prior analytics-第24章

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will　disappear　if　B　is　eliminated。　Similarly　when　the　syllogisms　are



negative。



　　It　is　clear　then　that　when　the　impossibility　is　not　related　to　the



original　terms；　the　false　conclusion　does　not　result　on　account　of　the



assumption。　Or　perhaps　even　so　it　may　sometimes　be　independent。　For　if



it　were　laid　down　that　A　belongs　not　to　B　but　to　K；　and　that　K　belongs



to　C　and　C　to　D；　the　impossible　conclusion　would　still　stand。



Similarly　if　one　takes　the　terms　in　an　ascending　series。



Consequently　since　the　impossibility　results　whether　the　first



assumption　is　suppressed　or　not；　it　would　appear　to　be　independent



of　that　assumption。　Or　perhaps　we　ought　not　to　understand　the



statement　that　the　false　conclusion　results　independently　of　the



assumption；　in　the　sense　that　if　something　else　were　supposed　the



impossibility　would　result；　but　rather　we　mean　that　when　the　first



assumption　is　eliminated；　the　same　impossibility　results　through　the



remaining　premisses；　since　it　is　not　perhaps　absurd　that　the　same



false　result　should　follow　from　several　hypotheses；　e。g。　that



parallels　meet；　both　on　the　assumption　that　the　interior　angle　is



greater　than　the　exterior　and　on　the　assumption　that　a　triangle



contains　more　than　two　right　angles。







　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　18







　　A　false　argument　depends　on　the　first　false　statement　in　it。　Every



syllogism　is　made　out　of　two　or　more　premisses。　If　then　the　false



conclusion　is　drawn　from　two　premisses；　one　or　both　of　them　must　be



false：　for　（as　we　proved）　a　false　syllogism　cannot　be　drawn　from　two



premisses。　But　if　the　premisses　are　more　than　two；　e。g。　if　C　is



established　through　A　and　B；　and　these　through　D；　E；　F；　and　G；　one



of　these　higher　propositions　must　be　false；　and　on　this　the　argument



depends：　for　A　and　B　are　inferred　by　means　of　D；　E；　F；　and　G。



Therefore　the　conclusion　and　the　error　results　from　one　of　them。







　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　19







　　In　order　to　avoid　having　a　syllogism　drawn　against　us　we　must　take



care；　whenever　an　opponent　asks　us　to　admit　the　reason　without　the



conclusions；　not　to　grant　him　the　same　term　twice　over　in　his



premisses；　since　we　know　that　a　syllogism　cannot　be　drawn　without　a



middle　term；　and　that　term　which　is　stated　more　than　once　is　the



middle。　How　we　ought　to　watch　the　middle　in　reference　to　each



conclusion；　is　evident　from　our　knowing　what　kind　of　thesis　is



proved　in　each　figure。　This　will　not　escape　us　since　we　know　how　we



are　maintaining　the　argument。



　　That　which　we　urge　men　to　beware　of　in　their　admissions；　they



ought　in　attack　to　try　to　conceal。　This　will　be　possible　first；　if；



instead　of　drawing　the　conclusions　of　preliminary　syllogisms；　they



take　the　necessary　premisses　and　leave　the　conclusions　in　the　dark；



secondly　if　instead　of　inviting　assent　to　propositions　which　are



closely　connected　they　take　as　far　as　possible　those　that　are　not



connected　by　middle　terms。　For　example　suppose　that　A　is　to　be



inferred　to　be　true　of　F；　B；　C；　D；　and　E　being　middle　terms。　One　ought



then　to　ask　whether　A　belongs　to　B；　and　next　whether　D　belongs　to　E；



instead　of　asking　whether　B　belongs　to　C；　after　that　he　may　ask



whether　B　belongs　to　C；　and　so　on。　If　the　syllogism　is　drawn　through



one　middle　term；　he　ought　to　begin　with　that：　in　this　way　he　will　most



likely　deceive　his　opponent。







