OftheeffectsofotherrelationsandotherHabits。
Howeverconvincingtheforegoingargumentsmayappear，wemustnotrestcontentedwiththem，butmustturnthesubjectoneveryside，inordertofindsomenewpointsofview，fromwhichwemayillustrateandconfirmsuchextraordinary，andsuchfundamentalprinciples。Ascrupuloushesitationtoreceiveanynewhypothesisissolaudableadispositioninphilosophers，andsonecessarytotheexaminationoftruth，thatitdeservestobecomply’dwith，andrequiresthateveryargumentbeproduc’d，whichmaytendtotheirsatisfaction，andeveryobjectionremov’d，whichmaystopthemintheirreasoning。
Ihaveoftenobserv’d，that，besidecauseandeffect，thetworelationsofresemblanceandcontiguity，aretobeconsider’dasassociatingprinciplesofthought，andascapableofconveyingtheimaginationfromoneideatoanother。Ihavealsoobserv’d，thatwhenoftwoobjectsconnectedto-etherbyanyoftheserelations，oneisimmediatelypresenttothememoryorsenses，notonlythemindisconvey’dtoitsco-relativebymeansoftheassociatingprinciple；butlikewiseconceivesitwithanadditionalforceandvigour，bytheunitedoperationofthatprinciple，andofthepresentimpression。AllthisIhaveobserv’d，inordertoconfirmbyanalogy，myexplicationofourjudgmentsconcerningcauseandeffect。Butthisveryargumentmay，perhaps，beturn’dagainstme，andinsteadofaconfirmationofmyhypothesis，maybecomeanobjectiontoit。Foritmaybesaid，thatifallthepartsofthathypothesisbetrue，viz。thatthesethreespeciesofrelationarederiv’dfromthesameprinciples；thattheireffectsininformingandenliveningourideasarethesame；andthatbeliefisnothingbutamoreforcibleandvividconceptionofanidea；itshou’dfollow，thatthatactionofthemindmaynotonlybederiv’dfromtherelationofcauseandeffect，butalsofromthoseofcontiguityandresemblance。Butaswefindbyexperience，thatbeliefarisesonlyfromcausation，’andthatwecandrawnoinferencefromoneobjecttoanother，excepttheybeconnectedbythisrelation，wemayconclude，thatthereissomeerrorinthatreasoning，whichleadsusintosuchdifficulties。
Thisistheobjection；letusnowconsideritssolution。’Tisevident，thatwhateverispresenttothememory，strikinguponthemindwithavivacity，whichresemblesanimmediateimpression，mustbecomeofconsiderablemomentinalltheoperationsofthemind，andmusteasilydistinguishitselfabovethemerefictionsoftheimagination。Oftheseimpressionsorideasofthememoryweformakindofsystem，comprehendingwhateverweremembertohavebeenpresent，eithertoourinternalperceptionorsenses；andeveryparticularofthatsystem，join’dtothepresentimpressions，wearepleas’dtocallareality。Butthemindstopsnothere。Forfinding，thatwiththissystemofperceptions，thereisanotherconnectedbycustom，orifyouwill，bytherelationofcauseoreffect，itproceedstotheconsiderationoftheirideas；andasitfeelsthat’tisinamannernecessarilydeterminedtoviewtheseparticularideas，andthatthecustomorrelation，bywhichitisdetermined，admitsnotoftheleastchange，itformsthemintoanewsystem，whichitlikewisedignifieswiththetitleofrealities。Thefirstofthesesystemsistheobjectofthememoryandsenses；thesecondofthejudgment。
’Tisthislatterprinciple，whichpeoplestheworld，andbringsusacquaintedwithsuchexistences，asbytheirremovalintimeandplace，liebeyondthereachofthesensesandmemory。BymeansofitIpainttheuniverseinmyimagination，andfixmyattentiononanypartofitIplease。IformanideaofRome，whichIneitherseenorremember；butwhichisconnectedwithsuchimpressionsasIremembertohavereceivedfromtheconversationandbooksoftravellersandhistorians。ThisideaofRomeIplaceinacertainsituationontheideaofanobject，whichIcalltheglobe。Ijointoittheconceptionofaparticulargovernment，andreligion，andmanners。Ilookbackwardandconsideritsfirstfoundation；itsseveralrevolutions，successes，andmisfortunes。Allthis，andeverythingelse，whichIbelieve，arenothingbutideas；tho’bytheirforceandsettledorder，arisingfromcustomandtherelationofcauseandeffect，theydistinguishthemselvesfromtheotherideas，whicharemerelytheoffspringoftheimagination。
Astotheinfluenceofcontiguityandresemblance，wemayobserve，thatifthecontiguousandresemblingobjectbecomprehendedinthissystemofrealities，thereisnodoubtbutthesetworelationswillassistthatofcauseandeffect，andinfixtherelatedideawithmoreforceintheimagination。ThisIshallenlargeuponpresently。MeanwhileIshallcarrymyobservationastepfarther，andassert，thatevenwheretherelatedobjectisbutfeign’d，therelationwillservetoenliventheidea，andencreaseitsinfluence。Apoet，nodoubt，willbethebetterabletoformastrongdescriptionoftheElysianfields，thathepromptshisimaginationbytheviewofabeautifulmeadoworgarden；asatanothertimehemaybyhisfancyplacehimselfinthemidstofthesefabulousregions，thatbythefeign’dcontiguityhemayenlivenhisimagination。
Buttho’Icannotaltogetherexcludetherelationsofresemblanceandcontiguityfromoperatingonthefancyinthismanner，’tisobservablethat，whensingle，theirinfluenceisveryfeebleanduncertain。Astherelationofcauseandeffectisrequisitetopersuadeusofanyrealexistence，soisthispersuasionrequisitetogiveforcetotheseotherrelations。Forwhereupontheappearanceofanimpressionwenotonlyfeignanotherobject，butlikewisearbitrarily，andofourmeregood-willandpleasuregiveitaparticularrelationtotheimpression，thiscanhavebutasmalleffectuponthemind；noristhereanyreason，why，uponthereturnofthesameimpression，weshou’dbedeterminedtoplacethesameobjectinthesamerelationtoit。Thereisnomannerofnecessityforthemindtofeignanyresemblingandcontiguousobjects；andifitfeignssuch，thereisaslittlenecessityforitalwaystoconfineitselftothesame，withoutanydifferenceorvariation。Andindeedsuchafictionisfoundedonsolittlereason，thatnothingbutpurecapricecandeterminethemindtoformit；andthatprinciplebeingfluctuatinganduncertain，’tisimpossibleitcaneveroperatewithanyconsiderabledegreeofforceandconstancy。Themindforseesandanticipatesthechange；andevenfromtheveryfirstinstantfeelstheloosenessofitsactions，andtheweakholdithasofitsobjects。Andasthisimperfectionisverysensibleineverysingleinstance，itstillencreasesbyexperienceandobservation，whenwecomparetheseveralinstanceswemayremember，andformageneralruleagainstthereposinganyassuranceinthosemomentaryglimpsesoflight，whichariseintheimaginationfromafeign’dresemblanceandcontiguity。
Therelationofcauseandeffecthasalltheoppositeadvantages。Theobjectsitpresentsarefixtandunalterable。Theimpressionsofthememoryneverchangeinanyconsiderabledegree；andeachimpressiondrawsalongwithitapreciseidea，whichtakesitsplaceintheimaginationassomethingsolidandreal，certainandinvariable。Thethoughtisalwaysdetermin’dtopassfromtheimpressiontotheidea，andfromthatparticularimpressiontothatparticularidea，withoutanychoiceorhesitation。
Butnotcontentwithremovingthisobjection，Ishallendeavourtoextractfromitaproofofthepresentdoctrine。Contiguityandresemblancehaveaneffectmuchinferiortocausation；butstillhavesomeeffect，andaugmenttheconvictionofanyopinion，andthevivacityofanyconception。Ifthiscanbeprov’dinseveralnewinstances，besidewhatwehavealreadyobserv’d，’twillbeallow’dnoinconsiderableargument，thatbeliefisnothingbutalivelyidearelatedtoapresentimpression。
Tobeginwithcontiguity；ithasbeenremark’damongtheMahometansaswellasChristians，thatthosepilgrims，whohaveseenMECCAortheHOLYLAND，areeveraftermorefaithfulandzealousbelievers，thanthosewhohavenothadthatadvantage。Aman，whosememorypresentshimwithalivelyimageoftheRed-Sea，andtheDesert，andJerusalem，andGalilee，canneverdoubtofanymiraculousevents，whicharerelatedeitherbyMosesortheEvangelists。Thelivelyideaoftheplacespassesbyaneasytransitiontothefacts，whicharesuppos’dtohavebeenrelatedtothembycontiguity，andencreasesthebeliefbyencreasingthevivacityoftheconception。Theremembranceofthesefieldsandrivershasthesameinfluenceonthevulgarasanewargument；andfromthesamecauses。
