Last Chance Saloons for Natural Kind Realism Anjan ... · Traditionally, accounts of natural kinds...
Transcript of Last Chance Saloons for Natural Kind Realism Anjan ... · Traditionally, accounts of natural kinds...
Last Chance Saloons for Natural Kind Realism
Anjan Chakravartty University of Miami
Abstract Traditionally,accountsofnaturalkindshaverunthegamutfromstronglyconventionalisttostronglyrealistviews.Recently,however,therehasbeenasignificantshifttowardmoreconventionalist-soundingpositions,even(perhapsespecially)amongphilosophersinterestedinscientificclassification.Theimpetusforthisisatrendtowardmakinganthropocentricfeaturesofcategories,namely,capacitiestofacilitatehumanepistemic(andother)interestsviainductiveinference,centraltoanaccountofkinds.Iarguethattakingthesefeaturesseriouslyisbothdefensibleandcompatiblewithconventionalism,butnotcompatiblewithatraditionalrealismaboutkindsspecifically.Moreover,hopesofachievingcompatibilitybyrevisingandextendingkindrealism–intowhatIcall‘hyperrealism’–faceaninsuperabledilemma.Thenewsforrealistsisnotallbad,however:thoughkindrealismprovesuntenable,closelyassociatedrealismsunderlyingtheobjectivityofkinddiscoursemaybeviablenonetheless.Keywords naturalkinds•conventionalism•constructivism•deflationism•realism•hyperrealism•naturalness•scientificrealism1. A traditional framework for thinking about natural kinds
Somuchhasbeensaidabouttheideaofnaturalkinds–theancientnotionthattheworldis
inhabitedbynaturalcategoriesofthings–thatonemightnowexpectthebroadoutlineofcoherent
versionsofthisideatobelargelytransparent.Iwillargueinwhatfollows,however,thatthisisnot
entirelyso,atleastconcerningthemorespecificideaofrealismaboutnaturalkinds.Itisarguable
thattheideaofnaturalkindrealismhasbecomelesstransparentinrecentdecades.Myaiminthis
paperistountanglewhatItaketobesomeconfusionhereand,intheprocess,describeandassess
whatprospectsremainforrealismaboutkindsspecifically,thatis,forrealismaboutputativekind
categoriesthemselves.Discussionsofrealisminthiscontexthavebeensusceptibletoconfusionin
partbecausecontrastingviewsofkindsalltendtoinvolverealismaboutsomething,andthis
somethingisoftenconflated,inappropriately,withkindcategories,orsoIwillsuggest.
Asafirstpass,thenotionofnaturalkindsisusuallyspelledoutintermsofgroupsofentities
(e.g.,objects,events,processes)whosemembershavesomepropertyorpropertiesincommon.
Differentviewsofkindselaboratethisbasicideainanumberofdifferentways,seekingtoanswer
differentquestionsandwithdifferentconceptionsoftherelevanttermsofart.Withthisinmind,
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andsoasnottogetlostinthethicketbeforewedigin,letmebeginbyrestrictingthefocusand
clarifyingmyownuseofsomekeyterminology.Theprimaryconnotationsofrealismare
compatible(Ibelieve)withdifferentpositionsregardingmanyotherdebatesaboutkinds.For
example,giventhefirstpassatkindssketchedaboveintermsofsharedproperties:someholdthat
thesepropertiesareintrinsic,othersthattheymayalsobeextrinsic;somethinkthattheycomprise
essences(i.e.,theyareindividuallynecessaryandjointlysufficientforkindhood),othersthat
variableclustersofpropertiessuffice;somedisputewhetherkindsareparticularsorsetsof
particularsoruniversals(andifuniversals,whethersimpleorcomplexorboth).Leavingallofthese
detailstooneside,myfocushereisthebigger-picture,foundationalquestionofwhatitmeanstobe
arealistaboutkinds,andwhetherthetraditionalconceptionofthisviewisdefensible.
Tacklingthisfoundationalquestionrequiresanengagementwithbothmetaphysicaland
epistemologicalissues,whichinturnrequiressometerminologicalclarification.Traditionallyand
generically,‘realism’denotesabeliefinthemind-independentexistenceofsomething.Adetailed
treatmentofthisideaexceedsmyaimshere,butaroughcharacterizationwillserveforpresent
purposes:tosaythatsomethingexistsmindindependentlyistosaythatitsexistencedoesnot
dependonitsbeingthoughttoexist.Onthisunderstanding,someofwhatarecommonlylabelled
‘socialkinds’or‘humankinds’(e.g.,groupswhosememberssharesocialorpsychological
properties)mightwellseem,primafacie,toexistmindindependently,thoughnotall(e.g.,money,
theexistenceofwhichquamoneydependsonitsbeingconceivedassuch).Similarly,atleastsome
ofwhatarecommonlyregardedasartifacts–birds’nests,geneticallymodifiedorganisms,
especiallyheavyelements,novelchemicalcompounds,etc.–whosecomingintoexistencemay
dependonthoughtintheformofintentionsandactsofcreation,mightwellseemtoexistinamind-
independentwayoncecreated.Thereismuchtodebateinconfrontingfiner-grainedcontroversies
engenderedbythesesortsofexamples,withconsequencesforfiner-grainedelaborationsofmind
independence,butthebasicideaofexistingindependentlyofbeingthoughttoexistisallthatwill
beneededhere.Realismaboutkindsisthustheviewthatkindsthemselves–therelevant
categories1–existindependentlyofbeingthoughttoexist.
Granted,thereareotherwaysonemightproceed,butalsosignificantreasonstodoubtthat
theyarecompelling.Forinstance,takingissuewithmycharacterizationofmind-independent
existence,onemightregardasminddependentanykindinvolvinghumanmindsorthoughts
1Cf.Bird&Tobin(2018),whoclarifythenotionofrealismaboutnaturalkindsintermsoftheexistenceofkindsspecificallyas‘aspecialsortofentityinourontology’.
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simpliciter.2However,thisseemsclearlytomistaketherelevantsenseofmindindependence.The
existenceofmentalproperties,forexample,maydependontheexistenceofminds,butpresumably,
giventhatmindsexist,theexistenceofmanyormostmentalproperties(whatevertheymaybe)
doesnotdependonwhetherorhowwethinkaboutthem.Itisthelattersenseofmind
independencethatisrelevanttorealism,andevenhumanmindsmayhavemind-independent
propertiesinthissense.Primafacie,kindsdefinedintermsofsuchpropertieswouldthusseem
appropriatecandidates,atleast,forrealismasitistraditionallyconceived.Inanycase,noneofthe
argumentstofollowwillhangonanymoreprecisestipulationsregardingmindindependence,or
theoutcomesoffiner-graineddebatesinvolvingsuchstipulations.
WhatIhavejustidentifiedasatraditionalunderstandingofrealismimmediatelygives
shapetoatraditionalframeworkforthinkingaboutkindrealism,anditsdenial.Themind-
dependentexistenceofsomethingentailsthatitsbeingthoughttoexistisanecessaryconditionof
itsexistence;inotherwords,therelevantthinkingisconstitutiveoftheexistenceofthekind.Letus
callviewsthattakenaturalkindstoexistminddependentlythusconstruedconventionalist.
Historically,viewsofnaturalkindsmaybeseenaspopulatingaspectrumfromstrongly
conventionalistviewsatoneextreme,tostronglyrealistviewsattheother.Theterm‘subjective’is
oftenappliedtokindsinconnectionwithconventionalismand‘objective’usedlikewisein
connectionwithrealism.Iwillsimplytakethesetermstobesynonymousfor‘minddependent’and
‘mindindependent’,respectively.
Asafinalclarification,itisworthnotingthattheterm‘natural’in‘naturalkind’isitself
ambiguous.Inmuchwritingaboutkinds,‘natural’istakentobeellipticalfor‘mindindependent’or
‘objective’,andthusasindicativeofsomethingamenabletorealism.Ontheotherhand,itisnot
unusualforconventionaliststousetheterm‘naturalkind’,notinconjunctionwithrealism
exclusively,butmerelyasanameforthosecategorieswhosestatusasmindindependentor
dependentissubjecttophilosophicalconsideration.Inthisuse,theterm‘natural’carriesno
implicationofbeingconducivetorealism.Itismerelyalabelforthetopicunderdiscussion–the
categoriesweusetoclassify,taxonomize,andsoon.Whileitisgenerallyclearfromthecontext
whichoftheseusesisintended,toavoidanyconfusionIwillsimplyusetheterm‘kind’henceforth,
andconsiderthenotionofnaturalnessseparatelywhenitarises.
