Sect.
VII. Of
the Idea of necessary Connexion
PART I.
48 THE 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 recal 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 Euclid so
simple, as not to consist of
more
parts, than are to be found in any
moral reasoning which runs
not into
chimera and conceit. Where we
trace the principles of the
human
mind through a few steps, we may
be very well satisfied with
our
progress; considering how soon
nature throws a bar to all
our enquiries
concerning causes, and
reduces us to an
acknowledgment
of our ignorance. The chief
obstacle, therefore, to our
improvement
in the moral or metaphysical
sciences is the obscurity of
the
ideas, and ambiguity of the terms.
The principal difficulty in
the
mathematics is the length of
inferences and compass of
thought,
requisite to the forming of any
conclusion. And, perhaps,
our progress
in natural philosophy is
chiefly retarded by the want
of
proper experiments and phaenomena,
which are often discovered
by chance,
and cannot always be found, when
requisite, even by the most
diligent
and prudent enquiry. As moral
philosophy seems hitherto to
have
received less improvement than
either geometry or physics,
we may
conclude, that, if there be any
difference in this respect
among
these sciences, the difficulties,
which obstruct the progress
of the
former, require superior care and
capacity to be surmounted.
49. There are no
ideas, which
occur in metaphysics, more obscure and
uncertain, than those of
power,
force, energy or necessary
connexion, of which it is
every
moment necessary for us to treat in
all our disquisitions. We
shall,
therefore, endeavour, in this
section, to fix, if
possible, the
precise meaning of these terms,
and thereby remove some part
of
that obscurity, which is so much
complained of in this
species of
philosophy.
It seems a
proposition, which
will not admit of much dispute, that
all our ideas are nothing
but copies
of our impressions, or, in
other words, that it is
impossible
for us to think of anything,
which we have not
antecedently felt,
either by our external or
internal senses. I have
endeavoured*
to explain and prove this
proposition, and have
expressed
my hopes, that, by a proper
application of it, men may
reach
a greater clearness and precision
in philosophical reasonings,
than
what they have hitherto been able to
attain. Complex ideas may,
perhaps,
be well known by definition, which
is nothing but an
enumeration of
those parts or simple ideas, that
compose them. But when we
have pushed
up definitions to the most
simple ideas, and find still
some
ambiguity and obscurity; what
resource are we then
possessed of?
By what invention can we throw
light upon these ideas, and
render
them altogether precise and
determinate to our
intellectual
view? Produce the impressions or
original sentiments, from
which
the ideas are copied. These
impressions are all strong
and sensible.
They admit not of
ambiguity. They are not only
placed
in a full light themselves, but
may throw light on their
correspondent
ideas, which lie in
obscurity. And by this
means, we
may, perhaps, attain a new microscope
or species of optics, by
which,
in the moral sciences, the most
minute, and most simple
ideas may
be so enlarged as to fall readily
under our apprehension, and
be equally
known with the grossest and
most sensible ideas, that
can be
the object of our enquiry.
* Section II.
50. To be fully
acquainted,
therefore, with the idea of power or
necessary connexion, let us
examine
its impression; and in order to
find the impression with
greater
certainty, let us search for it in
all the sources, from which
it may
possibly be derived.
When we look about
us towards
external objects, and consider the
operation of causes, we are
never
able, in a single instance, to
discover any power or
necessary
connexion; any quality, which binds
the effect to the cause, and
renders
the one an infallible consequence
of the other. We only find,
that
the one does actually, in fact,
follow the other. The
impulse of
one billiard-ball is attended with
motion in the second. This
is the
whole that appears to the outward
senses. The mind feels no
sentiment
or inward impression from this
succession of objects:
Consequently,
there is not, in any single,
particular instance of cause
and
effect, anything which can suggest
the idea of power or
necessary connexion.
From the first
appearance
of an object, we never can conjecture what
effect will result from it.