Wemayformalikeobservationconcerningresemblance。Wehaveremark’d，thattheconclusion，whichwedrawfromapresentobjecttoitsabsentcauseoreffect，isneverfoundedonanyqualities，whichweobserveinthatobject，consider’dinitself，or，inotherwords，that’tisimpossibletodetermine，otherwisethanbyexperience，whatwillresultfromanyphenomenon，orwhathasprecededit。Buttho’thisbesoevidentinitself，thatitseem’dnottorequireany，proof；yetsomephilosophershaveimagin’dthatthereisanapparentcauseforthecommunicationofmotion，andthatareasonablemanmightimmediatelyinferthemotionofonebodyfromtheimpulseofanother，withouthavingrecoursetoanypastobservation。Thatthisopinionisfalsewilladmitofaneasyproof。Forifsuchaninferencemaybedrawnmerelyfromtheideasofbody，ofmotion，andofimpulse，itmustamounttoademonstration，andmustimplytheabsoluteimpossibilityofanycontrarysupposition。Everyeffect，then，besidethecommunicationofmotion，impliesaformalcontradiction；and’tisimpossiblenotonlythatitcanexist，butalsothatitcanbeconceiv’d。Butwemaysoonsatisfyourselvesofthecontrary，byformingaclearandconsistentideaofonebody’smovinguponanother，andofitsrestimmediatelyuponthecontact，orofitsreturningbackinthesamelineinwhichitcame；orofitsannihilation；orcircularorellipticalmotion:andinshort，ofaninfinitenumberofotherchanges，whichwemaysupposeittoundergo。Thesesuppositionsareallconsistentandnatural；andthereason，Whyweimaginethecommunicationofmotiontobemoreconsistentandnaturalnotonlythanthosesuppositions，butalsothananyothernaturaleffect，isfoundedontherelationofresemblancebetwixtthecauseandeffect，whichishereunitedtoexperience，andbindstheobjectsintheclosestandmostintimatemannertoeachother，soastomakeusimaginethemtobeabsolutelyinseparable。Resemblance，then，hasthesameoraparallelinfluencewithexperience；andastheonlyimmediateeffectofexperienceistoassociateourideastogether，itfollows，thatallbeliefarisesfromtheassociationofideas，accordingtomyhypothesis。
’Tisuniversallyallow’dbythewritersonoptics，thattheeyeatalltimesseesanequalnumberofphysicalpoints，andthatamanonthetopofamountainhasnolargeranimagepresentedtohissenses，thanwhenheiscoop’dupinthenarrowestcourtorchamber。’Tisonlybyexperiencethatheinfersthegreatnessoftheobjectfromsomepeculiarqualitiesoftheimage；andthisinferenceofthejudgmentheconfoundswithsensation，asiscommononotheroccasions。Now’tisevident，thattheinferenceofthejudgmentisheremuchmorelivelythanwhatisusualinourcommonreasonings，andthatamanhasamorevividconceptionofthevastextentoftheoceanfromtheimagehereceivesbytheeye，whenhestandsonthetopofthehighpromontory，thanmerelyfromhearingtheroaringofthewaters。Hefeelsamoresensiblepleasurefromitsmagnificence；whichisaproofofamorelivelyidea:Andheconfoundshisjudgmentwithsensation，whichisanotherproofofit。Butastheinferenceisequallycertainandimmediateinbothcases，thissuperiorvivacityofourconceptioninonecasecanproceedfromnothingbutthis，thatindrawinganinferencefromthesight，besidethecustomaryconjunction，thereisalsoaresemblancebetwixttheimageandtheobjectweinfer；whichstrengthenstherelation，andconveysthevivacityoftheimpressiontotherelatedideawithaneasierandmorenaturalmovement。
NoweaknessofhumannatureismoreuniversalandconspicuousthanwhatwecommonlycallCREDULITY，oratooeasyfaithinthetestimonyofothers；andthisweaknessisalsoverynaturallyaccountedforfromtheinfluenceofresemblance。Whenwereceiveanymatteroffactuponhumantestimony，ourfaitharisesfromtheverysameoriginasourinferencesfromcausestoeffects，andfromeffectstocauses；noristhereanythingbutourexperienceofthegoverningprinciplesofhumannature，whichcangiveusanyassuranceoftheveracityofmen。Buttho’experiencebethetruestandardofthis，aswellasofallotherjudgments，we。seldomregulateourselvesentirelybyit；buthavearemarkablepropensitytobelievewhateverisreported，evenconcerningapparitions，enchantments，andprodigies，howevercontrarytodailyexperienceandobservation。Thewordsordiscoursesofothershaveanintimateconnexionwithcertainideasintheirmind；andtheseideashavealsoaconnexionwiththefactsorobjects，whichtheyrepresent。Thislatterconnexionisgenerallymuchover-rated，andcommandsourassentbeyondwhatexperiencewilljustify；whichcanproceedfromnothingbesidetheresemblancebetwixttheideasandthefacts。Othereffectsonlypointouttheircausesinanobliquemanner；butthetestimonyofmendoesitdirectly，andistobeconsideredasanimageaswellasaneffect。Nowonder，therefore，wearesorashindrawingourinferencesfromit，andarelessguidedbyexperienceinourjudgmentsconcerningit，thaninthoseuponanyothersubject。
Asresemblance，whenconjoin’dwithcausation，fortifiesourreasonings；sothewantofitinanyverygreatdegreeisablealmostentirelytodestroythem。Ofthisthereisaremarkableinstanceintheuniversalcarelessnessandstupidityofmenwithregardtoafuturestate，wheretheyshowasobstinateanincredulity，astheydoablindcredulityonotheroccasions。Thereisnotindeedamoreamplematterofwondertothestudious，andofregrettothepiousman，thantoobservethenegligenceofthebulkofmankindconcerningtheirapproachingcondition；and’tiswithreason，thatmanyeminenttheologianshavenotscrupledtoaffirm，thattho’thevulgarhavenoformalprinciplesofinfidelity，yettheyarereallyinfidelsintheirhearts，andhavenothinglikewhatwecancallabeliefoftheeternaldurationoftheirsouls。Forletusconsiderontheonehandwhatdivineshavedisplay’dwithsucheloquenceconcerningtheimportanceofeternity；andatthesametimereflect，thattho’inmattersofrhetoricweoughttolayouraccountwithsomeexaggeration，wemustinthiscaseallow，thatthestrongestfiguresareinfinitelyinferiortothesubject:Andafterthisletusviewontheotherhand，theprodigioussecurityofmeninthisparticular:Iask，ifthesepeoplereallybelievewhatisinculcatedonthem，andwhattheypretendtoaffirm；andtheanswerisobviouslyinthenegative。Asbeliefisanactofthemindarisingfromcustom，’tisnotstrangethewantofresemblanceshou’doverthrowwhatcustomhasestablished，anddiminishtheforceoftheidea，asmuchasthatlatterprincipleencreasesit。Afuturestateissofarremov’dfromourcomprehension，andwehavesoobscureanideaofthemanner，inwhichweshallexistafterthedissolutionofthebody，thatallthereasonswecaninvent，howeverstronginthemselves，andhowevermuchassistedbyeducation，areneverablewithslowimaginationstosurmountthisdifficulty，orbestowasufficientauthorityandforceontheidea。Iratherchoosetoascribethisincredulitytothefaintideaweformofourfuturecondition，deriv’dfromitswantofresemblancetothepresentlife，thantothatderiv’dfromitsremoteness。ForIobserve，thatmenareeverywhereconcern’daboutwhatmayhappenaftertheirdeath，provideditregardthisworld；andthattherearefewtowhomtheirname，theirfamily，theirfriends，andtheircountryarein。anyperiodoftimeentirelyindifferent。
Andindeedthewantofresemblanceinthiscasesoentirelydestroysbelief，thatexceptthosefew，whouponcoolreflectionontheimportanceofthesubject，havetakencarebyrepeatedmeditationtoimprintintheirmindstheargumentsforafuturestate，therescarceareany，whobelievetheimmortalityofthesoulwithatrueandestablishedjudgment；suchasisderiv’dfromthetestimonyoftravellersandhistorians。Thisappearsveryconspicuouslywherevermenhaveoccasiontocomparethepleasuresandpains，therewardsandpunishmentsofthislifewiththoseofafuture；eventho’thecasedoesnotconcernthemselves，andthereisnoviolentpassiontodisturbtheirjudgment。TheRomanClatholicksarecertainlythemostzealousofanysectintheChristianworld；andyetyou’llfindfewamongthemoresensiblepeopleofthatcommunionwhodonotblametheGunpowder-treason，andthemassacreofSt。Bartholomew，ascruelandbarbarous，tho’projectedorexecutedagainstthoseverypeople，whomwithoutanyscrupletheycondemntoeternalandinfinitepunishments。Allwecansayinexcuseforthisinconsistencyis，thattheyreallydonotbelievewhattheyaffirmconcerningafuturestate；noristhereanybetterproofofitthantheveryinconsistency。
Wemayaddtothisaremark；thatinmattersofreligionmentakeapleasureinbeingterrify’d，andthatnopreachersaresopopular，asthosewhoexcitethemostdismalandgloomypassions。Inthecommonaffairsoflife，wherewefeelandarepenetratedwiththesolidityofthesubject，nothingcanbemoredisagreeablethanfearandterror；and’tisonlyindramaticperformancesandinreligiousdiscourses，thattheyevergivepleasure。Intheselattercasestheimaginationreposesitselfindolentlyontheidea；andthepassion，beingsoften’dbythewantofbeliefinthesubject，hasnomorethantheagreeableeffectofenliveningthemind，andfixingtheattention。
Thepresenthypothesiswillreceiveadditionalconfirmation，ifweexaminetheeffectsofotherkindsofcustom，aswellasofotherrelations。Tounderstandthiswemustconsider，thatcustom，towhichIattributeallbeliefandreasoning，mayoperateuponthemindininvigoratinganideaaftertwoseveralways。Forsupposingthatinallpastexperiencewehavefoundtwoobjectstohavebeenalwaysconjoin’dtogether，’tisevident，thatupontheappearanceofoneoftheseobjectsinanimpression，wemustfromcustommakeaneasytransitiontotheideaofthatobject，whichusuallyattendsit；andbymeansofthepresentimpressionandeasytransitionmustconceivethatideainastrongerandmorelivelymanner，thanwedoanyloosefloatingimageofthefancy。Butletusnextsuppose，thatamereideaalone，withoutanyofthiscuriousandalmostartificialpreparation，shou’dfrequentlymakeitsappearanceinthemind，thisideamustbydegreesacquireafacilityandforce；andbothbyitsfirmholdandeasyintroductiondistinguishitselffromanynewandunusualidea。Thisistheonlyparticular，inwhichthesetwokindsofcustomagree；andifitappear，thattheireffectsonthejudgment，aresimilarandproportionable，wemaycertainlyconclude，thattheforegoingexplicationofthatfacultyissatisfactory。Butcanwedoubtofthisagreementintheirinfluenceonthejudgment，whenweconsiderthenatureandeffectsOfEDUCATION？
