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The Critique of Pure Reason by Immanuel Kant

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(b) Space is nothing else than the form of all phenomena of the
external sense, that is, the subjective condition of the
sensibility, under which alone external intuition is possible. Now,
because the receptivity or capacity of the subject to be affected by
objects necessarily antecedes all intuitions of these objects, it is
easily understood how the form of all phenomena can be given in the
mind previous to all actual perceptions, therefore a priori, and how
it, as a pure intuition, in which all objects must be determined,
can contain principles of the relations of these objects prior to
all experience.

It is therefore from the human point of view only that we can
speak of space, extended objects, etc. If we depart from the
subjective condition, under which alone we can obtain external
intuition, or, in other words, by means of which we are affected by
objects, the representation of space has no meaning whatsoever. This
predicate is only applicable to things in so far as they appear to
us, that is, are objects of sensibility. The constant form of this
receptivity, which we call sensibility, is a necessary condition of
all relations in which objects can be intuited as existing without
us, and when abstraction of these objects is made, is a pure intuition,
to which we give the name of space. It is clear that we cannot make
the special conditions of sensibility into conditions of the possibility
of things, but only of the possibility of their existence as far as
they are phenomena. And so we may correctly say that space contains
all which can appear to us externally, but not all things considered
as things in themselves, be they intuited or not, or by whatsoever
subject one will. As to the intuitions of other thinking beings, we
cannot judge whether they are or are not bound by the same
conditions which limit our own intuition, and which for us are
universally valid. If we join the limitation of a judgement to the
conception of the subject, then the judgement will possess
unconditioned validity. For example, the proposition, "All objects
are beside each other in space," is valid only under the limitation
that these things are taken as objects of our sensuous intuition. But
if I join the condition to the conception and say, "All things, as
external phenomena, are beside each other in space," then the rule
is valid universally, and without any limitation. Our expositions,
consequently, teach the reality (i.e., the objective validity) of
space in regard of all which can be presented to us externally as
object, and at the same time also the ideality of space in regard to
objects when they are considered by means of reason as things in
themselves, that is, without reference to the constitution of our
sensibility. We maintain, therefore, the empirical reality of space
in regard to all possible external experience, although we must admit
its transcendental ideality; in other words, that it is nothing, so
soon as we withdraw the condition upon which the possibility of all
experience depends and look upon space as something that belongs to
things in themselves.

But, with the exception of space, there is no representation,
subjective and referring to something external to us, which could
be called objective a priori. For there are no other subjective
representations from which we can deduce synthetical propositions a
priori, as we can from the intuition of space. (See SS 3.)
Therefore, to speak accurately, no ideality whatever belongs to these,
although they agree in this respect with the representation of
space, that they belong merely to the subjective nature of the mode
of sensuous perception; such a mode, for example, as that of sight,
of hearing, and of feeling, by means of the sensations of colour,
sound, and heat, but which, because they are only sensations and not
intuitions, do not of themselves give us the cognition of any
object, least of all, an a priori cognition. My purpose, in the
above remark, is merely this: to guard any one against illustrating
the asserted ideality of space by examples quite insufficient, for
example, by colour, taste, etc.; for these must be contemplated not
as properties of things, but only as changes in the subject, changes
which may be different in different men. For, in such a case, that
which is originally a mere phenomenon, a rose, for example, is taken
by the empirical understanding for a thing in itself, though to
every different eye, in respect of its colour, it may appear
different. On the contrary, the transcendental conception of phenomena
in space is a critical admonition, that, in general, nothing which
is intuited in space is a thing in itself, and that space is not a
form which belongs as a property to things; but that objects are quite
unknown to us in themselves, and what we call outward objects, are
nothing else but mere representations of our sensibility, whose form
is space, but whose real correlate, the thing in itself, is not
known by means of these representations, nor ever can be, but
respecting which, in experience, no inquiry is ever made.


SS 5. Metaphysical Exposition of this Conception.

1. Time is not an empirical conception. For neither coexistence
nor succession would be perceived by us, if the representation of time
did not exist as a foundation a priori. Without this presupposition
we could not represent to ourselves that things exist together at one
and the same time, or at different times, that is, contemporaneously,
or in succession.

2. Time is a necessary representation, lying at the foundation of
all our intuitions. With regard to phenomena in general, we cannot
think away time from them, and represent them to ourselves as out of
and unconnected with time, but we can quite well represent to
ourselves time void of phenomena. Time is therefore given a priori.
In it alone is all reality of phenomena possible. These may all be
annihilated in thought, but time itself, as the universal condition
of their possibility, cannot be so annulled.

3. On this necessity a priori is also founded the possibility of
apodeictic principles of the relations of time, or axioms of time in
general, such as: "Time has only one dimension," "Different times
are not coexistent but successive" (as different spaces are not
successive but coexistent). These principles cannot be derived from
experience, for it would give neither strict universality, nor
apodeictic certainty. We should only be able to say, "so common
experience teaches us," but not "it must be so." They are valid as
rules, through which, in general, experience is possible; and they
instruct us respecting experience, and not by means of it.

4. Time is not a discursive, or as it is called, general conception,
but a pure form of the sensuous intuition. Different times are
merely parts of one and the same time. But the representation which
can only be given by a single object is an intuition. Besides, the
proposition that different times cannot be coexistent could not be
derived from a general conception. For this proposition is
synthetical, and therefore cannot spring out of conceptions alone.
It is therefore contained immediately in the intuition and
representation of time.

5. The infinity of time signifies nothing more than that every
determined quantity of time is possible only through limitations of
one time lying at the foundation. Consequently, the original
representation, time, must be given as unlimited. But as the
determinate representation of the parts of time and of every
quantity of an object can only be obtained by limitation, the complete
representation of time must not be furnished by means of
conceptions, for these contain only partial representations.
Conceptions, on the contrary, must have immediate intuition for
their basis.

SS 6 Transcendental Exposition of the Conception of Time.

I may here refer to what is said above (SS 5, 3), where, for or sake
of brevity, I have placed under the head of metaphysical exposition,
that which is properly transcendental. Here I shall add that the
conception of change, and with it the conception of motion, as
change of place, is possible only through and in the representation
of time; that if this representation were not an intuition (internal)
a priori, no conception, of whatever kind, could render comprehensible
the possibility of change, in other words, of a conjunction of
contradictorily opposed predicates in one and the same object, for
example, the presence of a thing in a place and the non-presence of
the same thing in the same place. It is only in time that it is
possible to meet with two contradictorily opposed determinations in
one thing, that is, after each other. Thus our conception of time
explains the possibility of so much synthetical knowledge a priori,
as is exhibited in the general doctrine of motion, which is not a
little fruitful.

SS 7. Conclusions from the above Conceptions.

(a) Time is not something which subsists of itself, or which inheres
in things as an objective determination, and therefore remains, when
abstraction is made of the subjective conditions of the intuition of
things. For in the former case, it would be something real, yet
without presenting to any power of perception any real object. In
the latter case, as an order or determination inherent in things
themselves, it could not be antecedent to things, as their
condition, nor discerned or intuited by means of synthetical
propositions a priori. But all this is quite possible when we regard
time as merely the subjective condition under which all our intuitions
take place. For in that case, this form of the inward intuition can
be represented prior to the objects, and consequently a priori.

(b) Time is nothing else than the form of the internal sense, that
is, of the intuitions of self and of our internal state. For time
cannot be any determination of outward phenomena. It has to do neither
with shape nor position; on the contrary, it determines the relation
of representations in our internal state. And precisely because this
internal intuition presents to us no shape or form, we endeavour to
supply this want by analogies, and represent the course of time by
a line progressing to infinity, the content of which constitutes a
series which is only of one dimension; and we conclude from the
properties of this line as to all the properties of time, with this
single exception, that the parts of the line are coexistent, whilst
those of time are successive. From this it is clear also that the
representation of time is itself an intuition, because all its
relations can be expressed in an external intuition.

(c) Time is the formal condition a priori of all phenomena whatsoever.
Space, as the pure form of external intuition, is limited as a
condition a priori to external phenomena alone. On the other hand,
because all representations, whether they have or have not external
things for their objects, still in themselves, as determinations of the
mind, belong to our internal state; and because this internal state is
subject to the formal condition of the internal intuition, that is, to
time--time is a condition a priori of all phenomena whatsoever--the
immediate condition of all internal, and thereby the mediate condition
of all external phenomena. If I can say a priori, "All outward
phenomena are in space, and determined a priori according to the
relations of space," I can also, from the principle of the internal
sense, affirm universally, "All phenomena in general, that is, all
objects of the senses, are in time and stand necessarily in relations
of time."

