Knowledge
of Freedom
CHAPTER FOUR
The
World as Percept
THROUGH
thinking, concepts and ideas arise.
What a concept is cannot be expressed in words. Words can do no
more than draw our attention to the fact that we have concepts.
When someone sees a tree, his thinking reacts to his observation,
an ideal element is added to the object, and he considers the
object and the ideal counterpart as belonging together.
When the object disappears from his field of observation,
only the ideal counterpart of it remains. This latter is the
concept of the object. The more our range of experience is
widened, the greater becomes the sum of our concepts. But
concepts certainly do not stand isolated from one another.
They combine to form a systematically ordered whole. The
concept “organism”, for instance, links up with those of
“orderly development” and “growth”. Other concepts
which are based on single objects merge together into a
unity. All concepts I may form of lions merge into the
collective concept “lion”. In this way all the separate concepts
combine to form a closed conceptual system in which
each has its special place. Ideas do not differ qualitatively
from concepts.
They are but fuller, more saturated, more
comprehensive concepts. I must attach special importance
to the necessity of bearing in mind, here, that I make
thinking my starting point,
and not concepts and ideas which
are first gained by means of thinking. For these latter already
presuppose thinking. My remarks regarding the self-supporting
and self-determined nature of thinking cannot,
therefore, be simply transferred to concepts. (I make special
mention of this, because it is here that I differ from
Hegel,
who regards the concept as something primary and original.)
Concepts cannot be gained through observation. This
follows from the simple fact that the growing human being
only slowly and gradually forms the concepts corresponding
to the objects which surround him. Concepts are added to
observation.
A philosopher widely read at the present day —
Herbert Spencer
— describes the mental process which we carry out
with respect to observation as follows:
If, when walking through the fields some day in September,
you hear a rustle a few yards in advance, and on observing the
ditch-side where it occurs, see the herbage agitated, you will
probably turn towards the spot to learn by what this sound and
motion are produced. As you approach there flutters into the
ditch a partridge; on seeing which your curiosity is satisfied —
you have what you call an explanation of the appearances. The
explanation, mark, amounts to this; that whereas throughout
life you have had countless experiences of disturbance among
small stationary bodies, accompanying the movement of other
bodies among them, and have generalized the relation between
such disturbances and such movements, you consider this
particular disturbance explained on finding it to present an
instance of the like relation.
(see fn 1)
A closer analysis shows matters to stand very differently
from the way described above. When I hear a noise, I first
look for the concept which fits this observation. It is this
concept which first leads me beyond the mere noise. If one
thinks no further, one simply hears the noise and is content
to leave it at that. But my reflecting makes it clear to me that
I have to regard the noise as an effect. Therefore not until I
have connected the concept of effect with the perception of
the noise, do I feel the need to go beyond the solitary
observation and look for the cause. The concept of effect
calls up that of cause, and my next step is to look for the
object which is being the cause, which I find in the shape of
the partridge. But these concepts, cause and effect, I can
never gain through mere observation, however many
instances the observation may cover. Observation evokes
thinking, and it is thinking that first shows me how to link
one separate experience to another.
If one demands of a “strictly objective science” that it
should take its content from observation alone, then one
must at the same time demand that it should forego all
thinking. For thinking, by its very nature, goes beyond what
is observed.
We must now pass from thinking to the being that thinks;
for it is through the thinker that thinking is combined with
observation. Human consciousness is the stage upon which
concept and observation meet and become linked to one
another. In saying this we have in fact characterized this
(human) consciousness. It is the mediator between thinking
and observation. In as far as we observe a thing it appears to
us as given; in as far as we think, we appear to ourselves as
being active. We regard the thing as object and ourselves as
thinking subject. Because we direct our thinking upon our
observation, we have consciousness of objects; because we
direct it upon ourselves, we have consciousness of ourselves,
or self-consciousness. Human consciousness must of necessity
be at the same time self-consciousness because it is a
consciousness which thinks. For when thinking contemplates its
own activity, it makes its own essential being, as subject,
into a thing, as object.