Insection2,Iexaminetheideathatepistemicsuccess–morespecifically,thesuccessof
variousformsofinductiveinference–isproperly,intimatelyconnectedtotheorizingaboutkinds.I
2SeeEreshefsky2018,pp.845-846,fordiscussionandreferences.Cf.Slater2013,p.22;Franklin-Hall2015,pp.927-928;andKhalidi2013,sections4.5and6.5.
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willsuggestthatthisissoforbothconventionalismandrealism,thoughfordifferentreasons,and
defendtheideathatinductivesuccessisageneralmarkerofgenuinekindhoodagainstsomerecent
objections.Insection3,Iscrutinizethenatureofthisconnectionmorepreciselyfor
conventionalism,settingthestageforaparallelexercisewithrespecttorealisminsection4.Iargue
thatbyfocusingattentionontheconnectionbetweenkindsandinductionandintakingitseriously,
anuntenableaspectofearlierapproachestorealismisilluminated.Theupshotofthisforrealism
hasbeenmuddled:viewsthatcallthemselves‘realist’butnotinthemanneroftraditionalrealism,
leavingthestatusofrealismaboutkindsspecificallysomewhatambiguous,orviewsthatsimply
lapseintoconventionalism.OnemayattempttorevisetraditionalrealisminfavorofwhatIwillcall
‘hyperrealism’,discussedinsection5.Hyperrealism,however,facesafataldilemmaconcerning
naturalness.Insection6Iconcludebyreflectingonwherethisleavestheprospectofrealism.
2. Inductive virtues as indicators of genuine kindhood
Whatisthemotivationforentertainingthepossibilitythattherearekindsinthefirstplace?
Differentaccountsofferdifferingmotivations,butonecommonlycitedelementistheideaof
accountingfortheepistemicsuccessthatinvestigatingandreasoningabouttheworldintermsof
certaincategoriesaffords.3Thisiswhy,asnotedearlier,thequestionofkindrealismisonewhose
assessmentinvolvesbothmetaphysicalandepistemologicalissues.Themetaphysicaldimensionis
apparentimmediatelyintheoppositionbetweenrealismandconventionalismandthe
correspondingtask,onanygivenversionoftheseapproaches,ofspellingouthowexactlyit
incorporatesthenotionofmindindependenceordependence.Theepistemologicaldimensionis
lesstransparentbutneverthelessinextricable.Thefactthatkindsarepositedtoaccountfor
epistemicsuccessultimatelyplacesconstraintsonwhatkindsaretakentobe,becausethe
epistemicsuccessthatsomecategoriesaffordandothersdonotamountstoarepositoryof
empiricaldataforthinkingaboutthenatureofkinds.
Asananalogy,considerhowscientificrealismisgenerallyheldtohavebothmetaphysical
andepistemologicaldimensions–themetaphysicaldimensionconcerningthemind-independent
existenceofvariousthingsdescribedbyourbestscientifictheories(oftencouchedinothersterms,
suchastheapproximatetruthorsuccessfulreferenceofthosedescriptions),andthe
3Thisassertsthecentralityofepistemicinterestsbutdoesnotpreclude,ofcourse,therelevanceandimportanceofnon-epistemicintereststothinkingaboutkinds.Oftentheformerarethemeansbywhichwehopetoservethelatter,aswellaspracticalandpragmaticinterests.
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epistemologicaldimensionimplicitintheappealto‘ourbesttheories’.Ourbesttheories,scientific
realistsandantirealistsagree,areourmostsuccessfultheories:thosethataffordthemostaccurate
andreliablepredictions,retrodictions,generalizations,andexplanations.Twopointsarehelpful
hereintheanalogytokinds.First,alloftheactivitiesassociatedwithsuccessfulsciencelistedabove
areoutputsof,orunderwrittenby,inductivereasoning.Second,bothrealistsandantirealistsabout
sciencetakethisasadatum;theiraccountsofwhatweshouldbelieveinscientificcontextscanbe
viewedaswaysofparsingandexplainingthisinductivesuccess.Dataregardingtherelativesuccess
ofdifferenttheoriesisaninputforbothrealistandantirealisttheorizingaboutscience,resultingin
differentoutputs.
Realismandconventionalismaboutkindsparallelthesefeaturesofrealismandantirealism
aboutscience.Theinductivesuccessaffordedbycertaincategoriesisadatumthatonemaywishto
explain.Indebatesbetweenscientificrealistsandantirealists,theformersometimesthinkofthisin
termsofa‘miracleargument’,ormoregenerallyassomethingakintoatranscendentalargument.
Inotherwords,somescientificrealistsarguethatthebestexplanationofthesuccessofatheory–
perhapstheonlygoodornon-miraculousexplanation,ifnotquiteanecessaryprecondition–isthe
mind-independentexistenceofwhateverisputativelydescribedbythattheory.Scientific
antirealistscounterwithrivalaccountsofsuccess.Similarlyandtraditionally,realistsaboutkinds
explaininductivesuccessintermsofourhavingcarved,inthemannerofanepistemicsamurai,at
nature’sownjoints,toinvokethePlatonicmetaphor.Conventionalistsaboutkindsexplainsuccess
differently,intermsofcategoriesthataremerelyusefulinconnectionwithourvariousinductive
purposes.Intheirdifferentways,bothtakeinductivesuccesstobeastandardmarkerorindicator
ofgenuinekindhood(butseefootnote3).Takingsuccessinhumanepistemicpursuitsseriouslyis
thusrelevanttotheorizingaboutkindswhateverpositiononetakesinthetraditionalrangeof
positionsmappedoutbyconventionalismandrealism.
Ihavebelaboredthispointaboutthecentralroleofinductivesuccessintheorizingabout
kindsbecauseitiscrucialtowhatfollows,buttheideathatthereissomesuchconnectionhasnot
generallybeencontroversial.Exploringconceptuallinkagesbetweenkindsandinductionisa
themethatappearsfromantiquitytothepresent(seeHacking2007forahistoricalsweep).Inthe
immediatebackgroundofcontemporarydiscussions,HilaryKornblith(1993,p.7)contendedthat
‘Thecausalstructureoftheworldasexhibitedinnaturalkinds…providesthenaturalgroundof
inductiveinference’,andRichardBoyd(1999,p.146)suggestedthat‘Itisatruismthatthe
philosophicaltheoryofnaturalkindsisabouthowclassificatoryschemescometocontributetothe
epistemicreliabilityofinductiveandexplanatorypractices.’Morerecently,P.D.Magnus(2012,
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chapter1)constructsanimpressivelistofelevendifferentideasassociatedwithkindshistorically,
butthemostwidelyacceptedone–andtheonlyone(apartfromtwomorecontroversialideas
motivatinghisownparticularview)hefindstobesufficientlywellmotivatedtoinformour
theorizingaboutthem–is‘theinductionassumption’.4
Allofthissaid,thereisatleastsomerecentresistancetotheinductionassumptionbasedon
examiningourmodernconceptionofwhatwasconsidered,inancienttimes,anexemplarycaseof
kinds:biologicaltaxa.MarcEreshefskyandThomasReydon(2015,pp.977-8)associatetheclaim
thatkindsaregroupsofthingsthatsupportinductiveinferenceswiththeideathatmembersofa
kindshareasignificantnumberofrelevantproperties(Iwillreturntothisideainsection5),which
thenunderwritesinductivepracticessuchaspredictionandgeneralization.Thethought,
presumably,isthatitisbecauseofthissubstantialsharingthatweareoftensuccessfulinforming
expectationsaboutonememberofakindonthebasisofknowledgeofanother.However,twoofthe
mostprominentapproachestoclassifyingtaxaincontemporarybiology–Cladismand
EvolutionaryTaxonomy–regardthemashistoricallineagesoforganisms,eachdescendedfroma
commonancestor,andoverlongenoughperiodsoftime,thepropertiesoforganismsatdifferent
timeslicesalongalineagemaydiffersignificantly.
Furthermore,tomakemattersworsefortheinductivist,ontheseundeniablyimportant
approachestobiologicaltaxonomy,itisoftenthecasethatwhenapopulationoforganisms
branchesofffromitsparentpopulation–theymightbeseparated,forexample,asaresultofa
weathereventorvolcanicactivity–theorganismsintheparentspeciesandthenewspecieswill
shareasubstantialnumberofbiologicallyrelevantproperties.Andthoughtheyhavenowbeenre-
classifiedastwodifferentspecies,thissubstantialsharingofpropertiesmaycontinuefora
significantperiodoftime.FromthisEreshefskyandReydon(p.978,footnote4)concludethatnot
allscientificclassificationislinkedtoinduction,asopposedtodifferentaims.Moreover,‘tolimit
naturalkindstothosekindsthatfeatureinsuccessfulinferentialpractices…isanaprioriapproach
tonaturalkindsthatdoesnotdojusticetotheepistemicpracticesofscientists’.
