points to 102. European and Japanese spreads broadly mirrored the performance of the major US indices, declining by between 25 and 153 basis points overall. Between 10 and 17 March, all five major indices had been pushed out to or near the widest levels seen since their inception. They then rallied back and seemed to stabilise around their mid-January values, remaining significantly above the levels prevailing before the start of the market turmoil in mid-2007 (Graph 1).business lines, tightening repo haircuts caused a number of hedge funds and other leveraged investors to unwind existing positions. As a result, concerns underlying exposures are almost entirely protected by federal guarantees, as summer of 2007 (Graph 3, right-hand panel).BIS Quarterly Review, June 20083Fears about collapsing financial markets reached a peak in the week March, triggering repeated policy actions by the US authorities. investment grade credit default swap (CDS) indices underperforming lower-quality benchmarks (Graph 4, left-hand and centre panels). Spreads were temporarily arrested when, on 11 March, the Federal Reserve announced an expansion of its securities lending activities targeting the large US dealer banks (see section on money markets and Table 1 below). European CDS indices tightened by more than 10 basis points on the news, while the two key basis points down, respectively (Graph 1). allowing it to make secured advance payments to the troubled investment These developments appeared to herald a turning point in the market, funds target down to 2.25%. Earnings announcements by major investment banks on 18 and 19 March that were better than anticipated provided further support, with investors increasingly adopting the view that various central bank initiatives aimed at reliquifying previously dysfunctional markets were gradually gaining traction. Consistent with perceptions of a considerable reduction in systemic risk, spreads, and particularly those for financial sector and other investment grade firms, tightened from the peaks reached in early March(Graph 4). Movements were partially driven by the unwinding of speculative short positions, as suggested by changes in pricing differentials across products with similar exposures, according to the ease with which such positions can be opened or closed. For example, spreads on CDS contracts referencing the major credit indices moved more strongly than those on the same indices’ constituent names (Graph 1, centre and right-hand panels). Similarly, CDS markets outperformed those for comparable cash bonds, as market participants adjusted their synthetic trades.risks (Graph 1, centre and right-hand panels). Similarly, implied volatilities from CDS index options eased into the second quarter, indicating a somewhat reduced uncertainty about shorter-run credit spread movements (Graph 3, centre and right-hand panels).losses based on ABX prices (see box). This was despite the lack of a recovery for the index series with lower original ratings, whose prices continued to4 BIS Quarterly Review, June 2008BIS Quarterly Review, June 20085suggest expectations of complete writedowns of all underlying bonds by mid-2009 (Graph 2, centre panel). At these low levels, and with none of the ABX indices having experienced any principal writedowns so far, investors appeared to be pricing in the possibility of legislation writing down mortgage principal. Against this background, issuance of private-label mortgage-backed securities remained depressed, with volume growth coming mainly from US agency-Supported by optimism about banks’ recapitalisation efforts, spreads pace of capital replenishment. Following news of a rights issue on 31 March, CDS spreads referencing debt issued by Lehman Brothers tightened. UBS announced large first quarter losses and a fully underwritten capital increase on 1 April, and other institutions followed over the rest of the month. Globally, banks managed to raise more than $100 billion of new capital in April alone, stemming the deterioration in capital ratios. Financial CDS spreads, the monoline segment excluded, outperformed corresponding equity prices in the process (Graph 4, right-hand panel), reflecting diminishing concerns about imminent financial sector risk as well as the dilutory effects of equity financing. Markets retraced some of these gains in early May, partially driven by strong supply flows from corporate issuers that included, at $9 billion, the largest US dollar deal by a non-US borrower in seven years. Volumes were dominated by6 BIS Quarterly Review, June 2008Pitfalls in using the ABX. Estimated mark to market losses and actual writedowns made by banks and other investors can differ for a variety of reasons. Analysts, depending on their objective, thus have to be mindful of potential sources of bias. At least three such sources can be identified, of which two are specific to the ABX index:•Accounting treatment. Subprime MBS are held by a variety of investors and for different purposes. While large amounts of outstanding subprime MBS are known to reside inbanks’ trading books, banks and other investors may also hold these securities tomaturity. This can result in different