Allthoseopinionsandnotionsofthings，towhichwehavebeenaccustomedfromourinfancy，takesuchdeeproot，that’tisimpossibleforus，byallthepowersofreasonandexperience，toeradicatethem；andthishabitnotonlyapproachesinitsinfluence，butevenonmanyoccasionsprevailsoverthatwhicha-risesfromtheconstantandinseparableunionofcausesandeffects。Herewemostnotbecontentedwithsaying，thatthevividnessoftheideaproducesthebelief:Wemustmaintainthattheyareindividuallythesame。Thefrequentrepetitionofanyideainfixesitintheimagination；butcou’dneverpossiblyofitselfproducebelief，ifthatactofthemindwas，bytheoriginalconstitutionofournatures，annex’donlytoareasoningandcomparisonofideas。Custommayleadusintosomefalsecomparisonofideas。Thisistheutmosteffectwecanconceiveofit。But’tiscertainitcou’dneversupplytheplaceofthatcomparison，norproduceanyactofthemind，whichnaturallybelong’dtothatprinciple。
Aperson，thathaslostalegoranarmbyamputation，endeavoursforalongtimeafterwardstoservehimselfwiththem。Afterthedeathofanyone，’tisacommonremarkofthewholefamily，butespeciallyoftheservants，thattheycanscarcebelievehimtobedead，butstillimaginehimtobeinhischamberorinanyotherplace，wheretheywereaccustomedtofindhim。Ihaveoftenheardinconversation，aftertalkingofaperson，thatisanywaycelebrated，thatone，whohasnoacquaintancewithhim，willsay，Ihaveneverseensuch-a-one，butalmostfancyIhave；sooftenhaveIheardtalkofhim。Alltheseareparallelinstances。
Ifweconsiderthisargumentfromeducationinaproperlight，’twillappearveryconvincing；andthemoreso，that’tisfoundedononeofthemostcommonphaenomena，thatisanywheretobemetwith。Iampersuaded，thatuponexaminationweshallfindmorethanonehalfofthoseopinions，thatprevailamongmankind，tobeowingtoeducation，andthattheprinciples，whicharethusimplicitelyembrac’d，overballancethose，whichareowingeithertoabstractreasoningorexperience。Asliars，bythefrequentrepetitionoftheirlies，comeatlasttorememberthem；sothejudgment，orrathertheimagination，bythelikemeans，mayhaveideassostronglyimprintedonit，andconceivetheminsofullalight，thattheymayoperateuponthemindinthesamemannerwiththose，whichthesenses，memoryorreasonpresenttous。Butaseducationisanartificialandnotanaturalcause，andasitsmaximsarefrequentlycontrarytoreason，andeventothemselvesindifferenttimesandplaces，itisneveruponthataccountrecogniz’dbyphilosophers；tho’inrealityitbebuiltalmostonthesamefoundationofcustomandrepetitionasourreasoningsfromcausesandeffects。(21)
OftheInfluenceofBelief。
Buttho’educationbedisclaim’dbyphilosophy，asafallaciousgroundofassenttoanyopinion，itprevailsneverthelessintheworld，andisthecausewhyallsystemsareapttoberejectedatfirstasnewandunusual。ThisperhapswillbethefateofwhatIhavehereadvanc’dconcerningbelief，andtho’theproofsIhaveproduc’dappeartomeperfectlyconclusive，Iexpectnottomakemanyproselytestomyopinion。Menwillscarceeverbepersuaded，thateffectsofsuchconsequencecanflowfromprinciples，whichareseeminglysoinconsiderable，andthatthefargreatestpartofourreasoningswithallouractionsandpassions，canbederiv’dfromnothingbutcustomandhabit。Toobviatethisobjection，Ishallhereanticipatealittlewhatwou’dmoreproperlyfallunderourconsiderationafterwards，whenwecometotreatofthepassionsandthesenseofbeauty。
Thereisimplantedinthehumanmindaperceptionofpainandpleasure，asthechiefspringandmovingprincipleofallitsactions。Butpainandpleasurehavetwowaysofmakingtheirappearanceinthemind；ofwhichtheonehaseffectsverydifferentfromtheother。Theymayeitherappearinimpressiontotheactualfeeling，oronlyinidea，asatpresentwhenImentionthem。’Tisevidenttheinfluenceoftheseuponouractionsisfarfrombeingequal。Impressionsalwaysactuatethesoul，andthatinthehighestdegree；but’tisnoteveryideawhichhasthesameeffect。Naturehasproceededwithcautioninthiscame，andseemstohavecarefullyavoidedtheinconveniencesoftwoextremes。Didimpressionsaloneinfluencethewill，weshouldeverymomentofourlivesbesubjecttothegreatestcalamities；because，tho’weforesawtheirapproach，weshouldnotbeprovidedbynaturewithanyprincipleofaction，whichmightimpelustoavoidthem。Ontheotherhand，dideveryideainfluenceouractions，ourconditionwouldnotbemuchmended。Forsuchistheunsteadinessandactivityofthought，thattheimagesofeverything，especiallyofgoodsandevils，arealwayswanderinginthemind；andwereitmov’dbyeveryidleconceptionofthiskind，itwouldneverenjoyamoment’speaceandtranquillity。
Naturehas，therefore，chosenamedium，andhasneitherbestow’doneveryideaofgoodandevilthepowerofactuatingthewill，noryethasentirelyexcludedthemfromthisinfluence。Tho’anidlefictionhasnoefficacy，yetwefindbyexperience，thattheideasofthoseobjects，whichwebelieveeitherareorwillbeexistent，produceinalesserdegreethesameeffectwiththoseimpressions，whichareimmediatelypresenttothesensesandperception。Theeffect，then，ofbeliefistoraiseupasimpleideatoanequalitywithourimpressions，andbestowonitalikeinfluenceonthepassions。Thiseffectitcanonlyhavebymakinganideaapproachanimpressioninforceandvivacity。Forasthedifferentdegreesofforcemakealltheoriginaldifferencebetwixtanimpressionandanidea，theymustofconsequencebethesourceofallthedifferencesintheeffectsoftheseperceptions，andtheirremoval，inwholeorinpart，thecauseofeverynewresemblancetheyacquire。Whereverwecanmakeanideaapproachtheimpressionsinforceandvivacity，itwilllikewiseimitatetheminitsinfluenceonthemind；andviceversa，whereitimitatestheminthatinfluence，asinthepresentcase，thismustproceedfromitsapproachingtheminforceandvivacity。Belief，therefore，sinceitcausesanideatoimitatetheeffectsoftheimpressions，mustmakeitresembletheminthesequalities，andisnothingbutamorevividandintenseconceptionofanyidea。This，then，maybothserveasanadditionalargumentforthepresentsystem，andmaygiveusanotionafterwhatmannerourreasoningsfromcausationareabletooperateonthewillandpassions。
Asbeliefisalmostabsolutelyrequisitetotheexcitingourpassions，sothepassionsintheirturnareveryfavourabletobelief；andnotonlysuchfactsasconveyagreeableemotions，butveryoftensuchasgivepain，douponthataccountbecomemorereadilytheobjectsoffaithandopinion。Acoward，whosefearsareeasilyawaken’d，readilyassentstoeveryaccountofdangerhemeetswith；asapersonofasorrowfulandmelancholydispositionisverycredulousofeverything，thatnourisheshisprevailingpassion。Whenanyaffectingobjectispresented，itgivesthealarm，andexcitesimmediatelyadegreeofitsproperpassion；especiallyinpersonswhoarenaturallyinclinedtothatpassion。Thisemotionpassesbyaneasytransitiontotheimagination；anddiffusingitselfoverourideaoftheaffectingobject，makesusformthatideawithgreaterforceandvivacity，andconsequentlyassenttoit，accordingtotheprecedentsystem。Admirationandsurprizehavethesameeffectastheotherpassions；andaccordinglywemayobserve，thatamongthevulgar，quacksandprojectorsmeetwithamoreeasyfaithuponaccountoftheirmagnificentpretensions，thaniftheykeptthemselveswithintheboundsofmoderation。Thefirstastonishment，whichnaturallyattendstheirmiraculousrelations，spreadsitselfoverthewholesoul，andsovivifiesandenlivenstheidea，thatitresemblestheinferenceswedrawfromexperience。Thisisamystery，withwhichwemaybealreadyalittleacquainted，andwhichweshallhavefartheroccasiontobeletintointheprogressofthistreatise。
Afterthisaccountoftheinfluenceofbeliefonthepassions，weshallfindlessdifficultyinexplainingitseffectsontheimagination，howeverextraordinarytheymayappear。’Tiscertainwecannottakepleasureinanydiscourse，whereourjudgmentgivesnoassenttothoseimageswhicharepresentedtoourfancy。Theconversationofthosewhohaveacquir’dahabitoflying，tho’inaffairsofnomoment，nevergivesanysatisfaction；andthatbecausethoseideastheypresenttous，notbeingattendedwithbelief，makenoimpressionuponthemind。Poetsthemselves，tho’liarsbyprofession，alwaysendeavourtogiveanairoftruthtotheirfictions；andwherethatistotallyneglected，theirperformances，howeveringenious，willneverbeabletoaffordmuchpleasure。Inshort，wemayobserve，thatevenwhenideashavenomannerofinfluenceonthewillandpassions，truthandrealityarestillrequisite，inordertomakethementertainingtotheimagination。
