power, cause, effect, appear to me very analogous to the notions of
the Peripatetics, and, indeed, of the greater number of the ancient
philosophers, with respect to form; and, I trust that as we have now
universally learned to consider _form_, as nothing in itself, but only
as the relation of bodies co-existing immediately in space, so _power_
will at length be as universally considered as only the relation which
substances bear to each other _in time_, according as their phenomena
are immediately successive; the invariable antecedent being the
cause, the invariable consequent the effect; and the antecedent and
consequent being all that are present in any phenomenon. There are, in
nature, only substances; and all the substances in nature, are every
thing that truly exists in nature. There is, therefore, no additional
_power_, separate, or different from the antecedent itself, more than
there is _form_, separate or different from the figured mass, or any
other quality, without a substance. In the beautiful experiment of the
prismatic decomposition of light, for example, the refracting power
of the prism is not any thing separate or separable from it, more
than its weight or transparency of colour. There are not a prism and
transparency, but there is a prism giving passage to light. In like
manner, there are not a prism, and refracting power, and coloured
rays, but there are a prism and rays of various colours, which we
have perceived to be deflected variously from their original line of
direction, when they approach and quit the lens, and which we believe,
will, in the same circumstances, continually exhibit the same tendency.
It is the mere regularity of the successions of events, not any
additional and more mysterious circumstance, which power may be
supposed to denote, that gives the whole value to our physical
knowledge. It is of importance for us to know, _what_ antecedents
truly precede _what_ consequents; since we can thus provide for that
future, which we are hence enabled to foresee, and can, in a great
measure, modify, and almost create, the future to ourselves, by
arranging the objects over which we have command, in such a manner,
as to form with them the antecedents, which we know to be invariably
followed by the consequents desired by us. It is thus we are able to
exercise that command over nature, which _He_, who is its only real
Sovereign, has designed, in the magnificence of His bounty, to confer
on us, together with the still greater privilege of knowing that
Omnipotence to which all our delegated empire is so humbly subordinate.
It is a command which can be exercised by us, only as beings, who,
according to one of the definitions that have been given of man, look
both _before_ and _behind_; or, in the words of Cicero, who join and
connect the future with the present, seeing things, not in their
progress merely, but in the circumstances that precede them, and the
circumstances that follow them, and being thus enabled to provide and
arrange whatever is necessary for that life, of which the whole course
lies open before us. “Homo autem (quod rationis est particeps, per quam
consequentia cernit, causas rerum videt, earumque progressus et quasi
antecessiones non ignorat, similitudines comparat, et rebus præsentibus
adjungit atque annectit futuras) facile totius vitæ cursum videt, ad
eamque degendam præparat res necessarias.”[28]
That power is nothing more than the relation of one object or event
as antecedent to another object or event, though its immediate and
invariable consequent, may, perhaps, from the influence of former
habits of thought, or rather, of former abuse of language, at
first appear to you an unwarrantable simplification; for, though
you may never have clearly conceived, in power, any thing more
than the immediate sequence of a certain change or event, as its
uniform attendant, the mere habit of attaching to it many phrases of
mystery, may, very naturally, lead you to conceive, that, in itself,
independently of these phrases, there must be something peculiarly
mysterious. But the longer you attend to the notion, the more clearly
will you perceive, that all which you have ever understood in it,
is the immediate sequence of some change with the certainty of the
future recurrence of this effect, as often as the antecedent itself
may recur in similar circumstances. To take an example, which I have
already repeatedly employed, when a spark falls upon gunpowder, and
kindles it into explosion, every one ascribes to the spark the _power_
of kindling the inflammable mass. But let any one ask himself, what
it is which he means by the term, and, without contenting himself
with a few phrases that signify nothing, _reflect_, before he give
his answer, and he will find, that he means nothing more than that,
in all similar circumstances, the explosion of gunpowder will be the
immediate and uniform consequence of the application of a spark. To
take an example more immediately connected with our own science, we all
know, that as soon as any one, in the usual circumstances of health
and freedom, wills to move his arm, the motion of his arm follows; and
we all believe, that, in the same circumstance of health, and in the
same freedom from external restraint, the same _will_ to move the arm,
will be constantly followed by the same motion. If we knew and believed
nothing more, than that this motion of the arm would uniformly follow
the will to move it, would our knowledge of this particular phenomenon
be less perfect, than at present, and should we learn any thing new, by
being told, that the will would not merely be invariably followed by
the motion of the arm, but that the will would also have the power of
moving the arm; or would not the power of moving the arm be precisely
the same thing, as the invariable sequence of the motion of the arm,
when the will was immediately antecedent?
