the critique of pure reason-第56章

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cogitated　by　means　of　an　a　priori　synthetical　conception；　if　not　in

the　synthesis　which　constitutes　the　form　of　empirical　cognition　of

objects？　That　in　such　a　conception　no　contradiction　exists　is　indeed　a

necessary　logical　condition；　but　very　far　from　being　sufficient　to

establish　the　objective　reality　of　the　conception；　that　is；　the

possibility　of　such　an　object　as　is　thought　in　the　conception。　Thus；

in　the　conception　of　a　figure　which　is　contained　within　two　straight

lines；　there　is　no　contradiction；　for　the　conceptions　of　two

straight　lines　and　of　their　junction　contain　no　negation　of　a

figure。　The　impossibility　in　such　a　case　does　not　rest　upon　the

conception　in　itself；　but　upon　the　construction　of　it　in　space；　that

is　to　say；　upon　the　conditions　of　space　and　its　determinations。　But

these　have　themselves　objective　reality；　that　is；　they　apply　to

possible　things；　because　they　contain　a　priori　the　form　of

experience　in　general。

　　And　now　we　shall　proceed　to　point　out　the　extensive　utility　and

influence　of　this　postulate　of　possibility。　When　I　represent　to　myself

a　thing　that　is　permanent；　so　that　everything　in　it　which　changes

belongs　merely　to　its　state　or　condition；　from　such　a　conception　alone

I　never　can　cognize　that　such　a　thing　is　possible。　Or；　if　I

represent　to　myself　something　which　is　so　constituted　that；　when　it　is

posited；　something　else　follows　always　and　infallibly；　my　thought

contains　no　self…contradiction；　but　whether　such　a　property　as

causality　is　to　be　found　in　any　possible　thing；　my　thought　alone

affords　no　means　of　judging。　Finally；　I　can　represent　to　myself

different　things　（substances）　which　are　so　constituted　that　the

state　or　condition　of　one　causes　a　change　in　the　state　of　the　other；

and　reciprocally；　but　whether　such　a　relation　is　a　property　of

things　cannot　be　perceived　from　these　conceptions；　which　contain　a

merely　arbitrary　synthesis。　Only　from　the　fact；　therefore；　that

these　conceptions　express　a　priori　the　relations　of　perceptions　in

every　experience；　do　we　know　that　they　possess　objective　reality；　that

is；　transcendental　truth；　and　that　independent　of　experience；　though

not　independent　of　all　relation　to　form　of　an　experience　in　general

and　its　synthetical　unity；　in　which　alone　objects　can　be　empirically

cognized。

　　But　when　we　fashion　to　ourselves　new　conceptions　of　substances；

forces；　action；　and　reaction；　from　the　material　presented　to　us　by

perception；　without　following　the　example　of　experience　in　their

connection；　we　create　mere　chimeras；　of　the　possibility　of　which　we

cannot　discover　any　criterion；　because　we　have　not　taken　experience

for　our　instructress；　though　we　have　borrowed　the　conceptions　from

her。　Such　fictitious　conceptions　derive　their　character　of　possibility

not；　like　the　categories；　a　priori；　as　conceptions　on　which　all

experience　depends；　but　only；　a　posteriori；　as　conceptions　given　by

means　of　experience　itself；　and　their　possibility　must　either　be

cognized　a　posteriori　and　empirically；　or　it　cannot　be　cognized　at

all。　A　substance　which　is　permanently　present　in　space；　yet　without

filling　it　（like　that　tertium　quid　between　matter　and　the　thinking

subject　which　some　have　tried　to　introduce　into　metaphysics）；　or　a

peculiar　fundamental　power　of　the　mind　of　intuiting　the　future　by

anticipation　（instead　of　merely　inferring　from　past　and　present

events）；　or；　finally；　a　power　of　the　mind　to　place　itself　in　community

of　thought　with　other　men；　however　distant　they　may　be…　these　are

conceptions　the　possibility　of　which　has　no　ground　to　rest　upon。　For

they　are　not　based　upon　experience　and　its　known　laws；　and；　without

experience；　they　are　a　merely　arbitrary　conjunction　of　thoughts；

which；　though　containing　no　internal　contradiction；　has　no　claim　to

objective　reality；　neither；　consequently；　to　the　possibility　of　such

an　object　as　is　thought　in　these　conceptions。　As　far　as　concerns