Butifwecomparetogetherallthephenomenathatoccuronthishead，weshallfind，thattruth，howevernecessaryitmayseeminallworksofgenius，hasnoothereffectthantoprocureaneasyreceptionfortheideas，andtomakethemindacquiesceinthemwithsatisfaction，oratleastwithoutreluctance。Butasthisisaneffect，whichmayeasilybesupposedtoflowfromthatsolidityandforce，which，accordingtomysystem，attendthoseideasthatareestablishedbyreasoningsfromcausation；itfollows，thatalltheinfluenceofbeliefuponthefancymaybeexplainedfromthatsystem。Accordinglywemayobserve，thatwhereverthatinfluencearisesfromanyotherprinciplesbesidetruthorreality，theysupplyitsplace，andgiveanequalentertainmenttotheimagination。Poetshaveform’dwhattheycallapoeticalsystemofthings，whichtho’itbebeliev’dneitherbythemselvesnorreaders，iscommonlyesteem’dasufficientfoundationforanyfiction。WehavebeensomuchaccustomedtothenamesofMARS，JUPITER，VENUS，thatinthesamemanneraseducationinfixesanyopinion，theconstantrepetitionoftheseideasmakesthementerintothemindwithfacility，andprevailuponthefancy，withoutinfluencingthejudgment。Inlikemannertragediansalwaysborrowtheirfable，oratleastthenamesoftheirprincipalactors，fromsomeknownpassageinhistory；andthatnotinordertodeceivethespectators；fortheywillfranklyconfess，thattruthisnotinanycircumstanceinviolablyobserved:butinordertoprocureamoreeasyreceptionintotheimaginationforthoseextraordinaryevents，whichtheyrepresent。Butthisisaprecaution，whichisnotrequiredofcomicpoets，whosepersonagesandincidents，beingofamorefamiliarkind，entereasilyintotheconception，andarereceivedwithoutanysuchformality，eventho’atfirstnighttheybeknowntobefictitious，andthepureoffspringofthefancy。
Thismixtureoftruthandfalshoodinthefablesoftragicpoetsnotonlyservesourpresentpurpose，byshewing，thattheimaginationcanbesatisfy’dwithoutanyabsolutebelieforassurance；butmayinanotherviewberegardedasaverystrongconfirmationofthissystem。’Tisevident，thatpoetsmakeuseofthisartificeofborrowingthenamesoftheirpersons，andthechiefeventsoftheirpoems，fromhistory，inordertoprocureamoreeasyreceptionforthewhole，andcauseittomakeadeeperimpressiononthefancyandaffections。Theseveralincidentsofthepieceacquireakindofrelationbybeingunitedintoonepoemorrepresentation；andifanyoftheseincidentsbeanobjectofbelief，itbestowsaforceandvivacityontheothers，whicharerelatedtoit。Thevividnessofthefirstconceptiondiffusesitselfalongtherelations，andisconvey’d，asbysomanypipesorcanals，toeveryideathathasanycommunicationwiththeprimaryone。This，indeed，canneveramounttoaperfectassurance；andthatbecausetheunionamongtheideasis，inamanner，accidental:Butstillitapproachessonear，initsinfluence，asmayconvinceus，thattheyarederiv’dfromthesameorigin。Beliefmustpleasetheimaginationbymeansoftheforceandvivacitywhichattendsit；sinceeveryidea，whichhasforceandvivacity，isfoundtobeagreeabletothatfaculty。
Toconfirmthiswemayobserve，thattheassistanceismutualbetwixtthejudgmentandfancy，aswellasbetwixtthejudgmentandpassion；andthatbeliefnotonlygivesvigourtotheimagination，butthatavigorousandstrongimaginationisofalltalentsthemostpropertoprocurebeliefandauthority。’Tisdifficultforustowithholdourassentfromwhatispaintedouttousinallthecoloursofeloquence；andthevivacityproduc’dbythefancyisinmanycasesgreaterthanthatwhicharisesfromcustomandexperience。Wearehurriedawaybythelivelyimaginationofourauthororcompanion；andevenbehimselfisoftenavictimtohisownfireandgenius。
Norwillitbeamisstoremark，thatasalivelyimaginationveryoftendegeneratesintomadnessorfolly，andbearsitagreatresemblanceinitsoperations；sotheyinfluencethejudgmentafterthesamemanner，andproducebelieffromtheverysameprinciples。Whentheimagination，fromanyextraordinaryfermentofthebloodandspirits，acquiressuchavivacityasdisordersallitspowersandfaculties，thereisnomeansofdistinguishingbetwixttruthandfalshood；buteveryloosefictionoridea，havingthesameinfluenceastheimpressionsofthememory，ortheconclusionsofthejudgment，isreceiv’donthesamefooting，andoperateswithequalforceonthepassions。Apresentimpressionandacustomarytransitionarenownolongernecessarytoenlivenourideas。Everychimeraofthebrainisasvividandintenseasanyofthoseinferences，whichweformerlydignify’dwiththenameofconclusionsconcerningmattersoffact，andsometimesasthepresentimpressionsofthesenses。
[Thefollowingthreeparagraphsareinsertedfromtheappendix。]
Wemayobservethesameeffectofpoetryinalesserdegree；andthisiscommonbothtopoetryandmadness，thatthevivacitytheybestowontheideasisnotderiv’dfromtheparticularsituationsorconnexionsoftheobjectsoftheseideas，butfromthepresenttemperanddispositionoftheperson。Buthowgreatsoeverthepitchmaybe，towhichthisvivacityrises，’tisevident，thatinpoetryitneverhasthesamefeelingwiththatwhicharisesinthemind，whenwereason，tho’evenuponthelowestspeciesofprobability。Themindcaneasilydistinguishbetwixttheoneandtheother；andwhateveremotionthepoeticalenthusiasmmaygivetothespirits，’tisstillthemerephantomofbelieforpersuasion。Thecaseisthesamewiththeidea，aswiththepassionitoccasions。Thereisnopassionofthehumanmindbutwhatmayarisefrompoetry；tho’atthesametimethefeelingsofthepassionsareverydifferentwhenexcitedbypoeticalfictions，fromwhattheyarewhentheyarefrombeliefandreality。Apassion，whichisdisagreeableinreallife，mayaffordthehighestentertainmentinatragedy，orepicpoem。Inthelattercase，itliesnotwiththatweightuponus:Itfeelslessfirmandsolid:Andhasnootherthantheagreeableeffectofexcitingthespirits，androuzingtheattention。Thedifferenceinthepassionsisaclearproofofalikedifferenceinthoseideas，fromwhichthepassionsarederiv’d。Wherethevivacityarisesfromacustomaryconjunctionwithapresentimpression；tho’theimaginationmaynot，inappearance，besomuchmov’d；yetthereisalwayssomethingmoreforcibleandrealinitsactions，thaninthefervorsofpoetryandeloquence。Theforceofourmentalactionsinthiscase，nomorethaninanyother，isnottobemeasur’dbytheapparentagitationofthemind。Apoeticaldescriptionmayhaveamoresensibleeffectonthefancy，thananhistoricalnarration。Itmaycollectmoreofthosecircumstances，thatformacompleatimageorpicture。Itmayseemtosettheobjectbeforeusinmorelivelycolours。Butstilltheideasitpresentsaredifferenttothefeelingfromthose，whicharisefromthememoryandthejudgment。Thereissomethingweakandimperfectamidstallthatseemingvehemenceofthoughtandsentiment，whichattendsthefictionsofpoetry。
Weshallafterwardshaveoccasiontoremarkboththeresemblanceanddifferencesbetwixtapoeticalenthusiasm，andaseriousconviction。InthemeantimeIcannotforbearobserving，thatthegreatdifferenceintheirfeelingproceedsinsomemeasurefromreflectionandgeneralrules。Weobserve，thatthevigourofconception，whichfictionsreceivefrompoetryandeloquence，isacircumstancemerelyaccidental，ofwhicheveryideaisequallysusceptible；andthatsuchfictionsareconnectedwithnothingthatisreal。Thisobservationmakesusonlylendourselves，sotospeak，tothefiction:Butcausestheideatofeelverydifferentfromtheeternalestablish’dpersuasionsfoundedonmemoryandcustom。Theyaresomewhatofthesamekind:Buttheoneismuchinferiortotheother，bothinitscausesandeffects。
Alikereflectionongeneralruleskeepsusfromaugmentingourbeliefuponeveryencreaseoftheforceandvivacityofourideas。Whereanopinionadmitsofnodoubt，oroppositeprobability，weattributetoitafullconviction:tho’thewantofresemblance，orcontiguity，mayrenderitsforceinferiortothatofotheropinions。’Tisthustheunderstandingcorrectstheappearancesofthesenses，andmakesusimagine，thatanobjectattwentyfootdistanceseemseventotheeyeaslargeasoneofthesamedimensionsatten。
Wemayobservethesameeffectofpoetryinalesserdegree；onlywiththisdifference，thattheleastreflectiondissipatestheillusionsofpoetry，andPlacestheobjectsintheirproperlight。’Tishowevercertain，thatinthewarmthofapoeticalenthusiasm，apoethasa，counterfeitbelief，andevenakindofvisionofhisobjects:Andiftherebeanyshadowofargumenttosupportthisbelief，nothingcontributesmoretohisfullconvictionthanablazeofpoeticalfiguresandimages，whichhavetheireffectuponthepoethimself，aswellasuponhisreaders。
OftheProbabilityofChances。
Butinordertobestowonthissystemitsfullforceandevidence，wemustcarryoureyefromitamomenttoconsideritsconsequences，andexplainfromthesameprinciplessomeotherspeciesofreasoning，whicharederiv’dfromthesameorigin。
