darwin and modern science-第112章

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an　any　other　animal。。。The　power　of　being　educated　'educability'　as　we　may　term　itis　what　man　possesses　in　excess　as　compared　with　the　apes。　　I　think　we　are　justified　in　forming　the　hypothesis　that　it　is　this　'educability'　which　is　the　correlative　of　the　increased　size　of　the　cerebrum。〃　　There　has　been　natural　selection　of　the　more　educable　animals；　for　〃the　character　which　we　describe　as　'educability'　can　be　transmitted；　it　is　a　congenital　character。　　But　the　RESULTS　of　education　can　NOT　be　transmitted。　　In　each　generation　they　have　to　be　acquired　afresh；　and　with　increased　'educability'　they　are　more　readily　acquired　and　a　larger　variety　of　them。。。The　fact　is　that　there　is　no　community　between　the　mechanisms　of　instinct　and　the　mechanisms　of　intelligence；　and　that　the　latter　are　later　in　the　history　of　the　evolution　of　the　brain　than　the　former　and　can　only　develop　in　proportion　as　the　former　become　feeble　and　defective。〃　　（〃Nature〃；　Vol。　LXI。　pages　624；　625　（1900）。）

In　this　statement　we　have　a　good　example　of　the　further　development　of　views　which　Darwin　foreshadowed　but　did　not　thoroughly　work　out。　　It　states　the　biological　case　clearly　and　tersely。　　Plasticity　of　behaviour　in　special　accommodation　to　special　circumstances　is　of　survival　value；　it　depends　upon　acquired　characters；　it　is　correlated　with　increase　in　size　and　complexity　of　the　cerebrum；　under　natural　selection　therefore　the　larger　and　more　complex　cerebrum　as　the　organ　of　plastic　behaviour　has　been　the　outcome　of　natural　selection。　　We　have　thus　the　biological　foundations　for　a　further　development　of　genetic　psychology。

There　are　diversities　of　opinion；　as　Darwin　showed；　with　regard　to　the　range　of　instinct　in　man　and　the　higher　animals　as　contrasted　with　lower　types。　　Darwin　himself　said　（〃Descent　of　Man〃；　Vol。　I。　page　100。）　that　〃Man；　perhaps；　has　somewhat　fewer　instincts　than　those　possessed　by　the　animals　which　come　next　to　him　in　the　series。〃　　On　the　other　hand；　Prof。　Wm。　James　says　（〃Principles　of　Psychology；〃　Vol。　II。　page　289。）　that　man　is　probably　the　animal　with　most　instincts。　　The　true　position　is　that　man　and　the　higher　animals　have　fewer　complete　and　self…sufficing　instincts　than　those　which　stand　lower　in　the　scale　of　mental　evolution；　but　that　they　have　an　equally　large　or　perhaps　larger　mass　of　instinctive　raw　material　which　may　furnish　the　stuff　to　be　elaborated　by　intelligent　processes。　　There　is；　perhaps；　a　greater　abundance　of　the　primary　tissue　of　experience　to　be　refashioned　and　integrated　by　secondary　modification；　there　is　probably　the　same　differentiation　in　relation　to　the　determining　biological　ends；　but　there　is　at　the　outset　less　differentiation　of　the　particular　and　specific　modes　of　behaviour。　　The　specialised　instinctive　performances　and　their　concomitant　experience…complexes　are　at　the　outset　more　indefinite。　　Only　through　acquired　connections；　correlated　with　experience；　do　they　become　definitely　organised。

The　full　working…out　of　the　delicate　and　subtle　relationship　of　instinct　and　educabilitythat　is；　of　the　hereditary　and　the　acquired　factors　in　the　mental　lifeis　the　task　which　lies　before　genetic　and　comparative　psychology。　　They　interact　throughout　the　whole　of　life；　and　their　interactions　are　very　complex。　　No　one　can　read　the　chapters　of　〃The　Descent　of　Man〃　which　Darwin　devotes　to　a　consideration　of　the　mental　characters　of　man　and　animals　without　noticing；　on　the　one　hand；　how　sedulous　he　is　in　his　search　for　hereditary　foundations；　and；　on　the　other　hand；　how　fully　he　realises　the　importance　of　acquired　habits　of　mind。　　The　fact　that　educability　itself　has　innate　tendenciesis　in　fact　a　partially　differentiated　educabilityrenders　the　unravelling　of　the　factors　of　mental　progress　all　the　more　difficult。

