an enquiry concerning human understanding-第6章

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that　implicit　faith　and　security；　which　is　the　bane　of　all
reasoning　and　free　enquiry。　The　discovery　of　defects　in　the
common　philosophy；　if　any　such　there　be；　will　not；　I
presume；　be　a　discouragement；　but　rather　an　incitement；　as
is　usual；　to　attempt　something　more　full　and　satisfactory
than　has　yet　been　proposed　to　the　public。

　　　　　All　reasonings　concerning　matter　of　fact　seem　to　be
founded　on　the　relation　of　。　By　means　of
that　relation　alone　we　can　go　beyond　the　evidence　of　our
memory　and　senses。　If　you　were　to　ask　a　man；　why　he　believes
any　matter　of　fact；　which　is　absent；　for　instance；　that　his
friend　is　in　the　country；　or　in　F/RANCE；　he　would　give　you
a　reason；　and　this　reason　would　be　some　other　fact；　as　a
letter　received　from　him；　or　the　knowledge　of　his　former
resolutions　and　promises。　A　man　finding　a　watch　or　any　other
machine　in　a　desert　island；　would　conclude　that　there　had
once　been　men　in　that　island。　All　our　reasonings　concerning
fact　are　of　the　same　nature。　And　here　it　is　constantly
supposed　that　there　is　a　connexion　between　the　present　fact
and　that　which　is　inferred　from　it。　Were　there　nothing　to
bind　them　together；　the　inference　would　be　entirely
precarious。　The　hearing　of　an　articulate　voice　and　rational
discourse　in　the　dark　assures　us　of　the　presence　of　some
person：　Why？　because　these　are　the　effects　of　the　human　make
and　fabric；　and　closely　connected　with　it。　If　we　anatomize
all　the　other　reasonings　of　this　nature；　we　shall　find　that
they　are　founded　on　the　relation　of　cause　and　effect；　and
that　this　relation　is　either　near　or　remote；　direct　or
collateral。　Heat　and　light　are　collateral　effects　of　fire；
and　the　one　effect　may　justly　be　inferred　from　the　other。

　　　　　If　we　would　satisfy　ourselves；　therefore；　concerning
the　nature　of　that　evidence；　which　assures　us　of　matters　of
fact；　we　must　enquire　how　we　arrive　at　the　knowledge　of
cause　and　effect。

　　　　　I　shall　venture　to　affirm；　as　a　general　proposition；
which　admits　of　no　exception；　that　the　knowledge　of　this
relation　is　not；　in　any　instance；　attained　by　reasonings　；　but　arises　entirely　from　experience；　when　we　find
that　any　particular　objects　are　constantly　conjoined　with
each　other。　Let　an　object　be　presented　to　a　man　of　ever　so
strong　natural　reason　and　abilities；　if　that　object　be
entirely　new　to　him；　he　will　not　be　able；　by　the　most
accurate　examination　of　its　sensible　qualities；　to　discover
any　of　its　causes　or　effects。　A/DAM；　though　his　rational
faculties　be　supposed；　at　the　very　first；　entirely　perfect；
could　not　have　inferred　from　the　fluidity　and　transparency
of　water　that　it　would　suffocate　him；　or　from　the　light　and
warmth　of　fire　that　it　would　consume　him。　No　object　ever
discovers；　by　the　qualities　which　appear　to　the　senses；
either　the　causes　which　produced　it；　or　the　effects　which
will　arise　from　it；　nor　can　our　reason；　unassisted　by
experience；　ever　draw　any　inference　concerning　real
existence　and　matter　of　fact。

　　　　　This　proposition；　；　will　readily
be　admitted　with　regard　to　such　objects；　as　we　remember　to
have　once　been　altogether　unknown　to　us；　since　we　must　be
conscious　of　the　utter　inability；　which　we　then　lay　under；
of　foretelling　what　would　arise　from　them。　Present　two
smooth　pieces　of　marble　to　a　man　who　has　no　tincture　of
natural　philosophy；　he　will　never　discover　that　they　will
adhere　together　in　such　a　manner　as　to　require　great　force
to　separate　them　in　a　direct　line；　while　they　make　so　small
a　resistance　to　a　lateral　pressure。　Such　events；　as　bear
little　analogy　to　the　common　course　of　nature；　are　also
readily　confessed　to　be　known　only　by　experience；　nor　does
any　man　imagine　that　the　explosion　of　gunpowder；　or　the
attraction　of　a　loadstone；　could　ever　be　discovered　by
arguments　。　In　like　manner；　when　an　effect　is
supposed　to　depend　upon　an　intricate　machinery　or　secret
structure　of　parts；　we　make　no　difficulty　in　attributing　all
our　knowledge　of　it　to　experience。　Who　will　assert　that　he
can　give　the　ultimate　reason；　why　milk　or　bread　is　proper
nourishment　for　a　man；　not　for　a　lion　or　a　tyger？

