an enquiry concerning human understanding-第20章

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liberty；　according　to　any　reasonable　sense；　which　can　be　put
on　these　terms；　and　that　the　whole　controversy；　has　hitherto
turned　merely　upon　words。　We　shall　begin　with　examining　the
doctrine　of　necessity。

　　　　　It　is　universally　allowed　that　matter；　in　all　its
operations；　is　actuated　by　a　necessary　force；　and　that　every
natural　effect　is　so　precisely　determined　by　the　energy　of
its　cause　that　no　other　effect；　in　such　particular
circumstances；　could　possibly　have　resulted　from　it。　The
degree　and　direction　of　every　motion　is；　by　the　laws　of
nature；　prescribed　with　such　exactness　that　a　living
creature　may　as　soon　arise　from　the　shock　of　two　bodies　as
motion　in　any　other　degree　or　direction　than　what　is
actually　produced　by　it。　Would　we；　therefore；　form　a　just
and　precise　idea　of　；　we　must　consider　whence
that　idea　arises　when　we　apply　it　to　the　operation　of
bodies。

　　　　　It　seems　evident　that；　if　all　the　scenes　of　nature　were
continually　shifted　in　such　a　manner　that　no　two　events　bore
any　resemblance　to　each　other；　but　every　object　was　entirely
new；　without　any　similitude　to　whatever　had　been　seen
before；　we　should　never；　in　that　case；　have　attained　the
least　idea　of　necessity；　or　of　a　connexion　among　these
objects。　We　might　say；　upon　such　a　supposition；　that　one
object　or　event　has　followed　another；　not　that　one　was
produced　by　the　other。　The　relation　of　cause　and　effect　must
be　utterly　unknown　to　mankind。　Inference　and　reasoning
concerning　the　operations　of　nature　would；　from　that　moment；
be　at　an　end；　and　the　memory　and　senses　remain　the　only
canals；　by　which　the　knowledge　of　any　real　existence　could
possibly　have　access　to　the　mind。　Our　idea；　therefore；　of
necessity　and　causation　arises　entirely　from　the　uniformity
observable　in　the　operations　of　nature；　where　similar
objects　are　constantly　conjoined　together；　and　the　mind　is
determined　by　custom　to　infer　the　one　from　the　appearance　of
the　other。　These　two　circumstances　form　the　whole　of　that
necessity；　which　we　ascribe　to　matter。　Beyond　the　constant
　of　similar　objects；　and　the　consequent
　from　one　to　the　other；　we　have　no　notion　of　any
necessity　or　connexion。

　　　　　If　it　appear；　therefore；　that　all　mankind　have　ever
allowed；　without　any　doubt　or　hesitation；　that　these　two
circumstances　take　place　in　the　voluntary　actions　of　men；
and　in　the　operations　of　mind；　it　must　follow；　that　all
mankind　have　ever　agreed　in　the　doctrine　of　necessity；　and
that　they　have　hitherto　disputed；　merely　for　not
understanding　each　other。

　　　　　As　to　the　first　circumstance；　the　constant　and　regular
conjunction　of　similar　events；　we　may　possibly　satisfy
ourselves　by　the　following　considerations：　It　is　universally
acknowledged　that　there　is　a　great　uniformity　among　the
actions　of　men；　in　all　nations　and　ages；　and　that　human
nature　remains　still　the　same；　in　its　principles　and
operations。　The　same　motives　always　produce　the　same
actions：　The　same　events　follow　from　the　same　causes。
Ambition；　avarice；　self…love；　vanity；　friendship；
generosity；　public　spirit：　These　passions；　mixed　in　various
degrees；　and　distributed　through　society；　have　been；　from
the　beginning　of　the　world；　and　still　are；　the　source　of　all
the　actions　and　enterprises；　which　have　ever　been　observed
among　mankind。　Would　you　know　the　sentiments；　inclinations；
and　course　of　life　of　the　G/REEKS　and　R/OMANS？　Study　well
the　temper　and　actions　of　the　F/RENCH　and　E/NGLISH：　You
cannot　be　much　mistaken　in　transferring　to　the　former　
of　the　observations　which　you　have　made　with　regard　to　the
latter。　Mankind　are　so　much　the　same；　in　all　times　and
places；　that　history　informs　us　of　nothing　new　or　strange　in
this　particular。　Its　chief　use　is　only　to　discover　the
constant　and　universal　principles　of　human　nature；　by
showing　men　in　all　varieties　of　circumstances　and
situations；　and　furnishing　us　with　materials　from　which　we
may　form　our　observations　and　become　acquainted　with　the
regular　springs　of　human　action　and　behaviour。　These　records
of　wars；　intrigues；　factions；　and　revolutions；　are　so　many
collections　of　experiments；　by　which　the　politician　or　moral
philosopher　fixes　the　principles　of　his　science；　in　the　same
manner　as　the　physician　or　natural　philosopher　becomes
acquainted　with　the　nature　of　plants；　minerals；　and　other
external　objects；　by　the　experiments　which　he　forms
concerning　them。　Nor　are　the　earth；　water；　and　other
elements；　examined　by　A/RISTOTLE；　and　H/IPPOCRATES；　more
like　to　those　which　at　present　lie　under　our　observation
than　the　men　described　by　P/OLYBIUS　and　T/ACITUS　are　to
those　who　now　govern　the　world。