accounting treatments, which would tend to deflateactual writedowns and impairment charges relative to estimates of mark to market losseson the basis of market indices, such as the ABX. The size of this effect, however, isdifficult to determine. Further complexities are added once securities cease to be tradedin active markets, implying the use of valuation techniques, which may differ acrossinvestors, in establishing fair value.5•Market coverage. ABX prices may not be representative of the total subprime universe, due to limited index coverage of the overall market. Original balance across all four serieshas averaged about $31 billion. This compares to average monthly MBS issuance ofsome $36 billion over the 10 quarters up to mid-2007, ie almost a month’s worth ofsubprime MBS supply per index series. Similarly, with 2004–07 vintage subprime MBSvolumes estimated at around $600 billion in outstanding amounts, each series representssome 5% of the overall universe on average. At the same time, ABX deal composition isknown to be quite similar in terms of collateral attributes (such as FICO scores and loan-to-value ratios) to the overall market (by vintage).6 Therefore, despite somewhat limitedcoverage, this particular source of bias may not be large.•Deal-level coverage. Similarly, ABX prices may not be representative because each index series covers only part of the capital structure of the 20 deals included in the index(see Graph A, right-hand panel, for an illustration).7 In particular, tranches referenced bythe AAA indices are not the most senior pieces in the capital structure, but those with thelongest duration (expected average life) – the so-called “last cash flow bonds”. Theseclaims will receive any cash flow allocations sequentially after all other AAA trancheshave been paid; and tend to switch to pro rata pay only when the highest mezzaninebond has been written down. It follows that AAA ABX index prices are going to reflectdurations that are longer, and effective subordinations that are lower, than those of theremaining AAA subprime MBS universe. As a result, using newly available data for MBStranches with shorter durations, the $119 billion of losses implied by the ABX AAA indicesas of end-May would be some 62% larger than those implied under more realisticassumptions.8_________________________________1 See, for example, International Monetary Fund, Global Financial Stability Report, April 2008, pp 46–52, and Box 1 in Bank of England, Financial Stability Report, April 2008.2 Supplementary indices, called ABX HE PENAAA, were introduced in May 2008 to provide additional pricing information for all four existing vintages.3 An alternative approach, likely to lead to very different results, would estimate future default-related cash flow shortfalls on the basis of deal-level or aggregate data for subprime securities. To obtain these estimates, such methodologies rely on information about collateral performance and require the analyst to make assumptions about structural relationships and model parameters. Typical subprime loss projections, for example, use delinquency data and assumptions about factors such as delinquency-to-default transitions, default timing, and losses-given-default. See Box 1 in the Overview section of the December 2007 BIS Quarterly Review for an example on the basis of an approach devised by UBS. 4Mark to market losses (relative to par) are calculated assuming that unrated tranches are written down completely; ABX prices for the BBB– indices are used to mark BB collateral; rated tranches from the 2004 vintage are assumed unimpaired; outstanding amounts remain static.5 For details, see Global Public Policy Committee, Determining fair value of financial instruments under IFRS in current market conditions, December 2007.6 See, for example, UBS, Mortgage Strategist, 17 October 2006. 7 Incomplete coverage at the deal level further reduces effective market coverage: typical subprime MBS structures have some 15 tranches per deal, of which only five were originally included in the ABX indices. As a result, each series references less than 15% of the underlying deal volume at issuance.8 Duration effects at the AAA level are bound to be significant for overall loss estimates as the AAA classes account for the lion’s share of MBS capital structures. Using prices for the newly instituted PENAAA indices, which reference “second to last” AAA bonds, to calculate AAA mark to market losses generates an estimate of $73 billion. This, in turn, translates into an overall valuation loss of $205 billion (ie some 18% below the unadjusted estimate of $250 billion).capitalisation had recovered, while remaining weaker than before the crisis. At the same time, still-elevated implied volatilities suggested ongoing investor uncertainty over the future trajectory of credit markets. With the credit cycle continuing to deteriorate and related losses on exposures outside the residential mortgage sector looming, it was thus unclear whether liquidity supply and risk tolerance had recovered to an extent that would help maintain this improved environment on a sustained basis.Bond yields recover as markets stabiliseFrom its low point on 17 