Thisskepticismaboutinduction,however,isunfoundedonbothcounts.Regardingthefirst
charge,thatinductivesuccessisimmaterialtotheorizingaboutkindsinatleastsomecases,crucial
weighthereisbornebythesuggestionthat‘differentaims’maybeservedinstead.Inthecaseof
CladismandEvolutionaryTaxonomy,‘theaim…istoclassifydistinctbranchesontheTreeofLife’
4Magnus2012,p.8:‘Acentralassumptionaboutnaturalkinds–thecanonicalassumption–isthatyoucanmakeinductiveinferencesaboutthem.…Thisissharedsowidelythatanyreasonableaccountofnaturalkindsmustvindicateit.’
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(p.977).Buttowhatends?Biologicaltaxonomyisnotstampcollecting.Itservesinductivesuccess.
Thepointofdemarcatingonthebasisoflineagesisnottoidentifybranchesonatreeforitsown
sakeandstopthere,butrathertoidentifygroupsoforganismsthatareevolutionarilysignificant:
onesthataresubject,ascollectivesovertime,tobiologicalprocessesdescribedintermsof
parametersincludingselection,adaptation,andgeneticdrift.Investigatingandilluminatingallof
thisinvolvesinductivereasoningintheserviceofretrodictionsandevolutionaryexplanations
regardingthosekinds.Thesecategoriesoforganismsthusfacilitatebiologicallyimportant,
inductiveinferences.
PerhapswhatEreshefskyandReydonhaveinmindintheircritiqueisaparticularformof
induction.‘Induction’,afterall,isatermofart.Atoneextreme,onemightuseittorefervery
specificallyandexclusivelytoenumerativeinduction;atanotherextreme,itmayrefertoanynon-
deductiveorampliativeinference.Whatisappropriateinthiscontext,however,isneitherextreme,
butratherafocusoninductivereasoningthatisdirectlyrelevanttothepresumedvalueof
theorizingabouttherelevantkindsasguidestolearningabouttheworld.Onthisbasis,itisdifficult
toseehowthemeaningof‘induction’couldberestrictedsuchthatspecies,ashistoricallineages,do
notfacilitatescientificallymotivatedinductivesuccess.Takethemembersofaspecies,S,toshare
thepropertyofdescentfromacommonancestor,A.Thepredicate‘descendedfromA’isinductively
projectible.ItiscentraltoinductiveinvestigationsofrelationsbetweenmembersofS,betweenS
andotherspecies,andbetweenthemembersofdifferentspecies.Theserelationsarekeyto
understandingevolutionaryphenomena,andbyinvestigatingthemwegaininsightinto,andform
expectationsof,therelevantkindsandtheirmembers.Isitplausibletoexcludethisfromthescope
ofwhatcountsasinductivesuccess?ThefactthatsomeintrinsicpropertiesofmembersofSmay
changeovertime,ormaybesharedacrossspeciesatatime,hardlyunderminesinferencesthatare
integraltolearningaboutspeciescategoriesinevolutionarybiology.Toexcludetheseinferences
wouldbetooperatewithastrangelyimpoverishednotionofinduction.5
WhataboutEreshefskyandReydon’ssecondworry,thatthinkingofkindsascategories
‘thatfeatureinsuccessfulinferentialpractices’isapriori?Well,clearlyitis,inonesense;butinthis
senseanyaccountofkindsisboundtobe.AmomentagoIdescribedtheveryideathatthereare
5SeeKhalidiforthcomingon‘etiologicalkinds’,‘whosememberssharea…causalorigin,history,ortrajectory’ratherthanintrinsicproperties,andyetserveretrodictiveandexplanatorypurposesinvolvingancestralrelationsandcausalprocesses.Andarguably,thoughBoyd(1999,2010)takeskindmemberstosharepropertyclustersthatremainlargelystableviacausalmechanisms(despitepossiblevarianceovertime),healsoseemstooperatewithabroaderconceptionofinductivesuccess,commonlyadvertingto‘inductiveandexplanatorysuccess’or‘inductive/explanatorysuccess’.Causalexplanationsdepend,ofcourse,oninductiveinferencesestablishingtherelevantcausalrelationships.
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kindsastheupshotofsomethingakintoamiracleargumentoratranscendentalargument.Kinds
arepositedtohelpexplaininductivesuccess.Exhypothesi,itwouldbeincredibleifourinductive
practicesweresosuccessfulandyetnottrackinggenuinecategories;orperhapstheexistenceof
suchcategoriesisahighlyintuitiveorcrediblepreconditionforinductivesuccess.Butevenifone
weretocontendinsteadthatkindsarepositedtoexplainsomeotherfeatureof(say)scientific
practice–eitherway–thissortoftheorizingispartofthemetaphysicsofscience,wheresubject
mattersarenotinanyverystrictsenseaposteriori.Thisismerelytosaythatatheoryofkindsisa
philosophicaltheory.Andinanycase,giventhestructureofamiracleargumentoratranscendental
argument,alinkbetweenkindsandinductioncannotbeconsideredaprioriintoto.Kindhood,after
all,ispositedtohelpexplaintheempiricaldataofinductivesuccess,andasnotedabove,thesesame
datainformhowwethinkaboutkinds.
Havingexploredanddefendedthetraditionalideathatinductivesuccessisreasonably
consideredageneralmarkerofkindhood,letmereturnnowtothethoughtthatconventionalists
andrealistsoffercontrastingdiagnosesofhowexactlythissuccessisrealized.Herethemind-
dependent,mind-independentdistinctionloomslarge.Inordertoseewhy,asIwillargue,realism
aboutkindshasfallenonhardtimes,itwillbehelpfulfirsttoconsiderhowconventionalism
connectskindsandinduction.Thiswillserveasapreludetoseeinghowrecentarticulationsof
realismflirtwithorcollapseintoconventionalism.
3. Conventionalism regarding our knowledge of the world
Theprimarymoralofthefollowing,briefattentiontoconventionalismisthatevennon-
realistviewsofkindsareoftenandperhapstypicallyrealistaboutsomething,justnotaboutkinds
themselves–anobservationthatwillultimatelypaydividendsforthinkingaboutwhatadefensible
realisminthevicinityofkindscanamountto,ifanything.Forthemoment,recallthatthe
distinctionbetweenconventionalismandrealismis,atitscore,adistinctionconcerningthe
dependenceorlackthereofofkindcategoriesonaparticularsortofmentalstateoractivity:
conventionalismholdsthatthesecategoriesexistinvirtueofourthinkingthattheydo,andrealism
demurs.Thesearegeneralformulasfortwobroadfamiliesofviews,allowingformorespecific
versionswithineach.Letmeillustratethisfirstinconnectionwithconventionalism.
Ausefulwayofelaboratingthetraditionalnotionofamind-dependentkindisintermsof
twocentralconnotationsofthisidea,thedenialofwhichisacentralfeatureoftraditionalrealism.
Letmelabeltheseconnotations‘constructivism’and‘deflationism’.Itisaconsequenceofthefact
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thattherearedifferentwaysofconstructingandthusdeflatingkindsthatminddependencetakes
differentforms.Constructivismisthataspectofconventionalistviewsaccordingtowhichwhat
makesagroupakindisthefactthatwerecognizeitascomprisingagenuinecategory,thereby
constructingitskindhood.Inthisway,ourholdingsomethingtobeakindisconstitutiveofits
kindhood.Deflationisanimmediateconsequenceofconstruction.Deflationistsaboutxaretypically
antirealistsregardingthewayxhasbeen(perhapstraditionally)characterized–thatis,inarealist
way.Forexample,deflationistsabouttruthareantirealistsabouttruthconceivedasapropertyof
thingssuchaspropositionsorbeliefs.Theyholdthattraditional,realistunderstandingsoftruthare
mistakenormisleading;theyshouldbereplacedbyaviewthatrecastsrealistunderstandingsinto
something(putatively)lessmetaphysicallyheftyorweighty.