It must, however, not be overlooked that only with the
help of thinking am I able to determine myself as subject
and contrast myself with objects. Therefore thinking must
never be regarded as a merely subjective activity. Thinking
lies beyond subject and object. It produces these two concepts
just as it produces all others. When, therefore, I, as thinking
subject, refer a concept to an object, we must not regard this
reference as something purely subjective. It is not the subject
that makes the reference, but thinking. The subject does not
think because it is a subject; rather it appears to itself as
subject because it can think. The activity exercised by man
as a thinking being is thus not merely subjective. Rather is it
something neither subjective nor objective, that transcends
both these concepts. I ought never to say that my individual
subject thinks, but much more that my individual subject
lives by the grace of thinking. Thinking is thus an element
which leads me out beyond myself and connects me with
the objects. But at the same time it separates me from
them, inasmuch as it sets me, as subject, over against
them.
It is just this which constitutes the double nature of man.
He thinks, and thereby embraces both himself and the rest of
the world. But at the same time it is by means of thinking
that he determines himself as an individual confronting the
things.
We must next ask ourselves how that other element, which
we have so far simply called the object of observation and
which meets the thinking in our consciousness, comes into
our consciousness at all.
In order to answer this question we must eliminate from
our field of observation everything that has been imported
by thinking. For at any moment the content of our consciousness
will already be interwoven with concepts in the most varied ways.
We must imagine that a being with fully developed human
intelligence originates out of nothing and confronts the
world. What it would be aware of, before it sets its thinking
in motion, would be the pure content of observation. The
world would then appear to this being as nothing but a mere
disconnected aggregate of objects of sensation: colors,
sounds, sensations of pressure, of warmth, of taste and smell;
also feelings of pleasure and pain. This aggregate is the
content of pure, unthinking observation. Over against it
stands thinking, ready to begin its activity as soon as a point
of attack presents itself. Experience shows at once that this
does happen. Thinking is able to draw threads from one
element of observation to another. It links definite concepts
with these elements and thereby establishes a relationship
between them. We have already seen how a noise which we
hear becomes connected with another observation by our
identifying the former as the effect of the latter.
If now we recollect that the activity of thinking is on no
account to be considered as merely subjective, then we shall
also not be tempted to believe that the relationships thus
established by thinking have merely subjective validity.
Our next task is to discover by means of thoughtful
reflection what relation the immediately given content of
observation mentioned above has to the conscious subject.
The ambiguity of current speech makes it necessary for
me to come to an agreement with my readers concerning the
use of a word which I shall have to employ in what follows.
I shall apply the word “percept” to the immediate objects
of sensation enumerated above, in so far as the conscious
subject apprehends them through observation. It is, then,
not the process of observation but the object of observation
which I call the “percept”.
I do not choose the term “sensation”, since this has a
definite meaning in physiology which is narrower than that
of my concept of “percept”. I can speak of a feeling in
myself (emotion) as percept, but not as sensation in the
physiological sense of the term. Even my feeling becomes
known to me by becoming a percept for me. And the way in
which we gain knowledge of our thinking through observation
is such that thinking too, in its first appearance for our
consciousness, may be called a percept.
The naïve man regards his percepts, such as they appear
to his immediate apprehension, as things having an existence
wholly independent of him. When he sees a tree he believes
in the first instance that it stands in the form which he sees,
with the colors of its various parts, and so on, there on the
spot towards which his gaze is directed. When the same
man sees the sun in the morning appear as a disc on the
horizon, and follows the course of this disc, he believes that
all this actually exists and happens just as he observes it. To
this belief he clings until he meets with further percepts
which contradict his former ones. The child who as yet has
no experience of distance grasps at the moon, and only
corrects its picture of the reality, based on first impressions,
when a second percept contradicts the first. Every extension
of the circle of my percepts compels me to correct my picture
of the world. We see this in everyday life, as well as in the
spiritual development of mankind. The picture which the
ancients made for themselves of the relation of the earth to
the sun and other heavenly bodies had to be replaced by
another when Copernicus found that it was not in accordance
with some percepts, which in those early days were unknown.
