WhatisHacking'sArgumentforEntityRealism?

(ForthcominginSynthese)

BoazMiller

Abstract According to Ian Hacking’s Entity Realism, unobservable entities that scientists carefully

manipulate to studyotherphenomena are real.AlthoughHackingpresentshis case in an intuitive,

attractive, and persuasive way, his argument remains elusive. I present five possible readings of

Hacking’sargument:ano‐miracleargument,anindispensabilityargument,atranscendentalargument,

aVichianargument,andanon‐argument.IelucidateHacking’sargumentaccordingtoeachreading,

andreviewtheirstrengths,theirweaknesses,andtheircompatibilitywitheachother.

Keywords Scientific Realism; Entity Realism; Inference to the Best Explanation; Transcendental

Arguments;IndispensabilityArguments;Scepticism

1. Introduction

IanHacking’sEntityRealism(ER) isan influentialpositionwithin theScientificRealism(SR)

debate.AccordingtoER,unobservableentitiesthatscientistscarefullymanipulatetostudyother

phenomena, such as electrons that physicists spray froman electron gun, are real. Although

Hackingpresentshiscaseinanintuitive,attractive,andpersuasiveway,hisargumentforER

remains elusive. I suggest five interpretations of Hacking’s argument for ER: a no‐miracle

argument(NMA),anindispensabilityargument,atranscendentalargument,aVichianargument,

andanon‐argument.1Idrawthedistinctionsbetweenthesedifferentkindsofargumentbased

onthedifferentepistemicwarrantstheysupposedlyenjoy.

Withinthispaper,Iamlessinterestedinthequestionofwhichreadingmostaccurately

capturesHacking’sintentions,andmorewiththequestionofwhichreadingbestsupportsER.

ButIacknowledgethatanyanswertothelattershouldbetruetotheformer’sspirit.Thenext

B.Miller()

TheSidneyM.EdelsteinCenterforHistoryandPhilosophyofScience,TechnologyandMedicine,TheHebrewUniversityofJerusalem,9190401,Israel.

TheGraduatePrograminSTS,BarIlanUniversity,RamatGan,Israel,5290002.

e‐mail:boaz.miller@gmail.com

1ERisassociatedwithotherscholarsaswell(Cartwright1983;Giere1988).ThispaperisdevotedsolelytoHacking.

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sectionreviewsSRandsituatesERwithinit.Thesubsequentsectionsrespectivelydiscussthe

fivedifferent interpretations, and the last sectionexamines theextent towhich thedifferent

argumentscanworktogethermakingarobustcaseforER.

2. ERwithinSR

Roughly, SR states that science aims at discovering the truth about nature, and succeeds in

attaining this aim.Amoreprecise characterizationof SR is as a conjunctionof three theses,

dividedintosixsub‐theses:

Metaphysical:

(M1) Thereexistsamind‐independentworld.

(M2) Thisworldhasauniquestructure.

Semantic:

(S1) Scientific claims, particularly about unobservables, should be taken at

their face value; namely, they should be interpreted as purporting to

literallydescribethefurnitureofamind‐independentworld.

(S2) Whetherscientificclaimsaretrueorfalseisdeterminedbytheactualstate

ofaffairsintheworld,independentlyofourabilitytotestofverifyit;

Epistemic:

(E1) Theaimofscienceisattainingthetruthaboutnature,particularlyabout

theunobservableworld.

(E2) Matureempiricallysuccessfulscientifictheoriesachievethisaim,orcome

close to achieving it; namely, mature empirically successful scientific

theoriesaretrueorapproximatelytrueoftheirintendeddomains.2

Differentscholarsparsethesesub‐thesesslightlydifferently,butthisthreefolddivision

isnowstandard(Chakravartty2013).Someclarificationsandcontrastsareinorder.Someofthe

subthesescontrastSRwithcommitmentsofantirealistpositions.(M1)iscontrastedwiththe

2Mysubsequentmentionsoftruthshouldbeunderstoodasreferringtoapproximatetruthaswell.

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idealistdenialoftheexistenceofanexternalworld,andwithKantianperspectivism,whichholds

thatexperiencedrealityisinescapablymediatedbyhumancognition.(M2)rejectsnominalism,

which denies a natural grouping of the world into essences or kinds. (S1) rejects logical

empiricists’ and classic instrumentalists’ view that observable termsaremere shorthand for

describingobservablephenomena.(S2)statesanon‐epistemictheoryoftruth.Itiscontrasted

inter alia with verificationism, which states that the truth value of claims depends on their

verificationmethod.Forsatisfying(S2),realiststypicallyadheretoacorrespondencetheoryof

truth,accordingtowhichclaimsaretrueiftheycorrespondtotheactualstateofaffairsinthe

world,andfalseotherwise.SRiscommittedtosomeformofcorrespondencebetweenscientific

claimsaboutunobservablesandreality,butsomerealistssubscribetoadeflationaryaccountof

truth, and shoulder the burden of correspondence in other places, such as one’s theory of

reference,oratheoryoftruth‐making.3(E1)iscontrastedwithconstructiveempiricists’view

that the aim of science is empirical adequacy, i.e., attaining the truth only about observable

phenomena, and with classic instrumentalists, who posit merely providing useful tools for

predictionandcontrolastheaimofscience.(E2)expressesepistemicoptimismaboutscience

meetingitsaim.Notallscientificrealistsacceptalltheabovesubtheses.Thus,therearemany

possiblepartlyrealistpositions,becausethenumberofpossiblecombinationsthatacceptonly

someofthesesubthesesislarge.

AstrongargumentforSRisNMA.ItsmostfamousformulationisbyPutnam(1975,73):

“Thepositiveargumentforrealismisthatitistheonlyphilosophythatdoesn’tmakethesuccess

of science amiracle”. NMA ties together empirical success, reference of theoretical terms to

unobservableentities,andtruth.NMAisaninferencetothebestexplanation(IBE).Underthe

IBE model, we legitimately infer the truth of our best explanation of some given facts.

