第2章

Butthisisquitecomprehensibleassoonasbothcountfornothingmorethanformalconditionsofoursensibility，whiletheobjectscountmerelyasphenomena;forthentheformofthephenomenon，i。e。，pureintuition，canbyallmeansberepresentedasproceedingfromourselves，thatis，apriori。Sect。12。Inordertoaddsomethingbywayofillustrationandconfirmation，weneedonlywatchtheordinaryandnecessaryprocedureofgeometers。Allproofsofthecompletecongruenceoftwogivenfigures（wheretheonecanineveryrespectbesubstitutedfortheother）comeultimatelytothisthattheymaybemadetocoincide;whichisevidentlynothingelsethanasyntheticalpropositionrestinguponimmediateintuition，andthisintuitionmustbepure，orgivenapriori，otherwisethepropositioncouldnotrankasapodicticallycertain，butwouldhaveempiricalcertaintyonly。 Inthatcase，itcouldonlybesaidthatitisalwaysfoundtobeso，andholdsgoodonlyasfarasourperceptionreaches。Thateverywherespace（which（initsentirety]isitselfnolongertheboundaryofanotherspace） hasthreedimensions，andthatspacecannotinanywayhavemore，isbasedonthepropositionthatnotmorethanthreelinescanintersectatrightanglesinonepoint;butthispropositioncannotbyanymeansbeshownfromconcepts，butrestsimmediatelyonintuition，andindeedonpureandaprioriintuition，becauseitisapodicticallycertain。Thatwecanrequirealinetobedrawntoinfinity（inindefinitum），orthataseriesofchanges（forexample，spacestraversedbymotion）shallbeinfinitelycontinued，presupposesarepresentationofspaceandtime，whichcanonlyattachtointuition，namely，sofarasitinitselfisboundedbynothing，forfromconceptsitcouldneverbeinferred。Consequently，thebasisofmathematicsactuallyarepureintuitions，whichmakeitssyntheticalandapodicticallyvalidpropositionspossible。Henceourtranscendentaldeductionofthenotionsofspaceandoftimeexplainsatthesametimethepossibilityofpuremathematics。Withoutsomesuchdeductionitstruthmaybegranted，butitsexistencecouldbynomeansbeunderstood，andwemustassumeII thateverythingwhichcanbegiventooursenses（totheexternalsensesinspace，totheinternaloneintime）isintuitdbyusasitappearstous，notasitisinitself。\"Sect。13。Thosewhocannotyetridthemselvesofthenotionthatspaceandtimeareactualqualitiesinheringinthingsinthemselves，mayexercisetheiracumenonthefollowingparadox。Whentheyhaveinvainattempteditssolution，andarefreefromprejudicesatleastforafewmoments，theywillsuspectthatthedegradationofspaceandoftimetomereformsof@ursensuousintuitionmayperhapsbewellfounded，Iftwothingsarequiteequalinallrespectsaskmuchascanbeascertainedbyallmeanspossible，quantitativelyandqualitatively，itmustfollow，thattheonecaninallcasesandunderallcircumstancesreplacetheother，andthissubstitutionwouldnotoccasiontheleastperceptibledifference。 Thisinfactistrueofplanefiguresingeometry;butsomesphericalfiguresexhibit，notwithstandingacompleteinternalagreement，suchacontrastintheirexternalrelation，thattheonefigurecannotpossiblybeputintheplaceoftheother。Forinstance，twosphericaltrianglesonoppositehemispheres，whichhaveanarcoftheequatorastheircommonbase，maybequiteequal，bothasregardssidesandangles，sothatnothingistobefoundineither，ifitbedescribedforitselfaloneandcompleted，thatwouldnotequallybeapplicabletoboth;andyettheonecannotbeputintheplaceoftheother（beingsituatedupontheoppositehemisphere）。 Herethenisaninternaldifferencebetweenthetwotriangles，whichdifferenceourunderstandingcannotdescribeasinternal，andwhichonlymanifestsitselfbyexternalrelationsinspace。ButIshalladduceexamples，takenfromcommonlife，thataremoreobviousstill。Whatcanbemoresimilarineveryrespectandineverypartmorealiketomyhandandtomyear，thantheirimagesinamirror？AndyetIcannotputsuchahandasisseenintheglassintheplaceofitsarchetype; forifthisisarighthand，thatintheglassisaleftone，andtheimageorreflectionoftherightearisaleftonewhichnevercanserveasasubstitutefortheother。Thereareinthiscasenointernaldifferenceswhichourunderstandingcoulddeterminebythinkingalone。Yetthedifferencesareinternalasthesensesteach，for，notwithstandingtheircompleteequalityandsimilarity，thelefthandcannotbeenclosedinthesameboundsastherightone（theyarenotcongruent）;thegloveofonehandcannotbeusedfortheother。Whatisthesolution？Theseobjectsarenotrepresentationsofthingsastheyareinthemselves，andasthepureunderstandingwouldknowthem，butsensuousintuitions，thatis，appearances，thepossibilityofwhichrestsupontherelationofcertainthingsunknowninthemselvestosomethingelse，viz。，tooursensibility。Spaceistheformoftheexternalintuitionofthissensibility，andtheinternaldeterminationofeveryspaceisonlypossiblebythedeterminationofitsexternalrelationtothewholespace，ofwhichitisapart（inotherwords，byitsrelationtotheexternalsense）。Thatistosay，thepartisonlypossiblethroughthewhole，whichisneverthecasewiththingsinthemselves，asobjectsofthemereunderstanding，butwithappearancesonly。Hencethedifferencebetweensimilarandequalthings，whichareyetnotcongruent（forinstance，twosymmetrichelices），cannotbemadeintelligiblebyanyconcept，butonlybytherelationtotherightandthelefthandswhichimmediatelyreferstointuition。REMARK1。PureMathematics，andespeciallypuregeometry，canonlyhaveobjectiverealityonconditionthattheyrefertoobjectsofsense。Butinregardtothelattertheprincipleholdsgood，thatoursenserepresentationisnotarepresentationofthingsinthemselvesbutofthewayinwhichtheyappeartous。Henceitfollows，thatthepropositionsofgeometryarenottheresultsofamerecreationofourpoeticimagination，andthatthereforetheycannotbereferredwithassurancetoactualobjects;butratherthattheyarenecessarilyvalidofspace，andconsequentlyofallthatmaybefoundinspace，becausespaceisnothingelsethantheformofallexternalappearances，anditisthisformaloneinwhichobjectsofsensecanbegiven。Sensibility，theformofwhichisthebasisofgeometry，isthatuponwhichthepossibilityofexternalappearancedepends。Thereforetheseappearancescannevercontainanythingbutwhatgeometryprescribestothem。Itwouldbequiteotherwiseifthesensesweresoconstitutedastorepresentobjectsastheyareinthemselves。Forthenitwouldnotbyanymeansfollowfromtheconceptionofspace，whichwithallitspropertiesservestothegeometerasanapriorifoundation，togetherwithwhatisthenceinferred，mustbesoinnature。Thespaceofthegeometerwouldbeconsideredamerefiction，anditwouldnotbecreditedwithobjectivevalidity，becausewecannotseehowthingsmustofnecessityagreewithanimageofthem，whichwemakespontaneouslyandprevioustoouracquaintancewiththem。 