March, the 10-year US Treasury bond yield rose by 75 basis points to reach 4.05% at the end of May. During this period, 10-year yields in the euro area and Japan climbed by around 70 and 50 basis points, respectively, to 4.40% and 1.75% (Graph 5, left-hand panel). In US and euro area bond markets, the increase in yields was particularly pronounced for short maturities, with two-year yields rising by 130 basis points in the United States and by almost 120 basis points in the euro area (Graph 5, centre panel). Two-year yields went up in Japan too, but by a more modest 35 basis points. In addition to reduced safe haven demand for government securities, the rise in short-term yields reflected a reassessment among investors of the need for monetary easing, following the stabilisation of financial markets.In the first two weeks of March, as the financial turmoil deepened and forward rates dropping (Graph 6, right-hand panel). While flight to safety and other effects relating to the volatility in financial markets may have influenced consistent with the observed fall at the short end of the forward break-evencurve. At the same time, these same concerns led investors to increasinglyexpect the Federal Reserve to maintain a more accommodative policy stancethan normal in an effort to contain the fallout on economic growth. Insofar asthis was seen as likely to lead to higher prices down the road, it could explainthe rise in distant forward break-even rates at the time.As the situation in financial markets stabilised after the rescue of BearStearns in mid-March, and perceptions of the economic outlook improvedsomewhat, the US forward break-even curve shifted in the opposite directionand flattened considerably. To a large extent, this shift in the forward curve islikely to have reflected a reversal of the same influences that had been at playin the first two weeks of March: the dampening effect on prices coming from theturmoil was perceived to be weaker after mid-March, while the Federal Reservewas seen to be less likely to deliver further sharp rate cuts. Moreover, upwardprice pressures appeared to intensify in the short to medium term, with foodprices rising continuously and oil prices reaching new all-time highs during thisperiod (Graph 5, right-hand panel), pushing near-term forward break-evenrates further upwards.real yields reflected a combination of expectations of higher average realinterest rates in coming years and a reversal of flight to safety pressures. Theformer component, in turn, was due to perceptions among investors that thereal economic fallout from the financial turmoil was likely to be less severe thanhad previously been anticipated. This was despite indications of deterioratingconsumer confidence amid tighter bank lending standards and continuedweakness in US housing markets. The revival in investor confidence seemedinstead to follow from the stabilisation in markets and from a number ofrelatively upbeat macroeconomic announcements. These included better thangovernment securities.In line with perceptions that the stabilisation of markets had reduced therisks to economic growth somewhat, prices of short-term interest rateindicating expectations of a period of stable rates, followed by rising rates inthe first half of 2009 (Graph 7, left-hand panel). In the euro area, EONIA swapprices at the beginning of March had signalled expectations of sizeable ECBrate cuts, but by end-May prices had shifted to reflect expectations of graduallyincreasing policy rates (Graph 7, centre panel). Meanwhile in Japan,expectations of mildly falling policy rates in March had by May been revised toindicate rising rates (Graph 7, right-hand panel).A turning point for equity prices?to end-2007 levels, gained almost 10% between 17 March and end-May. Equity markets in Europe and Japan, which had seen losses in excess of 20% between the turn of the year and 17 March, subsequently also displayed a strong recovery, with the EURO STOXX gaining 11% and the Nikkei 225 rising Reflecting the improved situation in financial markets during this period, by almost 20% and 34%, respectively. These gains occurred despiteannouncements by several banks of record losses during the first quarter amidcontinued credit-related write-offs. Investors obviously took solace from the factthat losses – although big – were no worse than expected, and that a numberof banks had been successful in their recapitalisation efforts (see credit marketsection above).surprises remained well above that of negative surprises, provided somesupport for equity prices. In addition, as fears failed to materialise that economic growth might slow dramatically in the first few months of the year,investors increasingly began to see equity valuations as attractive following thesharp price declines in late 2007 and early 2008. markets recovered after a sharp dip in March (Graph 8, right-hand panel).Emerging market investors discount growth risksequities fell up to mid-March, before rebounding in the wake of the change inmarket sentiment following the Bear Stearns rescue in the United States.Between end-February and end-May, the MSCI emerging market indexgained about 4% in local currency terms, and