Thosephilosophers，whohavedividedhumanreasonintoknowledgeandprobability，andhavedefin’dthefirsttobethatevidence，whicharisesfromthecomparisonofideas，areoblig’dtocomprehendallourargumentsfromcausesoreffectsunderthegeneraltermofprobability。Buttho’everyonebefreetousehistermsinwhatsensehepleases；andaccordinglyintheprecedentpartofthisdiscourse，Ihavefollow’dthismethodofexpression；’tishowevercertain，thatincommondiscoursewereadilyaffirm，thatmanyargumentsfromcausationexceedprobability，andmaybereceiv’dasasuperiorkindofevidence。’Onewou’dappearridiculous，whowou’dsay，that’tisonlyprobablethesunwillriseto-morrow，orthatallmenmustdye；tho’’tisplainwehavenofurtherassuranceofthesefacts，thanwhatexperienceaffordsus。Forthisreason，’twouldperhapsbemoreconvenient，inorderatoncetopreservethecommonsignificationofwords，andmarktheseveraldegreesofevidence，todistinguishhumanreasonintothreekinds，viz。thatfromknowledge，fromproofs，andfromprobabilities。Byknowledge，Imeantheassurancearisingfromthecomparisonofideas。Byproofs，thosearguments，whicharederiv’dfromtherelationofcauseandeffect，andwhichareentirelyfreefromdoubtanduncertainty。Byprobability，thatevidence，whichisstillattendedwithuncertainty。’Tisthislastspeciesofreasoning，Iproceedtoexamine。
Probabilityorreasoningfromconjecturemaybedividedintotwokinds，viz。thatwhichisfoundedonchance，andthatwhicharisesfromcauses。Weshallconsidereachoftheseinorder。
Theideaofcauseandeffectisderiv’dfromexperience，whichpresentinguswithcertainobjectsconstantlyconjoin’dwitheachother，producessuchahabitofsurveyingtheminthatrelation，thatwecannotwithoutasensibleviolencesurveythemiiianyother。Ontheotherhand，aschanceisnothingrealinitself，and，properlyspeaking，ismerelythenegationofacause，itsinfluenceonthemindiscontrarytothatofcausation；and’tisessentialtoit，toleavetheimaginationperfectlyindifferent，eithertoconsidertheexistenceornon-existenceofthatobject，whichisregardedascontingent。Acausetracesthewaytoourthought，andinamannerforcesustosurveysuchcertainobjects，insuchcertainrelations。Chancecanonlydestroythisdeterminationofthethought，andleavethemindinitsnativesituationofindifference；inwhich，upontheabsenceofacause，’tisinstantlyre-instated。
Sincethereforeanentireindifferenceisessentialtochance，noonechancecanpossiblybesuperiortoanother，otherwisethanasitiscompos’dofasuperiornumberofequalchances。Forifweaffirmthatonechancecan，afteranyothermanner，besuperiortoanother，wemustatthesametimeaffirm，thatthereissomething，whichgivesitthesuperiority，anddeterminestheeventrathertothatsidethantheother:Thatis，inotherwords，wemustallowofacause，anddestroythesuppositionofchance；whichwehadbeforeestablished。Aperfectandtotalindifferenceisessentialtochance，andonetotalindifferencecanneverinitselfbeeithersuperiororinferiortoanother。Thistruthisnotpeculiartomysystem，butisacknowledgedbyeveryone，thatformscalculationsconcerningchances。
Andhere’tisremarkable，thattho’chanceandcausationbedirectlycontrary，yet’tisimpossibleforustoconceivethiscombinationofchances，whichisrequisitetorenderonehazardsuperiortoanother，withoutsupposingamixtureofcausesamongthechances，andaconjunctionofnecessityinsomeparticulars，withatotalindifferenceinothers。Wherenothinglimitsthechances，everynotion，thatthemostextravagantfancycanform，isuponafootingofequality；norcantherebeanycircumstancetogiveonetheadvantageaboveanother。Thusunlessweallow，thattherearesomecausestomakethedicefall，andpreservetheirformintheirfall，andlieuponsomeoneoftheirsides，wecanformnocalculationconcerningthelawsofhazard。Butsupposingthesecausestooperate，andsupposinglikewisealltheresttobeindifferentandtobedeterminedbychance，’tiseasytoarriveatanotionofasuperiorcombinationofchances。Adyethathasfoursidesmark’dwithacertainnumberofspots，andonlytwowithanother，affordsusanobviousandeasyinstanceofthissuperiority。Themindisherelimitedbythecausestosuchaprecisenumberandqualityoftheevents；andatthesametimeisundeterminedinitschoiceofanyparticularevent。
Proceedingtheninthatreasoning，whereinwehaveadvanc’dthreesteps；thatchanceismerelythenegationofacause，andproducesatotalindifferenceinthemind；thatonenegationofacauseandonetotalindifferencecanneverbesuperiororinferiortoanother；andthattheremustalwaysbeamixtureofcausesamongthechances，inordertobethefoundationofanyreasoning:Wearenexttoconsiderwhateffectasuperiorcombinationofchancescanhaveuponthemind，andafterwhatmanneritinfluencesourjudgmentandopinion。Herewemayrepeatallthesameargumentsweemploy’dinexaminingthatbelief，whicharisesfromcauses；andmayprove，afterthesamemanner，thatasuperiornumberofchancesproducesourassentneitherbydemonstrationnorprobability。’Tisindeedevident’thatwecan’neverbythecomparisonofmereideasmakeanydiscovery，whichcanbeofconsequenceinthisaffairsandthat’tisimpossibletoprovewithcertainty，thatanyeventmustfallonthatsidewherethereisasuperiornumberofchances。To，supposeinthiscaseanycertainty，weretooverthrowwhatwehaveestablishedconcerningtheoppositionofchances，andtheirperfectequalityandindifference。
Shou’ditbesaid，thattho’inanoppositionofchances’tisimpossibletodeterminewithcertainty，onWhichsidetheeventwillfall，yetwecanpronouncewithcertainty，that’tismorelikelyandprobable，’twillbeonthatsidewherethereisasuperiornumberofchances，thanwherethereisaninferior:Shou’dthisbesaid，Iwou’dask，whatisheremeantbylikelihoodandprobability？Thelikelihoodandprobabilityofchancesisasuperiornumberofequalchances；andconsequentlywhenwesay’tislikelytheeventwinfallontheside，whichissuperior，ratherthanontheinferior，wedonomorethanaffirm，thatwherethereisasuperiornumberofchancesthereisactuallyasuperior，andwherethereisaninferiorthereisaninferior；whichareidenticalpropositions，andofnoconsequence。Thequestionis，bywhatmeansasuperiornumberofequalchancesoperatesuponthemind，andproducesbelieforassent；sinceitappears，that’tisneitherbyargumentsderiv’dfromdemonstration，norfromprobability。
Inordertoclearupthisdifficulty，weshallsupposeapersontotakeadye，form’daftersuchamannerasthatfourofitssidesaremark’dwithonefigure，oronenumberofspots，andtwowithanother；andtoputthisdyeintotheboxwithanintentionofthrowingit:’Tisplain，hemustconcludetheonefiguretobemoreprobablethantheother，andgivethepreferencetothatwhichisinscrib’donthegreatestnumberofsides。Heinamannerbelieves，thatthiswilllieuppermost；tho’stillwithhesitationanddoubt，inproportiontothenumberofchances，whicharecontrary:Andaccordingasthesecontrarychancesdiminish，andthesuperiorityencreasesontheotherside，hisbeliefacquiresnewdegreesofstabilityandassurance。Thisbeliefarisesfromanoperationoftheminduponthesimpleandlimitedobjectbeforeus；andthereforeitsnaturewillbethemoreeasilydiscoveredandexplain’d。Wehavenothingbutonesingledyetocontemplate，inordertocomprehendoneofthemostcuriousoperationsoftheunderstanding。
Thisdye，form’dasabove，containsthreecircumstancesworthyofourattention。First，Certaincauses，suchasgravity，solidity，acubicalfigure，&；c。whichdetermineittofall，topreserveitsforminitsfall，andtoturnuponeofitssides。Secondly，Acertainnumberofsides，whicharesuppos’dindifferent。Thirdly，Acertainfigureinscrib’doneachside。Thesethreeparticularsformthewholenatureofthedye，sofarasrelatestoourpresentpurpose；andconsequentlyaretheonlycircumstancesregardedbythemindinitsformingajudgmentconcerningtheresultofsuchathrow。Letus，therefore，considergraduallyandcarefullywhatmustbetheinfluenceofthesecircumstancesonthethoughtandimagination。
First，Wehavealreadyobserv’d，thatthemindisdetermin’dbycustomtopassfromanycausetoitseffect，andthatupontheappearanceoftheone，’tisalmostimpossibleforitnottoformanideaoftheother。Theirconstantconjunctioninpastinstanceshasproduc’dsuchahabitinthemind，thatitalwaysconjoinstheminitsthought，andinferstheexistenceoftheonefromthatofitsusualattendant。Whenitconsidersthedyeasnolongersupportedbythebox，itcannotwithoutviolenceregarditassuspendedintheair；butnaturallyplacesitonthetable，andviewsitasturninguponeofitssides。Thisistheeffectoftheintermingledcauses，whicharerequisitetoourforminganycalculationconcerningchances。
