results of modern research, they would have furnished him with far
more powerful arguments than he possessed in favour of his view of
the automatism of brutes. The habits of a frog, leading its natural
life, involve such simple adaptations to surrounding conditions,
that the machinery which is competent to do so much without the
intervention of consciousness, might well do all. And this argument is
vastly strengthened by what has been learned in recent times of the
marvellously complex operations which are performed mechanically, and
to all appearance without consciousness, by men, when, in consequence
of injury or disease, they are reduced to a condition more or less
comparable to that of a frog, in which the anterior part of the brain
has been removed. A case has recently been published by an eminent
French physician, Dr. Mesnet, which illustrates this condition so
remarkably, that I make no apology for dwelling upon it at considerable
length.[52]
A sergeant of the French army, F——, twenty-seven years of age, was
wounded during the battle of Bazeilles, by a ball which fractured his
left parietal bone. He ran his bayonet through the Prussian soldier who
wounded him, but almost immediately his right arm became paralysed;
after walking about two hundred yards, his right leg became similarly
affected, and he lost his senses. When he recovered them, three weeks
afterwards, in hospital at Mayence, the right half of the body was
completely paralysed, and remained in this condition for a year. At
present, the only trace of the paralysis which remains is a slight
weakness of the right half of the body. Three or four months after
the wound was inflicted, periodical disturbances of the functions of
the brain made their appearance, and have continued ever since. The
disturbances last from fifteen to thirty hours; the intervals at which
they occur being from fifteen to thirty days.
For four years, therefore, the life of this man has been divided into
alternating phases—short abnormal states intervening between long
normal states.
In the periods of normal life, the ex-sergeant’s health is perfect; he
is intelligent and kindly, and performs, satisfactorily, the duties of
a hospital attendant. The commencement of the abnormal state is ushered
in by uneasiness and a sense of weight about the forehead, which the
patient compares to the constriction of a circle of iron; and, after
its termination, he complains, for some hours, of dulness and heaviness
of the head. But the transition from the normal to the abnormal state
takes place in a few minutes, without convulsions or cries, and without
anything to indicate the change to a bystander. His movements remain
free and his expression calm, except for a contraction of the brow, an
incessant movement of the eyeballs, and a chewing motion of the jaws.
The eyes are wide open, and their pupils dilated. If the man happens to
be in a place to which he is accustomed, he walks about as usual; but,
if he is in a new place, or if obstacles are intentionally placed in
his way, he stumbles gently against them, stops, and then, feeling over
the objects with his hands, passes on one side of them. He offers no
resistance to any change of direction which may be impressed upon him,
or to the forcible acceleration or retardation of his movements. He
eats, drinks, smokes, walks about, dresses and undresses himself, rises
and goes to bed at the accustomed hours. Nevertheless, pins may be
run into his body, or strong electric shocks sent through it, without
causing the least indication of pain; no odorous substance, pleasant or
unpleasant, makes the least impression; he eats and drinks with avidity
whatever is offered, and takes asafœtida, or vinegar, or quinine, as
readily as water; no noise affects him; and light influences him only
under certain conditions. Dr. Mesnet remarks, that the sense of touch
alone seems to persist, and indeed to be more acute and delicate than
in the normal state; and it is by means of the nerves of touch, almost
exclusively, that his organism is brought into relation with the
external world. Here a difficulty arises. It is clear from the facts
detailed, that the nervous apparatus by which, in the normal state,
sensations of touch are excited, is that by which external influences
determine the movements of the body, in the abnormal state. But does
the state of consciousness, which we term a tactile sensation,
accompany the operation of this nervous apparatus in the abnormal
state? or is consciousness utterly absent, the man being reduced to an
insensible mechanism?
It is impossible to obtain direct evidence in favour of the one
conclusion or the other; all that can be said is, that the case of the
frog shows that the man may be devoid of any kind of consciousness.
