ThedifferencebetweentheWhigandtheRadicaltempershoweditselfinphilosophicalasinpoliticalquestions。TheRadicalpridedhimselfonbeinglogicalandthoroughgoing，whiletheWhiglovedcompromise，andthoughtthatlogicwasveryapttobeanuisance。ThesystematicreticencewhichtheUtilitariansheldtobenecessarypreventedthiscontrastfromshowingitselfdistinctlyonthesurface。TheUtilitarians，however，thoughtheyavoidedsuchoutspokenscepticismaswouldstartlethepublic，indicatedquitesufficientlytotheinitiatedtheiressentialposition。Itimpliedwhattheyfullyrecognisedinprivateconversation——acompleteabandonmentoftheology。Theylefttheobviousinferencestobedrawnbyothers。Inphilosophytheycouldspeakoutinawell-foundedconfidencethatfewpeoplewereabletodrawinferences。Iwillbeginbyconsideringthedoctrineagainstwhichtheyprotested；fortheantagonismreveals，Ithink，thekeytotheirposition。
　　WhenStewartwasobligedbyinfirmitytoretirefromtheactivedischargeofhisduties，hewassucceededbyThomasBrown1778-1820。Brownhadshownearlyprecocity，andattheageoffifteenhadattractedStewart’snoticebysomeremarksonapsychologicalpoint。HepublishedattwentyacriticismofDarwin’sZoonomia，andhebecameoneoftheEdinburghReviewcircle。
　　WhentheReviewwasstartedhecontributedanarticleuponKant。
　　InthosehappydaysitwassofarfromnecessarytoprepareoneselfforsuchataskbystudyingalibraryofcommentatorsthattheyoungreviewercouldfranklyadmithiswholeknowledgetobederivedfromVillers’PhilosophiedeKant1801。3Soonafterwardshetookanimportantshareinaoncefamouscontroversy。JohnLeslie，justelectedtothemathematicalchairatEdinburgh，wasaccusedofhavingwrittenfavourablyofHume’stheoryofcausation。WhigsandToriestookthisupasapartyquestion，4andBrownundertooktoexplaininapamphletwhatHume’stheorywas，andtoshowthatitdidnotleadtoatheism。Leslie’sfriendstriumphed，thoughitdoesnotappearhowfarBrown’sargumentscontributedtotheirsuccess。
　　Thepamphletwasrewrittenandenlarged，andathirdeditionof1818givesafullexpositionofhistheory。BrownhadmeanwhilebecomeStewart’sleadingdisciple，andin1810waselectedtobehiscolleague，Brownheldtheposition，doingalltheactiveduties，untilhisprematuredeathin1820。Brown，accordingtohisbiographer，wrotehislecturesimmediatelybeforedelivery，andcompletedthemduringhisfirsttwoyearsofoffice。Histheories，aswellashiswords，wereoften，accedingtothesameauthority，extemporised。
　　Brownfoundthathecouldnotimprovewhathehadwrittenunder’verypowerfulexcitement。’Moreover，hehadanunluckybeliefthathewasapoet。From1814till1819hebroughtoutyearlywhathesupposedtobeapoem，theseproductions，theParadiseofCoquetsandtherest，areintheold-fashionedtaste，andhavelongpassedintooblivion。
　　Thelectures，publishedposthumously，becameatextbookforstudents，andreachedanineteentheditionin1851。
　　Theirfaults，consideredasphilosophicaltreatises，arepalpable，theyhavethewordinessofhastycomposition，andthediscursiverhetoricintendedtocatchtheattentionofanindolentaudience。Browndoesnotseethatheisinsultinghishearerswhenheapologisesforintroducinglogicintolecturesuponmetaphysics，andindemnifiesthembyquotationsfromAkensideandtheEssayonMan。Brown，however，showedgreatacutenessandoriginality。