The world as we know it is one of appearances. We do not know it as
it really is; we know it only as it is represented in our consciousness,
and this must be the starting point for any philosophizing. Struck by
the unreliability of the senses, Descartes doubted the existence of
everything but resolved that, since he was contemplating the world, the
act of thinking is the one thing he could be certain of and from that
the rest could be deduced. This insight was similar to that of
Schopenhauer, who insisted that only our own consciousness is known
immediately: everything else is mediated through our consciousness and
is therefore dependent on it.
But can reality be nothing more
than our representations of it? Is it possible that nothing exists as
such? Kant argued that if the world is one of appearances there must be
something that appears, 'an object independent of sensibility'. He
referred to this as the 'thing considered as it is in itself', or the
'thing-in-itself' for short. The thing-in-itself must be neither object
nor subject. And if it transcends the distinction between subject and
object it must transcend consciousness and the knowledge that attends
consciousness.
If this is so, in addition to being an object of
consciousness, everything is also a thing-in-itself. This 'existence in
itself' stands outside the subject – object relationship and has a
metaphysical existence that has its being in an unknowable world beyond
consciousness; it is a 'metaphysical being'. We can know nothing about
it because all we know are appearances, and those appearances are
structured by our given forms of understanding.
At this
stage of the argument it seems reasonable to imagine that the world
exists twice—once as an 'objective fact' independent of us and once in
our representations as a set of images projected onto some sort of
screen in our head. As the argument develops, though, it will become
apparent that there is just one world but there are two distinct ways of
apprehending it.
The main argument for the existence of the
thing-in-itself is that without it we are left with a view of the world
as nothing more than the illusion created by human consciousness.
Although we know everything we know through our consciousness—including
our senses and our cognition—this is not to say there is nothing we
cannot know. Our awareness has limits. It is this that allows for the
possibility of things existing beyond their appearances, as the
thing-in-itself.We can think about the world 'beyond' the world of
appearances, but that does not mean we know it. To use a theistic
analogy, the idea of God can never be God.
The approach of
transcendental idealism—which considers the problem of reality not from
the starting point of object or subject but through the inseparability
of the two—differs from other philosophical approaches, including the
commonsense realist one. Most philosophical approaches, at least in the
Western tradition, recognize only the subject or the object. In
particular, realists (or 'materialists') recognized only the object, and
the idealists who preceded Kant recognised only the subject. Realists
take matter as having absolute existence, independent of consciousness,
but they are then confronted with the problem of perception: if I see an
object as green but my colour-blind friend sees it as red we are
compelled to admit we cannot do without the perceiving subject. As
Schopenhauer wrote, "For 'No object without subject' is the principle
that renders all materialism for ever impossible".
Realism, which
coincides with the working assumption of everyday life, is therefore
based on nothing more than a supposition—the absolute existence of the
world beyond our senses—since we can never test the supposition by
stepping outside ourselves to see whether it is true. Such a world is
not conceivable. Thus, despite its intuitive obviousness, realism is
"the philosophy of the subject who forgets to take account of himself. "
Mysticism has been called 'a doctrine of epistemological
modesty': it recognises the limits of our knowledge. This might seem
odd at first, but on reflection we see that realism imagines there is a
world outside us which is then mirrored by a world within us that
represents the 'objective' world. In this view we imagine, if only by
implication, an all-seeing God above who observes his creation, a God
who exists independently of our consciousness. This is implicitly a
theocentric model, and Kant's revolution was to make our understanding
of the world human-centered instead of God-centred—perhaps the crucial
philosophical insight of the European Enlightenment. The world as we
see it is as we see it, rather than as it really is; it is conditioned
by our perception; it is a world of appearances. This is the meaning of
the often-quoted observation in the Talmud: "We do not see things as
they are, but as we are."
