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Cause
Means Regular Association
by David Hume
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 any
thing, which we have not antecedently felt,
either by our external or internal senses. ... 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, any thing 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.
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. ...
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 by 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.
...
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 ... 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. ...
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. ...
***
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 any
thing 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.
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
longer 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.
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.
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.
Custom, then, is the great guide of human life.
It is that principle alone which renders our
experience useful to us, and makes us expect, for
the future, a similar train of events with those
which have appeared in the past.
Without the influence of custom, we should be
entirely ignorant of every matter of fact beyond
what is immediately present to the memory and
senses. We should never know how to adjust means to
ends, or to employ our natural powers in the
production of any effect. There would be an end at
once of all action, as well as of the chief part of
speculation.
But here it may be proper to remark, that though
our conclusions from experience carry us beyond our
memory and senses, and assure us of matters of fact
which happened in the most distant places and most
remote ages, yet some fact must always be present
to the senses or memory, from which we may first
proceed in drawing these conclusions. A man, who
should find in a desert country the remains of
pompous buildings, would conclude that the country
had, in ancient times, been cultivated by civilized
inhabitants; but did nothing of this nature occur
to him, he could never form such an inference. We
learn the events of former ages from history; but
then we must peruse the volumes in which this
instruction is contained, and thence carry up our
inferences from one testimony to another, till we
arrive at the eyewitnesses and spectators of these
distant events. In a word, if we proceed not upon
some fact, present to the memory or senses, our
reasonings would be merely hypothetical; and
however the particular links might be connected
with each other, the whole chain of inferences
would have nothing to support it, nor could we
ever, by its means, arrive at the knowledge of any
real existence. If I ask why you believe any
particular matter of fact, which you relate, you
must tell me some reason; and this reason will be
some other fact, connected with it. But as you
cannot proceed after this manner, in
infinitum, you must at last terminate in some
fact, which is present to your memory or senses; or
must allow that your belief is entirely without
foundation.
What, then, is the conclusion of the whole
matter? A simple one; though, it must be confessed,
pretty remote from the common theories of
philosophy. All belief of matter of fact or real
existence is derived merely from some object,
present to the memory or senses, and a customary
conjunction between that and some other object. Or
in other words; having found, in many instances,
that any two kinds of objects -- flame and heat,
snow and cold -- have always been conjoined
together; if flame or snow be presented anew to the
senses, the mind is carried by custom to expect
heat or cold, and to believe that such a
quality does exist, and will discover itself upon a
nearer approach. This belief is the necessary
result of placing the mind in such circumstances.
It is an operation of the soul, when we are so
situated, as unavoidable as to feel the passion of
love, when we receive benefits; or hatred, when we
meet with injuries. All these operations are a
species of natural instincts, which no reasoning or
process of the thought and understanding is able
either to produce or to prevent.
Excerpted from An Enquiry
Concerning Human Understanding, by David Hume
(1777)
Biography in The
Radical Academy: David Hume
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An
Enquiry concerning Human
Understanding,
by
David Hume
Order
at Powell's
The
Cambridge Companion to Hume
Order
at Powell's
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