Laws and Powers in the Frame of Nature Stathis Psillos 1 Till a philosopher, at last, arose, who seems, from the happiest reasoning, to have also determined the laws and forces, by which the revolutions of the planets are governed and directed. David Hume (First Enquiry, section I, 14) 1. Introduction Within the Aristotelian framework of natural philosophy, which was dominant until the emergence of the mechanical philosophy, activity, motion and change in nature were taken to be grounded in powerful substances. From the seventeenth century on, this view started to recede in favour of a conception of nature as governed by general laws of nature and of motion in particular. This new conception was introduced, almost single-handedly, by Rene Descartes but it spread quickly. 2 Part of the motivation was a thorough critique of the widespread view that, when it comes to natural bodies, they possess active and passive powers in virtue of which they interact with each other. Natural powers were taken to be necessity-enforcers in that they were, in and of themselves, principles of necessitation: given the power of X to Φ, X must Φ when the appropriate circumstances arise. Hence, powers were regularity–enforcers: they accounted for the regularity there is in the world. The new conception of laws emerged as an alternative to powers. Corporeal substances were widely taken to be passive and inert. Hence, activity, motion and change could not arise from within a powerful matter. They had to be imposed on matter from without and this meant that there was need for new principles of connection, viz., principles which determined the ways pieces of matter move and collide with each other. Laws of nature were broadly taken to be the required principles of connection. This very move was itself based on a thorough reconceptualisation of the very idea of natural law. The notion was widely applicable to rational beings only, since the dominant thought was that only rational beings can obey the law. After Descartes, the concept of law was widely taken to apply to all beings; and in particular to passive corporeal substances. 3 The new principles of connection—laws of nature—retained a key feature of the powers-based account of activity in nature, viz., necessity. They were meant to hold by necessity, thought what kind of necessity this is was very much in dispute. They were also meant to necessitate the behaviour of things: things had 1 Dept of Philosophy and History of Science, University of Athens, Greece; and Rotman Institute of Philosophy, University of Western Ontario, Canada. [email protected] 2 There is important historical work concerning the origins of the concept of law of nature. For a thorough discussion and support of the claim that Descartes should be credited with initiating the modern conception, see Henry (2004). 3 Hobbes resisted this trend and refrained from extending natural laws to non-rational beings. For more on this see Goudarouli & Psillos (forthcoming).
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
LawsandPowersintheFrameofNature
StathisPsillos1
Tillaphilosopher,atlast,arose,whoseems,fromthehappiestreasoning,tohavealsodeterminedthelawsandforces,bywhichtherevolutionsoftheplanetsaregovernedanddirected.DavidHume(FirstEnquiry,sectionI,14)
1.IntroductionWithintheAristotelianframeworkofnaturalphilosophy,whichwasdominantuntiltheemergenceofthemechanicalphilosophy,activity,motionandchangeinnatureweretakentobegroundedinpowerfulsubstances.Fromtheseventeenthcenturyon,thisviewstartedtorecedeinfavourofaconceptionofnatureasgovernedbygenerallawsofnatureandofmotioninparticular.Thisnewconceptionwasintroduced,almostsingle-handedly,byReneDescartesbutitspreadquickly.2Partofthemotivationwasathoroughcritiqueofthewidespreadviewthat,whenitcomestonaturalbodies,theypossessactiveandpassivepowersinvirtueofwhichtheyinteractwitheachother.Naturalpowersweretakentobenecessity-enforcersinthattheywere,inandofthemselves,principlesofnecessitation:giventhepowerofXtoΦ,XmustΦwhentheappropriatecircumstancesarise.Hence,powerswereregularity–enforcers:theyaccountedfortheregularitythereisintheworld. Thenewconceptionoflawsemergedasanalternativetopowers.Corporealsubstanceswerewidelytakentobepassiveandinert.Hence,activity,motionandchangecouldnotarisefromwithinapowerfulmatter.Theyhadtobeimposedonmatterfromwithoutandthismeantthattherewasneedfornewprinciplesofconnection,viz.,principleswhichdeterminedthewayspiecesofmattermoveandcollidewitheachother.Lawsofnaturewerebroadlytakentobetherequiredprinciplesofconnection.Thisverymovewasitselfbasedonathoroughreconceptualisationoftheveryideaofnaturallaw.Thenotionwaswidelyapplicabletorationalbeingsonly,sincethedominantthoughtwasthatonlyrationalbeingscanobeythelaw.AfterDescartes,theconceptoflawwaswidelytakentoapplytoallbeings;andinparticulartopassivecorporealsubstances.3 Thenewprinciplesofconnection—lawsofnature—retainedakeyfeatureofthepowers-basedaccountofactivityinnature,viz.,necessity.Theyweremeanttoholdbynecessity,thoughtwhatkindofnecessitythisiswasverymuchindispute.Theywerealsomeanttonecessitatethebehaviourofthings:thingshad
1 DeptofPhilosophyandHistoryofScience,UniversityofAthens,Greece;andRotmanInstituteofPhilosophy,UniversityofWesternOntario,Canada.psillos@phs.uoa.gr2Thereisimportanthistoricalworkconcerningtheoriginsoftheconceptoflawofnature.ForathoroughdiscussionandsupportoftheclaimthatDescartesshouldbecreditedwithinitiatingthemodernconception,seeHenry(2004).3Hobbesresistedthistrendandrefrainedfromextendingnaturallawstonon-rationalbeings.FormoreonthisseeGoudarouli&Psillos(forthcoming).
2
toobeythelawsthatgovernedtheirbehaviour.Butifthereisnopowerinmatter,howdoesmatteractonmatter?Broadlyspeaking,therearetwooptionsavailable,giventhepassivityofmatter.ThefirstisthatmatterexistsbutGodistheonlymotiveforce(thisisthelinefollowedbyMalebrancheandcametobeknownasOccasionalism).Theotheristodenytheexistenceofmatteraltogether(sincethereisnothingforittodo)andtoclaimthatGodisthedirectcauseofallideasinminds(thisleadstoBerkeley’sidealism).Onbothoptions,lawsplayakeyrole:theyreplacepowersandprovidethemissingconnectionsbetweendistinctexistences.Theaimofthispaperistorevisitthemajorargumentsoftheseventeenth
centurydebateconcerninglawsandpowers.Itsprimarypointsaretwo.First,thoughthedominantconceptionofnaturewassuchthattherewasnoroomforpowerinbodies,theveryideathatlawsgovernthebehaviourof(bitsof)matterinmotionbroughtwithitthefollowingissue,whichcameundersharpfocusintheworkofLeibniz:howpossiblycanpassivematter,devoidofpower,obeylaws?ThoughLeibniz’sanswerwastore-introducepowers,tworadicallydifferentconceptualisationsoftherelationbetweenlawsandpowersbecameavailableafterhim.Humedeniedpowersaltogether,whereasNewtonthoughtthattointroduceapoweristointroducealaw.Thesecondmainpointwillbethatthoughlawsweremeanttoreplacepowers,therealdilemmaendedupbeingnotlawsvspowers,butrathernecessityvsnon-necessityinnature.Toexploit,anexpressionusedbyNewton,thequestionwas:whatistheplaceofnecessityintheframeofnature?2.AgainstLaws;AgainstPowersForMediaevalthinkers,naturalagencywasfundamentalandexplicableintermsofthepowersofthenaturalagentsthemselves.God,however,wastakentobetheauthoroftheorderoftheworldanditsorderingtoanend.So,thoughthereisorderintheworldandinthissenseGodistheDivineorder-maker,Hedoesnotpositlawsofnatureoverandabovetheactivenaturesofnaturalthings.Insofarasthereistalkof‘lawsofnature’,thisisametaphoricalextensionoftheconceptfromtherealmoffreeagentstonature.4 OnecanseethiskindofapproachveryclearlyintheworkofthelateMedievalthinkerFranciscoSuarez.AccordingtoThomasAquinas(Summa,I-IIq.90art.1):“Law(lex)isacertainruleandmeasureinaccordancewithwhichoneisinducedtoactorisrestrainedfromacting”(Suarez1612,7)Thusput,Suareznotes,thedefinitionoflawis“toobroadandgeneral”preciselybecauseitallowsthatitisapplicabletonon-sentientbeings,since“everythinghasitsownruleandmeasure,inaccordancewithwhichitoperatesandisinducedtoactorinrestrainedtherefrom”.ForSuarez,however,laws,strictlyspeaking,requirerationalagency.Alawissomethingthathastobe(andcanbe)obeyed(executed)andthiscanonlybesatisfiedbyrationalcreatures.Inthissense,theclaimthatnon-sentientbeingsobeylawswouldamounttotheclaimthattheyactaccordingtothetheirnaturalpowers.Indeed,insofarasthismetaphoricalsenseoflawisused,itcanonlyrefertotheorderlyactionofnaturalbodies“inaccordancewiththeinclinationsimpartedtothembytheAuthorofNature”(1944,22).Seenthatway,talkofnaturallawsistalkaboutnaturalpowers.It
4ThispointhasbeenrecentlystressedbyMarilynMcCordAdams(2013).
3
capturesthenaturalnecessitythereisinnatureanditistothisnaturalnecessitythatcanbe“metaphoricallygiventhenameoflaw”(ibid.).Note,inaddition,thatiftalkoflawsofnatureistalkaboutpowers,thereare
asmany‘lawsofnature’astherearepowers—alawforeachpowerinnature.Lawsofnature,then,playnorolewhatsoeverasunifiers.Still,ifthismetaphoricaluseismade,theremustbealaw-makerwhogovernsthethingsthat‘obeythelaw’.AsSuarezputit,insofarasnon-rationalbeingsaresaidtoobeyalaw,theyare“inneedofasuperiorgoverningmind”(…)“andthusfromeverystandpoint,lawmustberelatedtomind”.Insum,then,talkoflawsismetaphoricalanditspropercontentconcernsnaturalnecessitieswhicharegroundedinthenaturalinclinationsofthingsimpartedonthembythelaw-maker.Theemergenceofmechanicalnaturalphilosophyintheseventeenthcentury
broughtwithitawaragainst(natural)powers.Quaasuigeneriscategorythatexplainsorgroundsmotionandchangeinnature,powercameunderheavyfire.Herearethemainargumentsagainstpowers.5Theconnectionproblem:howarepowersconnected?HowisitthatXhavingthepowertoΦandYhavingthepowertobeΦ-ed(twodistinctexistences)interacttogiverisetoaneffect?AccordingtoDescartes,thepowerofXtoΦisnotsuigenerisbutshouldbeunderstoodintermsofmatterinmotion.AllthereistoexplainhowXactsonYisactionbycontactofthepartsofXonthepartsofY.InhisLeMonde,DescartesobjectedtothemedievalAristotelianviewthatfirehasthe(suigeneris)powertoburnwoodthatallthereistotheactionoffireonwoodcanandshouldbeunderstoodintermsoftheviolentandincessantmotionofthepartsoffire:
When[fire]burnswoodorothersimilarmaterialwecanseewithoureyesthatitmovesthesmallpartsofthewood,separatingthemfromoneanother,therebytransformingthefinerpartsintofire,air,andsmoke,andleavingthelargerpartsasashes.Someoneelsemayifhewishesimaginethe‘form’offire,the‘quality’ofheat,andthe‘action’ofburningtobeverydifferentthingsinthewood.Formyownpart,IamafraidofgoingastrayifIsupposetheretobeinthewoodanythingmorethanwhatIseemustnecessarilybethere,soIamsatisfiedtoconfinemyselftoconceivingthemotionofitsparts.Foryoumayposit‘fire’and‘heat’inthewood,andmakeitburnasmuchasyouplease:butifyoudonotsupposeinadditionthatsomeofitspartsmoveaboutanddetachthemselvesfromtheirneighbours,Icannotimagineitundergoinganyalterationorchange(1998,6).