A further difficult problem is this. The man is insensible to sensory
impressions made through the ear, the nose, the tongue, and, to a great
extent, the eye; nor is he susceptible of pain from causes operating
during his abnormal state. Nevertheless, it is possible so to act upon
his tactile apparatus, as to give rise to those molecular changes in
his sensorium, which are ordinarily the causes of associated trains of
ideas. I give a striking example of this process in Dr. Mesnet’s words:—
“Il se promenait dans le jardin, sous un massif d’arbres,
on lui remet à la main sa canne qu’il avait laissé
tomber quelques minutes avant. Il la palpe, promène à
plusieurs reprises la main sur la poignée coudée de
sa canne—devient attentif—semble prêter l’oreille—et,
tout-à-coup, appelle ‘Henri!’ Puis, ‘Les voilà! Ils sont
au moins une vingtaine! à nous deux, nous en viendrons à
bout!’ Et alors portant la main derrière son dos comme
pour prendre une cartouche, il fait le mouvement de
charger son arme, se couche dans l’herbe à plat ventre,
la tête cachée par un arbre, dans la position d’un
tirailleur, et suit, l’arme épaulée, tous les mouvements
de l’ennemi qu’il croit voir à courte distance.”
In a subsequent abnormal period, Dr. Mesnet caused the patient to
repeat this scene by placing him in the same conditions. Now, in this
case, the question arises whether the series of actions constituting
this singular pantomime was accompanied by the ordinary states of
consciousness, the appropriate train of ideas, or not? Did the man
dream that he was skirmishing? or was he in the condition of one of
Vaucauson’s automata—a senseless mechanism worked by molecular changes
in his nervous system? The analogy of the frog shows that the latter
assumption is perfectly justifiable.
The ex-sergeant has a good voice, and had, at one time, been employed
as a singer at a café. In one of his abnormal states he was observed
to begin humming a tune. He then went to his room, dressed himself
carefully, and took up some parts of a periodical novel, which lay on
his bed, as if he were trying to find something. Dr. Mesnet, suspecting
that he was seeking his music, made up one of these into a roll and
put it into his hand. He appeared satisfied, took up his cane and went
down-stairs to the door. Here Dr. Mesnet turned him round, and he
walked quite contentedly, in the opposite direction, towards the room
of the concièrge. The light of the sun shining through a window now
happened to fall upon him, and seemed to suggest the footlights of the
stage on which he was accustomed to make his appearance. He stopped,
opened his roll of imaginary music, put himself into the attitude of a
singer, and sang, with perfect execution, three songs, one after the
other. After which he wiped his face with his handkerchief and drank,
without a grimace, a tumbler of strong vinegar and water which was put
into his hand.
An experiment which may be performed upon the frog deprived of the
fore part of its brain, well known as Göltz’s “Quak-versuch,” affords
a parallel to this performance. If the skin of a certain part of the
back of such a frog is gently stroked with the finger, it immediately
croaks. It never croaks unless it is so stroked, and the croak always
follows the stroke, just as the sound of a repeater follows the
touching of the spring. In the frog, this “song” is innate—so to speak
_à priori_—and depends upon a mechanism in the brain governing the
vocal apparatus, which is set at work by the molecular change set up in
the sensory nerves of the skin of the back by the contact of a foreign
body.
In man there is also a vocal mechanism, and the cry of an infant is
in the same sense innate and _à priori_, inasmuch as it depends on an
organic relation between its sensory nerves and the nervous mechanism
which governs the vocal apparatus. Learning to speak, and learning to
sing, are processes by which the vocal mechanism is set to new tunes.
A song which has been learned has its molecular equivalent, which
potentially represents it in the brain, just as a musical box wound up
potentially represents an overture. Touch the stop and the overture
begins; send a molecular impulse along the proper afferent nerve and
the singer begins his song.
Again, the manner in which the frog, though apparently insensible to
light, is yet, under some circumstances, influenced by visual images,
finds a singular parallel in the case of the ex-sergeant.