Secondly，’Tissuppos’d，thattho’thedyebenecessarilydetermin’dtofall，andturnuponeofitssides，yetthereisnothingtofixtheparticularside，butthatthisisdetermin’dentirelybychance。Theverynatureandessenceofchanceisanegationofcauses，andtheleavingthemindinaperfectindifferenceamongthoseevents，whicharesuppos’dcontingent。Whenthereforethethoughtisdeterminedbythecausestoconsiderthedyeasfallingandturninguponeofitssides，thechancespresentallthesesidesasequal，andmakeusconsidereveryoneofthem，oneafteranother，asalikeprobableandpossible。Theimaginationpassesfromthecause，viz。thethrowingofthedye，totheeffect，viz。theturninguponeofthesixsides；andfeelsakindofimpossibilitybothofstoppingshortintheway，andofforminganyotheridea。Butasallthesesixsidesareincompatible，andthedyecannotturnupaboveoneatonce，thisprincipledirectsusnottoconsiderallofthematonceaslyinguppermost；whichwelookuponasimpossible:Neitherdoesitdirectuswithitsentireforcetoanyparticularside；forinthatcasethissidewou’dbeconsideredascertainandinevitable；butitdirectsustothewholesixsidesaftersuchamannerastodivideitsforceequallyamongthem。Weconcludeingeneral，thatsomeoneofthemmustresultfromthethrow:Werunallofthemoverinourminds:Thedeterminationofthethoughtiscommontoall；butnomoreofitsforcefallstotheshareofanyone，thanwhatissuitabletoitsproportionwiththerest。’Tisafterthismannertheoriginalimpulse，andconsequentlythevivacityofthought，arisingfromthecauses，isdividedandsplitinpiecesbytheintermingledchances。
Wehavealreadyseentheinfluenceofthetwofirstqualitiesofthedye，viz。thecauses，andthenumberandindifferenceofthesides，andhavelearn’dhowtheygiveanimpulsetothethought，anddividethatimpulseintoasmanypartsasthereareunitesinthenumberofsides。Wemustnowconsidertheeffectsofthethirdparticular，viz。thefiguresinscrib’doneachside。’Tisevidentthatwhereseveralsideshavethesamefigureinscribeonthem，theymustconcurintheirinfluenceonthemind，andmustuniteupononeimageorideaofafigureallthosedividedimpulses，thatweredispers’dovertheseveralsides，uponwhichthatfigureisinscrib’d。Werethequestiononlywhatsidewillbeturn’dup，theseareallperfectlyequal，andnoonecou’deverhaveanyadvantageaboveanother。Butasthequestionisconcerningthefigure，andasthesamefigureispresentedbymorethanoneside:’tisevident，thattheimpulsesbelongingtoallthesesidesmustre-uniteinthatonefigure，andbecomestrongerandmoreforciblebytheunion。Foursidesaresuppos’dinthepresentcasetohavethesamefigureinscrib’donthem，andtwotohaveanotherfigure。Theimpulsesoftheformerare，therefore，superiortothoseofthelatter。Butastheeventsarecontrary，and’tisimpossibleboththesefigurescanbeturn’dup；theimpulseslikewisebecomecontrary，andtheinferiordestroysthesuperior，asfarasitsstrengthgoes。Thevivacityoftheideaisalwaysproportionabletothedegreesoftheimpulseortendencytothetransition；andbeliefisthesamewiththevivacityoftheidea，accordingtotheprecedentdoctrine。
OftheProbabilityofCauses。
WhatIhavesaidconcerningtheprobabilityofchancescanservetonootherpurpose，thantoassistusinexplainingtheprobabilityofcauses；since’tiscommonlyallow’dbyphilosophers，thatwhatthevulgarcallchanceisnothingbutasecretandconceal’dcause。Thatspeciesofprobability，therefore，iswhatwemustchieflyexamine。
Theprobabilitiesofcausesareofseveralkinds；butareallderiv’dfromthesameorigin，viz。theassociationofideastoapresentimpression。Asthehabit，whichproducestheassociation，arisesfromthefrequentconjunctionofobjects，itmustarriveatitsperfectionbydegrees，andmustacquirenewforcefromeachinstance，thatfallsunderourobservation。Thefirstinstancehaslittleornoforce:Thesecondmakessomeadditiontoit:Thethirdbecomesstillmoresensible；and’tisbytheseslowsteps，thatourjudgmentarrivesatafullassurance。Butbeforeitattainsthispitchofperfection，itpassesthro’severalinferiordegrees，andinallofthemisonlytobeesteem’dapresumptionorprobability。Thegradation，therefore，fromprobabilitiestoproofsisinmanycasesinsensible；andthedifferencebetwixtthesekindsofevidenceismoreeasilyperceiv’dintheremotedegrees，thaninthenearandcontiguous。
’Tisworthyofremarkonthisoccasion，thattho’thespeciesofprobabilityhereexplain’dbethefirstinorder，andnaturallytakesplacebeforeanyentireproofcanexist，yetnoone，whoisarriv’dattheageofmaturity，cananylongerbeacquaintedwithit。’Tistrue，nothingismorecommonthanforpeopleofthemostadvanc’dknowledgetohaveattain’donlyanimperfectexperienceofmanyparticularevents；whichnaturallyproducesonlyanimperfecthabitandtransition:Butthenwemustconsider，thatthemind，havingform’danotherobservationconcerningtheconnexionofcausesandeffects，givesnewforcetoitsreasoningfromthatobservation；andbymeansofitcanbuildanargumentononesingleexperiment，whendulyprepar’dandexamin’d。Whatwehavefoundoncetofollowfromanyobject，weconcludewillforeverfollowfromit；andifthismaximbenotalwaysbuiltuponascertain，’tisnotforwantofasufficientnumberofexperiments，butbecausewefrequentlymeetwithinstancestothecontrary；whichleadsustothesecondspeciesofprobability，wherethereisacontrarietyinourexperienceandobservation。
’Twou’dbeveryhappyformenintheconductoftheirlivesandactions，werethesameobjectsalwaysconjoin’dtogether，and，wehadnothingtofearbutthemistakesofourownjudgment，withouthavinganyreasontoapprehendtheuncertaintyofnature。Butas’tisfrequentlyfound，thatoneobservationiscontrarytoanother，andthatcausesandeffectsfollownotinthesameorder，ofwhichwehaveIhadexperience，weareoblig’dtovaryourreasoningon，accountofthisuncertainty，andtakeintoconsiderationthecontrarietyofevents。Thefirstquestion，thatoccursonthishead，isconcerningthenatureandcausesofthecontrariety。
Thevulgar，whotakethingsaccordingtotheirfirstappearance，attributetheuncertaintyofeventstosuchanuncertaintyinthecauses，asmakesthemoftenfailoftheirusualinfluence，tho’theymeetwithnoobstaclenorimpedimentintheiroperation。Butphilosophersobserving，thatalmostineverypartofnaturethereiscontain’davastvarietyofspringsandprinciples，whicharehid，byreasonoftheirminutenessorremoteness，findthat’tisatleastpossiblethecontrarietyofeventsmaynotproceedfromanycontingencyinthecause，butfromthesecretoperationofcontrarycauses。Thispossibilityisconvertedintocertaintybyfartherobservation，whentheyremark，thatuponanexactscrutiny，acontrarietyofeffectsalwaysbetraysacontrarietyofcauses，andproceedsfromtheirmutualhindranceandopposition。Apeasantcangivenobetterreasonforthestoppingofanyclockorwatchthantosay，thatcommonlyitdoesnotgoright:Butanartizaneasilyperceives，thatthesameforceinthespringorpendulumhasalwaysthesameinfluenceonthewheels；butfailsofitsusualeffect，perhapsbyreasonofagrainofdust，whichputsastoptothewholemovement。Fromtheobservationofseveralparallelinstances，philosophersformamaxim，thattheconnexionbetwixtallcausesandeffectsisequallynecessary，andthatitsseeminguncertaintyinsomeinstancesproceedsfromthesecretoppositionofcontrarycauses。
Buthoweverphilosophersandthevulgarmaydifferintheirexplicationofthecontrarietyofevents，theirinferencesfromitarealwaysofthesamekind，andfoundedonthesameprinciples。Acontrarietyofeventsinthepastmaygiveusakindofhesitatingbeliefforthefutureaftertwoseveralways。First，Byproducinganimperfecthabitandtransitionfromthepresentimpressiontotherelatedidea。Whentheconjunctionofanytwoobjectsisfrequent，withoutbeingentirelyconstant，themindisdeterminedtopassfromoneobjecttotheother；butnotwithsoentireahabit，aswhentheunionisuninterrupted，andalltheinstanceswehaveevermetwithareuniformandofapiece……Wefindfromcommonexperience，inouractionsaswellasreasonings，thataconstantperseveranceinanycourseoflifeproducesastronginclinationandtendencytocontinueforthefuture；tho’therearehabitsofinferiordegreesofforce，proportionedtotheinferiordegreesofsteadinessanduniformityinourconduct。
Thereisnodoubtbutthisprinciplesometimestakesplace，andproducesthoseinferenceswedrawfromcontraryphaenomena:tho’Iamperswaded，thatuponexaminationweshallnotfindittobetheprinciple，thatmostcommonlyinfluencesthemindinthisspeciesofreasoning。Whenwefollowonlythehabitualdeterminationofthemind，wemakethetransitionwithoutanyreflection，andinterposenotamoment’sdelaybetwixttheviewofoneobjectandthebeliefofthat，whichisoftenfoundtoattendit。Asthecustomdependsnotuponanydeliberation，itoperatesimmediately，withoutallowinganytimeforreflection。Butthismethodofproceedingwehavebutfewinstancesofinourprobablereasonings；andevenfewerthaninthose，whicharederiv’dfromtheuninterruptedconjunctionofobjects。Intheformerspeciesofreasoningwecommonlytakeknowinglyintoconsiderationthecontrarietyofpastevents；wecomparethedifferentsidesofthecontrariety，andcarefullyweightheexperiments，whichwehaveoneachside:Whencewemayconclude，thatourreasoningsofthiskindarisenotdirectlyfromthehabit，butinanobliquemanner；whichwemustnowendeavourtoexplain。
