Would You Pull the Trolley Switch? Does it Matter? - The Atlantic

This haunting choice is a variation of the “trolley problem,” an iconic philosophical thought experiment. (If you've never heard of it ... SkiptocontentSiteNavigationTheAtlanticPopularLatestSectionsPoliticsIdeasFictionTechnologySciencePhotoBusinessCulturePlanetGlobalBooksPodcastsHealthEducationProjectsAmericaInPersonFamilyEventsShadowlandProgressNewslettersTheAtlanticCrosswordPlayCrosswordThePrintEditionLatestIssuePastIssuesGiveaGiftSearchTheAtlanticQuickLinksDearTherapistCrosswordPuzzleManageSubscriptionPopularLatestSignInSubscribeArunawaystreetcarishurtlingtowardsfiveunsuspectingworkers.Doyoupullaswitchtodivertthetrolleyontoanothertrack,whereonlyonemanworksalone?Ordoyoudonothing?Thishauntingchoiceisavariationofthe“trolleyproblem,”aniconicphilosophicalthoughtexperiment.(Ifyou’veneverheardofitbefore,trythis.)Puzzling,ridiculous,andoddlyirresistible,thisimaginaryscenariohasprofoundlyshapedourunderstandingofrightandwrong.Inthepast40yearsithasoccupiedtheattentionofbrilliantminds,fromacademicethiciststomoralpsychologiststoengineers.Ithashelpedthemtrytoanswerprofoundquestions—howdoweact,andhowshouldwe?Butinitsfifthdecade,isthetrolleyproblemstartingtoshowitsage?ThoughtexperimentshavebeenessentialinscholarlydiscoursesincetheancientGreeksandRomans.Mostremainsecludedintheivorytower,whileahandful,likethesimultaneously-dead-and-aliveSchrödinger’scatorthePrisoner’sDilemma,escapetherealmoftheacademictobecomepowerfulculturalmainstays—notalwaysforwell-understoodreasons.Curiously,thefirstthinkerstopopularizeandanalyzethetrolleyproblemwerewomen—ingeneral,rarevoicesinphilosophy.Itsstorybeginsin1967atOxfordUniversity,whenthe“granddameofphilosophy”PhilippaFootdevisedtheexampleoftherunawaystreetcar—“tram”inEngland,“trolley”intheU.S.—whilediscussingthepermissibilityofabortion.Afewyearslater,JudithThomson,aphilosopherattheMassachusettsInstituteofTechnology, coinedtheterm“trolleyproblem”andcreatedwhatwouldbecomeitstwomostfamousvariants,the“footbridge”andthe“switch.”Inthe“footbridge”scenario(alsoknownas“fatman”),thestreetcarisheadingtowardsfiveworkers,butthistimeyou’reonafootbridgeoverthetrack.Standingprecariouslyclosetotheedgeofthebridgenexttoyouisaverylargeman,who,ifhehappenedtotoppleontothetrackbelow,couldstopthetrolleybeforeitreachesthefive.Doyoupushhim?Thomson’swritingsparkedsomuchinterestinthephilosophicalcommunitythatasub-disciplineof“trolleyology”emergedduringthe‘70sand‘80s.Thetrolleydilemmasvividlydistilledthedistinctionbetweentwodifferentconceptsofmorality:thatweshouldchoosetheactionwiththebestoverallconsequences(inphilosophy-speak,utilitarianismisthemostwell-knownexampleofthis),likeonlyonepersondyinginsteadoffive,andtheideathatweshouldalwaysadheretostrictduties,like“neverkillahumanbeing.”Thesubtledifferencesbetweenthescenariosprovidedhelpedtoarticulateinfluentialconcepts,likethedistinctionbetweenactivelykillingsomeoneversuspassivelylettingthemdie,thatcontinuetoinformcontemporarydebatesinlawandpublicpolicy.Thetrolleyproblemhasalsobeen,andcontinuestobe,acompellingteachingtoolwithinphilosophy.Mostofusprobablywon’tfindourselvesinastrangelybarelandscape,coincidentallyplacednexttoalife-givingswitch.Bythelate‘90s,trolleyproblemshadfallenoutoffashion.Manyphilosophersquestionedthevalueoftheconclusionsreachedbyanalyzingasituationsobizarreandspecific.Itwasn’tcleartrolleyscouldeverfindalifeoutofthepagesofacademicjournalsuntilonephilosophygraduatestudent,JoshuaGreene,revivedthemwiththemoderntechniquesofneuroscience.GreenedecidedtoslidepeopleintoanfMRImachinetoglimpsewhathappenedintheirbrainswhenfacedwithdifferenttrolley-problemscenarios.Heultimatelyfoundthattheanswerspeoplegavecorrelatedwithhowemotionallyengagedtheyfeltwiththedilemma.Thedecisiontopulltheswitchwasrelatedtoactivityintheprefrontalcortex(associatedwithcool,consciousdeliberation),whilethedecisionnottopushthefatmaninvolvedareasliketheamygdala,associatedwithstrongemotionalreactivity.Thepaperthatreportedtheseresultsin2001inspiredhundredsmorestudiesusingthetrolleyproblemtostudymoraldecision-making—andalsopiquedinterestfrompeopleinotherfields,likesociologists,economists,andanthropologists.Greeneandothershaveusedtrolleystoconcludethatstrongmentalimageryandvisceralemotionsmakeusmorelikelytomakeanintuitivedecision(“neverkillahumanbeing”),asopposedtoamoremathematicalcalculateddecision(fivelivesversusone).Greene’sresearchalsosuggeststhatthereasonpeoplearelesslikelytopushthefatmanthantoflipaswitchisbecauseweallpossessabiologicallypre-programmedemotionalaversiontodeliveringharmpersonally(touchingamanasyoushovehimoffabridge)asopposedtoimpersonally(yankingalever).RecommendedReadingIsOneoftheMostPopularPsychologyExperimentsWorthless?OlgaKhazanTheHypocrisyofProfessionalEthicistsEmmaGreenTheEthicsofAutonomousCarsPatrickLinTheethicistPeterSingercitesGreene'sresearchtosupportsomeofhispositionsaboutwhyweoughttomakegreatersacrificesforproblemsthatmayseemdistant,likeworldpovertyoradiseaseraginghalfwayaroundtheglobe.Singerarguesthatweshouldn’tavoidourmoralobligationstosomeonejustbecausetheylivetoofarawaytoengageourbrain’semotionalmachinery.DespitetheinsightsSingerandothersgainedfromthetrolleyproblem,manypsychologists,likephilosophersbeforethem,eventuallybegantotireofit.TheUniversityofCalifornia,Irvine,psychologistChristopherBaumanandhiscolleaguessummarizedtheprobleminapaperlastyear:Researchershavenotedthattrolley-problemscenariosfrequentlycausestudyparticipantstolaugh,meaningtheyaren'ttakingtheexperimentseriously—possiblybecausethescenariosdon'tmirrorbelievable,real-lifemoraldilemmas.Mostofusprobablywon’tfindourselvesinastrangelybarelandscape,coincidentallyplacednexttoalife-givingswitch,orforcedtodecidewhetherornottopushamanoffabridge.Butrecently,trolleyproblemshavefoundnewlifeinamorerealisticapplication:researchondriverlesscars.Whenavehiclehasnooptionbuttohaveacollision,whichcollisionisitgoingtohave?ChrisGerdes,aprofessorofmechanicalengineeringatStanfordandthedirectoroftheirautomotive-researchcenter,hasspentyearsonalgorithmsforautomatedvehicles,figuringouthowthesecarsshouldhandleemergenciesandmakedecisionsacceptabletosociety.WhenIspoketoGerdes,hehadjustreturnedfromatestdriveontheCaliforniastreets.Heexplainedthatmanyofthesituationsdriverlesscarswillfaceinvolveconflictingpriorities.Whenavehiclehasnooptionbuttohaveacollision,whichcollisionisitgoingtohave?Thisiswheretrolleyscomein.“Theseproblemsweweretryingtosolvewerenotsimplytechnicalissues,butthingsthatyoucouldactuallyturntophilosophyforsomeinsight,”Gerdestoldme.“Inthosecaseswherelossoflifemaybeinevitable—andtherewillbesituationslikethat—wewantthecartomakeareasonabledecision.”Gerdesalsothinksthetrolleyproblemisausefulspringboard:“[It]isonewayofhighlightingthefactthatyoueventuallyreachapointwhereyouhavetomakesomedecisions,andnoteverybodywillagree.”Gerdeshasbeenworkingwithaphilosophyprofessor,PatrickLin,tomakeethicalthinkingakeypartofhisteam’sdesignprocess.Lin,whoteachesatCalPoly,spentayearworkinginGerdes’slabandhasgiventalkstoGoogle,Tesla,andothersabouttheethicsofautomatingcars.Thetrolleyproblemisusuallyoneofthefirstexamplesheusestoshowthatnotallquestionscanbesolvedsimplythroughdevelopingmoresophisticatedengineering.