Critiques and Addresses by Thomas Henry Huxley
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Thomas Henry Huxley >> Critiques and Addresses
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And, on the other hand, if the blind acceptance of authority appears
to him in its true colours, as mere private judgment _in excelsis_,
and if he have the courage to stand alone, face to face with the abyss
of the Eternal and Unknowable, let him be content, once for all, not
only to renounce the good things promised by "Infallibility," but even
to bear the bad things which it prophesies; content to follow reason
and fact in singleness and honesty of purpose, wherever they may lead,
in the sure faith that a hell of honest men will, to him, be more
endurable than a paradise full of angelic shams.
Mr. Mivart asserts that "without a belief in a personal God, there is
no religion worthy of the name." This is a matter of opinion. But
it may be asserted, with less reason to fear contradiction, that the
worship of a personal God, who, on Mr. Mivart's hypothesis, must
have used language studiously calculated to deceive His creatures and
worshippers, is "no religion worthy of the name." "Incredibile est,
Deum illis verbis ad populum fuisse locutum quibus deciperetur," is a
verdict in which, for once, Jesuit casuistry concurs with the healthy
moral sense of all mankind.
Having happily got quit of the theological aspect of evolution, the
supporter of that great truth who turns to the scientific objections
which are brought against it by recent criticism, finds, to his
relief, that the work before him is greatly lightened by the
spontaneous retreat of the enemy from nine-tenths of the territory
which he occupied ten years ago. Even the Quarterly Reviewer not only
abstains from venturing to deny that evolution has taken place, but he
openly admits that Mr. Darwin has forced on men's minds "a recognition
of the probability, if not more, of evolution, and of the certainty of
the action of natural selection" (p. 49).
I do not quite see, myself, how, if the action of natural selection is
_certain_, the occurrence of evolution is only _probable_; inasmuch as
the development of a new species by natural selection is, so far as
it goes, evolution. However, it is not worth while to quarrel with
the precise terms of a sentence which shows that the high watermark of
intelligence among those most respectable of Britons, the readers of
the _Quarterly Review_, has now reached such a level that the next
tide may lift them easily and pleasantly on the once-dreaded shore of
evolution. Nor, having got there, do they seem likely to stop, until
they have reached the inmost heart of that great region, and accepted
the ape ancestry of, at any rate, the body of man. For the Reviewer
admits that Mr. Darwin can be said to have established:
"That if the various kinds of lower animals have been evolved
one from the other by a process of natural generation or
evolution, then it becomes highly probable, _a priori_, that
man's body has been similarly evolved; but this, in such a
case, becomes equally probable from the admitted fact that he
is an animal at all" (p. 65).
From the principles laid down in the last sentence, it would follow
that if man were constructed upon a plan as different from that of any
other animal as that of a sea-urchin is from that of a whale, it
would be "equally probable" that he had been developed from some other
animal as it is now, when we know that for every bone, muscle, tooth,
and even pattern of tooth, in man, there is a corresponding bone,
muscle, tooth, and pattern of tooth, in an ape. And this shows one
of two things--either that the Quarterly Reviewer's notions of
probability are peculiar to himself; or, that he has such an
overpowering faith in the truth of evolution, that no extent of
structural break between one animal and another is sufficient to
destroy his conviction that evolution has taken place.
But this by the way. The importance of the admission that there is
nothing in man's physical structure to interfere with his having been
evolved from an ape, is not lessened because it is grudgingly made and
inconsistently qualified. And instead of jubilating over the extent of
the enemy's retreat, it will be more worth while to lay siege to his
last stronghold--the position that there is a distinction in kind
between the mental faculties of man and those of brutes; and that, in
consequence of this distinction in kind, no gradual progress from
the mental faculties of the one to those of the other can have taken
place.
The Quarterly Reviewer entrenches himself within formidable-looking
psychological outworks, and there is no getting at him without
attacking them one by one.