was up more than 14% from thelows established in mid-March. Latin American markets, which had seen ahigh trading volumes in commodity derivatives (see the Highlights section inthis issue) and speculative demand as a source of part of that strength, otherspointed to low supply elasticities and expectations of sustained rates ofindustrialisation throughout the emerging markets. With the region being amajor net commodities importer and natural disaster contributing to weakerequity prices in China, Asian markets were broadly flat over the period.Emerging Europe, in turn, remained exposed to the risk of a reversal in privatecapital flows, owing to large current account deficits and associated financingneeds in a number of countries. Nevertheless, strong gains in Russia and thebetter than expected growth performance of major European economies in thefirst quarter seemed to aid equity markets in May.Emerging market credit spreads, as measured by the EMBIG index,accounting for most of the spread tightening, the EMBIG remained almost flatin return terms, gaining about 1.1% between end-February and end-May(Graph 9, left-hand panel). Large stocks of foreign reserves and favourablemacroeconomic performance in key emerging market economies continued toprovide support, aiding the market recovery. Spread dispersion remained high,pointing to ongoing price differentiation according to credit quality (Graph 10,centre panel). At the same time, with inflation running well above target in anumber of major emerging market economies, policy credibility appeared tobecome more of a concern, putting pressure on local bond markets. Risinginflation expectations, combined with increasing US Treasury yields andrelatively resilient markets during the earlier stages of the recent marketturmoil, may thus have contributed to a somewhat more muted performancefrom emerging market bonds relative to other asset markets over the periodsince mid-March.Tensions in interbank markets remain highas high at the end of May as three months earlier, across most horizons and inall three major markets (Graph 10). This appeared to imply expectations thatinterbank strains were likely to remain severe well into the future.After a relatively smooth turn of the year, interbank market tensions hadappeared to ease somewhat until early March 2008, and Libor-OIS spreadshad shown some signs of stabilising. However, as the financial turmoilsuddenly deepened in the second week of March, following an acceleration inmargin calls and rapid unwinding of trades (see the credit section above),interbank market pressures quickly increased. With market rumoursproliferating about imminent liquidity problems in one or more large investmentbanks, banks became increasingly wary of lending to others. At the same time,their own demand for funds jumped as they sought to avoid being perceived ashaving a shortage of liquidity.Selected central bank liquidity measures during the period under review7 March The Federal Reserve increases the size of its Term Auction Facility (TAF) to $100 billion andextends the maturity of its repos to up to one month.11 March The Federal Reserve introduces the Term Securities Lending Facility (TSLF), which allowsprimary dealers to borrow up to $200 billion of Treasury securities against collateral. Theexisting dollar swap arrangements between the Federal Reserve and the ECB and the SNB areincreased from a total of $24 billion to $36 billion.16 March The Federal Reserve introduces the Primary Dealer Credit Facility (PDCF), which providesovernight funding for primary dealers in exchange for collateral. The Federal Reserve alsolowers the spread between the discount rate and the federal funds rate from 50 to 25 basispoints, and lengthens the maximum maturity from 30 to 90 days.28 March The ECB announces that the maturity of its longer-term refinancing operations (LTROs) wouldbe extended from up to three months to a maximum of six months.21 April The Bank of England introduces the Special Liquidity Scheme, under which banks can swapilliquid assets for Treasury bills.2 May The Federal Reserve boosts the size of its TAF programme to $150 billion, and announces abroadening of the collateral eligible for the TSLF auctions. The dollar swap arrangements withthe ECB and the SNB are increased further, from $36 billion to $62 billion.Source: Central bank press releases. Table 1The near collapse and subsequent takeover of Bear Stearns onMarch highlighted the risks that banks face in such situations. On the would not be allowed to fail, and this helped restore order in other markets. On the other hand, the speed with which Bear Stearns’ access to market liquidity had collapsed underscored the vulnerability of other banks in this regard, which kept Libor-OIS spreads high even as CDS spreads on banks and brokerages Throughout the period, central banks maintained and even stepped up activity from central banks seemed to have limited immediate impact oninterbank rates. To some extent, this may have reflected the fact that while thesums involved in central bank liquidity schemes were large in absolute terms,they were still rather limited compared to banks’ assessment of their overallliquidity needs