Kant's mistaken formulation of the problem has had a greater or lesser
influence on all subsequent students of the Theory of Knowledge. For
Kant, the view that all objects which are given to us in experience
are ideas in our minds is a consequence of his theory of the a
priori. For nearly all his successors, it has become the first
principle and starting-point of their epistemological systems. It is
said that the first and most immediate truth is, simply and solely,
the proposition that we know our own ideas. This has come to be
a well-nigh universal conviction among philosophers. G. E. Schulze
maintains in his Ænesidemus, as early as 1792, that all our cognitions
are mere ideas and that we can never transcend our ideas. Schopenhauer
puts forward, with all the philosophical pathos which distinguishes
him, the view that the permanent achievement of Kant's philosophy
is the thesis that "the world is my idea." To Eduard von Hartmann
this thesis is so incontestable, that he addresses his treatise,
Kritische Grundlegung des Transcendentalen Realismus, exclusively
to readers who have achieved critical emancipation from the naïve
identification of the world of perception with the thing-in-itself. He
demands of them that they shall have made clear to themselves the
absolute heterogeneity of the object of perception which through the
act of representation has been given as a subjective and ideal content
of consciousness, and of the thing-in-itself which is independent of
the act of representation and of the form of consciousness and which
exists in its own right. His readers are required to be thoroughly
convinced that the whole of what is immediately given to us consists
of ideas. [37] In his latest work on Theory of Knowledge, Hartmann
does, indeed, attempt to give reasons for this view. What value should
be attached to these reasons by an unprejudiced Theory of Knowledge
will appear in the further course of our discussions. Otto Liebmann
posits as the sacrosanct first principle of the Theory of Knowledge
the proposition, "Consciousness cannot transcend itself." [38] Volkelt
has called the proposition that the first and most immediate truth is
the limitation of all our knowledge, in the first instance, to our own
ideas exclusively, the positivistic principle of knowledge. He regards
only those theories of knowledge as "in the fullest sense critical"
which "place this principle, as the only fixed starting-point of
philosophy, at the head of their discussions and then consistently
think out its consequences." [39] Other philosophers place other
propositions at the head of the Theory of Knowledge, e.g., the
proposition that its real problem concerns the relation between
Thought and Being, and the possibility of a mediation between them;
[40] or that it concerns the way in which Being becomes an object
of Consciousness; [41] and many others. Kirchmann starts from two
epistemological axioms, "Whatever is perceived is," and, "Whatever
is self-contradictory, is not." [42] According to E. L. Fischer,
knowledge is the science of something actual, something real, [43]
and he criticises this dogma as little as does Goering who asserts
similarly, "To know means always to know something which is. This is a
fact which cannot be denied either by scepticism or by Kant's critical
philosophy." [44] These two latter thinkers simply lay down the law:
This is what knowledge is. They do not trouble to ask themselves with
what right they do it.
But, even if these various propositions were correct, or led to correct
formulations of the problem, it would still be impossible to discuss
them at the outset of the Theory of Knowledge. For, they all belong, as
positive and definite cognitions, within the realm of knowledge. To say
that my knowledge extends, in the first instance, only to my ideas,
is to express in a perfectly definite judgment something which I
know. In this judgment I qualify the world which is given to me by
the predicate "existing in the form of idea." But how am I to know,
prior to all knowledge, that the objects given to me are ideas?
The best way to convince ourselves of the truth of the assertion
that this proposition has no right to be put at the head of the
Theory of Knowledge, is to retrace the way which the human mind must
follow in order to reach this proposition, which has become almost
an integral part of the whole modern scientific consciousness. The
considerations which have led to it are systematically summarised,
with approximate exhaustiveness, in Part I of Eduard von Hartmann's
treatise, Das Grundproblem der Erkenntnistheorie. His statement, there,
may serve as a sort of guiding-thread for us in our task of reviewing
the reasons which may lead to the acceptance of this proposition.
These reasons are physical, psycho-physical, physiological, and
properly philosophical.