Ineffect,Descartes’spointisthatevenifpowerswereposited,theywouldfailtoexplain,inandofthemselves,changeinnature;theproperexplanationwouldrequirereferencetotheactionofthepartsofthebodiesthatbearthe‘activepower’onthepartsofthebodiesthatbearthe‘passivepower’.Butthisverymovewouldmakepowersredundant,sincealltheactionwouldbeduetothemotionofthepartsofbodies. Thiskindofargumentagainstpowersisdirectedprimarilyagainstviewingpowersassuigeneris.Powerisnotaspecifickindofcauseofmotion/change,distinctforeachkindofmotion/change.Allmotion/changeinnatureshouldbeunderstoodasbeingofthesamekind,viz.,theresultofactionbycontactbetweenthepartsofmatter.Objectingtotheviewthatpowersaresuigeneris5Forfurtherinsightfuldiscussion,seeOtt(2009,chapter5).
4
principlesofmotion,Descartesnoted:“ThePhilosophersalsopositmanymotionswhichtheybelievecanoccurwithoutanybody’schangingplace,suchasthosetheycallmotusadformam,motusadcalorem,motusadquantitatem(motionwithrespecttoform,motionwithrespecttoheat,motionwithrespecttoquantity)andcountlessothers”(1998,26).Butheadded:“Iknowofnomotionotherthanthatwhichiseasiertoconceiveofthanthelinesofgeometers,bywhichbodiespassfromoneplacetoanotherandsuccessivelyoccupyallthespacesinbetween”(1998,27).Hence,allmotionshouldbeunderstoodunivocallyaslocalmotion,andifasenseofpowerisstilloperativeitcanatbestbeseenasthepowerofmattertobemoved(mobility). ForDescartes,then,therearenosui-generispowersinnature.Tounderstandallchangeinnatureitisenoughtoconceivethemotionsofthepartsofmatter—subjecttouniversallaws,asweshallseeinthenextsection.Speakingagainagainsttheallegedsuigenerispoweroffiretoburn,Descartes(1998,8)noted:
Onceweappreciatethatthepartsoftheflamemoveinthisway,andthattounderstandhowtheflamehasthepowertoconsumethewoodandtoburnit,itisenoughtoconceiveoftheirmotions,Iaskyoutoconsiderwhetherthisisnotalsosufficientforustounderstandhowtheflameprovidesuswithheatandlight.Forifthisisthecase,theflamewillneedpossessnootherquality,andweshallbeabletosaythatitisthismotionalonethatiscallednow‘heat’andnow‘light’,accordingtothedifferenteffectsitproduces.
Theoccultnessproblem:Thisisaversionoftheconnectionproblemabove.Butitisworthtreatingitseparatelybecausetheemphasisisshiftedtotheclaimthat,inprinciple,thereisnounderstandingofhowapowerbringsaboutitseffect.InalettertoRegiusinJanuary1642,Descartes(1991,208-9)noted:
Butnonaturalactionatallcanbeexplainedbythesesubstantialforms,sincetheirdefendersadmitthattheyareoccultandthattheydonotunderstandthemthemselves.Iftheysaythatsomeactionproceedsfromasubstantialform,itisasiftheysaidthatitproceedsfromsomethingtheydonotunderstand;whichexplainsnothing.Sotheseformsarenottobeintroducedtoexplainthecausesofnaturalactions.
Wemaycallthis,theexplanatoryimpotenceargument.Substantialformswereindividuatingprinciplesthatoncejoinedwithspecificparcelsofprimemattermadethemintosubstanceswithaspecificcausalprofile.So,forinstance,thesubstantialformsofhardbodieswasdifferentfromthesubstantialformoffluidbodiesandthisprimitivedifferenceexplainedtheirdifferentpowers.ButforDescartesnoexplanationofthedifferenceistherebyachieved:thedifferenceissimplypositedasaprimitivefact.Forhim,theonlydifferencebetweenhardbodiesandfluidbodiesis“thatthepartsoftheonecanbeseparatedfromthewholemuchmoreeasilythanthoseoftheother”(1998,10).Thisissupposedtoamounttoagenuineexplanationofwhytherearetwodistinctkindsofqualities—hardnessandfluidity—thedifferencebeinggroundedinthemicro-partsofbodiesandtheirmotions.Insteadoftakingthesequalitiesasprimitive,Descartesexplainsthembyshowingthattheyaredifferentspeciesofmotionoftheparticlesofmatter.Hereishowheputit:
Ifyoufinditstrangethat,inexplainingtheseelements,Idonotusethequalitiescalled‘heat’,‘cold’,‘moistness’,and‘dryness’,asthePhilosophersdo,Ishallsaythatthesequalitiesappeartometobethemselvesinneedofexplanation.Indeed,unlessIammistaken,notonlythesefourqualitiesbutallothersaswell,includingeventheformsof
5
inanimatebodies,canbeexplainedwithouttheneedtosupposeanythingintheirmatterotherthanmotion,size,shape,andarrangementofitsparts(1998,18).
Thedirectednessproblem:howcanaphysicalqualitybedirectedtoanother?Thiswas,inmanyways,themorepuzzlingfeatureofpowers.Medieval-Aristotelianpowerswereendowedwithesse-ad.Thiswassupposedtoshowhow“onethingreceivessomethingfromanotherorconfersitupontheother”(Aquinas)withoutthequalitiesofeachthingbeingsharedbytheother.Butthepuzzlewaspreciselyhowaqualitycanbeintrinsictoasubjectand‘bear’onanother.ForDescartes,thisrelatednesscanonlybeafeatureofmindsandtheircontent:onlymindscanbedirectedtowardsanything.Hence,eithermattershouldbeendowedwithmindsortherecanbenosuchthinginmatteras‘beingdirectedtoaneffect’.ThefirsthornispreciselytheoneDescartesdismissedbywhatcametobeknownas‘thelittlesoulsargument’.InalettertoMersenne,(26April1643)henoted:
Idonotsupposethereareinnatureanyrealqualities,whichareattachedtosubstances,like somany little souls to their bodies, and which are separable from them by divinepower. Motion, and all the other modifications of substance which are called qualities,havenogreaterreality,inmyview,thaniscommonlyattributedbyphilosopherstoshape,whichtheycallonlyamodeandnotarealquality(1991,216).
Thereferencehereistothemedievalideathatqualitiescanexistindependentlyofsubstances.Butwhat’sinterestingisthatDescartestakesitthatthesequalitieswereendowedwithdirectednessasiftheyweresoul-likeentities.AsheexplainedinalettertoPrincessElizabeth,21May1643,realqualitieswereconceivedbymeansofnotionsthatwereused“forthepurposeofknowingthesoul”(1991,219).Gravity,oneofDescartes’sfavouriteexamples,isacaseinpoint.Descartesnotedthatinsteadoftakingtheviewthatheavinessisakindofmotionwhichis“producedbyarealcontactbetweentwosurfaces”(1991,219),hismedievalpredecessors,startingfromthe“innerexperience”ofhowthesouloperatesonbodies,tookitthatheavinessisarealquality“ofwhichallweknowisthatithasthepowertomovethebodythatpossessesittowardsthecentreoftheearth”(1991,219),therebywronglyattributingtoitsoul-likeattributes.Speakingcriticallyofhisformerselfinthesixthsetofreplieshenotedthathetoousedtoascribetogravitysomekindofdirectedpowertocarrybodiestowardsthecentreoftheearth“asifithadsomeknowledgeofthecentre”.Buthechangedhismindwhenherealisedthatthiswastantamounttoapplyingmind-likepropertiestogravity;forthisdirectedness“surelycouldnothappenwithoutknowledge,andtherecanbenoknowledgeexceptinamind”(1984,298).Themotiveforceproblem:Howcanabodymoveitselforanotherbody?ThisquestionwasthrownintosharpreliefbyNicolasMalebranchewhoconcludedthattheonlymotivepoweris(in)God.AccordingtoawidelyacceptedaccountofGod’saction,Godcontinuouslyannihilatesandre-createseverythingthereis.WhenGodwillsabodyAtocometoexistence,hewillsittobeinaspecificspaceaataspecifictimet.How,then,Malebrancheasks,canthebodyAmovefrompointatoanotherpointballbyitself?Orhowcanitbemovedbythe‘power’ofanotherbodyB?Ineithercase(self-motionormotion-by-other)therequired
6
powerwould‘supersede’thepowerofGod,whowilledbodyAtobeinpointa.SincenothingcansupersedeGod’spower,onlyGodhasthepowertomoveabody.Malebrancheconcludedthat“thereisacontradictioninsayingthatonebodycanmoveanother”,since“nopower,howevervastitmaybeimaginedtobe,cansurpassorevenequalthepowerofGod”;“nopowercantransport[abody]whitherGoddoesnottransportit,norfixorkeepitwhereGoddoesnotfixorkeepit,ifitisGodalonewhoadaptstheefficacyofHisactionstotheineffectiveactionsofHiscreations”(DialoguesonMetaphysics7,X;1923,189).Argumentssuchastheabovecastconsiderabledoubtontheideathatmatter
ispowerful.Butifthereisnopowerinmatter,whatoptionsareavailable?Lawsofnaturereplacedpowersasprinciplesofconnectionbetweendistinctexistences.Butlawsdidnotreplacenecessity.Instead,theycapturedthenecessitythatwastakentobegroundedinpowers.Buthowdolawsacquiretheirnecessityandwhatkindofnecessityisthis?63.CartesianLawsInDescartes’sPrincipia,whichappearedin1644,Godistheprimarycauseofallmotion.Butlawsofnaturebecomethemselvestheparticularcauses“bywhichindividualpartsofmatteracquiremovementswhichtheydidnotpreviouslyhave”(PartII,36;1982,58).Theyaccountforchangesofstatesofmotionofbodies:“therulesorlawsofnature(…)arethesecondaryandparticularcausesofthediversemovementswhichwenoticeinindividualbodies”(PartII,37;1982,59).Butwhatdoesthatmean?Howcanlawsbesecondarycauses?ToanswerthisquestionletusfirsttakealookatDescartes’sthreelawsof
motion.IntheCartesianpictureofthings,Godcreatedmatterinmotionandrest“andnowmaintainsinthesumtotalofmatter,byHisnormalparticipation,thesamequantityofmotionandrestasHeplacedinitatthattime”(PartII,36;1982,58).Throughouthiswork,thisisafundamentalidea:theconservationofthetotalquantityofmotionplacedinnaturebyGodinitially.Thisisnotalaw—itisagoverningprinciple.ItfollowsdirectlyfromtheimmutabilityofGod.Infact,itcanbesaidthatthisPrincipleofConservationoftheQuantityofMotion(PCQM)issimplyafacetofGod.7NotethatGodmightnothavechosentoputmatterinmotion.Hence,PCQMdependsonGod’sWillinthesensethatHewilledtosetmatterinmotion.Butgiventhisvolition,PCQMismetaphysicallynecessary.Godbeingimmutable,PCQMhastoholdisallpossibleworldsinwhichmatterisinmotion. ThethreefundamentallawsofnaturearegroundedinPCQM,thatisintheimmutabilityofGod.Theyarepartofthefabricoftheworld.Givenhiswilltosetmatterinmotion,PCQMandthefundamentallawsareaconstitutivepartofnature:theyfollowfromhisimmutability.Everythingthathappensinnatureissubjecttothem.Motion,inotherwords,isregulatedbyGodvialaws,subjecttoanoverallPCQM.Descartessays:“becauseGodmovedthepartsofmatterin
6ForlackofspaceIdonotdiscussDescartes’saccountoflawsandpowerinLeMonde.SufficeittosaythatitisarguablethatDescarteschangedhispositioninmovingfromLeMondetohismatureworkPrincipia.Brieflyput,inLeMondelawsplayacausalrole,butmatteriscausallyactivetoo.Forfurtherdiscussion,andforwhatItakeittobetherightaccountofthetransitionfromLeMondetoPrincipia,seeOtt(2009,55ff).7ForsomesimilarthoughtsseeGarber(2013).