Butifthisimage，orratherthisformalintuition，istheessentialpropertyofoursensibility，bymeansofwhichaloneobjectsaregiventous，andifthissensibilityrepresentsnotthingsinthemselves，buttheirappearances： weshalleasilycomprehend，andatthesametimeindisputablyprove，thatallexternalobjectsofourworldofsensemustnecessarilycoincideinthemostrigorouswaywiththepropositionsofgeometry;becausesensibilitybymeansofitsformofexternalintuition，viz。，byspace，thesamewithwhichthegeometerisoccupied，makesthoseobjectsatallpossibleasmereappearances。Itwillalwaysremainaremarkablephenomenoninthehistoryofphilosophy，thattherewasatime，whenevenmathematicians，whoatthesametimewerephilosophers，begantodoubt，notoftheaccuracyoftheirgeometricalpropositionssofarastheyconcernedspace，butoftheirobjectivevalidityandtheapplicabilityofthisconceptitself，andofallitscorollaries，tonature。Theyshowedmuchconcernwhethera—lineinnaturemightnotconsistofphysicalpoints，andconsequentlythattruespaceintheobjectmightconsistofsimple[discrete]parts，whilethespacewhichthegeometerhasinhismind[beingcontinuous]cannotbesuch。Theydidnotrecognizethatthismentalspacerenderspossiblethephysicalspace，i。e。，theextensionofmatter;thatthispurespaceisnotatallaqualityofthingsinthemselves，butaformofoursensuousfacultyofrepresentation;andthatallobjectsinspacearemereappearances，i。e。，notthingsinthemselvesbutrepresentationsofoursensuousintuition。Butsuchisthecase，forthespaceofthegeometerisexactlytheformofsensuousintuitionwhichwefindaprioriinus，andcontainsthegroundofthepossibilityofallexternalappearances（accordingtotheirform），andthelattermustnecessarilyandmostrigidlyagreewiththepropositionsofthegeometer，whichhedrawsnotfromanyfictitiousconcept，butfromthesubjectivebasisofallexternalphenomena，whichissensibilityitself。InthisandnootherwaycangeometrybemadesecureastotheundoubtedobjectiverealityofitspropositionsagainstalltheintriguesofashallowMetaphysics，whichissurprisedatthem[thegeometricalpropositions]，becauseithasnottracedthemtothesourcesoftheirconcepts。REMARKII。Whateverisgivenusasobject，mustbegivenusinintuition。Allourintuitionhowevertakesplacebymeansofthesensesonly;theunderstandingintuitsnothing，butonlyreflects。Andaswehavejustshownthatthesensesneverandinnomannerenableustoknowthingsinthemselves，butonlytheirappearances，whicharemererepresentationsofthesensibility，weconcludethatallbodies，togetherwiththespaceinwhichtheyare，mustbeconsiderednothingbutmererepresentationsinus，andexistnowherebutinourthoughts。’Youwillsay：Isnotthismanifestidealism？Idealismconsistsintheassertion，thattherearenonebutthinkingbeings，allotherthings，whichwethinkareperceivedinintuition，beingnothingbutrepresentationsinthethinkingbeings，towhichnoobjectexternaltothemcorrespondsinfact。WhereasIsay，thatthingsasobjectsofoursensesexistingoutsideusaregiven，butweknownothingofwhattheymaybeinthemselves，knowingonlytheirappearances，1。e。，therepresentationswhichtheycauseinusbyaffectingoursenses。ConsequentlyIgrantbyallmeansthattherearebodieswithoutus，thatis，thingswhich，thoughquiteunknowntousastowhattheyareinthemselves，weyetknowbytherepresentationswhichtheirinfluenceonoursensibilityprocuresus，andwhichwecallbodies，atermsignifyingmerelytheappearanceofthethingwhichisunknowntous，butnotthereforelessactual。Canthisbetermedidealism？Itistheverycontrary。LongbeforeLocke’stime，butassuredlysincehim，ithasbeengenerallyassumedandgrantedwithoutdetrimenttotheactualexistenceofexternalthings，thatmanyoftheirpredicatesmaybesaidtobelongnottothethingsinthemselves，buttotheirappearances，andtohavenoproperexistenceoutsideourrepresentation。Heat，color，andtaste，forinstance，areofthiskind。Now，ifIgofarther，andforweightyreasonsrankasmereappearancestheremainingqualitiesofbodiesalso，whicharecalledprimary，suchasextension，place，andingeneralspace，withallthatwhichbelongstoit（impenetrabilityormateriality，space，etc。）—nooneintheleastcanadducethereasonofitsbeinginadmissible。Aslittleasthemanwhoadmitscolorsnottobepropertiesoftheobjectinitself，butonlyasmodificationsofthesenseofsight，shouldonthataccountbecalledanidealist，solittlecanmysystembenamedidealistic，merelybecauseI findthatmore，nay，A11thepropertieswhichconstitutetheintuitionofabodybelongmerelytoitsappearance。Theexistenceofthethingthatappearsistherebynotdestroyed，asingenuineidealism，butitisonlyshown，thatwecannotpossiblyknowitbythesensesasitisinitself。Ishouldbegladtoknowwhatmyassertionsmustbeinordertoavoidallidealism。Undoubtedly，Ishouldsay，thattherepresentationofspaceisnotonlyperfectlyconformabletotherelationwhichoursensibilityhastoobjects—thatIhavesaid—butthatitisquitesimilartotheobject，—anassertioninwhichIcanfindaslittlemeaningasifIsaidthatthesensationofredhasasimilaritytothepropertyofvermilion，whichinmeexcitesthissensation。REMARKIII。Hencewemayatoncedismissaneasilyforeseenbutfutileobjection，\"thatbyadmittingtheidealityofspaceandoftimethewholesensibleworldwouldbeturnedintomeresham。\"Atfirstallphilosophicalinsightintothenatureofsensuouscognitionwasspoiled，bymakingthesensibilitymerelyaconfusedmodeofrepresentation，accordingtowhichwestillknowthingsastheyare，butwithoutbeingabletoreduceeverythinginthisourrepresentationtoaclearconsciousness;whereasproofisofferedbyusthatsensibilityconsists，notinthislogicaldistinctionofclearnessandobscurity，butinthegeneticaloneoftheoriginofcognitionitself。 Forsensuousperceptionrepresentsthingsnotatallastheyare，butonlythemodeinwhichtheyaffectoursenses，andconsequentlybysensuousperceptionappearancesonlyandnotthingsthemselvesaregiventotheunderstandingforreflection。Afterthisnecessarycorrective，anobjectionrisesfromanunpardonableandalmostintentionalmisconception，asifmydoctrineturnedallthethingsoftheworldofsenseintomereillusion。Whenanappearanceisgivenus，wearestillquitefreeastohowweshouldjudgethematter。Theappearancedependsuponthesenses，butthejudgmentupontheunderstanding，andtheonlyquestionis，whetherinthedeterminationoftheobjectthereistruthornot。Butthedifferencebetweentruthanddreamingisnotascertainedbythenatureoftherepresentations，whicharereferredtoobjects（fortheyarethesameinbothcases），butbytheirconnectionaccordingtothoserules，whichdeterminethecoherenceoftherepresentationsintheconceptofanobject，andbyascertainingwhethertheycansubsisttogetherinexperienceornot。