against the background of a sharp decline in traditional sourcesof funding. One significant source of short-term funding for banks in the pasthas been money market mutual funds. Such funds have seen substantialinflows since the outbreak of the financial turmoil (Graph 11, left-hand panel),reflecting a noticeable reduction in investors’ appetite for risk. However, thisloss of risk appetite also resulted in money market funds shifting theirinvestments increasingly into treasury bills and other safe short-term securities,hence depriving banks of a key funding source (Graph 11, centre panel). Thissuggests that determining how persistent the interbank tensions will be maydepend significantly, among other things, on how long the risk appetite ofmoney market fund managers, and investors more broadly, will continue to bedepressed.。
最新公地悲剧翻译稿
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公地悲剧翻译稿哈丁:公地的悲剧(The Tragedy of the Commons)时间: 2010-10-23,人气: 609J.B. Wiesner和H.F. York在一篇关于核子战争前景的发人深省文章结尾时说:「武器竞赛的双方都是…面对持续增强的军事力量和持续减弱的国家安全。
深思之下,我们的专业意见认为这困局没有技术性的解决办法。
如果大国只是在科学和科技这方面找寻解决办法,结果只会令情况恶化。
」希望各位不要集中注意文章的主题(核武世界的国家安全),而是要留意作者的结论,即是问题没有技术性的解决办法。
专业和半通俗科学期刊的评论,差不多都隐喻评论的问题是有技术性的解决办法。
技术性解决办法可以定义为只要改变自然科学的技术,无需或只是稍为改变人的道德价值或概念。
我们现在一般都欢迎有技术性解决办法(以前并非如此)。
因为以前的预言往往失准,要有莫大勇气才会断言没有预期的技术性解决办法。
Wiesner和York表现出勇气,在科学期刊发表文章,坚持问题不能在自然科学找到解决办法。
他们小心翼翼为声明加上以下的批注:「深思之下,我们的专业意见…。
」本文所关注的。
不是他们是否正确,而是一个重要的观点:有一组关乎人的问题可以称为「没有技术性解决办法的问题」,或是更明确地说:认定和讨论这些问题是其中之一。
要表明这类问题不是空号很容易。
还记得划井游戏。
想一想:「我如何赢划井游戏?」假设(依照赛局理论的惯例)我的对手是个中能手,大家都知道我不可能赢。
换句话说,问题没有「技术性解决办法」。
要赢,我只能把「赢」的意义根本改掉。
我可以打对方的头,可以弄虚作假。
每一种我要「赢」的方法,都是某种意义上放弃了我们认知了解的游戏。
(我当然可以公开放弃—不玩。
大多数成年人都这样。
)「没有技术性解决办法的问题」有其它的命题。
我的论题:大家惯常认知的「人口问题」是这样的命题。
要说明一下大家是怎样惯常认知的。
持平的说,大多数人为人口问题苦恼,要找出方法避免人口过多的邪恶,但不放弃他们正在享受的特权。
公地悲剧 tragedy of the commons
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表现形式
• • • • •
军备竞赛 种内竞争 价格垄断 资源无序利用 各种环境污染 国有制 国有企业
“公地悲剧”展现的是一幅私人利用免费午餐 时的狼狈景象——无休止地掠夺。
• “公地悲剧”的发生机理似乎可以这样来理解: 公地悲剧发生的根源在于:“当个人按自己的方式处置公共 资源时,真正的公地悲剧才会发生。 “公地悲剧”的更准确的提法是:无节制的、开放式的、资 源利用的灾难。 • 环境污染:由于治污需要成本,私人必定千方百计企图把 企业成本外部化。这就是赫尔曼·E.戴利所称的“看不见的 脚”。“看不见的脚”导致私人的自利不自觉地把公共利 益踢成碎片。 • “公地悲剧”源于公产的私人利用方式。 • 针对如何防止公地的污染,哈丁提出的对策是共同赞同的 相互强制、甚至政府强制,而不是私有化。
1968年,美国学者Hardin在《科学》杂志上发表了一篇 题为《公地的悲剧》的文章
•
“未受规范的公地之悲剧”。公地悲剧 一文着重于解释经济、发展心理学、博弈 理论和社会学领域。有人将此视为“意外 行为”的范例,伴随着个人在复杂社会系 统中的互动所导致的悲剧结果。
Байду номын сангаас
地球资源
• Hardin的论文一开始便将注意力集中于无法借由科技 工具解决的问题之上,哈丁声称这样的问题来自于人口的 成长和地球资源的使用。 • 哈丁在《公地的悲剧》中设置了这样一个场景:一群 牧民一同在一块公共草场放牧。一个牧民想多养一只羊增 加个人收益,虽然他明知草场上羊的数量已经太多了,再 增加羊的数目,将使草场的质量下降。 牧民将如何取舍? 如果每人都从自己私利出发,肯定会选择多养羊获取收益, 因为草场退化的代价由大家负担。 每一位牧民都如此思考时,“公地悲剧”就上演了--草场 持续退化,直至无法养羊,最终导致所有牧民破产。
新世纪日本语教程初级第9-16课练习汇总
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5-9课翻译题目一. 请将下列句子译成日语。
(45分)⑴那个是钢笔,还是铅笔?⑵这个是谁的钱包?那个是小李的。
⑶花瓶在电视机的上面。
⑷汽车的前面有弟弟和妹妹。
⑸桌子上有四张纸。
⑹昨天的电影非常有趣。
⑺这个相机如果小些的话就好了。
⑻小王不像小李那么忙。
⑼昨天很冷,但是今天暖和。
⑽我们学校的图书馆又大又漂亮。
⑾小王日语好,英语也好。
⑿每个月给父母大约打三次电话。
⒀你经常在哪里做预习和复习的?⒁你每天大约学习多长时间?⒂星期天,我教高中生学习数学。
日语9~10课练习一、写出下列单词的假名或当用汉字。
戻る____洗濯____注文____卒業____喫茶店____おしえる____ほうかご____よしゅう____ごろ____かたりあう____たのしい____二、助词填空(每空限填一假名)。
1、この汽車は上海____来ました。
2、郵便局__スポーツ__新聞__買い__行きます。
3、友達__一緒に公園__散歩します。
4、週__インターネット__三回______ます。
5、弟はよく部屋__音楽を聴きます。
6、日曜日、三人の高校生__英語__教えます。
7、このビールはおいしい____、たくさん買いました。
8、その子供はいつも鉛筆__黒板__字を書きます。
三、完形填空。
1、今日は____(暑い)、天気がいいです。
2、あなたはお茶が____(飲む)たいですか。
3、明日、____(遊ぶ)に____(くる)ます。
4、あなたはよくどこで____(勉強)ますか。
5、趙さんは何時に____(起きる)ましたか。
四、阅读理解。
始めまして、私は陸華です。
中国の洛陽から来ました。
先月バスで来ました。
山田さんは私の日本人の友達です。
彼は私の大学の留学生です。
彼は先週飛行機で東京から西安へ来ました。
昨日は日曜日で、私は山田さんと一緒に高速バスで兵馬俑博物館に行きました。
午前十時にそこに着きました。
午後、四時半にタクシーで大学の寮に帰りました。
The Story of Baogong
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The Story Of Baogong Interrogate Stone邓坤军612080706048Once upon a time, there was a poor boy living really a hard life with his father dead and his mother seriously ill. Every day, early in the morning, to make a living, the poor boy had to struggle up and carry a basket of youtiaos(deep-fried dough sticks-a traditional Chinese food)running and crying: youtiao youtiao for sell, only two coppers(a form of money in ancient China)for one savory and crisp youtiao.”One lucky day, he sold out all his youtiaos. Sitting on a stone, he was so happy that he counted his coppers time and time again. It was just 100 coppers. The greasy youtiaos made his hands covered with oil and so did all the coppers. Looking at all the greasy sparking coppers, he was out of pleasure, thinking: Wow, I have got 100 coppers; I can afford mamma’s medicine now. However he was so tired, selling youtiao the whole morning, that he fell asleep the moment he reclined his head on the stone. After quite a long time, he woke up:“how can I sleep so long, I have to buy mamma medicine right now.” He stood up only to find all his coppers had gone, surprised. The boy was so anxious and sad that he can’t help crying out desperately. By this time, Baogong, followed by several retinues was passing. What kind of person Baogong was? He was an officer being called Baolaohei orHeibaogong by civilians because of his black face and beard and famous for his upright conduct and intelligence. Seeing such a sad crying boy, Baogong asked:“Come here, tell me why are you crying so sad.”:“ All my coppers earned by my youtiao have been stolen(crying). “Do you know who stole them?”