study of the brutes are applicable to man, and that the logical
consequences of such application are fatalism, materialism, and
atheism—whereupon the drums will beat the _pas de charge_.
One does not do battle with drummers; but I venture to offer a few
remarks for the calm consideration of thoughtful persons, untrammelled
by foregone conclusions, unpledged to shore-up tottering dogmas, and
anxious only to know the true bearings of the case.
It is quite true that, to the best of my judgment, the argumentation
which applies to brutes holds equally good of men; and, therefore, that
all states of consciousness in us, as in them, are immediately caused
by molecular changes of the brain-substance. It seems to me that in
men, as in brutes, there is no proof that any state of consciousness
is the cause of change in the motion of the matter of the organism. If
these positions are well based, it follows that our mental conditions
are simply the symbols in consciousness of the changes which take
place automatically in the organism; and that, to take an extreme
illustration, the feeling we call volition is not the cause of a
voluntary act, but the symbol of that state of the brain which is
the immediate cause of that act. We are conscious automata, endowed
with free will in the only intelligible sense of that much-abused
term—inasmuch as in many respects we are able to do as we like—but
none the less parts of the great series of causes and effects which, in
unbroken continuity, composes that which is, and has been, and shall
be—the sum of existence.
As to the logical consequences of this conviction of mine, I may be
permitted to remark that logical consequences are the scarecrows of
fools and the beacons of wise men. The only question which any wise man
can ask himself, and which any honest man will ask himself, is whether
a doctrine is true or false. Consequences will take care of themselves;
at most their importance can only justify us in testing with extra care
the reasoning process from which they result.
So that if the view I have taken did really and logically lead to
fatalism, materialism, and atheism, I should profess myself a fatalist,
materialist, and atheist; and I should look upon those who, while they
believed in my honesty of purpose and intellectual competency, should
raise a hue and cry against me, as people who by their own admission
preferred lying to truth, and whose opinions therefore were unworthy of
the smallest attention.
But, as I have endeavoured to explain on other occasions, I really have
no claim to rank myself among fatalistic, materialistic, or atheistic
philosophers. Not among fatalists, for I take the conception of
necessity to have a logical, and not a physical foundation; not among
materialists, for I am utterly incapable of conceiving the existence
of matter if there is no mind in which to picture that existence; not
among atheists, for the problem of the ultimate cause of existence is
one which seems to me to be hopelessly out of reach of my poor powers.
Of all the senseless babble I have ever had occasion to read, the
demonstrations of these philosophers who undertake to tell us all about
the nature of God would be the worst, if they were not surpassed by the
still greater absurdities of the philosophers who try to prove that
there is no God.
And if this personal disclaimer should not be enough, let me further
point out that a great many persons whose acuteness and learning will
not be contested, and whose Christian piety, and, in some cases, strict
orthodoxy, are above suspicion, have held more or less definitely the
view that man is a conscious automaton.
It is held, for example, in substance, by the whole school of
predestinarian theologians, typified by St. Augustine, Calvin, and
Jonathan Edwards—the great work of the latter on the will showing
in this, as in other cases, that the growth of physical science has
introduced no new difficulties of principle into theological problems,
but has merely given visible body, as it were, to those which already
existed.
Among philosophers, the pious Geulincx and the whole school of
occasionalist Cartesians held this view; the orthodox Leibnitz invented
the term “automate spirituel,” and applied it to man; the fervent
Christian, Hartley, was one of the chief advocates and best expositors
of the doctrine; while another zealous apologist of Christianity in
a sceptical age, and a contemporary of Hartley, Charles Bonnet, the
Genevese naturalist, has embodied the doctrine in language of such
precision and simplicity, that I will quote the little-known passage of
his “Essai de Psychologie” at length:—
“ANOTHER HYPOTHESIS CONCERNING THE MECHANISM OF IDEAS.[55]
“Philosophers accustomed to judge of things by that which
they are in themselves, and not by their relation to
received ideas, would not be shocked if they met with
the proposition that the soul is a mere spectator of
the movements of its body: that the latter performs of
itself all that series of actions which constitutes life:
that it moves of itself: that it is the body alone which
reproduces ideas, compares and arranges them; which forms
reasonings, imagines and executes plans of all kinds,
etc. This hypothesis, though perhaps of an excessive
boldness, nevertheless deserves some consideration.