　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　20







　　Since　we　know　when　a　syllogism　can　be　formed　and　how　its　terms



must　be　related；　it　is　clear　when　refutation　will　be　possible　and　when



impossible。　A　refutation　is　possible　whether　everything　is　conceded；



or　the　answers　alternate　（one；　I　mean；　being　affirmative；　the　other



negative）。　For　as　has　been　shown　a　syllogism　is　possible　whether　the



terms　are　related　in　affirmative　propositions　or　one　proposition　is



affirmative；　the　other　negative：　consequently；　if　what　is　laid　down　is



contrary　to　the　conclusion；　a　refutation　must　take　place：　for　a



refutation　is　a　syllogism　which　establishes　the　contradictory。　But



if　nothing　is　conceded；　a　refutation　is　impossible：　for　no　syllogism



is　possible　（as　we　saw）　when　all　the　terms　are　negative：　therefore



no　refutation　is　possible。　For　if　a　refutation　were　possible；　a



syllogism　must　be　possible；　although　if　a　syllogism　is　possible　it



does　not　follow　that　a　refutation　is　possible。　Similarly　refutation　is



not　possible　if　nothing　is　conceded　universally：　since　the　fields　of



refutation　and　syllogism　are　defined　in　the　same　way。







　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　21







　　It　sometimes　happens　that　just　as　we　are　deceived　in　the　arrangement



of　the　terms；　so　error　may　arise　in　our　thought　about　them；　e。g。　if　it



is　possible　that　the　same　predicate　should　belong　to　more　than　one



subject　immediately；　but　although　knowing　the　one；　a　man　may　forget



the　other　and　think　the　opposite　true。　Suppose　that　A　belongs　to　B　and



to　C　in　virtue　of　their　nature；　and　that　B　and　C　belong　to　all　D　in



the　same　way。　If　then　a　man　thinks　that　A　belongs　to　all　B；　and　B　to



D；　but　A　to　no　C；　and　C　to　all　D；　he　will　both　know　and　not　know　the



same　thing　in　respect　of　the　same　thing。　Again　if　a　man　were　to　make　a



mistake　about　the　members　of　a　single　series；　e。g。　suppose　A　belongs



to　B；　B　to　C；　and　C　to　D；　but　some　one　thinks　that　A　belongs　to　all　B；



but　to　no　C：　he　will　both　know　that　A　belongs　to　D；　and　think　that



it　does　not。　Does　he　then　maintain　after　this　simply　that　what　he



knows；　he　does　not　think？　For　he　knows　in　a　way　that　A　belongs　to　C



through　B；　since　the　part　is　included　in　the　whole；　so　that　what　he



knows　in　a　way；　this　he　maintains　he　does　not　think　at　all：　but　that



is　impossible。



　　In　the　former　case；　where　the　middle　term　does　not　belong　to　the



same　series；　it　is　not　possible　to　think　both　the　premisses　with



reference　to　each　of　the　two　middle　terms：　e。g。　that　A　belongs　to



all　B；　but　to　no　C；　and　both　B　and　C　belong　to　all　D。　For　it　turns　out



that　the　first　premiss　of　the　one　syllogism　is　either　wholly　or



partially　contrary　to　the　first　premiss　of　the　other。　For　if　he　thinks



that　A　belongs　to　everything　to　which　B　belongs；　and　he　knows　that　B



belongs　to　D；　then　he　knows　that　A　belongs　to　D。　Consequently　if　again



he　thinks　that　A　belongs　to　nothing　to　which　C　belongs；　he　thinks　that



A　does　not　belong　to　some　of　that　to　which　B　belongs；　but　if　he　thinks



that　A　belongs　to　everything　to　which　B　belongs；　and　again　thinks　that



A　does　not　belong　to　some　of　that　to　which　B　belongs；　these　beliefs



are　wholly　or　partially　contrary。　In　this　way　then　it　is　not



possible　to　think；　but　nothing　prevents　a　man　thinking　one　premiss



of　each　syllogism　of　both　premisses　of　one　of　the　two　syllogisms：　e。g。



A　belongs　to　all　B；　and　B　to　D；　and　again　A　belongs　to　no　C。　An



error　of　this　kind　is　similar　to　the　error　into　which　we　fall