If we abstract our internal intuition of ourselves and all external
intuitions, possible only by virtue of this internal intuition and
presented to us by our faculty of representation, and consequently take
objects as they are in themselves, then time is nothing. It is only of
objective validity in regard to phenomena, because these are things
which we regard as objects of our senses. It no longer objective we,
make abstraction of the sensuousness of our intuition, in other words,
of that mode of representation which is peculiar to us, and speak of
things in general. Time is therefore merely a subjective condition of
our (human) intuition (which is always sensuous, that is, so far as we
are affected by objects), and in itself, independently of the mind or
subject, is nothing. Nevertheless, in respect of all phenomena,
consequently of all things which come within the sphere of our
experience, it is necessarily objective. We cannot say, "All things are
in time," because in this conception of things in general, we abstract
and make no mention of any sort of intuition of things. But this is the
proper condition under which time belongs to our representation of
objects. If we add the condition to the conception, and say, "All
things, as phenomena, that is, objects of sensuous intuition, are in
time," then the proposition has its sound objective validity and
universality a priori.

What we have now set forth teaches, therefore, the empirical reality
of time; that is, its objective validity in reference to all objects
which can ever be presented to our senses. And as our intuition is
always sensuous, no object ever can be presented to us in
experience, which does not come under the conditions of time. On the
other hand, we deny to time all claim to absolute reality; that is,
we deny that it, without having regard to the form of our sensuous
intuition, absolutely inheres in things as a condition or property.
Such properties as belong to objects as things in themselves never
can be presented to us through the medium of the senses. Herein
consists, therefore, the transcendental ideality of time, according
to which, if we abstract the subjective conditions of sensuous intuition,
it is nothing, and cannot be reckoned as subsisting or inhering in
objects as things in themselves, independently of its relation to
our intuition. This ideality, like that of space, is not to be
proved or illustrated by fallacious analogies with sensations, for
this reason--that in such arguments or illustrations, we make the
presupposition that the phenomenon, in which such and such
predicates inhere, has objective reality, while in this case we can
only find such an objective reality as is itself empirical, that is,
regards the object as a mere phenomenon. In reference to this subject,
see the remark in Section I (SS 4)

SS 8. Elucidation.

Against this theory, which grants empirical reality to time, but denies
to it absolute and transcendental reality, I have heard from
intelligent men an objection so unanimously urged that I conclude that
it must naturally present itself to every reader to whom these
considerations are novel. It runs thus: "Changes are real" (this the
continual change in our own representations demonstrates, even though
the existence of all external phenomena, together with their changes,
is denied). Now, changes are only possible in time, and therefore time
must be something real. But there is no difficulty in answering this. I
grant the whole argument. Time, no doubt, is something real, that is,
it is the real form of our internal intuition. It therefore has
subjective reality, in reference to our internal experience, that is, I
have really the representation of time and of my determinations
therein. Time, therefore, is not to be regarded as an object, but as
the mode of representation of myself as an object. But if I could
intuite myself, or be intuited by another being, without this condition
of sensibility, then those very determinations which we now represent
to ourselves as changes, would present to us a knowledge in which the
representation of time, and consequently of change, would not appear.
The empirical reality of time, therefore, remains, as the condition of
all our experience. But absolute reality, according to what has been
said above, cannot be granted it. Time is nothing but the form of our
internal intuition.* If we take away from it the special condition of
our sensibility, the conception of time also vanishes; and it inheres
not in the objects themselves, but solely in the subject (or mind)
which intuites them.

[*Footnote: I can indeed say "my representations follow one another,
or are successive"; but this means only that we are conscious of them
as in a succession, that is, according to the form of the internal
sense. Time, therefore, is not a thing in itself, nor is it any objective
determination pertaining to, or inherent in things.]

But the reason why this objection is so unanimously brought
against our doctrine of time, and that too by disputants who cannot
start any intelligible arguments against the doctrine of the
ideality of space, is this--they have no hope of demonstrating
apodeictically the absolute reality of space, because the doctrine
of idealism is against them, according to which the reality of
external objects is not capable of any strict proof. On the other
hand, the reality of the object of our internal sense (that is, myself
and my internal state) is clear immediately through consciousness.
The former--external objects in space--might be a mere delusion, but
the latter--the object of my internal perception--is undeniably real.
They do not, however, reflect that both, without question of their
reality as representations, belong only to the genus phenomenon, which
has always two aspects, the one, the object considered as a thing in
itself, without regard to the mode of intuiting it, and the nature
of which remains for this very reason problematical, the other, the
form of our intuition of the object, which must be sought not in the
object as a thing in itself, but in the subject to which it appears--
which form of intuition nevertheless belongs really and necessarily
to the phenomenal object.

Time and space are, therefore, two sources of knowledge, from which,
a priori, various synthetical cognitions can be drawn. Of this we find
a striking example in the cognitions of space and its relations, which
form the foundation of pure mathematics. They are the two pure forms
of all intuitions, and thereby make synthetical propositions a
priori possible. But these sources of knowledge being merely
conditions of our sensibility, do therefore, and as such, strictly
determine their own range and purpose, in that they do not and
cannot present objects as things in themselves, but are applicable
to them solely in so far as they are considered as sensuous phenomena.
The sphere of phenomena is the only sphere of their validity, and if
we venture out of this, no further objective use can be made of
them. For the rest, this formal reality of time and space leaves the
validity of our empirical knowledge unshaken; for our certainty in
that respect is equally firm, whether these forms necessarily inhere
in the things themselves, or only in our intuitions of them. On the
other hand, those who maintain the absolute reality of time and space,
whether as essentially subsisting, or only inhering, as modifications,
in things, must find themselves at utter variance with the
principles of experience itself. For, if they decide for the first
view, and make space and time into substances, this being the side
taken by mathematical natural philosophers, they must admit two
self-subsisting nonentities, infinite and eternal, which exist (yet
without there being anything real) for the purpose of containing in
themselves everything that is real. If they adopt the second view of
inherence, which is preferred by some metaphysical natural
philosophers, and regard space and time as relations (contiguity in
space or succession in time), abstracted from experience, though
represented confusedly in this state of separation, they find
themselves in that case necessitated to deny the validity of
mathematical doctrines a priori in reference to real things (for
example, in space)--at all events their apodeictic certainty. For such
certainty cannot be found in an a posteriori proposition; and the
conceptions a priori of space and time are, according to this opinion,
mere creations of the imagination, having their source really in
experience, inasmuch as, out of relations abstracted from
experience, imagination has made up something which contains,
indeed, general statements of these relations, yet of which no
application can be made without the restrictions attached thereto by
nature. The former of these parties gains this advantage, that they
keep the sphere of phenomena free for mathematical science. On the
other hand, these very conditions (space and time) embarrass them
greatly, when the understanding endeavours to pass the limits of
that sphere. The latter has, indeed, this advantage, that the
representations of space and time do not come in their way when they
wish to judge of objects, not as phenomena, but merely in their
relation to the understanding. Devoid, however, of a true and
objectively valid a priori intuition, they can neither furnish any
basis for the possibility of mathematical cognitions a priori, nor
bring the propositions of experience into necessary accordance with
those of mathematics. In our theory of the true nature of these two
original forms of the sensibility, both difficulties are surmounted.

In conclusion, that transcendental aesthetic cannot contain any more
than these two elements--space and time, is sufficiently obvious
from the fact that all other conceptions appertaining to
sensibility, even that of motion, which unites in itself both
elements, presuppose something empirical. Motion, for example,
presupposes the perception of something movable. But space
considered in itself contains nothing movable, consequently motion
must be something which is found in space only through experience--
in other words, an empirical datum. In like manner, transcendental
aesthetic cannot number the conception of change among its data a
priori; for time itself does not change, but only something which is
in time. To acquire the conception of change, therefore, the
perception of some existing object and of the succession of its
determinations, in one word, experience, is necessary.

SS 9. General Remarks on Transcendental Aesthetic.

I. In order to prevent any misunderstanding, it will be requisite,
in the first place, to recapitulate, as clearly as possible, what
our opinion is with respect to the fundamental nature of our
sensuous cognition in general. We have intended, then, to say that
all our intuition is nothing but the representation of phenomena; that
the things which we intuite, are not in themselves the same as our
representations of them in intuition, nor are their relations in
themselves so constituted as they appear to us; and that if we take
away the subject, or even only the subjective constitution of our
senses in general, then not only the nature and relations of objects
in space and time, but even space and time themselves disappear; and
that these, as phenomena, cannot exist in themselves, but only in
us. What may be the nature of objects considered as things in
themselves and without reference to the receptivity of our sensibility
is quite unknown to us. We know nothing more than our mode of
perceiving them, which is peculiar to us, and which, though not of
necessity pertaining to every animated being, is so to the whole human
race. With this alone we have to do. Space and time are the pure forms
thereof; sensation the matter. The former alone can we cognize a
priori, that is, antecedent to all actual perception; and for this
reason such cognition is called pure intuition. The latter is that
in our cognition which is called cognition a posteriori, that is,
empirical intuition. The former appertain absolutely and necessarily
to our sensibility, of whatsoever kind our sensations may be; the
latter may be of very diversified character. Supposing that we
should carry our empirical intuition even to the very highest degree
of clearness, we should not thereby advance one step nearer to a
knowledge of the constitution of objects as things in themselves.
For we could only, at best, arrive at a complete cognition of our
own mode of intuition, that is of our sensibility, and this always
under the conditions originally attaching to the subject, namely,
the conditions of space and time; while the question: "What are
objects considered as things in themselves?" remains unanswerable even
after the most thorough examination of the phenomenal world.