7
diversewayswhenHefirstcreatedthem,andstillmaintainsallthismatterexactlyasitwasatitscreation,andsubjecttothesamelawasatthattime;Healsoalwaysmaintainsinitanequalquantityofmotion”(PartII,36;1982,58).Thencomethethreelaws. Thefirstlaw:“thateachthing,asfarasisinitspower,alwaysremainsinthesamestate;andthatconsequently,whenitisoncemoved,italwayscontinuestomove”(PartII,37;1982,59). ForDescartesmotionandrest(lackofmotion)aretwodistinctstatesofmatter.Rest(changeofstateofmotiontoRest)requiresexternalagency(collision).Nothingmovesfrombeinginmotiontobeinginlackofmotion(Rest)“byvirtueofitsownnature”becausethiswouldmeanthatitwouldmove“towarditsoppositeoritsowndestruction”.Thisisthejustificationofthefirstlaw.Descartesnotesthatthislaw“resultsfromtheimmutabilityandsimplicityoftheoperationbywhichGodmaintainsmovementinmatter”(PartII,39;1982,60).What’simportanttoaddhereisthatDescartesexplicitlydeniesthatbodiesareendowedwithtendenciesorcapacitiestochangetheirstateofmotion“byvirtueoftheirownnature”(PartII,37;1982,59).Thesecondlaw:“thatallmovementis,ofitself,alongstraightlines;and
consequently,bodieswhicharemovinginacirclealwaystendtomoveawayfromthecenterofthecirclewhichtheyaredescribing”(PartII,39;1982,60).Thislawcapturestheideathatcircularmotionis“forced”or“constrained
motion”:itisdeviationfromthestraightpathduetotheencounterofotherbodiesorduetotherigidconnectionsamongthepartsofabody(asinthemotionofawheel).Descartes’sjustificationisbaseddirectlyontheimmutabilityofGodandthesimplicityofhisoperations.Thislawtoo,hesays,“liketheprecedingone,resultsfromtheimmutabilityandsimplicityoftheoperationbywhichGodmaintainsmovementinmatter”(PartII,39;1982,60).TheappealtoimmutabilityofGodisessentialbecauseGodmaintainsmotioninmatterasitisateverysinglemoment.Hemaintainsmovementinmatter“preciselyasitisattheverymomentatwhichHeismaintainingit,andnotasitmayperhapshavebeenatsomeearliertime”(PartII,39;1982,60).Butthemotionateachinstant(ormoment)isalongastraightline.Though“nomovementisaccomplishedinaninstant”,Descartesconsidersitobviousthat“everymovingbody,atanygivenmomentinthecourseofitsmovement,isinclinedtocontinuethatmovementinsomedirectioninastraightline,andneverinacurvedone”(PartII,39;1982,60).Simplicity,however,isimportant,becausemotionalongastraightlineissimplerthancurvilinearmotion.Fromthislaw,Descartessays,itfollowsthat“anybodywhichismovinginacircleconstantlytendstomove[directly]awayfromthecenterofthecirclewhichitisdescribing”.Hence,thecentrifugaltendencyofarotatingstoneintheslingisgroundedinthesecondlaw. Thethirdlaw:“thatabody,uponcomingincontactwithastrongerone,losesnoneofitsmotion;butthat,uponcomingincontactwithaweakerone,itlosesasmuchasittransferstothatweakerbody”. DescartesprovesthethirdlawbyappealingtotheimmutabilityofGod.Inthecreation,Godgavemotiontoparticlesandcausedsomeofthemtocollidewithother.Becauseheisimmutable,heconservesmotioninparticles;hencethetotalquantityofmotion,includingthiswhichistransferredfromoneparticletoanother,remainsthesame:“innowmaintainingtheworldbythesameactionandwiththesamelawswithwhichHecreatedit,Heconservesmotion;not
8
alwayscontainedinthesamepartsofmatter,buttransferredfromsomepartstoothersdependingonthewaysinwhichtheycomeincontact”(PartII,42;1982,62).Howthenarelawsthe“secondaryandparticularcausesofthediverse
movementswhichwenoticeinindividualbodies”(PartII,37;1982,59)?Giventhatbodiesweresetinvariousstatesofmotioninthebeginning,lawscause(i.e.,determine)theirsubsequentstates.WhydoesXmoveinastraightline?Becauseitisalawthatitmustkeepmoving(itwon’tchangeitsstateofmotion)untilsomethingstopsit(Firstlaw).Inthissense,thelawisacauseofthemovementofX,sinceitdictates(determines)itsmotion.Similarly,whydoesXstopmoving?(orwhydoesXchangeitsstateofmotion?)BecauseitisalawthatXmustchangeitsstateofmotionifitcollideswithanotherbodyY.Hence,changeofthestateofmotionofXisalaw-governedcollisionwithanotherbodyY(Thirdlaw).Finally,whydoesXmoveinacurvedpath?Notbecause“itisinclinedtoanycircularmovement”;butbecauseitisalawthatmotionalongcurvedpathABisforcedmotion,thatisitconsistsinadeviationfromthestraightline(Secondlaw).ItisstrikingthatinthePrincipia,thereisnoreferencetothedispositionsof
matterascausesofthemotionofthebodiesalongsidethelawsofnature.8Tobesure,Descartesdoestalkaboutaffections,buthestatesclearlythatalldispositions[omniumaffectionum]ofmatterariseoutofthemovementsofitsparts;hencetherearenosuigeneris(non-mechanical)dispositions(cf.PartII,23;(1982,50).Heexplicitlystatesthatwhenheusesexpressionssuchas“striving[conatus]ofinanimateobjectstowardmotion”,hedoesnotattributeanythoughtorintentiontothem;hesimplymeans“thattheyaresosituated,andsourgedtomove[admotumincitatos],thattheywillinfactrecedeiftheyarenotrestrainedbyanyothercause”(partIII,56;1982,112).AndinIV.199,hesumsuphisviewbysayingthatallnaturalphenomenaare“nothingotherthan,certaindispositions[dispositiones]ofsize,figure,andmotion{ofbodies}”(1982,282).SothereisnoreasontothinkthatforDescartesthereferencestodispositions,affectionsandthelikeinthePrincipiaarenothingotherthanthe(passive)mechanicalqualitiesofthecorpusclesofmatter.InfactinPrincipia,forcesandgenericpowersofmatterarefullyreplacedby
laws.9InacharacteristicpassageinII.43,Descartesstatesthat“theforceofeachbodytodriveortoresistconsists”inthebody’sobeyingthefirstlawofmotion—8InLeMondeDescartesnotesthatthoughwhenitcomestorectilinearmotion,itisfullydeterminedbythefirsttwolawsandGod’sconservationofthingsthewaytheyare,inthecaseofcircularmotion,anextraexplanatoryprincipleisrequired,viz.,thedispositionsofmatter.Thisexplainswhythoughthepartsofabodytendtomoveinstraightline,thebodyasawholemovesinacircle.Hereishowheputit(1998,30):“Accordingtothisrule[thethirdlawofmotion],then,wemustsaythatGodaloneistheauthorofallthemotionsintheworldinsofarastheyexistandinsofarastheyarestraight,butthatitisthevariousdispositionsofmatterthatrenderthemotionsirregularandcurved.Likewise,thetheologiansteachusthatGodisalsotheauthorofallouractions,insofarastheyexistandinsofarastheyhavesomegoodness,butthatitisthevariousdispositionsofourwillsthatcanrenderthemevil”.9HereIaminagreementwithGarber(1992,298)whotakesthelinethatCartesianforcesarenothingbutwaysoftalkingabouthowGodactsonbodiesinalawfulway.But,asitwillbecomeclearlateron,IaddtoGarber’saccountthat,strictlyspeaking,Descartesreplacesforceswithlawsinthesensethatthereisnothingmoretothecontentofforce-talkthanwhateverisinvolvedinthelaw-governedmotionofbodies.FormoreonthevariousaccountsofforceinDescartesseeGarber(1992,chapter9),Ayers(1996)andOtt(2009,chapter8).
9
period(1982,63).Descartessaysthatthe“forceofeachbodytoactagainstanotherortoresisttheactionofthatotherconsists”(…)“inthesinglefactthateachthingstrives,asfarasisinitspower,toremaininthesamestate,inaccordancewiththefirstlawstatedabove”(op.cit.).Forcesofactionorresistancearereplacedbylaw-likebehaviour.HereisasummaryofthemainfeaturesofCartesianlaws.
Lawsaredifference-makers:allphenomenainnaturearecounterfactuallydependentonlaws.Ifthelawshadbeendifferent(perimpossibile),theworldwouldhavebeendifferent.Lawsarecounterfactuallyrobust:Nomatterwhattheinitialarrangementofparticlesinmotion,thelawsaresuchthattheeffectwouldbethesame.Whicheffect?Theworldasweknowit.Lawsaremetaphysicallynecessary:Godagitatedthedifferentpartsofmatterindiverseways,butthenHe“didnomorethansustainnatureinHisusualmannerleavingittoactaccordingtothelawsHehasestablished”.Theselawsaresuchthat“evenifGodhadcreatedmanyworlds,therecouldbenotbeanyinwhichtheycouldhavefailedtobeobserved”(1998,31).Lawsareimmanent:theydirectlyfollowfromGod’simmutability.Lawsarecausalprinciples:themotionofthevariousbodiesintheworldhappenbecauseofthemandnotsimplyaccordingtothem.Thepassivityofmatter,however,createdapotentialtensionintheCartesian
system:Howarelawsexecutedbymatter?Ifmatterisinertandlacksanymotorforce,howisitthatpiecesofmatteraresubjectedtothecausalactionoflaws?Descartesisclearthatbodieshave“noinnatetendencytomotion”(PartIII,26;1982,94).Nordotheyhaveany“tendencytowardsrest”(PartII,37;1982,59).Allactionisbycontactandrequiresamover.Hethereforeputsforwardsevenrulesbyvirtueofwhichthecollisionofbodiesisregulated.Thoughtheseruleswerehavebenfoundwanting,therelevantpointhereis
thatDescartesintroducesthemasruleswhich“determinetowhatextentthemovementofeachbodyischangedbycomingincontactwithotherbodies”(partII,45;1982,64).Thiswaytoformulatethetaskisfullyconsistentwiththeclaimthatmatterispassiveandhencethatrules(laws)determinehow(thequantityof)motionisredistributedamongthecollidingbodies.ButinshowinghowtheserulesapplytocontactsamongmovingbodiesDescartesstatedthat“itisonlynecessarytocalculatehowmuchforcetomoveortoresistmovementthereisineachbody;andtoacceptasacertaintythattheonewhichisthestrongerwillalwaysproduceitseffect”(PartII,45;1982,64).Hence,itisnotclear,tosaytheleast,thatDescarteshasacoherentviewabouthowmatteriscapabletoactonmatterandbeacteduponbymatter.InalattertoMore(August1649),Descartesnotedthatacreatedsubstancecanhavethepowertomoveabody;butthisisamodeofthecreatedsubstanceconferredonitbyGod(cf.1991,381).Stillcanmotionbetransferredfromonebodytoanother?Ifmotionisamodeofthethingmoved(asitcertainlyis),thenitcannotsincenomodecanbetransferredfromonebodytoanother.Butaswehavealreadyseen,Descartesrepeatedlytalksasifmotionisbeingtransferredfromonebodytoanotherbecauseofthelawsofmotion.InPrincipia(II,25;1982,51)Descartesdefinedmotionas
thetranslationofonepartofmatterorofonebody,fromthevicinityofthosebodies
10
immediatelycontiguoustoitandconsideredasatrest,intothevicinityof[some]others.(…)Ialsosaythatitisatranslation,nottheforceoractionwhichtransfers[nonvimvelactionemquaetransfert],inordertoshowthatthismotionisalwaysinthemovingbodyandnotinthethingwhichmovesit(becauseitisnotusualtodistinguishbetweenthesetwowithsufficientcare);andinordertoshowthatitisonlyamode[ofthemovingbody],andnotasubstance,justasshapeisamodeofthethingshaped,andrest,ofthethingwhichisatrest.
