criminal psychology- 第36部分

In　our　own　cases　we　need　no　examples；　for　I　know　of　no　inference　which　was　not　made　in　the　following　fashion：　‘‘The　situation　was　so　in　a　hundred　cases；　it　must　be　so　in　this　case。''　We　rarely　ask　whether　we　know　enough　examples；　whether　they　were　the　correct　ones；　and　whether　they　were　exhaustive。　It　will　be　no　mistake　to　assert　that　we　lawyers　do　this　more　or　less　consciously　on　the　supposition　that　we　have　an　immense　collection　of　suggestive　a　priori　inferences　which　the　human　understanding　has　brought　together　for　thousands　of　years；　and　hence　believe　them　to　be　indubitably　certain。　If　we　recognize　that　all　these　presuppositions　are　compounds　of　experience；　and　that　every　experience　may　finally　show　itself　to　be　deceptive　and　false；　if　we　recognize　how　the　actual　progress　of　human　knowledge　consists　in　the　addition　of　one　hundred　new　experiences　to　a　thousand　old　ones；　and　if　we　recognize　that　many　of　the　new　ones　contradict　the　old　ones：　if　we　recognize　the　consequence　that　there　is　no　reason　for　the　mathematical　deduction　from　the　first　to　the　hundred…and…first　case；　we　shall　make　fewer　mistakes　and　do　less　harm。　In　this　regard；　Hume＇1＇　is　very　illuminative。

According　to　Masaryk；＇2＇　the　fundamental　doctrine　of　Humian　skepticism　is　as　follows：　‘‘If　I　have　had　one　and　the　same　experience　ever　so　often；　i。　e。；　if　I　have　seen　the　sun　go　up　100　times；　I　expect　to　see　it　go　up　the　101st　time　the　next　day；　but　I　have　no　guarantee；　no　certainty；　no　evidence　for　this　belief。　Experience　looks　only　to　the　past；　not　to　the　future。　How　can　I　then　discover　the　101st　sunrise　in　the　first　100　sunrises？　Experience　reveals　in　me　the　habit　to　expect　similar　effects　from　similar　circumstances；　but　the　intellect　has　no　share　in　this　expectation。''

All　the　sciences　based　on　experience　are　uncertain　and　without　logical　foundation；　even　though　their　results；　as　a　whole　and　in　the　mass；　are　predictable。　Only　mathematics　offers　certainty　and　evidence。　Therefore；　according　to　Hume；　sciences　based　on　experience　are　unsafe　because　the　recognition　of　causal　connection　depends　on　the　facts　of　experience　and　we　can　attain　to　certain　knowledge　of　the　facts　of　experience　only　on　the　ground　of　the　evident　relation　of　cause　and　effect。

This　view　was　first　opposed　by　Reid；　who　tried　to　demonstrate　that　we　have　a　clear　notion　of　necessary　connection。　He　grants　that　this　notion　is　not　directly　attained　either　from　external　or　internal　experience；　but　asserts　its　clearness　and　certainty　in　spite

＇1＇　Cf。　Hume's　Treatise　of　Human　Nature。

＇2＇　Masaryk：　David　Hume's　Skepsis。　Vienna　1884。

　of　that　fact。　Our　mind　has　the　power　to　make　its　own　concepts　and　one　such　concept　is　that　of　necessary　connection。　Kant　goes　further　and　says　that　Hume　failed　to　recognize　the　full　consequences　of　his　own　analysis；　for　the　notion　of　causality　is　not　the　only　one　which　the　understanding　uses　to　represent　a　priori　the　connection　of　objects。　And　hence；　Kant　defines　psychologically　and　logically　a　whole　system　of　similar　concepts。　His　‘‘Critique　of　Pure　Reason''　is　intended　historically　and　logically　as　the　refutation　of　Hume's　skepticism。　It　aims　to　show　that　not　only　metaphysics　and　natural　science　have　for　their　basis　‘‘synthetic　judgments　a　priori；''　but　that　mathematics　also　rests　on　the　same　foundation。

Be　that　as　it　may；　our　task　is　to　discover　the　application　of　Hume's　skepticism　to　our　own　problems　in　some　clear　example。　Let　us　suppose　that　there　are　a　dozen　instances　of　people　who　grew　to　be　from　120　to　140　years　old。　These　instances　occur　among　countless　millions　of　cases　in　which　such　an　age　was　not　reached。　If　this　small　proportion　is　recognized；　it　justifies　the　postulate　that　nobody　on　earth　may　attain　to　150　years。　But　now　it　is　known　that　the　Englishman　Thomas　Parr　got　to　be　152　years　old；　and　his　countryman　Jenkins　was　shown；　according　to　the　indubitable　proofs　of　the　Royal　Society；　to　be　157　years　old　at　least　（according　to　his　portrait　in　a　copper　etching　he　was　169　years　old）。　Yet　as　this　is　the　most　that　has　been　scientifically　proved　I　am　justified　in　saying　that　nobody　can　grow　to　be　200　years　old。　Nevertheless　because　there　are　people　who　have　attained　the　age　of　180　to　190　years；　nobody　would　care　to　assert　that　it　is　absolutely　impossible　to　grow　so　old。　The　names　and　histories　of　these　people　are　recorded　and　their　existence　removes　the　great　reason　against　this　possibility。

