an enquiry concerning human understanding-第13节

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the　fallacious　deductions　of　our　reason；　which　is　slow　in
its　operations；　appears　not；　in　any　degree；　during　the　first
years　of　infancy；　and　at　best　is；　in　every　age　and　period　of
human　life；　extremely　liable　to　error　and　mistake。　It　is
more　conformable　to　the　ordinary　wisdom　of　nature　to　secure
so　necessary　an　act　of　the　mind；　by　some　instinct　or
mechanical　tendency；　which　may　be　infallible　in　its
operations；　may　discover　itself　at　the　first　appearance　of
life　and　thought；　and　may　be　independent　of　all　the　laboured
deductions　of　the　understanding。　As　nature　has　taught　us　the
use　of　our　limbs；　without　giving　us　the　knowledge　of　the
muscles　and　nerves；　by　which　they　are　actuated；　so　has　she
implanted　in　us　an　instinct；　which　carries　forward　the
thought　in　a　correspondent　course　to　that　which　she　has
established　among　external　objects；　though　we　are　ignorant
of　those　powers　and　forces；　on　which　this　regular　course　and
succession　of　objects　totally　depends。

　　　　　　　　　　　　　　　　　　　　　　　　　　*　*　*　*
　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　
　　　　　　　　　　　　　　　　　　　　　　　　SECTION　VI。
　　　　　　　　　　　　　　　　　　　　Of　Probability。＇14＇

　　　　　T/HOUGH　there　be　no　such　thing　as　Chance　in　the　world；
our　ignorance　of　the　real　cause　of　any　event　has　the　same
influence　on　the　understanding；　and　begets　a　like　species　of
belief　or　opinion。

　　　　　There　is　certainly　a　probability；　which　arises　from　a
superiority　of　chances　on　any　side；　and　according　as　this
superiority　increases；　and　surpasses　the　opposite　chances；
the　probability　receives　a　proportionable　increase；　and
begets　still　a　higher　degree　of　belief　or　assent　to　that
side；　in　which　we　discover　the　superiority。　If　a　dye　were
marked　with　one　figure　or　number　of　spots　on　four　sides；　and
with　another　figure　or　number　of　spots　on　the　two　remaining
sides；　it　would　be　more　probable；　that　the　former　would　turn
up　than　the　latter；　though；　if　it　had　a　thousand　sides
marked　in　the　same　manner；　and　only　one　side　different；　the
probability　would　be　much　higher；　and　our　belief　or
expectation　of　the　event　more　steady　and　secure。　This
process　of　the　thought　or　reasoning　may　seem　trivial　and
obvious；　but　to　those　who　consider　it　more　narrowly；　it　may；
perhaps；　afford　matter　for　curious　speculation。

　　　　　It　seems　evident；　that；　when　the　mind　looks　forward　to
discover　the　event；　which　may　result　from　the　throw　of　such
a　dye；　it　considers　the　turning　up　of　each　particular　side
as　alike　probable；　and　this　is　the　very　nature　of　chance；　to
render　all　the　particular　events；　comprehended　in　it；
entirely　equal。　But　finding　a　greater　number　of　sides　concur
in　the　one　event　than　in　the　other；　the　mind　is　carried　more
frequently　to　that　event；　and　meets　it　oftener；　in　revolving
the　various　possibilities　or　chances；　on　which　the　ultimate
result　depends。　This　concurrence　of　several　views　in　one
particular　event　begets　immediately；　by　an　inexplicable
contrivance　of　nature；　the　sentiment　of　belief；　and　gives
that　event　the　advantage　over　its　antagonist；　which　is
supported　by　a　smaller　number　of　views；　and　recurs　less
frequently　to　the　mind。　If　we　allow；　that　belief　is　nothing
but　a　firmer　and　stronger　conception　of　an　object　than　what
attends　the　mere　fictions　of　the　imagination；　this　operation
may；　perhaps；　in　some　measure；　be　accounted　for。　The
concurrence　of　these　several　views　or　glimpses　imprints　the
idea　more　strongly　on　the　imagination；　gives　it　superior
force　and　vigour；　renders　its　influence　on　the　passions　and
affections　more　sensible；　and　in　a　word；　begets　that
reliance　or　security；　which　constitutes　the　nature　of　belief
and　opinion。