Inthiscriticalpassage,hedistinguishedclearlybetweenmotionastranslation
(i.e.,changeofrelativeplace]andmotionasforceoractionwhichistransferredfromonebodytoanother.ButinmanyotherplacesinthePrincipiaDescartestalksfreelyofthe‘transference’onmotion(seee.g.,II,40&42).AcharitablereadingofDescarteswouldbethis.Strictlyspeaking,thereisnotransferofmotionbetweenbodies(though,looselyspeakingtheircollisionscanbedescribedasifthereweretransfer).Still,whenbodiescollidewitheachother,thequantitiesofmotiontheyalreadypossessarere-distributedamongthemaccordingtotherelevantlaws(andalwaysinlinewiththeoverarchingprinciplePCQM).Thelawsthenarethe(particularandsecondary)causes(difference-makers)ofthere-distributionofparticularquantitiesofmotion,sincewithoutthemtherewouldbenofactofthematterastowhatwouldhappenedinthecollision.4.OccasionalistLawsTheoccasionalistreactiontoDescarteswasbasedonthethoughtthatifmatteristrulyinertandlackingofanymotivepower,thentheonlyreal(anddirect)causeshouldbeGodhimself.ForMalebranche,wehavenoconceptionofpowerofsecondarythings.Iftheonlymotivepoweris(in)God,howdoesGodactonmatter?Theanswerisclear:vialaws.Godactsvialawsbecausehisactionisuniformandsimple;it“link(s)togetherthepartswhichcomposetheworld”andmakestheworldknowable(1923,190).Hence,lawsarewilledbyGod.LawsareprinciplesbymeansofwhichGodactsinnatureandestablishesitsuniformity—whichisafacetofitsperfection.ForMalebranche,Godsubmitstolawsnotbyabsolutenecessitybutbydesire
(TreatiseonNatureandGrace(TNG),XXI;1992,119).Beingomnipotent,Godcouldhavecreatedaninfinityofpossibleworlds.Hence,therecouldhavebeenalaw-less(disorderly)world.ButGoddidnotdesiretocreatesuchaworld;hence,hedidnotwillit.Godcreatedanorderlyworld,governedbythesimplestlawssinceHeacts“alwaysbythesimplestways”(TNG,XVII;1992,118).Infact,ofallthepossible(law-governed)worlds,hewilledtocreate“thatworldwhichcouldhavebeenproducedandpreservedbythesimplestlaws,andwhichoughttobethemostperfectwithrespecttothesimplicityofthewaysnecessarytoitsproductionortoitsconservation”.(TNG,XIII;1992,116)Soperfectionisafunctionofthesimplicityofthewaystheworldcouldhavebeencreatedandconserved.Ashesayslateron:“ifhehadbeenable(byequallysimpleways)tomakeandtopreserveamoreperfectworld,hewouldneverhaveestablishedthoselaws”(TNG,XXII;1992,120).UnlikeCartesianlaws,Malebrancheanlawsarenotgroundedinthe
immutabilityofGodbutinhisWilland,inparticular,inhiswaysofacting.HealwaysactsinthesimplestwaysandHealwaysacts(inthenaturalorder)withgenerallaws(volitions).Godwillscertainlaws“becauseoftheirfruitfulness”.
11
(TNG,XIX;1992,119)Whatthenarethelawsofnature?TheyareGod’sgeneralvolitions.Theyare
hisdecrees.Assuch,thelawsofnaturearenotmetaphysicallynecessary.Thedecrees(laws)ofGodareonlyexhypothesisnecessary.Hence,thequestion‘CanGodchangethelaws?’admitsofapositiveanswer.LikeDescartes,MalebranchethoughtthatGodcouldhavenotsetmatterinmotion(ifhehadwishednottoproduceanythingnewintheworld).Butinaddition,Godmightwillthattheactuallawsofmotionchange(if,forinstance,hewillstocreateincorruptiblebodies). Thoughlawscouldbedifferent(orcouldchange,ifGodwilledit),theyareconstantandimmutableandtheyholdeverywhereandeverywhen.Hecouldn’tbemoreexplicit:“Thelawsofnatureareconstantandimmutable;theyaregeneralforalltimesandforallplaces”(TNGXVIII;1992,118).Infact,itistheveryconstancyandimmutabilityoflawsthatexplainswhyinnaturethereareunwanted(orundesirable)effects—e.g.haildestroysaharvestoramalformedbabyisborn.ForMalebranche,itisnotthatGodwilled,withaparticularvolitiontheseparticulareffectstohappen.Rather,theseeffectsarethe“necessaryconsequences”ofthelawsofcommunicationofmotionhehadinitiallyestablished(TNG,XVIII;1992,118).Goddesiresthat“allofhiscreaturesshouldbeperfect”(op.cit.);Butheactsbygenerallawswhichheforeseestobethemostfecund(cf.TNG,XXII;1992,119).Thesearealsothesimplestlaws.PreciselybecauseGodactsinthesimplestways,itwouldbe“unworthyofhiswisdomtomultiplyhiswillsinordertostopcertainparticulardisorders”.Hence,simpleandgenerallaws‘cover’everythingthathappensinnature,withinthenatural(i.e.,notmiraculous)order. Thetwofundamentallawsofnaturearelawsofmotion:TheFirstLaw:“thatmovedbodiestendtocontinuetheirmotioninastraight
line”;(TNG,XV;1992,117) TheSecondLaw:“thatwhentwobodiescollide,theirmotionisdistributedbothinproportiontotheirsize,suchthattheymustafterwardsmoveatanequalspeed”(TNG,XV;1992,117).Accordingtothesecondlaw,whathappensincollisionsisthere-distribution
ofmotion“inproportiontotheirsize”.AsMalebranchenotedthislawisnotobservedinexperience;buthenotedthatitisatruelawholdinginthe“invisible”bodies”(TNG,XVI;1992,117). InDialoguesonMetaphysics(Dialogue7,XI),thefirstlawofmotionwasjustifiedonthegroundsthatthestraightlineisthesimplestandshortestline.Whenitcomestothesecondlaw,henotedthatthoughthereischangeofdirection,thereisconservationofthe“quantityofthemovingforce”(1923,191).Thesetwoprinciplesconstitute“thegenerallawsofthecommunicationofmovementsinaccordancewithwhichGodactsincessantly”(op.cit)(cf.alsoResearche,ElucidationXV;1997,664). Malebrancheanlawsofnatureare“efficacious”;10inparticular,itisbecauseoftheefficacyofthesecondlaw(governingimpact)thatdiversityinmatterisproduced:thediversitythereisinmatteriscounterfactuallydependentonthesecondlawofmotion.Butmorethanthis,bothlawsarethecauseofallmotion:“Thesetwolawsarethecauseofallthemotionswhichcausethatvarietyof
10AsRobertMerrihewAdams(2013,75)aptlyputit,Malebrancheanlaws“have‘oomph’”.
12
formswhichweadmireinnature”(TNG,XV;1992,115).Theyare“necessarytotheproductionandthepreservationoftheearth,andofallthestarsthatareintheheavens”(op.cit.).Whateverhappensinnature(barringGod’smiraculousintervention)isthenecessaryconsequenceofthelawsofmotion.Buthowarelawsexecutedbymatter?ForMalebranche,theyarenot!God
himselfexecutesthelaws.Thelawsarethedivinedecreesthemselves,whichgroundtheregularity.Thelawsareprinciplesofconnection(“indissolublebondsofunion”)betweennaturalthings(distinctexistences).AsheputitinDialogue7,XIII(1923,195):“thedivinedecreesaretheindissolublebondsofunionbetweenthevariouspartsoftheuniverseandofthemarvelousnetworkofallthesubordinatecauses”.AsMalebranchestressed,thetwobasicprinciplesofwhatcametobeknown
asoccasionalismarethese:1. Bodieslackmotorforce.2. Godactsonnatureviagenerallaws.Hereishowheputit:
thesetwoprinciples,ofwhichIamconvinced,thatnonebuttheCreatorofbodiescanbetheirmover,andthatGodcommunicatesHispowertousonlythroughtheestablishmentofcertaingenerallaws,therealisationofwhichwedeterminethroughourvariousmodifications(Dialogues,7,XIV;1923,196).
Sincematterisimpotenttoexecutethelaws,theymustbe‘executed’byGod;yet,asisexplicitlystatedintheforegoingpassage,thelawsare‘realised’invariousnatural(i.e.,occasional)causes(viatheirmodifications).Inthisscheme,thereisnoroomforconnectingentitieslikepowers/activequalities.ThelinkbetweenGod(astheonlypower)andtheregularitythereisinnatureislaws—thatisGod’sdecreeswhicharedirectlyrealisedinnaturalbodiesandtheirmotions(cf.Dialogues7,XIII;1923,195).Hence,lawsbeingthe“indissolublebondsofunionbetweenthevariouspartsoftheuniverse”areexecutedbyGodandarerealisedinnaturalbodiesandtheirregularbehaviour. HowarelawsexecutedbyGod?WhenHere-createsabodyinmotion,Hemakesitmovealwaysinastraightlineaccordingtothefirstlaw,i.e.,thesubsequentre-creationsshouldbeinaccordancetothefirstlaw.ThisisGod’sgeneralvolition.Buttherearecollisions.Again,thelawofcollisionsdeterminesthatthere-createdbodieswillbesuchthatthereisacertainre-distributionofmotionamongthem.InacollisionbetweenbodyXandbodyY,XisnotthecauseofthemotionofY.Xcommunicates“nothingofitsown”toY.Yet,thereisalaw-governedre-distributionofmotionbetweenXandY.Godactsaccordingtoalawwhichcausesthere-distributionofmotion.HencethoughallcommunicationsofmotionareexecutedbyGod,theyareexecutedbyagenerallaw.Theactionofnaturalcausesconsists“onlyinthemotorforceactivatingthem”,i.e.,God(Researche,ElucidationXV;1997,662).DoesthatmeanthatGodcommunicateshispowertobodies?Notquite!Godhasmadethemodificationsofbodiestheoccasionalcausesofhisaction—whichislaw-governed(cf.1997,225).ThereisanongoingdebateamongMalebranche’sscholarsaboutthecontent
oflawsofnature—aretheygeneralvolitionsor(sumsof)particularvolitions?11
11SeePessin2001;Ott2009,chapter11;Nadler2011;RobertMerrihewAdams2013forarepresentativesample.
