搜索
Canthemajorproblemsofcitiesbesolved?XiangYanAcity,asdescribedbyLewisMumford,“isageographicplexus,aneconomicorganization,aninstitutionalprocess,atheaterofsocialaction,andanestheticsymbolofcollectiveunity.”(Mumford,1937)Assuchcomplexsystems,citiesarediversefromeachotherduetotheirdistinctgeographical,economic,political,social,cultural,andestheticcharacteristics.Therefore,itiscommonlyacceptedthateverycityisuniqueandproblemsofeachcityshouldbedealtwithseparately.Infact,manyplannersbelievethateachproblem,eveniftheyareofthesamecityoreventhesameplace,isessentiallyuniqueas“foranytwoproblemsatleastonedistinguishingpropertycouldbefound.”(Rittel&Webber,1973)Nevertheless,therearescientists,namely,BettencourtandWest,showingtherearesomesimplemathematicallawsaboutcitygrowthandambitiouslyproposingaunifiedtheoryofurbanliving.1.Examiningthe“unifiedtheoryofurbanliving”AccordingtotheresearchofBettencourtandWest,thesizeofpopulationismajordeterminantofmostcharacteristicsofacity(Bettencourt&West,2010).Theirworkshowsdoublingthepopulationofanycityrequiresonlyan85%increaseinresources,andalso,resultsina15%increaseinallpercapitasocio-economicquantities.Afteracitydoublesinsize,however,negativemetricssuchascrime,trafficcongestionandincidenceofcertaindiseasealsoincreaseby15%(Bettencourt&West,2010).Theseresults,showingthesimilarpatternsinWest’sbiologicalfindingsthatmathematicalequationscouldbedevisedtoshowthevitalfactsaboutanimals—heartrate,size,caloricneeds—areinterrelated(Lehrer,2010),leadthisformerphysicstoconfidentlyassertthatthedynamics,growthandorganizationofcitiescouldbesimplyunderstoodthroughmathematicallaws,andthus“a‘grandunifiedtheoryofsustainability’withcitiesandurbanizationatitscorecouldbedeveloped.”(Bettencourt&West,2010)Nevertheless,isthisreallyleadingustoanunifiedurbangrowththeory,andcanthecitiesbeunderstoodwiththesesimplemathematicalequations?Probablynot.Firstofall,thegeneralizationofthe“15percentlaw”isstillarguable.Richardson,inhisbookTheEconomicsofUrbanSizesummarizedtheargumentsrelatingtocitysize,andrevealedthatthecostsandbenefitsofincreasingthecitysizevariedwiththeconfigurationofthecityanditsspatialrelationshipwithothercities,andinparticularwiththeeconomicstructureofthecity(Richardson,1973).Forexample,ratherthan15%,Segal(1976)foundthat“agglomerationeffect”madeunitsoflaborandcapital8%moreproductiveinthelargestcities(Segal,1976).Thatistosay,cities,withtheirrespectivelyuniquespatialpatternsandeconomicstructures,aremostlikelytofollowdiversegrowthpatterns,whichasaresultunderminesthevalidityofaunifiedurbangrowththeory.However,itshouldbenotedthatmostexistingstudiesconfirmthatwiththesizeofacityincreaseitgainsboththepositiveandnegativeeffectsofagglomeration,buttheextentsofwhichvaryacrossstudies(Richardson,1973).Regardlessofthenumericexactnessofthemathematicalequations,anotherquestionistowhatextentthesescalinglawscouldhelpus“solve”thecities.IsitasWestassertsinbiologythat“[if]youtellmethesizeofamammal,Icantellyouatthe90percentleveleverythingaboutitintermsofitsphysiology,lifehistory,etc.”(West,2011)?Mostplannerswouldnotagreewiththat.Thefirstprobleminvolvestheeffectivenessofestimate(orprediction).Planningis“aprocessofpreparingasetofdecisionsforactioninthefuture,”(Dror,1963)andthusplannersaremakingpredictionsallthetime,yetanyexperiencedplannerwouldconfessnoguaranteecouldbeassertedtothesepredictions.Itisnotthatplannersarenotconfidentwiththeirwork,butthatfutureisneverpredictableasanychangefromfactorsinvolvingeconomic,political,social,cultural,technologicalorenvironmentalcouldmakeadifference.Thus,strivingforaccuracy,plannershavedevelopedthescenarioplanningapproachtoaccountforallthealternativepossibilities.AsinglevalueofurbanvariablesestimatedbythemathematicalequationsofWestisthereforeextremelyvulnerable.Soasanyotherestimatemadebymathematicalmodels,Westlimitshispredictionatapproximately85percentaccuracy(Lehrer,2010),whichmeansinrealitytheestimateofvariablesisarangeratherthanasinglevalue.Yet85percentaccuracymayseemveryhighthough,itisactuallysoroughthatindicatesfew—ifnotnoatall—implications.Thereasonisbecausecitiesnormallyinvolvemillionsofpeople,aslightdeviationcouldmeanalot.Forexample,onepercentagevarianceofGDPinacitywithapopulationofonemillioncouldmeanthousandsofjobsdifference.Anotherproblemisthatevenassumingtheestimateofurbanvariablesis100percentaccurate,thesepredictedmetricscouldofferfewinsightstounderstandcitiesandtosolvetheirproblems.Citiesaregargantuancomplexsystemsconsistofvariousgroupsofindividualswithdiverseinterests,valuesandnorms,andintheabsentofanoverridingsocialethicorsocialgoodnesstheirproblemsaredesperatelydifficulttodealwith.RittelandWebber(1973)termedplanningproblemsas“wicked”problemsduetotheirill-definedandelusivenatureincontrastto“tame”onesscientistsandengineersarefacing.Thesewickedproblemsrequirepainstakingeffortstowardssocialissuessuchasbalancingefficiencyandequity,henceestimatingurbanvariablesfromsomemathematicalequationsdevoidofanysocialmeaningbarelyconstitutesapreliminarystep.2.Thepredictableandunpredictablenatureoft