第2章
加入书架 A- A+
点击下载App,搜索"A Defence of Free—Thinking in Mathematics",免费读到尾

  andconsideredinthe`Analyst。’Andherethequestionbetweenusis,whetherIhaverightlyrepresentedthesenseofthosewordsevanescantjamaugmentailla,inrenderingthem,``lettheincrementsvanish,’’i。e。lettheincrementsbenothing,orlettherebenoincrements?Thisyoudeny;but,asyourmanneris,insteadofgivingareasonyoudeclaim。I,onthecontrary,affirm,theincrementsmustbeunderstoodtobequitegone,andabsolutelynothingatall。Myreasonis,becausewithoutthatsuppositionyoucanneverbringthequantityorexpressiondownto,theverythingaimedatbysupposingtheevanescence。Saywhetherthisbenotthetruthofthecase?Whethertheformerexpressionisnottobereducedtothelatter?

  Andwhetherthiscanpossiblybedonesolongasoisarealquantity?

  Icannotindeedsayyouarescrupulousaboutyouraffirmations,andyetIbelievethatevenyouwillnotaffirmthis;itbeingmostevident,thattheproductoftworealquantitiesissomethingreal;andthatnothingrealcanberejectedeitheraccordingtotheofgeometry,oraccordingtoSirIsaac’sownPrinciples;forthetruthofwhichIappealtoallwhoknowanythingofthesematters。Further,byevanescentmusteitherbemeant,letthem(theincrements)vanishandbecomenothing,intheobvioussense,orletthembecomeinfinitelysmall。ButthatthislatterisnotSirIsaac’ssenseisevidentfromhisownwordsintheverysamepage,thatis,inthelastofhis`IntroductiontotheQuadratures,’whereheexpresslysaith,voluiostenderequodinmethodofluxionumnonopussitfigurasinfiniteparvasingeometriamintroducere。Uponthewhole,youseemtohaveconsideredthisaffairsoverysuperficiallyasgreatlytoconfirmmeintheopinionyouaresoangrywith,towit,thatSirIsaac’sfollowersaremuchmoreeagerinapplyinghismethodthanaccurateinexamininghisprinciples。Youraiseadustaboutevanescentaugments,whichmayperhapsamuseandamazeyourreader,butIammuchmistakenifiteverinstructsorenlightenshim。For,tocometothepoint,thoseevanescentaugmentseitherarerealquantities,ortheyarenot。Ifyousaytheyare;Idesiretoknowhowyougetridoftherejectaneousquantity?Ifyousaytheyarenot;youindeedgetridofthosequantitiesinthecompositionwhereoftheyarecoefficients;butthenyouareofthesameopinionwithme,whichopinionyouarepleasedtocall(p。58)``amostpalpable,inexcusable,andunpardonableblunder,’’

  althoughitbeatruthmostpalpablyevident。

  34。Nothing,Isay,canbeplainertoanyimpartialreaderthanthat,bytheevanescenceofaugmentsintheabove—citedpassage,SirIsaacmeanstheirbeingactuallyreducedtonothing。But,toputitoutofalldoubtthatthisisthetruth,andtoconvinceevenyou,whoshewsolittledispositiontobeconvinced,Idesireyoutolookintohis``AnalysisperAequationesInfinitas’’(p。20),where,inhispreparationfordemonstratingthefirstruleforthesquaringofsimplecurves,youwillfindthat,onaparalleloccasion,speakingofanaugmentwhichissupposedtovanish,heinterpretsthewordevanescerebyessenihil。Nothingcanbeplainerthanthis,whichatoncedestroysyourdefence。Andyet,plainasitis,Idespairofmakingyouacknowledgeit;

  thoughIamsureyoufeelit,andthereaderifheusethhiseyesmustseeit。Thewordsevanesceresiveessenihildo(touseyourownexpression)stareusintheface。Lo!Thisiswhatyoucall(p。56)``sogreat,sounaccountable,sohorrid,sotrulyBoeotianablunder,’’thataccordingtoyou,itwasnotpossibleSirIsaacNewtoncouldbeguiltyofit。Forthefuture,Iadviseyoutobemoresparingofhardwords;since,asyouincautiouslydealthemabout,theymaychancetolightonyourfriendsaswellasyouradversaries。Asformypart,Ishallnotretaliate。Itissufficienttosayyouaremistaken。ButIcaneasilypardonyourmistakes。

  Though,indeed,youtellme,onthisveryoccasion,thatImustexpectnoquarterfromSirIsaac’sfollowers。AndItellyouthatIneitherexpectnordesireany。Myaimistruth。MyreasonsIhavegiven。Confutethem,ifyoucan。Butthinknottooverbearmeeitherwithauthoritiesorharshwords。Thelatterwillrecoiluponyourselves。Theformer,inamatterofscience,areofnoweightwithindifferentreaders;and,asforbigots,Iamnotconcernedaboutwhattheysayorthink。

  35。Inthenextplaceyouproceedtodeclaimuponthefollowingpassage,takenfromtheseventeenthsectionofthe`Analyst。’