’Tisevident，thatwhenanobjectisattendedwithcontraryeffects，wejudgeofthemonlybyourpastexperience，andalwaysconsiderthoseaspossible，whichwehaveobserv’dtofollowfromit。Andaspastexperienceregulatesourjudgmentconcerningthepossibilityoftheseeffects，soitdoesthatconcerningtheirprobability；andthateffect，whichhasbeenthemostcommon，wealwaysesteemthemostlikely。Herethenaretwothingstobeconsidered，viz。thereasonswhichdetermineustomakethepastastandardforthefuture，andthemannerhowweextractasinglejudgmentfromacontrarietyofpastevents。
Firstwemayobserve，thatthesupposition，thatthefutureresemblesthepast，，isnotfoundedonargumentsofanykind，butisderiv’dentirelyfromhabit，bywhichwearedetermin’dtoexpectforthefuturethesametrainofobjects，towhichwehavebeenaccustom’d。Thishabitordeterminationtotransferthepasttothefutureisfullandperfect；andconsequentlythefirstimpulseoftheimaginationinthisspeciesofreasoningisendow’dwiththesamequalities。
But，secondly，wheninconsideringpastexperimentswefindthemofacontrarynature，thisdetermination，tho’fullandperfectinitself，presentsuswithnosteadyobject，butoffersusanumberofdisagreeingimagesinacertainorderandproportion。Thefirstimpulse，therefore，isherebrokeintopieces，anddiffusesitselfoverallthoseimages，ofwhicheachpartakesanequalshareofthatforceandvivacity，thatisderiv’dfromtheimpulse。Anyofthesepasteventsmayagainhappen；andwejudge，thatwhentheydohappen，theywillbemix’dinthesameproportionasinthepast。
Ifourintention，therefore，betoconsidertheproportionsofcontraryeventsinagreatnumberofinstances，theimagespresentedbyourpastexperiencemustremainintheir，andpreservetheirfirstproportions。Suppose，forinstance，Ihavefoundbylongobservation，thatoftwentyships，whichgotosea，onlynineteenreturn。SupposeIseeatpresenttwentyshipsthatleavetheport:Itransfermypastexperiencetothefuture，andrepresenttomyselfnineteenoftheseshipsasreturninginsafety，andoneasperishing。Concerningthistherecanbenodifficulty。Butaswefrequentlyrunoverthoseseveralideasofpastevents，inordertoformajudgmentconcerningonesingleevent，whichappearsuncertain；thisconsiderationmustchangethefirstformofourideas，anddrawtogetherthedividedimagespresentedbyexperience；since’tistoitwereferthedeterminationofthatparticularevent，uponwhichwereason。Manyoftheseimagesaresuppos’dtoconcur，andasuperiornumbertoconcurononeside。Theseagreeingimagesunitetogether，andrendertheideamorestrongandlively，notonlythanamerefictionoftheimagination，butalsothananyidea，whichissupportedbyalessernumberofexperiments。Eachnewexperimentisasanewstrokeofthepencil，whichbestowsanadditionalvivacityonthecolourswithouteithermultiplyingorenlargingthefigure。Thisoperationofthemindhasbeensofullyexplain’dintreatingoftheprobabilityofchance，thatIneednothereendeavourtorenderitmoreintelligible。Everypastexperimentmaybeconsider’dasakindofchance；Iitbeinguncertaintous，whethertheobjectwillexistconformabletooneexperimentoranother。Andforthisreasoneverythingthathasbeensaidontheonesubjectisapplicabletoboth。
Thusuponthewhole，contraryexperimentsproduceanimperfectbelief，eitherbyweakeningthehabit，orbydividingandafterwardsjoiningindifferentparts，thatperfecthabit，whichmakesusconcludeingeneral，thatinstances，ofwhichwehavenoexperience，mustnecessarilyresemblethoseofwhichwehave。
Tojustifystillfartherthisaccountofthesecondspeciesofprobability，wherewereasonwithknowledgeandreflectionfromacontrarietyofpastexperiments，Ishallproposethefollowingconsiderations，withoutfearingtogiveoffencebythatairofsubtilty，whichattendsthem。Justreasoningoughtstill，perhaps，toretainitsforce，howeversubtile；inthesamemannerasmatterpreservesitssolidityintheair，andfire，andanimalspirits，aswellasinthegrosserandmoresensibleforms。
First，Wemayobserve，thatthereisnoprobabilitysogreatasnottoallowofacontrarypossibility；becauseotherwise’twou’dceasetobeaprobability，andwou’dbecomeacertainty。Thatprobabilityofcauses，whichismostextensive，andwhichweatpresentexamine，dependsonacontrarietyofexperiments:and’tisevidentAnexperimentinthepastprovesatleastapossibilityforthefuture。
Secondly，Thecomponentpartsofthispossibilityandprobabilityareofthesamenature，anddifferinnumberonly，butnotinkind。Ithasbeenobserv’d，thatallsinglechancesareentirelyequal，andthattheonlycircumstance，whichcangiveanyevent，thatiscontingent，asuperiorityoveranotherisasuperiornumberofchances。Inlikemanner，astheuncertaintyofcausesisdiscoveryby-experience，whichpresentsuswithaviewofcontraryevents，’tisplain，thatwhenwetransferthepasttothefuture，theknowntotheunknown，everypastexperimenthasthesameweight，andthat’tisonlyasuperiornumberofthem，whichcanthrowtheballanceonanyside。Thepossibility，therefore，whichentersintoeveryreasoningofthiskind，iscompos’dofparts，whichareofthesamenaturebothamongthemselves，andwiththose，thatcomposetheoppositeprobability。
Thirdly，Wemayestablishitasacertainmaxim，thatinallmoralaswellasnaturalphaenomena，whereveranycauseconsistsofanumberofparts，andtheeffectencreasesordiminishes，accordingtothevariationofthatnumber，theeffectsproperlyspeaking，isacompoundedone，andarisesfromtheunionoftheseveraleffects，thatproceedfromeachpartofthecause。Thus，becausethegravityofabodyencreasesordiminishesbytheencreaseordiminutionofitsparts，weconcludethateachpartcontainsthisqualityandcontributestothegravityofthewhole。Theabsenceorpresenceofapartofthecauseisattendedwiththatofaproportionablepartoftheeffect。Thisconnexionorconstantconjunctionsufficientlyprovestheoneparttobethecauseoftheother。Asthebeliefwhichwehaveofanyevent，encreasesordiminishesaccordingtothenumberofchancesorpastexperiments，’tistobeconsideredasacompoundedeffect，ofwhicheachpartarisesfromaproportionablenumberofchancesorexperiments。
Letusnowjointhesethreeobservations，andseewhatconclusionwecandrawfromthem。Toeveryprobabilitythereisanoppositepossibility。Thispossibilityiscompos’dofparts，thatareentirelyofthesamenaturewiththoseoftheprobability；andconsequentlyhavethesameinfluenceonthemindandunderstanding。Thebelief，whichattendstheprobability，isacompoundedeffect，andisform’dbytheconcurrenceoftheseveraleffects，whichproceedfromeachpartoftheprobability。Sincethereforeeachpartoftheprobabilitycontributestotheproductionofthebelief，eachpartofthepossibilitymusthavethesameinfluenceontheoppositeside；thenatureofthesepartsbeingentirelythesame。Thecontrarybelief，attendingthepossibility，impliesaviewofacertainobject，aswellastheprobabilitydoesanoppositeview。Inthisparticularboththesedegreesofbeliefarealike。Theonlymannerthen，inwhichthesuperiornumberofsimilarcomponentpartsintheonecanexertitsinfluence，andprevailabovetheinferiorintheother，isbyproducingastrongerandmorelivelyviewofitsobject。Eachpartpresentsaparticularview；andalltheseviewsunitingtogetherproduceonegeneralview，whichisfullerandmoredistinctbythegreaternumberofcausesorprinciples，fromwhichitisderiv’d。
Thecomponentpartsoftheprobabilityandpossibility，beingalikeintheirnature，mustproducelikeeffects；andthelikenessoftheireffectsconsistsinthis，thateachofthempresentsaviewofaparticularobject。Buttho’thesepartsbealikeintheirnature，theyareverydifferentintheirquantityandnumber；andthisdifferencemustappearintheeffectaswellasthesimilarity。Nowastheviewtheypresentisinbothcasesfullandentire，andcomprehendstheobjectinallitsparts，’tisimpossiblethatinthisparticulartherecanbeanydifference；noristhereanythingbutasuperiorvivacityintheprobability，arisingfromtheconcurrenceofasuperiornumberofviews，whichcandistinguishtheseeffects。
