Aquinas and the Ship of Theseus: Solving Puzzles About Material Objects CHRISTOPHER M. BROWN Continuum AQUINAS AND THE SHIP OF THESEUS ContinuumStudiesinPhilosophy: SeriesEditor:JamesFieser,UniversityofTennesseeatMartin AndrewFiala,ToleranceandtheEthicalLife ChristopherM.Brown,AquinasandtheShipofTheseus AlexanderW.Hall,ThomasAquinasandJohnDunsScotus RobertDyson,StAugustineofHippo TammyNyden-Bullock,Spinoza’sRadicalCartesianMind DanielWhiting,ThePhilosohyofJohnMcDowell AQUINAS AND THE SHIP OF THESEUS SOLVING PUZZLES ABOUT MATERIAL OBJECTS CHRISTOPHER M. BROWN Continuum TheTowerBuilding,11YorkRoad,LondonSE17NX 15East26thStreet,NewYork,NY10010 &ChristopherM.Brown2005 Allrightsreserved.Nopartofthispublicationmaybereproducedortransmittedin anyformorbyanymeans,electronicormechanical,includingphotocopying,recording, oranyinformationstorageorretrievalsystem,withoutpriorpermissioninwritingfrom thepublishers. 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TypesetbyAarontypeLimited,Easton,Bristol PrintedandboundinGreatBritainbyMPGBooksLtd,Bodmin,Cornwall CONTENTS Preface vii ListofAbbreviations x 1 TheProblemofMaterialConstitution(PMC) 1 Common-senseintuitionsaboutcompoundmaterialobjects 2 TheShipofTheseusandthePMC 4 SolvingthePMC:aglanceatthecontemporaryapproaches 5 2 ThreeContemporaryApproachestoSolvingthePMC 16 LynneRudderBaker’sconstitutionview 16 PetervanInwagenoncomposition,eliminativismandthePMC 24 TheZimmermanArgument 32 3 AquinasonMaterialSubstances 48 Aquinasonthenatureofsubstances 48 Aquinasonthenatureofmaterialsubstances 57 Aquinasontheextensionof‘materialsubstance’ 59 4 AquinasontheCompositionofMaterialObjects 68 Aquinasonthedi¡erentwaysthatmaterialobjectsarecomposed 68 Aquinasonthecompositionofmaterialsubstances 71 Aquinasonartefactsandcomposition 98 5 AquinasonIdentity,IndividuationandMaterialComposition 113 Aquinasontheidentityofmaterialsubstancesthroughtime andchange 113 Aquinasontheindividuationofmaterialsubstances 124 Aquinasontheidentityandindividuationofartefacts 130 6 AquinasandtheProblemofMaterialConstitution 144 TheShipofTheseuspuzzle 144 TheDebtor’sParadox 150 TheGrowingArgument 155 vi Contents ThePuzzleof TibblestheCat 157 TheLumpl/Goliathpuzzle 160 TheadvantageofaThomisticapproachtothePMC 162 7 AnsweringObjectionstotheThomisticApproachtothePMC 168 AquinasandBaker:theadvantagesofamitigatedontological pluralism 168 AquinasandVanInwagen:defendingtherealityofnon-living materialsubstances 172 TheZimmermanArgument:aThomisticresponse 176 SelectBibliography 183 Index 189 PREFACE Inthelasttwenty-¢veyearsanumberofphilosophershavearguedthatclassi- calpuzzlesaboutmaterialobjectssuchastheShipofTheseusshowthatour common-senseintuitionsaboutcompoundmaterialobjectsarelogicallyincom- patiblewithoneanother.Itseemstothesephilosophersthatwehavetoeither give up one of our common beliefs about material objects or else give up reasoningaboutmaterialobjectsaltogether.Althoughthereareanumberof solutionstoShipofTheseus-stylepuzzlesthathavegarneredsupportamong contemporaryanalyticphilosophers,virtuallyallofthesesolutionsarguefor the rejection of a common-sense intuition about material objects. Whatever else may be said therefore in defence of these particular solutions, they all entailrevisingourcommon-senseunderstandingofamaterialobject. One way of approaching the project of solving puzzles about material objects involves ¢rst re-examining some of our own fairly entrenched meta- physicalassumptionsaboutsuchobjects.Thisre-examinationprojectisitself ably facilitated by comparing contemporary views on material objects with thoseofagreatmetaphysicianfromthepast,someonewhomaynotshareall of our contemporary philosophical predilections. Indeed, some of Thomas Aquinas’s views on the composition of material substances are at variance with metaphysical assumptions commonly presupposed by contemporary analytic philosophers and Aquinas’s views suggest some interestingly novel waysofhandlingclassicalandcontemporarypuzzlesaboutmaterialobjects. In this work I propose that Aquinas’s metaphysic of material objects (or whatissometimesreferredtoashis‘naturalphilosophy’)showsthatitispos- sible to solve Ship of Theseus-style puzzles and still hold on to all of our common-sense intuitions about material objects. Although Aquinas never