In　his　comparison　of　the　mental　powers　of　men　and　animals　it　was　essential　that　Darwin　should　lay　stress　on　points　of　similarity　rather　than　on　points　of　difference。　　Seeking　to　establish　a　doctrine　of　evolution；　with　its　basal　concept　of　continuity　of　process　and　community　of　character；　he　was　bound　to　render　clear　and　to　emphasise　the　contention　that　the　difference　in　mind　between　man　and　the　higher　animals；　great　as　it　is；　is　one　of　degree　and　not　of　kind。　　To　this　end　Darwin　not　only　recorded　a　large　number　of　valuable　observations　of　his　own；　and　collected　a　considerable　body　of　information　from　reliable　sources；　he　presented　the　whole　subject　in　a　new　light　and　showed　that　a　natural　history　of　mind　might　be　written　and　that　this　method　of　study　offered　a　wide　and　rich　field　for　investigation。　　Of　course　those　who　regarded　the　study　of　mind　only　as　a　branch　of　metaphysics　smiled　at　the　philosophical　ineptitude　of　the　mere　man　of　science。　　But　the　investigation；　on　natural　history　lines；　has　been　prosecuted　with　a　large　measure　of　success。　　Much　indeed　still　remains　to　be　done；　for　special　training　is　required；　and　the　workers　are　still　few。　　Promise　for　the　future　is　however　afforded　by　the　fact　that　investigation　is　prosecuted　on　experimental　lines　and　that　something　like　organised　methods　of　research　are　taking　form。　　There　is　now　but　little　reliance　on　casual　observations　recorded　by　those　who　have　not　undergone　the　necessary　discipline　in　these　methods。　　There　is　also　some　change　of　emphasis　in　formulating　conclusions。　　Now　that　the　general　evolutionary　thesis　is　fully　and　freely　accepted　by　those　who　carry　on　such　researches；　more　stress　is　laid　on　the　differentiation　of　the　stages　of　evolutionary　advance　than　on　the　fact　of　their　underlying　community　of　nature。　　The　conceptual　intelligence　which　is　especially　characteristic　of　the　higher　mental　procedure　of　man　is　more　firmly　distinguished　from　the　perceptual　intelligence　which　he　shares　with　the　lower　animalsdistinguished　now　as　a　higher　product　of　evolution；　no　longer　as　differing　in　origin　or　different　in　kind。　　Some　progress　has　been　made；　on　the　one　hand　in　rendering　an　account　of　intelligent　profiting　by　experience　under　the　guidance　of　pleasure　and　pain　in　the　perceptual　field；　on　lines　predetermined　by　instinctive　differentiation　for　biological　ends；　and　on　the　other　hand　in　elucidating　the　method　of　conceptual　thought　employed；　for　example；　by　the　investigator　himself　in　interpreting　the　perceptual　experience　of　the　lower　animals。

Thus　there　is　a　growing　tendency　to　realise　more　fully　that　there　are　two　orders　of　educabilityfirst　an　educability　of　the　perceptual　intelligence　based　on　the　biological　foundation　of　instinct；　and　secondly　an　educability　of　the　conceptual　intelligence　which　refashions　and　rearranges　the　data　afforded　by　previous　inheritance　and　acquisition。　　It　is　in　relation　to　this　second　and　higher　order　of　educability　that　the　cerebrum　of　man　shows　so　large　an　increase　of　mass　and　a　yet　larger　increase　of　effective　surface　through　its　rich　convolutions。　　It　is　through　educability　of　this　order　that　the　human　child　is　brought　intellectually　and　affectively　into　touch　with　the　ideal　constructions　by　means　of　which　man　has　endeavoured；　with　more　or　less　success；　to　reach　an　interpretation　of　nature；　and　to　guide　the　course　of　the　further　evolution　of　his　raceideal　constructions　which　form　part　of　man's　environment。