Sitting at a table, in one of his abnormal states, he took up a
pen, felt for paper and ink, and began to write a letter to his
general, in which he recommended himself for a medal, on account of
his good conduct and courage. It occurred to Dr. Mesnet to ascertain
experimentally how far vision was concerned in this act of writing. He
therefore interposed a screen between the man’s eyes and his hands;
under these circumstances he went on writing for a short time, but the
words became illegible, and he finally stopped, without manifesting
any discontent. On the withdrawal of the screen he began to write
again where he had left off. The substitution of water for ink in the
inkstand had a similar result. He stopped, looked at his pen, wiped it
on his coat, dipped it in the water, and began again, with the same
effect.
On one occasion, he began to write upon the topmost of ten superimposed
sheets of paper. After he had written a line or two, this sheet was
suddenly drawn away. There was a slight expression of surprise, but he
continued his letter on the second sheet exactly as if it had been the
first. This operation was repeated five times, so that the fifth sheet
contained nothing but the writer’s signature at the bottom of the page.
Nevertheless, when the signature was finished, his eyes turned to the
top of the blank sheet, and he went through the form of reading over
what he had written, a movement of the lips accompanying each word;
moreover, with his pen, he put in such corrections as were needed, in
that part of the blank page which corresponded with the position of the
words which required correction, in the sheets which had been taken
away. If the five sheets had been transparent, therefore, they would,
when superposed, have formed a properly written and corrected letter.
Immediately after he had written his letter, F—— got up, walked down
to the garden, made himself a cigarette, lighted and smoked it. He was
about to prepare another, but sought in vain for his tobacco-pouch,
which had been purposely taken away. The pouch was now thrust before
his eyes and put under his nose, but he neither saw nor smelt it; but,
when it was placed in his hand, he at once seized it, made a fresh
cigarette, and ignited a match to light the latter. The match was blown
out, and another lighted match placed close before his eyes, but he
made no attempt to take it; and, if his cigarette was lighted for him,
he made no attempt to smoke. All this time the eyes were vacant, and
neither winked, nor exhibited any contraction of the pupils. From these
and other experiments, Dr. Mesnet draws the conclusion that his patient
sees some things and not others; that the sense of sight is accessible
to all things which are brought into relation with him by the sense of
touch, and, on the contrary, insensible to things which lie outside
this relation. He sees the match he holds, and does not see any other.
Just so the frog “sees” the book which is in the way of his jump, at
the same time that isolated visual impressions take no effect upon
him.[53]
As I have pointed out, it is impossible to prove that F—— is absolutely
unconscious in his abnormal state, but it is no less impossible to
prove the contrary; and the case of the frog goes a long way to
justify the assumption that, in the abnormal state, the man is a mere
insensible machine.
If such facts as these had come under the knowledge of Descartes, would
they not have formed an apt commentary upon that remarkable passage in
the “Traité de l’Homme,” which I have quoted elsewhere,[54] but which
is worth repetition?—
“All the functions which I have attributed to this
machine (the body), as the digestion of food, the
pulsation of the heart and of the arteries; the nutrition
and the growth of the limbs; respiration, wakefulness,
and sleep; the reception of light, sounds, odours,
flavours, heat, and such like qualities, in the organs of
the external senses; the impression of the ideas of these
in the organ of common sensation and in the imagination;
the retention or the impression of these ideas on the
memory: the internal movements of the appetites and the
passions; and lastly the external movements of all the
limbs, which follow so aptly, as well the action of
the objects which are presented to the senses, as the
impressions which meet in the memory, that they imitate
as nearly as possible those of a real man; I desire, I
say, that you should consider that these functions in the
machine naturally proceed from the mere arrangement of
its organs, neither more nor less than do the movements
of a clock, or other automaton, from that of its weights
and its wheels; so that, so far as these are concerned,
it is not necessary to conceive any other vegetative or
sensitive soul, nor any other principle of motion or of
life, than the blood and the spirits agitated by the fire
which burns continually in the heart, and which is no
wise essentially different from all the fires which exist
in inanimate bodies.”
