SS 18. In Cognition, its Application to Objects of Experience is
the only legitimate use of the Category.
To think an object and to cognize an object are by no means the same
thing. In cognition there are two elements: firstly, the conception,
whereby an object is cogitated (the category); and, secondly, the
intuition, whereby the object is given. For supposing that to the
conception a corresponding intuition could not be given, it would
still be a thought as regards its form, but without any object, and no
cognition of anything would be possible by means of it, inasmuch as, so
far as I knew, there existed and could exist nothing to which my
thought could be applied. Now all intuition possible to us is sensuous;
consequently, our thought of an object by means of a pure conception of
the understanding, can become cognition for us only in so far as this
conception is applied to objects of the senses. Sensuous intuition is
either pure intuition (space and time) or empirical intuition--of that
which is immediately represented in space and time by means of sensation
as real. Through the determination of pure intuition we obtain a priori
cognitions of objects, as in mathematics, but only as regards their form
as phenomena; whether there can exist things which must be intuited
in this form is not thereby established. All mathematical conceptions,
therefore, are not per se cognition, except in so far as we presuppose
that there exist things which can only be represented conformably to the
form of our pure sensuous intuition. But things in space and time
are given only in so far as they are perceptions (representations
accompanied with sensation), therefore only by empirical representation.
Consequently the pure conceptions of the understanding, even when
they are applied to intuitions a priori (as in mathematics), produce
cognition only in so far as these (and therefore the conceptions of the
understanding by means of them) can be applied to empirical intuitions.
Consequently the categories do not, even by means of pure intuition
afford us any cognition of things; they can only do so in so far as they
can be applied to empirical intuition. That is to say, the categories
serve only to render empirical cognition possible. But this is what
we call experience. Consequently, in cognition, their application to
objects of experience is the only legitimate use of the categories.
SS 19.
The foregoing proposition is of the utmost importance, for it determines
the limits of the exercise of the pure conceptions of the understanding
in regard to objects, just as transcendental aesthetic determined the
limits of the exercise of the pure form of our sensuous intuition.
Space and time, as conditions of the possibility of the presentation
of objects to us, are valid no further than for objects of sense,
consequently, only for experience. Beyond these limits they represent
to us nothing, for they belong only to sense, and have no reality apart
from it. The pure conceptions of the understanding are free from this
limitation, and extend to objects of intuition in general, be the
intuition like or unlike to ours, provided only it be sensuous, and not
intellectual. But this extension of conceptions beyond the range of our
intuition is of no advantage; for they are then mere empty conceptions
of objects, as to the possibility or impossibility of the existence of
which they furnish us with no means of discovery. They are mere forms
of thought, without objective reality, because we have no intuition to
which the synthetical unity of apperception, which alone the categories
contain, could be applied, for the purpose of determining an object. Our
sensuous and empirical intuition can alone give them significance and
meaning.
If, then, we suppose an object of a non-sensuous intuition to be given
we can in that case represent it by all those predicates which are
implied in the presupposition that nothing appertaining to sensuous
intuition belongs to it; for example, that it is not extended, or in
space; that its duration is not time; that in it no change (the effect
of the determinations in time) is to be met with, and so on. But it
is no proper knowledge if I merely indicate what the intuition of the
object is not, without being able to say what is contained in it, for I
have not shown the possibility of an object to which my pure conception
of understanding could be applicable, because I have not been able to
furnish any intuition corresponding to it, but am only able to say that
our intuition is not valid for it. But the most important point is
this, that to a something of this kind not one category can be found
applicable. Take, for example, the conception of substance, that is,
something that can exist as subject, but never as mere predicate; in
regard to this conception I am quite ignorant whether there can really
be anything to correspond to such a determination of thought, if
empirical intuition did not afford me the occasion for its application.
But of this more in the sequel.
SS 20. Of the Application of the Categories to Objects of the
Senses in general.
The pure conceptions of the understanding apply to objects of intuition
in general, through the understanding alone, whether the intuition be
our own or some other, provided only it be sensuous, but are, for
this very reason, mere forms of thought, by means of which alone no
determined object can be cognized. The synthesis or conjunction of the
manifold in these conceptions relates, we have said, only to the unity
of apperception, and is for this reason the ground of the possibility
of a priori cognition, in so far as this cognition is dependent on the
understanding. This synthesis is, therefore, not merely transcendental,
but also purely intellectual. But because a certain form of sensuous
intuition exists in the mind a priori which rests on the receptivity
of the representative faculty (sensibility), the understanding, as a
spontaneity, is able to determine the internal sense by means of the
diversity of given representations, conformably to the synthetical
unity of apperception, and thus to cogitate the synthetical unity of
the apperception of the manifold of sensuous intuition a priori, as the
condition to which must necessarily be submitted all objects of human
intuition. And in this manner the categories as mere forms of thought
receive objective reality, that is, application to objects which are
given to us in intuition, but that only as phenomena, for it is only of
phenomena that we are capable of a priori intuition.
