the critique of practical reason- 第1部分

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　1788
　　　　　　　　　　　　　　　　　　　　　　　　THE　CRITIQUE　OF　PRACTICAL　REASON
　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　by　Immanuel　Kant
　　　　　　　　　　　　　　　　　　　　　translated　by　Thomas　Kingsmill　Abbott



　　　　　　　　　　　　　　　　　　　　　　　　　PREFACE

　　This　work　is　called　the　Critique　of　Practical　Reason；　not　of　the　pure　practical　reason；　although　its　parallelism　with　the　speculative　critique　would　seem　to　require　the　latter　term。　The　reason　of　this　appears　sufficiently　from　the　treatise　itself。　Its　business　is　to　show　that　there　is　pure　practical　reason；　and　for　this　purpose　it　criticizes　the　entire　practical　faculty　of　reason。　If　it　succeeds　in　this；　it　has　no　need　to　criticize　the　pure　faculty　itself　in　order　to　see　whether　reason　in　making　such　a　claim　does　not　presumptuously　overstep　itself　（as　is　the　case　with　the　speculative　reason）。　For　if；　as　pure　reason；　it　is　actually　practical；　it　proves　its　own　reality　and　that　of　its　concepts　by　fact；　and　all　disputation　against　the　possibility　of　its　being　real　is　futile。　　　With　this　faculty；　transcendental　freedom　is　also　established；　freedom；　namely；　in　that　absolute　sense　in　which　speculative　reason　required　it　in　its　use　of　the　concept　of　causality　in　order　to　escape　the　antinomy　into　which　it　inevitably　falls；　when　in　the　chain　of　cause　and　effect　it　tries　to　think　the　unconditioned。　Speculative　reason　could　only　exhibit　this　concept　（of　freedom）　problematically　as　not　impossible　to　thought；　without　assuring　it　any　objective　reality；　and　merely　lest　the　supposed　impossibility　of　what　it　must　at　least　allow　to　be　thinkable　should　endanger　its　very　being　and　plunge　it　into　an　abyss　of　scepticism。　　　Inasmuch　as　the　reality　of　the　concept　of　freedom　is　proved　by　an　apodeictic　law　of　practical　reason；　it　is　the　keystone　of　the　whole　system　of　pure　reason；　even　the　speculative；　and　all　other　concepts　（those　of　God　and　immortality）　which；　as　being　mere　ideas；　remain　in　it　unsupported；　now　attach　themselves　to　this　concept；　and　by　it　obtain　consistence　and　objective　reality；　that　is　to　say；　their　possibility　is　proved　by　the　fact　that　freedom　actually　exists；　for　this　idea　is　revealed　by　the　moral　law。　　　Freedom；　however；　is　the　only　one　of　all　the　ideas　of　the　speculative　reason　of　which　we　know　the　possibility　a　priori　（without；　however；　understanding　it）；　because　it　is　the　condition　of　the　moral　law　which　we　know。*　The　ideas　of　God　and　immortality；　however；　are　not　conditions　of　the　moral　law；　but　only　conditions　of　the　necessary　object　of　a　will　determined　by　this　law；　that　is　to　say；　conditions　of　the　practical　use　of　our　pure　reason。　Hence；　with　respect　to　these　ideas；　we　cannot　affirm　that　we　know　and　understand；　I　will　not　say　the　actuality；　but　even　the　possibility　of　them。　However　they　are　the　conditions　of　the　application　of　the　morally　determined　will　to　its　object；　which　is　given　to　it　a　priori；　viz。；　the　summum　bonum。　Consequently　in　this　practical　point　of　view　their　possibility　must　be　assumed；　although　we　cannot　theoretically　know　and　understand　it。　To　justify　this　assumption　it　is　sufficient；　in　a　practical　point　of　view；　that　they　contain　no　intrinsic　impossibility　（contradiction）。　Here　we　have　what；　as　far　as　speculative　reason　is　concerned；　is　a　merely　subjective　principle　of　assent；　which；　however；　is　objectively　valid　for　a　reason　equally　pure　but　practical；　and　this　principle；　by　means　of　the　concept　of　freedom；　assures　objective　reality　and　authority　to　the　ideas　of　God　and　immortality。　Nay；　there　is　a　subjective　necessity　（a　need　of　pure　reason）　to　assume　them。　Nevertheless　the　theoretical　knowledge　of　reason　is　not　hereby　enlarged；　but　only　the　possibility　is　given；　which　heretofore　was　merely　a　problem　and　now　becomes　assertion；　and　thus　the　practical　use　of　reason　is　connected　with　the　elements　of　theoretical　reason。　And　this　need　is　not　a　merely　hypothetical　one　for　the　arbitrary　purposes　of　speculation；　that　we　must　assume　something　if　we　wish　in　speculation　to　carry　reason　to　its　utmost　limits；　but　it　is　a　need　which　has　the　force　of　law　to　assume　something　without　which　that　cannot　be　which　we　must　inevitably　set　before　us　as　the　aim　of　our　action。

　　*Lest　any　one　should　imagine　that　he　finds　an　inconsistency　here　when　I　call　freedom　the　condition　of　the　moral　law；　and　hereafter　maintain　in　the　treatise　itself　that　the　moral　law　is　the　condition　under　which　we　can　first　become　conscious　of　freedom；　I　will　merely　remark　that　freedom　is　the　ratio　essendi　of　the　moral　law；　while　the　moral　law　is　the　ratio　cognoscendi　of　freedom。　For　Pad　not　the　moral　law　been　previously　distinctly　thought　in　our　reason；　we　should　never　consider　ourselves　justified　in　assuming　such　a　thing　as　freedom；　although　it　be　not　contradictory。　But　were　there　no　freedom　it　would　be　impossible　to　trace　the　moral　law　in　ourselves　at　all。