13
AsMalebrancheexplains,whenGodactswithaparticularvolition,heactswithouttheoccasionalcause,e.g.,whenIfeelpainwithoutbeingprickedbyapin.Orwhenabody“beginstomoveitselfwithoutbeingstruckbyanother,orwithoutanychangeinthewillofminds,orinanyothercreaturethatdeterminestheefficacyofsomegenerallaws,IsaythenthatGodmovesthisbodybyaparticularwill”(TNG,IllustrationII;1992,195).Butwhathappenswhenaballstrikesanother?HowdoesGodact?Malebranche’sansweristhatGodmovesthesecondballbyageneralvolition(agenerallaw).Theballismoved“inconsequenceofthegeneralandefficaciouslawsofthecommunication”(cf.alsoTNG,IllustrationI;1992,195).SoitseemscorrecttosaythatMalebrancheanlawsaregeneralvolitions.Malebrancheanlawsofnaturearenotmetaphysicallynecessary.Butarethey
contingent?Theyarenot.Aswehaveseen,Godsubmitshimselftolawsnotoutofabsolutenecessitybutoutofhiswillforthegood.Malebranchealsostressesthat,toputitinmodernjargon,regularitydoesnotimplycausation;necessityisalsoneeded.Hence,“OnlyinthewisdomofGoddoweseeeternal,immutable,andnecessarytruths.NowhereelsebutinthiswisdomdoweseetheorderthatGodHimselfisconstrainedtofollow(Recherche;Elucidation10;1997,615-6).InafamouspassageinhisLarecherchédelaverite,Malebranchemakesclearthatwecanconceiveofabsolute(metaphysical)necessityonlybetweenthewillofGodandsomethinghappeningbecauseofthis:
AtruecauseasIunderstanditisonesuchthatthemindperceivesanecessaryconnectionbetweenitanditseffect.Nowthemindperceivesanecessaryconnectionbetweenthewillofaninfinitebeinganditseffect.Therefore,itisonlyGodwhoisthetruecauseandwhotrulyhasthepowertomovebodies(1997,450).
Sincethereisnoperceptionbythemindofnecessaryconnectionsbetweennatural(oroccasional)causesandnatural(oroccasional)effects,thesearenotrealcauses.Foranynaturalcause,itisconceivablewithoutcontradictionthatitcanoccurwithoutitseffect.Andofcourse,Godcanmakeithappenthatthatitdoesoccurwithoutits(natural)effect.OnlyinthecaseofGod’swillisitimpossibleforustoconceiveofitwithoutatthesametimeconceivingwhateveritwillstohappen.But,barringmiraculousinterventions,naturalcausesinvariablyprecedetheirnaturaleffectsinvirtueofGod’sgeneralvolitions,akalawsofnature.Hence,theregularitythereisinnature(invirtueofwhichitispredictableandknowable)isgroundedin(inthesenseofbeingtheeffectof)thelawsofnature.Thelawisnottheregularityitself,butitistheprinciple(God’sgeneralvolition)whichgroundstheregularity. Theoccasionalcausedoesnotact—thoughitmightseemtousthatitdoes.Itisthelawthatiscausallyefficacious:“Abodymovesimmediatelyafterhavingbeenstruck:thecollisionofthebodiesistheactionoftheoccasionalcause;thusthisbodymovesbyageneralwill”(op.cit.).Occasionalcausesandtheconcomitantregularityisasignthattheeffectdoesnothave“somethingsingularaboutit”.Hence,thepresenceofanoccasionalcauseissign(“mark”)thatthereisactionbythegeneralvolitionofGod(IllustrationVIII).Hence,regularity(occasional‘causation’)isa‘mark’forthepresenceofalawbymeansofwhichGodacts.BeingthedecreesofGod,lawsholdwithsomekindofnecessity.Recallthe
verytitleofMalebranche’sTreatise:OntheNecessityofGeneralLawsofNature.
14
Whatkindofnecessityisthis?Itisnaturalorhypotheticalnecessity.Eventhoughthenaturalnecessityofthelawscannotpossiblyberationallyinferredfromtheobservationoftheinvariableconjunctionofnaturalcausesandnaturaleffects,itcanbeconceivedifwereflectonthewayGodacts.Thelawsofnaturearecertainlypartofthefabricofnature;hence,thereisnecessityinnature;thoughthisnecessityisnotlocatedorgroundedinbodies“bythemselves”;norcanitinferredbyexperienceandfromtheregularitythereisinnature.12 5.BerkeleyonLawsThatlawsarenaturallynecessaryisaviewthat,perhapssurprisingly,canbeattributedtoBerkeleytoo.ForBerkeley,allcausationisanactionofthewillofaspirit.Hence,onlyGodandminds(spirits)canbe(efficient)causes.Ideasarepassiveandinert(Principles§25;2008,92).Thoughitisfalsetoclaimthatideasarethe“effectsofpowersresultingfromtheconfiguration,number,motion,andsizeofcorpuscles”,ideasmustnonethelesshaveacause“whereontheydepend,andwhichproducesandchangesthem”(Principles§26;2008,92).Thesecanonlybeincorporealsubstances(i.e.,mindsquaactivesubstances).Godexcites(andcauses)ideasinusbymeansoflawsofnature.Thisclaimis
groundedinthefactthatideashave“admirableconnexions”andregularity;theycome“inaregulartrainorseries”(Principles§30).Sotheorderandregularityintheco-occurrenceandsuccessionofideassuggestthattheyarecausedinusbyaWillwhichactsinanorderlyandregularway.AsBerkeleyputit:“Thesetofrulesorestablishedmethods,whereinthemindwedependonexcitesinustheideasofsense,arecalledthe‘lawsofnature’;andthesewelearnbyexperience,whichteachesusthatsuchandsuchideasareattendedwithsuchandsuchotherideasintheordinarycourseofthings”(Principles§30;2008,94).LawsofnaturestemfromGod’sWill.TheyareexpressionsofGod’sWilltoact
inaregularway:“(T)hisconsistentuniformworking,whichsoevidentlydisplaysthegoodnessandwisdomofthatgoverningspiritwhosewillconstitutesthelawsofnature”(§32;2008,94).Butunlikeallofhispredecessors,Berkeleytookitthatlawsofnatureareknownbyobservationandempiricalstudy.Theyarenotknownapriori.TheyarenotinferredbyreferencetothesimplicityofGod’sactionsorhisimmutability.Theydoreflecthisgoodnessandwisdomincreatingtheworld,buttheycanonlybeknownaposteriori.Inparticular,lawsarenotdiscoveredaprioribylookingfor“necessaryconnectionsamongideas”.Thereisnothingintheideaoffirethatnecessarilyimpliesthatitwarmsus.Theregularitythereisintheworldisdiscoveredempirically“onlybytheobservationofthesettledlawsofnature”(§31;2008,94).Thankstothelawsofnature,ideasareconnectedtoeachother(e.g.,theideaoffireandtheideathatitwarmsus)eventhoughonemaybeconceivedwithouttheotherwithoutfallingintocontradiction. Inacertainsense,Berkeleypushedthecaseforoccasionalismtoitsextremes.Malebrancheanoccasionalismkeptmatterbutdivesteditfromanycausalpowerorefficacy.Hence,therearenocorporealcauses.Withoutnamingit,Berkeley(Principles§53)notedthatoccasionalismgotitrightinclaimingthat“amongst
12HereIaminessentialagreementwithRobertAdamswhostressesthatforMalebranchethereisnecessitationincausationinthefollowingsense:occasionalcausesare“partofhowGod’sgeneralvolitions,asefficaciouslawsofnature,necessitateparticulareffects”(2013,77).
15
alltheobjectsofsense,therewasnonewhichhadanypoweroractivityincludedinit,andthatbyconsequencethiswaslikewisetrueofwhateverbodiestheysupposedtoexistwithoutthemind”(2008,103).Buthethoughtthatthefurthersupposition,viz.,thatthereis“aninnumerablemultitudeofcreatedbeings,which(…)arenotcapableofproducinganyoneeffectinnature”is“unaccountableandextravagant”,thoughpossible. IfBerkeleyfoundinoccasionalismnoargumentforthephilosophicalcategoryofmater,hefoundinitanunderstandingofhowGodactsintheworld:vialawsofnature.Inthissense,lawsofnaturearekeytoBerkeley’snaturalphilosophy.Asheputit(Principles§62;2008,107):
Therearecertaingenerallawsthatrunthroughthewholechainofnaturaleffects.Thesearelearnedbytheobservationandstudyofnature,andarebymenappliedaswelltotheframingartificialthingsfortheuseandornamentoflifeastotheexplainingthevariousphenomena:whichexplicationconsistsonlyinshowingtheconformityanyparticularphenomenonhastothegenerallawsofnatureor,whichisthesamething,indiscoveringtheuniformitythereisintheproductionofnaturaleffects,aswillbeevidenttowhoevershallattendtotheseveralinstances,whereinphilosopherspretendtoaccountforappearances.
Thisrichpassagesuggeststhefollowingaboutlaws:
a) Laws“runthrough”thewholechainofnaturaleffects.Hence,lawscoverallnaturaleffects(thewholechainofeventsinnature).Thiscoveringshouldnotbeseenas‘governing’butas‘runningthrough’—laws‘permeate’naturalphenomena;theimbuenaturalphenomena.
b) Theselaws,asnotedalready,arediscoveredaposteriori;theyarelearnedbyobservationandempiricalstudyofnature.
c) Explanationinnaturalphilosophyisshowingthatparticularphenomenaconformtoagenerallaw;thatis,thattheyare‘permeated’byalaw.Hence,explanationcanbeseenasnomologicalsubsumption.
d) The‘production’ofnaturaleffectsisnothingmorethantheirlaw-basedexplanation—thatis,theirpermeationbylaws.