A man who had been born blind said, when operated on by
Dr. Franz,
that the picture of the size of objects which he
had formed by his sense of touch before his operation, was a
very different one. He had to correct his tactual percepts by
his visual percepts.
How is it that we are compelled to make these continual
corrections to our observations?
A simple reflection gives the answer to this question. When
I stand at one end of an avenue, the trees at the other end,
away from me, seem smaller and nearer together than those
where I stand. My percept-picture changes when I change
the place from which I am looking. Therefore the form in
which it presents itself to me is dependent on a condition
which is due not to the object but to me, the perceiver. It is
all the same to the avenue wherever I stand. But the picture
I have of it depends essentially on just this viewpoint. In the
same way, it makes no difference to the sun and the planetary
system that human beings happen to look at them from the
earth; but the percept-picture of the heavens presented to
them is determined by the fact that they inhabit the earth.
This dependence of our percept-picture on our place of
observation is the easiest one to understand. The matter
becomes more difficult when we realize how our world of
percepts is dependent on our bodily and spiritual organization.
The physicist shows us that within the space in which
we hear a sound there are vibrations of the air, and also that
the body in which we seek the origin of the sound exhibits a
vibrating movement of its parts. We perceive this movement
as sound only if we have a normally constructed ear. Without
this the world would be for ever silent for us. Physiology
tells us that there are people who perceive nothing of the
magnificent splendor of color which surrounds us. Their
percept-picture has only degrees of light and dark. Others
are blind only to one color, for example, red. Their world
picture lacks this hue, and hence it is actually a different one
from that of the average man. I should like to call the
dependence of my percept-picture on my place of observation,
“mathematical”, and its dependence on my organization,
“qualitative”. The former determines the proportions
of size and mutual distances of my percepts, the latter their
quality. The fact that I see a red surface as red — this
qualitative determination — depends on the organization of
my eye.
My percept-pictures, then, are in the first instance subjective.
The recognition of the subjective character of our
percepts may easily lead us to doubt whether there is any
objective basis for them at all. When we realize that a
percept, for example that of a red color or of a certain tone,
is not possible without a specific structure of our organism,
we may easily be led to believe that it has no permanency
apart from our subjective organization and that, were it not
for our act of perceiving it as an object, it would not exist
in any sense. The classical representative of this view is
George Berkeley,
who held that from the moment we realize
the importance of the subject for perception, we are no
longer able to believe in the existence of a world without a
conscious Spirit.
Some truths there are so near and obvious to the mind that
man need only open his eyes to see them. Such I take this
important one to be, to wit, that all the choir of heaven and
furniture of the earth, in a word, all those bodies which compose
the mighty frame of the world, have not any subsistence
without a mind, that their being is to be perceived or known;
that, consequently, so long as they are not actually perceived
by me, or do not exist in my mind or that of any other created
spirit, they must either have no existence at all, or else subsist
in the mind of some Eternal Spirit.
(see fn 2)
On this view, when we take away the fact of its being
perceived, nothing remains of the percept. There is no
color when none is seen, no sound when none is heard.
Extension, form, and motion exist as little as color and
sound apart from the act of perception. Nowhere do we see
bare extension or shape, but these are always bound up with
color or some other quality unquestionably dependent upon
our subjectivity. If these latter disappear when we cease to
perceive them, then the former, being bound up with them,
must disappear likewise.
To the objection that there must be things that exist apart
from consciousness and to which the conscious percept-pictures
are similar, even though figure, color, sound, and
so on, have no existence except within the act of perceiving,
the above view would answer that a color can be similar
only to a color, a figure only to a figure. Our percepts can
be similar only to our percepts and to nothing else. Even
what we call an object is nothing but a collection of percepts
which are connected in a particular way. If I strip a table of
its shape, extension, color, etc. — in short, of all that is
merely my percept — then nothing remains over. This view,
followed up logically, leads to the assertion that the objects
of my perceptions exist only through me, and indeed only
in as far as, and as long as, I perceive them; they disappear
with my perceiving and have no meaning apart from it.