  ``Consideringthevariousartsanddevicesusedbythegreatauthorofthefluxionarymethod;inhowmanylightsheplacethhisfluxions;andinwhatdifferentwayheattemptstodemonstratethesamepoint:onewouldbeinclinedtothinkhewashimselfsuspiciousofthejustnessofhisowndemonstrations。’’ThispassageyoucomplainofasveryhardusageofSirIsaacNewton。Youdeclaimcopiously,andendeavourtoshowthatplacingthesamepointinvariouslightsisofgreatusetoexplainit;whichyouillustratewithmuchrhetoric。Butthefaultofthatpassageisnotthehardusageitcontains:but,onthecontrary,thatitistoomodest,andnotsofullandexpressiveofmysenseasperhapsitshouldhavebeen。

  WouldyoulikeitbetterifIshouldsay—``Thevariousinconsistentaccountswhichthisgreatauthorgivesofhismomentumsandhisfluxionsmayconvinceeveryintelligentreaderthathehadnoclearandsteadynotionsofthem,withoutwhichtherecanbenodemonstration?’’IownfranklythatIseenoclearnessorconsistenceinthem。Youtellme,indeed,inMiltonicverse,thatthefaultisinmyowneyes,``Sothickadropserenehasquench’dtheirorbs,Ordimsuffusionveil’d。’’Atthesametimeyouacknowledgeyourselfobligedforthosevariouslightswhichhaveenabledyoutounderstandhisdoctrine。Butasforme,whodonotunderstandit,youinsultme,saying:``ForGod’ssake,whatisityouareoffendedat,whodonotstillunderstandhim?’’MaynotIanswer,thatIamoffendedforthisveryreason—becauseIcannotunderstandhimormakesenseofwhathesays?YousaytomethatIamallinthedark。

  Iacknowledgeit,andentreatyouwhoseesoclearlytohelpmeout。

  36。YouSir,withthebrighteyes,bepleasedtotellme,whetherSirIsaac’smomentumbeafinitequantity,oraninfinitesimal,oramerelimit?Ifyousayafinitequantity:bepleasedtoreconcilethiswithwhathesaithinthescholiumofthesecondlemmaofthefirstsectionofthefirstbookofhisPrinciples:Caveintelligasquantitatesmagnitudinedeterminatas,sedcogitasemperdiminuendassinelimite。

  Ifyousay,aninfinitesimal:reconcilethiswithwhatissaidinhis`IntroductiontotheQuadratures’:Voluiostenderequodinmethodofluxionumnonopussitfigurasinfiniteparvasingeometriamintroducere。Ifyoushouldsay,itisamerelimit;bepleasedtoreconcilethiswithwhatwefindinthefirstcaseofthesecondlemmainthesecondbookofhisPrinciples:UbidelateribusAetBdeerantmomentorumdimidia,&c。,wherethemomentsaresupposedtobedivided。Ishouldbeverygladapersonofsuchaluminousintellectwouldbesogoodastoexplainwhetherbyfluxionswearetounderstandthenascentorevanescentquantitiesthemselves,ortheirmotions,ortheirvelocities,orsimplytheirproportions:and,havinginterpretedtheminwhatsenseyouwill,thatyouwouldthencondescendtoexplainthedoctrineofsecond,third,andfourthfluxions,andshewittobeconsistentwithcommonsenseifyoucan。Youseemtobeverysanguinewhenyouexpressyourselfinthefollowingterms:``Idoassureyou,Sir,frommyownexperience,andthatofmanyotherswhomIcouldname,thatthedoctrinemaybeclearlyconceivedanddistinctlycomprehended’’(p。

  31)。Anditmaybeuncivilnottobelievewhatyousosolemnlyaffirm,fromyourownexperience。ButImustneedsownIshouldbebettersatisfiedofthis,if,insteadofentertaininguswithyourrhetoric,youwouldvouchsafetoreconcilethosedifficulties,andexplainthoseobscurepointsabovementioned。ifeitheryou,oranyoneofthosemanywhomyoucouldnamewillbutexplaintootherswhatyousoclearlyconceiveyourselves,Igiveyoumywordthatseveralwillbeobligedtoyouwho,Imayventuretosay,understandthosemattersnomorethanmyself。But,ifIamnotmistaken,youandyourfriendswillmodestlydeclinethistask。

  37。Ihavelongagodonewhatyousooftenexhortmetodo—diligentlyreadandconsideredtheseveralaccountsofthisdoctrinegivenbythegreatauthorindifferentpartsofhiswritings;

  anyuponthewholeIcouldnevermakeitouttobeconsistentandintelligible。

  Iwasevenleadtosaythat``onewouldbeinclinedtothinkhewashimselfsuspiciousofthejustnessofhisowndemonstrations;andthathewasnotenoughpleasedwithanyonenotionsteadilytoadheretoit。’’AfterwhichIadded,``Thismuchisplain,thatheownedhimselfsatisfiedconcerningcertainpoints,whichneverthelesshecouldnotundertaketodemonstratetoothers。’’(Seetheseventeenthsectionofthe`Analyst。’)Itisonethingwhenadoctrineisplacedinvariouslights;andanotherwhentheprinciplesandnotionsareshifted。Whennewdevicesareintroducedandsubstitutedforothers,adoctrineinsteadofbeingillustratedmaybeexplainedaway。Whethertherebenotsomethingofthisinthepresentcase,Iappealtothewritingsofthegreatauthor—his`MethodusRationumPrimarumetUltimarum,’hissecondlemmainthesecondbookofhis`Principles,’

  his`IntroductionandTreatiseoftheQuadratureofCurves。’Inallwhich,itappearstome,thereisnotoneuniformdoctrineexplainedandcarriedthroughoutthewhole,butrathersundryinconsistentaccountsofthisnewMethod,whichstillgrowsmoredarkandconfusedthemoreitishandled:

