the critique of pure reason-第9章

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supplied；　at　the　pleasure　of　the　reader；　by　a　comparison　with　the

first　edition；　and　will；　I　hope；　be　more　than　compensated　for　by　the

greater　clearness　of　the　exposition　as　it　now　stands。

　　I　have　observed；　with　pleasure　and　thankfulness；　in　the　pages　of

various　reviews　and　treatises；　that　the　spirit　of　profound　and

thorough　investigation　is　not　extinct　in　Germany；　though　it　may　have

been　overborne　and　silenced　for　a　time　by　the　fashionable　tone　of　a

licence　in　thinking；　which　gives　itself　the　airs　of　genius；　and　that

the　difficulties　which　beset　the　paths　of　criticism　have　not　prevented

energetic　and　acute　thinkers　from　making　themselves　masters　of　the

science　of　pure　reason　to　which　these　paths　conduct…　a　science　which

is　not　popular；　but　scholastic　in　its　character；　and　which　alone　can

hope　for　a　lasting　existence　or　possess　an　abiding　value。　To　these

deserving　men；　who　so　happily　combine　profundity　of　view　with　a　talent

for　lucid　exposition…　a　talent　which　I　myself　am　not　conscious　of

possessing…　I　leave　the　task　of　removing　any　obscurity　which　may　still

adhere　to　the　statement　of　my　doctrines。　For；　in　this　case；　the　danger

is　not　that　of　being　refuted；　but　of　being　misunderstood。　For　my　own

part；　I　must　henceforward　abstain　from　controversy；　although　I　shall

carefully　attend　to　all　suggestions；　whether　from　friends　or

adversaries；　which　may　be　of　use　in　the　future　elaboration　of　the

system　of　this　propaedeutic。　As；　during　these　labours；　I　have　advanced

pretty　far　in　years　this　month　I　reach　my　sixty…fourth　year…　it　will

be　necessary　for　me　to　economize　time；　if　I　am　to　carry　out　my　plan　of

elaborating　the　metaphysics　of　nature　as　well　as　of　morals；　in

confirmation　of　the　correctness　of　the　principles　established　in

this　Critique　of　Pure　Reason；　both　speculative　and　practical；　and　I

must；　therefore；　leave　the　task　of　clearing　up　the　obscurities　of

the　present　work…　inevitable；　perhaps；　at　the　outset…　as　well　as；

the　defence　of　the　whole；　to　those　deserving　men；　who　have　made　my

system　their　own。　A　philosophical　system　cannot　come　forward　armed

at　all　points　like　a　mathematical　treatise；　and　hence　it　may　be

quite　possible　to　take　objection　to　particular　passages；　while　the

organic　structure　of　the　system；　considered　as　a　unity；　has　no

danger　to　apprehend。　But　few　possess　the　ability；　and　still　fewer

the　inclination；　to　take　a　comprehensive　view　of　a　new　system。　By

confining　the　view　to　particular　passages；　taking　these　out　of　their

connection　and　comparing　them　with　one　another；　it　is　easy　to　pick　out

apparent　contradictions；　especially　in　a　work　written　with　any　freedom

of　style。　These　contradictions　place　the　work　in　an　unfavourable　light

in　the　eyes　of　those　who　rely　on　the　judgement　of　others；　but　are

easily　reconciled　by　those　who　have　mastered　the　idea　of　the　whole。　If

a　theory　possesses　stability　in　itself；　the　action　and　reaction

which　seemed　at　first　to　threaten　its　existence　serve　only；　in　the

course　of　time；　to　smooth　down　any　superficial　roughness　or

inequality；　and…　if　men　of　insight；　impartiality；　and　truly　popular

gifts；　turn　their　attention　to　it…　to　secure　to　it；　in　a　short　time；

the　requisite　elegance　also。



　　Konigsberg；　April　1787。

INTRODUCTION

　　　　　　　　　　　　　　　　　　　　　INTRODUCTION。



　　I。　Of　the　difference　between　Pure　and　Empirical　Knowledge



　　That　all　our　knowledge　begins　with　experience　there　can　be　no　doubt。

For　how　is　it　possible　that　the　faculty　of　cognition　should　be

awakened　into　exercise　otherwise　than　by　means　of　objects　which　affect

our　senses；　and　partly　of　themselves　produce　representations；　partly

rouse　our　powers　of　understanding　into　activity；　to　compare　to

connect；　or　to　separate　these；　and　so　to　convert　the　raw　material　of

our　sensuous　impressions　into　a　knowledge　of　objects；　which　is

called　experience？　In　respect　of　time；　therefore；　no　knowledge　of　ours

is　antecedent　to　experience；　but　begins　with　it。