Explanatorymerits such as simplicity and scopedeterminewhich explanations are thebest.

Explanatory considerations determine plausibility, so the best explanation is the likeliest

3IthankAnjanChakravarttyandananonymousreviewerforthisclarification.

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explanation (Lipton 2004). NMA states that there are only two possible types of putative

explanationsfortheempiricalsuccessofscience:explanationsthatappealtothetruthofscience,

ormiraculousexplanations.Becauseputativeexplanationsthatappealtothetruthofscienceis

deemedasuperiorexplanationtoamiracle,welegitimatelyinfertheirtruth.

AnantirealistargumentagainstNMAisthepessimisticinduction(PI),whichchallenges

therelationsbetweensuccess,reference,andtruth.Laudan(1981)givesalonglistoftheories

from the history of science which were empirically successful yet false and contained non‐

referringterms.OnewaytoconstructLaudan’sPIisasanenumerativeinduction:

(PI0) Sinceallpastempiricallysuccessfulscientific theoriesare false, it is likely that

presentempiricallysuccessfultheoriesarealsofalse.

Anarguablybetterwaytoconstructtheargument(Lehoux2012,207)isasareductioofNMA:

(PI1) IfNMAisright,thenverynearlyallempiricallysuccessfultheorieswillbetrue.

(PI2) Butwehavealonglistoffalsesuccessfultheories.

(PI3) Therefore,NMAisfalse.

A common realist response to PI is selective scepticism, i.e., drawing a principled

distinctionbetweenthetrue,belief‐worthyelementsofempiricallysuccessfultheories,which

tendtobepreservedfromoldtonewtheories,andthefalse,belief‐unworthyelements,which

tendtobediscarded.AsChakravartty(2007,29)putsthis:

As in life generally, so too in science: do not believe everything you are told. Not allaspectsofscientifictheoriesaretobebelieved.Theoriescanbeinterpretedasmakingmanyclaimsaboutthenatureofreality,butatbestonehasgoodgrounds,orepistemicwarrant,forbelievingsomeoftheseclaims.Onlysomeaspectsoftheoriesarelikelytoberetainedasthesciencesmarchon.

Selectivescepticismcomesinmanyflavours.AnotableexampleisKitcher’s(1993,149)

distinctionbetweenatheory’sworkingposits,whichemploytheoreticaltermsthatrefertoreal

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unobservableentities,andpresuppositionalposits,whichdonot.Variousversionsofstructural

realismalsotrytodistinguishbetweenthetrueelementsofmaturetheories,andalltherest.

ERenters thepicturehere, asan influential versionof selective scepticism.Hacking’s

(1983,Ch.16)ERmakestwodistinctions:betweentheoriesandentities,andbetweentwokinds

ofunobservableentities:experimentalentitiesandtheoreticalentities.Hackingarguesforrealism

onlyaboutexperimentalentities.Experimentalentitiesareentitiesthatscientistsmanipulateto

studyotherphenomena.Electronsareexperimentalentities,becauseexperimentalphysicists

spraythemtostudyweakneutralcurrents,whicharetheorizedtobecarriedbybosons.Aslogan

HackingcoinsforERis“ifyoucanspraythemthentheyarereal”(1983,23).Inadditiontothe

fact of their existence, Hacking (1983, 265) argues that we can know a modest number of

“home truths” about experimental entities, which consist of thinly theory‐laden low‐level

generalizationsabouttheirwellunderstoodcausalproperties;forexample,theirmass,spin,and

charge. Hacking contrasts these low‐level generalizations or “home truths” with full‐blown

scientifictheoriesaboutunobservables,whicharenotbelief‐worthy.

ERinnotaninnocentdoctrine.ItsignificantlynarrowsthescopeofSR.WhileERleaves

in electrons, photons, protons, andpositrons, it leavesoutneutrino, bosons, andblackholes

(Hacking1989),aswellastheoriesassuch,asopposedtotheentitiesthatpopulatethem.Its

modestyarguablymakesERamoredefensibleposition,but itdissatisfiesmanyrealists,who

wouldlikeSRtohaveawiderscope.

In sum,Hacking’sERdrawsa clear distinctionbetweenobservableandexperimental

entities, aboutwhich realism iswarranted, and everything else. Hacking’s argument for ER,

however,islessclear.Inwhatfollows,Iconsiderfiveinterpretationsofhisargument,starting

withNMA.

Istressthatwithinthispaper,Idistinguishargumenttypesonanepistemicbasis,rather

than structural. I distinguish argument types based on the type of epistemic warrant the

argument confers on its conclusion. I am aware that there are other ways of drawing the

boundariesbetweenarguments.Ialsoacknowledgethatthedistinctionsmaynotbeasclear‐cut

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asIpresentthem.Mychoiceofterminologyforclassifyingargumentstypes,however,shouldnot

hindermysubstantivepoint,whichisthatitispossibletointerpretHacking’sargumentinfive

waysthatdiffersignificantlyinthetypeofepistemicwarranttheyenjoy.

3. TheNMAInterpretation

ThefirstinterpretationofHacking’sargumentforERisasNMA.RecallthatundertheIBEmodel,

we legitimately infer the truth of our best explanation of some given facts. Butwhy arewe

entitledtotreatexplanatorymeritsaslikelinessindicators?Therearevariouspossibleanswers

to thisquestion, butwithin this paper, I adopt the view thatour justification fordoing so is

empiricalandcontextrelative,specifically,relativetoourbackgroundknowledge.Onthisview,

IBEdoesnotnameaformalinference,butanabstractpatternwhoseforceandsuccessdepend

onthespecificbackgroundassumptionsinvolved,andwhosespecificformchangeswithcontext.