This test of identity, as I have said in my Essay on the subject,
appears to me to be a most accurate one. When a proposition is true,
and yet communicates no additional information, it must be of exactly
the same import, as some other proposition, formerly understood and
admitted. Let us suppose ourselves, then, to know all the antecedents
and consequents in nature, and to believe, not merely that they have
once or repeatedly existed in succession, but that they have uniformly
done so, and will continue forever to recur in similar series, so that,
but for the intervention of the Divine will, which would be itself,
in that case, a new antecedent, it will be absolutely impossible for
any one of the antecedents to exist again, in similar circumstances,
without being instantly followed by its original consequent. If an
effect be something more than what invariably follows a particular
antecedent, we might, on the present supposition, know every invariable
consequent of every antecedent, so as to be able to predict, in their
minutest circumstance, what events would forever follow every other
event, and yet have no conception of power or causation. We might know,
that the flame of a candle, if we hold our hand over it, would be
instantly followed by pain and burning of the hand,--that, if we ate
or drank a certain quantity, our hunger and thirst would cease:--we
might even build houses for shelter, sow and plant for sustenance, form
legislative enactments for the prevention or punishment of vice, and
bestow rewards for the encouragement of virtue;--in short, we might
do, as individuals and citizens, whatever we do at this moment, and
with exactly the same views, and yet, (on the supposition that power
is something different from that invariable antecedence which alone we
are supposed to know,) we might with all this unerring knowledge of
the future, and undoubting confidence in the results which it was to
present, have no knowledge of a single power in nature, or of a single
cause or effect. To him who had previously kindled a fire, and placed
on it a vessel full of water, with the certainty that the water, in
that situation, would speedily become hot, what additional information
would be given, by telling him that the fire had the _power_ of boiling
water, that it was the _cause_ of the boiling, and the boiling its
_effect_? And, if no additional information would in this case be
given, then, according to the test of this identity of propositions,
before stated, to know events as invariably antecedent and consequent,
is to know them as causes and effects; and to know all the powers of
every substance therefore, would be only to know what changes or events
would, in all possible circumstances, ensue, when preceded by certain
other changes or events. It is only by confounding _casual_ with
uniform and invariable antecedence, that power can be conceived, to be
something different from antecedence. It certainly is something very
different from the priority of a single moment; but it is impossible
to form any conception of it whatever, except merely as that which is
constantly followed by a certain effect.
Such is the _simple_, and, as it appears to me, the _only_ intelligible
view of _power_, as discoverable in the successive phenomena of
nature. And yet, how different from this simple view is the common,
or, I may almost say, the universal notion of the agencies, which are
supposed to be concerned in the phenomena that are the objects of
philosophic inquiry. It is the detection of the powers of nature, to
which such inquiry is supposed to lead,--but not of powers, in the
sense in which alone that phrase is intelligible, as signifying the
objects themselves which uniformly precede certain changes. The powers
which our investigation is to detect, or which, at least, in all the
phenomena that come under our observation, we are to consider as the
sole efficient, though invisible producers of them, are conceived
by us to be something far more mysterious,--something that is no
part of the antecedent, and yet is a part of it,--or that intervenes
between each antecedent and consequent, without being itself any thing
intermediate,--as if it were possible that any thing could intervene in
a series, without instantly becoming itself a part of the series,--a
new link in the lengthened chain,--the consequent of the former
antecedent, and the antecedent of the former consequent.
To me, indeed, it appears so very obvious a truth, that the substances
which exist in nature--the world, its living inhabitants, and the
adorable Being who created them,--are all the real existences in
nature, and that, in the various changes which occur, therefore, there
can as little be any powers or susceptibilities different from the
antecedents and consequents themselves, as there can be forms different
from the co-existing particles which constitute them,--that to labour
thus to impress this truth upon your minds, seems to me almost like
an attempt to demonstrate a self-evident proposition. An illusion,
however, so universal, as that which supposes the powers of nature,
to be something more, than the mere series of antecedents themselves,
is not rashly, or without very full inquiry, to be considered as an
illusion; and, at any rate, in the case of a mistake, so prevalent
and so important in its consequences, it cannot be uninteresting, to
inquire into the circumstances, that appear most probably to have led
to it. Indeed the more false, and the more obviously false the illusion
is, the more must it deserve our inquiry, _what_ those circumstances
have been which have so long obtained for it the assent, not of common
understanding merely, but of the quick-sighted and the subtile. For a
full view of my opinions on this subject, I must refer you to the work
which I have published on the Relation of Cause and Effect; and the
short abstract of them which I now offer, as it would be superfluous
for those who have read and understood that work, is chiefly for the
sake of those who may not have had an opportunity of perusing the
volume itself.