Anditisnotthefaultoftheappearancesifourcognitiontakesillusionfortruth，i。e。，iftheintuition，bywhichanobjectisgivenus，isconsideredaconceptofthethingorofitsexistencealso，whichtheunderstandingcanonlythink。Thesensesrepresenttousthepathsoftheplanetsasnowprogressive，nowretrogressive，andhereinisneitherfalsehoodnortruth，becauseaslongasweholdthispathtobenothingbutappearance，wedonotjudgeoftheobjectivenatureoftheirmotion。Butasafalsejudgmentmayeasilyarisewhentheunderstandingisnotonitsguardagainstthissubjectivemodeofrepresentationbeingconsideredobjective，wesaytheyappeartomovebackward;itisnotthesenseshoweverwhichmustbechargedwiththeillusion，buttheunderstanding，whoseprovincealoneitistogiveanobjectivejudgmentonappearances。Thus，evenifwedidnotatallreflectontheoriginofourrepresentations，wheneverweconnectourintuitionsofsense（whatevertheymaycontain），inspaceandintime，accordingtotherulesofthecoherenceofallcognitioninexperience，illusionortruthwillariseaccordingaswearenegligentorcareful。Itismerelyaquestionoftheuseofsensuousrepresentationsintheunderstanding，andnotoftheirorigin。Inthesameway，ifIconsideralltherepresentationsofthesenses，togetherwiththeirform，spaceandtime，tobenothingbutappearances，andspaceandtimetobeamereformofthesensibility，whichisnottobemetwithinobjectsoutofit，andifImakeuseoftheserepresentationsinreferencetopossibleexperienceonly，thereisnothinginmyregardingthemasappearancesthatcanleadastrayorcauseillusion。Forallthattheycancorrectlycohereaccordingtorulesoftruthinexperience。Thusallthepropositionsofgeometryholdgoodofspaceaswellasofalltheobjectsofthesenses，consequentlyofallpossibleexperience，whetherIconsiderspaceasamereformofthesensibility，orassomethingcleavingtothethingsthemselves。 IntheformercasehoweverIcomprehendhowIcanknowapriorithesepropositionsconcerningalltheobjectsofexternalintuition。Otherwise，everythingelseasregardsallpossibleexperienceremainsjustasifI hadnotdepartedfromthevulgarview。ButifIventuretogobeyondallpossibleexperiencewithmynotionsofspaceandtime，whichIcannotrefrainfromdoingifIproclaimthemqualitiesinherentinthingsinthemselves（forwhatshouldpreventmefromlettingthemholdgoodofthesamethings，eventhoughmysensesmightbedifferent，andunsuitedtothem？），thenagraveerrormayariseduetoillusion，forthusIwouldproclaimtobeuniversallyvalidwhatismerelyasubjectiveconditionoftheintuitionofthingsandsureonlyforallobjectsofsense，viz。，forallpossibleexperience;Iwouldreferthisconditiontothingsinthemselves，anddonotlimitittotheconditionsofexperience。Mydoctrineoftheidealityofspaceandoftime，therefore，farfromreducingthewholesensibleworldtomereillusion，istheonlymeansofsecuringtheapplicationofoneofthemostimportantcognitions（thatwhichmathematicspropoundsapriori）toactualobjects，andofpreventingitsbeingregardedasmereillusion。Forwithoutthisobservationitwouldbequiteimpossibletomakeoutwhethertheintuitionsofspaceandtime，whichweborrowfromnoexperience，andwhichyetlieinourrepresentationapriori，arenotmerephantasmsofourbrain，towhichobjectsdonotcorrespond，atleastnotadequately，andconsequently，whetherwehavebeenabletoshowitsunquestionablevaliditywithregardtoalltheobjectsofthesensibleworldjustbecausetheyaremereappearances。Secondly，thoughthesemyprinciplesmakeappearancesoftherepresentationsofthesenses，theyaresofarfromturningthetruthofexperienceintomereillusion，thattheyarerathertheonlymeansofpreventingthetranscendentalillusion，bywhichmetaphysicshashithertobeendeceived，leadingtothechildishendeavorofcatchingatbubbles，becauseappearances，whicharemererepresentations，weretakenforthingsinthemselves。HereoriginatedtheremarkableeventoftheantimonyofReasonwhichIshallmentionbyandby，andwhichisdestroyedbythesingleobservation，thatappearance，aslongasitisemployedinexperience，producestruth，butthemomentittransgressestheboundsofexperience，andconsequentlybecomestranscendent，producesnothingbutillusion。Inasmuchtherefore，asIleavetothingsasweobtainthembythesensestheiractuality，andonlylimitoursensuousintuitionofthesethingstothis，thattheyrepresentinnorespect，noteveninthepureintuitionsofspaceandoftime，anythingmorethanmereappearanceofthosethin—s，butnevertheirconstitutioninthemselves，thisisnotasweepingillusioninventedfornaturebyme。Myprotestationtooagainstallchargesofidealismissovalidandclearaseventoseemsuperfluous，weretherenotincompetentjudges，who，whiletheywouldhaveanoldnameforeverydeviationfromtheirperversethoughcommonopinion，andneverjudgeofthespiritofphilosophicnomenclature，butclingtotheletteronly，arereadytoputtheirownconceitsintheplaceofwell—definednotions，andtherebydeformanddistortthem。Ihavemyselfgiventhismytheorythenameoftranscendentalidealism，butthatcannotauthorizeanyonetoconfounditeitherwiththeempiricalidealismofDescartes，（indeed，hiswasonlyaninsolubleproblem，owingtowhichhethoughteveryoneatlibertytodenytheexistenceofthecorporealworld，becauseitcouldneverbeprovedsatisfactorily），orwiththemysticalandvisionaryidealismofBerkeley，againstwhichandothersimilarphantasmsourCritiquecontainstheproperantidote。 Myidealismconcernsnottheexistenceofthings（thedoubtingofwhich，however，constitutesidealismintheordinarysense），sinceitnevercameintomyheadtodoubtit，butitconcernsthesensuousrepresentationofthings，towhichspaceandtimeespeciallybelong。Ofthese[viz。，spaceandtime]，consequentlyofallappearancesingeneral，Ihaveonlyshown，thattheyareneitherthings（butmeremodesofrepresentation），nordeterminationsbelongingtothingsinthemselves。Buttheword\"transcendental，\"whichwithmemeansareferenceofourcognition，i。e。，nottothings，butonlytothecognitivefaculty，wasmeanttoobviatethismisconception。Yetratherthangivefurtheroccasiontoitbythisword，Inowretractit，anddesirethisidealismofminetobecalledcritical。Butifitbereallyanobjectionableidealismtoconvertactualthin。—Is（notappearances） intomererepresentations……bywhatnameshallwecallhimwhoconverselychangesmererepresentationstothings？Itmay，Ithink，becalled\"dreamingidealism，\"incontradistinctiontotheformer，whichmaybecalled\"visionary，\" bothofwhicharetoberefutedbymytranscendental，or，better，criticalidealism。