posterior analytics-第24章

按键盘上方向键 ← 或 → 可快速上下翻页，按键盘上的 Enter 键可回到本书目录页，按键盘上方向键 ↑ 可回到本页顶部！
————未阅读完？加入书签已便下次继续阅读！





substance　of　each　subject　is　the　predication　of　elements　in　its



essential　nature　down　to　the　last　differentia　characterizing　the



individuals。　It　follows　that　any　other　synthesis　thus　exhibited　will



likewise　be　identical　with　the　being　of　the　subject。



　　The　author　of　a　hand…book　on　a　subject　that　is　a　generic　whole



should　divide　the　genus　into　its　first　infimae　species…number　e。g。



into　triad　and　dyad…and　then　endeavour　to　seize　their　definitions　by



the　method　we　have　described…the　definition；　for　example；　of



straight　line　or　circle　or　right　angle。　After　that；　having　established



what　the　category　is　to　which　the　subaltern　genus　belongs…quantity



or　quality；　for　instance…he　should　examine　the　properties　'peculiar'



to　the　species；　working　through　the　proximate　common　differentiae。



He　should　proceed　thus　because　the　attributes　of　the　genera　compounded



of　the　infimae　species　will　be　clearly　given　by　the　definitions　of　the



species；　since　the　basic　element　of　them　all　is　the　definition；　i。e。



the　simple　infirma　species；　and　the　attributes　inhere　essentially　in



the　simple　infimae　species；　in　the　genera　only　in　virtue　of　these。



　　Divisions　according　to　differentiae　are　a　useful　accessory　to　this



method。　What　force　they　have　as　proofs　we　did；　indeed；　explain



above；　but　that　merely　towards　collecting　the　essential　nature　they



may　be　of　use　we　will　proceed　to　show。　They　might；　indeed；　seem　to



be　of　no　use　at　all；　but　rather　to　assume　everything　at　the　start



and　to　be　no　better　than　an　initial　assumption　made　without



division。　But；　in　fact；　the　order　in　which　the　attributes　are



predicated　does　make　a　differenceit　matters　whether　we　say



animal…tame…biped；　or　biped…animal…tame。　For　if　every　definable



thing　consists　of　two　elements　and　'animal…tame'　forms　a　unity；　and



again　out　of　this　and　the　further　differentia　man　（or　whatever　else　is



the　unity　under　construction）　is　constituted；　then　the　elements　we



assume　have　necessarily　been　reached　by　division。　Again；　division　is



the　only　possible　method　of　avoiding　the　omission　of　any　element　of



the　essential　nature。　Thus；　if　the　primary　genus　is　assumed　and　we



then　take　one　of　the　lower　divisions；　the　dividendum　will　not　fall



whole　into　this　division：　e。g。　it　is　not　all　animal　which　is　either



whole…winged　or　split…winged　but　all　winged　animal；　for　it　is　winged



animal　to　which　this　differentiation　belongs。　The　primary



differentiation　of　animal　is　that　within　which　all　animal　falls。　The



like　is　true　of　every　other　genus；　whether　outside　animal　or　a



subaltern　genus　of　animal；　e。g。　the　primary　differentiation　of　bird　is



that　within　which　falls　every　bird；　of　fish　that　within　which　falls



every　fish。　So；　if　we　proceed　in　this　way；　we　can　be　sure　that　nothing



has　been　omitted：　by　any　other　method　one　is　bound　to　omit　something



without　knowing　it。



　　To　define　and　divide　one　need　not　know　the　whole　of　existence。　Yet



some　hold　it　impossible　to　know　the　differentiae　distinguishing　each



thing　from　every　single　other　thing　without　knowing　every　single　other



thing；　and　one　cannot；　they　say；　know　each　thing　without　knowing　its



differentiae；　since　everything　is　identical　with　that　from　which　it



does　not　differ；　and　other　than　that　from　which　it　differs。　Now



first　of　all　this　is　a　fallacy：　not　every　differentia　precludes



identity；　since　many　differentiae　inhere　in　things　specifically



identical；　though　not　in　the　substance　of　these　nor　essentially。



Secondly；　when　one　has　taken　one's　differing　pair　of　opposites　and



assumed　that　the　two　sides　exhaust　the　genus；　and　that　the　subject　one



seeks　to　define　is　present　in　one　or　other　of　them；　and　one　has



further　verified　its　presence　in　one　of　them；　then　it　does　not