“It is not to be denied that Supreme Power could create
an automaton which should exactly imitate all the
external and internal actions of man.
“I understand by external actions, all those movements
which pass under our eyes; I term internal actions, all
the motions which in the natural state cannot be observed
because they take place in the interior of the body—such
as the movements of digestion, circulation, sensation,
etc. Moreover, I include in this category the movements
which give rise to ideas, whatever be their nature.
“In the automaton which we are considering everything
would be precisely determined. Everything would occur
according to the rules of the most admirable mechanism:
one state would succeed another state, one operation
would lead to another operation, according to invariable
laws; motion would become alternately cause and effect,
effect and cause; reaction would answer to action, and
reproduction to production.
“Constructed with definite relations to the activity
of the beings which compose the world, the automaton
would receive impressions from it, and, in faithful
correspondence thereto, it would execute a corresponding
series of motions.
“Indifferent towards any determination, it would yield
equally to all, if the first impressions did not, so to
speak, wind up the machine and decide its operations and
its course.
“The series of movements which this automaton could
execute would distinguish it from all others formed on
the same model, but which, not having been placed in
similar circumstances, would not have experienced the
same impressions, or would not have experienced them in
the same order.
“The senses of the automaton, set in motion by the
objects presented to it, would communicate their motion
to the brain, the chief motor apparatus of the machine.
This would put in action the muscles of the hands and
feet, in virtue of their secret connection with the
senses. These muscles, alternately contracted and
dilated, would approximate or remove the automaton from
the objects, in the relation which they would bear to the
conservation or the destruction of the machine.
“The motions of perception and sensation which the
objects would have impressed on the brain, would be
preserved in it by the energy of its mechanism. They
would become more vivid according to the actual condition
of the automaton, considered in itself and relatively to
the objects.
“Words being only the motions impressed on the organ
of hearing and that of voice, the diversity of these
movements, their combination, the order in which they
would succeed one another, would represent judgments,
reasoning, and all the operations of the mind.
“A close correspondence between the organs of the senses,
either by the opening into one another of their nervous
ramifications, or by interposed springs (_ressorts_),
would establish such a connection in their working, that,
on the occasion of the movements impressed on one of
these organs, other movements would be excited, or would
become more vivid in some of the other senses.
“Give the automaton a soul which contemplates its
movements, which believes itself to be the author of
them, which has different volitions on the occasion of
the different movements, and you will on this hypothesis
construct a man.
“But would this man be free? Can the feeling of our
liberty, this feeling which is so clear and so distinct
and so vivid as to persuade us that we are the authors of
our actions, be conciliated with this hypothesis? If it
removes the difficulty which attends the conception of
the action of the soul on the body, on the other hand it
leaves untouched that which meets us in endeavouring to
conceive the action of the body on the soul.”