Kant did not turn man into God but took
away from man the god-like insight the realists had unwittingly
assigned to him. This is why Kant's idealism is modest and why Kant
himself was suspected of holding heretical views. Kant's intervention
followed a long and intense debate in the Catholic church over the
nature of reality, the theologians being divided between nominalists,
realists and conceptualists. As the Enlightenment dawned the consensus
converged on what was known as 'moderate realism' (especially as
formulated by Thomas Aquinas), which allowed the church's teachings to
coexist with the new science. Kant's assertion of a form of
conceptualism laid the groundwork for the emergence of humanism. In
particular, the anthropocentric model gave humans responsibility for
their moral laws and their destiny, rather than these things being
handed down by God, with the clerics acting as middlemen.
Kant
adopted the terms phenomenon and noumenon to distinguish between the
thing as it appears to us and the thing as it is in itself. Thus
'phenomenon' applies to the world of appearances, the phenomena that
inhabit our consciousness, and 'noumenon' describes the world that 'lies
behind' the world of appearances. For Kant, the difficulty lay in
establishing the need for the existence of something about which we can
know nothing. Positing the existence of the noumenon was pivotal
because if the world were nothing but appearances it would be
indistinguishable from a dream. But if there is another side to the
world we can know nothing about it, since anything we do know takes the
form of a representation, a phenomenon.
Appearances however must
be appearances of something. Then the noumenon is a thing 'so far as it
is not an object of our sensible intuition'. But there could be a
positive reason for establishing the existence of the noumenon. At one
point Kant entertained the idea that there might be a special kind of
awareness, beyond our ordinary consciousness, that allows us special
knowledge of the noumenon. He suggested "a peculiar mode of intuition . .
. the very possibility of which we have no notion" that would allow us
to understand the noumenon
positively, as "an object of a
non-sensible intuition". But he then rejected such a notion and
reverted to negative arguments for the noumenon.
Although
declaring that "we are not entitled to maintain that sensibility is the
only possible mode of intuition", Kant became known, adopted a position
of philosophical humility, shying away from this postulated form of
non-sensible intuition because such a notion "lies absolutely beyond
what we could know". He conceded the possibility of a form of intuition
beyond everyday senses and cognition but argued that since our faculties
can know nothing of this it is legitimate to motivate the existence of
the noumenon only in the negative sense. Kant's 'distinctive concern
was to vindicate the authority of reason' after centuries of
superstition and ecclesiastical dogma. He was determined to stay true to
the Enlightenment value of stringent rationality and resisted the
temptation to resort to notions that seemed dangerously close to
theology. So, despite professing to be a Christian throughout his life,
he used the existence of the noumenon to structure the void left by the
boundedness of the world of appearances—as if to prevent theists from
filling it with God. Thus, in the end he insisted that the division
between phenomenon and noumenon can be supported only in the negative
sense. The willingness to argue for the existence of a form of
'nonsensible intuition' was the decisive break from Kant that
Schopenhauer made.
If we cannot know the world as it is in itself
but can know it only through our perceptions, how is it that our
perceptions are so uniform we can communicate with each other
effectively through a shared view of the world? Kant maintained that
humans' capacity to perceive the outside world and thus form
representations of it depends on certain 'conditions of sensibility'
that exist before the experiences themselves, notably the forms of
space, time and causality. These are inbuilt forms of the human mind,
and they provide the structure that allows us to receive in an
intelligible way the sensory data of the outside world. They are a
priori—that is, present before experience. As a result, instead of
learning the forms of space, time and causality through experience of
the world,we in fact impose them on the world.
This is a
mind-bending idea. Putting causality aside for the moment, in this view
space and time are the two pure forms of sensory intuition. Space is the
property of the mind by which we represent objects outside ourselves,
whereas we represent everything that relates to our inward mental or
sensory consideration in terms of time. Space and time thus provide the
pure forms by which we apprehend the world; they do not belong to things
in themselves. In the case of space, we do not learn by experience to
understand and use the concept because it already structures our
capacity to perceive the world. It is 'the foundation of all external
intuitions' or appearances. Indeed, the priori form of space makes all
external appearances possible. Geometry is the science of space that
developed wholly independently of any real object and does no more than
apply intelligence to the form of space. If we imagine an object from
which we progressively strip away all features—colour, hardness, weight,
and so on—we would still be left with the space it occupies, 'and this
it is utterly impossible to annihilate in thought'.