Explanatorymeritsareempiricalobservations.Forexample,ifacourtinfersadefendant’sguilt

from the fact that her fingerprints were found in the crime scene, a person matching her

descriptionwasseenfleeingthecrimescene,etc.,thisinferencereflectsthecourt’sknowledge

ofhowcrimesareusuallycommitted.Generallyspeaking,weobserveregularities,seethatsome

events are more frequent than others, and develop our explanatory merits based on these

observations(Ben‐Menahem1990;Day&Kincaid1994).

AgainstPI, realistsmayargue thatnotall empirical success is the same.Realistsmay

distinguishweakfromstrongorgenuineempiricalsuccess.Accordingtothisview,truthexplains

empiricalsuccessonlyif“empiricalsuccessisrobust,significantenough(sufficientlynoveland

abundanttobeinneedforexplanation),andtruthisagood[putative]explanation”(Solomon

2001,25).Realistsmayinsistthatwhiletheremaybeothergoodexplanationsofweakempirical

success,truthisthebestandonlyexplanationofgenuinesuccess.

Ifrealistswanttotakethisroute,however,theyfaceatwofoldchallenge.Theyneedto

show (1) that their criteria for genuine empirical success are principled and non‐question

begging,i.e.,notconstructedadhoctofavourcurrentscience;(2)thatwe,unlikepasthistorical

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actors,areinaprivilegedepistemicpositiontodistinguishgenuinesuccessfromweaksuccess

(Lehoux2012,206‐220).Hacking’sargumentforERmaybeinterpretedasrisingtothistwofold

challenge,andreconstructedasfollows:

(NMA1) Contemporaryexperimentalphysicists’successinmanipulatingexperimental

entities tostudyotherphenomena ismuchmore impressive thanprevious

empirical successes in the history of science in a way that makes it

qualitativelydifferentfromit.

(NMA2) ERistheonlyphilosophythatdoesn’tmakethissuccessamiracle.

(NMA3) Therefore,ERistrue.

Sometextualevidencesupportsthisinterpretation.Clearly,Hackingthinksthatcurrent

experimentalpracticeisqualitativelydifferentfromthatofthe19thcenturyandbefore,suchthat

itcansupportrealisminawaythatpreviouspracticecouldnot:“Anti‐realismaboutatomswas

very sensible… a century ago. Anti‐realism aboutany sub‐microscopic entitieswas a sound

doctrine those days” (1983, 274; emphasis in the origin). “Assumptions about the minute

structure of matter could not be proven then. The only proof could be indirect… Such

indirectnessneedneverproduceconvictioninthephilosopherinclinedtoinstrumentalismor

someotherbrandofidealism”(1983,173).

Hacking writes that we have “evidence” and “proof” for the reality of experimental

entities.ThemoststraightforwardlogicalinferencestructureinwhichHacking’sclaimsabout

experimentalpracticefunctionasevidenceisIBE.YetHackingseemstodenythathisargument

isanIBE,whichseeminglymakestheNMAinterpretationanon‐starter:

Theargument…isnotthatweinfertherealityofelectronsfromoursuccess.Wedonotmake the instruments and then infer the reality of the electrons, as whenwe test ahypothesis,andthenbelieveitbecauseitpassedthetest.Thatgetsthetime‐orderwrong.Bynowwedesignapparatusrelyingonamodestnumberofhometruthsaboutelectronstoproducesomeotherphenomenonthatwewishtoinvestigate(1983,165).

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Onceuponatimethebestreasonforthinkingthatthereareelectionsmighthavebeensuccessinexplanation…Ihavesaidthatabilitytoexplaincarrieslittlewarrantoftruth…Luckilywenolongerhavetopretendtoinferfromexplanatorysuccess(i.e.fromwhatmakes ourminds feel good). Prestcottetal. don’t explainphenomenawith electrons.Theyknowhowtousethem(1983,271‐272).

Nevertheless, I thinktheNMAinterpretationisviable.Wemaydistinguishthetypeof

scientific activity that best supports the reality of electrons (theoretical explanation versus

experimentalmanipulation)fromthetypeofargumentHackingisgivingfortheirreality(IBE

versus another type of argument). The explananda of scientific explanations are specific

phenomenaassociatedwithelectron theories,while theexplanandaof theNMAare “science

itselfanditshistoryofempiricalsuccessasawhole”(Ladyman2014).Clearly,Hackingdenies

thatmereexplanatorysuccessofelectrontheoriessupportstherealityofelectrons.Thisdoes

notmeanthathisownargumentisnotanIBE.Hacking’sargumentmaystillbereadasaNMA.

TheNMAreconstructionconstitutesaprimafaciestrongargumentforSR.Ittakesthe

sting out of PI, bynarrowing the base of the induction in its inductive formulation (PI0), or

denyingpremise(PI1)inthereductioformulation.Additionally,itsconclusionisstrong–itstates

therealityofelectrons,ratherthanmerelythatthebeliefintheirrealityisrational.TheNMA

reconstructionwouldnotconvince,however,thoseantirealistswhorejectthevalidityofIBEin

general.

4. TheIndispensabilityInterpretation

An indispensability argument “purports to establish the truth of some claim based on the

indispensabilityoftheclaiminquestionforcertainpurposes(tobespecifiedbytheparticular

argument)”(Colyvan2014,fn.1).Indispensabilityargumentsareinteraliausedforsupporting

mathematicalPlatonism.Theystatethatreferencetomathematicalentitiesisindispensableto

thepracticeofmathematics,thusweshouldcommittotheirexistence(Colyvan2014).Similar

argumentsexistinmeta‐ethicsfortherealityofmoralnorms(Enoch2011).