But
were the power or energy of any
cause discoverable by the
mind,
we could foresee the effect, even
without experience; and
might, at
first, pronounce with certainty
concerning it, by mere dint
of thought
and reasoning.
In reality, there
is no part
of matter, that does ever, by its
sensible qualities, discover
any
power or energy, or give us ground to
imagine, that it could
produce any
thing, or be followed by any
other object, which we could
denominate
its effect. Solidity,
extension, motion; these
qualities
are all complete in themselves, and
never point out any other
event
which may result from them. The scenes
of the universe are
continually
shifting, and one object follows
another in an uninterrupted
succession;
but the power of force,
which actuates the whole
machine,
is entirely concealed from us, and
never discovers itself in
any of
the sensible qualities of body. We
know, that, in fact, heat is
a constant
attendant of flame; but what
is the connexion between
them, we
have no room so much as to
conjecture or imagine. It is
impossible,
therefore, that the idea of
power can be derived from
the contemplation
of bodies, in single
instances of their
operation; because
no bodies ever discover any
power, which can be the
original
of this idea.*
* Mr. Locke, in
his chapter
of power, says that, finding from
experience, that there are
several
new productions in matter, and
concluding that there must
somewhere
be a power capable of producing
them, we arrive at last by
this
reasoning at the idea of power. But no
reasoning can ever give us a
new,
original, simple idea; as this
philosopher himself
confesses. This,
therefore, can never be the
origin of that idea.
51. Since,
therefore, external
objects as they appear to the senses,
give us no idea of power or
necessary
connexion, by their operation in
particular instances, let us
see,
whether this idea be derived from
reflection on the operations
of
our own minds, and be copied from
any internal impression. It
may
be said, that we are every moment
conscious of internal power;
while
we feel, that, by the simple
command of our will, we can
move
the organs of our body, or direct the
faculties of our mind. An
act of
volition produces motion in our
limbs, or raises a new idea
in our
imagination. This influence of
the will we know by
consciousness.
Hence we acquire the idea of
power or energy; and are
certain,
that we ourselves and all other
intelligent beings are
possessed
of power. This idea, then, is an idea
of reflection, since it
arises from
reflecting on the operations of
our own mind, and on the
command
which is exercised by will, both over
the organs of the body and
faculties
of the soul.
52. We shall
proceed to examine
this pretension; and first with
regard to the influence of
volition
over the organs of the body.
This influence, we may
observe,
is a fact, which, like all other
natural events, can be known
only
be experience, and can never be
foreseen from any apparent
energy
or power in the cause, which
connects it with the effect,
and
renders the one an infallible
consequence of the other.
The motion
of our body follows upon the
command of our will. Of this
we
are every moment conscious. But the
means, by which this is
effected;
the energy, by which the will
performs so extraordinary an
operation;
of this we are so far from
being immediately conscious,
that
it must for ever escape our most
diligent enquiry.
For first; is
there any principle
in all nature more mysterious than
the union of soul with body;
by
which a supposed spiritual substance
acquires such an influence
over
a material one, that the most
refined thought is able to
actuate
the grossest matter? Were we
empowered, by a secret wish,
to
remove mountains, or control the
planets in their orbit; this
extensive
authority would not be more
extraordinary, nor more
beyond our
comprehension. But if by
consciousness we perceived
any power
or energy in the will, we must
know this power; we must
know its
connexion with the effect; we must
know the secret union of
soul and
body, and the nature of both these
substances; by which the one
is
able to operate, in so many instances,
upon the other.
Secondly, We are
not able
to move all the organs of the body with
a like authority; though we
cannot
assign any reason besides
experience, for so
remarkable a
difference between one and the
other. Why has the will an
influence
over the tongue and fingers,
not over the heart or liver?
This
question would never embarrass us,
were we conscious of a power
in
the former case, not in the latter. We
should then perceive,
independent
of experience, why the authority
of will over the organs of
the body
is circumscribed within such
particular limits. Being in
that
case fully acquainted with the
power or force, by which it
operates,
we should also know, why its
influence reaches precisely
to such
boundaries, and no farther.