This synthesis of the manifold of sensuous intuition, which is possible
and necessary a priori, may be called figurative (synthesis speciosa),
in contradistinction to that which is cogitated in the mere category
in regard to the manifold of an intuition in general, and is
called connection or conjunction of the understanding (synthesis
intellectualis). Both are transcendental, not merely because they
themselves precede a priori all experience, but also because they form
the basis for the possibility of other cognition a priori.
But the figurative synthesis, when it has relation only to the
originally synthetical unity of apperception, that is to the
transcendental unity cogitated in the categories, must, to be
distinguished from the purely intellectual conjunction, be entitled the
transcendental synthesis of imagination. Imagination is the faculty of
representing an object even without its presence in intuition. Now, as
all our intuition is sensuous, imagination, by reason of the subjective
condition under which alone it can give a corresponding intuition to the
conceptions of the understanding, belongs to sensibility. But in so far
as the synthesis of the imagination is an act of spontaneity, which is
determinative, and not, like sense, merely determinable, and which is
consequently able to determine sense a priori, according to its form,
conformably to the unity of apperception, in so far is the imagination
a faculty of determining sensibility a priori, and its synthesis of
intuitions according to the categories must be the transcendental
synthesis of the imagination. It is an operation of the understanding on
sensibility, and the first application of the understanding to objects
of possible intuition, and at the same time the basis for the
exercise of the other functions of that faculty. As figurative, it is
distinguished from the merely intellectual synthesis, which is produced
by the understanding alone, without the aid of imagination. Now, in
so far as imagination is spontaneity, I sometimes call it also the
productive imagination, and distinguish it from the reproductive, the
synthesis of which is subject entirely to empirical laws, those of
a**ociation, namely, and which, therefore, contributes nothing to the
explanation of the possibility of a priori cognition, and for this
reason belongs not to transcendental philosophy, but to psychology.
We have now arrived at the proper place for explaining the paradox which
must have struck every one in our exposition of the internal sense (SS
6), namely--how this sense represents us to our own consciousness, only
as we appear to ourselves, not as we are in ourselves, because, to wit,
we intuite ourselves only as we are inwardly affected. Now this appears
to be contradictory, inasmuch as we thus stand in a pa**ive relation
to ourselves; and therefore in the systems of psychology, the internal
sense is commonly held to be one with the faculty of apperception, while
we, on the contrary, carefully distinguish them.
That which determines the internal sense is the understanding, and its
original power of conjoining the manifold of intuition, that is, of
bringing this under an apperception (upon which rests the possibility
of the understanding itself). Now, as the human understanding is not in
itself a faculty of intuition, and is unable to exercise such a power,
in order to conjoin, as it were, the manifold of its own intuition, the
synthesis of understanding is, considered per se, nothing but the unity
of action, of which, as such, it is self-conscious, even apart from
sensibility, by which, moreover, it is able to determine our internal
sense in respect of the manifold which may be presented to it
according to the form of sensuous intuition. Thus, under the name of a
transcendental synthesis of imagination, the understanding exercises an
activity upon the pa**ive subject, whose faculty it is; and so we
are right in saying that the internal sense is affected thereby.
Apperception and its synthetical unity are by no means one and the
same with the internal sense. The former, as the source of all our
synthetical conjunction, applies, under the name of the categories, to
the manifold of intuition in general, prior to all sensuous intuition of
objects. The internal sense, on the contrary, contains merely the form
of intuition, but without any synthetical conjunction of the manifold
therein, and consequently does not contain any determined intuition,
which is possible only through consciousness of the determination of
the manifold by the transcendental act of the imagination (synthetical
influence of the understanding on the internal sense), which I have
named figurative synthesis.