Kant’s\"Prolegomena\"—SecondPart（InternetEncyclopediaofPhilosophy）SecondPartOfTheTranscendentalProblem：HowIsTheScienceOfNaturePossible？Sect。14。Natureistheexistenceofthings，sofarasitisdeterminedaccordingtouniversallaws。Shouldnaturesignifytheexistenceofthingsinthemselves，wecouldneverknowiteitherapriorioraposteriori。 Notapriori，forhowcanweknowwhatbelongstothingsinthemselves，sincethisnevercanbedonebythedissectionofourconcepts（inanalyticaljudgments）？Wedonotwanttoknowwhatiscontainedinourconceptofathing（forthe[conceptdescribeswhat]belongstoitslogicalbeing），butwhatisintheactualityofthethingsuperaddedtoourconcept，andbywhatthethingitselfisdeterminedinitsexistenceoutsidetheconcept。 Ourunderstanding，andtheconditionsonwhichaloneitcanconnectthedeterminationsofthingsintheirexistence，donotprescribeanyruletothingsthemselves;thesedonotconformtoourunderstanding，butitmustconformitselftothem;theymustthereforebefirstgivenusinordertogatherthesedeterminationsfromthem，whereforetheywouldnotbeknownapriori。Acognitionofthenatureofthingsinthemselvesaposterioriwouldbeequallyimpossible。For，ifexperienceistoteachuslaws，towhichtheexistenceofthingsissubject，theselaws，iftheyregardthingsinthemselves，mustbelongtothemofnecessityevenoutsideourexperience。 Butexperienceteachesuswhatexistsandhowitexists，butneverthatitmustnecessarilyexistsoandnototherwise。Experiencethereforecanneverteachusthenatureofthingsinthemselves。Sect。15。Weneverthelessactuallypossessapurescienceofnatureinwhicharepropounded，aprioriandwithallthenecessityrequisitetoapodicticalpropositions，lawstowhichnatureissubject。Ineedonlycalltowitnessthatpropaedeuticofnaturalsciencewhich，underthetitleoftheuniversalScienceofNature，precedesallPhysics（whichisfoundeduponempiricalprinciples）。InitwehaveMathematicsappliedtoappearance，andalsomerelydiscursiveprinciples（orthosederivedfromconcepts），whichconstitutethephilosophicalpartofthepurecognitionofnature。 Butthereareseveralthingsinit，whicharenotquitepureandindependentofempiricalsources：suchastheconceptofmotion，thatofimpenetrability（uponwhichtheempiricalconceptofmatterrests），thatofinertia，andmanyothers，whichpreventitsbeingcalledaperfectlypurescienceofnature。Besides，itonlyreferstoobjectsoftheexternalsenseandthereforedoesnotgiveanexampleofauniversalscienceofnature，inthestrictsense，forsuchasciencemustreducenatureingeneral，whetheritregardstheobjectoftheexternalorthatoftheinternalsense（theobjectofPhysicsaswellasPsychology），touniversallaws。Butamongtheprinciplesofthisuniversalphysicsthereareafewwhichactuallyhavetherequireduniversality;forinstance，thepropositionsthat\"substanceispermanent，\"andthat\"everyeventisdeterminedbyacauseaccordingtoconstantlaws，\"etc。Theseareactuallyuniversallawsofnature，whichsubsistcompletelyapriori。Thereistheninfactapurescienceofnature，andthequestionarises，Howisitpossible？Sect。16。Theword\"nature\"assumesyetanothermeaning，whichdeterminestheobject，whereasintheformersenseitonlydenotestheconformitytolaw[Gesetzmdssigkeit]ofthedeterminationsoftheexistenceofthingsgenerally。Ifweconsideritmaterialiter（i。e。，inthematterthatformsitsobjects）\"natureisthecomplexofalltheobjectsofexperience。\" Andwiththisonlyarewenowconcerned，forbesides，thingswhichcanneverbeobjectsofexperience，iftheymustbeknownastotheirnature，wouldobligeustohaverecoursetoconceptswhosemeaningcouldneverbegiveninconcrete（byanyexampleofpossibleexperience）。Consequentlywemustformforourselvesalistofconceptsoftheirnature，therealitywhereof（i。e。，whethertheyactuallyrefertoobjects，oraremerecreationsofthought）couldneverbedetermined。Thecognitionofwhatcannotbeanobjectofexperiencewouldbehyperphysical，andwiththingshyperphysicalweareherenotconcerned，butonlywiththecognitionofnature，theactualityofwhichcanbeconfirmedbyexperience，thoughit[thecognitionofnature] ispossibleaprioriandprecedesallexperience。Sect。17。Theformal[aspect]ofnatureinthisnarrowersenseisthereforetheconformitytolawofalltheobjectsofexperience，andsofarasitisknownapriori，theirnecessaryconformity。Butithasjustbeenshownthatthelawsofnaturecanneverbeknownaprioriinobjectssofarastheyareconsiderednotinreferencetopossibleexperience，butasthingsinthemselves。Andourinquiryhereextendsnottothingsinthemselves（thepropertiesofwhichwepassby），buttothingsasobjectsofpossibleexperience，andthecomplexoftheseiswhatweproperlydesignateasnature。AndnowIask，whenthepossibilityofacognitionofnatureaprioriisinquestion，whetheritisbettertoarrangetheproblemthus：Howcanweknowapriorithatthingsasobjectsofexperiencenecessarilyconformtolaw？orthus：Howisitpossibletoknowapriorithenecessaryconformitytolawofexperienceitselfasregardsallitsobjectsgenerally？Closelyconsidered，thesolutionoftheproblem，representedineitherway，amounts，withregardtothepurecognitionofnature（whichisthepointofthequestionatissue），entirelytothesamething。Forthesubjectivelaws，underwhichaloneanempiricalcognitionofthingsispossible，holdgoodofthesethings，asobjectsofpossibleexperience（notasthingsinthemselves，whicharenotconsideredhere）。Eitherofthefollowingstatementsmeansquitethesame：\"Ajudgmentofobservationcanneverrankasexperience，withoutthelaw，that’wheneveraneventisobserved，itisalwaysreferredtosomeantecedent，whichitfollowsaccordingtoauniversalrule’\";alternatively，\"Everything，ofwhichexperienceteachesthatithappens，musthaveacause。\"Itis，however，morecommendabletochoosethefirstformula。Forwecanaprioriandprevioustoallgivenobjectshaveacognitionofthoseconditions，onwhichaloneexperienceispossible，butneverofthelawstowhichthingsmayinthemselvesbesubject，withoutreferencetopossibleexperience。Wecannotthereforestudythenatureofthingsaprioriotherwisethanbyinvestigatingtheconditionsandtheuniversal（thoughsubjective）laws，underwhichalonesuchacognitionasexperience（astomereform）ispossible，andwedetermineaccordinglythepossibilityofthings，asobjectsofexperience。ForifIshouldchoosethesecondformula，andseektheconditionsapriori，onwhichnatureasanobjectofexperienceispossible，Imighteasilyfallintoerror，andfancythatIwasspeakingofnatureasathinginitself，andthenmoveroundinendlesscircles，inavainsearchforlawsconcerningthingsofwhichnothingisgivenme。Accordinglyweshallherebeconcernedwithexperienceonly，andtheuniversalconditionsofitspossibilitywhicharegivenapriori。