A man, suddenly
struck with
palsy in the leg or arm, or who had
newly lost those members,
frequently
endeavours, at first to move
them, and employ them in
their usual
offices. Here he is as much
conscious of power to
command such
limbs, as a man in perfect health
is conscious of power to
actuate
any member which remains in its
natural state and condition.
But
consciousness never deceives.
Consequently, neither in the
one
case nor in the other, are we ever
conscious of any power. We
learn
the influence of our will from
experience alone. And
experience
only teaches us, how one event
constantly follows another;
without
instructing us in the secret
connexion, which binds them
together,
and renders them inseparable.
Thirdly, We learn
from anatomy,
that the immediate object of power
in voluntary motion, is not
the
member itself which is moved, but
certain muscles, and nerves,
and
animal spirits, and, perhaps,
something still more minute
and
more unknown, through which the motion
is successively propagated,
ere
it reach the member itself whose
motion is the immediate
object of
volition. Can there be a more
certain proof, that the
power, by
which this whole operation is
performed, so far from being
directly
and fully known by an inward
sentiment or consciousness,
is,
to the last degree, mysterious and
unintelligible? Here the
mind wills
a certain event: Immediately
another event, unknown to
ourselves,
and totally different from the
one intended, is produced:
This
event produces another, equally
unknown: Till at last,
through a
long succession, the desired event is
produced. But if the
original power
were felt, it must be known:
Were it known, its effect
also must
be known; since all power is
relative to its effect. And
vice
versa, if the effect be not known,
the power cannot be known
nor felt.
How indeed can we be conscious
of a power to move our
limbs, when
we have no such power; but only
that to move certain animal
spirits,
which, though they produce at
last the motion of our
limbs, yet
operate in such a manner as is
wholly beyond our
comprehension?
We may, therefore,
conclude
from the whole, I hope, without any
temerity, though with
assurance;
that our idea of power is not
copied from any sentiment or
consciousness
of power within
ourselves, when we give rise
to
animal motion, or apply our limbs to
their proper use and office.
That
their motion follows the command
of the will is a matter of
common
experience, like other natural
events: But the power or
energy
by which this is effected, like that
in other natural events, is
unknown
and inconceivable.*
* It may be
pretended, that
the resistance which we meet with in
bodies, obliging us
frequently to
exert our force, and call up all our
power, this gives us the
idea of
force and power. It is this nisus, or
strong endeavour, of which
we are
conscious, that is the original
impression from which this
idea
is copied. But, first, we attribute
power to a vast number of
objects,
where we never can suppose this
resistance of exertion of
force
to take place; to the Supreme Being,
who never meets with any
resistance;
to the mind in its command over
its ideas and limbs, in
common thinking
and motion, where the effect
follows immediately upon the
will,
without any exertion or summoning
up of force; to inanimate
matter,
which is not capable of this
sentiment. Secondly, This
sentiment
of an endeavour to overcome
resistance has no known
connexion
with any event: What follows it,
we know by experience; but
could
not know it a priori. It must,
however, be confessed, that
the
animal nisus, which we experience,
though it can afford no
accurate
precise idea of power, enters very
much into that vulgar,
inaccurate
idea, which is formed of it.
53. Shall we then
assert,
that we are conscious of a power or energy
in our own minds, when, by
an act
or command of our will, we raise
up a new idea, fix the mind
to the
contemplation of it, turn it on all
sides, and at last dismiss
it for
some other idea, when we think
that we have surveyed it
with sufficient
accuracy? I believe the
same arguments will prove,
that
even this command of the will gives us
no real idea of force or
energy.