The Physicist is led by observation of the phenomena which occur
in our environment when, e.g., we experience a sensation of sound,
to the view that there is nothing in these phenomena which in the
very least resembles what we perceive immediately as sound. Outside,
in the space which surrounds us, nothing is to be found except
longitudinal oscillations of bodies and of the air. Thence it is
inferred that what in ordinary life we call "sound" or "tone" is
nothing but the subjective reaction of our organism to these wave-like
oscillations. Similarly, it is inferred that light and colour and
heat are purely subjective. The phenomena of colour-dispersion, of
refraction, of interference, of polarisation, teach us that to the
just-mentioned sensations there correspond in the outer space certain
transverse oscillations which we feel compelled to ascribe, in part
to the bodies, in part to an immeasurably fine, elastic fluid, the
"ether." Further, the Physicist is driven by certain phenomena in the
world of bodies to abandon the belief in the continuity of objects in
space, and to analyse them into systems of exceedingly minute particles
(molecules, atoms), the size of which, relatively to the distances
between them, is immeasurably small. Thence it is inferred that all
action of bodies on each other is across the empty intervening space,
and is thus a genuine actio in distans. The Physicist believes himself
justified in holding that the action of bodies on our senses of touch
and temperature does not take place through direct contact, because
there must always remain a definite, if small, distance between the
body and the spot on the skin which it is said to "touch." Thence it
is said to follow that what we sense as hardness or heat in bodies
is nothing but the reactions of the end-organs of our touch- and
temperature-nerves to the molecular forces of bodies which act upon
them across empty space.
These considerations from the sphere of Physics are supplemented
by the Psycho-physicists with their doctrine of specific
sense-energies. J. Müller has shown that every sense can be affected
only in its own characteristic way as determined by its organisation,
and that its reaction is always of the same kind whatever may be the
external stimulus. If the optical nerve is stimulated, light-sensations
are experienced by us regardless of whether the stimulus was pressure,
or an electric current, or light. On the other hand, the same external
phenomena produce quite different sensations according as they are
perceived by different senses. From these facts the inference has
been drawn that there occurs only one sort of phenomenon in the
external world, viz., motions, and that the variety of qualities of
the world we perceive is essentially a reaction of our senses to these
motions. According to this view, we do not perceive the external world
as such, but only the subjective sensations which it evokes in us.
Physiology adds its quota to the physical arguments. Physics deals
with the phenomena which occur outside our organisms and which
correspond to our percepts. Physiology seeks to investigate the
processes which go on in man's own body when a certain sensation is
evoked in him. It teaches us that the epidermis is wholly insensitive
to the stimuli in the external world. Thus, e.g., if external stimuli
are to affect the end-organs of our touch-nerves on the surface of
our bodies, the oscillations which occur outside our bodies have to
be transmitted through the epidermis. In the case of the senses of
hearing and of sight, the external motions have, in addition, to be
modified by a number of structures in the sense-organs, before they
reach the nerves. The nerves have to conduct the effects produced in
the end-organs up to the central organ, and only then can take place
the process by means of which purely mechanical changes in the brain
produce sensations. It is clear that the stimulus which acts upon
the sense-organs is so completely changed by the transformations
which it undergoes, that every trace of resemblance between the
initial impression on the sense-organs and the final sensation in
consciousness must be obliterated. Hartmann sums up the outcome of
these considerations in these words: "This content of consciousness
consists, originally, of sensations which are the reflex responses
of the soul to the molecular motions in the highest cortical centres,
but which have not the faintest resemblance to the molecular motions
by which they are elicited."
If we think this line of argument through to the end, we must agree
that, assuming it to be correct, there survives in the content
of our consciousness not the least element of what may be called
"external existence."
To the physical and physiological objections against so-called "Naïve
Realism" Hartmann adds some further objections which he describes
as philosophical in the strict sense. A logical examination of the
physical and physiological objections reveals that, after all,
the desired conclusion can be reached only if we start from the
existence and nexus of external objects, just as these are assumed by
the ordinary naïve consciousness, and then inquire how this external
world can enter the consciousness of beings with organisms such as
ours. We have seen that every trace of such an external world is lost
on the way from the impression on the sense-organ to the appearance
of the sensation in our consciousness, and that in the latter nothing
survives except our ideas. Hence, we have to assume that the picture
of the external world which we actually have, has been built up by
the soul on the basis of the sensations given to it. First, the soul
constructs out of the data of the senses of touch and sight a picture
of the world in space, and then the sensations of the other senses
are fitted into this space-system. When we are compelled to think of
a certain complex of sensations as belonging together, we are led
to the concept of substance and regard substance as the bearer of
sense-qualities. When we observe that some sense-qualities disappear
from a substance and that others appear in their place, we ascribe
this event in the world of phenomena to a change regulated by the law
of causality. Thus, according to this view, our whole world-picture
is composed of subjective sensations which are ordered by the activity
of our own souls. Hartmann says, "What the subject perceives is always
only modifications of its own psychic states and nothing else." [45]
Now let us ask ourselves, How do we come by such a view? The
bare skeleton of the line of thought which leads to it is as
follows. Supposing an external world exists, we do not perceive
it as such but transform it through our organisation into a world
of ideas. This is a supposition which, when consistently thought
out, destroys itself. But is this reflection capable of supporting
any positive alternative? Are we justified in regarding the world,
which is given to us, as the subjective content of ideas because the
assumptions of the naïve consciousness, logically followed out, lead to
this conclusion? Our purpose is, rather, to exhibit these assumptions
themselves as untenable. Yet, so far we should have found only that
it is possible for a premise to be false and yet for the conclusion
drawn from it to be true. Granted that this may happen, yet we can
never regard the conclusion as proved by means of that premise.