  Icouldnothelpthinking,thegreatestgeniusmightlieundertheinfluenceoffalseprinciples;andwheretheobjectandnotionswereexceedinglyobscure,hemightpossiblydistrustevenhisowndemonstrations。``Atleastthusmuchseemedplain,thatSirIsaachadsometimesownedhimselfsatisfied,wherehecouldnotdemonstratetoothers。InproofwhereofImentionedhislettertoMr。Collins;hereuponyoutellme:thereisagreatdealofdifferencebetweensaying,Icannotundertaketoproveathing,andIwillnotundertakeit。’’But,inanswertothis,IdesireyouwillbepleasedtoconsiderthatIwasnotmakingapreciseextractoutofthatletter,inwhichtheverywordsofSirIsaacshouldalonebeinserted。

  ButImademyownremarkandinferencefromwhatIrememberedtohavereadinthatletter;where,speakingofacertainmathematicalmatter,SirIsaacexpressethhimselfinthefollowingterms:``IsisplaintomebythefountainIdrawitfrom,thoughIwillnotundertaketoproveittoothers。’’Now,whethermyinferencemaynotbefairlydrawnfromthosewordsofSirIsaacNewton,andwhetherthedifferenceastothesensebesogreatbetweenwillandcaninthatparticularcase,Ileavetobedeterminedbythereader。

  38。Inthenextparagraphyoutalkbigbutprovenothing。Youspeakofdrivingoutofintrenchments,ofsallying,andattacking,andcarryingbyassault;ofslightanduntenableworks,ofanew—raisedandundisciplinedmilitia,andofveteranregulartroops。Needthereaderbeamathematiciantoseethevanityofthisparagraph?Afterthisyouemploy(p。65)yourusualcolouring,andrepresentthegreatauthoroftheMethodofFluxions``asagoodoldgentlemanfastasleepandsnoringinhiseasychair;whileDameFortuneisbringinghimherapronfullofbeautifultheoremsandproblems,whichheneverknowsorthinksof。’’Thisyouwouldhavepassforaconsequenceofmynotions。ButIappealtoallthosewhoareeversolittleknowinginsuchmatters,whethertherearenotdiversfountainsofexperiment,induction,andanalogy,whenceamanmayderiveandsatisfyhimselfconcerningthetruthofmanypointsinmathematicsandmechanicalphilosophy,althoughtheproofsthereofaffordedbythemodernanalysisshouldnotamounttodemonstration?Ifurtherappealtotheconscienceofallthemostprofoundmathematicians,whethertheycan,withperfectacquiescenceofmind,freefromallscruple,applyanypropositionmerelyuponthestrengthofademonstrationinvolvingsecondorthirdfluxions,withouttheaidofanysuchexperiment,oranalogy,orcollateralproofwhatsoever?Lastly,Iappealtothereader’sownheart,whetherhecannotclearlyconceiveamediumbetweenbeingfastasleepanddemonstrating?

  But,youwillhaveitthatIrepresentSirIsaac’sconclusionsascomingoutright,becauseoneerroriscompensatedbyanothercontraryandequalerror,whichperhapsheneverknewhimselfnorthoughtof:thatbyatwofoldmistakehearrivesthroughnotatscienceyetattruth:thatheproceedsblindfold,&c。Allwhichisuntrulysaidbyyou,whohavemisappliedtoSirIsaacwhatwasintendedfortheMarquisdel’Hospitalandhisfollowers;

  fornootherend(asIcansee)butthatyoumayhaveanopportunitytodrawthatingeniousportraitureofSirIsaacNewtonandDameFortune,aswillbemanifesttowhoeverreadsthe`Analyst。’

  39。Youtellme(p。70)ifIthinkfittopersistinasserting``thatthisaffairofadoubleerrorisentirelyanewdiscoveryofmyown,whichSirIsaacandhisfollowersneverkneworthoughtof,thatyouhaveunquestionableevidencetoconvincemeofthecontrary,andthatallhisfollowersareclearlyapprisedthatthisveryobjectionofminewaslongsinceforeseen,andclearlyandfullyremovedbySirIsaacNewton,inthefirstsectionofthefirstbookofhis`Principia。’’’AllwhichIdoasstronglydenyasyouaffirm。AndIdoaverthatthisisanunquestionableproofofthematchlesscontemptwhichyou,Philalethes,havefortruth。AndIdoherepubliclycalluponyoutoproducethatevidencewhichyoupretendtohave,andtomakegoodthatfactwhichyousoconfidentlyaffirm。And,atthesametime,Idoassurethereaderthatyouneverwill,norcan。

  40。IfyoudefendSirIsaac’snotions,asdeliveredinhis`Principia,’itmustbeontherigorousfootofrejectingnothing,neitheradmittingnorcastingawayinfinitelysmallquantities。IfyoudefendtheMarquis,whomyoualsostyleyourMaster,itmustbeonthefootofadmittingthatthereareinfinitesimals,thattheymayberejected,thattheyareneverthelessrealquantities,andthemselvesinfinitelysubdivisible。