matter　whether　or　not　one　knows　all　the　other　subjects　of　which　the



differentiae　are　also　predicated。　For　it　is　obvious　that　when　by



this　process　one　reaches　subjects　incapable　of　further　differentiation



one　will　possess　the　formula　defining　the　substance。　Moreover；　to



postulate　that　the　division　exhausts　the　genus　is　not　illegitimate



if　the　opposites　exclude　a　middle；　since　if　it　is　the　differentia　of



that　genus；　anything　contained　in　the　genus　must　lie　on　one　of　the　two



sides。



　　In　establishing　a　definition　by　division　one　should　keep　three



objects　in　view：　（1）　the　admission　only　of　elements　in　the　definable



form；　（2）　the　arrangement　of　these　in　the　right　order；　（3）　the



omission　of　no　such　elements。　The　first　is　feasible　because　one　can



establish　genus　and　differentia　through　the　topic　of　the　genus；　just



as　one　can　conclude　the　inherence　of　an　accident　through　the　topic



of　the　accident。　The　right　order　will　be　achieved　if　the　right　term　is



assumed　as　primary；　and　this　will　be　ensured　if　the　term　selected　is



predicable　of　all　the　others　but　not　all　they　of　it；　since　there



must　be　one　such　term。　Having　assumed　this　we　at　once　proceed　in　the



same　way　with　the　lower　terms；　for　our　second　term　will　be　the　first



of　the　remainder；　our　third　the　first　of　those　which　follow　the　second



in　a　'contiguous'　series；　since　when　the　higher　term　is　excluded；　that



term　of　the　remainder　which　is　'contiguous'　to　it　will　be　primary；　and



so　on。　Our　procedure　makes　it　clear　that　no　elements　in　the



definable　form　have　been　omitted：　we　have　taken　the　differentia　that



comes　first　in　the　order　of　division；　pointing　out　that　animal；　e。g。



is　divisible　exhaustively　into　A　and　B；　and　that　the　subject　accepts



one　of　the　two　as　its　predicate。　Next　we　have　taken　the　differentia　of



the　whole　thus　reached；　and　shown　that　the　whole　we　finally　reach　is



not　further　divisible…i。e。　that　as　soon　as　we　have　taken　the　last



differentia　to　form　the　concrete　totality；　this　totality　admits　of



no　division　into　species。　For　it　is　clear　that　there　is　no　superfluous



addition；　since　all　these　terms　we　have　selected　are　elements　in　the



definable　form；　and　nothing　lacking；　since　any　omission　would　have



to　be　a　genus　or　a　differentia。　Now　the　primary　term　is　a　genus；　and



this　term　taken　in　conjunction　with　its　differentiae　is　a　genus：



moreover　the　differentiae　are　all　included；　because　there　is　now　no



further　differentia；　if　there　were；　the　final　concrete　would　admit



of　division　into　species；　which；　we　said；　is　not　the　case。



　　To　resume　our　account　of　the　right　method　of　investigation：　We



must　start　by　observing　a　set　of　similar…i。e。　specifically



identical…individuals；　and　consider　what　element　they　have　in



common。　We　must　then　apply　the　same　process　to　another　set　of



individuals　which　belong　to　one　species　and　are　generically　but　not



specifically　identical　with　the　former　set。　When　we　have　established



what　the　common　element　is　in　all　members　of　this　second　species；



and　likewise　in　members　of　further　species；　we　should　again　consider



whether　the　results　established　possess　any　identity；　and　persevere



until　we　reach　a　single　formula；　since　this　will　be　the　definition



of　the　thing。　But　if　we　reach　not　one　formula　but　two　or　more；



evidently　the　definiendum　cannot　be　one　thing　but　must　be　more　than



one。　I　may　illustrate　my　meaning　as　follows。　If　we　were　inquiring　what



the　essential　nature　of　pride　is；　we　should　examine　instances　of　proud



men　we　know　of　to　see　what；　as　such；　they　have　in　common；　e。g。　if



Alcibiades　was　proud；　or　Achilles　and　Ajax　were　proud；　we　should



find　on　inquiring　what　they　all　had　in　common；　that　it　was　intolerance



of　insult；　it　was　this　which　drove　Alcibiades　to　war；　Achilles



wrath；　and　Ajax　to　suicide。　We　should　next　examine　other　cases；



Lysander；　for　example；　or　Socrates；　and