This we can indeed always perceive in ourselves. We cannot cogitate a
geometrical line without drawing it in thought, nor a circle without
describing it, nor represent the three dimensions of space without
drawing three lines from the same point perpendicular to one another. We
cannot even cogitate time, unless, in drawing a straight line (which is
to serve as the external figurative representation of time), we fix
our attention on the act of the synthesis of the manifold, whereby we
determine successively the internal sense, and thus attend also to the
succession of this determination. Motion as an act of the subject (not
as a determination of an object),* consequently the synthesis of the
manifold in space, if we make abstraction of space and attend merely to
the act by which we determine the internal sense according to its form,
is that which produces the conception of succession. The understanding,
therefore, does by no means find in the internal sense any such
synthesis of the manifold, but produces it, in that it affects this
sense. At the same time, how "I who think" is distinct from the "I"
which intuites itself (other modes of intuition being cogitable as at
least possible), and yet one and the same with this latter as the same
subject; how, therefore, I am able to say: "I, as an intelligence and
thinking subject, cognize myself as an object thought, so far as I am,
moreover, given to myself in intuition--only, like other phenomena, not
as I am in myself, and as considered by the understanding, but merely as
I appear"--is a question that has in it neither more nor less difficulty
than the question--"How can I be an object to myself?" or this--"How I
can be an object of my own intuition and internal perceptions?" But that
such must be the fact, if we admit that space is merely a pure form
of the phenomena of external sense, can be clearly proved by the
consideration that we cannot represent time, which is not an object of
external intuition, in any other way than under the image of a line,
which we draw in thought, a mode of representation without which we
could not cognize the unity of its dimension, and also that we are
necessitated to take our determination of periods of time, or of points
of time, for all our internal perceptions from the changes which
we perceive in outward things. It follows that we must arrange the
determinations of the internal sense, as phenomena in time, exactly in
the same manner as we arrange those of the external senses in space. And
consequently, if we grant, respecting this latter, that by means of them
we know objects only in so far as we are affected externally, we must
also confess, with regard to the internal sense, that by means of it we
intuite ourselves only as we are internally affected by ourselves; in
other words, as regards internal intuition, we cognize our own subject
only as phenomenon, and not as it is in itself.
SS 21.
On the other hand, in the transcendental synthesis of the manifold
content of representations, consequently in the synthetical unity of
apperception, I am conscious of myself, not as I appear to myself,
nor as I am in myself, but only that "I am." This representation is a
thought, not an intuition. Now, as in order to cognize ourselves, in
addition to the act of thinking, which subjects the manifold of every
possible intuition to the unity of apperception, there is necessary a
determinate mode of intuition, whereby this manifold is given; although
my own existence is certainly not mere phenomenon (much less mere
illusion), the determination of my existence* Can only take place
conformably to the form of the internal sense, according to the
particular mode in which the manifold which I conjoin is given in
internal intuition, and I have therefore no knowledge of myself as I am,
but merely as I appear to myself. The consciousness of self is thus
very far from a knowledge of self, in which I do not use the categories,
whereby I cogitate an object, by means of the conjunction of the
manifold in one apperception. In the same way as I require, for the sake
of the cognition of an object distinct from myself, not only the thought
of an object in general (in the category), but also an intuition
by which to determine that general conception, in the same way do I
require, in order to the cognition of myself, not only the consciousness
of myself or the thought that I think myself, but in addition an
intuition of the manifold in myself, by which to determine this thought.
It is true that I exist as an intelligence which is conscious only of
its faculty of conjunction or synthesis, but subjected in relation to
the manifold which this intelligence has to conjoin to a limitative
conjunction called the internal sense. My intelligence (that is, I) can
render that conjunction or synthesis perceptible only according to
the relations of time, which are quite beyond the proper sphere of the
conceptions of the understanding and consequently cognize itself in
respect to an intuition (which cannot possibly be intellectual, nor
given by the understanding), only as it appears to itself, and not as it
would cognize itself, if its intuition were intellectual.
SS 22. Transcendental Deduction of the universally possible employment
in experience of the Pure Conceptions of the Understanding.
In the metaphysical deduction, the a priori origin of categories was
proved by their complete accordance with the general logical of thought;
in the transcendental deduction was exhibited the possibility of the
categories as a priori cognitions of objects of an intuition in general
(SS 16 and 17).At present we are about to explain the possibility of
cognizing, a priori, by means of the categories, all objects which can
possibly be presented to our senses, not, indeed, according to the form
of their intuition, but according to the laws of their conjunction or
synthesis, and thus, as it were, of prescribing laws to nature and even
of rendering nature possible. For if the categories were inadequate
to this task, it would not be evident to us why everything that is
presented to our senses must be subject to those laws which have an a
priori origin in the understanding itself.
I premise that by the term synthesis of apprehension I understand
the combination of the manifold in an empirical intuition, whereby
perception, that is, empirical consciousness of the intuition (as
phenomenon), is possible.