To say, then, that all our sensibility is nothing but the confused
representation of things containing exclusively that which belongs
to them as things in themselves, and this under an accumulation of
characteristic marks and partial representations which we cannot
distinguish in consciousness, is a falsification of the conception
of sensibility and phenomenization, which renders our whole doctrine
thereof empty and useless. The difference between a confused and a
clear representation is merely logical and has nothing to do with
content. No doubt the conception of right, as employed by a sound
understanding, contains all that the most subtle investigation could
unfold from it, although, in the ordinary practical use of the word,
we are not conscious of the manifold representations comprised in
the conception. But we cannot for this reason assert that the ordinary
conception is a sensuous one, containing a mere phenomenon, for
right cannot appear as a phenomenon; but the conception of it lies
in the understanding, and represents a property (the moral property)
of actions, which belongs to them in themselves. On the other hand,
the representation in intuition of a body contains nothing which could
belong to an object considered as a thing in itself, but merely the
phenomenon or appearance of something, and the mode in which we are
affected by that appearance; and this receptivity of our faculty of
cognition is called sensibility, and remains toto caelo different from
the cognition of an object in itself, even though we should examine
the content of the phenomenon to the very bottom.

It must be admitted that the Leibnitz-Wolfian philosophy has
assigned an entirely erroneous point of view to all investigations
into the nature and origin of our cognitions, inasmuch as it regards
the distinction between the sensuous and the intellectual as merely
logical, whereas it is plainly transcendental, and concerns not merely
the clearness or obscurity, but the content and origin of both. For
the faculty of sensibility not only does not present us with an
indistinct and confused cognition of objects as things in
themselves, but, in fact, gives us no knowledge of these at all. On
the contrary, so soon as we abstract in thought our own subjective
nature, the object represented, with the properties ascribed to it
by sensuous intuition, entirely disappears, because it was only this
subjective nature that determined the form of the object as a

In phenomena, we commonly, indeed, distinguish that which
essentially belongs to the intuition of them, and is valid for the
sensuous faculty of every human being, from that which belongs to
the same intuition accidentally, as valid not for the sensuous faculty
in general, but for a particular state or organization of this or that
sense. Accordingly, we are accustomed to say that the former is a
cognition which represents the object itself, whilst the latter
presents only a particular appearance or phenomenon thereof. This
distinction, however, is only empirical. If we stop here (as is
usual), and do not regard the empirical intuition as itself a mere
phenomenon (as we ought to do), in which nothing that can appertain
to a thing in itself is to be found, our transcendental distinction
is lost, and we believe that we cognize objects as things in
themselves, although in the whole range of the sensuous world,
investigate the nature of its objects as profoundly as we may, we have
to do with nothing but phenomena. Thus, we call the rainbow a mere
appearance of phenomenon in a sunny shower, and the rain, the
reality or thing in itself; and this is right enough, if we understand
the latter conception in a merely physical sense, that is, as that
which in universal experience, and under whatever conditions of
sensuous perception, is known in intuition to be so and so determined,
and not otherwise. But if we consider this empirical datum
generally, and inquire, without reference to its accordance with all
our senses, whether there can be discovered in it aught which
represents an object as a thing in itself (the raindrops of course
are not such, for they are, as phenomena, empirical objects), the question
of the relation of the representation to the object is transcendental;
and not only are the raindrops mere phenomena, but even their circular
form, nay, the space itself through which they fall, is nothing in
itself, but both are mere modifications or fundamental dispositions
of our sensuous intuition, whilst the transcendental object remains
for us utterly unknown.

The second important concern of our aesthetic is that it does not
obtain favour merely as a plausible hypothesis, but possess as
undoubted a character of certainty as can be demanded of any theory
which is to serve for an organon. In order fully to convince the
reader of this certainty, we shall select a case which will serve to
make its validity apparent, and also to illustrate what has been
said in SS 3.

Suppose, then, that space and time are in themselves objective,
and conditions of the--possibility of objects as things in themselves.
In the first place, it is evident that both present us, with very many
apodeictic and synthetic propositions a priori, but especially
space--and for this reason we shall prefer it for investigation at
present. As the propositions of geometry are cognized synthetically
a priori, and with apodeictic certainty, I inquire: Whence do you
obtain propositions of this kind, and on what basis does the
understanding rest, in order to arrive at such absolutely necessary
and universally valid truths?

There is no other way than through intuitions or conceptions, as
such; and these are given either a priori or a posteriori. The latter,
namely, empirical conceptions, together with the empirical intuition
on which they are founded, cannot afford any synthetical
proposition, except such as is itself also empirical, that is, a
proposition of experience. But an empirical proposition cannot possess
the qualities of necessity and absolute universality, which,
nevertheless, are the characteristics of all geometrical propositions.
As to the first and only means to arrive at such cognitions, namely,
through mere conceptions or intuitions a priori, it is quite clear
that from mere conceptions no synthetical cognitions, but only
analytical ones, can be obtained. Take, for example, the
proposition: "Two straight lines cannot enclose a space, and with
these alone no figure is possible," and try to deduce it from the
conception of a straight line and the number two; or take the
proposition: "It is possible to construct a figure with three straight
lines," and endeavour, in like manner, to deduce it from the mere
conception of a straight line and the number three. All your
endeavours are in vain, and you find yourself forced to have
recourse to intuition, as, in fact, geometry always does. You
therefore give yourself an object in intuition. But of what kind is
this intuition? Is it a pure a priori, or is it an empirical
intuition? If the latter, then neither an universally valid, much less
an apodeictic proposition can arise from it, for experience never
can give us any such proposition. You must, therefore, give yourself
an object a priori in intuition, and upon that ground your synthetical
proposition. Now if there did not exist within you a faculty of
intuition a priori; if this subjective condition were not in respect
to its form also the universal condition a priori under which alone
the object of this external intuition is itself possible; if the
object (that is, the triangle) were something in itself, without
relation to you the subject; how could you affirm that that which lies
necessarily in your subjective conditions in order to construct a
triangle, must also necessarily belong to the triangle in itself?
For to your conceptions of three lines, you could not add anything
new (that is, the figure); which, therefore, must necessarily be found
in the object, because the object is given before your cognition,
and not by means of it. If, therefore, space (and time also) were
not a mere form of your intuition, which contains conditions a priori,
under which alone things can become external objects for you, and
without which subjective conditions the objects are in themselves
nothing, you could not construct any synthetical proposition
whatsoever regarding external objects. It is therefore not merely
possible or probable, but indubitably certain, that space and time,
as the necessary conditions of all our external and internal
experience, are merely subjective conditions of all our intuitions,
in relation to which all objects are therefore mere phenomena, and
not things in themselves, presented to us in this particular manner.
And for this reason, in respect to the form of phenomena, much may
be said a priori, whilst of the thing in itself, which may lie at the
foundation of these phenomena, it is impossible to say anything.

II. In confirmation of this theory of the ideality of the external
as well as internal sense, consequently of all objects of sense, as
mere phenomena, we may especially remark that all in our cognition
that belongs to intuition contains nothing more than mere relations.
(The feelings of pain and pleasure, and the will, which are not
cognitions, are excepted.) The relations, to wit, of place in an
intuition (extension), change of place (motion), and laws according
to which this change is determined (moving forces). That, however,
which is present in this or that place, or any operation going on,
or result taking place in the things themselves, with the exception
of change of place, is not given to us by intuition. Now by means of
mere relations, a thing cannot be known in itself; and it may therefore
be fairly concluded, that, as through the external sense nothing but
mere representations of relations are given us, the said external
sense in its representation can contain only the relation of the
object to the subject, but not the essential nature of the object as
a thing in itself.

The same is the case with the internal intuition, not only
because, in the internal intuition, the representation of the external
senses constitutes the material with which the mind is occupied; but
because time, in which we place, and which itself antecedes the
consciousness of, these representations in experience, and which, as
the formal condition of the mode according to which objects are placed
in the mind, lies at the foundation of them, contains relations of
the successive, the coexistent, and of that which always must be
coexistent with succession, the permanent. Now that which, as
representation, can antecede every exercise of thought (of an object),
is intuition; and when it contains nothing but relations, it is the
form of the intuition, which, as it presents us with no
representation, except in so far as something is placed in the mind,
can be nothing else than the mode in which the mind is affected by
its own activity, to wit--its presenting to itself representations,
consequently the mode in which the mind is affected by itself; that
is, it can be nothing but an internal sense in respect to its form.
Everything that is represented through the medium of sense is so far
phenomenal; consequently, we must either refuse altogether to admit
an internal sense, or the subject, which is the object of that sense,
could only be represented by it as phenomenon, and not as it would
judge of itself, if its intuition were pure spontaneous activity, that
is, were intellectual. The difficulty here lies wholly in the
question: How can the subject have an internal intuition of itself?
But this difficulty is common to every theory. The consciousness of
self (apperception) is the simple representation of the "ego"; and
if by means of that representation alone, all the manifold
representations in the subject were spontaneously given, then our
internal intuition would be intellectual. This consciousness in man
requires an internal perception of the manifold representations
which are previously given in the subject; and the manner in which
these representations are given in the mind without spontaneity, must,
on account of this difference (the want of spontaneity), be called
sensibility. If the faculty of self-consciousness is to apprehend what
lies in the mind, it must all act that and can in this way alone
produce an intuition of self. But the form of this intuition, which
lies in the original constitution of the mind, determines, in the
representation of time, the manner in which the manifold
representations are to combine themselves in the mind; since the
subject intuites itself, not as it would represent itself
immediately and spontaneously, but according to the manner in which
the mind is internally affected, consequently, as it appears, and
not as it is.