He begins by laying down the following proposition: "'Sensation' is
not 'thought,' and no amount of the former would constitute the most
rudimentary condition of the latter, though sensations supply the
conditions for the existence of 'thought' or 'knowledge'" (p. 67).
This proposition is true, or not, according to the sense in which the
word "thought" is employed. Thought is not uncommonly used in a sense
co-extensive with consciousness, and, especially, with those states
of consciousness we call memory. If I recall the impression made by a
colour or an odour, and distinctly remember blueness or muskiness, I
may say with perfect propriety that I "think of" blue or musk; and,
so long as the thought lasts, it is simply a faint reproduction of the
state of consciousness to which I gave the name in question, when it
first became known to me as a sensation.
Now, if that faint reproduction of a sensation, which we call the
memory of it, is properly termed a thought, it seems to me to be
a somewhat forced, proceeding to draw a hard and fast line of
demarcation between thoughts and sensations. If sensations are
not rudimentary thoughts, it may be said that some thoughts are
rudimentary sensations. No amount of sound constitutes an echo, but
for all that no one would pretend that an echo is something of totally
different nature from a sound. Again, nothing can be looser, or more
inaccurate, than the assertion that "sensations supply the conditions
for the existence of thought or knowledge." If this implies that
sensations supply the conditions for the existence of our memory of
sensations or of our thoughts about sensations, it is a truism which
it is hardly worth while to state so solemnly. If it implies that
sensations supply anything else, it is obviously erroneous. And if it
means, as the context would seem to show it does, that sensations are
the subject-matter of all thought or knowledge, then it is no less
contrary to fact, inasmuch as our emotions, which constitute a
large part of the subject-matter of thought or of knowledge, are not
sensations.
More eccentric still is the Quarterly Reviewer's next piece of
psychology.
"Altogether, we may clearly distinguish at least six kinds of
action to which the nervous system ministers:--
"I. That in which impressions received result in appropriate
movements without the intervention of sensation or thought, as
in the cases of injury above given.--This is the reflex action
of the nervous system.
"II. That in which stimuli from without result in sensations
through the agency of which their due effects are wrought
out--Sensation.
"III. That in which impressions received result in
sensations which give rise to the observation of sensible
objects.--Sensible perception.
"IV. That in which sensations and perceptions continue to
coalesce, agglutinate, and combine in more or less complex
aggregations, according to the laws of the association of
sensible perceptions.--Association.
"The above four groups contain only indeliberate operations,
consisting, as they do at the best, but of mere _presentative_
sensible ideas in no way implying any reflective or
_representative_ faculty. Such actions minister to and form
_Instinct_. Besides these, we may distinguish two other kinds
of mental action, namely:--
"V. That in which sensations and sensible perceptions are
reflected on by thought, and recognized as our own, and
we ourselves recognized by ourselves as affected and
perceiving.--Self-consciousness.
"VI. That in which we reflect upon our sensations or
perceptions, and ask what they are, and why they are.--Reason.
"These two latter kinds of action are deliberate operations,
performed, as they are, by means of representative ideas
implying the use of a _reflective representative_ faculty.
Such actions distinguish the _intellect_ or rational faculty.
Now, we assert that possession in perfection of all the first
four _(presentative)_ kinds of action by no means implies
the possession of the last two _(representative)_ kinds.
All persons, we think, must admit the truth of the following
proposition:--
"Two faculties are distinct, not in degree but _in kind_,
if we may possess the one in perfection without that fact
implying that we possess the other also. Still more will
this be the case if the two faculties tend to increase in
an inverse ratio. Yet this is the distinction between the
_instinctive_ and the _intellectual_ parts of man's nature.
"As to animals, we fully admit that they may possess all the
first four groups of actions--that they may have, so to speak,
mental images of sensible objects combined in all degrees of
complexity, as governed by the laws of association. We deny to
them, on the other hand, the possession of the last two
kinds of mental action. We deny them, that is, the power of
reflecting on their own existence, or of inquiring into the
nature of objects and their causes. We deny that they know
that they know or know themselves in knowing. In other words,
we deny them _reason_. The possession of the presentative
faculty, as above explained, in no way implies that of the
reflective faculty; nor does any amount of direct operation
imply the power of asking the reflective question before
mentioned, as to 'what' and 'why.'" _(Loc. cit_. pp. 67, 68.)