And would Descartes not have been justified in asking why we need deny
that animals are machines, when men, in a state of unconsciousness,
perform, mechanically, actions as complicated and as seemingly rational
as those of any animals?
But though I do not think that Descartes’ hypothesis can be positively
refuted, I am not disposed to accept it. The doctrine of continuity
is too well established for it to be permissible to me to suppose
that any complex natural phenomenon comes into existence suddenly,
and without being preceded by simpler modifications; and very strong
arguments would be needed to prove that such complex phenomena, as
those of consciousness, first make their appearance in man. We know,
that, in the individual man, consciousness grows from a dim glimmer to
its full light, whether we consider the infant advancing in years, or
the adult emerging from slumber and swoon. We know, further, that the
lower animals possess, though less developed, that part of the brain
which we have every reason to believe to be the organ of consciousness
in man; and as, in other cases, function and organ are proportional, so
we have a right to conclude it is with the brain; and that the brutes,
though they may not possess our intensity of consciousness, and though,
from the absence of language, they can have no trains of thoughts, but
only trains of feelings, yet have a consciousness which, more or less
distinctly, foreshadows our own.
I confess that, in view of the struggle for existence which goes on
in the animal world, and of the frightful quantity of pain with which
it must be accompanied, I should be glad if the probabilities were in
favour of Descartes’ hypothesis; but, on the other hand, considering
the terrible practical consequences to domestic animals which might
ensue from any error on our part, it is as well to err on the right
side, if we err at all, and deal with them as weaker brethren, who are
bound, like the rest of us, to pay their toll for living, and suffer
what is needful for the general good. As Hartley finely says, “We
seem to be in the place of God to them;” and we may justly follow the
precedents He sets in nature in our dealings with them.
But though we may see reason to disagree with Descartes’ hypothesis
that brutes are unconscious machines, it does not follow that he
was wrong in regarding them as automata. They may be more or less
conscious, sensitive, automata; and the view that they are such
conscious machines is that which is implicitly, or explicitly, adopted
by most persons. When we speak of the actions of the lower animals
being guided by instinct and not by reason, what we really mean is
that, though they feel as we do, yet their actions are the results
of their physical organisation. We believe, in short, that they are
machines, one part of which (the nervous system) not only sets the rest
in motion, and co-ordinates its movements in relation with changes
in surrounding bodies, but is provided with special apparatus, the
function of which is the calling into existence of those states of
consciousness which are termed sensations, emotions, and ideas. I
believe that this generally accepted view is the best expression of the
facts at present known.
It is experimentally demonstrable—any one who cares to run a pin into
himself may perform a sufficient demonstration of the fact—that a mode
of motion of the nervous system is the immediate antecedent of a state
of consciousness. All but the adherents of “Occasionalism,” or of the
doctrine of “Pre-established Harmony” (if any such now exist), must
admit that we have as much reason for regarding the mode of motion
of the nervous system as the cause of the state of consciousness, as
we have for regarding any event as the cause of another. How the one
phenomenon causes the other we know, as much or as little, as in any
other case of causation; but we have as much right to believe that the
sensation is an effect of the molecular change, as we have to believe
that motion is an effect of impact; and there is as much propriety in
saying that the brain evolves sensation, as there is in saying that an
iron rod, when hammered, evolves heat.
As I have endeavoured to show, we are justified in supposing that
something analogous to what happens in ourselves takes place in the
brutes, and that the affections of their sensory nerves give rise to
molecular changes in the brain, which again give rise to, or evolve,
the corresponding states of consciousness. Nor can there be any
reasonable doubt that the emotions of brutes, and such ideas as they
possess, are similarly dependent upon molecular brain changes. Each
sensory impression leaves behind a record in the structure of the
brain—an “ideagenous” molecule, so to speak, which is competent, under
certain conditions, to reproduce, in a fainter condition, the state of
consciousness which corresponds with that sensory impression; and it is
these “ideagenous molecules” which are the physical basis of memory.