One source of the general fallacy unquestionably is that influence
of _abstraction_, to which I before alluded, as aided, and in a
great measure perpetuated, by the use of language, and the common
unavoidable modes of grammatical construction. We speak of the powers
of a substance, of substances that have certain power--of the figure
of a body, or of bodies that have a certain figure, in the same manner
as we speak of the students of a university, or of a house that has
a great number of lodgers; and we thus learn to consider the power,
which a substance possesses, as something different from the substance
itself, inherent in it indeed, but inherent, as something that may yet
subsist separately. In the ancient philosophy, this error extended to
the notions both of form and power. In the case of _form_, however, we
have seen, that the illusion, though it lasted for many ages, did at
length cease, and that no one now regards the _figure_ of a body, as
any thing but the body itself. It is probable that the illusion, with
respect to power, as something different from the substance that is
said to possess it, would, in like manner, have ceased, and given place
to juster views, if it had not been for the cause, which I am next to
consider.
This cause is the _imperfection of our senses_, the same cause which,
in the other department of physics before examined by us,--the
department, that relates to matter considered merely as existing
in space,--we find to give occasion to all our inquiries into the
compositions of bodies. In this department of physics, however, which
relates to the successions of phenomena in time, the imperfection of
our senses operates in a different way. It is not that which gives
occasion to the necessity of inquiry; for we have seen, that senses,
of the utmost accuracy and delicacy, could not, of themselves, and
without experience, have enabled us to predict any one event, in the
innumerable series of phenomena that are constantly taking place
around us. But, though senses of the nicest discrimination could not
have rendered inquiry into the successions of events superfluous, they
would have saved us from much idle inquiry, and have given far greater
precision, if not to our _rules_, at least to our uniform _practice_,
of philosophizing.
As our senses are at present constituted, they are too imperfect, to
enable us to distinguish all the elements, that co-exist in bodies,
and of elements, which are themselves unknown to us, the minute
changes which take place in them, must of course be unknown. We are
hence, from our incapacity of discovering these elements by our
imperfect senses, and imperfect analysis, incapable of distinguishing
the whole series of external changes that occur in them,--the whole
progressive series of antecedents and consequents in a phenomenon
that appears to our senses simple; and, since it is only between
immediate antecedents and consequents, that we suppose any permanent
and invariable relation, we are therefore constantly on the watch, to
detect, in the more obvious changes that appear to us in nature, some
of those minuter elementary changes, which we suspect to intervene.
These minute invisible changes, when actually intervening, are truly
what connect the obvious antecedents with the obvious consequents; and
the innumerable discoveries, which we are constantly making of these,
lead us habitually to suppose, that, amid all the visible changes
perceived by us, there is something latent which links them together.
He who for the first time listens to the delightful sounds of a violin,
if he be ignorant of the theory of sound, will very naturally suppose
that the touch of the strings by the bow is the cause of the melody
which he hears. He learns, however, that this primary impulse would be
of little effect, were it not for the vibrations excited by it in the
violin itself; and another discovery, still more important, shews him
that the vibration of the instrument would be of no effect, if it were
not for the elastic medium, interposed, between his ear and it. It is
no longer to the violin, therefore, that he looks, as the direct cause
of the sensation of sound, but to the vibrating air; nor will even this
be long considered by him as the _cause_, if he turns his attention
to the structure of the organ of hearing. He will then trace effect
after effect, through a long series of complex and very wonderful
parts, till he arrive at the auditory nerve, and the whole mass of the
brain,--in some unknown state of which he is at length forced to rest,
as the cause or immediate antecedent, of that affection of the mind,
which constitutes the particular sensation. To inquire into the latent
causes of events is thus to endeavour to observe changes which we
suppose to be actually taking place before us unobserved, very nearly
in the same manner, as to inquire into the composition of a substance
is to strive to discover the bodies that are constantly before us,
without our being able to distinguish them.
It is quite impossible, that this constant search, and frequent
detection of causes, before unknown, thus found to intervene between
all the phenomena observed by us, should not, by the influence of the
common principles of our mental constitution, at length associate,
almost indissolubly, with the very notion of changes as perceived by
us, the notion of something intermediate, that as yet lies hid from
our search, and connects the parts of the series which we at present
perceive. This latent something, supposed to intervene between the
observed antecedent and the observed consequent, being the more
immediate antecedent of the change which we observe, is of course
regarded by us as the _true cause_ of the change, while the antecedent
actually observed by us, and known, ceases, for the same reason, to
be regarded as the cause, and a cause is hence supposed by us, to be
something very mysterious; since we give the name, in our imagination,
to something of the nature of which we must be absolutely ignorant, as
we are, by supposition, ignorant of its very existence. The parts of a
series of changes, which we truly observe, are regarded by us as little
more than signs of other intervening changes as yet undetected; and our
thought is thus constantly turned from the known to the unknown, as
often as we think of discovering a cause.
