Immanuel Kant, the most celebrated of German metaphysicians, was
born at Koenigsberg on April 22, 1724, and died on February 12,
1804. Taking his degree at Koenigsberg, he speedily entered on a
professional career, which he quietly and strenuously pursued for
over thirty years. Though his lectures were limited to the topics
with which he was concerned as professor of logic and philosophy,
his versatility is evidenced by the fact that he was offered the
chair of poetry, which he declined. His lasting reputation began
with the publication, in 1781, of his wonderful "Critique of Pure
Reason" ("Kritik der reinen Vernunft"). Within twelve years of its
appearance it was expounded in all the leading universities, and
even penetrated into the schools of the Church of Rome. Kant was
the first European thinker who definitely grasped the conception of
a critical philosophy, though he was doubtless aided by the
tendency of Locke's psychology. He did much to counteract the
sceptical influence of Hume. The main object of his "Critique of
Pure Reason" is to separate the necessary and universal in the
realm of knowledge from the merely experimental or empirical. This
little version of Kant's celebrated work has been prepared from the
German text.
_I.--Knowledge Transcendental: AEsthetic_
Experience is something of which we are conscious. It is the first
result of our comprehension, but it is not the limit of our
understanding, since it stimulates our faculty of reason, but does not
satisfy its desire for knowledge. While all our knowledge may begin with
sensible impressions or experience, there is an element in it which does
not rise from this source, but transcends it. That knowledge is
transcendental which is occupied not so much with mere outward objects
as with our manner of knowing those objects, that is to say, with our _a
priori_ concepts of them. All our knowledge is either _a priori_ or _a
posteriori_. That is _a posteriori_ knowledge which is derived from
sensible experience as including sensible impressions or states; while
_a priori_ knowledge is that which is not thus gained, but consists of
whatever is universal or necessary. A complete "Transcendental
Philosophy" would be a systematic exposition of all that is _a priori_
in human knowledge, or of "all the principles of pure reason." But a
"Critique of Pure Reason" cannot include all this. It can do little more
than deal with the synthetic element or quality in _a priori_ knowledge,
as distinguished from the analytic element.
We perceive objects through our sensibility which furnishes us, as our
faculty of receptivity, with those intuitions that become translated
into thought by means of the understanding. This is the origin of our
conceptions, or ideas. I denominate as _matter_ that which in a
phenomenon corresponds to sensation; while I call _form_ that quality of
matter which presents it in a perceived order. Only matter is presented
to our minds _a posteriori_; as to form, this must inevitably exist in
the mind _a priori_, and therefore it can be considered apart from all
sensation.
Pure representation, entirely apart from sensation, in a transcendental
signification, forms the pure intuition of the mind, existing in it as a
mere form of sensibility. Transcendental aesthetic is the science of all
the principles of sensibility. But transcendental logic is the science
of the principles of pure thought. In studying the former we shall find
that there are two pure forms of sensuous intuition, namely, space and
time.
Are space and time actual entities? Or are they only relations of
things? Space is simply the form of all the phenomena of external
senses; that is, it is the subjective condition of the sensibility under
which alone external intuition is possible. Thus, the form of all
phenomena may exist _a priori_ in the soul as a pure intuition previous
to all experience. So we can only speak of space and of extended
objects from the standpoint of human reason. But when we have abstracted
all the forms perceived by our sensibility, there remains a pure
intuition which we call space. Therefore our discussion teaches us the
objective validity of space with regard to all that can appear before us
externally as an object; but equally the subjective ideality of space,
with regard to things if they are considered in themselves by our
reason, that is, without taking into account the nature of our
sensibility.
Time is not empirically conceived of; that is, it is not experimentally
apprehended. Time is a necessary representation on which all intuitions
are dependent, and the representation of time to the mind is thus given
_a priori._ In it alone can phenomena be apprehended. These may vanish,
but time cannot be put aside.
Time is not something existing by itself independently, but is the
formal condition _a priori_ of all phenomena. If we deduct our own
peculiar sensibility, then the idea of time disappears indeed, because
it is not inherent in any object, but only in the subject which
perceives that object. Space and time are essential _a priori_ ideas,
and they are the necessary conditions of all particular perceptions.
From the latter and their objects we can, in imagination, without
exception, abstract; from the former we cannot.
Space and time are therefore to be regarded as the necessary _a priori_
pre-conditions of the possibility and reality of all phenomena. It is
clear that transcendental aesthetic can obtain only these two elements,
space and time, because all other concepts belong to the senses and
pre-suppose experience, and so imply something empirical. For example,
the concept of motion pre-supposes something moving, but in space
regarded alone there is nothing that moves; therefore, whatever moves
must be recognised by experience, and is a purely empirical datum.
_II.--Transcendental Logic_
Our knowledge is derived from two fundamental sources of the
consciousness. The first is the faculty of receptivity of impressions;
the second, the faculty of cognition of an object by means of these
impressions or representations, this second power being sometimes styled
spontaneity of concepts. By the first, an object is given to us; by the
second it is thought of in the mind. Thus intuition and concepts
constitute the elements of our entire knowledge, for neither intuition
without concepts, nor concepts without intuition, can yield any
knowledge whatever. Hence arise two branches of science, aesthetic and
logic, the former being the science of the rules of sensibility; the
latter, the science of the rules of the understanding.
Logic can be treated in two directions: either as logic of the general
use of the understanding, or of some particular use of it. The former
includes the rules of thought, without which there can be no use of the
understanding; but it has no regard to the objects to which the
understanding is applied. This is elementary logic. But logic of the
understanding in some particular use includes rules of correct thought
in relation to special classes of objects; and this latter logic is
generally taught in schools as preliminary to the study of sciences.
Thus, general logic takes no account of any of the contents of
knowledge, but is limited simply to the consideration of the forms of
thought. But we are constrained by anticipation to form an idea of a
logical science which has to deal not only with pure thought, but also
has to determine the origin, validity, and extent of the knowledge to
which intuitions relate, and this science might be styled transcendental
logic.
In transcendental aesthetic we isolated the faculty of sensibility. So in
transcendental logic we isolate the understanding, concentrating our
consideration on that element of thought which has its source simply in
the understanding. But transcendental logic must be divided into
transcendental analytic and transcendental dialectic. The former is a
logic of truth, and is intended to furnish a canon of criticism. When
logic is used to judge not analytically, but to judge synthetically of
objects in general, it is called transcendental dialectic, which serves
as a protection against sophistical fallacy.