　　It　would　certainly　be　more　satisfactory　to　our　speculative　reason　if　it　could　solve　these　problems　for　itself　without　this　circuit　and　preserve　the　solution　for　practical　use　as　a　thing　to　be　referred　to；　but　in　fact　our　faculty　of　speculation　is　not　so　well　provided。　Those　who　boast　of　such　high　knowledge　ought　not　to　keep　it　back；　but　to　exhibit　it　publicly　that　it　may　be　tested　and　appreciated。　They　want　to　prove：　very　good；　let　them　prove；　and　the　critical　philosophy　lays　its　arms　at　their　feet　as　the　victors。　Quid　statis？　Nolint。　Atqui　licet　esse　beatis。　As　they　then　do　not　in　fact　choose　to　do　so；　probably　because　they　cannot；　we　must　take　up　these　arms　again　in　order　to　seek　in　the　mortal　use　of　reason；　and　to　base　on　this；　the　notions　of　God；　freedom；　and　immortality；　the　possibility　of　which　speculation　cannot　adequately　prove。　　　Here　first　is　explained　the　enigma　of　the　critical　philosophy；　viz。：　how　we　deny　objective　reality　to　the　supersensible　use　of　the　categories　in　speculation　and　yet　admit　this　reality　with　respect　to　the　objects　of　pure　practical　reason。　This　must　at　first　seem　inconsistent　as　long　as　this　practical　use　is　only　nominally　known。　But　when；　by　a　thorough　analysis　of　it；　one　becomes　aware　that　the　reality　spoken　of　does　not　imply　any　theoretical　determination　of　the　categories　and　extension　of　our　knowledge　to　the　supersensible；　but　that　what　is　meant　is　that　in　this　respect　an　object　belongs　to　them；　because　either　they　are　contained　in　the　necessary　determination　of　the　will　a　priori；　or　are　inseparably　connected　with　its　object；　then　this　inconsistency　disappears；　because　the　use　we　make　of　these　concepts　is　different　from　what　speculative　reason　requires。　On　the　other　hand；　there　now　appears　an　unexpected　and　very　satisfactory　proof　of　the　consistency　of　the　speculative　critical　philosophy。　For　whereas　it　insisted　that　the　objects　of　experience　as　such；　including　our　own　subject；　have　only　the　value　of　phenomena；　while　at　the　same　time　things　in　themselves　must　be　supposed　as　their　basis；　so　that　not　everything　supersensible　was　to　be　regarded　as　a　fiction　and　its　concept　as　empty；　so　now　practical　reason　itself；　without　any　concert　with　the　speculative；　assures　reality　to　a　supersensible　object　of　the　category　of　causality；　viz。；　freedom；　although　（as　becomes　a　practical　concept）　only　for　practical　use；　and　this　establishes　on　the　evidence　of　a　fact　that　which　in　the　former　case　could　only　be　conceived。　By　this　the　strange　but　certain　doctrine　of　the　speculative　critical　philosophy；　that　the　thinking　subject　is　to　itself　in　internal　intuition　only　a　phenomenon；　obtains　in　the　critical　examination　of　the　practical　reason　its　full　confirmation；　and　that　so　thoroughly　that　we　should　be　compelled　to　adopt　this　doctrine；　even　if　the　former　had　never　proved　it　at　all。*

　　*The　union　of　causality　as　freedom　with　causality　as　rational　mechanism；　the　former　established　by　the　moral　law；　the　latter　by　the　law　of　nature　in　the　same　subject；　namely；　man；　is　impossible；　unless　we　conceive　him　with　reference　to　the　former　as　a　being　in　himself；　and　with　reference　to　the　latter　as　a　phenomenon…　the　former　in　pure　consciousness；　the　latter　in　empirical　consciousness。　Otherwise　reason　inevitably　contradicts　itself。

　　By　this　also　I　can　understand　why　the　most　considerable　objections　which　I　have　as　yet　met　with　against　the　Critique　turn　about　these　two　points；　namely；　on　the　one　side；　the　objective　reality　of　the　categories　as　applied　to　noumena；　which　is　in　the　theoretical　department　of　knowledge　denied；　in　the　practical　affirmed；　and　on　the　other　side；　the　paradoxical　demand　to　regard　oneself　qua　subject　of　freedom　as　a　noumenon；　and　at　the　same　time　from　the　point　of　view　of　physical　nature　as　a　phenomenon　in　one's　own　empirical　consciousness；　for　as　long　as　one　has　formed　no　definite　notions　of　morality　and　freedom；　one　could　not　conjecture　on　the　one　side　what　was　intended　to　be　the　noumenon；　the　basis　of　the　alleged　phenomenon；　and　on　the　other　side　it　seemed　doubtful　whether　it　was　at　all　possible　to　form　any　notion　of　it；　seeing　that　we　had　previously　assigned　all　the　notions　of　the　pure　understanding　in　its　theoretical　use　exclusively　to　phenomena。　Nothing　but　a　detailed　criticism　of　the　practical　reason　can　remove　all　this　misapprehension　and　set　in　a　clear　light　the　consistency　which　constitutes　its　greatest　merit