“I have no idea, I fell asleep on the stone. As soon as I woke up, all coppers are disappeared(crying).”Baogong thought for a while:“I’ve got the answer, it must be the stone that stole your coppers. Let me interrogate it and order it to give back your coppers.” Hearing that Baogong was to interrogate a stone, all civilians crowded out of curious. Baogong asked the stone:“Stone,stone, did you stole the boy’s coppers?” Could a stone answer? Of course not. Baogong tried again:“Stone, Stone, answer me quickly, don’t you hear?”The stone remained silent. It couldn’t speak any word. However Baogong tried another time:“Stone, I’d beat your head up if you don’t tell me the truth.”Hearing Baogong’s words, the retinues lifted up sticks and gave the stone a really hard lesson, crying:“Answer right now.”The crowed couldn’t help laughing:“How could a stone steal coppers and speak like man?”“Civilians are always saying about Baogong’s wisdom. He proves to be an idiot.”Baogong was really angered by the crowd,:“I am interrogating the stone. How dareyou guys speak ill of me on the back? Now, all of you, give out a copper as punishment.”He asked one retinue to borrow a basin filled with water to collect the coppers. The crowd could do nothing but obediently stood in line and threw a copper into the basin one by one“Plop, plop, plop…”A man was caught the minute he threw his copper. Baogong pointed at the man:“You are the thief. It’s you that stole the boy’s coppers.”How do you know? All people around felt odd. Baogong said:“Look here, only his copper caused a layer of oil on the water. He must have steal the boy’s coppers while he was sleeping.”The thief could do nothing but to give back the boy’s coppers. The crowd were amazed. How smart Baogong was!邓坤军2011-10-30。
公共资源的悲剧(Hardin,英汉对照)
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公有资源的悲剧by Garrett HardinIn 1974 the general public got a graphic illustration of the "tragedy of the commons" in satellite photos of the earth. Pictures of northern Africa showed an irregular dark patch, 390 square miles in area. Ground-level investigation revealed a fenced area inside of which there was plenty of grass. Outside, the ground cover had been devastated.1974年,广大公众在一张地球卫星图片中看到了“公有资源的悲剧”的一个图例。
北非的图片中有一块不规则的黑色区域,面积为390平方英里。
地面调查发现了一个被围起来的区域,里面有丰富的草。
在它的外面,地被植物已经被毁坏。
The explanation was simple. The fenced area was private property, subdivided into five portions. Each year the owners moved their animals to a new section. Fallow periods of four years gave the pastures time to recover from the grazing. They did so because the owners had an incentive to take care of their land. But outside the ranch, no one owned the land. It was open to nomads and their herds. Though knowing nothing of Karl Marx, the herdsmen followed his famous advice of 1875: "... to each according to his needs." Their needs were uncontrolled and grew with the increase in the number of animals. But supply was governed by nature, decreasing drastically during the drought of the early seventies. The herds exceeded the natural "carrying capacity" of their environment, soil was compacted and eroded, and "weedy" plants, unfit for cattle consumption, replaced good plants. Many cattle died, and so did humans.原因很简单。
公地悲剧英语作文
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公地悲剧英语作文Life is a journey filled with endless possibilities and opportunities. Each day presents us with new challenges, new experiences, and new lessons to learn. As we navigate through this complex tapestry of existence, we often find ourselves searching for purpose, meaning, and a sense of direction. Yet in the midst of this quest, we may sometimes feel a profound sense of emptiness, a void that seems to defy explanation.This void, this None, is not a void of nothingness but rather a void of infinite potential. It is a space where the boundaries of our understanding blur, where the limits of our imagination are tested, and where the very essence of our being is called into question. It is a realm where the familiar and the foreign coexist, where the known and the unknown converge, and where the very foundations of our reality are called into question.In this space of None, we are confronted with the essential questions of our existence. Who are we? What is our purpose? What is the nature of reality itself? These questions, though seemingly simple, are in fact profoundly complex, and the answers they seek often elude us. Yet it is in this very search for answers that we find the truerichness and depth of the human experience.As we delve deeper into the realm of None, we begin to realize that the very act of questioning is a fundamental part of our existence. It is through this questioning, this constant exploration of the unknown, that we expand the boundaries of our knowledge and understanding. It is through this process that we come to appreciate the beauty and complexity of the world around us and the incredible tapestry of life that we are a part of.But the journey through None is not an easy one. It is fraught with uncertainty, fear, and the constant challenge of confronting our own limitations. We may find ourselves grappling