We　have　to　deal；　then；　only　with　greater　or　lesser　possibilities　and　agree　with　the　Humian　idea　that　under　similar　conditions　frequency　of　occurrence　implies　repetition　in　the　next　instance。　Contrary　evidence　may　be　derived　from　several　so…called　phenomena　of　alternation。　E。　g。；　it　is　a　well　known　fact　that　a　number　in　the　so…called　Little　Lottery；　which　has　not　been　drawn　for　a　long　time；　is　sure　finally　to　be　drawn。　If　among　90　numbers　the　number　27　has　not　turned　up　for　a　long　time　its　appearance　becomes　more　probable　with　every　successive　drawing。　All　the　so…called　mathematical　combinations　of　players　depend　on　this　experience；　which；　generalized；　might　be　held　to　read：　the　oftener　any　event　occurs　（as　the　failure　of　the　number　27　to　be　drawn）　the　less　is　the　proba…　　bility　of　its　recurrence　（i。　e。；　it　becomes　more　probable　that　27　will　be　drawn）and　this　seems　the　contrary　of　Hume's　proposition。

It　may　at　first　be　said　that　the　example　ought　to　be　put　in　a　different　form；　i。　e。；　as　follows：　If　I　know　that　a　bag　contains　marbles；　the　color　of　which　I　do　not　know；　and　if　I　draw　them　one　by　one　and　always　find　the　marble　I　have　drawn　to　be　white；　the　probability　that　the　bag　contains　only　white　ones　grows　with　every　new　drawing　that　brings　a　white　marble　to　light。　If　the　bag　contains　100　marbles　and　99　have　been　drawn　out；　nobody　would　suppose　that　the　last　one　would　be　redfor　the　repetition　of　any　event　increases　the　probability　of　its　occurrence。

This　formulation　proves　nothing；　inasmuch　as　a　different　example　does　not　contradict　the　one　it　is　intended　to　substitute。　The　explanation　is　rather　as　follows：　In　the　first　case　there　is　involved　the　norm　of　equal　possibilities；　and　if　we　apply　the　Humian　principle　of　increase　of　probability　through　repetition；　we　find　it　effective　in　explaining　the　example。　We　have　known　until　now　always　that　the　numbers　in　the　Little　Lottery　are　drawn　equally；　and　with　approximate　regularity；i。　e。；　none　of　the　single　numbers　is　drawn　for　a　disproportionately　long　time。　And　as　this　fact　is　invariable；　we　may　suppose　that　every　individual　number　would　appear　with　comparative　regularity。　But　this　explanation　is　in　accord　with　Hume's　doctrine。

The　doctrine　clarifies　even　astonishing　statistical　miracles。　We　know；　e。　g。；　that　every　year　there　come　together　in　a　certain　region　a　large　number　of　suicides；　fractures　of　arms　and　legs；　assaults；　unaddressed　letters；　etc。　When；　now；　we　discover　that　the　number　of　suicides　in　a　certain　semester　is　significantly　less　than　the　number　in　the　same　semester　of　another　year；　we　will　postulate　that　in　the　next　half…year　a　comparatively　larger　number　of　suicides　will　take　place　so　that　the　number　for　the　whole　year　will　become　approximately　equal。　Suppose　we　say：　‘‘There　were　in　the　months　of　January；　February；　March；　April；　May　and　June　an　average　of　x　cases。　Because　we　have　observed　the　average　to　happen　six　times；　we　conclude　that　it　will　not　happen　in　the　other　months　but　that　instead；　x＋y　cases　will　occur　in　those　months；　since　otherwise　the　average　annual　count　will　not　be　attained。''　This　would　be　a　mistaken　abstraction　of　the　principle　of　equal　distribution　from　the　general　Humian　law；　for　the　Humian　law　applied　to　this　case　indicates：　‘‘For　a　long　series　of　years　we　have　observed　that　in　　this　region　there　occur　annually　so　and　so　many　suicides；　we　conclude　therefore　that　in　this　year　also　there　will　occur　a　similar　number　of　suicides。''

The　principle　of　equal　distribution　presents　itself　therefore　as　a　subordinate　rule　which　must　not　be　separated　from　the　principal　law。　It　is；　indeed；　valid　for　the　simplest　events。　When　I　resolve　to　walk　in　x　street；　which　I　know　well；　and　when　I　recall　whether　to…day　is　Sunday　or　a　week　day；　what　time　it　is　and　what　the　weather　is　like；　I　know　quite　accurately　how　the　street　will　look　with　regard　to　the　people　that　may　be　met　there；　although　a　large　number　of　these　people　have　chosen　the　time　accidentally　and　might　as　well　have　passed　through　another　street。　If；　for　once；　there　were　more　people　in　the　street；　I　should　immediately　ask　myself　what　unusual　event　had　taken　place。

One　of　my　cousins　who　had　a　good　deal　of　free　time　to　dispose　of；　spent　it　for　several　months；　with　the　assistance　of　his　comrade；　in　counting　the　number　of　horses　that　passed　daily；　in　the　course　of　two　hours；　by　a　caf