III. When we say that the intuition of external objects, and also
the self-intuition of the subject, represent both, objects and
subject, in space and time, as they affect our senses, that is, as
they appear--this is by no means equivalent to asserting that these
objects are mere illusory appearances. For when we speak of things
as phenomena, the objects, nay, even the properties which we ascribe
to them, are looked upon as really given; only that, in so far as this
or that property depends upon the mode of intuition of the subject,
in the relation of the given object to the subject, the object as
phenomenon is to be distinguished from the object as a thing in
itself. Thus I do not say that bodies seem or appear to be external
to me, or that my soul seems merely to be given in my self-consciousness,
although I maintain that the properties of space and time, in
conformity to which I set both, as the condition of their existence,
abide in my mode of intuition, and not in the objects in themselves.
It would be my own fault, if out of that which I should reckon as
phenomenon, I made mere illusory appearance.* But this will not
happen, because of our principle of the ideality of all sensuous
intuitions. On the contrary, if we ascribe objective reality to
these forms of representation, it becomes impossible to avoid changing
everything into mere appearance. For if we regard space and time as
properties, which must be found in objects as things in themselves,
as sine quibus non of the possibility of their existence, and reflect
on the absurdities in which we then find ourselves involved,
inasmuch as we are compelled to admit the existence of two infinite
things, which are nevertheless not substances, nor anything really
inhering in substances, nay, to admit that they are the necessary
conditions of the existence of all things, and moreover, that they
must continue to exist, although all existing things were annihilated--
we cannot blame the good Berkeley for degrading bodies to mere
illusory appearances. Nay, even our own existence, which would in this
case depend upon the self-existent reality of such a mere nonentity
as time, would necessarily be changed with it into mere appearance--an
absurdity which no one has as yet been guilty of.

[*Footnote: The predicates of the phenomenon can be affixed to the
object itself in relation to our sensuous faculty; for example, the
red colour or the perfume to the rose. But (illusory) appearance never
can be attributed as a predicate to an object, for this very reason,
that it attributes to this object in itself that which belongs to it
only in relation to our sensuous faculty, or to the subject in
general, e.g., the two handles which were formerly ascribed to Saturn.
That which is never to be found in the object itself, but always in
the relation of the object to the subject, and which moreover is
inseparable from our representation of the object, we denominate
phenomenon. Thus the predicates of space and time are rightly
attributed to objects of the senses as such, and in this there is no
illusion. On the contrary, if I ascribe redness of the rose as a thing
in itself, or to Saturn his handles, or extension to all external
objects, considered as things in themselves, without regarding the
determinate relation of these objects to the subject, and without
limiting my judgement to that relation--then, and then only, arises

IV. In natural theology, where we think of an object--God--which
never can be an object of intuition to us, and even to himself can
never be an object of sensuous intuition, we carefully avoid
attributing to his intuition the conditions of space and time--and
intuition all his cognition must be, and not thought, which always
includes limitation. But with what right can we do this if we make
them forms of objects as things in themselves, and such, moreover,
as would continue to exist as a priori conditions of the existence
of things, even though the things themselves were annihilated? For
as conditions of all existence in general, space and time must be
conditions of the existence of the Supreme Being also. But if we do
not thus make them objective forms of all things, there is no other
way left than to make them subjective forms of our mode of
intuition--external and internal; which is called sensuous, because
it is not primitive, that is, is not such as gives in itself the
existence of the object of the intuition (a mode of intuition which,
so far as we can judge, can belong only to the Creator), but is
dependent on the existence of the object, is possible, therefore, only
on condition that the representative faculty of the subject is
affected by the object.

It is, moreover, not necessary that we should limit the mode of
intuition in space and time to the sensuous faculty of man. It may
well be that all finite thinking beings must necessarily in this
respect agree with man (though as to this we cannot decide), but
sensibility does not on account of this universality cease to be
sensibility, for this very reason, that it is a deduced (intuitus
derivativus), and not an original (intuitus originarius), consequently
not an intellectual intuition, and this intuition, as such, for
reasons above mentioned, seems to belong solely to the Supreme
Being, but never to a being dependent, quoad its existence, as well
as its intuition (which its existence determines and limits relatively
to given objects). This latter remark, however, must be taken only
as an illustration, and not as any proof of the truth of our
aesthetical theory.

SS 10. Conclusion of the Transcendental Aesthetic.

We have now completely before us one part of the solution of the
grand general problem of transcendental philosophy, namely, the
question: "How are synthetical propositions a priori possible?" That
is to say, we have shown that we are in possession of pure a priori
intuitions, namely, space and time, in which we find, when in a
judgement a priori we pass out beyond the given conception,
something which is not discoverable in that conception, but is
certainly found a priori in the intuition which corresponds to the
conception, and can be united synthetically with it. But the
judgements which these pure intuitions enable us to make, never
reach farther than to objects of the senses, and are valid only for
objects of possible experience.


INTRODUCTION. Idea of a Transcendental Logic.

I. Of Logic in General.

Our knowledge springs from two main sources in the mind, first of
which is the faculty or power of receiving representations
(receptivity for impressions); the second is the power of cognizing
by means of these representations (spontaneity in the production of
conceptions). Through the first an object is given to us; through
the second, it is, in relation to the representation (which is a
mere determination of the mind), thought. Intuition and conceptions
constitute, therefore, the elements of all our knowledge, so that
neither conceptions without an intuition in some way corresponding
to them, nor intuition without conceptions, can afford us a cognition.
Both are either pure or empirical. They are empirical, when sensation
(which presupposes the actual presence of the object) is contained
in them; and pure, when no sensation is mixed with the representation.
Sensations we may call the matter of sensuous cognition. Pure
intuition consequently contains merely the form under which
something is intuited, and pure conception only the form of the
thought of an object. Only pure intuitions and pure conceptions are
possible a priori; the empirical only a posteriori.

We apply the term sensibility to the receptivity of the mind for
impressions, in so far as it is in some way affected; and, on the
other hand, we call the faculty of spontaneously producing
representations, or the spontaneity of cognition, understanding. Our
nature is so constituted that intuition with us never can be other
than sensuous, that is, it contains only the mode in which we are
affected by objects. On the other hand, the faculty of thinking the
object of sensuous intuition is the understanding. Neither of these
faculties has a preference over the other. Without the sensuous
faculty no object would be given to us, and without the
understanding no object would be thought. Thoughts without content
are void; intuitions without conceptions, blind. Hence it is as
necessary for the mind to make its conceptions sensuous (that is, to
join to them the object in intuition), as to make its intuitions
intelligible (that is, to bring them under conceptions). Neither of
these faculties can exchange its proper function. Understanding cannot
intuite, and the sensuous faculty cannot think. In no other way than
from the united operation of both, can knowledge arise. But no one
ought, on this account, to overlook the difference of the elements
contributed by each; we have rather great reason carefully to separate
and distinguish them. We therefore distinguish the science of the laws
of sensibility, that is, aesthetic, from the science of the laws of
the understanding, that is, logic.

Now, logic in its turn may be considered as twofold--namely, as
logic of the general, or of the particular use of the understanding.
The first contains the absolutely necessary laws of thought, without
which no use whatsoever of the understanding is possible, and gives
laws therefore to the understanding, without regard to the
difference of objects on which it may be employed. The logic of the
particular use of the understanding contains the laws of correct
thinking upon a particular class of objects. The former may be
called elemental logic--the latter, the organon of this or that
particular science. The latter is for the most part employed in the
schools, as a propaedeutic to the sciences, although, indeed,
according to the course of human reason, it is the last thing we
arrive at, when the science has been already matured, and needs only
the finishing touches towards its correction and completion; for our
knowledge of the objects of our attempted science must be tolerably
extensive and complete before we can indicate the laws by which a
science of these objects can be established.

General logic is again either pure or applied. In the former, we
abstract all the empirical conditions under which the understanding
is exercised; for example, the influence of the senses, the play of
the fantasy or imagination, the laws of the memory, the force of habit,
of inclination, etc., consequently also, the sources of prejudice--in
a word, we abstract all causes from which particular cognitions arise,
because these causes regard the understanding under certain
circumstances of its application, and, to the knowledge of them
experience is required. Pure general logic has to do, therefore,
merely with pure a priori principles, and is a canon of
understanding and reason, but only in respect of the formal part of
their use, be the content what it may, empirical or transcendental.
General logic is called applied, when it is directed to the laws of
the use of the understanding, under the subjective empirical
conditions which psychology teaches us. It has therefore empirical
principles, although, at the same time, it is in so far general,
that it applies to the exercise of the understanding, without regard
to the difference of objects. On this account, moreover, it is neither
a canon of the understanding in general, nor an organon of a
particular science, but merely a cathartic of the human understanding.