Asanillustrationofthissortofconstructionandconcomitantdeflation,considerThomas
Kuhn’s(1970/1962)historicistinterpretationofthenatureofscientificknowledge.OnKuhn’s
view,notmerelyscientificknowledgebuttheworlditself,duringanygivenperiodofrelative
stabilityinascientificcommunity,is(inpart)constitutedbysetsofsharedrelationsbetweenideas
–aboutsymbolicgeneralizations,metaphysics,values,problem-solvingexemplars,etc.These
matricesofcommitmentsareconstructedandheldcollectivelybycommunities,whichimbuethem
withacertainstatus,amountingtoaconstructionoftheworld(pp.111,121,150).Anything
resemblingatraditionalrealistunderstandingofscientificontology,involvingdescriptionsofand
referencetomind-independententities,isthusdeflatedintosetsofhistoricallycontingentrelations
ofideas.Similarly–hencetheidentificationoftheseviewsasmembersofabroaderfamilyqua
kinds–sociologistsofscientificknowledgeoftenrecastrealistontologyintosocioeconomicand
politicalstatusesandrelations,andsomefollowinginthelogicalempiricistandpragmatist
traditionsmayrecastitintermsofutility-drivenchoicesoflinguisticframeworks.6
Whatalloftheseversionsofconventionalismhaveincommonisaneo-Kantiankernel.One
wayofexemplifyingthisisintermsofamaximallygeneralsortofrealismabouttheexistenceofan
externalreality:thereisaworldoutthere,itexistsindependentlyofus,butitisepistemically
hubristictoimaginethatwecandescribeitasitis,noumenally.Successfulepistemicpracticesare
correlatedwiththismind-independentrealityinsomeway,suchthatourcategoriesworkwellfor
scientificorotherpurposes,butthatisallwecansayaboutthenoumena.Anotherversioncleaves
totheideathatourinabilitytodescribetheworldasitisinitselfisnotamatterofepistemic
humilitybutratherstemsfromthefactthattheverynotionofaworldindependentofconstructive
6Foradiverserangeofinfluentialtakesonconventionalism,seeGoodman1975,Rorty1980,andPutnam1983.
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conceptionsisincoherent,whichrulesoutanysortofrealismtraditionallyconstrued.Eitherway,
thegeneralityofbothoftheseversionsconventionalismentailsaconventionalismaboutkinds:we
cansaynothingaboutthenoumena;afortiori,wecansaynothingaboutnoumenalkinds.Crucially,
however,givenourmorespecificfocushereonkinds,wemayaddtothislandscapeof
conventionalistpossibilitiesamorediscerning,thirdoption:aconventionalismaboutkinds
specifically(perhapsinteralia),combinedwitharealismaboutcertainotheraspectsofreality.7
Whicheverversionofkindconventionalismoneadopts,onemayofcoursedescribethe
phenomenalworldmakingupourempiricalrealityinanthropomorphicwayswithrespecttokinds,
andevensuccessfullysofarasinductionisconcerned.Whatonecannotorshouldnotattemptto
assertisanythingontologicallydefinitiveaboutostensiblynoumenalkindsinvirtueofwhichour
inductivepracticesaresuccessful.Rather,itisourthinkingthatacategoryisgenuine,ideally
supportedbyasubstantialorotherwisesignificantdegreeofinductivesuccess,thatmakesitakind.
Onceagain,ananalogytodebatesaboutscientificrealismmaybehelpful,thistimein
illustratinghowadeflationaryattitudetowardonethingmayresultinarecastingthatembodiesa
differentsortofrealismaltogether.Inresponsetoskepticalworriesaboutunobservableentities
describedbyscientifictheories,JohnWorrall(2007)arguesthatscientificrealistsshouldsimply
endorsetheRamseysentencestructureofourbesttheoriesinstead.ToformtheRamseysentence
ofatheory,wesubstituteitstermsforputativeunobservableswithexistentiallyquantified
predicatevariables,andvoilà,theskepticism-fuelingcontenthasbeendisplaced,allowingrealists
tofocusontherelationalstructureofthetheoryinstead.Butnote:intheprocess,therealismat
issuehasshiftedprofoundly.Whatwasarealismaboutunobservableentitieshasbeenrecastinto
somethingratherdifferent.Thevariablesneednotreferinanydeterminateway.Onemightsaythat
theworld,aboutwhichoneisarealist,isjustsuchthattherelationsexpressedintheRamsey
sentenceobtain;thisjudgmentwouldreflectthe(inductive)successassociatedwithourbest
theories.Similarly,aconventionalistaboutkindssaysthatwhatrealistsregardasmind-
independentkindsshouldberecast.Perhapstheworldissimplysuchthatourclaimsaboutcertain
categoriesprovesuccessful,orperhapsrealismaboutsomeotheraspectsoftheworldunderwrite
thissuccess.Eitherway,itisourrecognitionofthecategoriesthatmakesthemkinds.
Letmeextracttwothoughtsfromthisbriefoverviewofconventionalism.First,asinthe
caseofrealism,conventionalismiscompatiblewithtakinginductivesuccesstobeageneralmarker
ofkindhood.Itisjustthatonthelatterview,thisindicatorrevealsnothingsubstantial(ornothing
7Afterconcludingmyargumentagainstkindrealism,insection5,section6willsuggestthecombinedoptionastheonlypossibilityremainingforthoseinclinedtowardarealistdiscourseofkinds.
Chakravartty Natural Kind Realism
11
atall)aboutkindhooditself–theexistenceofacategory–thatwouldqualifyasmindindependent,
owingtoitsconstructivismandassociateddeflationism.Second,leavingasidethequestionof
whetherWorrall’spositionisreallyaformofscientificrealism,theanalogyintimatedbythis
questionisnonethelesssuggestive.Iwillreturntoitinsection6,whereIconsiderwhetherthereis
anypositionthatisbothdefensibleandsufficientlyrealistaboutkindsspecificallytomeritthe
label.JustasWorrallattemptstoweakentraditionalformulationsofscientificrealisminreplyto
skepticalconcerns,thereisstrongmotivationamongkindrealiststoweakentraditionalformsof
kindrealism,anditwillbehelpfulinwhatfollowstoretainthethoughtthatrealismregardingthe
existenceofamind-independentworld,orcertainaspectsoftheworldsuchasparticulars,
properties,causalrelations,laws,etc.,doesnotbyitselfamounttoarealismaboutkinds.
4. Updating traditional realism: ambiguity and collapse
Ihaveelaboratedthecentraltenetofconventionalism,theminddependenceofkinds,in
termsoftwomainconnotations,constructivismanddeflationism.Realismandthemind
independenceofkindsmayalsobeelaboratedintermsoftwomainconnotations:thedenialofboth
constructivismanddeflationism.Itisunsurprising,perhaps,thatonreflection,mindindependence
ismostobviouslycharacterizedinthisnegativeway,foralthoughtheassertionthatakindexists
independentlyofitsbeingthoughttoexistisasubstantialmetaphysicalclaim,itisnoteasyto
expandonitwithamoredetailed,positivecharacterizationthatalsosucceedsinexplainingthe
intimateconnectionbetweenkindsandinductivesuccess.Iwillfocusonthiscontentionshortly(in
section5),buttosetthestage,letusmoveforwardwithourworkingcharacterization,accordingto
whichrealismaboutkindsisconceivedasdiametricallyopposedtoconventionalismintermsofthe
principalconnotationsnotedabove.
HereIaimtomotivatetheideathatsayingsomethingmoreaboutthemind-independent
natureofkindsisforceduponrealistsassoonastheyattempttosquarethemetaphysicaland
epistemologicaldimensionsoftheirrealism–thatis,mindindependenceandinductivesuccess.In
arguingforthisIwillciteanumberofrecentlydevelopedviews,andmuststronglyemphasizeat
theoutsetthatitisnotentirelyclearwhetheranyofthemis,infact,intendedtobecompatiblewith
kindrealismasIhavedescribedit,traditionally;someareclearlynotsointended.Whatisclearis
thatalloftheirauthorstakethemselvestobepresentingviewsthatareinsomewayrealist,evenif
itisnotalwaystransparentwhethertherealismatissueattachestokindcategoriesspecifically,to
somethingelse,ortoboth.Furthermore,forallIsayinwhatfollows,theymaybecoherentviews.
Chakravartty Natural Kind Realism
12
Myaimissimplytosuggestthatthesein-some-way-realistorpossibly-kind-realist-compatible
viewsareeither(1)ambiguousquarealismaboutkindsthemselves,or(2)conventionalist,the
surfacedescriptionsofthesepositionsnotwithstanding.
Amonganumberofnowlargelyabandonedideasassociatedwiththerealisttraditionof
theorizingaboutkinds,oneinparticularhassufferedgreatlyinrecentdecades:theideathatkinds
formaunique,hierarchicalsystemofcategorieswithstrictsubsumption,accordingtowhich‘ifany
twokindsoverlap,thenonemustbesubsumedundertheotherasasubkind’(Tobin2010,p.179).