Apart from my percepts, I know of no objects and cannot
know of any.
No objection
can be made to this assertion as long as I am
merely referring to the general fact that the percept is partly
determined by the organization of myself as subject. The
matter would appear very different if we were in a position
to say just what part is played by our perceiving in the
bringing forth of a percept. We should then know what
happens to a percept while it is being perceived, and we
should also be able to determine what character it must
already possess before it comes to be perceived.
This leads us to turn our attention from the object of
perception to the subject of perception. I perceive not only
other things, but also myself. The percept of myself contains,
to begin with, the fact that I am the stable element in contrast
to the continual coming and going of the percept-pictures.
The percept of my “I” can always come up in my
consciousness while I am having other percepts. When I am
absorbed in the perception of a given object I am for the
time being aware only of this object. To this the percept of
my self can be added. I am then conscious not only of the
object but also of my own personality which confronts the
object and observes it. I do not merely see a tree, but I also
know that it is I who am seeing it. I know, moreover, that
something happens in me while I am observing the tree.
When the tree disappears from my field of vision, an after-effect
of this process remains in my consciousness — a picture
of the tree. This picture has become associated with my self
during my observation. My self has become enriched; its
content has absorbed a new element. This element I call my
mental picture of the tree. I should never have occasion to
speak of mental pictures did I not experience them in the
percept of my own self. Percepts would come and go; I
should let them slip by. Only because I perceive my self,
and observe that with each percept the content of my self,
too, is changed, am I compelled to connect the observation
of the object with the changes in my own condition, and to
speak of my mental picture.
I perceive the mental picture in my self in the same sense
as I perceive color, sound, etc., in other objects. I am now
also able to distinguish these other objects that confront me,
by calling them the outer world, whereas the content of my
percept of my self I call my inner world. The failure to
recognize the true relationship between mental picture and
object has led to the greatest misunderstandings in modern
philosophy. The perception of a change in me, the modification
my self undergoes, has been thrust into the foreground,
while the object which causes this modification is lost sight
of altogether. It has been said that we perceive not objects
but only our mental pictures. I know, so it is said, nothing
of the table in itself, which is the object of my observation,
but only of the change which occurs within me while I am
perceiving the table. This view should not be confused with
the Berkeleyan theory mentioned above. Berkeley maintains
the subjective nature of the content of my percepts, but he
does not say that my knowledge is limited to my mental
pictures. He limits my knowledge to my mental pictures
because, in his opinion, there are no objects apart from
mental picturing. What I take to be a table no longer exists,
according to Berkeley, when I cease to look at it. This is why
Berkeley holds that my percepts arise directly through the
omnipotence of God. I see a table because God calls up this
percept in me. For Berkeley, therefore, there are no real
beings other than God and human spirits. What we call the
“world” exists only in these spirits. What the naïve
man calls the outer world, or corporeal nature, is for
Berkeley
non-existent. This theory is confronted by the now predominant
Kantian view which limits our knowledge of the world to
our mental pictures, not because it is convinced that things
cannot exist beyond these mental pictures, but because it
believes us to be so organized that we can experience only
the changes of our own selves, but not the things-in-themselves
that cause these changes. This view concludes from
the fact that I know only my mental pictures, not that there
is no reality independent of them, but only that the subject
cannot directly assimilate such reality. The subject can
merely, “through the medium of its subjective thoughts,
imagine it, invent it, think it, cognize it, or perhaps
even fail to cognize it.”
(see fn 3) This (Kantian) conception
believes it gives expression to something absolutely certain,
something which is immediately evident, requiring no
proof.
The first fundamental proposition which the philosopher
must bring to clear consciousness is the recognition that our
knowledge, to begin with, is limited to our mental pictures.