Hemadedeviations，andtookpainstomarkhisdeviations，fromReid，thoughhespokemoreguardedlyofhisownfriend，Stewart，Stewart，whohadstronglysupportedBrown’selection，wasshockedwhen，onthepublicationofthelectures，hecametodiscoverthathiscolleaguehadbeenpreachingheresy，andwrotewithobviousannoyanceofBrown’shastinessanddangerousconcessionstotheenemy。5Brown，however，impressedhiscontemporariesbyhisability。SydneySmithisprobablyreportingthecurrentjudgmentofhisowncirclewhenhesays6thatinmetaphysicsStewartwasa’humbug’comparedwithBrown，IcertainlythinkthatStewart，whomIshouldbesorrytocallahumbug，showslessvigourandsubtlety。Brown，atanyrate，impressedboththeMills，andhisrelationtothemissignificant。
　　Brown’sEssayuponCausationindicatesthisrelation。Inthis，indeed，thereislittle，ifany，divergencefromStewart，thoughheattacksReidwithconsiderableasperity。HeurgesthatReid，whilereallyagreeingwithHume，affectedtoanswerhimundercoverofmerelyverbaldistinctions。7Themainpointissimple。
　　Humehadassertedthatalleventsseemtobe’entirelylooseandseparate，’
　　or，inotherwords，’conjoinedbutneverconnected。’Yethepointsoutthat，infact，whenwehavefoundtwoeventstobe’conjoined，’wecallonecauseandtheothereffect，andassumea’necessaryconnection’betweenthem。Hethenasks，Whatistheoriginofthisbelief，andwhat，therefore，isthelogicalwarrantforitsvalidity?BrownentirelyacceptsHume’sstatementofthefacts。Therealmeaningofourstatementsisevadedbyappealingtotheconceptionof’power。’Whentheloadstoneinhisfavouriteillustrationattractstheiron，wesayithasa’power’ofattractingiron。Buttospeakthusofapowerissimplytodescribethesamefactsinotherwords。Weassertthis，andnothingmorethanthis，thatwhentheloadstonecomesneartheiron，eachmovestowardstheother。’Power’isawordwhichonlycoversastatementof’invariableantecedence。’Browntracesthevariousconfusionswhichhaveobscuredthetruenatureofthisbelief。Heinsistsespeciallythatwecannomorediscoverpowerinmentalthaninphysicalsequences。Thewillhadbeensupposedtobethetypeofcausalpower；butvolition，accordingtoBrown，revealssimplyanothersuccessionofdesiresandbodilyactions。Thehypothesisof’power’hasbeenreallythesourceof’illusion。’Thetendencytopersonifyleadsustoconvertmetaphorintofact，toinventasubjectofthisimaginary’power，’
　　andthustocreateamythologyofbeingstocarryontheprocessesofnature。
　　Inotherwords，BrownherefollowsHumeorevenanticipatesComte。AsJ。
　　S。Millremarks，8thiserroneousidentificationof’power’with’will’givesthe’psychologicalrationaleofComte’sgreathistoricalgeneralisation’；
　　and，sofar，Brown，asafollowerofHume，isclearlyonthewaytopositivism。
　　Theworld，then，isavastaggregateof’loose’phenomena。Acontemplationofthingsrevealsnoreasonforoneorderratherthananother。Youmaylookatyourloadstoneaslongasyouplease，butyouwillfindnoreasonforitsattractingiron。Youmayindeedinterpolateanumberofminuteinterveningsequences，andtheprocessoftensuggestsavaguesomethingmorethansequence；butthisisamereillusion。9Couldwe，infact，seealltheminutechangesinbodiesweshouldactuallyperceivethatcausemeansnothingbut’theimmediateinvariableantecedenceofanevent。’10Brownespeciallyarguesagainsttheattemptsofd’AlembertandEulertodeducethefirstlawsofmotionfromtheprincipleof’sufficientreason。’11That，ashearguesindetail，ismerelybeggingthequestion，byintroducingtheprincipleofcausationunderanalias。
　　What，then，istheprinciple?