Thenceweshalldeterminenatureasthewholeobjectofallpossibleexperience。 IthinkitwillbeunderstoodthatIheredonotmeantherulesoftheobservationofanaturethatisalreadygiven，forthesealreadypresupposeexperience。Idonotmeanhow（throughexperience）wecanstudythelawsofnature;forthesewouldnotthenbelawsapriori，andwouldyieldusnopurescienceofnature;but[Imeantoask]howthecondi。 tionsaprioriofthepossibilityofexperienceareatthesametimethesourcesfromwhichalltheuniversallawsofnaturemustbederived。Sect。18。Inthefirstplacewemuststatethat，whilealljudgmentsofexperience[Erfahrungsurtheile]areempirical（i。e。，havetheirgroundinimmediatesenseperception），viceversa，allempiricaljudgments[empirischeUrtheile]arenotjudgmentsofexperience，but，besidestheempirical，andingeneralbesideswhatisgiventothesensuousintuition，particularconceptsmustyetbesuperadded—conceptswhichhavetheiroriginquiteaprioriinthepureunderstanding，andunderwhicheveryperceptionmustbefirstofallsubsumedandthenbytheirmeanschangedintoexperience。8Empiricaljudgments，sofarastheyhaveobjectivevalidity，arejudgmentsofexperience;butthosewhichareonlysubjectivelyvalid，Inamemerejudgmentsofperception。Thelatterrequirenopureconceptoftheunderstanding，butonlythelogicalconnectionofperceptioninathinkingsubject。Buttheformeralwaysrequire，besidestherepresentationofthesensuousintuition，particularconceptsoriginallybegottenintheunderstanding，whichproducetheobjectivevalidityofthejudgmentofexperience。Allourjudgmentsareatfirstmerelyjudgmentsofperception;theyholdgoodonlyforus（i。e。，foroursubject），andwedonottillafterwardsgivethemanewreference（toanobject），anddesirethattheyshallalwaysholdgoodforusandinthesamewayforeverybodyelse;forwhenajudgmentagreeswithanobject，alljudgmentsconcerningthesameobjectmustlikewiseagreeamongthemselves，andthustheobjectivevalidityofthejudgmentofexperiencesignifiesnothingelsethanitsnecessaryuniversalityofapplication。Andconverselywhenwehavereasontoconsiderajudgmentnecessarilyuniversal（whichneverdependsuponperception，butuponthepureconceptoftheunderstanding，underwhichtheperceptionissubsumed），wemustconsideritobjectivealso，thatis，thatitexpressesnotmerelyareferenceofourperceptiontoasubject，butaqualityoftheobject。 Fortherewouldbenoreasonforthejudgmentsofothermennecessarilyagreeingwithmine，ifitwerenottheunityoftheobjecttowhichtheyallrefer，andwithwhichtheyaccord;hencetheymustallagreewithoneanother。Sect。19。Thereforeobjectivevalidityandnecessaryuniversality（foreverybody）areequivalentterms，andthoughwedonotknowtheobjectinitself，yetwhenweconsiderajudgmentasuniversal，andalsonecessary，weunderstandittohaveobjectivevalidity。Bythisjudgmentweknowtheobject（thoughitremainsunknownasitisinitself）bytheuniversalandnecessaryconnectionofthegivenperceptions。Asthisisthecasewithallobjectsofsense，judgmentsofexperiencetaketheirobjectivevaliditynotfromtheimmediatecognitionoftheobject（whichisimpossible），butfromtheconditionofuniversalvalidityinempiricaljudgments，which，asalreadysaid，neverrestsuponempirical，or，inshort，sensuousconditions，butuponapureconceptoftheunderstanding。Theobjectalwaysremainsunknowninitself;butwhenbytheconceptoftheunderstandingtheconnectionoftherepresentationsoftheobject，whicharegiventooursensibility，isdeterminedasuniversallyvalid，theobjectisdeterminedbythisrelation，anditisthejudgmentthatisobjective。Toillustratethematter：Whenwesay，\"theroomiswarm，sugarsweet，andwormwoodbitter，\"9——wehaveonlysubjectivelyvalidjudgments，IdonotatallexpectthatIoranyotherpersonshallalwaysfinditasInowdo;eachofthesesentencesonlyexpressesarelationoftwosensationstothesamesubject，tomyself，andthatonlyinmypresentstateofperception; consequentlytheyarenotvalidoftheobject。Sucharejudgmentsofperception。 judgmentsofexperienceareofquiteadifferentnature。Whatexperienceteachesmeundercertaincircumstances，itmustalwaysteachmeandeverybody; anditsvalidityisnotlimitedtothesubjectnortoitsstateataparticulartime。HenceIpronounceallsuchjudgmentsasbeingobjectivelyvalid。 Forinstance，whenIsaytheairiselastic，thisjudgmentisasyetajudgmentofperceptiononly—Idonothingbutrefertwoofmysensationstooneanother。But，ifIwouldhaveitcalledajudgmentofexperience，Irequirethisconnectiontostandunderacondition，whichmakesituniversallyvalid。IdesirethereforethatIandeverybodyelseshouldalwaysconnectnecessarilythesameperceptionsunderthesamecircumstances。Sect。20。Wemustconsequentlyanalyzeexperienceinordertoseewhatiscontainedinthisproductofthesensesandoftheunderstanding，andhowthejudgmentofexperienceitselfispossible。ThefoundationistheintuitionofwhichIbecomeconscious，i。e。，perception（perceptio），whichpertainsmerelytothesenses。Butinthenextplace，thereareactsofjudging（whichbelongonlytotheunderstanding）。Butthisjudgingmaybetwofold—first，Imaymerelycompareperceptionsandconnecttheminaparticularstateofmyconsciousness;or，secondly，Imayconnecttheminconsciousnessgenerally。Theformerjudgmentismerelyajudgmentofperception，andofsubjectivevalidityonly：itismerelyaconnectionofperceptionsinmymentalstate，withoutreferencetotheobject。Henceitisnot，asiscommonlyimagined，enoughforexperiencetocompareperceptionsandtoconnecttheminconsciousnessthroughjudgment;therearisesnouniversalityandnecessity，forwhichalonejudgmentscanbecomeobjectivelyvalidandbecalledexperience。Quiteanotherjudgmentthereforeisrequiredbeforeperceptioncanbecomeexperience。Thegivenintuitionmustbesubsumedunderaconcept，whichdeterminestheformofjudgingingeneralrelativelytotheintuition，connectsitsempiricalconsciousnessinconsciousnessgenerally，andtherebyprocuresuniversalvalidityforempiricaljudgments。AconceptofthisnatureisapureaprioriconceptoftheUnderstanding，whichdoesnothingbutdetermineforanintuitionthegeneralwayinwhichitcanbeusedforjudgments。Lettheconceptbethatofcause，thenitdeterminedtheintuitionwhichissubsumedunderit，e。g。，thatofair，relativetojudgmentsingeneral，viz。，theconceptofairserveswithregardtoitsexpansionintherelationofantecedenttoconsequentinahypotheticaljudgment。Theconceptofcauseaccordinglyisapureconceptoftheunderstanding，whichistotallydisparatefromallpossibleperception，andonlyservestodeterminetherepresentationsubsumedunderit，relativelytojudgmentsingeneral，andsotomakeauniversallyvalidjudgmentpossible。