  Butyouseemtohavegrowngiddywithpassion,andintheheatofcontroversytohavemistakenandforgotyourpart。Ibeseechyou,Sir,toconsiderthattheMarquis(whomalone,andnotSirIsaac,thisdoubleerrorinfindingthesubtangentdothconcern)rejectsindeedinfinitesimals,butnotonthefootthatyoudo,towit,theirbeinginconsiderableinpracticalgeometryormixedmathematics。Butherejectsthemintheaccuracyofspeculativeknowledge:inwhichrespecttheremaybegreatlogicalerrors,althoughthereshouldbenosensiblemistakeinpractice;which,itseems,iswhatyoucannotcomprehend。Herejectsthemlikewiseinvirtueofapostulatum,whichIventuretocallrejectingthemwithoutceremony。And,thoughheinferrethaconclusionaccuratelytrue,yethedothit,contrarytotherulesoflogic,frominaccurateandfalsepremises。Andhowthiscomesabout,Ihaveatlargeexplainedinthe`Analyst,’andshewedinthatparticularcaseoftangents,thattherejectaneousquantitymighthavebeenafinitequantityofanygivenmagnitude,andyettheconclusionhavecomeoutexactlythesameway;and,consequently,thatthetruthofthismethoddothnotdependonthereasonassignedbytheMarquis,towit,thepostulatumforthrowingawayinfinitesimals;and,therefore,thatheandhisfollowersactedblindfold,asnotknowingthetruereasonfortheconclusionscomingoutaccuratelyright,whichIshewtohavebeentheeffectofadoubleerror。

  41。Thisisthetruthofthematter,whichyoushamefullymisrepresentanddeclaimupon,tonosortofpurposebuttoamuseandmisleadyourreader。Forwhichconductofyoursthroughoutyourremarks,youwillpardonmeifIcannototherwiseaccount,thanfromasecrethopethatthereaderofyour`Defence’wouldneverreadthe`Analyst。’

  Ifhedoth,hecannotbutseewhatanadmirablemethodyoutaketodefendyourcause:how,insteadofjustifyingthereasoning,thelogic,orthetheoryofthecasespecified,whichistherealpoint,youdiscourseofsensibleandpracticalerrors:andhowallthisisamanifestimpositionuponthereader。HemustneedsseethatIhaveexpresslysaid,``Ihavenocontroversyexceptonlyaboutyourlogicandmethod:thatIconsiderhowyoudemonstrate;whatobjectsyouareconversantabout;andwhetheryouconceivethemclearly。’’ThatIhaveoftenexpressedmyselftothesameeffect,desiringthereadertoremember,``thatIamonlyconcernedaboutthewayofcomingatyourtheorems,whetheritbelegitimateorillegitimate,clearorobscure,scientificortentative:thatIhave,onthisveryoccasion,topreventallpossibilityofmistake,repeatedandinsistedthatIconsiderthegeometricalanalystasalogician,i。e。sofarforthashereasonsandargues;andhismathematicalconclusions,notinthemselvesbutintheirpremises;notastrueorfalse,usefulorinsignificant,butasderivedfromsuchprinciples,andbysuchinferences。’’[`Analyst,’sect。20。]

  Youaffirm(andindeedwhatcanyounotaffirm?)thatthedifferencebetweenthetruesubtangentandthatfoundwithoutanycompensationisabsolutelynothingatall。Iprofessmyselfofacontraryopinion。Myreasonis,becausenothingcannotbedividedintoparts。Butthisdifferenceiscapableofbeingdividedintoany,orintomorethananygivennumberofparts;forthetruthofwhichconsulttheMarquisdel’Hospital。And,betheerrorinfactorinpracticeeversosmall,itwillnotthencefollowthattheerrorinreasoning,whichiswhatIamaloneconcernedabout,isonewhittheless,itbeingevidentthatamanmayreasonmostabsurdlyabouttheminutestthings。

  42。Prayanswermefairly,onceforall,whetheritbeyouropinionthatwhatsoeverislittleandinconsiderableenoughtoberejectedwithoutinconvenienceinpractice,thesamemayinlikemannerbesafelyrejectedandoverlookedintheoryanddemonstration。ifyousayNo,itwillthenfollowthatallyouhavebeensayinghereandelsewhere,aboutyards,andinches,anddecimalfractions,settingforthandinsistingontheextremesmallnessoftherejectaneousquantity,isquiteforeigntotheargument,andonlyapieceofskilltoimposeuponyourreader。IfyousayYes,itfollowsthatyouthengiveupatoncealltheordersoffluxionsandinfinitesimaldifferences;andsomostimprudentlyturnallyoursalliesandattacksandveteranstoyourownoverthrow。Ifthereaderisofmymind,hewilldespairofeverseeingyougetclearofthisdilemma。Thepointsincontroversyhavebeensooftenandsodistinctlynotedinthe`Analyst’thatIverymuchwonderhowyoucouldmistake,ifyouhadnomindtomistake。Itisveryplain,ifyouareinearnest,thatyouneitherunderstandmenotyourmasters。Andwhatshallwethinkofotherordinaryanalysts,whenitshallbefoundthatevenyou,wholikeachampionstepforthtodefendtheirprinciples,havenotconsideredthem?