It is usual to apply the title of "Naïve Realism" to the theory
which accepts as self-evident and indubitable the reality of the
world-picture which is immediately given to us. The opposite theory,
which regards this world as merely the content of our consciousness, is
called "Transcendental Idealism." Hence, we may sum up the outcome of
the above discussion by saying, "Transcendental Idealism demonstrates
its own truth, by employing the premises of the Naïve Realism which it
seeks to refute." Transcendental Idealism is true, if Naïve Realism is
false. But the falsity of the latter is shown only by assuming it to be
true. Once we clearly realise this situation, we have no choice but to
abandon this line of argument and to try another. But are we to trust
to good luck, and experiment about until we hit by accident upon the
right line? This is Eduard von Hartmann's view when he believes himself
to have shown the validity of his own epistemological standpoint, on
the ground that his theory explains the phenomena whereas its rivals
do not. According to his view, the several philosophical systems are
engaged in a sort of struggle for existence in which the fittest is
ultimately accepted as victor. But this method appears to us to be
unsuitable, if only for the reason that there may well be several
hypotheses which explain the phenomena equally satisfactorily. Hence,
we had better keep to the above line of thought for the refutation
of Naïve Realism, and see where precisely its deficiency lies. For,
after all, Naïve Realism is the view from which we all start out. For
this reason alone it is advisable to begin by setting it right. When
we have once understood why it must be defective, we shall be led
upon the right path with far greater certainty than if we proceed
simply at haphazard.
The subjectivism which we have sketched above is the result of the
elaboration of certain facts by thought. Thus, it takes for granted
that, from given facts as starting-point, we can by consistent
thinking, i.e., by logical combination of certain observations, gain
correct conclusions. But our right thus to employ our thinking remains
unexamined. There, precisely, lies the weakness of this method. Whereas
Naïve Realism starts from the unexamined assumption that the contents
of our perceptual experience have objective reality, the Idealism
just described starts from the no less unexamined conviction that by
the use of thought we can reach conclusions which are scientifically
valid. In contrast to Naïve Realism, we may call this point of view
"Naïve Rationalism." In order to justify this term, it may be well to
insert here a brief comment on the concept of the "Naïve." A. Döring,
in his essay Über den Begriff des Naiven Realismus, [46] attempts a
more precise determination of this concept. He says, "The concept
of the Naïve marks as it were the zero-point on the scale of our
reflection upon our own activity. In content the Naïve may well
coincide with the True, for, although the Naïve is unreflecting and,
therefore, uncritical or a-critical, yet this lack of reflection and
criticism excludes only the objective assurance of truth. It implies
the possibility and the danger of error, but it does not imply the
necessity of error. There are naïve modes of feeling and willing as
there are naïve modes of apprehending and thinking, in the widest sense
of the latter term. Further, there are naïve modes of expressing these
inward states in contrast with their repression or modification through
consideration for others and through reflection. Naïve activity is
not influenced, at least not consciously, by tradition, education, or
imposed rule. It is in all spheres (as its root nativus, brings out),
unconscious, impulsive, instinctive, dæmonic activity." Starting from
this account, we will try to determine the concept of the Naïve still
more precisely. In every activity we may consider two aspects--the
activity itself and our consciousness of its conformity to a law. We
may be wholly absorbed in the former, without caring at all for
the latter. The artist is in this position, who does not know in
reflective form the laws of his creative activity but yet practises
these laws by feeling and sense. We call him "naïve." But there is
a kind of self-observation which inquires into the laws of one's
own activity and which replaces the naïve attitude, just described,
by the consciousness of knowing exactly the scope and justification
of all one does. This we will call "critical." This account seems to
us best to hit off the meaning of this concept which, more or less
clearly understood, has since Kant acquired citizen-rights in the
world of philosophy. Critical reflection is, thus, the opposite of
naïve consciousness. We call an attitude "critical" which makes itself
master of the laws of its own activity in order to know how far it
can rely on them and what are their limits. Theory of Knowledge can
be nothing if not a critical science. Its object is precisely the most
subjective activity of man--knowing. What it aims at exhibiting is the
laws to which knowing conforms. Hence, the naïve attitude is wholly
excluded from this science. Its claim to strength lies precisely
in that it achieves what many minds, interested in practice rather
than in theory, pride themselves on never having attempted, viz.,
"thinking about thought."