Before，therefore，ajudgmentofperceptioncanbecomeajudgmentofexperience，itisrequisitethattheperceptionshouldbesubsumedundersomesuchaconceptoftheunderstanding。;forinstance，airranksundertheconceptofcauses，whichdeterminesourjudgmentaboutitinregardtoitsexpansionashypothetical。10Therebytheexpansionoftheairisrepresentednotasmerelybelongingtotheperceptionoftheairinmypresentstateorinseveralstatesofmine，orinthestateofperceptionofothers，butasbelongingtoitnecessarily。Thejudgment，\"theairiselastic，\" becomesuniversallyvalid，andajudgmentofexperience，onlybycertainjudgmentsprecedingit，whichsubsumetheintuitionofairundertheconceptofcauseandeffect：andtheytherebydeterminetheperceptionsnotmerelyasregardsoneanotherinme，butrelativelytotheformofjudgingingeneral，whichisherehypothetical，andinthiswaytheyrendertheempiricaljudgmentuniversallyvalid。Ifalloursyntheticaljudgmentsareanalyzedsofarastheyareobjectivelyvalid，itwillbefoundthattheyneverconsistofmereintuitionsconnectedonly（asiscommonlybelieved）bycomparisonintoajudgment;butthattheywouldbeimpossiblewerenotapureconceptoftheunderstandingsuperaddedtotheconceptsabstractedfromintuition，underwhichconcepttheselatteraresubsumed，andinthismanneronlycombinedintoanobjectivelyvalidjudgment。Eventhejudgmentsofpuremathematicsintheirsimplestaxiomsarenotexemptfromthiscondition。Theprinciple，IIastraightlineistheshortestbetweentwopoints，\"presupposesthatthelineissubsumedundertheconceptofquantity，whichcertainlyisnomereintuition，butbasitsseatintheunderstandingalone，andservestodeterminetheintuition（oftheline）withregardtothejudgmentswhichmaybemadeaboutit，relativelytotheirquantity，thatis，toplurality（asjudiciaplurativa）。11Forunderthemitisunderstoodthatinagivenintuitionthereiscontainedapluralityofhomogenousparts。Sect。21。Toprove，then，thepossibilityofexperiencesofarasitrestsuponpureconceptsoftheunderstandingapriori，wemustfirstrepresentwhatbelongstojudgmentsingeneralandthevariousfunctionsoftheunderstanding，inacompletetable。Forthepureconceptsoftheunderstandingmustrunparalleltothesefunctions，assuchconceptsarenothingmorethanconceptsofintuitionsingeneral，sofarasthesearedeterminedbyoneorotherofthesefunctionsofjudging，inthemselves，thatis，necessarilyanduniversally。Herebyalsotheaprioriprinciplesofthepossibilityofallexperience，asofanobjectivelyvalidempiricalcognition，willbepreciselydetermined。Fortheyarenothingbutpropositionsbywhichallperceptionis（undercertainuniversalconditionsofintuition） subsumedunderthosepureconceptsoftheunderstanding。LOGICALTABLE OFJUDGMENTS。1。AstoQuantity。Universal。Particular。Singular。 2。AstoQuality。Affirmative。Negative。Infinite。 3。AstoRelation。Categorical。Hypothetical。Disjunctive。 4。AstoModality。Problematical。Assertorical。Apodictical。TRANSCENDENTALTABLEOFTHEPURECONCEFITSOFTHEUNDERSTANDING。1。AstoQuantity。Unity（theMeasure）。Plurality（theQuantity）。Totality（theWhole）。 2。AstoQuality。Reality。Negation。Limitation。 3。AstoRelation。Substance。Cause。Community。 4。AstoModality。Possibility。Existence。Necessity。PUREPHYSICALTABLEOFTHEUNIVERSALPRINCIPLESOFTHESCIENCEOFNATURE。1。AxiomsofIntuition。 2。AnticipationsofPerception。 3。AnalogiesofExperience。 4。PostulatesofEmpiricalThinkinggenerally。Sect。21a。Inordertocomprisethewholematterinoneidea，itisfirstnecessarytoremindthereaderthatwearediscussingnottheoriginofexperience，butofthatwhichliesinexperience。Theformerpertainstoempiricalpsychology，andwouldeventhenneverbeadequatelyexplainedwithoutthelatter，whichbelongstotheCritiqueofcognition，andparticularlyoftheunderstanding。Experienceconsistsofintuitions，whichbelongtothesensibility，andofjudgments，whichareentirelyaworkoftheunderstanding。Butthejudgments，whichtheunderstandingformsalonefromsensuousintuitions，arefarfrombeingjudgmentsofexperience。Forintheonecasethejudgmentconnectsonlytheperceptionsastheyaregiveninthesensuousintuition，whileintheotherthejudgmentsmustexpresswhatexperienceingeneral，andnotwhatthemereperception（whichpossessesonlysubjectivevalidity） contains。Thejudgmentofexperiencemustthereforeaddtothesensuousintuitionanditslogicalconnectioninajudgment（afterithasbeenrendereduniversalbycomparison）somethingthatdeterminesthesyntheticaljudgmentasnecessaryandthereforeasuniversallyvalid。Thiscanbenothingelsethanthatconceptwhichrepresentstheintuitionasdeterminedinitselfwithregardtooneformofjudgmentratherthananother，viz。，aconceptofthatsyntheticalunityofintuitionswhichcanonlyberepresentedbyagivenlogicalfunctionofjudgments。Sect。22。Thesumofthematteristhis：thebusinessofthesensesistointuit——thatoftheunderstandingistothink。Butthinkingisunitingrepresentationsinoneconsciousness。Thisunionoriginateseithermerelyrelativetothesubject，andisaccidentalandsubjective，orisabsolute，andisnecessaryorobjective。Theunionofrepresentationsinoneconsciousnessisjudgment。Thinkingthereforeisthesameasjudging，orreferringrepresentationstojudgmentsingeneral。Hencejudgmentsareeithermerelysubjective，whenrepresentationsarereferredtoaconsciousnessinonesubjectonly，andunitedinit，orobjective，whentheyareunitedinaconsciousnessgenerally，thatis，necessarily。Thelogicalfunctionsofalljudgmentsarebutvariousmodesofunitingrepresentationsinconsciousness。Butiftheyserveforconcepts，theyareconceptsoftheirnecessaryunioninaconsciousness，andsoprinciplesofobjectivelyvalidjudgments。Thisunioninaconsciousnessiseitheranalytical，byidentity，orsynthetical，bythecombinationandadditionofvariousrepresentationsonetoanother。 Experienceconsistsinthesyntheticalconnectionofphenomena（perceptions） inconsciousness，sofarasthisconnectionisnecessary。Hencethepureconceptsoftheunderstandingarethoseunderwhichallperceptionsmustbesubsumederetheycanserveforjudgmentsofexperience，inwhichthesyntheticalunityoftheperceptionsisrepresentedasnecessaryanduniversallyvalid。12Sect。23。judgments，whenconsideredmerelyastheconditionoftheunionofgivenrepresentationsinaconsciousness，arerules。Theserules，sofarastheyrepresenttheunionasnecessary，arerulesapriori，andsofarastheycannotbededucedfromhigherrules，arefundamentalprinciples。Butinregardtothepossibilityofallexperience，merelyinrelationtotheformofthinkinginit，noconditionsofjudgmentsofexperiencearehigherthanthosewhichbringthephenomena，accordingtothevariousformoftheirintuition，underpureconceptsoftheunderstanding，andrendertheempiricaljudgmentobjectivelyvalid。