Thisportraitofamonistickindstructureoftheworldhasnowbeenwidelysurrendered,notleast
becauseofthedifficultyofmakingsenseofitinthecontextofthesciences–presumablyan
exemplarysetofinvestigationsforrevealingkinds–wherewhatwecommonlyfindarenotunique
hierarchicalsystems,butratherdifferent,co-existingsystemswhosecategoriesoftencrosscutone
another,violatingtheconditionofstrictsubsumptionandsuggestingapluralisticportraitofkind
structureinstead.Awidelydiscussedillustrationofthisisthecaseofbiologicalspecies.Acrossthe
breadthofthefield,biologistsdonotclassifyorganismsintospeciesinonlyoneway.They
taxonomizeonthebasisoflineages(aswehaveseen),butalsoonthebasisofreproductivefertility,
ecologicalroles,andinotherways.Theconsensusdiagnosisofthispluralisminpracticeisthat
differenttaxonomicsystemsneednotbeincompetitionwithoneanother,butsimplybettersuited
topursuingdifferentaims.Differentformsofinductivesuccessareoftenbetterachievedusing
differentclassificatorysystems,evenwithinadomain.8
Giventheimplausibilityofthetraditionalrealistpictureofasinglesubsumptive
classificatorysystem,kindrealismrequiresanupdateinthisrespect.Butwhatsort?Ifthe(mind-
independent)existenceofkindsistobepartofanexplanationofinductivesuccess,andthesuccess
ofcertainscientificpracticesisatleastpartofthisexplanandum,anyupdatetokindrealismmust
takethesepracticesseriously.This,however,ispreciselywhererecentdiscussionshave
underminedprospectsforrealismaboutkindsspecifically,fortakingscientific-inductivesuccess
seriouslyhasresultedinpositionsthatare,Isubmit,eitherambiguousregardingtheirendorsement
ofmind-independentkindcategories,orseeminglyrealistaboutthingsotherthankinds.Letus
focusfirstonpossibleambiguities:descriptionsofkindsthatdonotmerelylinkthemtoscientific
practice,butalsoflirtwiththesuggestionthatthispracticeisinsomewayresponsiblefor
8Thereisabundantsupportforthisconsensus.SeeKitcher1984,Ereshefsky1992,andDupré1993forearlierworkonspeciespluralisminbiology.Khalidi1998andTobin2010arguethatuniquehierarchicaltaxonomywithsubsumptionisunderminedbycrosscuttinginthesciencesmoregenerally.Ruphy2010exploresthevarietyofwaysstarsareclassifiedwithdifferentpredictiveandexplanatorygoalsinmind.Longino2013detailsfourdifferentapproachestostudyinghumanaggressionandsexuality,eachofwhich‘parses’causalfactorsindifferentways.
Chakravartty Natural Kind Realism
13
constructingtherelevantkinds.AsIwillnowillustrate,thisamountstoanambiguitybetween,on
theonehand,simplynotingthatourinterests–aims,goals,purposesofinquiry,questionsposed,
answerssought–maybebetterservedbytheorizingintermsofonetaxonomyratherthananother
(whichiscompatiblewithmindindependence),andontheotherhand,takingourintereststobe
constitutiveofkindhood(whichisnot).
Letmelabelthetwosidesofthisambiguity.Onthefirsthand,humanthinkingaboutkinds
entersonlyintheacknowledgmentofaprocessoffiltration:ourinterestsalignwithpracticesthat
filterout,amongthevariouskindsandsystemsofkindsthatexistindependentlyofourthinking
theydo,theonesthatwehope(andideally)aretheonesbestsuitedtosuccessfulinductive
inferencesinrelationtothoseinterests.Letuscallthisa‘filteringapproach’totakingscientific-
inductivesuccessseriously;ourinterestspromptustotriangulateon,andsofacilitatethefiltering
of,mind-independentkinds.Onthesecondhand,humanthinkingaboutkindsentersinthemanner
ofalathe:ourinterestsalignwithpracticesthatultimatelyshapeandtherebyconstructakindor
systemofkindsthatexistsbecauseourthinkingaboutthesecategorieshypostatizesorreifiesthem.
Letuscallthisa‘constitutingapproach’totakingscientific-inductivesuccessseriously;our
interestspromptustofashionkindsthatwehope(andideally)arewellsuitedtosuccessful
inductiveinferencesmadeinrelationtothem.Somerecentworkthatmaybeviewedasattempting
toupdatethekindrealisttraditiongivestheimpression,Ithink,ofwobblingontheborderbetween
filteringandconstituting.
Consider,forexample,Magnus’(2012)account.Hebeginsbynotingthat‘different
enquiriesrequirecuttingalongdifferentjoints’(p.1).Thissuggestsfiltering–thePlatonic
metaphoriscustomarilyinvokedtoconveytheideathatkindsaremindindependent–andinthis
spirithelaterconfirmsthat‘whether[kinds]aretheredoesnotdependonus’(p.119).These
remarks,however,bookendsomewhatenigmaticadditions:‘Itisaconstraintonouraccountof
naturalkinds…thattheyformcomponentsofsuccessfulscientifictaxonomy’(p.20).Now,fromthe
pointofviewoffiltering,thismightseemtoputthecartbeforethehorse.Thesciencesareableto
triangulateoncertaincategoriesbecausetheyexist;theydonotexistbecausetheyfigurein
scientifictaxonomy.Magnus’intentionhereseemsdifferentinitially:nottosaythatkindhood
dependsonscientifictheorizingandpractice,butthat‘anaccount’ofkindssodepends–areading
thatechoesmycontentionearlierthattheorizingaboutkindsisnotentirelyapriori,sinceitis
informedbytheempiricaldataofinductivepractice.Butthenheappearstoshiftintothemodeof
constituting:‘Insofarasscienceissomethingwedo,thenaturalkinds…willbethingsthatdepend
onus’(p.20),aswellasontheworld‘insomeway’(p.26).Otherclaimsmightbereadasconflating
Chakravartty Natural Kind Realism
14
filteringandconstituting:‘thenaturalkindsweidentifymayberealquanaturalkindsand
dependentonusquaouridentifying’(p.104).Butiftheexistenceofakinddependsonour
identifyingitassuch,thenitdoesnotexistmindindependently.
Again,letmeemphasizethatthejuxtapositionofthesequotationsisnotintendedcritically,
butmerelytoillustratethestraininvolvedinattemptingtoupdatekindrealisminawaythatdoes
justicetotheroleofinductivesuccessintheorizingaboutkinds.Ambiguityregardingthecore
stickingpointbetweentraditionalrealismandconventionalism,namely,mindindependence,is
hardlyasurprisingconsequence.MatthewSlater(2013,pp.171-176)seemsunequivocalinhis
rejectionoftraditionalrealism:itisamistake,hethinks,toregardkindsascomprisingan
ontologicalcategory;kindhoodissimplyastatusconferredonacategorywithinadomainof
inquiryonthebasisofitservingwhateverepistemicinterestsarepresentthere.Thisrelativizes
kindhoodtointerestsandinvestigations,whichsuggestsconstituting,butevenso,adegreeof
ambiguityconcerningrealismcreepsin:‘thecontributionsofouraimsandinterestsplaya
parameter-settingrolewithoutsaturatingtheresultantkindswithsubjectivity’(pp.171-172).
Thereinliestherub.Saturationadmitsofdegrees;mind-independentexistencedoesnot.Attempts
tomergekindrealismwithtaxonomicpluralismbymeldingmindindependenceanddependencein
descriptionsofkindshasproducedacertainamountofambiguitywithrespecttorealism.
Whilehintsofrealismappearinaccountsofkindsthatedgetowardconventionalism,some
donotedgesomuchasstraightforwardlyrelinquishtheirrealistcredentialsregardingkinds
specifically.AclearexampleofthelatterisBoyd’s(2010,p.220)accountof‘accommodation’,on
whichkindtalkisunderstoodintermsofameshingoftaxonomicpracticesandcausality:‘the
theoryofnaturalkindsjustis(nothingbut)thetheoryofhowaccommodationis(sometimes)
achievedbetweenourlinguistic,classificatory,andinferentialpracticesandthecausalstructureof
theworld.Anaturalkindisnothing(much)overandaboveanaturalkindtermtogetherwithits
useinthesatisfactionofaccommodationdemands.’Boydelaboratesthisbysayingthat‘natural
kindsaresocialconstructions’;‘Inacertainsensetheyaremind,interest,andprojectdependent.’
Asnotedearlier,claimssuchastheseareslogansforconventionalism.Theysatisfythegeneral
formulaofneo-Kantianconstructivism,accordingtowhichkindsarejointfeaturesoftheworldand
ourminds.Granted,manyimplementationsofthisformulataketheworldinitselftobemind
independent,butthisdoesnotalterthefactthatanyviewonwhichtheexistenceofsomethingis
partiallyconstitutedbyourthinkingthatitexistsisaformofconstructivism–whichis,recall,a
principalconnotationofconventionalism.