concerning　particulars：　e。g。　if　A　belongs　to　all　B；　and　B　to　all　C；



A　will　belong　to　all　C。　If　then　a　man　knows　that　A　belongs　to



everything　to　which　B　belongs；　he　knows　that　A　belongs　to　C。　But



nothing　prevents　his　being　ignorant　that　C　exists；　e。g。　let　A　stand



for　two　right　angles；　B　for　triangle；　C　for　a　particular　diagram　of



a　triangle。　A　man　might　think　that　C　did　not　exist；　though　he　knew



that　every　triangle　contains　two　right　angles；　consequently　he　will



know　and　not　know　the　same　thing　at　the　same　time。　For　the



expression　'to　know　that　every　triangle　has　its　angles　equal　to　two



right　angles'　is　ambiguous；　meaning　to　have　the　knowledge　either　of



the　universal　or　of　the　particulars。　Thus　then　he　knows　that　C



contains　two　right　angles　with　a　knowledge　of　the　universal；　but　not



with　a　knowledge　of　the　particulars；　consequently　his　knowledge　will



not　be　contrary　to　his　ignorance。　The　argument　in　the　Meno　that



learning　is　recollection　may　be　criticized　in　a　similar　way。　For　it



never　happens　that　a　man　starts　with　a　foreknowledge　of　the



particular；　but　along　with　the　process　of　being　led　to　see　the　general



principle　he　receives　a　knowledge　of　the　particulars；　by　an　act　（as　it



were）　of　recognition。　For　we　know　some　things　directly；　e。g。　that



the　angles　are　equal　to　two　right　angles；　if　we　know　that　the　figure



is　a　triangle。　Similarly　in　all　other　cases。



　　By　a　knowledge　of　the　universal　then　we　see　the　particulars；　but



we　do　not　know　them　by　the　kind　of　knowledge　which　is　proper　to



them；　consequently　it　is　possible　that　we　may　make　mistakes　about



them；　but　not　that　we　should　have　the　knowledge　and　error　that　are



contrary　to　one　another：　rather　we　have　the　knowledge　of　the　universal



but　make　a　mistake　in　apprehending　the　particular。　Similarly　in　the



cases　stated　above。　The　error　in　respect　of　the　middle　term　is　not



contrary　to　the　knowledge　obtained　through　the　syllogism；　nor　is　the



thought　in　respect　of　one　middle　term　contrary　to　that　in　respect　of



the　other。　Nothing　prevents　a　man　who　knows　both　that　A　belongs　to　the



whole　of　B；　and　that　B　again　belongs　to　C；　thinking　that　A　does　not



belong　to　C；　e。g。　knowing　that　every　mule　is　sterile　and　that　this



is　a　mule；　and　thinking　that　this　animal　is　with　foal：　for　he　does　not



know　that　A　belongs　to　C；　unless　he　considers　the　two　propositions



together。　So　it　is　evident　that　if　he　knows　the　one　and　does　not



know　the　other；　he　will　fall　into　error。　And　this　is　the　relation　of



knowledge　of　the　universal　to　knowledge　of　the　particular。　For　we　know



no　sensible　thing；　once　it　has　passed　beyond　the　range　of　our



senses；　even　if　we　happen　to　have　perceived　it；　except　by　means　of　the



universal　and　the　possession　of　the　knowledge　which　is　proper　to　the



particular；　but　without　the　actual　exercise　of　that　knowledge。　For



to　know　is　used　in　three　senses：　it　may　mean　either　to　have



knowledge　of　the　universal　or　to　have　knowledge　proper　to　the　matter



in　hand　or　to　exercise　such　knowledge：　consequently　three　kinds　of



error　also　are　possible。　Nothing　then　prevents　a　man　both　knowing



and　being　mistaken　about　the　same　thing；　provided　that　his　knowledge



and　his　error　are　not　contrary。　And　this　happens　also　to　the　man　whose



knowledge　is　limited　to　each　of　the　premisses　and　who　has　not



previously　considered　the　particular　question。　For　when　he　thinks　that



the　mule　is　with　foal　he　has　not　the　knowledge　in　the　sense　of　its



actual　exercise；　nor　on　the　other　hand　has　his　thought　caused　an　error



contrary　to　his　kn