Sundry points are worthy of notice in this remarkable account of the
intellectual powers. In the first place the Reviewer ignores emotion
and volition, though they are no inconsiderable "kinds of action to
which the nervous system ministers," and memory has a place in his
classification only by implication. Secondly, we are told that the
second "kind of action to which the nervous system ministers" is "that
in which stimuli from without result in sensations through the agency
of which their due effects are wrought out.--Sensation." Does this
really mean that, in the writer's opinion, "sensation" is the "agent"
by which the "due effect" of the stimulus, which gives rise to
sensation, is "wrought out"? Suppose somebody runs a pin into me. The
"due effect" of that particular stimulus will probably be threefold;
namely, a sensation of pain, a start, and an interjectional expletive.
Does the Quarterly Reviewer really think that the "sensation" is the
"agent" by which the other two phenomena are wrought out?
But these matters are of little moment to anyone but the Reviewer
and those persons who may incautiously take their physiology, or
psychology, from him. The really interesting point is this, that when
he fully admits that animals "may possess all the first four groups
of actions," he grants all that is necessary for the purposes of
the evolutionist. For he hereby admits that in animals "impressions
received result in sensations which give rise to the observation
of sensible objects," and that they have what he calls "sensible
perception." Nor was it possible to help the admission; for we have
as much reason to ascribe to animals, as we have to attribute to our
fellow-men, the power, not only of perceiving external objects as
external, and thus practically recognizing the difference between the
self and the not-self; but that of distinguishing between like
and unlike, and between simultaneous and successive things. When a
gamekeeper goes out coursing with a greyhound in leash, and a hare
crosses the field of vision, he becomes the subject of those states
of consciousness we call visual sensation, and that is all he receives
from without. Sensation, as such, tells him nothing whatever about
the cause of these states of consciousness; but the thinking faculty
instantly goes to work upon the raw material of sensation furnished to
it through the eye, and gives rise to a train of thoughts. First comes
the thought that there is an object at a certain distance; then arises
another thought--the perception of the likeness between the states of
consciousness awakened by this object to those presented by memory,
as, on some former occasion, called up by a hare; this is succeeded
by another thought of the nature of an emotion--namely, the desire
to possess the hare; then follows a longer or shorter train of other
thoughts, which end in a volition and an act--the loosing of the
greyhound from the leash. These several thoughts are the concomitants
of a process which goes on in the nervous system of the man. Unless
the nerve-elements of the retina, of the optic nerve, of the brain, of
the spinal chord, and of the nerves of the arms went through certain
physical changes in due order and correlation, the various states
of consciousness which have been enumerated would not make their
appearance. So that in this, as in all other intellectual operations,
we have to distinguish two sets of successive changes--one in the
physical basis of consciousness, and the other in consciousness
itself; one set which may, and doubtless will, in course of time,
be followed through all their complexities by the anatomist and the
physicist, and one of which only the man himself can have immediate
knowledge.
As it is very necessary to keep up a clear distinction between
these two processes, let the one be called _neurosis_, and the other
_psychosis_. When the gamekeeper was first trained to his work, every
step in the process of neurosis was accompanied by a corresponding
step in that of psychosis, or nearly so. He was conscious of seeing
something, conscious of making sure it was a hare, conscious of
desiring to catch it, and therefore to loose the greyhound at the
right time, conscious of the acts by which he let the dog out of the
leash. But with practice, though the various steps of the neurosis
remain--for otherwise the impression on the retina would not result
in the loosing of the dog--the great majority of the steps of the
psychosis vanish, and the loosing of the dog follows unconsciously, or
as we say, without thinking about it, upon the sight of the hare.