Chakravartty Natural Kind Realism
15
Boyd(2010,p.221)iskeentoavoidthisdiagnosisandrejectsthesuspicionthat
accommodationiscomparabletoaneo-KantianconstructivismàlaKuhn,onthebasisthat‘human
conceptualandinferentialpracticesmustbeaccommodatedtothecausalstructuresofthe
phenomenaunderstudy,notviceversa’;‘humansocialpracticesmakenonon-causalcontribution
tocausalpropertiesandrelationsintheworld’.Butthissuggestsonlythathisnotionof
accommodationisnotwelldescribedbyaparticularinterpretationofKuhn,notthatitisrealist
aboutkinds.Realismaboutvariousthingsinrelationtocausation–causalproperties,causal
relations,causalstructures–issimplynotthesamethingas,nordoesitrequire,realismregarding
kindcategories.Causationisoftenanalyzed,forinstance,asarelationbetweeneventsorfacts,oras
aprocess,butnoneofthesebroadapproachestothemetaphysicsofcausationentailsrealismwith
respecttokinds.
Similarly,Reydon(2016,p.60),whiletakingaclearstandonthequestionoffilteringversus
constituting–‘kindsaremadebyus,ratherthansimplyfoundinnature’–neverthelessassertsthat
thisshouldbeacceptabletokindrealists.Onhis‘co-creationmodel’,‘bothnatureandwe–asthose
whodotheclassifying–fundamentallycontributetothecreationofkinds’(p.70);kindsare‘co-
determinedbyaspectsofthestateofaffairsinnatureaswellasbybackgroundassumptionsand
decisionsbyinvestigators’(p.59).Butagain,arealismaboutaspectsofstatesofaffairsdoesnot
entailarealismaboutkindsunlesskindsthemselvesarecountedamongtherelevant(mind-
independent)aspects.Onceonegoestherouteofkindconstructivism,evenifsomeofthe
componentmaterialsoutofwhichkindsareconstructedaremindindependent,realismregarding
theexistenceofthecategoriesthemselveshasbeendeflated.
Itisfair,Ithink,towondernowwhetherthisismerelyaterminologicaldispute:doesit
concernnothingmorethanadisagreementabouthowtodefine‘realismaboutkinds’?Idonot
thinkso.Havingnotedthatunderstanding‘realism’intermsofmind-independentexistencereflects
adeeplyentrenched,historicaltraditionofuse,myconcernhereisnottopreservetradition;itisto
investigatewhetherkindrealismthusunderstoodisviable.TheviewsIhavejustdiscussedareby
nomeansexhaustiveofrecentthinkingthatmayappearambiguousinthislight,orthatamountto
conventionalism.Theyare,however,representativeofatrendinwhichthelabel‘realism’hasbeen
appliedlooselywherekindsareconcerned–somuchsothatoncloserexamination,thoughthey
maybeviewed(inatleastsomecases)asattemptstoupdatetherealisttraditionoftheorizing
aboutkindssoastogivedueweighttoinductivesuccess,theycannotbeseen(clearlyoratall)as
remainingwithinthattradition,asunderstoodintermsofitsmostcentralcommitments,tothe
mind-independentexistenceofkindsandarejectionofconstructivismanddeflationism.Letus
Chakravartty Natural Kind Realism
16
moveonnowtoconsiderwhatprospectsmayyetsurviveforkindrealismonastricteradherence
tothesecommitments.
5. Hyperrealism: bridled versus unbridled promiscuity
Iftheideaofamind-independentexistenceforkindsistobeadoptedstrictlyratherthan
finessed,themetaphoroffilteringinvokedintheprevioussectionmustbemarriedtothe
taxonomicpluralismwefindinherentininductivesuccess.Asperrealism,filteringisaprocess
wherebyinductivepracticestriangulateonmind-independentcategories:kindsthatexist
independentlyofourinterestsandscientificdisciplinesarediscernedandselected,oftenvia
painstakinginvestigationandtrialanderrorovertime,fromamongother(sometimescross-
cutting)categoriesofthingsthatmaylikewiseexistmindindependently.Thetraditional,kind-
realistconvictionthatkindsare“outthere”isintendedtodojusticetothisprocessoffiltering
throughempiricalinquiry.Ratherthanmoveinthedirectionofconventionalism,thestalwart
realistholdsthattherearemanycrosscuttingcategoriesofentitiesthatexistindependentlyof
beingthoughttoexist.Sincethisamountstoanextendedapplicationofthecorecommitmentof
mindindependencetoamuchbroaderclassofcategoriesthanwasonceendorsedbyrealistsonthe
nowoutmodedconceptionofaunique,subsumptivetaxonomyofkinds,letuscallthisposition
‘hyperrealism’.
Thoughhyperrealismisclearlyanextensionofanearlierincarnationofrealism,thevery
ideaofitraisesaquestionaboutitsproperextent.Thismightbenarrowlyconstruedasa
metaphysicalquestionwithacorrespondinglynarrowanswer:theproperextentofhyperrealismis
limitedtothosekindsthatare,infact,mindindependent.However,itistheepistemological
dimensionofrealismthatisatissuehere.Takingscientific-inductivesuccesstobeindicativeof
mind-independentkindsinpracticedoesnotbyitselfamounttoclearguidanceregardingwhat
formsofinductivesuccessshouldbeconsideredthusindicativeinprinciple.Actualscientific
practicecomprisesanegligibleproportionofpossiblescientificpractice,whichmay(forallwe
know)involvedifferentformsofinductiveinferenceandstandardsofsuccess.Furthermore,one
maywonderwhetherinductivesuccessisproperlyconsideredmorelikelyindicativeofkindhood
whenitoccursinthesciencesasopposedtoothercontexts,manyofwhichinvolveinquirythatis
alsoinductivelysuccessfulandsometimeshighlysystematic.Herewefinddramaticallyconflicting
intuitionsabouttheproperscopeofhyperrealism,andthepositionfacesaseriouschallenge.Iwill
Chakravartty Natural Kind Realism
17
nowsuggestthatanyattempttodeterminetheproperextentoftheviewfacesadilemma,with
conventionalismloomingononesideandincoherenceontheother.
LetmeframethisargumentwithanexampleintroducedintorecentdiscussionsbyJohn
Dupré(1993,pp.29-30).Dupré’s‘promiscuousrealism’wasinpartareactiontotheideathatonly
categoriesdelimitedbythesciencesaregenuinekinds.Hisbasiccontentionwasthatwhilethe
sciencesmaywelltrackkinds,thereisultimatelynodefensiblereasontothinkthatscientific
taxonomyisuniqueinthisrespect.Ifthefolkcategory‘fish’includeswhales,andthiscategoryso
configuredsupportsinductiveprojectionsthatarerelevanttothefolk(say,fisherfolk),itisthen
arguablyagenuinekind,evenifscientistsclassifywhales,whicharemammals,inaseparate
categoryfromfish,whicharenot.Folkandscientificcategoriesareoftenexamplesofcross-cutting
kinds.Onemightworry,ofcourse,thatinourmodernscientificerathisexampledoesnotpumpthe
intuitionsitwouldhaveearlier.Perhapsthefolkconcept‘fish’nowexcludeswhalesformost
people;thisaspectofscientifictaxonomymaynowhavebeenabsorbedintobroaderlinguistic
practice.Inthatcase,wemightpumptherelevantintuitionssimplybyimaginingatimebeforethis
wasthecase,orbyhelpingourselvestoanynumberofcontemporaryexamples.9
Herewemustfinallyconfronttheissueof“naturalness”.Earlier,toavoidconfusion,I
promisedtousetheterm‘kind’sansqualificationuntilitwasnecessarytodootherwise,because
‘naturalkind’isusedbyrealistsandconventionalistsalikebutindifferentways.Now,however,let
usfocusonpossibleinvocationsofnaturalnessasanotiontowhichhyperrealistsmightappealin
ordertodelimittheproperextentoftheirposition.Recallthat‘natural’,inthiscontextofrealist
usage,routinelyfunctionsasasynonymfor‘objective’or‘mindindependent’.Clearly,though,ifthis
synonymyexhauststhemeaningoftheterm,naturalnesscannotfunctionasanindependent
criterionforrecognizingwhatismindindependent,becauseonthisusage,tosaythatsomethingis
naturalistosaynothingmorethanthatitismindindependent.Inorderthatnaturalnessfunction
asahelpfulindicatorofmindindependence,itmustbesomethingthatwecanapprehendinitsown
right.Thisisthecruxofthedifficultyforhyperrealism.Attemptstospecifytheproperextentofthe
viewallendup,onewayoranother,appealingtotheideathatsomecategoriesarenaturaland
othersarenot(someevenclaimthatcategoriescanbemoreorlessnatural).Butlackingan
9Ludwig(2017)considerscasesfromethnobiology,thestudyofhoworganismsareunderstoodindifferentcultures.E.g.,itiscommoninindigenoustaxonomiestoclassifybatstogetherwithbirds,contrabiologicalsystematics.Thisishardlysurprisinggivenamultitudeofinductiveinferencesunderwrittenbytheircommonalities:‘bothtypicallyhavewings,alightbonestructure,akeeledsternum,asimilarsizerange,streamlinedbodies,highmetabolism,migratorybehaviour,similarnaturalenemies,afruit-andinsect-baseddiet,andtheybothtypicallyfly,disperseseedsintheenvironment,reducelocalinsectbiomass,andsoon’(p.193).