But if Leibnitz, Jonathan Edwards, and Hartley—men who rank among
the giants of the world of thought—could see no antagonism between
the doctrine under discussion and Christian orthodoxy, is it not
just possible that smaller folk may be wrong in making such a coil
about “logical consequences”? And, seeing how large a share of this
clamour is raised by the clergy of one denomination or another, may
I say, in conclusion, that it really would be well if ecclesiastical
persons would reflect that ordination, whatever deep-seated graces
it may confer, has never been observed to be followed by any visible
increase in the learning or the logic of its subject. Making a man a
Bishop, or entrusting him with the office of ministering to even the
largest of Presbyterian congregations, or setting him up to lecture to
a Church congress, really does not in the smallest degree augment such
title to respect as his opinions may intrinsically possess. And, when
such a man presumes on an authority which was conferred upon him for
other purposes, to sit in judgment upon matters his incompetence to
deal with which is patent, it is permissible to ignore his sacerdotal
pretensions, and to tell him, as one would tell a mere common,
unconsecrated, layman: that it is not necessary for any man to occupy
himself with problems of this kind unless he so choose; life is filled
full enough by the performance of its ordinary and obvious duties. But
that, if a man elect to become a judge of these grave questions; still
more, if he assume the responsibility of attaching praise or blame
to his fellow-men for the conclusions at which they arrive touching
them, he will commit a sin more grievous than most breaches of the
Decalogue, unless he avoid a lazy reliance upon the information that
is gathered by prejudice and filtered through passion, unless he go
back to the prime sources of knowledge—the facts of nature, and the
thoughts of those wise men who for generations past have been her best
interpreters.
X.
ON SENSATION AND THE UNITY OF STRUCTURE OF SENSIFEROUS ORGANS.
The maxim that metaphysical inquiries are barren of result, and that
the serious occupation of the mind with them is a mere waste of time
and labour, finds much favour in the eyes of the many persons who
pride themselves on the possession of sound common sense; and we
sometimes hear it enunciated by weighty authorities, as if its natural
consequence, the suppression of such studies, had the force of a moral
obligation.
In this case, however, as in some others, those who lay down the law
seem to forget that a wise legislator will consider, not merely whether
his proposed enactment is desirable, but whether obedience to it is
possible. For, if the latter question is answered negatively, the
former is surely hardly worth debate.
Here, in fact, lies the pith of the reply to those who would make
metaphysics contraband of intellect. Whether it is desirable to
place a prohibitory duty upon philosophical speculations or not, it
is utterly impossible to prevent the importation of them into the
mind. And it is not a little curious to observe that those who most
loudly profess to abstain from such commodities are, all the while,
unconscious consumers, on a great scale, of one or other of their
multitudinous disguises or adulterations. With mouths full of the
particular kind of heavily buttered toast which they affect, they
inveigh against the eating of plain bread. In truth, the attempt to
nourish the human intellect upon a diet which contains no metaphysics
is about as hopeful as that of certain Eastern sages to nourish their
bodies without destroying life. Everybody has heard the story of the
pitiless microscopist, who ruined the peace of mind of one of these
mild enthusiasts by showing him the animals moving in a drop of the
water with which, in the innocency of his heart, he slaked his thirst;
and the unsuspecting devotee of plain common sense may look for as
unexpected a shock when the magnifier of severe logic reveals the
germs, if not the full-grown shapes, of lively metaphysical postulates
rampant amidst his most positive and matter-of-fact notions.
By way of escape from the metaphysical Will-o’-the-wisps generated
in the marshes of literature and theology, the serious student is
sometimes bidden to betake himself to the solid ground of physical
science. But the fish of immortal memory, who threw himself out of the
frying-pan into the fire, was not more ill advised than the man who
seeks sanctuary from philosophical persecution within the walls of
the observatory or of the laboratory. It is said that “metaphysics”
owe their name to the fact that, in Aristotle’s works, questions of
pure philosophy are dealt with immediately after those of physics. If
so, the accident is happily symbolical of the essential relations of
things; for metaphysical speculation follows as closely upon physical
theory as black care upon the horseman.