Theseconceptsarethereforetheaprioriprinciplesofpossibleexperience。Theprinciplesofpossibleexperiencearethenatthesametimeuniversallawsofnature，whichcanbeknownapriori。Andthustheprobleminoursecondquestion，\"HowisthepureScienceofNaturepossible？\"issolved。Forthesystemwhichisrequiredfortheformofascienceistobemetwithinperfectionhere，because，beyondtheabove—mentionedformalconditionsofalljudgmentsingeneralofferedinlogic，noothersarepossible，andtheseconstitutealogicalsystem。Theconceptsgroundedthereupon，whichcontaintheaprioriconditionsofallsyntheticalandnecessaryjudgments，accordinglyconstituteatranscendentalsystem。 Finallytheprinciples，bymeansofwhichallphenomenaaresubsumedundertheseconcepts，constituteaphysical13system，thatis，asystemofnature，whichprecedesallempiricalcognitionofnature，makesitevenpossible，andhencemayinstrictnessbedenominatedtheuniversalandpurescienceofnature。Sect。24。Thefirstone14ofthephysiologicalprinciplessubsumesallphenomena，asintuitionsinspaceandtime，undertheconceptofQuantity，andissofaraprincipleoftheapplicationofMathematicstoexperience。 Thesecondonesubsumestheempiricalelement，viz。，sensation，whichdenotestherealinintuitions，notindeeddirectlyundertheconceptofquantity，becausesensationisnotanintuitionthatcontainseitherspaceortime，thoughitplacestherespectiveobjectintoboth。Butstillthereisbetweenreality（sense—representation）andthezero，ortotalvoidofintuitionintime，adifferencewhichhasaquantity。Forbetweeneverygivendegreeoflightandofdarkness，betweeneverydegreeofbeatandofabsolutecold，betweeneverydegreeofweightandofabsolutelightness，betweeneverydegreeofoccupiedspaceandoftotallyvoidspace，diminishingdegreescanbeconceived，inthesamemannerasbetweenconsciousnessandtotalunconsciousness（thedarknessofapsychologicalblank）everdiminishingdegreesobtain。Hencethereisnoperceptionthatcanproveanabsoluteabsenceofit;forinstance，nopsychologicaldarknessthatcannotbeconsideredasakindofconsciousness，whichisonlyout—balancedbyastrongerconsciousness。 Thisoccursinallcasesofsensation，andsotheunderstandingcananticipateevensensations，whichconstitutethepeculiarqualityofempiricalrepresentations（appearances），bymeansoftheprinciple：\"thattheyallhave（consequentlythatwhatisrealinallphenomenahas）adegree。\"Hereisthesecondapplicationofmathematics（mathesisintensortim）tothescienceofnature。Sect。25。Anenttherelationofappearancesmerelywithaviewtotheirexistence，thedeterminationisnotmathematicalbutdynamical，andcanneverbeobjectivelyvalid，consequentlyneverfitforexperience，ifitdoesnotcomeunderaprioriprinciplesbywhichthecognitionofexperiencerelativetoappearancesbecomesevenpossible。HenceappearancesmustbesubsumedundertheconceptofSubstance，whichisthefoundationofalldeterminationofexistence，asaconceptofthethingitself;orsecondlysofarasasuccessionisfoundamongphenomena，thatis，anevent—undertheconceptofanEffectwithreferencetoCause;orlastly—sofarascoexistenceistobeknownobjectively，thatis，byajudgmentofexperience—undertheconceptofCommunity（actionandreaction）。15Thusaprioriprinciplesformthebasisofobjectivelyvalid，thoughempiricaljudgments，thatis，ofthepossibilityofexperiencesofarasitmustconnectobjectsasexistinginnature。Theseprinciplesaretheproperlawsofnature，whichmaybetermeddynamical。Finallythecognitionoftheagreementandconnectionnotonlyofappearancesamongthemselvesinexperience，butoftheirrelationtoexperienceingeneral，belongstothejudgmentsofexperience。Thisrelationcontainseithertheiragreementwiththeformalconditions，whichtheunderstandingknows，ortheircoherencewiththematerialsofthesensesandofperception，orcombinesbothintooneconcept。ConsequentlyitcontainsPossibility，Actuality，andNecessityaccordingtouniversallawsofnature;andthisconstitutesthephysicaldoctrineofmethod，orthedistinctionoftruthandofhypotheses，andtheboundsofthecertaintyofthelatter。Sect。26。ThethirdtableofPrinciplesdrawnfromthenatureoftheunderstandingitselfafterthecriticalmethod，showsaninherentperfection，whichraisesitfaraboveeveryothertablewhichhashithertothoughinvainbeentriedormayyetbetriedbyanalyzingtheobjectsthemselvesdogmatically。Itexhibitsallsyntheticalaprioriprinciplescompletelyandaccordingtooneprinciple，viz。，thefacultyofjudgingingeneral，constitutingtheessenceofexperienceasregardstheunderstanding，sothatwecanbecertainthattherearenomoresuchprinciples，whichaffordsasatisfactionsuchascanneverbeattainedbythedogmaticalmethod。Yetisthisnotall：thereisastillgreatermeritinit。Wemustcarefullybearinmindtheproofwhichshowsthepossibilityofthiscognitionapriori，andatthesametimelimitsallsuchprinciplestoaconditionwhichmustneverbelostsightof，ifwedesireitnottobemisunderstood，andextendedinusebeyondtheoriginalsensewhichtheunderstandingattachestoit。ThislimitisthattheycontainnothingbuttheconditionsofpossibleexperienceingeneralsofarasitisSubjectedtolawsapriori。ConsequentlyIdonotsay，thatthingsinthemselvespossessaquantity，thattheiractualitypossessesadegree，theirexistenceaconnectionofaccidentsinasubstance，etc。Thisnobodycanprove，becausesuchasyntheticalconnectionfrommereconcepts，withoutanyreferencetosensuousintuitionontheoneside，orconnectionofitinapossibleexperienceontheother，isabsolutelyimpossible。Theessentiallimitationoftheconceptsintheseprinciplesthenis：Thatallthingsstandnecessarilyaprioriundertheaforementionedconditions，asobjectsofexperienceonly。Hencetherefollowssecondlyaspecificallypeculiarmodeofproofoftheseprinciples：theyarenotdirectlyreferredtoappearancesandtotheirrelations，buttothepossibilityofexperience，ofwhichappearancesconstitutethematteronly，nottheform。Thustheyarereferredtoobjectivelyanduniversallyvalidsyntheticalpropositions，inwhichwedistinguishjudgmentsofexperiencefromthoseofperception。Thistakesplacebecauseappearances，asmereintuitions，occupyingapartofspaceandtime，comeundertheconceptofQuantity，whichunitestheirmultiplicityaprioriaccordingtorulessynthetically。Again，sofarastheperceptioncontains，besidesintuition，sensibility，andbetweenthelatterandnothing（i。e。，thetotaldisappearanceofsensibility），thereisanever—decreasingtransition，itisapparentthatthatwhichisinappearancesmusthaveadegree，sofarasit（viz。