In general logic, therefore, that part which constitutes pure
logic must be carefully distinguished from that which constitutes
applied (though still general) logic. The former alone is properly
science, although short and dry, as the methodical exposition of an
elemental doctrine of the understanding ought to be. In this,
therefore, logicians must always bear in mind two rules:

1. As general logic, it makes abstraction of all content of the
cognition of the understanding, and of the difference of objects,
and has to do with nothing but the mere form of thought.

2. As pure logic, it has no empirical principles, and consequently
draws nothing (contrary to the common persuasion) from psychology,
which therefore has no influence on the canon of the understanding.
It is a demonstrated doctrine, and everything in it must be certain
completely a priori.

What I called applied logic (contrary to the common acceptation of
this term, according to which it should contain certain exercises
for the scholar, for which pure logic gives the rules), is a
representation of the understanding, and of the rules of its necessary
employment in concreto, that is to say, under the accidental
conditions of the subject, which may either hinder or promote this
employment, and which are all given only empirically. Thus applied
logic treats of attention, its impediments and consequences, of the
origin of error, of the state of doubt, hesitation, conviction,
etc., and to it is related pure general logic in the same way that
pure morality, which contains only the necessary moral laws of a
free will, is related to practical ethics, which considers these
laws under all the impediments of feelings, inclinations, and passions
to which men are more or less subjected, and which never can furnish
us with a true and demonstrated science, because it, as well as
applied logic, requires empirical and psychological principles.

II. Of Transcendental Logic.

General logic, as we have seen, makes abstraction of all content
of cognition, that is, of all relation of cognition to its object,
and regards only the logical form in the relation of cognitions to
each other, that is, the form of thought in general. But as we have
both pure and empirical intuitions (as transcendental aesthetic proves),
in like manner a distinction might be drawn between pure and empirical
thought (of objects). In this case, there would exist a kind of logic,
in which we should not make abstraction of all content of cognition;
for or logic which should comprise merely the laws of pure thought
(of an object), would of course exclude all those cognitions which
were of empirical content. This kind of logic would also examine the
origin of our cognitions of objects, so far as that origin cannot be
ascribed to the objects themselves; while, on the contrary, general
logic has nothing to do with the origin of our cognitions, but contemplates
our representations, be they given primitively a priori in
ourselves, or be they only of empirical origin, solely according to
the laws which the understanding observes in employing them in the
process of thought, in relation to each other. Consequently, general
logic treats of the form of the understanding only, which can be
applied to representations, from whatever source they may have arisen.

And here I shall make a remark, which the reader must bear well in
mind in the course of the following considerations, to wit, that not
every cognition a priori, but only those through which we cognize that
and how certain representations (intuitions or conceptions) are
applied or are possible only a priori; that is to say, the a priori
possibility of cognition and the a priori use of it are
transcendental. Therefore neither is space, nor any a priori
geometrical determination of space, a transcendental Representation,
but only the knowledge that such a representation is not of
empirical origin, and the possibility of its relating to objects of
experience, although itself a priori, can be called transcendental.
So also, the application of space to objects in general would be
transcendental; but if it be limited to objects of sense it is
empirical. Thus, the distinction of the transcendental and empirical
belongs only to the critique of cognitions, and does not concern the
relation of these to their object.

Accordingly, in the expectation that there may perhaps be
conceptions which relate a priori to objects, not as pure or
sensuous intuitions, but merely as acts of pure thought (which are
therefore conceptions, but neither of empirical nor aesthetical
origin)--in this expectation, I say, we form to ourselves, by
anticipation, the idea of a science of pure understanding and rational
cognition, by means of which we may cogitate objects entirely a
priori. A science of this kind, which should determine the origin,
the extent, and the objective validity of such cognitions, must be
called transcendental logic, because it has not, like general logic,
to do with the laws of understanding and reason in relation to
empirical as well as pure rational cognitions without distinction,
but concerns itself with these only in an a priori relation to objects.

III. Of the Division of General Logic into Analytic and Dialectic.

The old question with which people sought to push logicians into a
corner, so that they must either have recourse to pitiful sophisms
or confess their ignorance, and consequently the vanity of their whole
art, is this: "What is truth?" The definition of the word truth, to
wit, "the accordance of the cognition with its object," is presupposed
in the question; but we desire to be told, in the answer to it, what
is the universal and secure criterion of the truth of every cognition.

To know what questions we may reasonably propose is in itself a
strong evidence of sagacity and intelligence. For if a question be
in itself absurd and unsusceptible of a rational answer, it is
attended with the danger--not to mention the shame that falls upon
the person who proposes it--of seducing the unguarded listener into
making absurd answers, and we are presented with the ridiculous spectacle
of one (as the ancients said) "milking the he-goat, and the other
holding a sieve."

If truth consists in the accordance of a cognition with its
object, this object must be, ipso facto, distinguished from all
others; for a cognition is false if it does not accord with the object
to which it relates, although it contains something which may be
affirmed of other objects. Now an universal criterion of truth would
be that which is valid for all cognitions, without distinction of
their objects. But it is evident that since, in the case of such a
criterion, we make abstraction of all the content of a cognition (that
is, of all relation to its object), and truth relates precisely to
this content, it must be utterly absurd to ask for a mark of the truth
of this content of cognition; and that, accordingly, a sufficient,
and at the same time universal, test of truth cannot possibly be found.
As we have already termed the content of a cognition its matter, we
shall say: "Of the truth of our cognitions in respect of their matter,
no universal test can be demanded, because such a demand is

On the other hand, with regard to our cognition in respect of its
mere form (excluding all content), it is equally manifest that
logic, in so far as it exhibits the universal and necessary laws of
the understanding, must in these very laws present us with criteria
of truth. Whatever contradicts these rules is false, because thereby
the understanding is made to contradict its own universal laws of
thought; that is, to contradict itself. These criteria, however, apply
solely to the form of truth, that is, of thought in general, and in
so far they are perfectly accurate, yet not sufficient. For although
a cognition may be perfectly accurate as to logical form, that is,
not self-contradictory, it is notwithstanding quite possible that it
may not stand in agreement with its object. Consequently, the merely
logical criterion of truth, namely, the accordance of a cognition with
the universal and formal laws of understanding and reason, is
nothing more than the conditio sine qua non, or negative condition
of all truth. Farther than this logic cannot go, and the error which
depends not on the form, but on the content of the cognition, it has
no test to discover.

General logic, then, resolves the whole formal business of
understanding and reason into its elements, and exhibits them as
principles of all logical judging of our cognitions. This part of
logic may, therefore, be called analytic, and is at least the negative
test of truth, because all cognitions must first of an be estimated
and tried according to these laws before we proceed to investigate
them in respect of their content, in order to discover whether they
contain positive truth in regard to their object. Because, however,
the mere form of a cognition, accurately as it may accord with logical
laws, is insufficient to supply us with material (objective) truth,
no one, by means of logic alone, can venture to predicate anything
of or decide concerning objects, unless he has obtained, independently
of logic, well-grounded information about them, in order afterwards
to examine, according to logical laws, into the use and connection,
in a cohering whole, of that information, or, what is still better,
merely to test it by them. Notwithstanding, there lies so seductive
a charm in the possession of a specious art like this--an art which
gives to all our cognitions the form of the understanding, although
with respect to the content thereof we may be sadly deficient--that
general logic, which is merely a canon of judgement, has been employed
as an organon for the actual production, or rather for the semblance
of production, of objective assertions, and has thus been grossly
misapplied. Now general logic, in its assumed character of organon,
is called dialectic.

Different as are the significations in which the ancients used
this term for a science or an art, we may safely infer, from their
actual employment of it, that with them it was nothing else than a
logic of illusion--a sophistical art for giving ignorance, nay, even
intentional sophistries, the colouring of truth, in which the
thoroughness of procedure which logic requires was imitated, and their
topic employed to cloak the empty pretensions. Now it may be taken
as a safe and useful warning, that general logic, considered as an
organon, must always be a logic of illusion, that is, be
dialectical, for, as it teaches us nothing whatever respecting the
content of our cognitions, but merely the formal conditions of their
accordance with the understanding, which do not relate to and are
quite indifferent in respect of objects, any attempt to employ it as
an instrument (organon) in order to extend and enlarge the range of
our knowledge must end in mere prating; any one being able to maintain
or oppose, with some appearance of truth, any single assertion

Such instruction is quite unbecoming the dignity of philosophy.
For these reasons we have chosen to denominate this part of logic
dialectic, in the sense of a critique of dialectical illusion, and
we wish the term to be so understood in this place.