It may be assumed, then, that molecular changes in the brain are the
causes of all the states of consciousness of brutes. Is there any
evidence that these states of consciousness may, conversely, cause
those molecular changes which give rise to muscular motion? I see
no such evidence. The frog walks, hops, swims, and goes through his
gymnastic performances quite as well without consciousness, and
consequently without volition, as with it; and, if a frog, in his
natural state, possesses anything corresponding with what we call
volition, there is no reason to think that it is anything but a
concomitant of the molecular changes in the brain which form part of
the series involved in the production of motion.
The consciousness of brutes would appear to be related to the mechanism
of their body simply as a collateral product of its working, and to
be as completely without any power of modifying that working as the
steam-whistle which accompanies the work of a locomotive engine is
without influence upon its machinery. Their volition, if they have
any, is an emotion indicative of physical changes, not a cause of such
changes.
This conception of the relations of states of consciousness with
molecular changes in the brain—of _psychoses_ with _neuroses_—does not
prevent us from ascribing free will to brutes. For an agent is free
when there is nothing to prevent him from doing that which he desires
to do. If a greyhound chases a hare, he is a free agent, because his
action is in entire accordance with his strong desire to catch the
hare; while so long as he is held back by the leash he is not free,
being prevented by external force from following his inclination.
And the ascription of freedom to the greyhound under the former
circumstances is by no means inconsistent with the other aspect of
the facts of the case—that he is a machine impelled to the chase, and
caused, at the same time, to have the desire to catch the game by the
impression which the rays of light proceeding from the hare make upon
his eyes, and through them upon his brain.
Much ingenious argument has, at various times, been bestowed upon the
question: How is it possible to imagine that volition, which is a state
of consciousness, and, as such, has not the slightest community of
nature with matter in motion, can act upon the moving matter of which
the body is composed, as it is assumed to do in voluntary acts? But
if, as is here suggested, the voluntary acts of brutes—or, in other
words, the acts which they desire to perform—are as purely mechanical
as the rest of their actions, and are simply accompanied by the state
of consciousness called volition, the inquiry, so far as they are
concerned, becomes superfluous. Their volitions do not enter into the
chain of causation of their actions at all.
The hypothesis that brutes are conscious automata is perfectly
consistent with any view that may be held respecting the often
discussed and curious question whether they have souls or not; and,
if they have souls, whether those souls are immortal or not. It is
obviously harmonious with the most literal adherence to the text
of Scripture concerning “the beast that perisheth;” but it is not
inconsistent with the amiable conviction ascribed by Pope to his
“untutored savage,” that when he passes to the happy hunting-grounds
in the sky, “his faithful dog shall bear him company.” If the brutes
have consciousness and no souls, then it is clear that, in them,
consciousness is a direct function of material changes; while, if
they possess immaterial subjects of consciousness, or souls, then,
as consciousness is brought into existence only as the consequence
of molecular motion of the brain, it follows that it is an indirect
product of material changes. The soul stands related to the body as the
bell of a clock to the works, and consciousness answers to the sound
which the bell gives out when it is struck.
Thus far I have strictly confined myself to the problem with which I
proposed to deal at starting—the automatism of brutes. The question
is, I believe, a perfectly open one, and I feel happy in running
no risk of either Papal or Presbyterian condemnation for the views
which I have ventured to put forward. And there are so very few
interesting questions which one is, at present, allowed to think out
scientifically—to go as far as reason leads, and stop where evidence
comes to an end—without speedily being deafened by the tattoo of “the
drum ecclesiastic”—that I have luxuriated in my rare freedom, and would
now willingly bring this disquisition to an end if I could hope that
other people would go no farther. Unfortunately, past experience debars
me from entertaining any such hope, even if
“... that drum’s discordant sound
Parading round and round and round,”
were not, at present, as audible to me, as it was to the mild poet who
ventured to express his hatred of drums in general, in that well-known
couplet.