　　　　　Should　a　traveller；　returning　from　a　far　country；　bring
us　an　account　of　men；　wholly　different　from　any　with　whom　we
were　ever　acquainted；　men；　who　were　entirely　divested　of
avarice；　ambition；　or　revenge；　who　knew　no　pleasure　but
friendship；　generosity；　and　public　spirit；　we　should
immediately；　from　these　circumstances；　detect　the　falsehood；
and　prove　him　a　liar；　with　the　same　certainty　as　if　he　had
stuffed　his　narration　with　stories　of　centaurs　and　dragons；
miracles　and　prodigies。　And　if　we　would　explode　any　forgery
in　history；　we　cannot　make　use　of　a　more　convincing
argument；　than　to　prove；　that　the　actions　ascribed　to　any
person　are　directly　contrary　to　the　course　of　nature；　and
that　no　human　motives；　in　such　circumstances；　could　ever
induce　him　to　such　a　conduct。　The　veracity　of　Q/UINTUS
C/URTIUS　is　as　much　to　be　suspected；　when　he　describes　the
supernatural　courage　of　A/LEXANDER；　by　which　he　was　hurried
on　singly　to　attack　multitudes；　as　when　he　describes　his
supernatural　force　and　activity；　by　which　he　was　able　to
resist　them。　So　readily　and　universally　do　we　acknowledge　a
uniformity　in　human　motives　and　actions　as　well　as　in　the
operations　of　body。

　　　　　Hence　likewise　the　benefit　of　that　experience；　acquired
by　long　life　and　a　variety　of　business　and　company；　in　order
to　instruct　us　in　the　principles　of　human　nature；　and
regulate　our　future　conduct；　as　well　as　speculation。　By
means　of　this　guide；　we　mount　up　to　the　knowledge　of　men's
inclinations　and　motives；　from　their　actions；　expressions；
and　even　gestures；　and　again　descend　to　the　interpretation
of　their　actions　from　our　knowledge　of　their　motives　and
inclinations。　The　general　observations　treasured　up　by　a
course　of　experience；　give　us　the　clue　of　human　nature；　and
teach　us　to　unravel　all　its　intricacies。　Pretexts　and
appearances　no　longer　deceive　us。　Public　declarations　pass
for　the　specious　colouring　of　a　cause。　And　though　virtue　and
honour　be　allowed　their　proper　weight　and　authority；　that
perfect　disinterestedness；　so　often　pretended　to；　is　never
expected　in　multitudes　and　parties；　seldom　in　their　leaders；
and　scarcely　even　in　individuals　of　any　rank　or　station。　But
were　there　no　uniformity　in　human　actions；　and　were　every
experiment　which　we　could　form　of　this　kind　irregular　and
anomalous；　it　were　impossible　to　collect　any　general
observations　concerning　mankind；　and　no　experience；　however
accurately　digested　by　reflection；　would　ever　serve　to　any
purpose。　Why　is　the　aged　husbandman　more　skilful　in　his
calling　than　the　young　beginner　but　because　there　is　a
certain　uniformity　in　the　operation　of　the　sun；　rain；　and
earth　towards　the　production　of　vegetables；　and　experience
teaches　the　old　practitioner　the　rules　by　which　this
operation　is　governed　and　directed。

　　　　　We　must　not；　however；　expect　that　this　uniformity　of
human　actions　should　be　carried　to　such　a　length　as　that　all
men；　in　the　same　circumstances；　will　always　act　precisely　in
the　same　manner；　without　making　any　allowance　for　the
diversity　of　characters；　prejudices；　and　opinions。　Such　a
uniformity　in　every　particular；　is　found　in　no　part　of
nature。　On　the　contrary；　from　observing　the　variety　of
conduct　in　different　men；　we　are　enabled　to　form　a　greater
variety　of　maxims；　which　still　suppose　a　degree　of
uniformity　and　regularity。

　　　　　Are　the　manners　of　men　different　in　different　ages　and
countries？　We　learn　thence　the　great　force　of　custom　and
education；　which　mould　the　human　mind　from　its　infancy