Godactsvialawsatalllevels.Andbecauseofthis,heproduces(literallythis
time,sinceHe’sanefficientcause)anyeffect“accordingtothestandingmechanicallawsofnature”(op.cit.).AsBerkeleyrepeatedlystresses,thisisnotanecessarytruth—itisnot“absolutelynecessary”forGodtoproduceanyeffectbymechanicalprinciples.Yet,themetaphysicalcontingencyofthe‘clockworkofnature’doesnotdetractfromthefactthatGodwillstoact“agreeablytotherulesofmechanism”.Infact,giventhatBerkeleydoeswanttoaccommodatemechanism(theclockworkofnature)withinhisphilosophy,hefurtherarguesthatalthoughGodcouldproduceanythinghewantedwithoutanymechanism,the‘clockworkofnature’isthewayGodhaschosentoproduceeffectsinnatureinaregularandorderlyway.Hence,themechanicallawsofnatureareconditionallyornaturallynecessary,viz.necessary“totheproducing[ofaneffect]accordingtothestandingmechanicallawsofnature”. InDeMotu,inwhichBerkeleymakesanattempttoexplainhisnaturalphilosophywithoutexplicitlydenyingthatthereismatter,heexpresseshisfirmviewthat“(R)egardingbodywemayboldlydeclareasestablishedfactthatitisnottheprincipleofmotion”(2008,250).Headdsthatwhatweknowaboutthe
16
body(whatiscontainedintheideaofbody—“extension,solidity,andfigure”)isnotaprincipleofmotion.Andin§24hedismissesthattheremightbesomethingunknowninbodywhichisthisprincipleofmotion,becausewehavenoideaofit.Lawsofnature,then,‘replace’internalprinciplesofmotionofbodies.In
scienceitisenoughtostatetruetheoremsaboutthemotionofthebodies,irrespectiveofwhatmightormightnotcausethesemotions.Thesetruetheoremsare“therulesandlawsofmotion”andthe“theoremsdeducedfromthem”,(regulis&legibusmotuum,simulactheoremataindededucta).Andtheselaws“remainunshaken,solongassensibleeffectsandreasoningbasedonthemaregranted”(2008,252).Thereislittledoubt,however,thateventhoughlawsarediscoverableaposteriori,theyholdwithnaturalnecessityandpermeatetheactualbehaviourofthings.6.LeibnizonLawsandPowersMalebranchedidadopttheprincipleoftheconservationoftotalquantityofmotion.InDialogueX,(1923,267),henoted:“Inaword,Godhaschosenthesimplestlawonthebasisoftheuniqueprinciplethatthestrongershallconquertheweaker;and,subjecttothiscondition,thatthereshallalwaysbeintheworldthesamequantityofmotion”.ButheneverfollowedtheCartesiancourseoftryingtogroundthelawsofmotiononthisprincipleandtheimmutabilityofGod.Hedidattribute“movingforce”toGodandclaimedthatGodacts“alwayswiththesameefficacyorthesamequantityofmovingforce”(Dialogue7;1923,191).Thetotalquantityofmovingforceisconserved,sinceasMalebrancheputit,God“neverchangesthequantityofthemovingforcewhichanimatesmatter”(op.cit). Asiswellknown,aprincipleddisagreementbetweentheCartesiansandLeibnizconcernedwhatexactlyisconservedduringimpact.Alreadyin1686,LeibniznotedthatthereisagreatdifferencebetweentheconceptofthequantityofmotionandtheconceptofquantityofmotiveforceandthatDescarteswasmistakeninholdingthemtobeequivalent.ThismistakeledDescartes,Leibnizargued,to“toassertthatGodconservesthesamequantityofmotionintheworld”(1989,296).ButthisbasicCartesianprinciplePCQMwasnotcorrect,asLeibnizconclusivelydemonstrated.Whatisconservedisthetotalquantityofvisviva,whichistheproductofmasstimesthesquareofthevelocityofabody.AsLeibnizputit,whatisconservedisthe“totalforceandthetotaldirection”.Wewillnotgointothedetailsofthispresently.WhatisimportantforourpurposesisthatLeibnizpresentsthisprinciple—theconservationofthequantityofforce—asasubordinatelawofnature(DiscourseonMetaphysics,§17). Thefundamentallawofnatureisalawoforder.TheworldisorderlyandregularandforLeibniz“nomatterhowGodmighthavecreatedtheworld,itwouldalwayshavebeenregularandinacertaingeneralOrder”(Discourse§6;1989,306).Hence,thisfundamentallawismetaphysicallynecessary.Butthemostorderlyworldcouldhavebeenthemostcomplexone.LeibniznotesthatGodchosetocreatethemostperfectworld,whereperfectionisafunctionoftwofactors—simplicityandstrength.Asheputit:“ButGodhaschosenthatworldwhichisthemostperfect,thatistosay,whichisatthesametimethesimplestinitshypothesesandtherichestinphenomena”(op.cit.).Sothesimplestworldisatthesametimethemostcomprehensiveworld. Thisworldisstructuredbysubordinatelaws.TheseareGod’sgeneral
17
volitions.Theygoverneverythingwithoutexceptions:“ForthemostgeneralofGod’slaws,whichrulesthewholesequenceoftheuniverse,iswithoutexception”(Discourse§7;1989,307).Thelawoftheconservationofthequantityofforceisthechiefsubordinatelawofnature.ItisgroundeddirectlyinGodinthatitisGodwho“alwaysconservesbyrulethesameforce”(Discourse§17;1989,314).Elsewhere(1989,499),hecallstheLawofconservationofquantityofforce“thefoundationofthelawsofnature”implyingthatamongthesubordinatelawsthereisahierarchyoflaws,withPCQFbeingatthebottom. Butwhatisforceoractivepower?Leibniztakesittobeanon-mechanicalquality,whichisnecessaryforexplainingthebehaviourofthings.Itisnon-mechanicalinthesensethatitisnotoneofthebasicmechanicalcategoriesofCartesianism,viz.,extension,figureandmotion.It’snotgeometricalanditisattributedtonaturalbodiesoverandabovetheirmechanicalaffections.Infact,giventhatthebasiclawofnatureistheconservationofthequantityofforce,Leibnizarguesthatinfindingthe“truelawsofnatureandtherulesofmotion”,wehavetogobeyondmechanicsandphysicstometaphysics(Discourse§18;1989,315).Wehavetoascertaintheforces(thatisthe“immediatecauses”ofmotionsandchangesinnature).Forcesare“morereal”thantheireffects(changesinmotion)andbecauseforcesare“differentfromsize,figure,andmotion”,wecanconcludethat“noteverythingwhichisconceivedinabodyconsistssolelyinextensionanditsmodifications”(op.cit.).Leibniztooktheneedtoappealtoforcestovindicatethemedieval-Aristotelianviewthatbodieshaveactiveandpassivepowers,whicharenotmechanicallyexplicableandgrounded.Rather,they“pertaintocertainformsorindivisiblenatures”ofcorporealsubstances(op.cit.).Thekeycharacteristicofforces,whicharedirectly“implanted”tocorporealbodies“bytheCreator”,isthatbybeingsubjectedtoforces,bodiesareendowed“withconatus,attaining[their]fulleffectunless[theyare]impededbyacontraryconatus”(1989,440).Thisforceisinthe“bodiesthemselves”and“itconstitute(s)theinmostnatureofthebody,sinceitisthecharacterofsubstancetoact”(1989,435).Restoringforcesorpowersasbeinginherentinbodieswasanimportant
breakwithCartesianism.Matterisnotpassivebutactive.ButLeibnizadoptedtheideathatthemotionsofpiecesofmatterissubjecttonaturallaws,whichareestablishedbyGod.Thoughnotmetaphysicallynecessary,thelawsarefarfrom“arbitrary”.GodhaschosenthembutasLeibnizputit,“Godhasbeenledtosetinmotionthelawswhichareobservedinnaturethroughdeterminedprinciplesofwisdomandbyreasonsoforder”(1989,500).Inthissense,wecansaythatlawsofnatureareconditionallyornaturallynecessaryinthatgivenGod’sdemandforsimplicityandstrength(i.e.,perfection)inanorderlyworld,theseparticularlawshadtobechosen.InalettertoMalebranche(June22/July21679),heputthispointthus:“WemustalsosaythatGodmakesthemaximumofthingshecan,andwhatobligeshimtoseeksimplelawsispreciselythenecessitytofindplaceforasmanythingsascanbeputtogether;ifhemadeuseofotherlaws,itwouldbeliketryingtomakeabuildingwithroundstones,whichmakeuslosemorespacethantheyoccupy”(1989,211).Hisgeneralreactiontooccasionalismrevealshisviewsabouttherelation
betweenlawandpower.Hischiefpointisthatthoughoccasionalistsarerightindenyingthatthereisinteractionamongbodies,andinparticular,indenyingthedirectinfluxtheoryaccordingtowhichacauseiswhatflowsintotheeffect
18
(hencethatsomethingflowsbetweentwodistinctsubstances),theyarewronginplacingallactioninGod,therebyturninghimintoaDeusexMachina.Occasionalism,forLeibniz,introduces“akindofcontinuousmiracle”(1989,338).Itis“asifGodasaruleinterferedinsomeotherwaythanbypreservingeachsubstanceinitscourseandinthelawsestablishedforit”(op.cit.).ThoughhisdiagnosisofhowGodactsaccordingtooccasionalismmightwellbewrong,sinceforMalebrancheatleastGodneednotactbyanythingotherthanhisgeneralvolition,Leibnizpointstoagenuineproblemwithoccasionalism,viz.,thatlawsareexecuteddirectlybyGodhimselfandnotbynaturalbodies.SoLeibniztookitthatacompleteunderstandingoftheworkingsofnaturerequiresbothlawsofnatureandpowerfulsubstances.HeidentifiedakeyproblemforbothCartesianismandoccasionalism.IcallitLeibniz’sproblem:Howcanpassivematter‘obey’laws?Howarelawsexecutedifmatterdoesnothavewhatittakestheexecutethem?InhisreplytoBayle’scriticismin1698,Leibnizstressedthateventhough
generallawsaredecreesofGod,theyareinneed“ofanaturalmeansofcarrying[them]out”;hence,“allthathappensmustalsobeexplainedthroughthenaturewhichGodgivestothings”(1989,494).Inhis‘OntheNatureitself,orontheInherentForceandActionsofCreatedThings”,(1698),Leibnizgavethefollowingargumentfortheneedtomakebodiespowerfulandcausallyefficacious.LawsarecertainlyGod’sdecrees;butforbodiestobeabletoexecutethelawsinthefuture,somethingmusthavebeen“impresseduponcreatures”byGodwhichmakesthemcapabletoactaccordingtothelaw.Forotherwisetherearenonecessaryconnectionsbetweencausesandeffects;thecommand(God’slaw)iseithernotbindingatfuturemomentsor“itmustalwaysberenewedinthefuture”.Thecommand(thelaw),whichwassetinthebeginningoftime,isbindingnowandinthefutureonlyif“thelawsetupbyGoddoesinfactleavesomevestigeofhimexpressedinThings”.Andthisimpliesthat“thereisacertainefficacyresidinginthings”;(andcreaturesingeneral).Itisthisefficacywhichmakesthem“capableoffulfillingthewillofhimwhocommandedthem”.Thisefficacyispartoftheirnatureandit’saforce“fromwhichtheseriesofphenomenafollowsaccordingtotheprescriptionofthefirstcommand”(cf.1989,501).Leibniz’sargumentimpliesthatbothlawsandinherentpowersarerequired
fortheexplanationofnaturalphenomena.Butpowersareindividuatedindependentlyoflaws;theyarepresupposedfortheexistenceofnecessaryconnectionsinnatureinthesensethatpowersarerequiredforthingstoobeylawsandforthelawstobebinding.InhislettertoHartsoeker(Hanover,10February1711),Leibnizmakesclearthatitisnotenoughfortheidentificationofapowertostatealawthatitobeys(orsimplythatthereislaw);whatisalsorequiredisthespecificationofthemechanismbymeansofwhichthispoweracts.Themechanismis,clearly,ontopofthelawandgivenindependentlyofit.Withoutthemechanismthepoweris“anunreasonableoccultquality”.Hesays:
Thustheancientsandthemoderns,whoownthatgravityisanoccultquality,areintheright,iftheymeanbyitthatthereisacertainmechanismunknowntothem,wherebyallbodiestendtowardsthecenteroftheearth.Butiftheymeanthatthethingisperformedwithoutanymechanismbyasimpleprimitivequality,orbyalawofGod,whoproducesthateffectwithoutusinganyintelligiblemeans,itisanunreasonableoccultquality,andso
19
veryoccult,thatitisimpossibleitshouldeverbeclear,thoughanangel,orGodhimself,shouldundertaketoexplainit(inNewton2004,112).
Thebottomlineisthatquadivinecommands,lawsarebindingonlyifbodies
arecapableoffollowingthemnecessarily—andthisisgroundedintheir“impressednature”.Fundamentally,theirimpressednature(“thesubstanceofthingsitself”,asLeibnizputit),“consistsintheforceofactingandbeingactedupon”(1989,502).Thisis“aprimitivemotiveforce”,whichis“superadded”toextensionandmassandgroundsmotionandaction.Forreasonwhichwecannotgointohere,Leibnizidentifiesthisprimitiveforcewithasoulorsubstantialform.7.HumeandNewtononLawsandNecessityRecently,therehasbeenconsiderablecontroversyaboutwhatHumethoughtaboutnecessity.Thetrendistointerprethisascepticalrealist,whilethetraditionalviewwasthathewasadenialist.ForreasonsthatIcannotgointonow,Ithinkthatthetraditionalviewisessentiallycorrect:Humedeniedthatthereisanypowerinnature;hencehedeniedthatthereisanynecessityinnature(seemy2003,chapter1foradiscussion).Humedidnotdenythattherearelawsofnature.However,theselawsdonotgovern;norisitthecasethatworldlythingsobeythem,inanyinterestingsense.Lawsarejusttheregularitiesthemselvesandnothingmore.Reflectingonthequestionofnecessitythatthelawsofmotionallegedlyhave,Humesaid:
Thedegreeanddirectionofeverymotionis,bythelawsofnature,prescribedwithsuchexactness,thatalivingcreaturemayassoonarisefromtheshockoftwobodies,asmotion,inanyotherdegreeordirectionthanwhatisactuallyproducedbyit.Wouldwe,therefore,formajustandpreciseideaofnecessity,wemustconsiderwhencethatideaarises,whenweapplyittotheoperationofbodies(Enquiry,SectionVIII,PartI,82).