No one will deny that the series of acts which originally intervened
between the sensation and the letting go of the dog were, in the
strictest sense, intellectual and rational operations. Do they cease
to be so when the man ceases to be conscious of them? That depends
upon what is the essence and what the accident of those operations,
which, taken together, constitute ratiocination.
Now ratiocination is resolvable into predication, and predication
consists in marking, in some way, the existence, the co-existence,
the succession, the likeness and unlikeness, of things or their ideas.
Whatever does this, reasons; and if a machine produces the effects of
reason, I see no more ground for denying to it the reasoning power,
because it is unconscious, than I see for refusing to Mr. Babbage's
engine the title of a calculating machine on the same grounds.
Thus it seems to me that a gamekeeper reasons, whether he is conscious
or unconscious, whether his reasoning is carried on by neurosis alone,
or whether it involves more or less psychosis. And if this is true
of the gamekeeper, it is also true of the greyhound. The essential
resemblances in all points of structure and function, so far as they
can be studied, between the nervous system of the man and that of the
dog, leave no reasonable doubt that the processes which go on in the
one are just like those which take place in the other. In the dog,
there can be no doubt that the nervous matter which lies between
the retina and the muscles undergoes a series of changes, precisely
analogous to those which, in the man, give rise to sensation, a train
of thought, and volition.
Whether this neurosis is accompanied by such psychosis as ours, it is
impossible to say; but those who deny that the nervous changes, which,
in the dog, correspond with those which underlie thought in a man, are
accompanied by consciousness, are equally bound to maintain that those
nervous changes in the dog, which correspond with those which underlie
sensation in a man, are also unaccompanied by consciousness. In other
words, if there is no ground for believing that a dog thinks, neither
is there any for believing that he feels.
As is well known, Descartes boldly faced this dilemma, and
maintained that all animals were mere machines and entirely devoid of
consciousness. But he did not deny, nor can anyone deny, that in this
case they are reasoning machines, capable of performing all those
operations which are performed by the nervous system of man when he
reasons. For even supposing that in man, and in man only, psychosis is
superadded to neurosis--the neurosis which is common to both man
and animal gives their reasoning processes a fundamental unity.
But Descartes's position is open to very serious objections, if the
evidence that animals feel is insufficient to prove that they really
do so. What is the value of the evidence which leads one to believe
that one's fellow-man feels? The only evidence in this argument of
analogy, is the similarity of his structure and of his actions to
one's own. And if that is good enough to prove that one's fellow-man
feels, surely it is good enough to prove that an ape feels. For the
differences of structure and function between men and apes are utterly
insufficient to warrant the assumption, that while men have those
states of consciousness we call sensations, apes have nothing of the
kind. Moreover, we have as good evidence that apes are capable of
emotion and volition as we have that men other than ourselves are. But
if apes possess three out of the four kinds of states of consciousness
which we discover in ourselves, what possible reason is there for
denying them the fourth? If they are capable of sensation, emotion,
and volition, why are they to be denied thought (in the sense of
predication)?
No answer has ever been given to these questions. And as the law of
continuity is as much opposed, as is the common sense of mankind, to
the notion that all animals are unconscious machines, it may safely be
assumed that no sufficient answer ever will be given to them.
There is every reason to believe that consciousness is a function
of nervous matter, when, that nervous matter has attained a certain
degree of organization, just as we know the other "actions to which
the nervous system ministers," such as reflex action and the like, to
be. As I have ventured to state my view of the matter elsewhere, "our
thoughts are the expression of molecular changes in that matter of
life which is the source of our other vital phenomena."
Mr. Wallace objects to this statement in the following terms:--
"Not having been able to find any clue in Professor Huxley's
writings to the steps by which he passes from those vital
phenomena, which consist only, in their last analysis, of
movements by particles of matter, to those other phenomena
which we term thought, sensation, or consciousness; but,
knowing that so positive an expression of opinion from him
will have great weight with many persons, I shall endeavour
to show, with as much brevity as is compatible with clearness,
that this theory is not only incapable of proof, but is also,
as it appears to me, inconsistent with accurate conceptions of
molecular physics."