　　Webelieve，hesays，12that’everyeventmusthaveacause，’
　　andthatcircumstancesexactly’similarmusthaveresultsexactlysimilar。’
　　Thisbelief，thoughapplicabletoallevents，doesnotgiveusthe’slightestaid’todetermining，independentlyofexperience，anyparticularevent。
　　WeobservethatBfollowsA，but，forallwecansay，itmightaswellfollowanyotherletterofthealphabet。Yetweareentitledtosayingeneralthatitdoesuniformlyfollowsomeparticularletter。Themetaphorwhichdescribescauseandeffectasa’bond’tyingAandBtogetherisperfectlyappropriateiftakentoexpressthebarefactofsequence；13butwefallintoerrorifwefancythereisreallyanybondwhateverbesidetheeventsthemselves。
　　Thebelief，then，incausationhaspreciselythesameimportaccordingtoHumeandBrown；andbothagreethatitisnotproducedby’reasoning。’Theproposition’BhasoncesucceededA，’or’hassucceededAathousandtimes，’isentirelydifferentfromtheproposition’BwillforeversucceedA。’14Noprocessoflogicalinferencecanextractonefromtheother。Shallwe，then，giveupabeliefincausation?Thebeliefinanycaseexistsasafact。Humeexplainsitbycustomorassociation。Brownargues，andIthinkwithmuchforce，thatHume’sexplanationisinsufficient。Associationmayexplainifitdoesmorethanrestatethefactthatone’idea’callsupanotheridea，butsuchassociationmayandoftendoesoccurwithoutsuggestinganybelief。
　　Thebelief，too，precedestheassociation。Webeginbybelievingtoomuch，nottoolittle，andassumeanecessaryconnectionofmanyphenomenawhichweafterwardsfindtobeindependent。Thetrueansweristhereforedifferent。
　　Therearethreesourcesofbelief，’perception，’’reasoning，’and’intuition。’15Now，wecannot’perceive’anythingbutapresentcoincidence；neithercanweestablishaconnectionbyanyprocessof’reasoning，’andthereforethebeliefmustbean’intuition。’This，accordingly，isBrown’sconclusion。
　　’Thereareprinciples，’hesays，’independentofreasoning，inthemindwhichsaveitfromtheoccasionalfolliesofallourratiocinations’；16orrather，asheexplains，whichunderlieallreasoning。Thedifference，then，betweenHumeandBrownand，asBrownargues，betweenHumeandReid’srealdoctrineisnotastotheimport，butastotheorigin，ofthebelief。
　　Itisan’intuition’simplybecauseitcannotbefurtheranalysed。Itdoesnotallowustopassasinglestepbeyondexperience；itmerelyauthorisesustointerpretexperience。Wecandiscoveranyactuallawofconnectionbetweenphenomenaonlybyobservingthattheyoccurinsuccession。Wecannotgetbeyondorbehindthefacts——andthereforeintuitionisminthissenseisnotopposedtoempiricism，butawarrantforempiricalconclusions。
　　An’intuition，’briefly，isanunanalysablebelief。Brownassertsthatacertainelementofthoughthasnotbeenexplained，andassumesittobethereforeinexplicableorultimate。Brown’saccountofcausationhadagreatinfluenceuponboththeMills，andespeciallyaffectedtheteachingoftheyoungerMill。
　　Anotherpointisimportant。
　　Reid，asIhavesaid，hadspecifypridedhimselfuponhissupposedoverthrowofBerkeley’sidealism。Hewasconsideredtohaveshown，inspiteofsceptics，thatthecommonbeliefinanexternalworldwasreasonable。BrowninhislecturesridiculedReid’sclaim。This’mightyachievement，’the’supposedoverthrowofagreatsystem，’was’nothingmorethantheproofthatcertainphrasesaremetaphorical，whichwereintendedbytheirauthorstobeunderstoodonlyasmetaphors。’17ThetheorywasdeadbeforeReidslewit，thoughthephraseswerestillusedasamere’relic，’orsurvivalofanobsoletedoctrine。18TheimpossibilityofconstructingextensionoutofoursensationsistheexperimentumcrucisuponwhichReidwasreadytostakehiscase。Iftheattemptatsuchaconstructioncouldsucceed，hewould’layhishanduponhismouth’andgiveuptheargument。19Browntakesupthechallengethusthrownout。HeholdsthatourknowledgeofanexternalworldisderivedfromasourcewhichReidoverlooked。HemodifiestheScottishpsychologybyintroducingthemuscularsenses。Histheoryisthattheinfantwhichhaslearnedtomovediscoversthatonsomeoccasionsitsmovementsaremodifiedbyasenseof’impededeffort。’20Thesuddeninterruptiontoawell-knownseriesexcitesinitsmindthenotionof’acausewhichisnotinitself。’Thisisthesourceofourbeliefinanexternalworld。Thatbeliefisessentiallythebeliefinsomecausewhichweknowtobeotherthanourownmentalconstitutionortheseriesof’internal’phenomena，andofwhichwecanknownothingelse。Itisenoughtoindicateatheorywhichhasbeenelaboratedbylaterpsychologists，andplaysagreatpartforexampleinthetheoriesofMill，Bain，andMr。HerbertSpencer。ItshowstherealtendencyofBrown’sspeculations。