One need but mention such fundamental, and indeed indispensable,
conceptions of the natural philosopher as those of atoms and forces:
or that of attraction considered as action at a distance; or that of
potential energy; or the antinomies of a vacuum and a plenum; to call
to mind the metaphysical background of physics and chemistry; while, in
the biological sciences, the case is still worse. What is an individual
among the lower plants and animals? Are genera and species realities or
abstractions? Is there such a thing as Vital Force? or does the name
denote a mere relic of metaphysical fetichism? Is the doctrine of final
causes legitimate or illegitimate? These are a few of the metaphysical
topics which are suggested by the most elementary study of biological
facts. But, more than this, it may be truly said that the roots of
every system of philosophy lie deep among the facts of physiology. No
one can doubt that the organs and the functions of sensation are as
much a part of the province of the physiologist, as are the organs and
functions of motion, or those of digestion; and yet it is impossible
to gain an acquaintance with even the rudiments of the physiology of
sensation without being led straight to one of the most fundamental of
all metaphysical problems. In fact, the sensory operations have been,
from time immemorial, the battle-ground of philosophers.
I have more than once taken occasion to point out that we are
indebted to Descartes, who happened to be a physiologist as well as
a philosopher, for the first distinct enunciation of the essential
elements of the true theory of sensation. In later times, it is not to
the works of the philosophers, if Hartley and James Mill are excepted,
but to those of the physiologists, that we must turn for an adequate
account of the sensory process. Haller’s luminous, though summary,
account of sensation in his admirable “Primæ Lineæ,” the first edition
of which was printed in 1747, offers a striking contrast to the
prolixity and confusion of thought which pervade Reid’s “Inquiry,” of
seventeen years’ later date.[56] Even Sir William Hamilton, learned
historian and acute critic as he was, not only failed to apprehend the
philosophical bearing of long-established physiological truths; but,
when he affirmed that there is no reason to deny that the mind feels at
the finger points, and none to assert that the brain is the sole organ
of thought,[57] he showed that he had not apprehended the significance
of the revolution commenced, two hundred years before his time, by
Descartes, and effectively followed up by Haller, Hartley, and Bonnet,
in the middle of the last century.
In truth, the theory of sensation, except in one point, is, at the
present moment, very much where Hartley, led by a hint of Sir Isaac
Newton’s, left it, when, a hundred and twenty years since, the
“Observations on Man: his Frame, his Duty, and his Expectations,” was
laid before the world. The whole matter is put in a nutshell in the
following passages of this notable book.
“External objects impressed upon the senses occasion,
first on the nerves on which they are impressed, and then
on the brain, vibrations of the small and, as we may say,
infinitesimal medullary particles.
“These vibrations are motions backwards and forwards
of the small particles; of the same kind with the
oscillations of pendulums and the tremblings of the
particles of sounding bodies. They must be conceived to
be exceedingly short and small, so as not to have the
least efficacy to disturb or move the whole bodies of the
nerves or brain.”[58]
“The white medullary substance of the brain is also the
immediate instrument by which ideas are presented to
the mind; or, in other words, whatever changes are made
in this substance, corresponding changes are made in our
ideas; and _vice versa_.”[59]
Hartley, like Haller, had no conception of the nature and functions of
the grey matter of the brain. But, if for “white medullary substance,”
in the latter paragraph, we substitute “grey cellular substance,”
Hartley’s propositions embody the most probable conclusions which are
to be drawn from the latest investigations of physiologists. In order
to judge how completely this is the case, it will be well to study some
simple case of sensation, and, following the example of Reid and of
James Mill, we may begin with the sense of smell. Suppose that I become
aware of a musky scent, to which the name of “muskiness” may be given.
I call this an odour, and I class it along with the feelings of light,
colours, sounds, tastes, and the like, among those phenomena which are
known as sensations. To say that I am aware of this phenomenon, or that
I have it, or that it exists, are simply different modes of affirming
the same facts. If I am asked how I know that it exists, I can only
reply that its existence and my knowledge of it are one and the same
thing; in short, that my knowledge is immediate or intuitive, and, as
such, is possessed of the highest conceivable degree of certainty.
The pure sensation of muskiness is almost sure to be followed by
a mental state which is not a sensation, but a belief, that there
is somewhere close at hand a something on which the existence of
the sensation depends. It may be a musk-deer, or a musk-rat, or a
musk-plant, or a grain of dry musk, or simply a scented handkerchief;
but former experience leads us to believe that the sensation is due to
the presence of one or other of these objects, and that it will vanish
if the object is removed. In other words, there arises a belief in an
external cause of the muskiness, which, in common language, is termed
an odorous body.