with existential questions that seem to have no clear answers or struggling to make sense of the seemingly chaotic and unpredictable nature of the world. Yet it is precisely in these moments of uncertainty and challenge that we have the opportunity to grow, to evolve, and to discover the true depth and richness of our own being.As we navigate the realm of None, we may find ourselves encountering a wide range of emotions and experiences. We may feel a sense of wonder and awe at the vastness of the universe or a profound sense of humility in the face of the immensity of creation. We may also find ourselves confronted with feelings of fear, anxiety, and even despair as we grapple with the unknown and the uncertain.Yet it is in these moments of struggle and uncertainty that we have the opportunity to truly discover the depth and resilience of the human spirit. It is in these moments that we are called upon to dig deep within ourselves, to tap into the wellspring of our own inner strength and wisdom, and to find the courage to confront the challenges that lie before us.And as we do so, we may find that the very act of confronting the unknown, of embracing the void of None, can be a profoundly transformative experience. We may discover hidden reservoirs of strength and resilience within ourselves or uncover new perspectives and insights that challenge our preconceptions and expand our understanding of the world.Indeed, the journey through None is not one that can be undertaken lightly. It requires a deep commitment to self-reflection, a willingness to confront our own fears and limitations, and a profound sense of openness and curiosity. But it is a journey that holds the potential to unlock the deepest and most profound aspects of our humanity and to connect us to the vast and wondrous tapestry of existence that lies beyond the confines of our own individual experience.So let us embrace the void of None and let us embark on this journey of discovery and transformation. Let us be willing to confrontthe unknown, to question our assumptions, and to explore the depths of our own being. For it is only through this process of exploration and self-discovery that we can truly come to understand the true nature of our existence and the incredible potential that lies within each and every one of us.。
一次土地坍塌英语作文
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一次土地坍塌英语作文The ground suddenly collapsed, leaving a massive holein the middle of the field. It was a shocking sight, as if the earth had opened up to swallow everything in its path. The once solid ground now looked like a giant sinkhole, ready to devour anything that came too close.People gathered around the edge of the hole, staring in disbelief at the sheer size of the collapse. Some whispered about the dangers of such unexpected disasters, whileothers simply stood in silence, unable to comprehend the magnitude of what had just happened.Emergency services were quickly called to the scene, their sirens blaring as they rushed to assess the situation. It was a race against time to ensure that no one wastrapped or injured in the collapse, as the ground continued to crumble and shift unpredictably.As the dust settled and the chaos subsided, questionsbegan to arise about the cause of the collapse. Some blamed it on natural erosion, while others pointed fingers at human interference and neglect. The truth remained unclear, leaving a sense of unease lingering in the air.In the aftermath of the collapse, the community came together to support those affected by the disaster. Neighbors offered help and shelter to those displaced bythe collapse, showing the resilience and compassion thatcan emerge in times of crisis.Despite the destruction and loss caused by the collapse, there was also a sense of unity and solidarity that emerged from the chaos. It was a reminder that in the face of adversity, people can come together to overcome challenges and rebuild stronger than before.。
公地悲剧中文翻译
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公地的悲剧garrett hardin在一项关于核战争的文章末尾,Wiesner和York得出结论认为:“军备竞赛的任何一方,都面临着这样的两难境地,即稳步增加军事实力和不断下降的国家安全局面。
我们从专业的角度来看,认为这一难题没有技术解决方案。
如果大国继续在科学和技术领域寻求可能的解决方案,结果将是使局势恶化。
“我想请你们不要只是盯着文章的主题——(在核大战中的国家安全),而是看到文章触及到的更广阔的视角。
但在他们的结论里,没有任何技术可以解决这个问题。
但是在专业和次流行科学杂志上发表的文章以及有关的讨论来看,这个问题或许有一个技术解决方案。
一个技术解决方案可以被定义为一个只需要在自然科学的技术变革,以及要求极少甚至没有在人类的价值观或道德观念有所改变的方案。
在我们当前的时代里,(虽然不是在以前的时代)技术解决方案总是受欢迎的。
由于在以前的预言失败,因此我们需要勇气去断言理想的技术解决方案不是不可能。
Wiesner和York展出这种勇气。
他们在一份出版的杂志里边坚持认为,解决办法是不要在自然科学中找到。
他们谨慎的用短语来证明他们的观点,“这是我们的专业判断。
”无论及结论正确与否,那不是本文章的关注。
相反,这里关注的是与一类人有关的概念,可称为“技术上没有问题。
很明显这一类集合不是空集。
我们来回顾一类博弈,去考虑一下我怎么能赢得这次博弈?”众所周知,我不能,如果我假设(在遵守游戏规则时)我的对手对博弈的情形有完全信息。
换句话说,没有“技术解决”这一问题。
在给与“赢”这个词予一个激进的意义后,我能取得胜利。
”我可以打我对手的头,或者我可以伪造记录。
在某种意义上说,每次我赢的时候,根据我们直观的理解。
等同于放弃博弈。
(我当然还可以公开放弃博弈不玩。
这是大多数成年人的做法。
)这类“没有技术解决的问题”的集合其实有他的子集。
我的论点是,“人口问题,”作为传统设想,是这一类的子集。
想知道“它是如何在传统上设想的”则需要一些评论。
共地悲剧资料
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共地悲剧资料一.是什么1968年英国加勒特·哈丁教授(Garrett Hardin)在《The tragedy of the commons》一文中首先提出“公地悲剧”理论模型。
公地作为一项资源或财产有许多拥有者,他们中的每一个都有使用权,但没有权利阻止其他人使用,而每一个人都倾向于过度使用,从而造成资源的枯竭。
过度砍伐的森林、过度捕捞的渔业资源及污染严重的河流和空气,都是“公地悲剧”的典型例子。
之所以叫悲剧,是因为每个当事人都知道资源将由于过度使用而枯竭,但每个人对阻止事态的继续恶化都感到无能为力。
而且都抱着“及时捞一把”的心态加剧事态的恶化。
