posterior analytics-第17章

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the　basic　truths　of　all　knowledge　are　within　one　genus；　special



premisses　are　required　to　prove　special　conclusions。　But　that　this



cannot　be　the　case　has　been　shown　by　our　proof　that　the　basic　truths



of　things　generically　different　themselves　differ　generically。　For



fundamental　truths　are　of　two　kinds；　those　which　are　premisses　of



demonstration　and　the　subject…genus；　and　though　the　former　are　common；



the　latter…number；　for　instance；　and　magnitude…are　peculiar。







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　　Scientific　knowledge　and　its　object　differ　from　opinion　and　the



object　of　opinion　in　that　scientific　knowledge　is　commensurately



universal　and　proceeds　by　necessary　connexions；　and　that　which　is



necessary　cannot　be　otherwise。　So　though　there　are　things　which　are



true　and　real　and　yet　can　be　otherwise；　scientific　knowledge　clearly



does　not　concern　them：　if　it　did；　things　which　can　be　otherwise



would　be　incapable　of　being　otherwise。　Nor　are　they　any　concern　of



rational　intuition…by　rational　intuition　I　mean　an　originative



source　of　scientific　knowledge…nor　of　indemonstrable　knowledge；



which　is　the　grasping　of　the　immediate　premiss。　Since　then　rational



intuition；　science；　and　opinion；　and　what　is　revealed　by　these



terms；　are　the　only　things　that　can　be　'true'；　it　follows　that　it　is



opinion　that　is　concerned　with　that　which　may　be　true　or　false；　and



can　be　otherwise：　opinion　in　fact　is　the　grasp　of　a　premiss　which　is



immediate　but　not　necessary。　This　view　also　fits　the　observed　facts；



for　opinion　is　unstable；　and　so　is　the　kind　of　being　we　have　described



as　its　object。　Besides；　when　a　man　thinks　a　truth　incapable　of　being



otherwise　he　always　thinks　that　he　knows　it；　never　that　he　opines



it。　He　thinks　that　he　opines　when　he　thinks　that　a　connexion；　though



actually　so；　may　quite　easily　be　otherwise；　for　he　believes　that



such　is　the　proper　object　of　opinion；　while　the　necessary　is　the



object　of　knowledge。



　　In　what　sense；　then；　can　the　same　thing　be　the　object　of　both



opinion　and　knowledge？　And　if　any　one　chooses　to　maintain　that　all



that　he　knows　he　can　also　opine；　why　should　not　opinion　be



knowledge？　For　he　that　knows　and　he　that　opines　will　follow　the　same



train　of　thought　through　the　same　middle　terms　until　the　immediate



premisses　are　reached；　because　it　is　possible　to　opine　not　only　the



fact　but　also　the　reasoned　fact；　and　the　reason　is　the　middle　term；　so



that；　since　the　former　knows；　he　that　opines　also　has　knowledge。



　　The　truth　perhaps　is　that　if　a　man　grasp　truths　that　cannot　be　other



than　they　are；　in　the　way　in　which　he　grasps　the　definitions　through



which　demonstrations　take　place；　he　will　have　not　opinion　but



knowledge：　if　on　the　other　hand　he　apprehends　these　attributes　as



inhering　in　their　subjects；　but　not　in　virtue　of　the　subjects'