Structurally,IBEisanindispensabilityargument,wheretheindispensableclaimsarethe

explanans, and the purpose is explanation. Recall, however, that in this paper, I distinguish

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arguments types on epistemic grounds, rather than structural. Epistemically, IBE and

indispensabilityargumentsthatarenotIBEareoftwotypes,becausetheyconferdifferenttypes

ofepistemicwarrantontheirrespectiveconclusions.AsIusethetermhere,thewarrantofIBE

isempirical.Bycontrast,thewarrantofindispensabilityargumentsthatarenotIBEisgrounded

inthecoherenceofpracticalandepistemicrationality;namely,therequirementforconsistency

betweenbeliefandaction.Ifonecannotavoidactingasifpistrue,thenforthesakeofrationality,

oneshouldbelievethatp.Otherwise,one isguiltyof “intellectualdishonesty” (Putnam1975,

347).4

SomethingsHackingwritesseemtobeinlinewithanindispensabilityinterpretationof

hisargumentforER:

Thevastmajorityofexperimentalphysicistsarerealistsaboutsometheoreticalentities,namelytheonestheyuse.Iclaimthattheycannothelpbeingso(1983,262;italicsintheorigin,boldadded).

As a first approximation, then,Hacking’s indispensability argumentmaybe reconstructedas

follows:

(IA1) Forthepurposeofexperimentallystudyingotherphenomenawecannothelp

treatexperimentalentitiesasreal.

(IA2) Thereforewearerationallycompelledtobelievethatexperimentalentities

exist.

Severaldifficultiesarisewiththisreconstruction.ThefirstisraisedbyHackinghimself:

Evenifexperimentersarerealistsaboutentities,itdoesnotfollowthattheyareright.Perhaps it is a matter of psychology: maybe the very skills that make for a greatexperimentergowithacertaincastofmindthatobjectifieswhateverhethinksabout(1983,265).

Hacking’s reply to this objection is that experimenters do not believe in the reality of all

theoretical entities, only experimental entities. Thus he concludes that experimenters’ 4ThisisnottodenythatanIBEmayhaveadoublewarrant.Idiscussthisoptionin§5.

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compulsiontobelieveinexperimentalentitiesisnotpsychological(1983,265).Hacking’sreply,

however,seemsunsatisfactory.Wemayhypothesizethattheveryskillsthatmakeforagreat

experimentergowithacastofmindthatobjectifieswhatevershethinkssheusesasatool,and

theobjectionstill stands.Asecondproblemwith this reconstruction is that the term“we” is

ambiguous.Whoisrationallycompelledtobelieveinelectrons–onlyexperimenterswhouse

them,or the rest of us aswell? Itdoesnot follow, for instance, from the fact thatpracticing

religiouspeoplearerationallycompelledtobelieveinGodthateverybodyelsemustalsobelieve

in God. Third, there is a gap between claiming that it is rationally required to believe that

electronsexist(anepistemicclaim)toclaimingthatelectronsexist(ametaphysicalclaim).

Aplausiblereconstructionthataddressestheseproblemsisthis:

(IA3) Forthepurposeofexperimentallystudyingotherphenomena,experimental

physicistscannothelptreatexperimentalentities(butnotothertheoretical

entities)asreal.

(IA4) Therefore,theymustrationallybelievethatexperimentalentitiesexist.

(IA4) Forformingrationalbeliefsaboutwhichphysicalentitiesexists,peoplewho

are not experimental physicists must rationally defer to experimental

physicists’epistemicauthority.

(IA5) Therefore,wemustrationallybelievethatexperimentalentitiesexist.

(IA6) Whatwemustrationallybelieveaboutphysicalentitiesistrue.

(IA7) Therefore,experimentalentitiesexist.

Thisimprovedreconstructionraisesotherworries.Regarding(IA4),it iscontroversial

thatlaypeoplemustrationallydefertoexperts’epistemicauthority.Someargueforit(Hardwig

1985);othersrejectit(Goldman2001).Additionally,can’twesimilarlyarguethatforforming

rationalbeliefsaboutreligiousentitieswemustrationallydefertoclergy’sepistemicauthority?

And why are the relevant experts physicists, rather than philosophers, some of whom are

antirealists?(IA6)alsoseemssuspect.Ifitisderivedfromageneralprincipleaccordingtowhich

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whatwearerationallycompelledtobelieveistrue,itseemstoostrong.Iftheclaimappliesonly

tophysicalentities,itseemsadhoc.

Idonotwishtogiveanexhaustivelistofprimafaciedifficultieswiththeargument.My

pointisthatanyplausibleindispensabilityargumentforERwouldseemtoincludecontroversial

premisesthatdonotdirectlybearontheSRdebate,suchasaboutwhenitisrationaltodeferto

expert testimony.Realistsshouldprima facienotcommittoanyparticularstanceaboutsuch

premises.TheprospectsofdevelopingarobustindispensabilityargumentforERthereforeseem

somewhatgrim.

5. TheTranscendentalInterpretation

Transcendentalargumentshaveavenerablehistoryinphilosophy.Theymaybedescribedas

trying to reverse‐engineer reality from appearances. That is, they take as a premise some

obviousfactaboutourmentallifeandproceededtoclaimingthatsomeotherstateofaffairsin

realityisanecessaryconditionforthefirstone.Theyaimatrevealingthenecessaryenabling

conditionsofunquestionableexperiencesortheunquestionablepossessionoremploymentof

somekindofknowledgeorcognitiveability.Theyareoftenusedasrepliestoscepticalclaims

that question the aspects of reality that the transcendental arguments try to establish.

Transcendentalargumentsproceedfromtheirpremisestotheirconclusionbythepreservation

oflogicalornecessarytruths(Bardon2006).

Transcendental arguments, indispensability arguments, and IBEs are sometimes

characterized as belonging to an overlapping family of arguments, since they have a similar

structure.Within thispaper, I distinguishargument typesonepistemicgrounds, rather than

structural, andwant to keep the distinction between them clear. Thus,within this family of

structurallysimilararguments,Icallan“IBE”anargumentwhoseepistemicwarrantisempirical,

an“indispensabilityargument”anargumentwhosewarrantisgroundedintherequirementof

consistencybetweenepistemicandpractical rationality, anda “transcendental argument”an

argumentwhoseepistemicwarrantstemsfromthepreservationoflogicalornecessarytruths

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fromitspremisesto itsconclusion.Thepremisesofa transcendentalargumentforSRwould

typicallyincludesomeuncontroversialclaimsaboutobservables,andtheconclusionwouldbe

totheexistenceofsomeunobservables.