With all respect for Mr. Wallace, it appears to me that his remarks
are entirely beside the question. I really know nothing whatever, and
never hope to know anything, of the steps by which the passage from
molecular movement to states of consciousness is effected; and I
entirely agree with the sense of the passage which he quotes from
Professor Tyndall, apparently imagining that it is in opposition to
the view I hold.
All that I have to say is, that, in my belief, consciousness and
molecular action are capable of being expressed by one another, just
as heat and mechanical action are capable of being expressed in terms
of one another. Whether we shall ever be able to express consciousness
in foot-pounds, or not, is more than I will venture to say; but
that there is evidence of the existence of some correlation between
mechanical motion and consciousness, is as plain as anything can be.
Suppose the poles of an electric battery to be connected by a platinum
wire. A certain intensity of the current gives rise in the mind of a
bystander to that state of consciousness we call a "dull red light"--a
little greater intensity to another which we call a "bright red
light;" increase the intensity, and the light becomes white; and,
finally, it dazzles, and a new state of consciousness arises, which we
term pain. Given the same wire and the same nervous apparatus, and the
amount of electric force required to give rise to these several states
of consciousness will be the same, however often the experiment
is repeated. And as the electric force, the light-waves, and the
nerve-vibrations caused by the impact of the light-waves on the
retina, are all expressions of the molecular changes which are taking
place in the elements of the battery; so consciousness is, in the same
sense, an expression of the molecular changes which take place in that
nervous matter, which is the organ of consciousness.
And, since this, and any number of similar examples that may be
required, prove that one form of consciousness, at any rate, is, in
the strictest sense, the expression of molecular change, it really
is not worth while to pursue the inquiry, whether a fact so easily
established is consistent with any particular system of molecular
physics or not.
Mr. Wallace, in fact, appears to me to have mixed up two very distinct
propositions: the one, the indisputable truth that consciousness is
correlated with molecular changes in the organ of consciousness;
the other, that the nature of that correlation is known, or can be
conceived, which is quite another matter. Mr. Wallace, presumably,
believes in that correlation of phenomena which we call cause and
effect as firmly as I do. But if he has ever been able to form the
faintest notion how a cause gives rise to its effect, all I can say is
that I envy him. Take the simplest case imaginable--suppose a ball in
motion to impinge upon another ball at rest. I know very well, as a
matter of fact, that the ball in motion will communicate some of its
motion to the ball at rest, and that the motion of the two balls after
collision is precisely correlated with the masses of both balls and
the amount of motion of the first. But how does this come about? In
what manner can we conceive that the _vis viva_ of the first ball
passes into the second? I confess I can no more form any conception
of what happens in this case, than I can of what takes place when the
motion of particles of my nervous matter, caused by the impact of a
similar ball, gives rise to the state of consciousness I call pain. In
ultimate analysis everything is incomprehensible, and the whole object
of science is simply to reduce the fundamental incomprehensibilities
to the smallest possible number.
But to return to the Quarterly Reviewer. He admits that animals
have "mental images of sensible objects, combined in all degrees of
complexity, as governed by the laws of association." Presumably, by
this confused and imperfect statement the Reviewer means to admit
more than the words imply. For mental images of sensible objects,
even though "combined in all degrees of complexity," are, and can be,
nothing more than mental images of sensible objects. But judgments,
emotions, and volitions cannot by any possibility be included under
the head of "mental images of sensible objects."
If the greyhound had no better mental endowment than the Reviewer
allows him, he might have the "mental image" of the "sensible
object"--the hare--and that might be combined with the mental images
of other sensible objects, to any degree of complexity, but he would
have no power of judging it to be at a certain distance from him; no
power of perceiving its similarity to his memory of a hare; and no
desire to get at it. Consequently he would stand stock still, and the
noble art of coursing would have no existence. On the other hand,
as that art is largely practised, it follows that greyhounds alone
possess a number of mental powers, the existence of which, in any
animal, is absolutely denied by the Quarterly Reviewer.
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