First, It must be
allowed,
that, when we know a power, we know
that very circumstance in
the cause,
by which it is enabled to produce
the effect: For these are
supposed
to be synonimous. We must,
therefore, know both the
cause and
effect, and the relation between
them. But do we pretend to
be acquainted
with the nature of the
human soul and the nature of
an
idea, or the aptitude of the one to
produce the other? This is a
real
creation; a production of
something out of nothing:
Which
implies a power so great, that it
may seem, at first sight,
beyond
the reach of any being, less than
infinite. At least it must
be owned,
that such a power is not felt,
nor known, nor even
conceivable
by the mind. We only feel the event,
namely, the existence of an
idea,
consequent to a command of the will:
But the manner, in which
this operation
is performed, the power by
which it is produced, is
entirely
beyond our comprehension.
Secondly, The
command of the
mind over itself is limited, as well as
its command over the body;
and these
limits are not known by reason,
or any acquaintance with the
nature
of cause and effect, but only by
experience and observation,
as in
all other natural events and in
the operation of external
objects.
Our authority over our sentiments
and passions is much weaker
than
that over our ideas; and even the
latter authority is
circumscribed
within very narrow boundaries.
Will any one pretend to
assign the
ultimate reason of these
boundaries, or show why the
power
is deficient in one case, not in
another.
Thirdly, This
self-command
is very different at different times. A
man in health possesses more
of
it than one languishing with sickness.
We are more master of our
thoughts
in the morning than in the evening:
Fasting, than after a full
meal.
Can we give any reason for these
variations, except
experience? Where
then is the power, of which we
pretend to be conscious? Is
there
not here, either in a spiritual or
material substance, or both,
some
secret mechanism or structure of
parts, upon which the effect
depends,
and which, being entirely
unknown to us, renders the
power
or energy of the will equally unknown
and incomprehensible?
Volition is surely
an act
of the mind, with which we are
sufficiently acquainted.
Reflect
upon it. Consider it on all sides. Do
you find anything in it like
this
creative power, by which it raises
from nothing a new idea, and
with
a kind of Fiat, imitates the
omnipotence of its Maker, if
I may
be allowed so to speak, who
called forth into existence
all
the various scenes of nature? So far
from being conscious of this
energy
in the will, it requires as
certain experience as that
of which
we are possessed, to convince us
that such extraordinary
effects
do ever result from a simple act of
volition.
54. The generality
of mankind
never find any difficulty in
accounting for the more
common and
familiar operations of nature- such
as the descent of heavy
bodies,
the growth of plants, the generation
of animals, or the
nourishment of
bodies by food: But suppose that, in
all these cases, they
perceive the
very force or energy of the
cause, by which it is
connected
with its effect, and is for ever
infallible in its operation.
They
acquire, by long habit, such a
turn of mind, that, upon the
appearance
of the cause, they immediately
expect with assurance its
usual
attendant, and hardly conceive it
possible that any other
event could
result from it. It is only on
the discovery of
extraordinary phaenomena,
such as earthquakes,
pestilence, and prodigies of
any
kind, that they find themselves at
a loss to assign a proper
cause,
and to explain the manner in which
the effect is produced by
it. It
is usual for men, in such
difficulties, to have
recourse to
some invisible intelligent
principle* as the immediate
cause
of that event which surprises
them, and which, they think,
cannot
be accounted for from the common
powers of nature. But
philosophers,
who carry their scrutiny a
little farther, immediately
perceive
that, even in the most familiar
events, the energy of the
cause
is as unintelligible as in the most
unusual, and that we only
learn
by experience the frequent Conjunction
of objects, without being
ever able
to comprehend anything like
Connexion between them.
* Theos apo
mechanes (deus
ex machina).
55. Here, then,
many philosophers
think themselves obliged by reason
to have recourse, on all
occasions,
to the same principle, which the
vulgar never appeal to but
in cases
that appear miraculous and
supernatural. They
acknowledge mind
and intelligence to be, not only
the ultimate and original
cause
of all things, but the immediate and
sole cause of every event
which
appears in nature. They pretend that
those objects which are
commonly
denominated causes, are in reality
nothing but occasions; and
that
the true and direct principle of every
effect is not any power or
force
in nature, but a volition of the
Supreme Being, who wills
that such
particular objects should for
ever be conjoined with each
other.