IfHackingmakesatranscendentalargument,itmaybetotheeffectthattheexistenceof

electrons and other unobservable experimental entities is a necessary condition for the

possibility of the experimental practice in the physics laboratory.Morrison (1990, 17),who

suggests a transcendental reading of Hacking’s argument for ER, interprets his argument as

follows:

[T]heargumentforrealismcouldperhapsbeseenasonewhichclaimsthatentitiesandtheirpropertiesmustbepresupposedinsuccessfulpractice;itsimplymakesnosensetodoubttheontologicalandepistemologicalclaimsthatrenderthatpracticemeaningful.5

AccordingtoMorrison’stranscendentalreading,Hacking’sargumentmaybetotheeffect

that“thecommitmentinvolvedinmanipulationisonethat,contraantirealistslikevanFraassen,

involvesmorethanempiricaladequacy”(1990,18),Specifically,Isuggestthatitmaybetothe

effect that the preservation of reference of the term “electron” to electrons (or other

unobservableexperimentalentities)duringradicaltheorychangesisanecessaryconditionfor

thepossibilityoftheexperimentalpracticeHackingdescribes.Tounderstandwhythismaybe

so, recall the challenge that Kuhn (1970) presents to SR of explaining how reference of

unobservable terms is preserved during paradigm shifts, inwhich theirmeaning undergoes

radicalchanges.Toanswerthischallenge,HackingdrawsonPutnam’scausaltheoryofmeaning,

accordingtowhichthereferenceofatermisdeterminedbyacausalchaintoaninitialbaptizing

eventofitsuse,ratherthanaspeaker’sunderstandingofitsmeaning.

Putnam’stheoryonlyexplainshowthepreservationofreferenceispossible.Itisupto

Hackingtoshowthatitispreserved.IfwedrawaparalleltoKant’stranscendentalarguments,

5 According to my taxonomy of argument types, Morrison’s interpretation can also be read as anindispensabilityinterpretation

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wemayinterpretHackingastryingtoshowthis.AsLipton(2003,216)writes,KuhnandKant

sharemuchincommon,butdifferinthatKuhnis“Kantonwheels”:

TheKantianviewisthatthetruthswecanknowaretruthsabouta‘phenomenal’worldthat is the joint product of the ‘things in themselves’ and the organising, conceptualactivityofthehumanmind.Kuhn,however,isKantonwheels.WhereKantheldthatthehumancontributiontothephenomenalworldisinvariant,Kuhn’sviewisthatitchangesfundamentallyacrossascientificrevolution.

IfHackingindeedemploysKant’smethodologyoftranscendentalarguments,itmaythereforebe

for establishing, contra Kuhn, the invariance of reference to experimental entities despite

paradigmshifts,similarlytotheinvarianceofKant’scategories.

WemayfindsomehintsforatranscendentalreadinginHacking’stext.Hackingwrites

thatearlyKantregardedtheoreticalentitiesaspartofthenoumena,andonlylaterabandoned

thisview,realizingitsinconsistencywithhislargerphilosophy.ButthenHackingasks:

WhatpositionoughtKant tohavetakenabouttheoreticalentities thatreallydosomeworkinscience?Whatwouldhehavedonewhen,inthetwentiethcentury,welearnedhowtomanipulateandevensprayelectronsandpositrons?(1983,100‐101)

HackingspeculatesthatKantwouldnothavechangedhisposition,butHackingmaybeinclined

totakeadifferentstance,anduseKant’sownmethodtoprovetheirexistence.

CriticallyevaluatingatranscendentalargumentforERissomewhatdifficult.Thevalidity

ofatranscendentalargumentcruciallydependsonwhetheritpreserveslogicalandnecessary

truthsfromitspremisestoitsconclusionwithoutsmugglingincontroversialhiddenpremises.

Thus, evaluating the validity of a transcendental argument requires a careful scrutiny of an

elaborateformulationoftheargument.ButifHacking’sargumentistranscendental,heprovides

atbestasuggestivesketch,whichisinsufficientforsuchascrutiny.

Moreover,itisunclearifatranscendentalargumentcanbeprovidedforERingeneral,or

whether a separate argument should be provided for the existence of every unobservable

experimental entity. This is because such an argument must start with an uncontroversial

descriptionofanexperimentalpracticeatthelevelofobservableentitiesalone,andthenshow

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that some conclusions about unobservables logically or necessarily follow from it. Since

scientistsmanipulateentitiesinmanywaysandexperimentalpracticesignificantlyvaries,itis

unclear that a generalized description of scientific experimental practice at the level of

observables,whichisrequiredforageneraltranscendentalargumentforER,canbeprovided.

AnotherdifficultywithatranscendentalargumentforERisthatitisunclearwhetherits

conclusion,namely,thattherealityofanunobservableentityisanecessarypresuppositionfor

anexperimentalpracticethatinvolvesitsmanipulation, isrightinlightofapparentempirical

examples to the contrary. Morrison (1990, 9‐13) describes a case in which physicists

manipulatedquarkstostudycharm,whiletheywerestillnotconvincedoftherealityofquarks.

Theconsistencyof thedata theyobtainedservedasa retroactivereason forbelieving in the

existence of both the manipulated and studied entities. For Morrison, this means that

“manipulationcanoccurincontextwheretherearenofirmlyheldbeliefsabouttheentitiesbeing

manipulated” (1990, 9). Even worse, Gelfert (2003) describes in detail a case in which

experimentersmanipulatequasi‐particles,whichtheybelievetobemeretheoreticalconstructs

thatdonotgenuinelyexist.