  43。Theimpartialreaderisentreatedtoremarkthroughoutyourwholeperformancehowconfidentyouareinasserting,andwithalhowmodestinprovingorexplaining:howfrequentitiswithyoutoemployfiguresandtropesinsteadofreasons:howmanydifficultiesproposedinthe`Analyst’arediscreetlyoverlookedbyyou,andwhatstrangeworkyoumakewiththerest:howgrosslyyoumistakeandmisrepresent,andhowlittleyoupractisetheadvicewhichyousoliberallybestow。Believeme,Sir,Ihadlongandmaturelyconsideredtheprinciplesofthemodernanalysis,beforeIventuredtopublishmythoughtsthereuponinthe`Analyst。’

  And,sincethepublicationthereof,Ihavemyselffreelyconversedwithmathematiciansofallranks,andsomeoftheablestprofessors,aswellasmadeitmybusinesstobeinformedoftheopinionsofothers,beingverydesiroustohearwhatcouldbesaidtowardsclearingmydifficultiesoransweringmyobjections。But,thoughyouarenotafraidorashamedtorepresenttheanalystsasveryclearanduniformintheirconceptionofthesematters,yetIdosolemnlyaffirm(andseveralofthemselvesknowittobetrue)thatIfoundnoharmonyoragreementamongthem,butthereversethereof—thegreatestdissonance,andevencontrarietyofopinions,employedtoexplainwhatafterallseemedinexplicable。

  44。Someflytoproportionsbetweennothings。Somerejectquantitiesbecauseinfinitesimal。Othersallowonlyfinitequantities,andrejectthembecauseinconsiderable。Othersplacethemethodoffluxionsonafootwiththatofexhaustions,andadmitnothingnewtherein。

  Somemaintaintheclearconceptionoffluxions。Othersholdtheycandemonstrateaboutthingsincomprehensible。Somewouldprovethealgorismoffluxionsbyreductioadabsurdum,othersapriori。Someholdtheevanescentincrementstoberealquantities,sometobenothings,sometobelimits。

  Asmanymen,somanyminds:eachdifferingonefromanother,andallfromSirIsaacNewton。Somepleadinaccurateexpressionsinthegreatauthor,wherebytheywoulddrawhimtospeaktheirsense;notconsideringthatifhemeantastheydo,hecouldnotwantwordstoexpresshismeaning。

  Othersaremagisterialandpositive,saytheyaresatisfied,andthatisall;notconsideringthatwe,whodenySirIsaacNewton’sauthority,shallnotsubmittothatofhisdisciples。Someinsistthattheconclusionsaretrue,andthereforetheprinciples;notconsideringwhathathbeenlargelysaidinthe`Analyst’[Sect。19,20,&c。]onthathead。Lastly,several(andthosenoneofthemeanest)franklyownedtheobjectionstobeunanswerable。

  AllwhichImentionbywayofantidotetoyourfalsecolours:andthattheunprejudicedinquireraftertruthmayseeitisnotwithoutfoundationthatIcallonthecelebratedmathematiciansofthepresentagetoclearuptheseobscureanalytics,andconcuringivingtothepublicsomeconsistentandintelligibleaccountoftheirgreatMaster:foriftheydonot,Ibelievetheworldwilltakeitforgrantedthattheycannot。

  45。HavinggonethroughyourdefenceoftheBritishmathematicians,Ifind,inthenextplace,thatyouattackmeonapointofmetaphysics,withwhatsuccessthereaderwilldetermine。Ihaduponanotheroccasionmanyyearsagowroteagainstabstractgeneralideas。

  [Introductiontothe`TreatiseconcerningthePrinciplesofHumanKnowledge。’]

  Inoppositiontowhich,youdeclareyourselftoadheretothevulgaropinion—thatneithergeometrynoranyothergeneralsciencecansubsistwithoutgeneralideas(p。74)。ThisimpliesthatIholdthattherearenogeneralideas。ButIholdthedirectcontrary—thatthereareindeedgeneralideas,butnotformedbyabstractioninthemannersetforthbyMr。Locke。Tomeitisplainthereisnoconsistentideaofthelikenesswhereofmaynotreallyexist:whatsoeverthereforeissaidtobesomewhatwhichcannotexist,theideathereofmustbeinconsistent。MrLockeacknowledgethitdothrequirepainsandskilltoformhisgeneralideaofatriangle。Hefartherexpresslysaithitmustbeneitherobliquenorrectangular,neitherequilateral,equicruralnorscalenum;butallandnoneoftheseoftheseatonce。Healsosaithitisanideawhereinsomepartsofseveraldifferentandinconsistentideasareputtogether。[`EssayonHumanUnderstanding,’

  bk。iv,ch。vii,sect。9。]Allofwhichlooksverylikeacontradiction。

  But,toputthematterpastdispute,itmustbenotedthatheaffirmsittobesomewhatimperfectthatcannotexist;consequentlytheideathereofisimpossibleorinconsistent。

  46。Idesiretoknowwhetheritisnotimpossibleforanythingtoexistwhichdothnotincludeacontradiction:and,ifitis,whetherwemaynotinferthatwhatmaynotpossiblyexist,thesamedothincludeacontradiction:Ifurtherdesiretoknow,whetherthereadercanframeadistinctideaofanythingthatincludesacontradiction?Formypart,Icannot,norconsequentlyoftheabove—mentionedtriangle;thoughyou(youitseemsknowbetterthanmyselfwhatIcando)arepleasedtoassuremeofthecontrary。AgainIaskwhetherthatwhichitisabovethepowerofmantoformacompleteideaofmaynotbecalledincomprehensible?