，theperception）doesnotitselfoccupyanypartofspaceoroftime。16Stillthetransitiontoactualityfromemptytimeoremptyspaceisonlypossibleintime;consequentlythoughsensibility，asthequalityofempiricalintuition，canneverbeknownapriori，byitsspecificdifferencefromothersensibilities，yetitcan，inapossibleexperienceingeneral，asaquantityofperceptionbeintenselydistinguishedfromeveryothersimilarperception。Hencetheapplicationofmathematicstonature，asregardsthesensuousintuitionbywhichnatureisgiventous，becomespossibleandisthusdetermined。Aboveall，thereadermustpayattentiontothemodeofproofoftheprincipleswhichoccurunderthetitleofAnalogiesofexperience。Forthesedonotrefertothegenesisofintuitions，asdotheprinciplesofappliedmathematics，buttotheconnectionoftheirexistenceinexperience;andthiscanbenothingbutthedeterminationoftheirexistenceintimeaccordingtonecessarylaws，underwhichalonetheconnectionisobjectivelyvalid，andthusbecomesexperience。Theproofthereforedoesnotturnonthesyntheticalunityintheconnectionofthingsinthemselves，butmerelyofperceptions，andofthesenotinregardtotheirmatter，buttothedeterminationoftimeandoftherelationoftheirexistenceinit，accordingtouniversallaws。 Iftheempiricaldeterminationinrelativetimeisindeedobjectivelyvalid（i。e。，experience），theseuniversallawscontainthenecessarydeterminationofexistenceintimegenerally（viz。，accordingtoaruleoftheunderstandingapriori）。IntheseProlegomenaIcannotfurtherdescantonthesubject，butmyreader（whohasprobablybeenlongaccustomedtoconsiderexperienceamereempiricalsynthesisofperceptions，andhencenotconsideredthatitgoesmuchbeyondthem，asitimpartstoempiricaljudgmentsuniversalvalidity，andforthatpurposerequiresapureandaprioriunityoftheunderstanding） isrecommendedtopayspecialattentiontothisdistinctionofexperiencefromamereaggregateofperceptions，andtojudgethemodeofprooffromthispointofview。Sect。27。NowwearepreparedtoremoveHume’sdoubt。Hejustlymaintains，thatwecannotcomprehendbyreasonthepossibilityofCausality，thatis，ofthereferenceoftheexistenceofonethingtotheexistenceofanother，whichisnecessitatedbytheformer。Iadd，thatwecomprehendjustaslittletheconceptofSubsistence，thatis，thenecessitythatatthefoundationoftheexistenceofthingsthereliesasubjectwhichcannotitselfbeapredicateofanyotherthing;nay，wecannotevenformanotionofthepossibilityofsuchathing（thoughwecanpointoutexamplesofitsuseinexperience）。TheverysameincomprehensibilityaffectstheCommunityofthings，aswecannotcomprehendbowfromthestateofonethinganinferencetothestateofquiteanotherthingbeyondit，andviceversa，canbedrawn，andhowsubstanceswhichhaveeachtheirownseparateexistenceshoulddependupononeanothernecessarily。ButIamveryfarfromholdingtheseconceptstobederivedmerelyfromexperience，andthenecessityrepresentedinthem，tobeimaginaryandamereillusionproducedinusbylonghabit。Onthecontrary，Ihaveamplyshown，thattheyandthetheoremsderivedfromthemarefirmlyestablishedapriori，orbeforeallexperience，andhavetheirundoubtedobjectivevalue，thoughonlywithregardtoexperience。Sect。28。ThoughIhavenonotionofsuchaconnectionofthingsinthemselves，thattheycaneitherexistassubstances，oractascauses，orstandincommunitywithothers（aspartsofarealwhole），andIcanjustaslittleconceivesuchpropertiesinappearancesassuch（becausethoseconceptscontainnothingthatliesintheappearances，butonlywhattheunderstandingalonemustthink）：wehaveyetanotionofsuchaconnectionofrepresentationsinourunderstanding，andinjudgmentsgenerally;consistinginthisthatrepresentationsappearinonesortofjudgmentsassubjectinrelationtopredicates，inanotherasreasoninrelationtoconsequences，andinathirdasparts，whichconstitutetogetheratotalpossiblecognition。 Besidesweknowapriorithatwithoutconsideringtherepresentationofanobjectasdeterminedinsomeoftheserespects，wecanhavenovalidcognitionoftheobject，and，ifweshouldoccupyourselvesabouttheobjectinitself，thereisnopossibleattribute，bywhichIcouldknowthatitisdeterminedunderanyoftheseaspects，thatis，undertheconcepteitherofsubstance，orofcause，or（inrelationtoothersubstances）ofcommunity，forIhavenonotionofthepossibilityofsuchaconnectionofexistence。 Butthequestionisnothowthingsinthemselves，buthowtheempiricalcognitionofthingsisdeterminedasregardstheaboveaspectsofjudgmentsingeneral，thatis，howthings，asobjectsofexperience，canandshallbesubsumedundertheseconceptsoftheunderstanding。Andthenitisclear，thatIcompletelycomprehendnotonlythepossibility，butalsothenecessityofsubsumingallphenomenaundertheseconcepts，thatis，ofusingthemforprinciplesofthepossibilityofexperience。Sect。29。WhenmakinganexperimentwithHume’sproblematicalconcept（hiscruxmetaphysicorum），theconceptofcause，wehave，inthefirstplace，givenapriori，bymeansoflogic，theformofaconditionaljudgmentingeneral，i。e。，wehaveonegivencognitionasantecedentandanotherasconsequence。Butitispossible，thatinperceptionwemaymeetwitharuleofrelation，whichrunsthus：thatacertainphenomenonisconstantlyfollowedbyanother（thoughnotconversely），andthisisacaseformetousethehypotheticaljudgment，and，forinstance，tosay，ifthesunshineslongenoughuponabody，itgrowswarm。Herethereisindeedasyetnonecessityofconnection，orconceptofcause。ButIproceedandsay，thatifthisproposition，whichismerelyasubjectiveconnectionofperceptions，istobeajudgmentofexperience，itmustbeconsideredasnecessaryanduniversallyvalid。Suchapropositionwouldbe，IIthesunisbyitslightthecauseofheat。\"Theempiricalruleisnowconsideredasalaw，andasvalidnotmerelyofappearancesbutvalidofthemforthepurposesofapossibleexperiencewhichrequiresuniversalandthereforenecessarilyvalidrules。Ithereforeeasilycomprehendtheconceptofcause，asaconceptnecessarilybelongingtothemereformofexperience，anditspossibilityasasyntheticalunionofperceptionsinconsciousnessgenerally;butIdonotatallcomprehendthepossibilityofathinggenerallyasacause，becausetheconceptofcausedenotesaconditionnotatallbelongingtothings，buttoexperience。Itisnothinginfactbutanobjectivelyvalidcognitionofappearancesandoftheirsuccession，sofarastheantecedentcanbeconjoinedwiththeconsequentaccordingtotheruleofhypotheticaljudgments。Sect。30。Henceifthepureconceptsoftheunderstandingdonotrefertoobjectsofexperiencebuttothingsinthemselves（noumena），theyhavenosignificationwhatever。Theyserve，asitwere，onlytodecipherappearances，thatwemaybeabletoreadthemasexperience。