HackingmightobjectthatMorrison’sexampleisacaseofthe“experimenter’sregress”

(Collins1985),wherethesuccessconditionsforbelievingthatadetectorisworkingproperly

andthatanentityhasinfactbeendetectedarelogicallyinterdependent.Hackingmightobject

that sucha case shouldnotbegiven in supportof SR.Hackingmightargue that the casehe

describesdiffersfromMorrison’squarkcaseinthatthesuccessconditionsforbelievingthatthe

detectionequipmentworksproperlyarelogically independentoftheconditionsforbelieving

thattheexperimentssucceeded.Butthen,onemaywonderwhatissospecialforHackingabout

empiricalsuccess inthephysicslaboratoryasopposedtootherempiricalsuccess.Whatisso

specialaboutsprayingelectronsforstudyingbosons,whichwarrantsabeliefintheirexistence,

asopposedtosprayingelectronsforproducinganimageonanoldCRTtelevision,whichthe

antirealistcandismantlewithherusualargumenttoolkit?

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There is, however, a prominent criticism of transcendental arguments, to which a

transcendentalargumentforERshouldnotbesusceptible.Transcendentalargumentsseemingly

establish,atmost,conclusionsaboutwhatbeliefsarerationalorconceptuallynecessary,butthey

fallshortofestablishingconclusionsabouttheexternalworld,asrealistswouldlike.Because

theirpremisesseeminglyconcernonlysubjects’innerworld,transcendentalargumentscannot

warrant conclusions about the external world, since the conclusions should follow only

deductively or necessarily (Stroud 1968). Thus, a transcendental argument for SR may be

criticisedonthegroundsthatinprincipleitisnotabletoestablishconclusionsaboutwhatexists

intheexternalworld,includingunobservables.

As Grundmann & Misselhorn (2003) argue, however, it is possible to overcome this

problembyintroducingintoatranscendentalargumentaminimalpremiseabouttheexternal

worldthatboththerealistandantirealistwouldfindunobjectionable,andwouldfunctionasa

bridgeprinciplethatestablishesarelationbetweensubjectiveexperienceandobjectivereality.

Within theSR debate, this suggestion looks promising, because scientific antirealists arenot

idealists. They deny neither the existence of a mind‐independent world (M1), nor that

knowledgeaboutobservablesispossible(Chakravartty2013).Thus,inprinciple,itispossibleto

introduceintoatranscendentalargumentforERanuncontroversialpremiseaboutobservables

fromwhichsomeconclusionsaboutunobservableswould logicallyornecessarily follow.For

example,anargumentmayintroducesomeuncontroversialclaimsaboutthe“hometruths”that

areassociatedwithelectronsandcanbeexpressed inobservable termsalone,suchasabout

theirbehaviouraschargedparticles,andderive theexistenceofelectrons,quaunobservable

entities,fromthem.

Howdo the three interpretations ofHacking’s argument that I reviewed so farwork

together?DotheyjointlyprovideastrongercaseforERthaneachofthemprovidesalone?The

first three arguments seem mutually consistent. They all accept the realist commitments

enumerated in §2. Because they enjoy warrants of different kinds, they implicitly rely on

different backgroundassumptionsaboutwhatmakes a claim justified.Whiledifferent, these

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warrants need not be incompatiblewith each other; for example, a claim can have both an

empiricalwarrantandfollowdeductivelyornecessarilyfromuncontroversialpremisesabout

observables.While,asIhaveargued,theindispensabilityargumentrequiresfillinginmissing

premisesthatconcerntheargument’sownscopeandapplicabilityanddonotdirectlybearon

theSRdebate,thereislittlereasontothinkthatthesepremisesneedtobeintensionwiththe

NMA and transcendental arguments. Therefore, the three arguments may work together

providingamorerobustcaseforERthananyofthemprovidesalone.

Yetthemutualcompatibilityandstrengthofthesethreeargumentsdependsalsoonone's

generalphilosophicalcommitments.Notallscientificrealistswouldbewillingtoendorseallthe

threearguments,oranyofthem.Forexample,Maddy(2007,403‐405)arguesthatthetaskof

thescientificrealistphilosopheriscriticallyanalyzingandexplicatingscientists’owndetection

claims of unobservables, rather than adding an extra layer of philosophical analysis and

argumentation to them.Maddy rejects IBEs, transcendental arguments, and indispensability

argument for SR, since she views them as adding such an extra layer of philosophical

argumentation.Thus,shewouldnotsidewithanyofthethreeargumentsreviewedsofar.Ithink,

however,thatMaddyiswrongtorejectIBE,sincescientists'owndetectionclaimsareoftenmost

charitablyinterpretedandexplicatedasIBEs,wheretheexistenceofaparticularunobservable

entityisthebestexplanationofaparticularobservablephenomenon.6Weshouldalsobearin

mindthat IBE isaverycommonformof inference inmanynon‐philosophicalcontexts(Ben‐

Menahem1990). I therefore believe that at least some IBEs for SR are in linewithMaddy’s

philosophical naturalism. If I am right, then a scientific realist who adheres to Maddy’s

philosophicalmethodologymightaccepttheNMAargumentforER,butrejectthetranscendental

andindispensabilityarguments.

6Infact,itishardtointerpretMaddy’s(2007,406)ownexplicationandanalysisofPerrin’sargumentfortheexistenceofatomsotherthanasanIBE.EvenaccordingtoMaddy'sownaccount,PerrininferredtheexistenceofunobservableatomsfromthefactthattheyproducedanobservablepatternthatwasidenticaltothepatternofBrownianmotionofobservableentities,wheretheproductionofsuchBrownianmotionbyatomshadbeenanovelpredictionofstatisticalthermodynamics.