  Andwhetherthereadercanframeacompleteideaofthisimperfectimpossibletriangle?And,ifnot,whetheritdothnotfollowthatitisincomprehensible?

  itshouldseemthatadistinctaggregateofafewconsistentpartswasnothingsodifficulttoconceiveorimpossibletoexist;andthat,therefore,yourcommentmustbewideoftheauthor’smeaning。Yougivemetounderstand(p82)thatthisaccountofageneraltrianglewasatrapwhichMr。Lockesettocatchfools。Whoiscaughtthereinletthereaderjudge。

  47。ItisMr。Locke’sopinionthateverygeneralnamestandsforageneralabstractidea,whichprescindesfromthespeciesorindividualscomprehendedunderit。Thus,forexample,accordingtohim,thegeneralnamecolourstandsforanideawhichisneitherblue,red,green,noranyparticularcolour,butsomewhatdistinctandabstractedfromthemall。Tomeitseemsthewordcolourisonlyamoregeneralnameapplicabletoallandeachoftheparticularcolours:whiletheotherspecificnames,asblue,red,green,andthelike,areeachrestrainedtoamorelimitedsignification。Thesamecanbesaidofthewordtriangle。

  Letthereaderjudgewhetherthisbenotthecase;andwhetherhecandistinctlyframesuchanideaofcolourasshallprescindfromallthespeciesthereof,orofatrianglewhichshallanswerMr。Locke’saccount,prescindingandabstractingfromalltheparticularsortsoftriangles,inthemanneraforesaid。

  48。Ientreatmyreadertothink。For,ifhedothnot,hemaybeundersomeinfluencefromyourconfidentandpositivewayoftalking。Butanyonewhothinksmay,ifImistakenot,plainlyperceivethatyouaredeluded,asitoftenhappens,bymistakingthetermsforideas。

  Nothingiseasierthantodefineintermsorwordsthatwhichisincomprehensibleinidea;forasmuchasanywordscanbeeitherseparatedorjoinedasyouplease,butideasalwayscannot。Itisaseasytosayaroundsquareasanoblongsquare,thoughtheformerbeinconceivable。Ifthereaderwillbuttakealittlecaretodistinguishbetweenthedefinitionandtheidea,betweenwordsorexpressionsandtheconceptionsofthemind,hewilljudgeofthetruthofwhatInowadvance,andclearlyperceivehowfaryouaremistakeninattemptingtoillustrateMr。Locke’sdoctrine,andwhereyourmistakelies。Or,ifthereaderismindertomakeashortwork,heneedsonlyatoncetotrywhether,layingasidethewords,hecanframeinhismindtheideaofanimpossibletriangle;uponwhichtrialtheissueofthisdisputemaybefairlyput。Thisdoctrineofabstractgeneralideasseemedtomeacapitalerror,productiveofnumberlessdifficultiesanddisputes,thatrunsnotonlythroughoutMr。Locke’sbook,butthroughmostpartsoflearning。Consequently,myanimadversionsthereuponwerenotaneffectofbeinginclinedtocarporcavilatasinglepassage,asyouwouldwrongfullyinsinuate,butproceededfromaloveoftruth,andadesiretobanish,sofarasinmelay,falseprinciplesandwrongwaysofthinking,withoutrespectofpersons。And,indeed,thoughyouandotherparty—menareviolentlyattachedtoyourrespectivemasters,yetI,whoprofessmyselfonlyattachedtotruth,seenoreasonwhyImaynotasfreelyanimadvertonMr。LockeorSirIsaacNewton,astheywouldonAristotleorDescartes。

  Certainlythemoreextensivetheinfluenceofanyerror,andthegreatertheauthoritywhichsupportsit,themoreitdeservestobeconsideredanddetectedbysincereinquirersafterknowledge。

  49。Inthecloseofyourperformance,youletmeunderstandthatyourzealfortruthandthereputationofyourmastershaveoccasionedyourreprehendingmewiththeutmostfreedom。Anditmustbeownedyouhaveshewnasingulartalenttherein。ButIamcomfortedundertheseverityofyourreprehensions,whenIconsidertheweaknessofyourarguments,which,weretheyasstrongasyourreproofs,couldleavenodoubtinthemindofthereaderconcerningthemattersindisputebetweenus。Asitis,Ileavehimtoreflectandexaminebyyourlight,howclearlyheisenabledtoconceiveafluxion,orafluxionofafluxion,apartinfinitelysmallsubdividedintoaninfinityofparts,anascentorevanescentincrement,thatwhichisneithersomethingnornothing,atriangleformedinapoint,velocitywithoutmotion,andtherestofthosearcanaofthemodernanalysis。Toconclude,Ihadsomethoughtsofadvisingyouhowtoconductyourselfforthefuture,inreturnfortheadviceyouhavesofreelyimpartedtome:but,asyouthinkitbecomesmerathertoinformmyselfthaninstructothers,Ishall,formyfartherinformation,takeleavetoproposeafewQueriestothoselearnedgentlemenofCambridge,whomyouassociatewithyourselfandrepresentasbeingequallysurprisedatthetendencyofmy`Analyst。’

  50。Idesiretoknowwhetherthosewhocanneitherdemonstratenorconceivetheprinciplesofthemodernanalysis,andyetgiveintoit,maynotbejustlysaidtohaveFaith,andbestyledbelieversofMysteries?Whetheritisimpossibletofindamongthephysicians,mechanicalphilosophers,mathematicians,andphilomathematicians,ofthepresentage,somesuchbelievers,whoyetderideChristiansfortheirbeliefofmysteries?