　　But；　though　all　our　knowledge　begins　with　experience；　it　by　no　means

follows　that　all　arises　out　of　experience。　For；　on　the　contrary；　it　is

quite　possible　that　our　empirical　knowledge　is　a　compound　of　that

which　we　receive　through　impressions；　and　that　which　the　faculty　of

cognition　supplies　from　itself　（sensuous　impressions　giving　merely　the

occasion）；　an　addition　which　we　cannot　distinguish　from　the　original

element　given　by　sense；　till　long　practice　has　made　us　attentive　to；

and　skilful　in　separating　it。　It　is；　therefore；　a　question　which

requires　close　investigation；　and　not　to　be　answered　at　first　sight；

whether　there　exists　a　knowledge　altogether　independent　of　experience；

and　even　of　all　sensuous　impressions？　Knowledge　of　this　kind　is　called

a　priori；　in　contradistinction　to　empirical　knowledge；　which　has　its

sources　a　posteriori；　that　is；　in　experience。

　　But　the　expression；　〃a　priori；〃　is　not　as　yet　definite　enough

adequately　to　indicate　the　whole　meaning　of　the　question　above

started。　For；　in　speaking　of　knowledge　which　has　its　sources　in

experience；　we　are　wont　to　say；　that　this　or　that　may　be　known　a

priori；　because　we　do　not　derive　this　knowledge　immediately　from

experience；　but　from　a　general　rule；　which；　however；　we　have　itself

borrowed　from　experience。　Thus；　if　a　man　undermined　his　house；　we　say；

〃he　might　know　a　priori　that　it　would　have　fallen；〃　that　is；　he　needed

not　to　have　waited　for　the　experience　that　it　did　actually　fall。　But

still；　a　priori；　he　could　not　know　even　this　much。　For；　that　bodies

are　heavy；　and；　consequently；　that　they　fall　when　their　supports　are

taken　away；　must　have　been　known　to　him　previously；　by　means　of

experience。

　　By　the　term　〃knowledge　a　priori；〃　therefore；　we　shall　in　the

sequel　understand；　not　such　as　is　independent　of　this　or　that　kind

of　experience；　but　such　as　is　absolutely　so　of　all　experience。　Opposed

to　this　is　empirical　knowledge；　or　that　which　is　possible　only　a

posteriori；　that　is；　through　experience。　Knowledge　a　priori　is

either　pure　or　impure。　Pure　knowledge　a　priori　is　that　with　which　no

empirical　element　is　mixed　up。　For　example；　the　proposition；　〃Every

change　has　a　cause；〃　is　a　proposition　a　priori；　but　impure；　because

change　is　a　conception　which　can　only　be　derived　from　experience。



　　II。　The　Human　Intellect；　even　in　an　Unphilosophical　State；

　　　　　　is　in　Possession　of　Certain　Cognitions　〃a　priori〃。



　　The　question　now　is　as　to　a　criterion；　by　which　we　may　securely

distinguish　a　pure　from　an　empirical　cognition。　Experience　no　doubt

teaches　us　that　this　or　that　object　is　constituted　in　such　and　such

a　manner；　but　not　that　it　could　not　possibly　exist　otherwise。　Now；

in　the　first　place；　if　we　have　a　proposition　which　contains　the　idea

of　necessity　in　its　very　conception；　it　is　a　if；　moreover；　it　is　not

derived　from　any　other　proposition；　unless　from　one　equally

involving　the　idea　of　necessity；　it　is　absolutely　priori。　Secondly；　an

empirical　judgement　never　exhibits　strict　and　absolute；　but　only

assumed　and　comparative　universality　（by　induction）；　therefore；　the

most　we　can　say　is…　so　far　as　we　have　hitherto　observed；　there　is　no

exception　to　this　or　that　rule。　If；　on　the　other　hand；　a　judgement

carries　with　it　strict　and　absolute　universality；　that　is；　admits　of

no　possible　exception；　it　is　not　derived　from　experience；　but　is　valid

absolutely　a　priori。

　　Empirical　universality　is；　therefore；　only　an　arbitrary　extension　of

validity；　from　that　which　may　be　predicated　of　a　proposition　valid

in　most　cases；　to　that　which　is　asserted　of　a　proposition　which

holds　good　in　all；　as；　for　example；　in　the　affirmation；　〃All　bodies

are　heavy。〃　When；　on　the　contrary；　strict　universality　characterizes　a

judgement；　it　necessarily　indicates　another　peculiar　source　of

knowledge；　namely；　a　faculty　of　cognition　a　priori。　Necessity　and

strict　universality；　therefore；　are　infallible　tests　for

distinguishing　pure　from　empirical　knowledge；　and　are　inseparably

connected　with　each　other。