Instead of saying that one
billiard-ball moves another
by a
force which it has derived from the
author of nature, it is the
Deity
himself, they say, who, by a
particular volition, moves
the second
ball, being determined to this
operation by the impulse of
the
first ball, in consequence of those
general laws which he has
laid down
to himself in the government of
the universe. But
philosophers advancing
still in their inquiries,
discover that, as we are
totally
ignorant of the power on which
depends the mutual operation
of
bodies, we are no less ignorant of
that power on which depends
the
operation of mind on body, or of
body on mind; nor are we
able, either
from our senses or
consciousness, to assign the
ultimate
principle in one case more
than in the other. The same
ignorance,
therefore, reduces them to
the same conclusion. They
assert
that the Deity is the immediate cause
of the union between soul
and body;
and that they are not the organs
of sense, which, being
agitated
by external objects, produce
sensations in the mind; but
that
it is a particular volition of our
omnipotent Maker, which
excites
such a sensation, in consequence of
such a motion in the organ.
In like
manner, it is not any energy in
the will that produces local
motion
in our members: It is God himself,
who is pleased to second our
will,
in itself impotent, and to
command that motion which we
erroneously
attribute to our own power
and efficacy. Nor do
philosophers
stop at this conclusion. They
sometimes extend the same
inference
to the mind itself, in its
internal operations. Our
mental
vision or conception of ideas is
nothing but a revelation
made to
us by our Maker. When we
voluntarily turn our
thoughts to
any object, and raise up its image in
the fancy, it is not the
will which
creates that idea: It is the
universal Creator, who
discovers
it to the mind, and renders it
present to us.
56. Thus,
according to these
philosophers, every thing is full of
God. Not content with the
principle,
that nothing exists but by his
will, that nothing possesses
any
power but by his concession: They rob
nature, and all created
beings,
of every power, in order to render
their dependence on the
Deity still
more sensible and immediate.
They consider not that, by
this
theory, they diminish, instead of
magnifying, the grandeur of
those
attributes, which they affect so
much to celebrate. It argues
surely
more power in the Deity to
delegate a certain degree of
power
to inferior creatures than to
produce every thing by his
own immediate
volition. It argues more
wisdom to contrive at first
the
fabric of the world with such
perfect foresight that, of
itself,
and by its proper operation, it may
serve all the purposes of
providence,
than if the great Creator were
obliged every moment to
adjust its
parts, and animate by his breath
all the wheels of that
stupendous
machine.
But if we would
have a more
philosophical confutation of this
theory, perhaps the two
following
reflections may suffice.
57. First, it
seems to me
that this theory of the universal energy
and operation of the Supreme
Being
is too bold ever to carry
conviction with it to a man,
sufficiently
apprized of the weakness
of human reason, and the
narrow
limits to which it is confined in
all its operations. Though
the chain
of arguments which conduct to
it were ever so logical,
there must
arise a strong suspicion, if not
an absolute assurance, that
it has
carried us quite beyond the reach
of our faculties, when it
leads
to conclusions so extraordinary, and
so remote from common life
and experience.
We are got into fairy land,
long ere we have reached the
last
steps of our theory; and there we
have no reason to trust our
common
methods of argument, or to think
that our usual analogies and
probabilities
have any authority. Our
line is too short to fathom
such
immense abysses. And however we may
flatter ourselves that we
are guided,
in every step which we take,
by a kind of verisimilitude
and
experience, we may be assured that
this fancied experience has
no authority
when we thus apply it to
subjects that lie entirely
out of
the sphere of experience. But on
this we shall have occasion
to touch
afterwards.*
* Section XII.