Our mental pictures are the only things that we know directly,
experience directly; and just because we have direct experience
of them, even the most radical doubt cannot rob us of our
knowledge of them. On the other hand, the knowledge which
goes beyond my mental pictures — taking mental pictures here
in the widest possible sense, so as to include all psychical
processes — is not proof against doubt. Hence, at the very
beginning of all philosophizing we must explicitly set down all
knowledge which goes beyond mental pictures as being open
to doubt.
These are the opening sentences of Volkelt's book on
Immanuel Kant's
Theory of Knowledge.
What is here put
forward as an immediate and self-evident truth is in reality
the result of a thought operation which runs as follows: The
naïve man believes that things, just as we perceive them,
exist also outside our consciousness. Physics, physiology, and
psychology, however, seem to teach us that for our percepts
our organization is necessary, and that therefore we cannot
know anything about external objects except what our
organization transmits to us. Our percepts are thus modifications
of our organization, not things-in-themselves. This
train of thought has in fact been characterized by
Eduard von Hartmann
as the one which must lead to the conviction
that we can have direct knowledge only of our mental
pictures.
(see fn 4)
Because, outside our organism, we find vibrations
of physical bodies and of the air which are perceived by us as
sound, it is concluded that what we call sound is nothing
more than a subjective reaction of our organism to these
motions in the external world. Similarly, it is concluded that
color and warmth are merely modifications of our organism.
And, further, these two kinds of percepts are held to be
produced in us through processes in the external world
which are utterly different from what we experience as
warmth or as color. When these processes stimulate
the nerves in my skin, I have the subjective percept of
warmth; when they stimulate the optic nerve, I perceive
light and color. Light, color, and warmth, then, are the
responses of my sensory nerves to external stimuli. Even
the sense of touch reveals to me, not the objects of the outer
world, but only states of my own body. In the sense of
modern physics one could somehow think that bodies
consist of infinitely small particles called molecules, and that
these molecules are not in direct contact, but are at certain
distances from one another. Between them, therefore, is
empty space. Across this space they act on one another by
forces of attraction and repulsion. If I put my hand on a
body, the molecules of my hand by no means touch those of
the body directly, but there remains a certain distance between
body and hand, and what I experience as the body's resistance
is nothing but the effect of the force of repulsion which
its molecules exert on my hand. I am absolutely external
to the body and perceive only its effects on my organism.
In amplification of this discussion, there is the theory of
the so-called Specific Nerve Energies, advanced by
J. Müller
(1801–1858). It asserts that each sense has the
peculiarity that it responds to all external stimuli in one
particular way only. If the optic nerve is stimulated, perception
of light results, irrespective of whether the stimulation
is due to what we call light, or whether mechanical pressure
or an electric current works upon the nerve. On the other
hand, the same external stimulus applied to different senses
gives rise to different percepts. The conclusion from these
facts seems to be that our senses can transmit only what
occurs in themselves, but nothing of the external world.
They determine our percepts, each according to its own
nature.
Physiology shows that there can be no direct knowledge
even of the effects which objects produce on our sense
organs. Through following up the processes which occur in
our own bodies, the physiologist finds that, even in the sense
organs, the effects of the external movement are transformed
in the most manifold ways. We can see this most
clearly in the case of eye and ear. Both are very complicated
organs which modify the external stimulus considerably
before they conduct it to the corresponding nerve. From the
peripheral end of the nerve the already modified stimulus is
then conducted to the brain. Only now can the central organs
be stimulated. Therefore it is concluded that the external
process undergoes a series of transformations before it
reaches consciousness. What goes on in the brain is connected
by so many intermediate links with the external
process, that any similarity to the latter is out of the question.
What the brain ultimately transmits to the soul is neither
external processes, nor processes in the sense organs, but
only such as occur in the brain. But even these are not
perceived directly by the soul. What we finally have in
consciousness are not brain processes at all, but sensations.
My sensation of red has absolutely no similarity to the
process which occurs in the brain when I sense red. The
redness, again, only appears as an effect in the soul, and the
brain process is merely its cause. This is why Hartmann says,
“What the subject perceives, therefore, are always only
modifications of his own psychical states and nothing else.”