We have a priori forms of the external and internal sensuous intuition
in the representations of space and time, and to these must the
synthesis of apprehension of the manifold in a phenomenon be always
comformable, because the synthesis itself can only take place according
to these forms. But space and time are not merely forms of sensuous
intuition, but intuitions themselves (which contain a manifold), and
therefore contain a priori the determination of the unity of this
manifold.* (See the Transcendent Aesthetic.) Therefore is unity of the
synthesis of the manifold without or within us, consequently also a
conjunction to which all that is to be represented as determined in
space or time must correspond, given a priori along with (not in) these
intuitions, as the condition of the synthesis of all apprehension
of them. But this synthetical unity can be no other than that of the
conjunction of the manifold of a given intuition in general, in a
primitive act of consciousness, according to the categories, but applied
to our sensuous intuition. Consequently all synthesis, whereby alone
is even perception possible, is subject to the categories. And,
as experience is cognition by means of conjoined perceptions, the
categories are conditions of the possibility of experience and are
therefore valid a priori for all objects of experience.
When, then, for example, I make the empirical intuition of a house by
apprehension of the manifold contained therein into a perception, the
necessary unity of space and of my external sensuous intuition lies
at the foundation of this act, and I, as it were, draw the form of the
house conformably to this synthetical unity of the manifold in space.
But this very synthetical unity remains, even when I abstract the form
of space, and has its seat in the understanding, and is in fact the
category of the synthesis of the h*mogeneous in an intuition; that is
to say, the category of quantity, to which the aforesaid synthesis of
apprehension, that is, the perception, must be completely conformable.
To take another example, when I perceive the freezing of water, I
apprehend two states (fluidity and solidity), which, as such, stand
toward each other mutually in a relation of time. But in the time, which
I place as an internal intuition, at the foundation of this phenomenon,
I represent to myself synthetical unity of the manifold, without which
the aforesaid relation could not be given in an intuition as determined
(in regard to the succession of time). Now this synthetical unity,
as the a priori condition under which I conjoin the manifold of an
intuition, is, if I make abstraction of the permanent form of my
internal intuition (that is to say, of time), the category of cause, by
means of which, when applied to my sensibility, I determine everything
that occurs according to relations of time. Consequently apprehension in
such an event, and the event itself, as far as regards the possibility
of its perception, stands under the conception of the relation of cause
and effect: and so in all other cases.
Categories are conceptions which prescribe laws a priori to phenomena,
consequently to nature as the complex of all phenomena (natura
materialiter spectata). And now the question arises--inasmuch as these
categories are not derived from nature, and do not regulate themselves
according to her as their model (for in that case they would be
empirical)--how it is conceivable that nature must regulate herself
according to them, in other words, how the categories can determine a
priori the synthesis of the manifold of nature, and yet not derive their
origin from her. The following is the solution of this enigma.
It is not in the least more difficult to conceive how the laws of the
phenomena of nature must harmonize with the understanding and with its a
priori form--that is, its faculty of conjoining the manifold--than it
is to understand how the phenomena themselves must correspond with the
a priori form of our sensuous intuition. For laws do not exist in the
phenomena any more than the phenomena exist as things in themselves.
Laws do not exist except by relation to the subject in which the
phenomena inhere, in so far as it possesses understanding, just as
phenomena have no existence except by relation to the same existing
subject in so far as it has senses. To things as things in themselves,
conformability to law must necessarily belong independently of an
understanding to cognize them. But phenomena are only representations
of things which are utterly unknown in respect to what they are in
themselves. But as mere representations, they stand under no law of
conjunction except that which the conjoining faculty prescribes. Now
that which conjoins the manifold of sensuous intuition is imagination,
a mental act to which understanding contributes unity of intellectual
synthesis, and sensibility, manifoldness of apprehension. Now as all
possible perception depends on the synthesis of apprehension, and this
empirical synthesis itself on the transcendental, consequently on the
categories, it is evident that all possible perceptions, and therefore
everything that can attain to empirical consciousness, that is, all
phenomena of nature, must, as regards their conjunction, be subject to
the categories. And nature (considered merely as nature in general)
is dependent on them, as the original ground of her necessary
conformability to law (as natura formaliter spectata). But the pure
faculty (of the understanding) of prescribing laws a priori to phenomena
by means of mere categories, is not competent to enounce other or more
laws than those on which a nature in general, as a conformability to law
of phenomena of space and time, depends. Particular laws, inasmuch
as they concern empirically determined phenomena, cannot be entirely
deduced from pure laws, although they all stand under them. Experience
must be superadded in order to know these particular laws; but in regard
to experience in general, and everything that can be cognized as an
object thereof, these a priori laws are our only rule and guide.