IV. Of the Division of Transcendental Logic into Transcendental
Analytic and Dialectic.

In transcendental logic we isolate the understanding (as in
transcendental aesthetic the sensibility) and select from our
cognition merely that part of thought which has its origin in the
understanding alone. The exercise of this pure cognition, however,
depends upon this as its condition, that objects to which it may be
applied be given to us in intuition, for without intuition the whole
of our cognition is without objects, and is therefore quite void. That
part of transcendental logic, then, which treats of the elements of
pure cognition of the understanding, and of the principles without
which no object at all can be thought, is transcendental analytic,
and at the same time a logic of truth. For no cognition can contradict
it, without losing at the same time all content, that is, losing all
reference to an object, and therefore all truth. But because we are
very easily seduced into employing these pure cognitions and
principles of the understanding by themselves, and that even beyond
the boundaries of experience, which yet is the only source whence we
can obtain matter (objects) on which those pure conceptions may be
employed--understanding runs the risk of making, by means of empty
sophisms, a material and objective use of the mere formal principles
of the pure understanding, and of passing judgements on objects
without distinction--objects which are not given to us, nay, perhaps
cannot be given to us in any way. Now, as it ought properly to be only
a canon for judging of the empirical use of the understanding, this
kind of logic is misused when we seek to employ it as an organon of
the universal and unlimited exercise of the understanding, and attempt
with the pure understanding alone to judge synthetically, affirm,
and determine respecting objects in general. In this case the exercise
of the pure understanding becomes dialectical. The second part of
our transcendental logic must therefore be a critique of dialectical
illusion, and this critique we shall term transcendental dialectic--
not meaning it as an art of producing dogmatically such illusion (an
art which is unfortunately too current among the practitioners of
metaphysical juggling), but as a critique of understanding and
reason in regard to their hyperphysical use. This critique will expose
the groundless nature of the pretensions of these two faculties, and
invalidate their claims to the discovery and enlargement of our
cognitions merely by means of transcendental principles, and show that
the proper employment of these faculties is to test the judgements
made by the pure understanding, and to guard it from sophistical




Transcendental analytic is the dissection of the whole of our a priori
knowledge into the elements of the pure cognition of the understanding.
In order to effect our purpose, it is necessary: (1) That the
conceptions be pure and not empirical; (2) That they belong not to
intuition and sensibility, but to thought and understanding; (3) That
they be elementary conceptions, and as such, quite different from
deduced or compound conceptions; (4) That our table of these elementary
conceptions be complete, and fill up the whole sphere of the pure
understanding. Now this completeness of a science cannot be accepted
with confidence on the guarantee of a mere estimate of its existence in
an aggregate formed only by means of repeated experiments and attempts.
The completeness which we require is possible only by means of an idea
of the totality of the a priori cognition of the understanding, and
through the thereby determined division of the conceptions which form
the said whole; consequently, only by means of their connection in a
system. Pure understanding distinguishes itself not merely from
everything empirical, but also completely from all sensibility. It is a
unity self-subsistent, self-sufficient, and not to be enlarged by any
additions from without. Hence the sum of its cognition constitutes a
system to be determined by and comprised under an idea; and the
completeness and articulation of this system can at the same time serve
as a test of the correctness and genuineness of all the parts of
cognition that belong to it. The whole of this part of transcendental
logic consists of two books, of which the one contains the conceptions,
and the other the principles of pure understanding.


SS 2. Analytic of Conceptions.

By the term Analytic of Conceptions, I do not understand the
analysis of these, or the usual process in philosophical
investigations of dissecting the conceptions which present themselves,
according to their content, and so making them clear; but I mean the
hitherto little attempted dissection of the faculty of understanding
itself, in order to investigate the possibility of conceptions a
priori, by looking for them in the understanding alone, as their
birthplace, and analysing the pure use of this faculty. For this is
the proper duty of a transcendental philosophy; what remains is the
logical treatment of the conceptions in philosophy in general. We
shall therefore follow up the pure conceptions even to their germs
and beginnings in the human understanding, in which they lie, until
they are developed on occasions presented by experience, and, freed
by the same understanding from the empirical conditions attaching to
them, are set forth in their unalloyed purity.

CHAPTER I. Of the Transcendental Clue to the Discovery of all Pure
Conceptions of the Understanding.

SS 3. Introductory.

When we call into play a faculty of cognition, different conceptions
manifest themselves according to the different circumstances, and make
known this faculty, and assemble themselves into a more or less
extensive collection, according to the time or penetration that has
been applied to the consideration of them. Where this process,
conducted as it is mechanically, so to speak, will end, cannot be
determined with certainty. Besides, the conceptions which we
discover in this haphazard manner present themselves by no means in
order and systematic unity, but are at last coupled together only
according to resemblances to each other, and arranged in series,
according to the quantity of their content, from the simpler to the
more complex--series which are anything but systematic, though not
altogether without a certain kind of method in their construction.

Transcendental philosophy has the advantage, and moreover the
duty, of searching for its conceptions according to a principle;
because these conceptions spring pure and unmixed out of the
understanding as an absolute unity, and therefore must be connected
with each other according to one conception or idea. A connection of
this kind, however, furnishes us with a ready prepared rule, by
which its proper place may be assigned to every pure conception of
the understanding, and the completeness of the system of all be determined
a priori--both which would otherwise have been dependent on mere
choice or chance.

SS 4. SECTION 1. Of defined above Use of understanding in General.

The understanding was defined above only negatively, as a
non-sensuous faculty of cognition. Now, independently of
sensibility, we cannot possibly have any intuition; consequently,
the understanding is no faculty of intuition. But besides intuition
there is no other mode of cognition, except through conceptions;
consequently, the cognition of every, at least of every human,
understanding is a cognition through conceptions--not intuitive, but
discursive. All intuitions, as sensuous, depend on affections;
conceptions, therefore, upon functions. By the word function I
understand the unity of the act of arranging diverse representations
under one common representation. Conceptions, then, are based on the
spontaneity of thought, as sensuous intuitions are on the
receptivity of impressions. Now, the understanding cannot make any
other use of these conceptions than to judge by means of them. As no
representation, except an intuition, relates immediately to its
object, a conception never relates immediately to an object, but
only to some other representation thereof, be that an intuition or
itself a conception. A judgement, therefore, is the mediate
cognition of an object, consequently the representation of a
representation of it. In every judgement there is a conception which
applies to, and is valid for many other conceptions, and which among
these comprehends also a given representation, this last being
immediately connected with an object. For example, in the judgement--
"All bodies are divisible," our conception of divisible applies to
various other conceptions; among these, however, it is here
particularly applied to the conception of body, and this conception
of body relates to certain phenomena which occur to us. These objects,
therefore, are mediately represented by the conception of
divisibility. All judgements, accordingly, are functions of unity in
our representations, inasmuch as, instead of an immediate, a higher
representation, which comprises this and various others, is used for
our cognition of the object, and thereby many possible cognitions
are collected into one. But we can reduce all acts of the
understanding to judgements, so that understanding may be
represented as the faculty of judging. For it is, according to what
has been said above, a faculty of thought. Now thought is cognition
by means of conceptions. But conceptions, as predicates of possible
judgements, relate to some representation of a yet undetermined
object. Thus the conception of body indicates something--for
example, metal--which can be cognized by means of that conception.
It is therefore a conception, for the reason alone that other
representations are contained under it, by means of which it can
relate to objects. It is therefore the predicate to a possible
judgement; for example: "Every metal is a body." All the functions
of the understanding therefore can be discovered, when we can
completely exhibit the functions of unity in judgements. And that this
may be effected very easily, the following section will show.

SS 5. SECTION II. Of the Logical Function of the Understanding in

If we abstract all the content of a judgement, and consider only the
intellectual form thereof, we find that the function of thought in
a judgement can be brought under four heads, of which each contains
three momenta. These may be conveniently represented in the
following table:

Quantity of judgements

2 3
Quality Relation
Affirmative Categorical
Negative Hypothetical
Infinite Disjunctive


As this division appears to differ in some, though not essential
points, from the usual technique of logicians, the following
observations, for the prevention of otherwise possible
misunderstanding, will not be without their use.

1. Logicians say, with justice, that in the use of judgements in
syllogisms, singular judgements may be treated like universal ones.
For, precisely because a singular judgement has no extent at all,
its predicate cannot refer to a part of that which is contained in
the conception of the subject and be excluded from the rest. The predicate
is valid for the whole conception just as if it were a general
conception, and had extent, to the whole of which the predicate
applied. On the other hand, let us compare a singular with a general
judgement, merely as a cognition, in regard to quantity. The
singular judgement relates to the general one, as unity to infinity,
and is therefore in itself essentially different. Thus, if we estimate
a singular judgement (judicium singulare) not merely according to
its intrinsic validity as a judgement, but also as a cognition
generally, according to its quantity in comparison with that of
other cognitions, it is then entirely different from a general
judgement (judicium commune), and in a complete table of the momenta
of thought deserves a separate place--though, indeed, this would not
be necessary in a logic limited merely to the consideration of the
use of judgements in reference to each other.