Chakravartty Natural Kind Realism
18
understandingofnaturalnessthataffordssuchjudgments,theseappealshavenoprobativeforce,
andasIwillnowcontend,thereisnosuchunderstanding.
Presumably,inordertodiscernthepresenceorabsenceofnaturalnesshere,weshould
havesomewayofevaluatingand/ortrackingcategoriesfroma“nature’s-eye”pointofview.Thisis
whereconflictingintuitionssurfaceregardingwhatsuchavantagepointwouldreveal,butthe
challengeforhyperrealismisevenmoreseverethanthismightsuggest.Thefataldifficultyisthat
welackanunderstandingofnaturalnessthatiscapableofdoingtheworkforwhichitisrequired:
namely,tospecifyanindicatorofmindindependencethatismorediscriminatingthan(mere)
inductivesuccess.Anycandidateforgenuinekindhoodwillbeassociatedwithsomesuchsuccess–
whetherwithinoroutwiththesciences,inactualityorpossibility,etc.–soifnaturalnessistobe
calledupontoestablishtheproperextentofhyperrealism,itmustbeafeatureofonlysomesuch
categories;thatis,afeatureofsomebutnotallcategoriesthatfacilitateinductivesuccess(orthat
woulddosounderappropriateinvestigationalcircumstances).Whatmightthisbe?
Considerfirstthepossibilitythatevenwithoutgivingaqualitativedescriptionof
naturalness,wemightsimplytrackthetrulynaturalkindsbytakingthesciencestobeexclusive
arbitersofgenuinekindhood.Ifsuchdeferenceweredefensible,thismightserveasabasisfor
puttingabridleonpromiscuity–injustthewayDuprétriedtoresist.However,giventhatinductive
successissufficienttonominateacandidatekind,andlackingadescriptionofnaturalnesswith
whichtoexplainwhyscientificcategoriesarenaturalandextra-scientificonesarenot,itisdifficult
toseehowablanketdeferencetosciencecouldbewarranted.Perhapsthehyperrealistcouldtake
inspirationfromEreshefskyandReydon’s(2015,p.984)claimthatitwouldbewrongtothinkthat
theterms‘fish’and‘Mammalia’(forinstance)bothrefertonaturalkinds,becausefolkbiologyand
scientificbiologyarecompetingtaxonomicprograms,andthelatterispreferablebecause‘The
categoryfishisnotpartofanycurrentprogressiveclassificatoryprogram.’Butthiswillnothelp,
foratleasttworeasons.First,sincethefolkcategoryandthescientificcategorysupportdifferent
sortsofinductiveinferences,andthus(notsurprisingly)servedifferentaims,itisamistaketo
thinkofthemasbeingincompetition.Second,whilethequestionofwhetheraclassificatory
programisprogressiveordegenerating,touseImreLakatos’celebratedterminology,maybe
aproposofscientificresearchprograms(asLakatosintended),itcutsnoicehere.Thatdistinction
wasneverintendedtosetlimitsonwhatisnatural.10
10Forthemakingsofanother,possiblechallengetotheideaofconstraininghyperrealismbydeferringtoscience,seeConix2019,pp.31-33,whoarguesthatgiventhewayclassifications(e.g.,ofspecies)mayvaryaccordingtolocalaimsandnorms,andinterpretationsandoperationalizationsofsharednorms,scientifictaxonomyitselfplacesnoconstraintsontheextentofhyperrealism.
Chakravartty Natural Kind Realism
19
Letusbroadenourthinkingaboutwhichcategoriesexemplifynaturalness,then,beyonda
blanketdeferencetothesciences.Intheabsenceofacompellingdescriptionofwhatnaturalnessis,
however,thetaskofdelimitingthesecategoriesremainselusive.MuhammadAliKhalidi(2013,p.
62)suggeststhatwhileplacingwhalesinthecategoryoffishmayservecertaininductivepurposes,
‘notallpurposesarecreatedequal’.Doesthismeananythingfromanature’seyepointofview?Itis
difficulttoseewhyorhowthepurposesofevolutionarysystematistsaresuperiorquanaturalness
tothepurposesoffisherfolkoreco-tourists.Khalidiassertsthatsomepurposesareepistemically
superiorwithrespecttodesideratasuchaspredictionandexplanation,andthat‘ourbestepistemic
practicesaimtouncoverthedivisionsthatexistinnature’(p.63).Butasastrategyfordelimiting
whatisnatural,thisfaresnobetterthandeferringtoscience,becauseitishighlysuspecttoimagine
thatthereisanyabsolutesenseinwhichjudgmentsofcomparativeepistemicgoodness
(‘superiority’)canbemade.Theinherentaimsofinvestigativecontextsdeterminewhatinductive
inferencesandknowledgearebestthere–andthisvariesbetweencontexts,whetherinthe
sciencesorotherwise.Thereisnosuchthingasanabsoluteorcontext-freemeasureofepistemic
superiority,andtoassumeotherwisemerelythreatenstobegthequestion.
Otherattemptstoidentifycategoriesimbuedwithnaturalnessindirectly–thatis,while
lackinganaccountofnaturalnessitself–arelikewiseunconvincing.Onestrategyistoappealto
intuitivenotionsofsignificanceorimportance:itisobviousonintuitivegrounds,somehave
claimed,thatsomecategoriesrepresentsignificantorimportantcollectionsofthingsandothersdo
not.Ifthiswereso,onemightthendefinetheproperextentofhyperrealismintermsofcategories
that,invirtueofcomprisingsignificantorimportantcollections,arejudgednatural.Thisseems
desperate,though,forsignificanceandimportanceareparadigmexamplesofanthropocentric
qualities.Andtoreturntoanowpredictabletheme,judgmentsaboutwhatisorisnotsignificantor
importantarecontext-relative,notabsolute.Imagineaddingallofthenowunforeseencontextsof
futureinvestigation(letalonethoseofallpossibleinterest)tocontextsofcurrentinterest,whether
inthesciencesorbeyond;thenotionthatwhatappearsimportantatanygiventimeorplaceisan
indicatorofthelimitsofwhatisnaturalnowseemsallthemorecontrived.Similarskepticism
awaitspossiblevariationsonthethemeofimportance.AviewoftencreditedtoMill(1846,PartI,
chapter7,section4),forinstance,isthatwhatmakesakindnaturalisthesharingoflargenumbers
ofsignificantproperties.Whythisshoulddelimitwhatisnatural,however,isopaque.11
11Theviewisalsoimplausible.Themembersofmanycanonicalscientifickinds(e.g.,subatomicparticles,chemicalelements)shareonlyafewdistinctiveproperties.Howmanyissufficientfornaturalness?Icannotdiscussfurthervariationshere,butwillflagonemore:someconstrue‘importance’as‘informativeness’,whichhasbeenelaboratedininformationtheory.Ross&Ladyman(2007,pp.196-238)buildonDennett’s
Chakravartty Natural Kind Realism
20
Theupshotofthisdiscussionisadilemmaforhyperrealism.Themotivationfortheposition
iscompelling:onceweappreciatethedepthofconnectionbetweenpositingkindsandinductive
success,scientificandotherclassificatorypracticesinevitablydrivekindrealisminamore
pluralisticdirectionthanwasoncethenorm.Thisrealization,however,immediatelyraisesa
seriousquestionregardingwhetherthereareanyconstraintsatall,beyondinductivesuccess,on
whatisproperlyrecognizedasakindasperrealism(cf.Lemeire2018).Therearetwooptionshere
forhyperrealism.Aswehaveseen,onemayattempttoreignitinbyadducingthecriterionof
naturalness.However,beyondtheunhelpfulplatitudethatwhatisnatural(inthissphere)ismind
independent,articulatingwhatnaturalnessis,precisely,hasprovenabridgetoofar.Commonly
suggestedproxiesfornaturalness,suchasscientificauthority,epistemicsuperiority,significance,
andimportance,failtodemarcatewhatisnatural–kindsdelimitedfromanature’seyepointof
view–asopposedtocategoriesthatmerelyreflecthumanpreferences.Totakeanysuchproxyas
determiningtheproperscopeofhyperrealismamountstoamerestipulationofwhichkindsare
“real”.Butthisissimplytoadoptaconventionforrecognizingcertaincategoriesasgenuinekinds.