substance　and　essential　nature　possesses　opinion　and　not　genuine



knowledge；　and　his　opinion；　if　obtained　through　immediate　premisses；



will　be　both　of　the　fact　and　of　the　reasoned　fact；　if　not　so　obtained；



of　the　fact　alone。　The　object　of　opinion　and　knowledge　is　not　quite



identical；　it　is　only　in　a　sense　identical；　just　as　the　object　of　true



and　false　opinion　is　in　a　sense　identical。　The　sense　in　which　some



maintain　that　true　and　false　opinion　can　have　the　same　object　leads



them　to　embrace　many　strange　doctrines；　particularly　the　doctrine　that



what　a　man　opines　falsely　he　does　not　opine　at　all。　There　are　really



many　senses　of　'identical'；　and　in　one　sense　the　object　of　true　and



false　opinion　can　be　the　same；　in　another　it　cannot。　Thus；　to　have　a



true　opinion　that　the　diagonal　is　commensurate　with　the　side　would



be　absurd：　but　because　the　diagonal　with　which　they　are　both　concerned



is　the　same；　the　two　opinions　have　objects　so　far　the　same：　on　the



other　hand；　as　regards　their　essential　definable　nature　these



objects　differ。　The　identity　of　the　objects　of　knowledge　and　opinion



is　similar。　Knowledge　is　the　apprehension　of；　e。g。　the　attribute



'animal'　as　incapable　of　being　otherwise；　opinion　the　apprehension



of　'animal'　as　capable　of　being　otherwise…e。g。　the　apprehension　that



animal　is　an　element　in　the　essential　nature　of　man　is　knowledge；



the　apprehension　of　animal　as　predicable　of　man　but　not　as　an



element　in　man's　essential　nature　is　opinion：　man　is　the　subject　in



both　judgements；　but　the　mode　of　inherence　differs。



　　This　also　shows　that　one　cannot　opine　and　know　the　same　thing



simultaneously；　for　then　one　would　apprehend　the　same　thing　as　both



capable　and　incapable　of　being　otherwise…an　impossibility。　Knowledge



and　opinion　of　the　same　thing　can　co…exist　in　two　different　people



in　the　sense　we　have　explained；　but　not　simultaneously　in　the　same



person。　That　would　involve　a　man's　simultaneously　apprehending；　e。g。



（1）　that　man　is　essentially　animal…i。e。　cannot　be　other　than



animal…and　（2）　that　man　is　not　essentially　animal；　that　is；　we　may



assume；　may　be　other　than　animal。



　　Further　consideration　of　modes　of　thinking　and　their　distribution



under　the　heads　of　discursive　thought；　intuition；　science；　art；



practical　wisdom；　and　metaphysical　thinking；　belongs　rather　partly



to　natural　science；　partly　to　moral　philosophy。







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　　Quick　wit　is　a　faculty　of　hitting　upon　the　middle　term



instantaneously。　It　would　be　exemplified　by　a　man　who　saw　that　the



moon　has　her　bright　side　always　turned　towards　the　sun；　and　quickly



grasped　the　cause　of　this；　namely　that　she　borrows　her　light　from　him；



or　observed　somebody　in　conversation　with　a　man　of　wealth　and



divined　that　he　was　borrowing　money；　or　that　the　friendship　of　these



people　sprang　from　a　common　enmity。　In　all　these　instances　he　has　seen



the　major　and　minor　terms　and　then　grasped　the　causes；　the　middle



terms。



　　Let　A　represent　'bright　side　turned　sunward'；　B　'lighted　from　the



sun'；　C　the　moon。　Then　B；　'lighted　from　the　sun'　is　predicable　of　C；



the　moon；　and　A；　'having　her　bright　side　towards　the　source　of　her



light'；　is　predicable　of　B。　So　A　is　predicable　of　C　through　B。











　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　Book　II



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　　THE　kinds　of　question　we　ask　are　as　many　as　the　kinds　of　things



which　we　know。　They　are　in　fact　four：…（1）　whether　the　connexion　of



an　attribute　with　a　thing　is　a　fact；　（2）　what　is　the　reason　of　the



connexion；　（3）　whether　a　thing　exists；　（4）　What　is　the　nature　of　the



thing。　Thus；　when　our　question　concerns　a　complex　of　thing　and



attribute　and　we　ask　whether　the　thing　is　thus　or　otherwise



qualified…whether；　e。g。　the　sun　suffers　eclipse　or　not…then　we　are



asking　as　to　the　fact　of　a　connexion。　That　our　inquiry　ceases　with　the



discovery　that　the　sun　does　suffer　eclipse　is　an　indication　of　this；



and　if　we　know　from　the　start　that　the　sun　suffers　eclipse；　we　do



not　inquire　whether　it　does　so　or　not。　On　the　other　hand；　when　we　know



the　fact　we　ask　the　reason；　as；　for　example；　when　we　know　that　the　sun



is　being　eclipsed　and　that　an　earthquake　is　in　progress；　it　is　the



reason　of　eclipse　or　earthquake　into　which　we　inquire。



　　Where　a　complex　is　concerned；　then；　those　are　the　two　questions　we



ask；　but　for　some　objects　of　inquiry　we　have　a　different　kind　of



question　to　ask；　such　as　whether　there　is　or　is　not　a　centaur　or　a



God。　（By　'is　or　is　not'　I　mean　'is　or　is　not；　without　further



qualification'；　as　opposed　to　'is　or　is　not　＇e。g。＇　white'。）　On　the



other　hand；　when　we　have　ascertained　the　thing's　existence；　we　inquire



as　to　its　nature；　asking；　for　instance；　'wh