2. In like manner, in transcendental logic, infinite must be
distinguished from affirmative judgements, although in general logic
they are rightly enough classed under affirmative. General logic
abstracts all content of the predicate (though it be negative), and
only considers whether the said predicate be affirmed or denied of
the subject. But transcendental logic considers also the worth or
content of this logical affirmation--an affirmation by means of a
merely negative predicate, and inquires how much the sum total of
our cognition gains by this affirmation. For example, if I say of
the soul, "It is not mortal"--by this negative judgement I should at
least ward off error. Now, by the proposition, "The soul is not
mortal," I have, in respect of the logical form, really affirmed,
inasmuch as I thereby place the soul in the unlimited sphere of
immortal beings. Now, because of the whole sphere of possible
existences, the mortal occupies one part, and the immortal the
other, neither more nor less is affirmed by the proposition than
that the soul is one among the infinite multitude of things which
remain over, when I take away the whole mortal part. But by this
proceeding we accomplish only this much, that the infinite sphere of
all possible existences is in so far limited that the mortal is
excluded from it, and the soul is placed in the remaining part of
the extent of this sphere. But this part remains, notwithstanding this
exception, infinite, and more and more parts may be taken away from
the whole sphere, without in the slightest degree thereby augmenting
or affirmatively determining our conception of the soul. These
judgements, therefore, infinite in respect of their logical extent,
are, in respect of the content of their cognition, merely
limitative; and are consequently entitled to a place in our
transcendental table of all the momenta of thought in judgements,
because the function of the understanding exercised by them may
perhaps be of importance in the field of its pure a priori cognition.

3. All relations of thought in judgements are those (a) of the
predicate to the subject; (b) of the principle to its consequence;
(c) of the divided cognition and all the members of the division to
each other. In the first of these three classes, we consider only two
conceptions; in the second, two judgements; in the third, several
judgements in relation to each other. The hypothetical proposition,
"If perfect justice exists, the obstinately wicked are punished,"
contains properly the relation to each other of two propositions,
namely, "Perfect justice exists," and "The obstinately wicked are
punished." Whether these propositions are in themselves true is a
question not here decided. Nothing is cogitated by means of this
judgement except a certain consequence. Finally, the disjunctive
judgement contains a relation of two or more propositions to each
other--a relation not of consequence, but of logical opposition, in
so far as the sphere of the one proposition excludes that of the other.
But it contains at the same time a relation of community, in so far
as all the propositions taken together fill up the sphere of the
cognition. The disjunctive judgement contains, therefore, the relation
of the parts of the whole sphere of a cognition, since the sphere of
each part is a complemental part of the sphere of the other, each
contributing to form the sum total of the divided cognition. Take,
for example, the proposition, "The world exists either through blind
chance, or through internal necessity, or through an external
cause." Each of these propositions embraces a part of the sphere of
our possible cognition as to the existence of a world; all of them
taken together, the whole sphere. To take the cognition out of one
of these spheres, is equivalent to placing it in one of the others;
and, on the other hand, to place it in one sphere is equivalent to
taking it out of the rest. There is, therefore, in a disjunctive
judgement a certain community of cognitions, which consists in this,
that they mutually exclude each other, yet thereby determine, as a
whole, the true cognition, inasmuch as, taken together, they make up
the complete content of a particular given cognition. And this is
all that I find necessary, for the sake of what follows, to remark
in this place.

4. The modality of judgements is a quite peculiar function, with
this distinguishing characteristic, that it contributes nothing to
the content of a judgement (for besides quantity, quality, and relation,
there is nothing more that constitutes the content of a judgement),
but concerns itself only with the value of the copula in relation to
thought in general. Problematical judgements are those in which the
affirmation or negation is accepted as merely possible (ad libitum).
In the assertorical, we regard the proposition as real (true); in
the apodeictical, we look on it as necessary.* Thus the two judgements
(antecedens et consequens), the relation of which constitutes a
hypothetical judgement, likewise those (the members of the division)
in whose reciprocity the disjunctive consists, are only problematical.
In the example above given the proposition, "There exists perfect
justice," is not stated assertorically, but as an ad libitum
judgement, which someone may choose to adopt, and the consequence
alone is assertorical. Hence such judgements may be obviously false,
and yet, taken problematically, be conditions of our cognition of
the truth. Thus the proposition, "The world exists only by blind
chance," is in the disjunctive judgement of problematical import only:
that is to say, one may accept it for the moment, and it helps us
(like the indication of the wrong road among all the roads that one
can take) to find out the true proposition. The problematical
proposition is, therefore, that which expresses only logical
possibility (which is not objective); that is, it expresses a free
choice to admit the validity of such a proposition--a merely arbitrary
reception of it into the understanding. The assertorical speaks of
logical reality or truth; as, for example, in a hypothetical
syllogism, the antecedens presents itself in a problematical form in
the major, in an assertorical form in the minor, and it shows that
the proposition is in harmony with the laws of the understanding. The
apodeictical proposition cogitates the assertorical as determined by
these very laws of the understanding, consequently as affirming a
priori, and in this manner it expresses logical necessity. Now because
all is here gradually incorporated with the understanding--inasmuch
as in the first place we judge problematically; then accept
assertorically our judgement as true; lastly, affirm it as inseparably
united with the understanding, that is, as necessary and apodeictical--
we may safely reckon these three functions of modality as so many
momenta of thought.

[*Footnote: Just as if thought were in the first instance a function
of the understanding; in the second, of judgement; in the third, of
reason. A remark which will be explained in the sequel.]

SS 6. SECTION III. Of the Pure Conceptions of the Understanding, or

General logic, as has been repeatedly said, makes abstraction of all
content of cognition, and expects to receive representations from some
other quarter, in order, by means of analysis, to convert them into
conceptions. On the contrary, transcendental logic has lying before
it the manifold content of a priori sensibility, which transcendental
aesthetic presents to it in order to give matter to the pure
conceptions of the understanding, without which transcendental logic
would have no content, and be therefore utterly void. Now space and
time contain an infinite diversity of determinations of pure a
priori intuition, but are nevertheless the condition of the mind's
receptivity, under which alone it can obtain representations of
objects, and which, consequently, must always affect the conception
of these objects. But the spontaneity of thought requires that this
diversity be examined after a certain manner, received into the
mind, and connected, in order afterwards to form a cognition out of
it. This Process I call synthesis.

By the word synthesis, in its most general signification, I
understand the process of joining different representations to each
other and of comprehending their diversity in one cognition. This
synthesis is pure when the diversity is not given empirically but a
priori (as that in space and time). Our representations must be
given previously to any analysis of them; and no conceptions can
arise, quoad their content, analytically. But the synthesis of a
diversity (be it given a priori or empirically) is the first requisite
for the production of a cognition, which in its beginning, indeed,
may be crude and confused, and therefore in need of analysis--still,
synthesis is that by which alone the elements of our cognitions are
collected and united into a certain content, consequently it is the
first thing on which we must fix our attention, if we wish to
investigate the origin of our knowledge.

Synthesis, generally speaking, is, as we shall afterwards see, the
mere operation of the imagination--a blind but indispensable
function of the soul, without which we should have no cognition
whatever, but of the working of which we are seldom even conscious.
But to reduce this synthesis to conceptions is a function of the
understanding, by means of which we attain to cognition, in the proper
meaning of the term.

Pure synthesis, represented generally, gives us the pure
conception of the understanding. But by this pure synthesis, I mean
that which rests upon a basis of a priori synthetical unity. Thus,
our numeration (and this is more observable in large numbers) is a
synthesis according to conceptions, because it takes place according
to a common basis of unity (for example, the decade). By means of this
conception, therefore, the unity in the synthesis of the manifold
becomes necessary.

By means of analysis different representations are brought under one
conception--an operation of which general logic treats. On the other
hand, the duty of transcendental logic is to reduce to conceptions,
not representations, but the pure synthesis of representations. The
first thing which must be given to us for the sake of the a priori
cognition of all objects, is the diversity of the pure intuition;
the synthesis of this diversity by means of the imagination is the
second; but this gives, as yet, no cognition. The conceptions which
give unity to this pure synthesis, and which consist solely in the
representation of this necessary synthetical unity, furnish the
third requisite for the cognition of an object, and these
conceptions are given by the understanding.

The same function which gives unity to the different
representation in a judgement, gives also unity to the mere
synthesis of different representations in an intuition; and this unity
we call the pure conception of the understanding. Thus, the same
understanding, and by the same operations, whereby in conceptions,
by means of analytical unity, it produced the logical form of a
judgement, introduces, by means of the synthetical unity of the
manifold in intuition, a transcendental content into its
representations, on which account they are called pure conceptions
of the understanding, and they apply a priori to objects, a result
not within the power of general logic.

In this manner, there arise exactly so many pure conceptions of
the understanding, applying a priori to objects of intuition in
general, as there are logical functions in all possible judgements.
For there is no other function or faculty existing in the
understanding besides those enumerated in that table. These
conceptions we shall, with Aristotle, call categories, our purpose
being originally identical with his, notwithstanding the great
difference in the execution.


