7. The Kantian School. These rules and schemata,
the forms of knowledge, were believed by Immanuel
Kant to be unanalyzable into perceptual data. We may
perceive colors and sounds but we cannot perceive the
spatial matrix in which they are located. For if we
empty space of all perceptual content, nothing is left.
Similar arguments apply to time. Hence both space
and time in Kant became the forms of perception, ideas
by which the mind organizes its perceptions but which
have no perceptual correspondence whatsoever. Simi-
larly when we make scientific judgments of causality,
quantity, quality, or necessity, there are no sensory data
which could possibly compose them. These categories
are the means by which we think, and they have no
sources beyond our minds. It had been pointed out in
the seventeenth century by Géraud de Cordemoy and
Nicolas Malebranche that one could see, for instance,
a rolling ball touch another, but one could not see it
cause the other to move.
Causation, then, is an idea of ours which we project
into the world of observation. Similarly Hume had
pointed out that we could observe the regularity of
events but not their necessity. Necessity was one of
our feelings induced by the sight of regularity. Kant's
categories of the understanding were in an analogous
situation. They were the mind's way of making experi-
ence intelligible. They were regulatory principles
which gave structure to our knowledge, knowledge
whose content might be perceptual but whose form
was entirely subjective.
Hume had shown to the satisfaction of most philoso-
phers the impossibility of penetrating the perceptual
screen of impressions and reaching some material cause
which might explain its presence. In Kant the question
of such a cause does not arise, for perceptual ideas
exist as if they were the experiences of a single over-
individual mind. They take the place of an objective
world. But besides these ideas there are the two types
of forms (space, time) and categories through which
all men are bound to order their knowledge. Hence,
as was evident to Kant's immediate successor, Fichte,
any talk about unknowable things-in-themselves is
nonsense. For as soon as we begin to talk, we inescap-
ably use the categories. And the categories are relevant
only to our ideas.
There is moreover another set of ideas in Kant and
these have no ground whatsoever in perception or
science. He recognized that we have religious and
moral ideas, ideas of God, freedom, and immortality.
These ideas cannot be correlated with any perceptions
for the simple reason that we admittedly do not see
(i.e., perceive) what they stand for. Moreover they are
not categories of the understanding, for science not
only can get along very well without them, but actually
contradicts one of them, the idea of freedom, and gives
no evidence for the truth of the other two.
One might conclude that they were false and should
be abandoned. But Kant introduced a new function
for an idea at this point. These three ideas, though
antiscientific, were necessary postulates for ethics.
Doing one's duty would be unjustifiable if there were
no God, if the will were not free, and if life ended
in the grave. Kant did not entertain the possibility that
life is a tragedy and duty an illusion. On the contrary,
he assumed that the world must be so made that doing
one's duty was imperative. Thus a new criterion for
the truth of an idea was introduced, its necessity for
the justification of moral values.
From then on it was possible to think of the world
as essentially a stage for human life and for the solution
of human problems, which was a reversion oddly
enough to the medieval point of view. Philosophy, to
be sure, was no longer the handmaiden of theology
but of ethics. The innovation as it was made by Kant
and developed by Fichte may not have been radical,
but it became so as the nineteenth and twentieth cen-
turies evolved. For if an idea could be a postulate for
the religious and moral life, why could it not be a
postulate for the aesthetic, the political, the economic
life? An idea could easily become an instrument by
means of which a man could substantiate any of his
ends, ends which could be chosen rationally by reasons
which were more useful than true. In such a case the
true would turn into the useful.
Schopenhauer had maintained that reasoning was at
the service of the will-to-live, as Nietzsche was to put
it at the service of the will-to-power. Ideas were a mask
for desires, a doctrine which was developed by Sig-
mund Freud, substituting the libido for the will. The
great Kantian scholar, Hans Vaihinger (1852-1933)
made all ideas fictions of various types which we set
up to make the world intelligible. These and similar
views seemed to dethrone the ideas and to become
not the guideposts to impersonal truth, completely
detached from human desires, forming the matrix of
reality, but rather signs of what we would like to
believe, conventions by means of which we can confer
plausibility upon our thoughts and aspirations. Seldom
has the history of an idea manifested such a reversal
of meaning.