explicitly tackles problems such as the Ship of Theseus puzzle ^ probably becauseAristotledoesnothavemuchtosayaboutsuchmatters ^ whatAqui- nasdoeshavetosayaboutsubstances,compositionandidentityallowsoneto construct a set of Thomistic solutions to the famous puzzles about material objects. These Thomistic solutions do not entail the falsity of any of our common-senseintuitionsaboutmaterialobjects. IarguehereinseveralstagesfortherelevancyofAquinas’sthoughtforthe solving of puzzles about material objects. The ¢rst two chapters show how contemporary analytic philosophers approach philosophical problems havingtodowiththenatureofmaterialobjects.Morespeci¢cally,inthe¢rst viii Preface chapterIbothexplainhowcertaincommon-senseintuitionsaboutcompound materialobjectsaresupposedtoleadtoproblemsinthe¢rstplaceandIo¡era surveyofthemostimportantcontemporarysolutionstothoseproblems.The secondchaptertakesadetailedlookatsomeargumentsaboutmaterialobjects put forward by three important contemporary metaphysicians: Peter van Inwagen, Lynne Rudder Baker and Dean Zimmerman. Having clari¢ed how contemporary analytic philosophers approach the classical puzzles about material objects, I o¡er my own exegesis of Aquinas’s metaphysic of material objects in the next several chapters. The third chapter introduces Aquinas’smetaphysicofmaterialobjectsthroughanexaminationofaconcept crucialtohisphilosophicalenterprise,theconceptofmaterialsubstance.The fourth chapter discusses Aquinas’s views on material composition and part- hood.The¢fth chapterexplainsAquinas’sviewson theidentity and indivi- duationofmaterialobjectsthroughtimeandchange.The¢naltwochapters oftheworkbringmyexegesisofAquinas’smetaphysicofmaterialobjectsto bearonpuzzlesaboutmaterialobjects.Inparticular,thesixthchaptershows howAquinas’sviewsonmaterialcompositionandidentityallowhimtosolve classicalandcontemporarypuzzlesaboutmaterialobjectsinwaysthatpre- serve our common-sense intuitions about material objects. Finally, the seventhchapterdefendstheseThomisticsolutionstopuzzlesaboutmaterial objectsagainstsomepossibleobjections. I would like to thank those people who have had a hand, in one way or another,inhelpingmetocompletethisbookonAquinas’smetaphysicofmate- rialobjects.Thankstooneofmy¢rstphilosopherteachers,ArvinVos,who¢rst sparkedmyinterestinAquinas’sthought.Thefollowingpeopleprovidedhelp- fulcommentseitheronportionsofthemanuscriptoronpapersthatareances- tors to it: Adiel Brasov, Je¡ Brower, Merry Brown, Chris Calloway, John Claiborne, Bryan Cross, Darin Davis, William Eaton, Jason Eberl, Miguel Endara, James Fieser, Alicia Finch, Norman Lillegard, Scott MacDonald, Steven Napier, Robert Pasnau, William Rehg, Karl Schudt, Kevin Timpe, JoshuaThurowandChristinaVanDyke.FatherTheodoreVitaliandColleen McCluskey read and commented upon an early version of the entire manu- script.Io¡erspecialthankstoEleonoreStump.Shenotonlygavemeextensive commentsonanumberofearlydraftsoftheentiremanuscriptbuthasalsobeen agreatmentortome,bothprofessionallyandscholastically.Iwouldliketo thanktheentiredepartmentofPhilosophyatSaintLouisUniversityforpro- viding such an intellectually fertile and caring place in which to receive a graduatephilosophicaleducation.Also,severalgrantsthatIreceivedwhilea studentatSaintLouisUniversitymadeitpossibleformetoworkonpapers (and a dissertation) that are ancestors to this book, namely, a 2000^2001 SLU2000fellowshipanda2001^2002dissertationfellowship.Thanksalsoto mycolleaguesinthedepartmentofHistoryandPhilosophyattheUniversity Preface ix ofTennesseeatMartinforassistanceandencouragementduringthetimethat Iwasworkingonthe¢nalrevisionsofthemanuscript.InthisregardIwould especially like to thank Jim Fieser, Norman Lillegard, David Co¡ey and DonnaCooperGraves. IreservethegreatestthanksforGodandmyfamily.Forallofhersupport andlovethroughtheyears,IthankmywifeMerryElizabeth.Merryisoneof the most multi-faceted persons I know, a wonderful wife, mother, teacher ^ andphilosopher.Icouldn’thavedoneanyofwhatIattempttodointhiswork without her patient love and support. Thank you to my parents, Noel and Patricia Brown, my parents-in-law Ed and Susan Hill, and my siblings NoelleandBrandonforalwaysbeingthere.Finally,Iwouldliketothankmy sonsJudahChristopherandLeopoldEdwardsimplyforbeing.Idedicatethis booktothem.