Secondly, I cannot
perceive
any force in the arguments on which this
theory is founded. We are
ignorant,
it is true, of the manner in which
bodies operate on each
other: Their
force or energy is entirely
incomprehensible: But are we
not
equally ignorant of the manner or
force by which a mind, even
the
supreme mind, operates either on
itself or on body? Whence, I
beseech
you, do we acquire any idea of
it? We have no sentiment or
consciousness
of this power in
ourselves. We have no idea
of the
Supreme Being but what we learn from
reflection on our own
faculties.
Were our ignorance, therefore, a good
reason for rejecting
anything, we
should be led into that principle of
denying all energy in the
Supreme
Being as much as in the grossest
matter. We surely comprehend
as
little the operations of one as of the
other. Is it more difficult
to conceive
that motion may arise from
impulse than that it may
arise from
volition? All we know is our
profound ignorance in both
cases.*
* I need not
examine at length
the vis inertiae which is so much
talked of in the new
philosophy,
and which is ascribed to matter. We
find by experience, that a
body
at rest or in motion continues for
ever in its present state,
till
put from it by some new cause; and
that a body impelled takes
as much
motion from the impelling body as
it acquires itself. These
are facts.
When we call this a vis inertiae,
we only mark these facts,
without
pretending to have any idea of the
inert power; in the same
manner
as, when we talk of gravity, we mean
certain effects, without
comprehending
that active power. It was never
the meaning of Sir Isaac
Newton
to rob second causes of all force or
energy; though some of his
followers
have endeavoured to establish
that theory upon his
authority.
On the contrary, that great
philosopher had recourse to
an etherial
active fluid to explain his
universal attraction; though
he
was so cautious and modest as to
allow, that it was a mere
hypothesis,
not to be insisted on, without
more experiments. I must
confess,
that there is something in the
fate of opinions a little
extraordinary.
Descartes insinuated that
doctrine of the universal
and sole
efficacy of the Deity, without
insisting on it. Malebranche
and
other Cartesians made it the
foundation of all their
philosophy.
It had, however, no authority in
England. Locke, Clarke, and
Cudworth,
never so much as take notice
of it, but suppose all
along, that
matter has a real, though
subordinate and derived
power. By
what means has it become so
prevalent among our modern
metaphysicians?
PART II.
58. But to hasten
to a conclusion
of this argument, which is already
drawn out to too great a
length:
We have sought in vain for an idea of
power or necessary connexion
in
all the sources from which we could
suppose it to be derived. It
appears
that, in single instances of
the operation of bodies, we
never
can, by our utmost scrutiny,
discover anything but one
event
following another, without being
able to comprehend any force
or
power by which the cause operates,
or any connexion between it
and
its supposed effect. The same
difficulty occurs in
contemplating
the operations of mind on body-
where we observe the motion
of the
latter to follow upon the
volition of the former, but
are
not able to observe or conceive the
tie which binds together the
motion
and volition, or the energy by
which the mind produces this
effect.
The authority of the will over
its own faculties and ideas
is not
a whit more comprehensible: So
that, upon the whole, there
appears
not, throughout all nature, any
one instance of connexion
which
is conceivable by us. All events
seem entirely loose and
separate.
One event follows another; but we
never can observe any tie
between
them. They seem conjoined, but never
connected. And as we can
have no
idea of any thing which never
appeared to our outward
sense or
inward sentiment, the necessary
conclusion seems to be that
we have
no idea of connexion or power at
all, and that these words
are absolutely
without any meaning, when
employed either in
philosophical
reasonings or common life.
59. But there
still remains
one method of avoiding this
conclusion, and one source
which
we have not yet examined. When any
natural object or event is
presented,
it is impossible for us, by
any sagacity or penetration,
to
discover, or even conjecture,
without experience, what
event will
result from it, or to carry our
foresight beyond that object
which
is immediately present to the
memory and senses. Even
after one
instance or experiment where we have
observed a particular event
to follow
upon another, we are not
entitled to form a general
rule,
or foretell what will happen in
like cases; it being justly
esteemed
an unpardonable temerity to judge
of the whole course of
nature from
one single experiment, however
accurate or certain. But
when one
particular species of event has
always, in all instances,
been conjoined
with another, we make no
any scruple of foretelling
one upon
the appearance of the other, and
of employing that reasoning,
which
can alone assure us of any matter
of fact or existence. We
then call
the one object, Cause; the other,
Effect. We suppose that
there is
some connexion between them; some
power in the one, by which
it infallibly
produces the other, and
operates with the greatest
certainty
and strongest necessity.