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I have so far suggested three different interpretations of Hacking’s argument for ER,

which enjoy epistemicwarrants of different kinds. I have argued thatwhile different, these

interpretationsneednotnecessarilybeintensionwitheachother.Inthenexttwosections,I

review two additional interpretations – the Vichian interpretation, and the no‐argument

interpretation,andarguethattheystandintensionwiththefirstthreeinterpretationsaswellas

witheachother.

6. TheVichianInterpretation

For reviewing the fourth interpretation, consider the following excerpt from Hacking

(1983,247):

Thebestkindsofevidencefortherealityofapostulatedorinferredentityisthatwecanbegintomeasureitorotherwiseunderstanditscausalpowers.Thebestevidence,inturn,thatwehave thiskindofunderstanding is thatwecansetout, fromscratch, tobuildmachinesthatwillworkfairlyreliably,takingadvantageofthiscausalnexus.

ThisechoesItalianphilosopherVico’sMaker’sTheoryofKnowledge.Vico(1668‐1744)

equates truthwithmaking(“verum ipsum factum”),andarguesthat inasmuchasweproduce

something, we also know its causes and understand its true principles. “The verum‐factum

principledefinesknowledgeorscienceaspre‐eminentlycausal incharacterandas therefore

concernedwiththegenesisorconstructionofaphenomenon”(Zagorin1984,18).7

Boon & Knuuttila (2011) sympathetically read Hacking in this spirit. They interpret

Hacking as claiming that a mere mirroring (isomorphism, similarity, etc.) notion of

representation,whichdominates thephilosophyof science, is emptywithout an intervening

component.Theepistemic valueofmodels lies inourability tomanipulate them forgaining

knowledgeabouttheworldorusethemtomanipulatetheworld.Boon&Knuuttila(2011,87)

write:

7IthankYemimaBen‐MenachemfordrawingmyattentiontotheresemblancebetweenHackingandVico.

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…takingacuefromHacking,wesuggestthattherepresentationalidiomdoesnotdescribeadequately our actual theoretical practices, which instead of trying to accuratelyrepresenttheworld,aremoretunedtoouractiveengagementwiththeworldthanwhatiscustomarilysupposed.

WemayreconstructHacking’sVichianargumentasfollows:

(VA1) Experimenters reliably produce phenomena by manipulating the causal

powersofelectrons.

(VA2) Havingsuchcausalmanipulativeabilitiesisasufficientconditionforhaving

knowledgeofelectrons,whereknowledgeentailstruth.

(VA3) Havingknowledgeofelectronsentailshavingknowledgethatelectronsexist.

(VA4) Therefore,experimentersknowthatelectronsexist.

(VA5) Therefore,electronsexist.

ThewarrantofthisargumentisgroundedinwhateverprinciplesunderlieVico’sMaker

TheoryofKnowledge.Thus,(VA2)seemstocarrytheepistemicweightoftheargument.Vico

thinksthathumanscanonlyhaveknowledgeofthehumanworld,becauseonlyGodproduces

natural phenomena. As Carrier (2011, 48‐52) argues, however, we nowadays study non‐

naturallyoccurringphenomenaofourownmaking,andusethemtostudyotherphenomenaas

well.Carrierdoubts,however,thatcausalmanipulativeabilitiesaresufficientforknowledgefor

two reasons. First, sometimes scientists know how to produce certain effects without fully

understanding theunderling causal dynamics at play. Second,manipulative ability is usually

consistentlyachievedundercertainbackgroundconditions,andscientistsdonotalwaysknow

howchangingthemwouldaffecttheoutcome.

TheVichianargumentdoesnotsquarenicelywiththefirstthreeinterpretationsorwith

thestandardrealistcommitments.Vico’sequationoftruthwithmakingviolatesSRcommitment

to a non‐epistemic theory of truth (S2). That is, the Vichian argument is framed within an

anthropocentricepistemologythatequatestruthwithmaking,yetrealistsholdthatthetruth

valuesofclaimsisindependentofthehumanabilitytotestorverifythem.AccordingtoHacking,

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hisownERcanbeexpressedintermsofacorrespondencetheoryoftruthorsomethinglikeit

(1988,291).

Moreover, a Vichian framework forms a hierarchy of knowability, which seems

incompatiblewith thehierarchyassumedwithin theSRdebate.Thoughmanyargue that the

lines between observable and unobservable entities are blurry, it is still generally assumed

within the SR debate that observable entities are on more secure epistemic grounds than

unobservable.Thatis,allsidestothedebateacceptthatwehaveknowledgeofobservables,and

thedebateconcernsunobservables.Manipulabilitydrawstheepistemiclinesdifferentlyfrom

observability.Itplacesmanipulatableentities,suchasunobservableelectronsandobservable

car engines, higher on its epistemic hierarchy than non‐manipulatable entities, such as

unobservablebosonsandobservablehurricanes.

IdonotsuggestthataVichianepistemologyandthestandardSRassumptionscannotbe

reconciledwith eachother ifonehasenoughphilosophicalmotivationand free time. Sucha

reconciliation,however,wouldhavetosignificantlyrelaxtherealistcommitments,toanextent

thatitwouldbeunclearifERcouldstill legitimatelybecalled“realism”,bearinginmindthat

becauseERisantirealistabouttheories,itisalreadyamodestrealistposition.Alternatively,such

areconciliationwouldtakethewindoutoftheMaker’sTheoryofKnowledge,becauseitwould

havetorelaxitsanthropocentricfocus,whichmakesitattractivetobeginwith.Thus,arobust

caseforERthatincludesaVichianlineofargumentseemsunpromising.