(see fn 5)
When I have the sensations, however, they are as yet very
far from being grouped into what I perceive as “things”.
Only single sensations can be transmitted to me by the
brain. The sensations of hardness and softness are transmitted
to me by the sense of touch, those of color and light
by the sense of sight. Yet all these are to be found united in
one and the same object. This unification, therefore, can
only be brought about by the soul itself; that is, the soul
combines the separate sensations, mediated through the
brain, into bodies. My brain conveys to me singly, and by
widely different paths, the visual, tactile, and auditory
sensations which the soul then combines into the mental
picture of a trumpet. It is just this very last link in a process
(the mental picture of the trumpet) which for my consciousness
is the very first thing that is given. In it nothing can any
longer be found of what exists outside me and originally
made an impression on my senses. The external object has
been entirely lost on the way to the brain and through the
brain to the soul.
It would be hard to find in the history of human culture
another edifice of thought which has been built up with
greater ingenuity, and which yet, on closer analysis, collapses
into nothing. Let us look a little closer at the way it
has been constructed. One starts with what is given in naïve
consciousness, with the thing as perceived. Then one shows
that none of the qualities which we find in this thing would
exist for us had we no sense organs. No eye — no color.
Therefore the color is not yet present in that which affects
the eye. It arises first through the interaction of the eye and
the object. The latter is, therefore, colorless. But neither
is the color in the eye, for in the eye there is only a chemical
or physical process which is first conducted by the optic
nerve to the brain, and there initiates another process. Even
this is not yet the color. That is only produced in the soul
by means of the brain process. Even then it does not yet
enter my consciousness, but is first transferred by the soul to
a body in the external world. There, upon this body, I
finally believe myself to perceive it. We have traveled in a
complete circle. We became conscious of a colored body.
That is the first thing. Here the thought operation starts. If
I had no eye, the body would be, for me, colorless. I
cannot therefore attribute the color to the body. I start on
the search for it. I look for it in the eye — in vain; in the
nerve — in vain; in the brain — in vain once more; in the
soul — here I find it indeed, but not attached to the body. I
find the colored body again only on returning to my starting
point. The circle is completed. I believe that I am cognizing
as a product of my soul that which the naïve man regards as
existing outside him, in space.
As long as one stops here everything seems to fit beautifully.
But we must go over the whole thing again from the
beginning. Hitherto I have been dealing with something —
the external percept — of which, from my naïve standpoint,
I have had until now a totally wrong conception. I thought
that the percept, just as I perceive it, had objective existence.
But now I observe that it disappears together with my
mental picture, that it is only a modification of my inner state
of soul. Have I, then, any right at all to start from it in my
arguments? Can I say of it that it acts on my soul? I must
henceforth treat the table, of which formerly I believed that
it acted on me and produced a mental picture of itself in me,
as itself a mental picture. But from this it follows logically
that my sense organs and the processes in them are also
merely subjective. I have no right to speak of a real eye but
only of my mental picture of the eye. Exactly the same is
true of the nerve paths, and the brain process, and no less of
the process in the soul itself, through which things are
supposed to be built up out of the chaos of manifold sensations.
If, assuming the truth of the first circle of argumentation,
I run through the steps of my act of cognition once
more, the latter reveals itself as a tissue of mental pictures
which, as such, cannot act on one another. I cannot say that
my mental picture of the object acts on my mental picture
of the eye, and that from this interaction my mental picture
of color results. Nor is it necessary that I should say this.
For as soon as I see clearly that my sense organs and their
activity, my nerve and soul processes, can also be known to
me only through perception, the train of thought which I
have outlined reveals itself in its full absurdity. It is quite
true that I can have no percept without the corresponding
sense organ. But just as little can I be aware of a sense organ
without perception. From the percept of a table I can pass to
the eye which sees it, or the nerves in the skin which touch
it, but what takes place in these I can, in turn, learn only
from perception. And then I soon notice that there is no
trace of similarity between the process which takes place in
the eye and the color which I perceive. I cannot eliminate
my color percept by pointing to the process which takes
place in the eye during this perception. No more can I
rediscover the color in the nerve or brain processes. I only
add new percepts, localized within the organism, to the first
percept, which the naïve man localizes outside his organism.