　　　　　The　case　is　the　same　with　the　probability　of　causes；　as
with　that　of　chance。　There　are　some　causes；　which　are
entirely　uniform　and　constant　in　producing　a　particular
effect；　and　no　instance　has　ever　yet　been　found　of　any
failure　or　irregularity　in　their　operation。　Fire　has　always
burned；　and　water　suffocated　every　human　creature：　The
production　of　motion　by　impulse　and　gravity　is　an　universal
law；　which　has　hitherto　admitted　of　no　exception。　But　there
are　other　causes；　which　have　been　found　more　irregular　and
uncertain；　nor　has　rhubarb　always　proved　a　purge；　or　opium　a
soporific　to　every　one；　who　has　taken　these　medicines。　It　is
true；　when　any　cause　fails　of　producing　its　usual　effect；
philosophers　ascribe　not　this　to　any　irregularity　in　nature；
but　suppose；　that　some　secret　causes；　in　the　particular
structure　of　parts；　have　prevented　the　operation。　Our
reasonings；　however；　and　conclusions　concerning　the　event
are　the　same　as　if　this　principle　had　no　place。　Being
determined　by　custom　to　transfer　the　past　to　the　future；　in
all　our　inferences；　where　the　past　has　been　entirely　regular
and　uniform；　we　expect　the　event　with　the　greatest
assurance；　and　leave　no　room　for　any　contrary　supposition。
But　where　different　effects　have　been　found　to　follow　from
causes；　which　are　to　　exactly　similar；　all　these
various　effects　must　occur　to　the　mind　in　transferring　the
past　to　the　future；　and　enter　into　our　consideration；　when
we　determine　the　probability　of　the　event。　Though　we　give
the　preference　to　that　which　has　been　found　most　usual；　and
believe　that　this　effect　will　exist；　we　must　not　overlook
the　other　effects；　but　must　assign　to　each　of　them　a
particular　weight　and　authority；　in　proportion　as　we　have
found　it　to　be　more　or　less　frequent。　It　is　more　probable；
in　almost　every　country　of　E/UROPE；　that　there　will　be
frost　sometime　in　J/ANUARY；　than　that　the　weather　will
continue　open　through　out　that　whole　month；　though　this
probability　varies　according　to　the　different　climates；　and
approaches　to　a　certainty　in　the　more　northern　kingdoms。
Here　then　it　seems　evident；　that；　when　we　transfer　the　past
to　the　future；　in　order　to　determine　the　effect；　which　will
result　from　any　cause；　we　transfer　all　the　different　events；
in　the　same　proportion　as　they　have　appeared　in　the　past；
and　conceive　one　to　have　existed　a　hundred　times；　for
instance；　another　ten　times；　and　another　once。　As　a　great
number　of　views　do　here　concur　in　one　event；　they　fortify
and　confirm　it　to　the　imagination；　beget　that　sentiment
which　we　call　；　and　give　its　object　the　preference
above　the　contrary　event；　which　is　not　supported　by　an　equal
number　of　experiments；　and　recurs　not　so　frequently　to　the
thought　in　transferring　the　past　to　the　future。　Let　any　one
try　to　account　for　this　operation　of　the　mind　upon　any　of
the　received　systems　of　philosophy；　and　he　will　be　sensible
of　the　difficulty。　For　my　part；　I　shall　think　it　sufficient；
if　the　present　hints　excite　the　curiosity　of　philosophers；
and　make　them　sensible　how　defective　all　common　theories　are
in　treating　of　such　curious　and　such　sublime　subjects。
　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　
　　　　　　　　　　　　　　　　　　　　　　　　　　*　*　*　*
　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　
　　　　　　　　　　　　　　　　　　　　　　　　SECTION　VII。
　　　　　　　　　　　　Of　the　Idea　of　　Necessary　Connexion。
　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　
　　　　　　　　　　　　　　　　　　　　　　　　　　PART　I。

　　　　　T/HE　great　advantage　of　the　mathematical　sciences
above　the　moral　consists　in　this；　that　the　ideas　of　the
former；　being　sensible；　are　always　clear　and　determinate；
the　smallest　distinction　between　them　is　immediately
perceptible；　and　the　same　terms　are　still　expressive　of　the
same　ideas；　without　ambiguity　or　variation。　An　oval　is　never
mistaken　for　a　circle；　nor　an　hyperbola　for　an　ellipsis。　The
isosceles　and　scalenum　are　distinguished　by　boundaries　more
exact　than　vice　and　virtue；　right　and　wrong。　If　any　term　be
defined　in　geometry；　the　mind　readily；　of　itself；
substitutes；　on　all　occasions；　the　definition　for　the　term
defined：　Or　even　when　no　definition　is　employed；　the　object
itself　may　be　presented　to　the　senses；　and　by　that　means　be
steadily　and　clearly　apprehended。　But　the　finer　sentiments
of　the　mind；　the　operations　of　the　understanding；　the
various　agitations　of　the　passions；　though　really　in
themselves　distinct；　easily　escape　us；　when　surveyed　by
reflection；　nor　is　it　in　our　power　to　recall　the　original
object；　as　often　as　we　have　occasion　to　contemplate　it。
Ambiguity；　by　this　means；　is　gradually　introduced　into　our
reasonings：　Similar　objects　are　readily　taken　to　be　the
same：　And　the　conclusion　becomes　at　last　very　wide　of　the
premises。

　　　　　One　may　safely；　however；　affirm；　that；　if　we　consider
these　sciences　in　a　proper　light；　their　advantages　and
disadvantages　nearly　compensate　each　other；　and　reduce　both
of　them　to　a　state　of　equality。　If　the　mind；　with　greater
facility；　retains　the　ideas　of　geometry　clear　and
determinate；　it　must　carry　on　a　much　longer　and　more
intricate　chain　of　reasoning；　and　compare　ideas　much　wider
of　each　other；　in　order　to　reach　the　abstruser　truths　of
that　science。　And　if　moral　ideas　are　apt；　without　extreme
care；　to　fall　into　obscurity　and　confusion；　the　inferences
are　always　much　shorter　in　these　disquisitions；　and　the
intermediate　steps；　which　lead　to　the　conclusion；　much　fewer
than　in　the　sciences　which　treat　of　quantity　and　number。　In
reality；　there　is　scarcely　a　proposition　in　E/UCLID　so
simple；　as　not　to　consist　of　more　parts；　than　are　to　be
found　in　any　moral　reasoning　which　run