公共物品因产权难以界定而被竞争性地过度使用或侵占是必然的结果。
二.为什么说到哈丁的“公地悲剧”或曰“公有资源的灾难”,那是对个人在利用公共资源时存有私心的确证。
哈丁将这一状态模型化:一个向众人开放的牧场,在其中每个牧羊人的直接利益取决于他所放牧的牲畜数量的多少。
由于在缺乏约束的条件,当存在过度放牧问题时,每个牧羊人虽然明知公地会退化,但个人博弈的最优策略仍然只能是增加牲畜数量,久而久之,牧场可能彻底退化或废弃。
这就是“公地悲剧”。
“公地悲剧”的发生,人性的自私或不足只是一个必要的条件,而公产缺乏严格而有效的监管是另一个必要条件。
所以,“公地悲剧”并非绝对地不可避免。
三.怎么办1.明确和稳定产权尽可能地将资源或企业的所有权明晰,并制定相应的政策法规,明确责任和义务。
科斯定理证明,一旦产权明确规定,而各利益相关者之间的联络、谈判、签约等等的成本足够低,则无论将产权划归给谁,最终总能达到该资源的最优配置和使用。
同样道理,只有做好企业的产权安排,才能避免“公地悲剧”的发生。
对国有企业而言,应明确占有权、使用权、收益权和处置权。
必须指出的是,产权稳定和产权明确同等重要。
如果产权不稳定,即使产权明确,也会对资源进行掠夺性的使用。
2.配合企业制度改革基于具有公地特性的国有企业往往发生“悲剧”这样的现实,国有企业应退出竞争性领域,保持在非竞争性领域的地位。
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哈丁:公地的悲剧(The Tragedy of the Commons)时间: 2019-10-23,人气: 609J.B. Wiesner和H.F. York在一篇关于核子战争前景的发人深省文章结尾时说:「武器竞赛的双方都是…面对持续增强的军事力量和持续减弱的国家安全。
深思之下,我们的专业意见认为这困局没有技术性的解决办法。
如果大国只是在科学和科技这方面找寻解决办法,结果只会令情况恶化。
」希望各位不要集中注意文章的主题(核武世界的国家安全),而是要留意作者的结论,即是问题没有技术性的解决办法。
专业和半通俗科学期刊的评论,差不多都隐喻评论的问题是有技术性的解决办法。
技术性解决办法可以定义为只要改变自然科学的技术,无需或只是稍为改变人的道德价值或概念。
我们现在一般都欢迎有技术性解决办法(以前并非如此)。
因为以前的预言往往失准,要有莫大勇气才会断言没有预期的技术性解决办法。
Wiesner和York 表现出勇气,在科学期刊发表文章,坚持问题不能在自然科学找到解决办法。
他们小心翼翼为声明加上以下的批注:「深思之下,我们的专业意见…。
」本文所关注的。
不是他们是否正确,而是一个重要的观点:有一组关乎人的问题可以称为「没有技术性解决办法的问题」,或是更明确地说:认定和讨论这些问题是其中之一。
要表明这类问题不是空号很容易。
还记得划井游戏。
想一想:「我如何赢划井游戏?」假设(依照赛局理论的惯例)我的对手是个中能手,大家都知道我不可能赢。
换句话说,问题没有「技术性解决办法」。
要赢,我只能把「赢」的意义根本改掉。
我可以打对方的头,可以弄虚作假。
每一种我要「赢」的方法,都是某种意义上放弃了我们认知了解的游戏。
(我当然可以公开放弃—不玩。
大多数成年人都这样。
)「没有技术性解决办法的问题」有其它的命题。
我的论题:大家惯常认知的「人口问题」是这样的命题。
要说明一下大家是怎样惯常认知的。
持平的说,大多数人为人口问题苦恼,要找出方法避免人口过多的邪恶,但不放弃他们正在享受的特权。
他们以为海洋养殖或发明小麦新品种会解决问题—从技术方面。
我尝试证明他们不能找到解决办法。
人口问题正如要赢划井游戏,不能技术性解决。
我们要最大化什么?如马尔萨斯所言,人口自然地以「几何级数」增加,或是我们现在的说法是函数增加。
在一个有限的世界,这即是说世界物品的人均份额必然减少。
我们的世界是否有限?一个中肯的抗辩说法:世界是无限的,或是我们不知道世界不是无限。
但是,从实际问题角度来看以后几代人和可见的科技,很清楚如果我们不是实时假设陆上人类可用的世界是有限的,我们会大大增加人类的痛苦。
「太空」不是逃生门。
有限的世界只能养活有限的人口;因此到了最后,人口增长必然是零。
(零增长的永恒大幅度上下波动是无关宏旨的变动,不在此讨论。
)当条件符合,人类的情况会是怎样?明确地说,边泌的目标:「最大数目的最大好处」能否实现?不可能—理由有二,单是一个已足够。
第一个理由是理论性。
数学上,两个函数是不可能同时最大化。
Neumann和Morgenstern已经清楚说明,其中的绝对原理是起码可以追溯至D'Alembert (1717-1783) 的偏微分方程式。
第二个理由是直接源于生物事实。
任何生物要生存,必须有一个能源来源(例如食物)。
能源用于两个目的:维生和工作。
人要维持生命,每天需要1600 千卡路里(维生卡路里)。
维生以外所做的一切可以定义为工作,由摄取的「工作卡路里」支持。
工作卡路里不是只用于我们日常谈到的工作;所有享乐形式都需要:游泳、赛车、音乐,吟诗。
如果我们的目标是人口最大化,我们要做什么是很明显。
我们要每个人的工作卡路里最接近零。
没有可口美食,没有渡假,没有运动,没有音乐,没有文学,没有艺术…我以为无需争议或实证,大家都同意人口最大化不会物品最大化。
边泌的目标是不可能的。
我在达成以上的结论时,作出一贯的假定,问题就是取得能源。
有了核能,有些人会质疑这假定。
但是,即使有无穷能源,人口增长依然带来不可逃避的问题。
正如J. H. Fremlin机智表达,取得能源的问题,被能源消散取而代之。
分析的算术符号正负倒转;但边泌的目标是不能达到。
因此,最合适的人口是少于最大。
定义最合适的困难大;依我所知,没有人曾郑重处理这问题。
要达致一个可接受和稳定的解决办法,需要多过一代人的辛勤分析—和更大说服力。
我们期望每个人有最大好处;但什么是「好处」?某人的好处是荒原,另一人是大众的滑雪小屋。
某人的好处是河口盛产水鸭,供猎人射击;另一人是工厂用地。
我们一般说比较各人的心头好是不可能的,因为物品是不配比较。
不配比较就是不能比较。
理论上这可能是对的;但实际生活中不配比较是可以衡量的。
只需要一套判断的标准和比重的制度。
大自然的标准就是生存。
何等物种较好:小而可掩藏,或是大而有劲力?物竞天择会比较不配比较的。
达致的妥协是视乎大自然为众多变量的价值作出比重。
人必须模仿这过程。
无可置疑地,他事实上不自觉地已是如此。
只有当隐藏的决定表面化时才有争端。
未来的工作难题是要作出一个可接受的比重理论。
这项智力难题因协同作用,非线性变化,和考虑将来而变得困难,但(原则上)不是不可能解决。
至今,是否有任何文化组群解决了这实际问题,即使是直觉层面?一个简单事实证明还没有:现今世界没有繁荣人口在一段时期内达致零增长。
只要任何人在直觉上认定最佳点,就可以很快达到,之后增长率为零,其后亦保持为零。
当然,增长率为正数,可以作为人口在最佳点之下的证据。
但是,以任何理性标准来看,今天世上增长最快的人口,(一般而言)是最悲惨的。
这种连系(无须是一成不变的)令人对所谓正数增长率表示人口还没有达致最佳点的乐观假定感到怀疑。
迈向人口最佳数目,我们要驱逐亚当?史密的实践人口学的幽灵,才可以取得寸进。
「国富论」(1776) 广为宣扬「无形之手」,这概念即是个人「只是追求自己的利益」,因而「被无形的手指挥,推动…公众利益。
」亚当?史密没有宣称这是一成不变的真理,甚至他的追随者也没有。
但他带动的主导思想趋势自此干扰着基于理性分析的积极性行动。
这种趋势就是假定个人决定事实上是整个社会的最佳决定。
如果这假定是正确的,现在的自由放任生育政策是有据可依。
如果这假定是错误的,我们重新检视种种个人自由,看看那些是可以辩护的。
公地自由的悲剧无形之手控制人口的反驳论点,最先见诸1833年一位业余数学家William Forster Lloyd (1794-1852) 撰写的一本鲜为人知的小册子,可称之为「公地悲剧」;「悲剧」一词借用自哲学家Whitehead:「戏剧性的悲剧要素不是不快乐,而是蕴藏于事物无懊无悔运作的严肃性。
」他续后又说:「命运之无可避免,只能以人生不如意事引证,只有这样戏剧才可显现逃避是徒然的。
」公地悲剧是如此发展的。
想象草原对大众开放,估计每个牛郎都会在公地饲养最多的牛只。
数百年来,这样的安排都是相安无事,因为部族战争,偷猎,和疾病把人和动物的数目保持在土地承载能力之下。
最终,人们长久渴望的社会稳定的一天到来,是醒悟的时候了。
这时,公地的内在逻辑无情地导致悲剧。
作为理性人,每名牛郎追求取得最大得益。
或明或暗,有意无意,牛郎抚心自问:「牛群多添一头,对我有什么效益?」这效应有正、负成份各一。
(1)多一头动物的函数是正成份。
出售牛只的收益全归牛郎,所以正效益接近+1。
(2)负数部份是多一头动物造成的过度放牧的函数。
因为过度放牧的效果由全体牛郎承担,所以任何一位牛郎作出决定,负效益只是-1的小部份。
把这些效益成份相加,理性牛郎总结他只有一个理性选择:多养一头牛。
再多养一头…但这也是分享公地的每一位牛郎的结论。
悲剧因此而起。
每个人都是被制度束缚,驱使他无限制地增加牛只—而世界是有限的。
在一个信奉公地自由的社会中,每个人都追求本人的最好利益,而整体是走向毁灭的终点。
公地自由带来整体毁灭。
有人会认为这是陈腔滥调。
这不是码?某程度上来说,我们几千年前就学会了,但物竞天择偏向于心理否认。
纵使个人也是成员的社会受损,个人会因为取得私利而否认真相。
教育可以对衡做错事的自然倾向,但必须持续才可以对抗一代传一代的无情力。
几年前,在麻省市有一件小事足以说明知识逐渐消失。
圣诞节购物期间,市中心的停车表用胶袋遮掩,上有告示:「圣诞节后重开。
免费停车由市长和市议会提供。
」换句话说,面对本来已是短缺的停车位的需求增加,城市之父再建立公地制度。
(嘲笑一句,我们怀疑他们这倒退的行为是得(选票)大于失。
)大概是同样道理,我们长久以来已明白公地的逻辑,可能是自从发现农业或发明私人房地产的产权。
但了解的大都是特殊个案,不足以一般而论。
即使到了现在,租用西部山区国家土地的牧人证实这样矛盾的了解;他们向联邦机关施压,要求增加牛只数目,几乎因为过度放牧导致侵蚀和杂草丛生。
全球海洋依然因为公地哲理残存而受害。
海洋国家依然听从「四海自由」的口令。
他们声言相信「海洋有无穷资源」,令多种鱼类和鲸鱼几乎灭绝。
国家公园是公地悲剧的另一个例子。
现今是对外开放,没有限制。
公园范围是有限的—只有一个优胜美谷—但人口增长没有限制。
公园访客享乐的价值逐渐减弱。
很简单,我们要尽快不要把公园当作公地,否则对任何人都不会有价值。
我们可以做什么?有几个方案。
可以出售为私人产业;可以保留为公共财产,但分配进入的权利。
分配可以是以财富为基础,用拍卖方式。
亦可以根据一些彼此同意的标准来定优劣。
可以是彩票。
或是先到先得,由人龙决定。
我以为以上提到的都令人反感。
但我们必须选择—或是默许我们称为国家公园的公地被毁。
污染污染公地悲剧的反面是污染问题,不是从公地拿走,而是放入—往水中排放污水,或化学、放射性、和热力废物;往空气排放有害和危害的气体;在视线所及树立令人分神和不悦目的广告。
计算效益和前述一样。
理性人发觉他向公地排放废物的成本,是少于排放前洁净废物的成本。
无个人都是一样;只要我们这些独立,理性,自由的投机者自作妄为,大家都受缚于「自家弄脏自家」的制度。
食物篮子的公地悲剧,因为私产或类似的正式安排而避免了。
但我们周围的空气和水不能轻易地分隔,所以要用不同的方法防止污水坑公地悲剧:强制的法律或税务措施,做成污染者在排放前处理污染物成本比不处理为低。
我们解决这问题的进展,不如解决第一个问题。
停止我们耗尽地球的直接资源的私产概念,实际上助长污染。
小河岸边工厂的主人—他的产权伸延到小河的中央—不容易明白弄脏流经门前的河水不是他的自然权利。
法律永远赶不上时代,需要修修补补来适应这「公地」的新意识。
污染问题是人口的后果。
未开发地区的孤独居民如何弃置废物,没有所谓。
祖父以前常说:「水流十里,自我净化。
」当他是小孩时,这神话可能近乎真理,因为没有太多人。
但人口变得密集,大自然的化学和生物循环过程负荷过重,呼唤产权要重新定义。