But the manner in which this belief is usually put into words is
strangely misleading. If we are dealing with a musk-plant, for example,
we do not confine ourselves to a simple statement of that which we
believe, and say that the musk-plant is the cause of the sensation
called muskiness; but we say that the plant has a musky smell, and
we speak of the odour as a quality, or property, inherent in the
plant. And the inevitable reaction of words upon thought has in this
case become so complete, and has penetrated so deeply, that when an
accurate statement of the case—namely, that muskiness, inasmuch as
the term denotes nothing but a sensation, is a mental state, and has
no existence except as a mental phenomenon—is first brought under the
notice of common-sense folks, it is usually regarded by them as what
they are pleased to call a mere metaphysical paradox and a patent
example of useless subtlety. Yet the slightest reflection must suffice
to convince any one possessed of sound reasoning faculties, that it is
as absurd to suppose that muskiness is a quality inherent in one plant,
as it would be to imagine that pain is a quality inherent in another,
because we feel pain when a thorn pricks the finger.
Even the common-sense philosopher, _par excellence_, says of smell: “It
appears to be a simple and original affection or feeling of the mind,
altogether inexplicable and unaccountable. It is indeed impossible that
it can be in any body: it is a sensation, and a sensation can only be
in a sentient thing.”[60]
That which is true of muskiness is true of every other odour.
Lavender-smell, clove-smell, garlic-smell, are, like “muskiness,” names
of states of consciousness, and have no existence except as such.
But, in ordinary language, we speak of all these odours as if they
were independent entities residing in lavender, cloves, and garlic;
and it is not without a certain struggle that the false metaphysic of
so-called common sense, thus ingrained in us, is expelled.
For the present purpose, it is unnecessary to inquire into the origin
of our belief in external bodies, or into that of the notion of
causation. Assuming the existence of an external world, there is no
difficulty in obtaining experimental proof that, as a general rule,
olfactory sensations are caused by odorous bodies; and we may pass on
to the next step of the inquiry—namely, how the odorous body produces
the effect attributed to it.
The first point to be noted here is another fact revealed by
experience; that the appearance of the sensation is governed, not only
by the presence of the odorous substance, but by the condition of a
certain part of our corporeal structure, the nose. If the nostrils are
closed, the presence of the odorous substance does not give rise to
the sensation; while, when they are open, the sensation is intensified
by the approximation of the odorous substance to them, and by snuffing
up the adjacent air in such a manner as to draw it into the nose. On
the other hand, looking at an odorous substance, or rubbing it on the
skin, or holding it to the ear, does not awaken the sensation. Thus,
it can be readily established by experiment that the perviousness of
the nasal passages is, in some way, essential to the sensory function;
in fact, that the organ of that function is lodged somewhere in the
nasal passages. And, since odorous bodies give rise to their effects at
considerable distances, the suggestion is obvious that something must
pass from them into the sense organ. What is this “something,” which
plays the part of an intermediary between the odorous body and the
sensory organ?
The oldest speculation about the matter dates back to Democritus and
the Epicurean School, and it is to be found fully stated in the fourth
book of Lucretius. It comes to this: that the surfaces of bodies
are constantly throwing off excessively attenuated films of their
own substance: and that these films, reaching the mind, excite the
appropriate sensations in it.
Aristotle did not admit the existence of any such material films, but
conceived that it was the form of the substance, and not its matter,
which affected sense, as a seal impresses wax, without losing anything
in the process. While many, if not the majority, of the Schoolmen took
up an intermediate position and supposed that a something, which was
not exactly either material or immaterial, and which they called an
“intentional species,” effected the needful communication between the
bodily cause of sensation and the mind.