　　　　　But　the　same　truth　may　not　appear；　at　first　sight；　to
have　the　same　evidence　with　regard　to　events；　which　have
become　familiar　to　us　from　our　first　appearance　in　the
world；　which　bear　a　close　analogy　to　the　whole　course　of
nature；　and　which　are　supposed　to　depend　on　the　simple
qualities　of　objects；　without　any　secret　structure　of　parts。
We　are　apt　to　imagine　that　we　could　discover　these　effects
by　the　mere　operation　of　our　reason；　without　experience。　We
fancy；　that　were　we　brought　on　a　sudden　into　this　world；　we
could　at　first　have　inferred　that　one　Billiard…ball　would
communicate　motion　to　another　upon　impulse；　and　that　we
needed　not　to　have　waited　for　the　event；　in　order　to
pronounce　with　certainty　concerning　it。　Such　is　the
influence　of　custom；　that；　where　it　is　strongest；　it　not
only　covers　our　natural　ignorance；　but　even　conceals　itself；
and　seems　not　to　take　place；　merely　because　it　is　found　in
the　highest　degree。

　　　　　But　to　convince　us　that　all　the　laws　of　nature；　and　all
the　operations　of　bodies　without　exception；　are　known　only
by　experience；　the　following　reflections　may；　perhaps；
suffice。　Were　any　object　presented　to　us；　and　were　we
required　to　pronounce　concerning　the　effect；　which　will
result　from　it；　without　consulting　past　observation；　after
what　manner；　I　beseech　you；　must　the　mind　proceed　in　this
operation？　It　must　invent　or　imagine　some　event；　which　it
ascribes　to　the　object　as　its　effect；　and　it　is　plain　that
this　invention　must　be　entirely　arbitrary。　The　mind　can
never　possibly　find　the　effect　in　the　supposed　cause；　by　the
most　accurate　scrutiny　and　examination。　For　the　effect　is
totally　different　from　the　cause；　and　consequently　can　never
be　discovered　in　it。　Motion　in　the　second　Billiard…ball　is　a
quite　distinct　event　from　motion　in　the　first；　nor　is　there
any　thing　in　the　one　to　suggest　the　smallest　hint　of　the
other。　A　stone　or　piece　of　metal　raised　into　the　air；　and
left　without　any　support；　immediately　falls：　But　to　consider
the　matter　；　is　there　any　thing　we　discover　in
this　situation　which　can　beget　the　idea　of　a　downward；
rather　than　an　upward；　or　any　other　motion；　in　the　stone　or
metal？

　　　　　And　as　the　first　imagination　or　invention　of　a
particular　effect；　in　all　natural　operations；　is　arbitrary；
where　we　consult　not　experience；　so　must　we　also　esteem　the
supposed　tie　or　connexion　between　the　cause　and　effect；
which　binds　them　together；　and　renders　it　impossible　that
any　other　effect　could　result　from　the　operation　of　that
cause。　When　I　see；　for　instance；　a　Billiard…ball　moving　in　a
straight　line　towards　another；　even　suppose　motion　in　the
second　ball　should　by　accident　be　suggested　to　me；　as　the
result　of　their　contact　or　impulse；　may　I　not　conceive；　that
a　hundred　different　events　might　as　well　follow　from　that
cause？　May　not　both　these　balls　remain　at　absolute　rest？　May
not　the　first　ball　return　in　a　straight　line；　or　leap　off
from　the　second　in　any　line　or　direction？　All　these
suppositions　are　consistent　and　conceivable。　Why　then　should
we　give　the　preference　to　one；　which　is　no　more　consistent
or　conceivable　than　the　rest？　All　our　reasonings　
will　never　be　able　to　show　us　any　foundation　for　this
preference。