Theideaofnecessity,whichofcourseHumeneverdoubtedthatwepossessandthatitispartofthecommonunderstandingofcausation,isaprojectionofthehumanmindonnature,whichisconditionedbytheexistenceofuniformityandregularityonnature:
Ouridea,therefore,ofnecessityandcausationarisesentirelyfromtheuniformity,observableintheoperationsofnature;wheresimilarobjectsareconstantlyconjoinedtogether,andthemindisdeterminedbycustomtoinfertheonefromtheappearanceoftheother.Thesetwocircumstancesformthewholeofthatnecessity,whichweascribetomatter.Beyondtheconstantconjunctionofsimilarobjects,andtheconsequentinferencefromonetotheother,wehavenonotionofanynecessity,orconnexion(Enquiry,SectionVIII,PartI,82).
Newton’sattitude,whichofcourseprecededHume’s,wasquitedifferent.13OnmyreadingofNewton,thereispowerinnaturebutpowersandlawsaremutuallydetermined—tointroduceapoweristointroducealaw.Interestingly,Newtondidallowthatthereisnecessityinnature;butthisnecessityis,fromanempirical-scientificpointofview,ineffable. TosubstantiatethepointthatforNewtonpowersandlawsaremutuallydetermined,weshouldbrieflycomparehimwithDescartes.InDefinitionIIIof
13MyunderstandingonNewtonhasbeeninfluencedbylongdiscussionswithRobertDiSalle.
20
thePrincipia,Newtonintroducesthepower(vis)ofmatterofresistingacceleration(changeofstateofmotion)bymeansofalaw.Hesays:“Inherentforceofmatter(visinsita)isthepowerofresistingbywhicheverybody,sofarasitisable(quantuminseest),perseveresinitsstateeitherofrestingorofmovinguniformlystraightforward”(2004,60).Let’scomparethiswithNewton’sfirstlawofmotion:“Everybodyperseveresinitsstateofbeingatrestorofmovinguniformlystraightforward,exceptinsofarasitiscompelledtochangeitsstatebyforcesimpressed”(2004,45).TheDefinitiondefinesapowerabodyhasintrinsically,viz.,thepowertopersevereinitsstateofmotion(i.e.,thepowertoresistchangesinitsstateofmotion),bystatingthelawitobeysquantuminseest.14Inthestatementofthefirstlaw,ontheotherhand,Newtondescribesthelawabodyobeysbystatingwhathappenstoabodyiftheintrinsicpowertopersevereinitsstateofmotionistheonlyonethatispresentandacting.i.e.,ifthebodyisquantuminseest.Thedefinitionhasthedirectionfromthepowertothelaw;thelawhasthedirectionfromthelawtothepower.Awaytocombinethetwowouldbethefollowing:Everybodyobeysthefirstlawofmotion(itperseveresinitsstateofbeingatrestorofmovinguniformlystraightforward)ifandonlyitsvisinsitaistheonlypoweractingonthebody.Inthissense,apowerisdefinedbythelawthebodythathasitobeys;andconversely,alawstateswhatabodydoesinvirtueofapoweritpossesses.15 Descartes,bycontrast,simplystatedthelaw:“thateachthing,asfarasisinitspower(quantuminseest),alwaysremainsinthesamestate;andthatconsequently,whenitisoncemoved,italwayscontinuestomove”(II,37;1982,59).Inhiscase,aswehavealreadynoted,thereisnopowertobedefined;thelawsimplyreplacesthepower.Intrinsically.i.e.,quantuminseest,thebodyobeysthelaw(italwaysremainsinthesamestateofmotion). InthePrefacetothesecondeditionofthePrincipiain1713,whichwaswrittenbyRogerCotesundertheclosesupervisionofNewton,CotescarefullydistinguishedNewton’sviewsfromthoseoftheAristoteliansaswellasfromthoseoftheCartesians.ThechiefpointmadeagainsttheAristotelianswasthattheypositedsuigenerispowersandthiswasredundantandnon-explanatory.Coteswrote:
Therehavebeenthosewhohaveendowedtheindividualspeciesofthingswithspecificoccultqualities,onwhich–theyhavethenalleged–theoperationsofindividualbodiesdependinsomeunknownway.ThewholeofScholasticdoctrinederivedfromAristotleandthePeripateticsisbasedonthis.Althoughtheyaffirmthatindividualeffectsarisefromthespecificnaturesofbodies,theydonottellusthecausesofthosenatures,andthereforetheytellusnothing(2004,43).
Notethecomplaintaboutthe“unknownway”onwhichtheoperationsofbodiespossessingacertainpowerdepend.Newton’semphasisonlawsindefiningpowerswasmeant,amongotherthings,tocapture,andhencetoexplain,howpowersact:theyactvialaws;better:tointroduceapoweristointroducethelawthatthingsthatpossessitobey.Thereisnoexplanatorygaphere.Nounknown14FormoreontheimportanceofQuantuminSeEstseeI.BernardCohen(1964).15AsGeorgeSmith(2002,151)nicelyputit:“Thelawcharacterizingaforcefromaphysicalpointofviewgivesits“physicalproportions”andassignsittoa“physicalspecies.”Twoforcesareofthesamephysicalspeciesonlyiftheyarecharacterisedbythesamelaw”.
21
modusoperandi. ButCotesgoesontocriticisetheCartesianwaytoo.Asiswell-known,hischiefpointagainsttheCartesiansintheprefacewasthattheyrecoursetounfoundedhypothesesandspeculationsaboutthemechanicalcausesofthephenomena.IttranspireshoweverthatCotes’srealcomplaintwasthattheydoallthisinordertoavoidtheAristotelianpitfallofpowers.Theytrytorectifythesuigenerisandnon-explanatorynatureofAristotelianpowersbyavoidingpowersaltogetherandbyappealing,instead,tomechanicalhypothesesaboutmatterinmotion.HereishowCotesputsthepointwhenitcomestowhatCartesianssayaboutgravity:
Foreithertheywillsaythatgravityisnotapropertyofallbodies–whichcannotbemaintained–ortheywillassertthatgravityispreternaturalonthegroundsthatitdoesnotarisefromotheraffectionsofbodiesandthusnotfrommechanicalcauses.Certainlythereareprimaryaffectionsofbodies,andsincetheyareprimary,theydonotdependonothers(2004,51).
Hence,thepricethattheCartesianwayoutcomeswithiseitheradenialthatgravityisauniversalpropertyofbodiesorthatgravityisamysteriousproperty(power)ofthingssinceitisnotexplainedandgroundedmechanically(i.e.,bymeansofalaw-obeyingconfigurationofmatterinmotion).WhenthenCotesstatesthatthereare“primaryaffectionsofbodies”,andthatbeingprimary,theseaffections(gravitybeingoneofthem)“donotdependonothers”,hecarvesoutpreciselythemiddleroadthatNewtonsuggested,viz.,tointroduceaprimaryaffectionofmatterwhichisneitheroccult(astheAristotelianswouldhaveit)normysterious(astheCartesianswouldhaveit)onewouldhavetointroduceitbymeansofthelawitobeys,evenifthislawwasnotmechanical.ItakeitthenthatCotes’sandNewton’sviamediawastokeepbothpowers(againsttheCartesians)andlaws(againsttheAristotelians)buttoclaimthattheyareintroducedhand-in-hand—especiallywhenitcomestotheprimary(andhencenot-further-reducible)powersofmatter. Cotesmakesthispoint(fairly)clearlywhenhetalksaboutgravitybeingsuchaprimaryaffection:“Amongtheprimaryqualitiesofallbodiesuniversally,eithergravitywillhaveaplace,orextension,mobility,andimpenetrabilitywillnot.Andthenatureofthingseitherwillbecorrectlyexplainedbythegravityofbodiesorwillnotbecorrectlyexplainedbytheextension,mobility,andimpenetrabilityofbodies”(2004,50).Gravityisnotanoccultpower(eventhoughwemaynotknowitscause)because,asNewtonputitintheGeneralScholium,“itisenoughthatgravityreallyexistsandactsaccordingtothelawsthatwehavesetforthandissufficienttoexplainallthemotionsoftheheavenlybodiesandofoursea”(2004,92). Hence,theNewtonianmethod,asexplainedbyCotesisaviamedia:“Fromcertainselectedphenomenatheydeducebyanalysistheforcesofnatureandthesimplerlawsofthoseforces,fromwhichtheythengivetheconstitutionoftherestofthephenomenabysynthesis”(emphasisadded)(2004,44). Newton,asiswellknown,didallowthattheremightbeanunknowncauseofgravity.Sohemightbetakentohaveallowedthattheremightbewaystoidentifypowersindependentlyofthelawstheyobey.Buthewasadamantthatthiskindofindependentidentification,ifpossibleatall,shouldnotbetakenasarequirementforalegitimateappealpowers;specifyingthelawthattheyobeyis
22
enoughforscientificpurposes.InanunsentletterwrittencircaMay1712totheeditoroftheMemoirsofLiterature,NewtonreferredexplicitlytoLeibniz’slettertoHartsoeker,andstressedthatitisnotnecessaryfortheintroductionofapower—suchasgravity—tospecifyanythingotherthanthelawitobeys;noextrarequirementsshouldbeimposed,andinparticularnorequirementforamechanicalgrounding.Hesaid:
Andthereforeifanymanshouldsaythatbodiesattractoneanotherbyapowerwhosecauseisunknowntous,orbyapowerseatedintheframeofnaturebythewillofGod,orbyapowerseatedinasubstanceinwhichbodiesmoveandfloatwithoutresistanceandwhichhasthereforenovisinertiaebutactsbyotherlawsthanthosethataremechanical:Iknownotwhyheshouldbesaidtointroducemiraclesandoccultqualitiesandfictionsintotheworld(2004,116).
ThereishardlyanyneedtorelatehereNewton’sthreelawsofmotion.16What’simportanttonoteisthatforNewtontheselawswerenotmetaphysicallynecessary.AsCotesputit:
Itistheprovinceoftruephilosophytoderivethenaturesofthingsfromcausesthattrulyexist,andtoseekthoselawsbywhichthesupremeartificerwilledtoestablishthismostbeautifulorderoftheworld,notthoselawsbywhichhecouldhave,haditsopleasedhim(2004,52).
Thereislittledoubtthatlawsrequiredalaw-makerandthiswasGod.But,forNewton,significantlyandunlikeDescartes,Godcouldhaveestablisheddifferentlaws.Hence,thelawsaremetaphysicallycontingent;theycouldbedifferentfromwhattheyare.Thetaskthenofnaturalphilosophyistodiscovertheactuallawsofnature—theonesGoddidestablish.ThekeypointhereisthatsinceGodcouldhaveestablishedotherlaws,findingtheactuallawscannotamatterofaprioritheorising(asDescartessuggested)butofabroadlyempiricalinvestigation.Indeed,Cotessays:
Fromthissource[God’sperfectlyfreewill],then,haveallthelawsthatarecalledlawsofnaturecome,inwhichmanytracesofthehighestwisdomandcounselcertainlyappear,butnotracesofnecessity.Accordinglyweshouldnotseektheselawsbyusinguntrustworthyconjectures,butlearnthembyobservingandexperimenting(2004,57).
Howcanitbethattherearenotracesofnecessityinthelawsofnature?Iflawsweremetaphysicallynecessarytherewouldbeknownapriori;henceindependentlyofexperience.ButforNewtonandCotestherecannotbeaprioriknowledgeoflawsofnature,sincethelawsarefreechoicesofGod.AndiflawswheremetaphysicallynecessarytheywouldnotthefreechoiceofGod.Hencethereisadilemma:eithertheclaimisthatlawsholdwithmetaphysicalnecessity,butthenthiswouldnotmakethelawsthefreechoiceoftheauthoroftheuniverse;ortheclaimisthatGodwasfreeinthechoiceoflaws,butthentheycannotbeknownapriori.ThefirsthornistakenbyDescartes;thesecondbyNewton.Cotesputsthepointthus:
Hewhoisconfidentthathecantrulyfindtheprinciplesofphysics,andthelawsofthings,
16ForsomeinsightfulpointsconcerningmathematicalandphysicalcharacterisationsofforcesbyNewton,seeJaniak(2007).Therelevantliteratureis,ofcourse,vast.