  Whetherwithsuchmenitisnotafair,reasonable,andlegitimatemethodtousetheargumentumadhominem?And,beingso,whetheritoughttosurpriseeitherChristiansorscholars?WhetherinanagewhereinsomanypretenderstoscienceattacktheChristianreligion,wemaynotbeallowedtomakereprisals,inordertoshewthattheirreligionofthosemenisnottobepresumedaneffectofdeepandjustthinking?Whetheranattempttodetectfalsereasonings,andremedydefectsinmathematics,oughttobeillreceivedbymathematicians?Whethertheintroducingmoreeasymethods,andmoreintelligibleprinciplesinanyscienceshouldbediscountenanced?Whethertheremaynotbefairobjectionsaswellascavils?

  Andwhethertoinquirediligentlyintothemeaningoftermsandtheproofofpropositions,notexceptingagainstanythingwithoutassigningareason,noraffectingtomistakethesignificationofwords,orstickatanexpressionwherethesensewasclear,butconsideringthesubjectinalllights,sincerelyendeavouringtofindoutanysenseormeaningwhatsoever,candidlysettingforthwhatseemsobscureandwhatfallacious,andcallinguponthosewhoprofesstheknowledgeofsuchmatterstoexplainthem;whether,Isay,suchaproceedingcanbejustlycalledcavilling?Whethertherebeanipsedixiterected?Andifso,when,where,bywhom,anduponwhatauthority?

  Whether,evenwhereauthoritywastotakeplace,onemightnothopethemathematics,atleast,wouldbeexcepted?Whetherthechiefend,inmakingmathematicssoconsiderableapartofacademicaleducation,benottoforminthemindsofyoungstudentshabitsofjustandexactreasoning?Andwhetherthestudyofabstruseandsubtlematterscanconducetothisend,unlesstheyarewellunderstood,examinedandsiftedtothebottom?Whether,therefore,thebringinggeometricaldemonstrationstotheseveresttestofreasonshouldbereckonedadiscouragementtothestudiesofanylearnedsociety?Whether,toseparatetheclearpartsofthingsfromtheobscure,todistinguishtherealprincipleswhereontruthsrest,andwhencetheyarederived,andtoproportionthejustmeasuresofassentaccordingtothevariousdegreesofevidence,beauselessorunworthyundertaking?

  Whetherthemakingmoreofanargumentthanitwillbear,andplacingitinanunduerankofevidence,benotthelikelywaytodisparageit?Whetheritmaynotbeofsomeuse,toprovokeandstirupthelearnedprofessorstoexplainapartofmathematicallearningwhichisacknowledgedtobemostprofound,difficult,andobscure,andatthesametimesetforthbyPhilalethesandmanyothersasthegreatestinstancethathaseverbeengivenoftheextentofhumanabilities?Whether,forthesakeofagreatman’sdiscoveries,wemustadopthiserrors?Lastly,whetherinanagewhereinallotherprinciplesarecanvassedwiththeutmostfreedom,theprinciplesofFluxionsaretobealoneexcepted?AnAppendixconcerningMr。Walton’sVindicationofSirIsaacNewton’sPrinciplesofFluxions。1。Ihadnosoonerconsideredtheperformanceof`Philalethes,’

  butMr。Walton’s`VindicationofFluxions’wasputintomyhands。AsthisDublinprofessorgleansafterthe`Cantabrigian,’onlyendeavouringtotranslateafewpassagesfromSirIsaacNewton’s`Principia,’andenlargeonahintortwoof`Philalethes,’hedeservesnoparticularnotice。Itmaysufficetoadvertisethereaderthattheforegoing`Defence’containsafullandexplicitanswertoMr。Walton,ashewillfind,ifhethinksitworthhispainstoreadwhatthisgentlemanhathwritten,andcompareittherewith:particularlywithsect。18,20,30,32—36,43。Itisnot,Iamsure,worthminetorepeatthesamethings,orconfutethesamenotionstwiceover,inmereregardtoawriterwhohathcopiedeventhemannersof`Philalethes,’andwhominansweringtheotherIhave,ifIamnotmuchmistakensufficientlyanswered。

  2。Mr。Waltontouchesonthesamepointsthattheotherhadtoucheduponbeforehim。Hepursuesahintwhichtheotherhadgiven[`Philalethes,’p。32。]aboutSirIsaac’sfirstsectionconcerningtherationesprimaeetultimae。Hediscreetlyavoids,liketheother,tosayonesyllableofsecond,third,orfourthfluxions,andofdiversotherpointsmentionedinthe`Analyst,’aboutallwhichIobserveinhimamostprudentandprofoundsilence。Andyetheverymodestlygiveshisreadertounderstandthatheisabletoclearupalldifficultiesandobjectionsthathaveeverbeenmade(p。5)。Mr。Walton,inthebeginning,like`Philalethes,’

  fromaparticularcasemakesageneralinference;supposingthatInfidelitytobeimputedtomathematiciansingeneralwhichIsupposeonlyinthepersontowhomthe`Analyst’wasaddressed,andcertainotherpersonsofthesamemindwithhim。Whetherthisextraordinarywayofreasoningbethecauseoreffectofhispassion,Iknownot:butbeforeIhadgottotheendofhis`Vindication,’Iceasedtobesurprisedathislogicandhistemperinthebeginning。Thedoubleerror,whichinthe`Analyst’wasplainlymeanttobelongtoothers,hewith`Philalethes’(whoseveryoversightheadopts)supposethtohavebeenascribedtoSirIsaacNewton(p。36)。