　　　　　In　a　word；　then；　every　effect　is　a　distinct　event　from
its　cause。　It　could　not；　therefore；　be　discovered　in　the
cause；　and　the　first　invention　or　conception　of　it；　；　must　be　entirely　arbitrary。　And　even　after　it　is
suggested；　the　conjunction　of　it　with　the　cause　must　appear
equally　arbitrary；　since　there　are　always　many　other
effects；　which；　to　reason；　must　seem　fully　as　consistent　and
natural。　In　vain；　therefore；　should　we　pretend　to　determine

any　single　event；　or　infer　any　cause　or　effect；　without　the
assistance　of　observation　and　experience。

　　　　　Hence　we　may　discover　the　reason　why　no　philosopher；
who　is　rational　and　modest；　has　ever　pretended　to　assign　the
ultimate　cause　of　any　natural　operation；　or　to　show
distinctly　the　action　of　that　power；　which　produces　any
single　effect　in　the　universe。　It　is　confessed；　that　the
utmost　effort　of　human　reason　is　to　reduce　the　principles；
productive　of　natural　phenomena；　to　a　greater　simplicity；
and　to　resolve　the　many　particular　effects　into　a　few
general　causes；　by　means　of　reasonings　from　analogy；
experience；　and　observation。　But　as　to　the　causes　of　these
general　causes；　we　should　in　vain　attempt　their　discovery；
nor　shall　we　ever　be　able　to　satisfy　ourselves；　by　any
particular　explication　of　them。　These　ultimate　springs　and
principles　are　totally　shut　up　from　human　curiosity　and
enquiry。　Elasticity；　gravity；　cohesion　of　parts；
communication　of　motion　by　impulse；　these　are　probably　the
ultimate　causes　and　principles　which　we　shall　ever　discover
in　nature；　and　we　may　esteem　ourselves　sufficiently　happy；
if；　by　accurate　enquiry　and　reasoning；　we　can　trace　up　the
particular　phenomena　to；　or　near　to；　these　general
principles。　The　most　perfect　philosophy　of　the　natural　kind
only　staves　off　our　ignorance　a　little　longer：　As　perhaps
the　most　perfect　philosophy　of　the　moral　or　metaphysical
kind　serves　only　to　discover　larger　portions　of　it。　Thus　the
observation　of　human　blindness　and　weakness　is　the　result　of
all　philosophy；　and　meets　us　at　every　turn；　in　spite　of　our
endeavours　to　elude　or　avoid　it。

　　　　　Nor　is　geometry；　when　taken　into　the　assistance　of
natural　philosophy；　ever　able　to　remedy　this　defect；　or　lead
us　into　the　knowledge　of　ultimate　causes；　by　all　that
accuracy　of　reasoning　for　which　it　is　so　justly　celebrated。
Every　part　of　mixed　mathematics　proceeds　upon　the
supposition　that　certain　laws　are　established　by　nature　in
her　operations；　and　abstract　reasonings　are　employed；　either
to　assist　experience　in　the　discovery　of　these　laws；　or　to
determine　their　influence　in　particular　instances；　where　it
depends　upon　any　precise　degree　of　distance　and　quantity。
Thus；　it　is　a　law　of　motion；　discovered　by　experience；　that
the　moment　or　force　of　any　body　in　motion　is　in　the　compound
ratio　or　proportion　of　its　solid　contents　and　its　velocity；
and　consequently；　that　a　small　force　may　remove　the　greatest
obstacle　or　raise　the　greatest　weight；　if；　by　any
contrivance　or　machinery；　we　can　increase　the　velocity　of
that　force；　so　as　to　make　it　an　overmatch　for　its
antagonist。　Geometry　assists　us　in　the　application　of　this
law；　by　giving　us　the　just　dimensions　of　all　the　parts　and
figures　which　can　enter　into　any　species　of　machine；　but
still　the　discovery　of　the　law　itself　is　owing　merely　to
experience；　and　all　the　abstract　reasonings　in　the　world
could　never　lead　us　one　step　towards　the　knowledge　of　it。
When　we　reason　；　and　consider　merely　any　object　or
cause；　as　it　appears　to　the　mind；　independent　of　all
observation；　it　never　could　suggest　to　us　the　notion　of　any
distinct　object；　such　as　its　effect；　much　less；　show　us　the
inseparable　and　inviolable　connexion　between　them。　A　man
must　be　very　sagacious　who