I merely pass from one percept to another.
Moreover there is a gap in the whole argument. I can
follow the processes in my organism up to those in my
brain, even though my assumptions become more and more
hypothetical as I approach the central processes of the
brain. The path of external observation ceases with the
process in my brain, more particularly with the process
which I should observe if I could deal with the brain using
the instruments and methods of physics and chemistry. The
path of inner observation begins with the sensation, and
continues up to the building of things out of the material of
sensation. At the point of transition from brain process to
sensation, the path of observation is interrupted.
The way of thinking here described, known as critical
idealism, in contrast to the standpoint of naïve consciousness
known as naïve realism, makes the mistake of characterizing
the one percept as mental picture while taking the other in
the very same sense as does the naïve realism which it
apparently refutes. It wants to prove that percepts have the
character of mental pictures by naïvely accepting the percepts
connected with one's own organism as objectively valid
facts; and over and above this, it fails to see that it confuses
two spheres of observation, between which it can find no
connection.
Critical idealism can refute naïve realism only by itself
assuming, in naïve-realistic fashion, that one's own organism
has objective existence. As soon as the idealist realizes that
the percepts connected with his own organism are exactly of
the same nature as those which naïve realism assumes to
have objective existence, he can no longer use those percepts
as a safe foundation for his theory. He would have to regard
even his own subjective organization as a mere complex of
mental pictures. But this removes the possibility of regarding
the content of the perceived world as a product of our
spiritual organization. One would have to assume that the
mental picture “color” was only a modification of the
mental picture “eye”. So-called critical idealism cannot be
proved without borrowing from naïve realism. Naive realism
can be refuted only if, in another sphere, its own assumptions
are accepted without proof as being valid.
This much, then, is certain: Investigation within the
world of percepts cannot establish critical idealism, and
consequently, cannot strip percepts of their objective
character.
Still less can the principle “the perceived world is my
mental picture” be claimed as obvious and needing no proof.
Schopenhauer
begins his chief work
(see fn 6) with the words:
The world is my mental picture — this is a truth which holds
good for everything that lives and cognizes, though man alone
can bring it into reflective and abstract consciousness. If he
really does this, he has attained to philosophical discretion. It
then becomes clear and certain to him that he knows no sun
and no earth, but only an eye that sees a sun, a hand that feels
an earth; that the world which surrounds him is there only as
mental picture, that is, only in relation to something else, to
the one who pictures it, which is he himself. If any truth can
be asserted a priori, it is this one,
for it is the expression of that
form of all possible and thinkable experience which is more
universal than all others, than time, space, or causality, for all
these presuppose it ...
This whole theory is wrecked by the fact, already mentioned,
that the eye and the hand are percepts no less than
the sun and the earth. Using Schopenhauer's expressions in
his own sense, we could reply: My eye that sees the sun, my
hand that feels the earth, are my mental pictures just as much
as the sun and the earth themselves. That with this the
whole theory cancels itself, is clear without further argument.
For only my real eye and my real hand could have the
mental pictures “sun” and “earth” as modifications of themselves;
the mental pictures “eye” and “hand” cannot have
them. Yet it is only of these mental pictures that critical
idealism is allowed to speak.
Critical idealism is totally unfitted to form an opinion
about the relationship between percept and mental picture.
It cannot begin to make the distinction,
mentioned above,
between what happens to the percept in the process of
perception and what must be inherent in it prior to perception.
We must, therefore, tackle this problem in another
way.
Footnotes:
- First Principles, Part I, 23.
- Berkeley Principles of Human Knowledge,
Part I, Section 6.
- O. Liebmann, Zur Analysis der Wirklichkeit,
p 28.
- See his Das Grundproblem der Erkenntnistheorie,
pp. 16–40.
- Das Grundproblem der Erkenntnistheorie,
pp. 37.
- Die Welt als Wille und Vorstellung.
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