It appears, then,
that this
idea of a necessary connexion among
events arises from a number
of similar
instances which occur of the
constant conjunction of
these events;
nor can that idea ever be
suggested by any one of
these instances,
surveyed in all possible
lights and positions. But
there
is nothing in a number of instances,
different from every single
instance,
which is supposed to be
exactly similar; except
only, that
after a repetition of similar
instances, the mind is
carried by
habit, upon the appearance of one
event, to expect its usual
attendant,
and to believe that it will
exist. This connexion,
therefore,
which we feel in the mind, this
customary transition of the
imagination
from one object to its usual
attendant, is the sentiment
or impression
from which we form the
idea of power or necessary
connexion.
Nothing farther is in the
case. Contemplate the
subject on
all sides; you will never find any
other origin of that idea.
This
is the sole difference between one
instance, from which we can
never
receive the idea of connexion, and a
number of similar instances,
by
which it is suggested. The first
time a man saw the
communication
of motion by impulse, as by the shock
of two billiard balls, he
could
not pronounce that the one event was
connected: but only that it
was
conjoined with the other. After he has
observed several instances
of this
nature, he then pronounces them
to be connected. What
alteration
has happened to give rise to this new
idea of connexion? Nothing
but that
he now feels these events to be
connected in his
imagination, and
can readily foretell the existence
of one from the appearance
of the
other. When we say, therefore,
that one object is connected
with
another, we mean only that they have
acquired a connexion in our
thought,
and give rise to this
inference, by which they
become
proofs of each other's existence: A
conclusion which is somewhat
extraordinary,
but which seems founded on
sufficient evidence. Nor
will its
evidence be weakened by any
general diffidence of the
understanding,
or sceptical suspicion
concerning every conclusion
which
is new and extraordinary. No
conclusions can be more
agreeable
to scepticism than such as make
discoveries concerning the
weakness
and narrow limits of human
reason and capacity.
60. And what
stronger instance
can be produced of the surprising
ignorance and weakness of
the understanding
than the present? For
surely, if there be any
relation
among objects which it imports to
us to know perfectly, it is
that
of cause and effect. On this are
founded all our reasonings
concerning
matter of fact or existence.
By means of it alone we
attain any
assurance concerning objects
which are removed from the
present
testimony of our memory and senses.
The only immediate utility
of all
sciences, is to teach us, how to
control and regulate future
events
by their causes. Our thoughts and
enquiries are, therefore,
every
moment, employed about this
relation: Yet so imperfect
are the
ideas which we form concerning
it, that it is impossible to
give
any just definition of cause, except
what is drawn from something
extraneous
and foreign to it. Similar
objects are always conjoined
with
similar. Of this we have experience.
Suitably to this experience,
therefore,
we may define a cause to be an
object, followed by another,
and
where all the objects similar to
the first are followed by
objects
similar to the second. Or in other
words where, if the first
object
had not been, the second never had
existed. The appearance of a
cause
always conveys the mind, by a
customary transition, to the
idea
of the effect. Of this also we
have experience. We may,
therefore,
suitably to this experience,
form another definition of
cause,
and call it, an object followed by
another, and whose
appearance always
conveys the thought to that
other. But though both these
definitions
be drawn from circumstances
foreign to the cause, we
cannot
remedy this inconvenience, or attain
any more perfect definition,
which
may point out that circumstance
in the cause, which gives it
a connexion
with its effect. We have no
idea of this connexion, nor
even
any distinct notion what it is we
desire to know, when we
endeavour
at a conception of it. We say, for
instance, that the vibration
of
this string is the cause of this
particular sound. But what
do we
mean by that affirmation? We either
mean that this vibration is
followed
by this sound, and that all
similar vibrations have been
followed
by similar sounds: Or, that this
vibration is followed by
this sound,
and that upon the appearance of
one the mind anticipates the
senses,
and forms immediately an idea
of the other. We may
consider the
relation of cause and effect in
either of these two lights;
but
beyond these, we have no idea of it.*
* According to
these explications
and definitions, the idea of power
is relative as much as that
of cause;
and both have a reference to
an effect, or some other
event constantly
conjoined with the former.