It　formed　no　part　of　Darwin's　purpose　to　consider；　save　in　broad　outline；　the　methods；　or　to　discuss　in　any　fulness　of　detail　the　results　of　the　process　by　which　a　differentiation　of　the　mental　faculties　of　man　from　those　of　the　lower　animals　has　been　brought　abouta　differentiation　the　existence　of　which　he　again　and　again　acknowledges。　　His　purpose　was　rather　to　show　that；　notwithstanding　this　differentiation；　there　is　basal　community　in　kind。　　This　must　be　remembered　in　considering　his　treatment　of　the　biological　foundations　on　which　man's　systems　of　ethics　are　built。　　He　definitely　stated　that　he　approached　the　subject　〃exclusively　from　the　side　of　natural　history。〃　　（〃Descent　of　Man〃；　Vol。　I。　page　149。）　　His　general　conclusion　is　that　the　moral　sense　is　fundamentally　identical　with　the　social　instincts；　which　have　been　developed　for　the　good　of　the　community；　and　he　suggests　that　the　concept　which　thus　enables　us　to　interpret　the　biological　ground…plan　of　morals　also　enables　us　to　frame　a　rational　ideal　of　the　moral　end。　　〃As　the　social　instincts；〃　he　says　（Ibid。　page　185。）；　〃both　of　man　and　the　lower　animals　have　no　doubt　been　developed　by　nearly　the　same　steps；　it　would　be　advisable；　if　found　practicable；　to　use　the　same　definition　in　both　cases；　and　to　take　as　the　standard　of　morality；　the　general　good　or　welfare　of　the　community；　rather　than　the　general　happiness。〃　　But　the　kind　of　community　for　the　good　of　which　the　social　instincts　of　animals　and　primitive　men　were　biologically　developed　may　be　different　from　that　which　is　the　product　of　civilisation；　as　Darwin　no　doubt　realised。　　Darwin's　contention　was　that　conscience　is　a　social　instinct　and　has　been　evolved　because　it　is　useful　to　the　tribe　in　the　struggle　for　existence　against　other　tribes。　　On　the　other　hand；　J。S。　Mill　urged　that　the　moral　feelings　are　not　innate　but　acquired；　and　Bain　held　the　same　view；　believing　that　the　moral　sense　is　acquired　by　each　individual　during　his　life…time。　　Darwin；　who　notes　（Ibid。　page　150　（footnote）。）　their　opinion　with　his　usual　candour；　adds　that　〃on　the　general　theory　of　evolution　this　is　at　least　extremely　improbable。　　It　is　impossible　to　enter　into　the　question　here：　　much　turns　on　the　exact　connotation　of　the　terms　〃conscience〃　and　〃moral　sense；〃　and　on　the　meaning　we　attach　to　the　statement　that　the　moral　sense　is　fundamentally　identical　with　the　social　instincts。

Presumably　the　majority　of　those　who　approach　the　subjects　discussed　in　the　third；　fourth　and　fifth　chapters　of　〃The　Descent　of　Man〃　in　the　full　conviction　that　mental　phenomena；　not　less　than　organic　phenomena；　have　a　natural　genesis；　would；　without　hesitation；　admit　that　the　intellectual　and　moral　systems　of　civilised　man　are　ideal　constructions；　the　products　of　conceptual　thought；　and　that　as　such　they　are；　in　their　developed　form；　acquired。　　The　moral　sentiments　are　the　emotional　analogues　of　highly　developed　concepts。　　This　does　not　however　imply　that　they　are　outside　the　range　of　natural　history　treatment。　　Even　though　it　may　be　desirable　to　differentiate　the　moral　conduct　of　men　from　the　social　behaviour　of　animals　（to　which　some　such　term　as　〃pre…moral〃　or　〃quasi…moral〃　may　be　applied）；　still　the　fact　remains　that；　as　Darwin　showed；　there　is　abundant　evidence　of　the　occurrence　of　such　social　behavioursocial　behaviour　which；　even　granted　that　it　is　in　large　part　intelligently　acquired；　and　is　itself　so　far　a　product　of　educability；　is　of　survival　value。　　It　makes　for　that　integration　without　which　no　social　group　could　hold　together　and　escape　elimination。　　Furthermore；　even　if　we　grant　that　such　behaviour　is　intelligently　acquired；　that　is　to　say　arises　through　the　modification　of　hereditary　instincts　and　emotions；　the　fact　remains　that　only　through　these　instinctive　and　emotional　data　is　afforded　the　primary　tissue　of　the　experience　which　is　susceptible　of　such　modification。

Darwin　sought　to　show；　and　succeeded　in　showing；　that　for　the　intellectual　and　moral　life　there　are　instinctive　foundations　which　a　biological　treatment　alone　can　disclose。　　It