The expectation of discovering something intermediate and unknown
between all known events, it thus appears, is very readily convertible
into the common notion of power, as a secret and invisible tie. Why
does it do this? or, How does it produce this effect? is the question
which we are constantly disposed to put, when we are told of any change
which one substance occasions in another; and the common answer, in
all such cases, is nothing more than the statement of some intervening
object, or event, supposed to be unknown to the asker, but as truly a
mere antecedent in the sequence, as the more obvious antecedent which
he is supposed to know. How is it that we see objects at a distance--a
tower, for example, on the summit of a hill, on the opposite side of
a river? Because rays of light are reflected from the tower to the
eye. The new antecedent appears to us a very intelligible reason. And
why do rays of light, that fall in confusion from every body, within
our sphere of vision, on every point of the surface of the eye,--from
the wood, the rock, the bridge, the river, as well as the tower,--give
distinct impressions of all these different objects? Because the eye
is formed of such refracting power, that the rays of light, which
fall confusedly on its surface, converge within it, and form distinct
images of the objects from which they come, on that part of the eye
which is an expansion of the nerve of sight. Again we are told only
of intervening events before unknown to us; and again we consider
the mere knowledge of these new antecedents as a very intelligible
explanation of the event which we knew before. This constant statement
of _something intermediate_, that is supposed to be unknown to us, as
the cause of the phenomena which we perceive, whenever we ask, how or
why they take place? continually strengthens the illusion, which leads
us to regard the powers of objects as something different from the
perceived objects themselves;--and yet it is evident, that to state
_intervening_ changes, is only to state _other_ antecedents,--not any
thing different from mere antecedence,--and that whatever number of
these intervening changes we may discover between the antecedent and
the consequent, which we at present know, we must at length come to
some ultimate change, which is truly and immediately antecedent to the
known effect. We may say, that an orator, when he declaims, excites
the sensation of sound, because the motion of his vocal organs excites
vibrations in the intervening air,--that these vibrations of air are
the cause of the sound, by communicating vibration to parts of the ear,
and that the vibrations of these parts of the ear are the cause of the
sound, by affecting in a particular manner the nerve of hearing, and
the brain in general;--but, when we come to the _ultimate_ affection of
the sensorial organ, which immediately precedes the sensation of the
mind, it is evident, that we cannot say of it, that it is the cause of
the sound, by exciting any thing intermediate, since it then could not
itself be that by which the sound was immediately preceded. It is the
cause, however; exactly in the same manner as all the other parts of
the sequence were causes, merely by being the immediate and invariable
antecedent of the particular effect. If, in our inability of assigning
any thing intermediate, we were to say, that this last affection of
the sensorial organ occasioned the sound, because it had the power of
occasioning sound, we should say nothing more than if we had said at
once, that it occasioned the sound, or, in other words, was that which
could not exist in the same circumstances without the sound as its
instant attendant.
“What is there,” says Malebranche, “which Aristotle cannot at once
propose and resolve, by his fine words of genus, species, act, power,
nature, form, faculties, qualities, causa per se, causa per accidens?
His followers find it very difficult to comprehend that these words
signify nothing; and that we are not more learned than we were before,
when we have heard them tell us, in their best manner, that fire melts
metals, because it has a solvent faculty; and that some unfortunate
epicure, or glutton digests ill, because he has a weak digestion, or
because the _vis concoctrix_ does not perform well its functions.”[29]
We see only parts of the great sequences that are taking place in
nature; and it is on this account we seek for the causes of what we
_know_ in the parts of the sequences that are _unknown_. If our senses
had originally enabled us to discriminate every element of bodies,
and consequently, all the minute changes which take place in these,
as clearly as the more obvious changes at present perceived by us;
in short, if, between two known events, we had never _discovered_
any thing intermediate and unknown, forming a new antecedent of the
consequent observed before, our notion of a cause would have been very
different from that mysterious unintelligible something which we now
conceive it to be; and we should then, perhaps, have found as little
difficulty in admitting it to be what it simply and truly is,--only
another name for the immediate invariable antecedent of any event,--as
we now find in admitting the _form_ of a body, to be only another name
for the _relative position_ of the parts that constitute it.