Hereisalmostthesameargumentinadifferentlight。Allourreasoningsconcerningtheprobabilityofcausesarefoundedonthetransferringofpasttofuture。Thetransferringofanypastexperimenttothefutureissufficienttogiveusaviewoftheobject；whetherthatexperimentbesingleorcombin’dwithothersofthesamekind；whetheritbeentire，oroppos’dbyothersofacontrarykind。Suppose，then，itacquiresboththesequalitiesofcombinationandopposition，itlosesnotuponthataccountitsformerpowerofpresentingaviewoftheobject，butonlyconcurswithandopposesotherexperiments，thathavealikeinfluence。Aquestion，therefore，mayariseconcerningthemannerbothoftheconcurrenceandopposition。Astotheconcurrence，thereisonlythechoiceleftbetwixtthesetwohypotheses。First，Thattheviewoftheobject，occasionedbythetransferenceofeachpastexperiment，preservesitselfentire，andonlymultipliesthenumberofviews。Or，secondly，Thatitrunsintotheothersimilarandcorrespondentviews，andgivesthemasuperiordegreeofforceandvivacity。Butthatthefirsthypothesisiserroneous，isevidentfromexperience，whichinformsus，thatthebelief，attendinganyreasoning，consistsinoneconclusion，notinamultitudeofsimilarones，whichwou’donlydistractthemind，andinmanycaseswou’dbetoonumeroustobecomprehendeddistinctlybyanyfinitecapacity。Itremains，therefore，astheonlyreasonableopinion，thatthesesimilarviewsrunintoeachother，andunitetheirforces；soastoproduceastrongerandclearerview，thanwhatarisesfromanyonealone。Thisisthemanner，inwhichpastexperimentsconcur，whentheyaretransfer’dtoanyfutureevent。Astothemanneroftheiropposition，’tisevident，thatasthecontraryviewsareincompatiblewitheachother，and’tisimpossibletheobjectcanatonceexistconformabletobothofthem，theirinfluencebecomesmutuallydestructive，andthemindisdetermin’dtothesuperioronlywiththatforce，whichremains，aftersubtractingtheinferior。
Iamsensiblehowabstruseallthisreasoningmustappeartothegeneralityofreaders，whonotbeingaccustom’dtosuchprofoundreflectionsontheintellectualfacultiesofthemind，willbeapttorejectaschimericalwhateverstrikesnotinwiththecommonreceiv’dnotions，andwiththeeasiestandmostobviousprinciplesofphilosophy。Andnodoubttherearesomepainsrequir’dtoenterintothesearguments；tho’perhapsverylittlearenecessarytoperceivetheimperfectionofeveryvulgarhypothesisonthissubject，andthelittlelight，whichphilosophycanyetaffordusinsuchsublimeandsuchcuriousspeculations。Letmenbeoncefullyperswadedofthesetwoprinciples，Thatthere，isnothinginanyobject，consider’dinitself，whichcanaffordusareasonfordrawingaconclusionbeyondit；and，Thatevenaftertheobservationofthefrequentorconstantconjunctionofobjects，wehavenoreasontodrawanyinferenceconcerninganyobjectbeyondthoseofwhichwehavehadexperience；Isay，letmenbeoncefullyconvinc’dofthesetwoprinciples，andthiswillthrowthemsoloosefromallcommonsystems，thattheywillmakenodifficultyofreceivingany，whichmayappearthemostextraordinary。Theseprincipleswehavefoundtobesufficientlyconvincing，evenwithregardtoourmostcertainreasoningsfromcausation:ButIshallventuretoaffirm，thatwithregardtotheseconjecturalorprobablereasoningstheystillacquireanewdegreeofevidence。
First，’Tisobvious，thatinreasoningsofthiskind，’tisnottheobjectpresentedtous，which，consider’dinitself，affordsusanyreasontodrawaconclusionconcerninganyotherobjectorevent。Forasthislatterobjectissuppos’duncertain，andastheuncertaintyisderiv’dfromaconceal’dcontrarietyofcausesintheformer，wereanyofthecausesplac’dintheknownqualitiesofthatobject，theywou’dnolongerbeconceal’d，norwou’dourconclusionbeuncertain。
But，secondly，’tisequallyobviousinthisspeciesofreasoning，thatifthetransferenceofthepasttothefuturewerefoundedmerelyonaconclusionoftheunderstanding，itcou’dneveroccasionanybelieforassurance。Whenwetransfercontraryexperimentstothefuture，wecanonlyrepeatthesecontraryexperimentswiththeirparticularproportions；whichcou’dnotproduceassuranceinanysingleevent，uponwhichwereason，unlessthefancymeltedtogetherallthoseimagesthatconcur，andextractedfromthemonesingleideaorimage，whichisintenseandlivelyinproportiontothenumberofexperimentsfromwhichitisderiv’d，andtheirsuperiorityabovetheirantagonists。Ourpastexperiencepresentsnodeterminateobject；andasourbelief，howeverfaint，fixesitselfonadeterminateobject，’tisevidentthatthebeliefarisesnotmerelyfromthetransferenceofpasttofuture，butfromsomeoperationofthefancyconjoin’dwithit。Thismayleadustoconceivethemanner，inwhichthatfacultyentersintoallourreasonings。
Ishallconcludethissubjectwithtworeflections，whichmaydeserveourattention。Thefirstmaybeexplain’dafterthismanner。Whenthemindformsareasoningconcerninganymatteroffact，whichisonlyprobable，itcastsitseyebackwarduponpastexperience，andtransferringittothefuture，ispresentedwithsomanycontraryviewsofitsobject，ofwhichthosethatareofthesamekindunitingtogether，andrunningintooneactofthemind，servetofortifyandinlivenit。Butsupposethatthismultitudeofviewsorglimpsesofanobjectproceedsnotfromexperience，butfrom。avoluntaryactoftheimagination；thiseffectdoesnotfollow，oratleast，followsnotinthesamedegree。Fortho’customandeducationproducebeliefbysucharepetition，asisnotderiv’dfromexperience，yetthisrequiresalongtractoftime，alongwithaveryfrequentandundesign’drepetition。Ingeneralwemaypronounce，thatapersonwhowou’dvoluntarilyrepeatanyideainhismind，tho’supportedbyonepastexperience，wou’dbenomoreinclin’dtobelievetheexistenceofitsobject，thanifhehadcontentedhimselfwithonesurveyofit。Besidetheeffectofdesign；eachactofthemind，beingseparateandindependent，hasaseparateinfluence，andjoinsnotitsforcewiththatofitsfellows。Notbeingunitedbyanycommonobject，producingthem，theyhavenorelationtoeachother；andconsequentlymakenotransitionorunionofforces。Thisphaenomenonweshallunderstandbetterafterwards。
Mysecondreflectionisfoundedonthoselargeprobabilities，whichthemindcanjudgeof，andtheminutedifferencesitcanobservebetwixtthem。Whenthechancesorexperimentsononesideamounttotenthousand，andontheothertotenthousandandone，thejudgmentgivesthepreferencetothelatter，uponaccountofthatsuperiority；tho’’tisplainlyimpossibleforthemindtorunovereveryparticularview，anddistinguishthesuperiorvivacityoftheimagearisingfromthesuperiornumber，wherethedifferenceissoinconsiderable。Wehaveaparallelinstanceintheaffections。，’Tisevident，accordingtotheprinciplesabove-mention’d，thatwhenanobjectproducesanypassioninus，whichvariesaccordingtothedifferentquantityoftheobject；Isay，’tisevident，thatthepassion，properlyspeaking，isnotasimpleemotion，butacompoundedone，ofagreatnumberofweakerpassions，deriv’dfromaviewofeachpartoftheobject。Forotherwise’twereimpossiblethepassionshou’dencreasebytheencreaseoftheseparts。Thusaman，whodesiresathousandpound，hasinrealityathousandormoredesireswhichunitingtogether，seemtomakeonlyonepassion；tho’thecompositionevidentlybetraysitselfuponeveryalterationoftheobject，bythepreferencehegivestothelargernumber，ifsuperioronlybyanunite。Yetnothingcanbemorecertain，thanthatsosmalladifferencewou’dnotbediscernibleinthepassions，norcou’drenderthemdistinguishablefromeachother。Thedifference，therefore，ofourconductinpreferringthegreaternumberdependsnotuponourpassions，butuponcustom，andgeneralrules。Wehavefoundinamultitudeofinstances，thattheaugmentingthenumbersofanysumaugmentsthepassion，wherethenumbersarepreciseandthedifferencesensible。Themindcanperceivefromitsimmediatefeeling，thatthreeguineasproduceagreaterpassionthantwo；andthisittransferstolargernumbers，becauseoftheresemblance；andbyageneralruleassignstoathousandguineas，astrongerpassionthantoninehundredandninetynine。Thesegeneralrulesweshallexplainpresently。
Butbesidethesetwospeciesofprobability，whicha-rederiv’dfromanimperfectexperienceandfromcontrarycauses，thereisathirdarisingfromANALOGY，whichdiffersfromtheminsomematerialcircumstances。’Accordingtothehypothesisaboveexplain’dallkindsofreasoningfromcausesoreffectsarefoundedontwoparticulars，viz。，theconstantconjunctionofanytwoobjectsinallpastexperience，andtheresemblanceofapresentobjecttoanyoneofthem。Theeffectofthesetwoparticularsis，thatthepresentobjectinvigoratesandinlivenstheimagination；andtheresemblance，alongwiththeconstantunion，conveysthisforceandvivacitytotherelatedidea；whichwearethereforesaidtobelieve，orassentto。Ifyouweakeneithertheunionorresemblance，youweakentheprincipleoftransition，andofconsequencethatbelief，whicharisesfromit。Thevivacityofthefirstimpressioncannotbefullyconvey’dtotherelatedidea，eitherwheretheconjunctionoftheirobjectsisnotconstant，orwherethepresentimpressiondoesnotperfectlyresembleanyofthose，whoseunionweareaccustom’dtoobserve。Inthoseprobabilitiesofchanceandcausesabove-explain’d，’tistheconstancyoftheunion，whichisdiminish’d；andintheprobabilityderiv’dfromanalogy，’tistheresemblanceonly，whichisaffected。Withoutsomedegreeofresemblance，aswellasunion，’tisimpossibletherecanbeanyreasoning:butasthisresemblanceadmitsofmanydifferentdegrees，thereasoningbecomesproportionablymoreorlessfirmandcertain。Anexperimentlosesofitsforce，whentransferr’dtoinstances，whicharenotexactlyresembling；tho’’tisevidentitmaystillretainasmuchasmaybethefoundationofprobability，aslongasthereisanyresemblanceremaining。