reality；　it　is　self…evident　that　we　cannot　cogitate　such　a　possibility

in　concreto　without　the　aid　of　experience；　because　reality　is

concerned　only　with　sensation；　as　the　matter　of　experience；　and　not

with　the　form　of　thought；　with　which　we　can　no　doubt　indulge　in

shaping　fancies。

　　But　I　pass　by　everything　which　derives　its　possibility　from

reality　in　experience；　and　I　purpose　treating　here　merely　of　the

possibility　of　things　by　means　of　a　priori　conceptions。　I　maintain；

then；　that　the　possibility　of　things　is　not　derived　from　such

conceptions　per　se；　but　only　when　considered　as　formal　and　objective

conditions　of　an　experience　in　general。

　　It　seems；　indeed；　as　if　the　possibility　of　a　triangle　could　be

cognized　from　the　conception　of　it　alone　（which　is　certainly

independent　of　experience）；　for　we　can　certainly　give　to　the

conception　a　corresponding　object　completely　a　priori；　that　is　to　say；

we　can　construct　it。　But　as　a　triangle　is　only　the　form　of　an

object；　it　must　remain　a　mere　product　of　the　imagination；　and　the

possibility　of　the　existence　of　an　object　corresponding　to　it　must

remain　doubtful；　unless　we　can　discover　some　other　ground；　unless　we

know　that　the　figure　can　be　cogitated　under　the　conditions　upon

which　all　objects　of　experience　rest。　Now；　the　facts　that　space　is　a

formal　condition　a　priori　of　external　experience；　that　the　formative

synthesis；　by　which　we　construct　a　triangle　in　imagination；　is　the

very　same　as　that　we　employ　in　the　apprehension　of　a　phenomenon　for

the　purpose　of　making　an　empirical　conception　of　it；　are　what　alone

connect　the　notion　of　the　possibility　of　such　a　thing；　with　the

conception　of　it。　In　the　same　manner；　the　possibility　of　continuous

quantities；　indeed　of　quantities　in　general；　for　the　conceptions　of

them　are　without　exception　synthetical；　is　never　evident　from　the

conceptions　in　themselves；　but　only　when　they　are　considered　as　the

formal　conditions　of　the　determination　of　objects　in　experience。　And

where；　indeed；　should　we　look　for　objects　to　correspond　to　our

conceptions；　if　not　in　experience；　by　which　alone　objects　are

presented　to　us？　It　is；　however；　true　that　without　antecedent

experience　we　can　cognize　and　characterize　the　possibility　of

things；　relatively　to　the　formal　conditions；　under　which　something

is　determined　in　experience　as　an　object；　consequently；　completely　a

priori。　But　still　this　is　possible　only　in　relation　to　experience

and　within　its　limits。

　　The　postulate　concerning　the　cognition　of　the　reality　of　things

requires　perception；　consequently　conscious　sensation；　not　indeed

immediately；　that　is；　of　the　object　itself；　whose　existence　is　to　be

cognized；　but　still　that　the　object　have　some　connection　with　a　real

perception；　in　accordance　with　the　analogies　of　experience；　which

exhibit　all　kinds　of　real　connection　in　experience。

　　From　the　mere　conception　of　a　thing　it　is　impossible　to　conclude　its

existence。　For；　let　the　conception　be　ever　so　complete；　and　containing

a　statement　of　all　the　determinations　of　the　thing；　the　existence　of

it　has　nothing　to　do　with　all　this；　but　only　with　thew　question

whether　such　a　thing　is　given；　so　that　the　perception　of　it　can　in

every　case　precede　the　conception。　For　the　fact　that　the　conception　of

it　precedes　the　perception；　merely　indicates　the　possibility　of　its

existence；　it　is　perception　which　presents　matter　to　the　conception；

that　is　the　sole　criterion　of　reality。　Prior　to　the　perception　of

the　thing；　however；　and　therefore　comparatively　a　priori；　we　are

able　to　cognize　its　existence；　provided　it　stands　in　connection　with

some　perceptions　according　to　the　principles　of　the　empirical

conjunction　of　these；　that　is；　in　conformity　with　the　analogies　of

perception。　For；　in　this　case；　the　existence　of　the　supposed　thing

is　connected　with　our　perception　in　a　possible　experience；　and　we

are　able；　with　the　guidance　of　these　analogies；　to　reason　in　the

series　of　possible　perceptions　from　a　thing　which　we　do　really

perceive　to　the　thing　we　do　not　perceive。　Thus