23
byrelyingonlyontheforceofhismindandtheinternallightofhisreasonshouldmaintaineitherthattheworldhasexistedfromnecessityandfollowsthesaidlawsfromthesamenecessity,orthatalthoughtheorderofnaturewasconstitutedbythewillofGod,neverthelessacreatureassmallandinsignificantasheishasaclearunderstandingofthewaythingsshouldbe(2004,57).
Partofthepointisthatknowingthelawsofnatureaprioriwouldbepossibleonlyontwoconditions:eitheriftherecouldbeonlyonewaythelawscouldbe;andhencethelawsweremetaphysicallynecessary;or,shouldthelawsbemetaphysicallycontingent,ifthehumanmindhadthecapacitytolatchontothemindependentlyofexperience.BothconditionsaredeniedbyNewton.Sotothequestion:‘Whatmakesthelawslaws,ultimately?’Newton’sansweris:thewillofGod.GiventhatthelawsaregroundeddirectlyinthewillofGod,theycannotbutbeinsomesensenecessary:onceGodwillsthem,theycannotbutholdandgovernthebehaviourofthings.Buythisisnotmetaphysicalnecessitybutconditionalornaturalnecessity.Inthissense,forNewtontherearenaturallynecessaryconnectionsinnature,expressedbythefundamentallawsofnature,buttheonlywaytofindthemoutisempirically(andhencefallibly).Newtonthen,unlikeHume,takesittobethecasethatlawsarenotmere
regularities;however,hetakesitthattheycanbeknownonlyas(mathematicallycharacterised)regularities.Thisleadstoadrasticreconceptualisationoflawsofnatureasprimarilymathematicalprincipleswhichcharacterisethebasicstructureoftheworldandplaceconstraintsontheexplanationanddescriptionofnaturalprocesses,butareknownempiricallyandnotapriori.InhisunsentlettertoCotes,inMarch1713,Newtonnoted:
IlikeyourdesignofaddingsomethingmoreparticularlyconcerningthemannerofphilosophizingmadeuseofinthePrincipiaandwhereinitdiffersfromthemethodofothers,viz.bydeducingthingsmathematicallyfromprinciplesderivedfromphenomenabyinduction.Theseprinciplesarethethreelawsofmotion.Andtheselawsinbeingdeducedfromphenomenabyinductionandbackedwithreasonandthethreegeneralrulesofphilosophizingaredistinguishedfromhypothesesandconsideredasaxioms.Uponthesearefoundedallthepropositionsinthefirstandsecondbook.Andthesepropositionsareinthethirdbookappliedtothemotionsoftheheavenlybodies(2004,109-110).
8.ConcludingthoughtsDuringtheseventeenthcentury,thereisaclearshiftfrompowersasregularityenforcerstolawsasregularity-enforcers.Medievalpowersyieldedabottom-upnecessity:lawsweremetaphorsfornaturallynecessaryconnectionsamongpowerfulsubstances.Butduringtheseventeenthcentury,lawsreplacednaturalpowersasprinciplesofconnection.Lawsyieldatop-downnecessity.Theyderivetheirnecessityfromalaw-giverandtheydeterminehowthingsmustbehaveintheworld;thatis,theygroundandexplaintheregularpatternsthereareintheworld.Laws,inthissense,are‘behind’theregularitythereisintheworldandgroundit. Aswehaveseen,however,lawskeptakeyfeatureofpowers:theyimposednecessaryconnectionsinnature,thoughtherewasashiftinhowexactlynecessitywasconceived.Cartesianlawsholdwithmetaphysicalnecessity;notsofortherestofthethinkersweexamined:lawsholdwithnaturalnecessityandimposepatternsofnaturallynecessaryconnectionsinnature.
24
Theshiftfrompowerstolawscamewithatension,whichwasaccentuatedbythefactthatmatterwastakentobeinertandcausallyinactive.Thistensioniscapturedbythefollowingtwoquestions:Howcanthingsobeylawsiftheydonothavethepowertodoso?Howcanapowerlessmatterexecutethelaws?Lawsaresupposedtogovernthebehaviourofthings;thingsinsomesense
obeythemandhenceexecutethem.ButasLeibnizforcefullyargued,formattertobecapableofexecutingalaw,mattermusthavesuitablepowers.WithLeibnizpowersre-enterthestageasthatinvirtueofwhichbodiesaresubjecttolawsandabletoexecute/obeythelaws.Lawsthenseemtorequirepowerstoenforcenecessaryconnectionsintheworld.Buthowdoobjectsacquiretheirpowers?ForLeibniz,aswehaveseen,powersareidentifiedindependentlyoflaws.Buttwootheranswerstothisquestionbecameavailable.OnewasHume’s,
andtheotherwasNewton’s.ForHume,therearenopowers.Thelawsofnatureareregularities.ForNewton,powersandlawsentertheworldhand-in-hand,asitwere.UnlikeHume,Newtonwasfarfromacceptingthatthereisnonaturalnecessity.Still,ofthisnecessitynothingcanbeknownexceptwhateverisgiventousas(mathematicallycharacterised)regularities.Ifthereisnaturalnecessityinnature,(Newtonthinksthereis),itcanneverbefoundout.Butlet’scompareNewtonwithHumeoncemore:IfGodisleftoutofthe
picture,andifnaturalnecessitycannotbeotherwisegroundedin(theindependentlyposited)naturesorpowersallweareleftwithareregularitieswhichcanbeknownonlyas(mathematicallycharacterised)regularities(andneverquanaturalnecessities).These,plausibly,arethelawsofnatureforbothHumeandNewton.AcknowledgementIwouldliketothankLydiaPattonandWalterOttfortheirimmensepatienceandencouragement.Walter’sworkhasbeenagreatsourceofinspirationandideas.ManyoftheideasexpressedinthispaperwereextensivelydiscussedwithRobertDiSalleandStavrosIoannidis,whomIthankwholeheartedly.EarlierversionsofthispaperwerepresentedinaninvitedtalkattheRotmanInstituteofPhilosophy-EngagingScienceinJune1016;aspartofasymposium(inabsentia)intheHoPoSConferenceinMinneapolisinJune2016;andintheinauguralConferenceofthePOND-PhilosophyofSciencearoundtheMediterraneaninJerusaleminSeptember2016.Mythanksgotoseveralmembersoftheaudiencesforcommentsandquestions.ReferencesAdams,RobertMerrihew.2013.‘Malebranche’sCausalConcepts’.InEricWatkins
(ed.)TheDivineOrder,theHumanOrder,andtheOrderofNature,Oxford:OxfordUniversityPress.
Ayers,Michael.1996.‘NaturesandLawsfromDescartestoHume’.InG.A.J.RogersandSylvanaTomaselli(eds)ThePhilosophicalCanonintheSeventeenthandEighteenthCenturies:EssaysinHonourofJohnW.Yolton.UniversityofRochesterPress.
Berkeley,George.2008.PhilosophicalWritings.CambridgeTextsintheHistoryofPhilosophy.DesmondClarke(ed.).Cambridge:CambridgeUniversityPress.
Cohen,I.Bernard.1964.‘’QuantuminSeEst’:Newton’sConceptofInertiainRelationtoDescartesandLucretius’.NotesandRecordsoftheRoyalSociety
25
ofLondon19:131-155.Descartes,R.1982.PrinciplesofPhilosophy.Miller,V.R.andMiller,R.P.(trans)
Dordrecht:D.ReidelPublishingCompany.DescartesRene.1984.ThePhilosophicalWritingsofDescartes.J.Cottingham,R.
Stoothoff,andD.Murdoch(edsandtrans).2vols.Cambridge:CambridgeUniversityPress.
DescartesRene.1991.ThePhilosophicalWritingsofDescartes.Volume3:TheCorrespondencebyReneDescartes;JohnCottingham;RobertSoothoff;DugaldMurdoch;AnthonyKenny(edsandtrans).Cambridge:CambridgeUniversityPress.
Descartes,Rene.1998.TheWorldandOtherWritings.CambridgeTextsintheHistoryofPhilosophy.StephenGaukroger(ed.).Cambridge:CambridgeUniversityPress.
Garber,Daniel.1992.Descartes’MetaphysicalPhysics.Chicago:UniversityofChicagoPress.
Garber,Daniel.2013.‘God,Laws,andtheOrderofNature:DescartesandLeibniz,Hobbes and Spinoza’. In EricWatkins (ed.),TheDivineOrder, theHumanOrder,andtheOrderofNature.Oxford:OxfordUniversityPress.
Garber,Daniel.2016.‘NaturalPhilosophyinSeventeenth-CenturyContext’,inAl.P.Martinich&K.Hoekstra(eds),TheOxfordHandbookofHobbes,Oxford:OxfordUniversityPress.
Goudarouli,Irene&Psillos,Stathis.Forthcoming.‘HobbesonLawsofNature:FromDeCorporetoLeviathanandBackAgain’
Henry,J.2004.‘MetaphysicsandtheOriginsofModernScience:DescartesandtheImportanceofLawsofNature’.EarlyScienceandMedicine9:73-114.
Hume, David. 2007. AnEnquiryconcerning HumanUnderstanding.PeterMillican(ed.).Oxford:OxfordUniversityPress.
Janiak,Andrew.2007.‘NewtonandtheRealityofForce’.JournaloftheHistoryofPhilosophy45:127-147
Leibniz,G.W.1989.PhilosophicalPapersandLetters.ASelectionTranslatedandEdited, with an Introduction by Loemker. 2nd edition. Dordrecht: KluwerAcademicPublishers.
Malebranche,Nicolas.1923.DialoguesonMetaphysicsandonReligion.MorrisGinsberg(trans).London:GeorgeAllen&UnwinLtd.
Malebranche,Nicolas.1992.TreatiseonNatureandGrace.PatrickRiley(trans).Oxford:ClarendonPress.
Malebranche,Nicolas.1997.TheSearchafterTruth.CambridgeTextsintheHistoryofPhilosophy. T.M. LennonandP. J.Olscamp,Trans. Cambridge:CambridgeUniversityPress.
McCordAdams,Marilyn.2013.‘PowersversusLaws:GodandtheOrderoftheWorldAccordingtoSomeLateMedievalAristotelians’.InEricWatkins(ed.),TheDivineOrder,theHumanOrder,andtheOrderofNature,Oxford:OxfordUniversityPress.
Nadler,Steven.2011.Occasionalism:CausationamongtheCartesians.Oxford:OxfordUniversityPress.
Newton,Isaac.2004.PhilosophicalWritings.CambridgeTextsintheHistoryofPhilosophy.AndrewJaniak(ed.),Cambridge:CambridgeUniversityPress.
Ott,Walter.2009.CausationandLawsofNatureinEarlyModernPhilosophy.Oxford:ClarendonPress.
26
Pessin,Andrew.2001.‘Malebranche’sDistinctionbetweenGeneralandParticularVolitions’.JournaloftheHistoryofPhilosophy39:77-99
Psillos,Stathis,2002.CausationandExplanation.Acumen.Smith,George.2002.‘TheMethodologyofthePrincipia’.InI.BernardCohen
andGeorgeSmith(eds)TheCambridgeCompaniontoNewton.Cambridge:CambridgeUniversityPress.
Suárez,Francisco.1944.SelectionsfromThreeWorksofFranciscoSuárez,2volumes,translatedbyG.L.Williams,A.Brown&J.Waldron,withrevisionsbyH.Davis,Oxford:ClarendonPress;London:H.Milford.
Watkins,Ericed.2013.TheDivineOrder,theHumanOrder,andtheOrderofNature,Oxford:OxfordUniversityPress.
Related Documents