“Notalotofengineersappreciateorgrasptheproblemofprogrammingacarethically,asopposedtoprogrammingittostrictlyobeythelaw,”Linsaid.Butthetrolleyproblemcanbeadouble-edgedsword,Linsays.Ontheonehand,it’sagreatentrypointandteachingtoolforengineerswithnobackgroundinethics.Ontheotherhand,itsprevalence,whimsicaltone,andiconicstatuscanshieldyoufromconsideringawiderrangeofdilemmasandethicalconsiderations.Linhasfoundthatdeliveringthetrolleyprobleminitsoriginalform—streetcarhurtlingtowardsworkersinastrangelybarelandscape—canbecounterproductive,soheoftenre-formulatesitintermsofautonomouscars:You’redrivinganautonomouscarinmanualmode—you’reinattentiveandsuddenlyareheadingtowardsfivepeopleatafarmer’smarket.Yourcarsensesthisincomingcollision,andhastodecidehowtoreact.Iftheonlyoptionistojerktotheright,andhitonepersoninsteadofremainingonitscoursetowardsthefive,whatshoulditdo?Itmaybefortuitousthatthetrolleyproblemhastrickledintotheworldofdriverlesscars:Itilluminatessomeoftheprofoundethical—andlegal—challengeswewillfaceaheadwithrobots.Ashumanagentsarereplacedbyroboticones,manyofourdecisionswillceasetobein-the-moment,knee-jerkreactions.Instead,wewillhavetheabilitytopremeditatedifferentoptionsasweprogramhowourmachineswillact.ForphilosopherslikeLin,thisistheperfectexampleofwheretheorycollideswiththerealworld—andthoughtexperimentslikethetrolleyproblem,thoughtheymaybeabstractoroutdated,canhelpustorigorouslythinkthroughscenariosbeforetheyhappen.LinandGerdeshostedaconferenceaboutethicsandself-drivingcarslastmonth,andhopetheresultingdiscussionswillspreadouttoothercompaniesandlabsdevelopingthesetechnologies.“Basicresearchintomoralityisanimportantpartofthehumancondition.”Butcouldtrolleyproblems,beyondhelpingustodesigntechnology,alsoserveasatoolforeverydayself-improvement?ThephilosopherandpsychologistEricSchwitzgebel,whohasstudiedthebehaviorofethicsprofessors,foundthatphilosophicalexpertisedoeslittletochangetheirmoralbehavior—forexample,they’renomorelikelythanothersofsimilarsocialbackgroundtodonatetocharityorstopeatingmeat.Schwitzgebeldoubtsthatspendingtimepuzzlingovertrolleyscanactuallyhelpapersonmakebettermoraldecisions.Buthestillthinksit’susefultoholdontothoughtexerciseslikethetrolleyforresearchpurposes,eveniftheydon’treallyseemtochangethewaypeoplebehaveintherealworld,orareanimperfectanaloguetothemessydecisionstheytypicallyface.“Weaspsychologistsandexperimentalphilosophersshouldbeprettycarefulabouthowsubjectsareinterpreting[thetrolleyproblem],”Schwitzgebeltoldme,“andthereisacertainlackofexternalvaliditytoit.Ontheotherhand,it’sanice,cleanproblem.”Thissimplicity,Schwitzgebelbelieves,iswhatmakesitsuchanincisivetoolforscientificinvestigation.Scientistsstillneedthetrolleyproblem,inadditiontomorerealisticscenarios,hesaid,because“basicresearchintomoralityisanimportantpartofthehumancondition.”It’shardtotellifthismeansthetrolleyproblemwillmakeanotherresurgence,thoughJudithThomsonherselfwrotetomeinanemail:“Idon’tforamomentthinkthetrolleyproblemisapproachingitsend.”Asfortherestofus,whomaybewearyfromwonderingwhywecouldn’tjustwarntheworkerstogetoutofthewayandavoidthewholemessinthefirstplace,myadviceisthis:Justkeepsippingyourlatte.