When we consider the unknown
circumstance
of an object, by which the
degree or quantity of its
effect
is fixed and determined, we call that
its power: And accordingly,
it is
allowed by all philosophers, that
the effect is the measure of
the
power. But if they had any idea of
power, as it is in itself,
why could
not they Measure it in itself?
The dispute whether the
force of
a body in motion be as its
velocity, or the square of
its velocity;
this dispute, I say, need not
be decided by comparing its
effects
in equal or unequal times; but
by a direct mensuration and
comparison.
As to the frequent
use of
the words, Force, Power, Energy, &c.,
which every where occur in
common
conversation, as well as in
philosophy; that is no
proof, that
we are acquainted, in any instance,
with the connecting
principle between
cause and effect, or can account
ultimately for the
production of
one thing to another. These words, as
commonly used, have very
loose meanings
annexed to them; and their
ideas are very uncertain and
confused.
No animal can put external
bodies in motion without the
sentiment
of a nisus or endeavour; and
every animal has a sentiment
or
feeling from the stroke or blow of
an external object that is
in motion.
These sensations, which are
merely animal, and from
which we
can a priori draw no inference, we
are apt to transfer to
inanimate
objects, and to suppose, that they
have some such feelings,
whenever
they transfer or receive motion.
With regard to energies,
which are
exerted, without our annexing to
them any idea of
communicated motion,
we consider only the constant
experienced conjunction of
the events;
and as we feel a customary
connexion between the ideas,
we
transfer that feeling to the
objects; as nothing is more
usual
than to apply to external bodies
every internal sensation,
which
they occasion.
61. To
recapitulate, therefore,
the reasonings of this section:
Every idea is copied from
some preceding
impression or sentiment;
and where we cannot find any
impression,
we may be certain that
there is no idea. In all
single
instances of the operation of bodies
or minds, there is nothing
that
produces any impression, nor
consequently can suggest any
idea
of power or necessary connexion. But
when many uniform instances
appear,
and the same object is always
followed by the same event;
we then
begin to entertain the notion of
cause and connexion. We then
feel
a new sentiment or impression, to
wit, a customary connexion
in the
thought or imagination between one
object and its usual
attendant;
and this sentiment is the original
of that idea which we seek
for.
For as this idea arises from a
number of similar instances,
and
not from any single instance, it must
arise from that
circumstance, in
which the number of instances
differ from every individual
instance.
But this customary connexion or
transition of the
imagination is
the only circumstance in which they
differ. In every other
particular
they are alike. The first instance
which we saw of motion
communicated
by the shock of two billiard balls
(to return to this obvious
illustration)
is exactly similar to any
instance that may, at
present, occur
to us; except only, that we could
not, at first, infer one
event from
the other; which we are enabled to
do at present, after so long
a course
of uniform experience. I know
not whether the reader will
readily
apprehend this reasoning. I am
afraid that, should I
multiply words
about it, or throw it into a
greater variety of lights,
it would
only become more obscure and
intricate. In all abstract
reasonings
there is one point of view
which, if we can happily
hit, we
shall go farther towards illustrating
the subject than by all the
eloquence
and copious expression in the
world. This point of view we
should
endeavour to reach, and reserve
the flowers of rhetoric for
subjects
which are more adapted to them.
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