So, rather
than being properties inherent in the 'object' (the material world
outside us), these priori forms are brought by the subject to the world
and used to structure representations of it. Indeed, these forms are
essential to allow communication between subject and object—that is, the
opportunity for the subject to structure the world in a useful way.
This is a radical and counter-intuitive position since Kant is arguing
that, instead of assuming that 'our knowledge must conform to the
objects' as they are actually given outside of us, 'the objects must
conform to our knowledge'. Although this might seem a monstrous idea,
because humans are seen to 'create' the world, the opposite is the case.
Instead of humans being able to capture reality as it is, we are
captives of our representations of the world and cannot know it as it
really is.
According to Kant, humans provide the rules by which
we understand the world. Kant called these rules we bring to the world
the 'legislation for nature'. They allow us to order our perceptions.
And they make possible pure understanding—cognition that depends on
concepts alone, such as pure mathematics. The rules we bring to the
outside world are common to all of us and therefore give our
understanding objectivity. Realists, on the other hand, do not
recognize these rules as priori conditions; instead, they attribute them
to the outside world as inherent qualities of it that each human must
learn anew through experience.
The properties of the world as we
perceive it do not belong inherently to the world but are 'imposed' on
the world by our perception of it. This does not mean the only reality
is the world of appearances; rather, it means that, to the extent that
we perceive and think, we do so only in terms of appearances. There is a
reality 'behind' appearances, or at least it is necessary to posit such
a world because appearances presuppose things that appear.
Now
you may notice that many of these concepts have a similarity with
Eastern Mysticism. Schopenhauer was the first Western philosopher to
appreciate the deep insights of the East, where it has been understood
for millennia that the world as we experience it has no real being but
is instead 'a ceaseless becoming'. In the Hindu Vedas—the oldest books
in the world—the idea can be found in the doctrine of
Maya, the
chimera of the everyday world, 'an unstable and inconstant illusion
without substance . . . a veil enveloping human consciousness'. These
ideas, Schopenhauer noted, were produced not from philosophising by the
sages but from 'the direct utterance of their consciousness'.
As
with time, so with space: both are forms that inhere not in the world
itself but rather in our representations of it. Thus in the
Upanishads
(a later distillation of the Vedas), space is, in addition to being a
property of things, the 'creator' of things, and all things are
contained within space as Brahman: "Space, as it is called, is the
bringer into being of name and form. That which contains them is
brahman, the immortal." All phenomenal forms exist 'inside' the
boundless and timeless ground. When the subject brings the form of space
to the world, differentiation is created since the spatial coordinates
of a thing distinguish it from another thing. In the Kantian view, the
phenomenon is characterised by multiplicity but the noumenon is
undifferentiated; in Schopenhauer's words, "only the one and identical
essence can manifest itself in all those phenomena." This idea
reappeared across the ancient and modern worlds, in the writings of the
Platonists and the Sufis and the works of Spinoza and various Christian
mystics, before Kant took it up and argued it using the rules of logic
rather than direct realisation.
In the Upanishads the idea of oneness from which all else is manifest is explicit in the idea of
Brahman.
The unifying or subtle essence can be interpreted as the sacred power
of the whole universe—that is, the universal 'energy' that is the
essence of the noumenon. It is the source of creation yet is uncreated.
Thus Brahman is said to be 'self-born'. In Buddhist teaching, which is
atheistic, this is captured in the notion of the 'suchness' of the
world, the essential quality that infuses all things and reflects the
oneness of the whole creation: "When the Ten Thousand things are viewed
in their oneness, we return to the Origin and remain where we have
always been."
Aldous Huxley summarised the insight of the sages of all traditions by describing a hierarchy of the real:
"The
manifold world of our everyday experience is real with a relative
reality that is, on its own level, unquestionable; but this relative
reality has its being within and because of the absolute Reality, which,
on account of the incommensurable otherness of its eternal nature, we
can never hope to describe, even though it is possible for us directly
to apprehend it."