  Andthiswriteralso,aswellasthe`Cantabrigian,’mustneedstakeuponhimtoexplainthemotiveofmywritingagainstfluxions;whichhegivesout,withgreatassurance,tohavebeenbecauseSirIsaacNewtonhadpresumedtointerposeinpropheciesandrevelations,andtodecideinreligiousaffairs(p。4);whichissofarfrombeingtruethat,onthecontrary,Ihaveahighvalueforthoselearnedremainsofthatgreatman,whoseoriginalandfreegeniusisaneternalreproachtothattribeoffollowers,whoarealwaysimitatingbutneverresemblehim。ThisspecimenofMr。Walton’struthwillbeawarningtothereadertousehisowneyes,andinobscurepointsnevertotrustthegentleman’scandour,whodarestomisrepresenttheplainest。

  3。Iwasthinkingtohavesaidnomoreconcerningthisauthor’sperformance,but,lestheshouldimaginehimselftoomuchneglected,Ientreatthereadertohavethepatiencetoperuseit;andifhefindsanyonepointinthedoctrineoffluxionsclearedup,oranyoneobjectioninthe`Analyst’answered,orsomuchasfairlystated,lethimthenmakehiscomplimentstotheauthor。But,ifhecannomoremakesenseofwhatthisgentlemanhaswrittenthanIcan,hewillneednoanswertoit。Nothingiseasierthanforamantotranslate,orcopy,orcomposeaplausiblediscourseofsomepagesintechnicalterms,wherebyheshallmakeashowofsayingsomewhat,althoughneitherthereadernorhimselfunderstandonetittleofit。WhetherthisbethecaseofMr。Walton,andwhetherheunderstandseitherSirIsaacNewton,orme,orhimself(whateverImaythink),Ishallnottakeituponmetosay。ButonethingIknow,thatmanyanunmeaningspeechpassethforsignificantbythemereassuranceofthespeaker,tillhecomethtobecatechizeduponit;andthenthetruthshowethitself。ThisVindicator,indeed,byhisdissemblingninepartsintenofthedifficultiesproposedinthe`Analyst,’shewethnoinclinationtobecatechizedbyme。Buthisscholarshavearighttobeinformed。I

  thereforerecommendittothemnottobeimposedonbyhardwordsandmagisterialassertions,butcarefullytopryintohissense,andsifthismeaning,andparticularlytoinsistonadistinctanswertothefollowingQuestions。

  4。Letthemaskhim,whetherhecanconceivevelocitywithoutmotion,ormotionwithoutextension,orextensionwithoutmagnitude?

  Ifheanswersthathecan,lethimteachthemtodothesame。Ifhecannot,lethimbeasked,howhereconcilestheideaofafluxionwhichhegives(p。13)withcommonsense?—Again,lethimbeasked,Whethernothingbenottheproductofnothingmultipliedbysomething;and,ifso,whenthedifferencebetweenthegnomenandthesumoftherectangles[See`Vindication,’

  p。17。]vanisheth,whethertherectanglesthemselvesdonotvanish?i。e。whenabisnothing,whetherAbBabenotalsonothing?i。e。whetherthemomentumofABbenotnothing?—Lethimthenbeasked,whathismomentumsaregoodfor,whentheyarethusbroughttonothing?—Again,Iwishhewereaskedtoexplainthedifferencebetweenamagnitudeinfinitelysmallandamagnitudeinfinitelydiminished。Ifhesaith,thereisnodifference,thenlethimbefartherasked,howhedarestoexplainthemethodoffluxions,bytheratioofmagnitudesinfinitelydiminished(p。9),whenSirIsaacNewtonhathexpresslyexcludedallconsiderationofquantitiesinfinitelysmall?[Seehis`IntroductiontotheQuadratures。’]Ifthisablevindicatorshouldsaythatquantitiesinfinitelydiminishedarenothingatall,andconsequentlythat,accordingtohim,thefirstandlastratiosareproportionsbetweennothings,lethimbedesiredtomakesenseofthis,orexplainwhathemeansby``proportionbetweennothings,’’Ifheshouldsay,theultimateproportionsaretheratiosofmerelimits,thenlethimbeaskedhowthelimitsoflinescanbeproportionedordivided?Afterall,whoknowsbutthisgentleman,whohathalreadycomplainedofmeforanuncommonwayoftreatingmathematicsandmathematicians(p。5),may(aswellasthe`Cantabrigian’)cryout``SpainandtheInquisition!’’whenhefindshimselfthuscloselypursuedandbesetwithinterrogatories?Thatwemaynot,therefore,seemtoohardonaninnocentman,whoprobablymeantnothing,butwasbetrayedbyfollowinganotherintodifficultiesandstraitsthathewasnotawareof,Ishallproposeonesingleexpedient,bywhichhisdisciples(whomitmostconcerns)

  maysoonsatisfythemselveswhetherthisVindicatorreallyunderstandswhathetakesuponhimtovindicate。Itis,inshort,thattheywouldaskhimtoexplainthesecond,third,orfourthfluxionsuponhisprinciples。

  Bethisthetouchstoneofhis`Vindication。’Ifhecandoit,Ishallownmyselfmuchmistaken:ifhecannot,itwillbeevidentthathewasmuchmistakeninhimself,whenhepresumedtodefendfluxionswithoutsomuchasknowingwhattheyare。So,havingputthemeritsofthecauseonthisissue,Ileavehimtobetriedbyhisscholars。

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