7. TheNon‐ArgumentInterpretation

ThelastinterpretationofHacking’sargumentisthatitisnotanargumentatall,asHackingdoes

not think that an argument can establish the reality of electrons. Rather, the experimental

practicedirectlyillustratestheirreality.Accordingtothisinterpretation,theepistemicwarrant

forERliesindirectlyperceivingthelaboratorypractice,ratherthananyfeatureofanargument

forit.Accordingtothisreading,therootsofHacking’s(non)argument

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lieintheanti‐theoreticaltraditionsofpragmatismandinthecommonsensicalreactiontoBerkeley'sidealismmadefamousbySamuelJohnson.WhenJohnsonmanipulatedastonewithhisfootheatonceaffirmedthatthestonewasmorethanameretheoreticalconstructandthathewaswarrantedinapplyingcommonsensereasoningtoaffirmitsexistence(LyonsandClarke2002,xx‐xxi).

ThisreadingaccordswiththefactthatHackingdoesnotgiveanexplicitargumentforER,

butgivesadetailedvividdescriptionoftheexperimentalpracticeinthephysicslaboratory.It

alsoaccordswithHacking’sdepictionofhisconversationwithaphysicist,inwhichthephysicist

saidphysicistsspraypositrons,andafterwhichHackingbecamearealist(1983,23).

Insuggestingthisinterpretation,IfollowGreco’sinterpretationofMoore’sfamousproof

ofanexternalworld,inwhichMoore(1962,144)gestureswithhishandswhilesaying“hereis

onehand”and “here isanother”,and thendeduces theexistenceofanexternalworld.Greco

(2002)arguesthattheepistemicforceofMoore’sproofdoesnotlieinanyfeatureofMoore’s

argument,but in thedirectperceptionofanundeniable fact, i.e.,Moore’shands.Grecoreads

Moore’sargumentasplayful,whereMoore’sverypoint is thatwedonotknowthatexternal

thingsexistbyprovingthis,butbyperceivingthem.ThisissimilartoBrown’s(1997)claimthat

somepicturesconstituteinandbythemselvesmathematicalproofs,becausetheyallowpeople

todirectlyperceivethetruthofamathematicaltheorem,withoutneedingtotranslatethemto,

oraccompanythemwithanargument.

Thisinterpretationdoesnotrequireareconstruction,butwemayfollowGreco’sMoore

andgivethefollowingreconstruction,whichshouldbereadplayfully:

(NA1) Experimenterssprayelectrons.

(NA2) Therefore,electronsexist.

The non‐argument interpretation returns SR to its common‐sense roots. Before SR

shatteredintocountlesspositionswithhair‐splittingepistemicandonticdistinctionsbetween

them, itwasconsideredacommon‐sensephilosophy,whichtakesourbestscienceat its face

value, and elucidates scientists’ own philosophy. In particular, it was the common‐sense

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responsetologicalempiricists’elaboratetakeonscientificclaims,theirtruth,andtheirmeaning.

Yet,onemayquestionthecommonsensicalstatusofknowledgeofunobservableentities,such

aselectrons,asopposedtoobservableentities,suchasMoore’shands.Inresponse,Hackingmay

argue that forexperimentersand thosewhostudy them,knowledgeofelectronsbecomesas

commonsensicalasknowledgeofone’shands.Theprospectsofsuchasuggestionneedfurther

exploring.

Therearedifficulties reconciling thenon‐argumentargument forERwith the rest.As

Morrisonobserves,ifweacceptthetranscendentalinterpretation,“wemustdismissHacking's

claimthatmanipulationoffersdirectproofoftherealityofentities”(1990,18).Thesamewould

applytoalltherestoftheinterpretationstoo.Accordingtothenon‐argumentinterpretation,the

rest of the arguments commit a category mistake: they try to prove with a philosophical

argument what can only be proven with a direct unmediated physical demonstration. The

non‐argumentinterpretation,then,nullifiesanyotherphilosophicalargumentsforER.Itthus

cannotbeintegratedwithinarobustcaseforER.

8. Conclusion

WhileHacking’scatchyslogan“ifyoucanspraythemthentheyarereal”seems intuitiveand

persuasive, and Hacking’s argument for Entity Realism seems simple and straightforward,

appearancescanbemisleading.IdistinguishedfivepossiblereadingsofHacking’sargumentfor

EntityRealismbasedontheepistemicrationalethatunderliesthem:(1)ano‐miraclesargument,

whose epistemic warrant is empirical; (2) an indispensability argument, whose warrant is

groundedintherequirementofconsistencybetweenepistemicandpracticalrationality;(3)a

transcendentalargument,whosewarrantisgroundedinthepreservationoflogicalornecessary

truthsfromasetofuncontroversialpremisestoitsconclusion;(4)aVichianargument,whose

warrant isgrounded inanepistemology in thespiritofVico’sMaker’sTheoryofKnowledge,

whichconnectstruthwithmaking;(5)anon‐argument,wheretheepistemicwarrantdoesnot

lieinanyfeatureofaphilosophicalargumentforEntityRealism,butinthedirectunmediated

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demonstrationpoweroftheexperimentalpracticeinthephysicslaboratory.Theversionofthe

argumentascientificrealistwouldliketosidewith,ifany,dependsondeepissuesattheheart

ofthedebate,suchasthenatureoftruth,representation,andknowledge.

Acknowledgements

I thank Anjan Chakravartty, Jacob Stegenga, Yemima Ben‐Menachem, and Daniel Steel forhelpfulcommentsanddiscussions.ThispaperwaspresentedattheIsraelSocietyforHistoryandPhilosophyofScienceAnnualMeeting,Jerusalem,2013,andatthePSABiennialMeeting,Chicago,2014.Ithanktheaudiencemembersforhelpfulcomments.IamgratefultothestudentsatmyseminarinphilosophyofscienceattheBarIlanUniversityGraduatePrograminScience,Technology,andSocietyforrealizingthatgettingatthebottomofHacking’sargumentistricky.IthanktheDanDavidFoundation,theCohnInstitutefortheHistoryandPhilosophyofScienceandIdeas,TelAvivUniversity,andtheSidneyM.EdelsteinCenterforHistoryandPhilosophyofScience, Technology and Medicine, the Hebrew University of Jerusalem, for postdoctoralfellowships.

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