Thus,onthishornofthedilemma,hyperrealismcollapsesintoconventionalism.
Alternatively,hyperrealistsmaybitethebulletandinterprettheirviewasakindof
maximalismaboutkinds.Onthisinterpretation,movedbyourfailuretocharacterizenaturalnessin
anyhelpfulwayasanindicatorofmindindependence,onesimplyextendsrealismtoanyandall
categoriesthatfacilitatesomemannerofinductivesuccess,orthatwouldunderappropriate
investigativecircumstances.Butthisisincoherentquarealism,forweknowthattheexistenceofat
leastsomeinductivelysuccessfulkindsisnot,infact,mindindependent.Recalltheexampleof
money,theexistenceofwhichassuchdependsonbeliefstotheeffectthatitismoney.Kindrealism
cannothangitshatoninductivesuccessalone,forthiswouldresultinanextensionofrealism,
whichbydefinitionconcernsonlykindswhoseexistenceismindindependent,tokindsthatare
knowntoexistminddependently,amountingtoareductio.
Thisisthefateofrealismaboutkindcategories–dissolutionintoconventionalismonthe
onehand,orincoherenceontheother.Stipulatingproxiesfornaturalnesstoserveasindicatorsof
mindindependencecannotdotheworkthatrealismrequires,fortheyareinherently
anthropocentricandassessedinwaysthatvarycontextually.Refusingtostipulateleavesus
withoutanyrestrictionsonhyperrealismatallbeyondinductivesuccess,whichinaworld
(1991)ideaof‘realpatterns’tosuggestthatdatapatternssatisfyingaconditionofmaximumcompressibility,orcompactness,representkinds.Butagain,varyingdegreesofcompactnessareoptimalfordifferentinductivepurposes,andonemaywonderwhycompactnessshoulddelimitwhatisnatural.
Chakravartty Natural Kind Realism
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putativelyinhabitedbymind-dependentandmind-independentkindsalike,leavesrealists
conflatingtotwo.Skeweredonthisdilemma,naturalkindrealismhasrunitscourse.
6. Remnants of realism: deflationism and mind independence
Inconclusion,letmebrieflycommentontheimplicationsoftheuntenabilityofrealism
aboutkindsspecificallyforrealismmoregenerally.Thisseemsimportantnotleastbecause,inwhat
maynowseemacountervailingspirit,thereisclearlypotentialhereforsignificantredemptionon
thepartofformerkindrealistswhoarenowbereft.Fromamoregeneralrealistperspective,itis
hardlysurprisingthatmanyhavestrainedtoretainsomeformofrealisminrelationtokind
categories,evenwhiletheorizingaboutthemhasrenderedthisprospectincreasinglyfraught.
Conventionalismisitselfcontroversial–theneo-Kantiankernelcanbehardtodigest–andmany
findthisastrongmotivationforclingingtorealismanditspromiseofknowledgeofamind-
independentworld.Thedemiseofkindrealism,however,doesnotentailthatpropositions
regardingkindscannotbetrueorfalseinjustthewaythatrealistscrave:objectively,suchthat
truthvaluesdonotdependonanycontributionsourthinkingmaymaketoconstitutingtheworld;
inotherwords,mindindependently.Thisfollowsfromthesimplefactthatwhilekindsdonot
themselvesexistmindindependently,thetruthmakersofclaimsregardingthemmaywellexistin
justthisway.Itissimplythecasethatkindcategoriesarenotamongthosetruthmakers.Inhopesof
knowledgeofamind-independentworld,manywhohavestruggledtoholdontorealismin
connectionwithkindshavesimplymisappliedthelabel‘realism’.
InadvertingtotruthmakershereIdonotmeantoinvokeanyheavy-dutysemantic
machinery.Considersomeanalogies.Mereologicalnihilismistheviewthatfromthepointofview
ofontology,onlysimples(entitieslackingproperparts)exist.Assumingthattablesare(ultimately)
madeupofsomesuchcomponents,thereare,strictlyspeaking,notables–thoughthereare
certainlycollectionsoftherelevantcomponents‘arrangedtable-wise’.Thisdoesnot,ofcourse,
precludemind-independenttruthsorfalsehoodsregardingtheheightsoftables,theirmasses,and
soon,andthisissoeventhough,onthisview,tablesthemselvesdonotexist.Similarly,oneneed
notbearealistaboutnumberstoholdthat‘2+2=4’isobjectivelytrue.Analogously,onemayhold
thatwhiletherearenomind-independentkindcategories,thereareneverthelessclaimsabout
kindsthataretrueorfalseinamind-independentway.Thiswouldbetosaythattherearemind-
independentaspectsoftheworldinvirtueofwhichclaimsaboutkinds,whichdonotthemselves
existmindindependently,areobjectivelytrueorfalse.Particularsandrelationsofsimilarity;co-
Chakravartty Natural Kind Realism
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occurrences,clusters,correlations,anddistributionsofpropertiesinspacetime;causalrelations,
mechanisms,andstructures…Allofthesethingsmayexistmindindependently,underwritingthe
objectivetruthorfalsityofpropositionsregardingkinds.
Aswehaveseen,someattemptstoclingtorealismaboutkindsendupidentifyingwhatis
(mind-independently)realwithotherthingsinstead,andthisconflationofkindrealismwithother
realismsunderlyingkinddiscourseisnowsowidespreadthatitoftengoesunnoticed.12Obscuring
this,however,onlyservestoobscuretheupshotofmillenniaoftheorizingaboutkinds.Inorder
thattheythemselvesbeentitieswhoseexistenceisamenabletorealism,kindsmustexistmind
independentlyoverandabovetheexistenceofcausalrelations,clustersofproperties,etc.,about
whichonemaybearealistonindependentgrounds.Kindsdonotexistthisway,asanontological
categoryintheirownright,butwemayhaveobjectiveknowledgeofthemnonetheless,andthis
leavesmuchtoarticulateregardingconceptionsofproperties,causation,etc.thatarecentralto
practicesofclassification.Hencetheredemptionforerstwhilekindrealists:mind-independent
knowledgeoftheworldinrelationtokindsmaybeacoherentnotionevenifthemind-independent
existenceofkindsisnot;andthereisimportantworkherestillforrealiststodo.
Thisalsoclarifieshowarejectionofkindrealismmayfitintothelandscapesofbroader
realistdoctrinessuchasscientificrealism.13EarlierImaintainedthattheprincipalconnotationsof
kindconventionalismareconstructivismanddeflationism.Havingjustrevisitedthelatter,letme
concludewiththeformer.Therearedifferentformsofconventionalism.Therelevantnotionof
construction,recall,isthatofmakingacollectionofentitiesintoakindbyrecognizingitassuch;
thisrecognitionisconstitutiveofitsstatusasagenuinecategory.Clearly,therearesomeformsof
constructivismonwhichtherecanbenoknowledgeofanymind-independentfeaturesoftheworld
–inathoroughgoingKantianspirit,onemightholdthatthephenomenalworldweknowisan
inextricablemixofthenoumenalandthemental.Itisnonethelessopentoadifferentsortof
constructivistaboutkindstoholdthatsomeaspectsoftheworldarenotsoconstructed,andinthis
wayvindicateasobjectiveormindindependentthetruthorfalsityofscientific,indigenous,and
everydayclaimsaboutkinds.Isuspectthatformanywhowereoncekindrealistsbutshouldbeno
longer,thiswillberealismenough.
12Thoughnotalways:seeRuphy2010,pp.117-118,onrealismabouttaxonomicfeaturesversuscategories;Bird2018,pp.1398-1407,on‘weak’versus‘strong’realismaboutkinds,theformerassertingonlytheexistenceofnaturaldivisionsandthelatterthatkindsarepartoftheontologyoftheworld;andBrzovic(manuscript),pp.3-7,onrealismaboutwhatcompriseskindsversuskindsthemselves.13Foranaccounthowadeflationary,pluralisticapproachtokindsmaybeintegratedwithscientificrealism,seeChakravartty2007,chapter6.ForaradicallycontrastingviewseeEllis2009,chapter3.
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