1 2

Of Quantity Of Quality
Unity Reality
Plurality Negation
Totality Limitation

Of Relation
Of Inherence and Subsistence (substantia et accidens)
Of Causality and Dependence (cause and effect)
Of Community (reciprocity between the agent and patient)

Of Modality

This, then, is a catalogue of all the originally pure conceptions of
the synthesis which the understanding contains a priori, and these
conceptions alone entitle it to be called a pure understanding;
inasmuch as only by them it can render the manifold of intuition
conceivable, in other words, think an object of intuition. This
division is made systematically from a common principle, namely the
faculty of judgement (which is just the same as the power of thought),
and has not arisen rhapsodically from a search at haphazard after pure
conceptions, respecting the full number of which we never could be
certain, inasmuch as we employ induction alone in our search,
without considering that in this way we can never understand wherefore
precisely these conceptions, and none others, abide in the pure
understanding. It was a design worthy of an acute thinker like
Aristotle, to search for these fundamental conceptions. Destitute,
however, of any guiding principle, he picked them up just as they
occurred to him, and at first hunted out ten, which he called
categories (predicaments). Afterwards be believed that he had
discovered five others, which were added under the name of post
predicaments. But his catalogue still remained defective. Besides,
there are to be found among them some of the modes of pure sensibility
(quando, ubi, situs, also prius, simul), and likewise an empirical
conception (motus)--which can by no means belong to this
genealogical register of the pure understanding. Moreover, there are
deduced conceptions (actio, passio) enumerated among the original
conceptions, and, of the latter, some are entirely wanting.

With regard to these, it is to be remarked, that the categories,
as the true primitive conceptions of the pure understanding, have also
their pure deduced conceptions, which, in a complete system of
transcendental philosophy, must by no means be passed over; though
in a merely critical essay we must be contented with the simple
mention of the fact.

Let it be allowed me to call these pure, but deduced conceptions
of the understanding, the predicables of the pure understanding, in
contradistinction to predicaments. If we are in possession of the
original and primitive, the deduced and subsidiary conceptions can
easily be added, and the genealogical tree of the understanding
completely delineated. As my present aim is not to set forth a
complete system, but merely the principles of one, I reserve this task
for another time. It may be easily executed by any one who will
refer to the ontological manuals, and subordinate to the category of
causality, for example, the predicables of force, action, passion;
to that of community, those of presence and resistance; to the
categories of modality, those of origination, extinction, change;
and so with the rest. The categories combined with the modes of pure
sensibility, or with one another, afford a great number of deduced
a priori conceptions; a complete enumeration of which would be a
useful and not unpleasant, but in this place a perfectly
dispensable, occupation.

I purposely omit the definitions of the categories in this treatise.
I shall analyse these conceptions only so far as is necessary for
the doctrine of method, which is to form a part of this critique. In
a system of pure reason, definitions of them would be with justice
demanded of me, but to give them here would only bide from our view
the main aim of our investigation, at the same time raising doubts
and objections, the consideration of which, without injustice to our
main purpose, may be very well postponed till another opportunity.
Meanwhile, it ought to be sufficiently clear, from the little we
have already said on this subject, that the formation of a complete
vocabulary of pure conceptions, accompanied by all the requisite
explanations, is not only a possible, but an easy undertaking. The
compartments already exist; it is only necessary to fill them up;
and a systematic topic like the present, indicates with perfect
precision the proper place to which each conception belongs, while
it readily points out any that have not yet been filled up.

SS 7.

Our table of the categories suggests considerations of some
importance, which may perhaps have significant results in regard to
the scientific form of all rational cognitions. For, that this table
is useful in the theoretical part of philosophy, nay, indispensable
for the sketching of the complete plan of a science, so far as that
science rests upon conceptions a priori, and for dividing it
mathematically, according to fixed principles, is most manifest from
the fact that it contains all the elementary conceptions of the
understanding, nay, even the form of a system of these in the
understanding itself, and consequently indicates all the momenta,
and also the internal arrangement of a projected speculative
science, as I have elsewhere shown. [Footnote: In the
Metaphysical Principles of Natural Science.] Here follow some of these

I. This table, which contains four classes of conceptions of the
understanding, may, in the first instance, be divided into two
classes, the first of which relates to objects of intuition--pure as
well as empirical; the second, to the existence of these objects,
either in relation to one another, or to the understanding.

The former of these classes of categories I would entitle the
mathematical, and the latter the dynamical categories. The former,
as we see, has no correlates; these are only to be found in the second
class. This difference must have a ground in the nature of the human

II. The number of the categories in each class is always the same,
namely, three--a fact which also demands some consideration, because
in all other cases division a priori through conceptions is
necessarily dichotomy. It is to be added, that the third category in
each triad always arises from the combination of the second with the

Thus totality is nothing else but plurality contemplated as unity;
limitation is merely reality conjoined with negation; community is
the causality of a substance, reciprocally determining, and determined
by other substances; and finally, necessity is nothing but
existence, which is given through the possibility itself. Let it not
be supposed, however, that the third category is merely a deduced,
and not a primitive conception of the pure understanding. For the
conjunction of the first and second, in order to produce the third
conception, requires a particular function of the understanding, which
is by no means identical with those which are exercised in the first
and second. Thus, the conception of a number (which belongs to the
category of totality) is not always possible, where the conceptions
of multitude and unity exist (for example, in the representation of
the infinite). Or, if I conjoin the conception of a cause with that
of a substance, it does not follow that the conception of influence,
that is, how one substance can be the cause of something in another
substance, will be understood from that. Thus it is evident that a
particular act of the understanding is here necessary; and so in the
other instances.

III. With respect to one category, namely, that of community,
which is found in the third class, it is not so easy as with the
others to detect its accordance with the form of the disjunctive
judgement which corresponds to it in the table of the logical

In order to assure ourselves of this accordance, we must observe
that in every disjunctive judgement, the sphere of the judgement (that
is, the complex of all that is contained in it) is represented as a
whole divided into parts; and, since one part cannot be contained in
the other, they are cogitated as co-ordinated with, not subordinated
to each other, so that they do not determine each other
unilaterally, as in a linear series, but reciprocally, as in an
aggregate--(if one member of the division is posited, all the rest
are excluded; and conversely).

Now a like connection is cogitated in a whole of things; for one
thing is not subordinated, as effect, to another as cause of its
existence, but, on the contrary, is co-ordinated contemporaneously
and reciprocally, as a cause in relation to the determination of the
others (for example, in a body--the parts of which mutually attract
and repel each other). And this is an entirely different kind of
connection from that which we find in the mere relation of the cause
to the effect (the principle to the consequence), for in such a
connection the consequence does not in its turn determine the
principle, and therefore does not constitute, with the latter, a
whole--just as the Creator does not with the world make up a whole.
The process of understanding by which it represents to itself the
sphere of a divided conception, is employed also when we think of a
thing as divisible; and in the same manner as the members of the
division in the former exclude one another, and yet are connected in
one sphere, so the understanding represents to itself the parts of
the latter, as having--each of them--an existence (as substances),
independently of the others, and yet as united in one whole.

SS 8.

In the transcendental philosophy of the ancients there exists one more
leading division, which contains pure conceptions of the understanding,
and which, although not numbered among the categories, ought, according
to them, as conceptions a priori, to be valid of objects. But in this
case they would augment the number of the categories; which cannot be.
These are set forth in the proposition, so renowned among the
schoolmen--"Quodlibet ens est UNUM, VERUM, BONUM." Now, though the
inferences from this principle were mere tautological propositions, and
though it is allowed only by courtesy to retain a place in modern
metaphysics, yet a thought which maintained itself for such a length of
time, however empty it seems to be, deserves an investigation of its
origin, and justifies the conjecture that it must be grounded in some
law of the understanding, which, as is often the case, has only been
erroneously interpreted. These pretended transcendental predicates are,
in fact, nothing but logical requisites and criteria of all cognition
of objects, and they employ, as the basis for this cognition, the
categories of quantity, namely, unity, plurality, and totality. But
these, which must be taken as material conditions, that is, as
belonging to the possibility of things themselves, they employed merely
in a formal signification, as belonging to the logical requisites of
all cognition, and yet most unguardedly changed these criteria of
thought into properties of objects, as things in themselves. Now, in
every cognition of an object, there is unity of conception, which may
be called qualitative unity, so far as by this term we understand only
the unity in our connection of the manifold; for example, unity of the
theme in a play, an oration, or a story. Secondly, there is truth in
respect of the deductions from it. The more true deductions we have
from a given conception, the more criteria of its objective reality.
This we might call the qualitative plurality of characteristic marks,
which belong to a conception as to a common foundation, but are not
cogitated as a quantity in it. Thirdly, there is perfection--which
consists in this, that the plurality falls back upon the unity of the
conception, and accords completely with that conception and with no
other. This we may denominate qualitative completeness. Hence it is
evident that these logical criteria of the possibility of cognition are
merely the three categories of quantity modified and transformed to
suit an unauthorized manner of applying them. That is to say, the three
categories, in which the unity in the production of the quantum must be
homogeneous throughout, are transformed solely with a view to the
connection of heterogeneous parts of cognition in one act of
consciousness, by means of the quality of the cognition, which is the
principle of that connection. Thus the criterion of the possibility of
a conception (not of its object) is the definition of it, in which the
unity of the conception, the truth of all that may be immediately
deduced from it, and finally, the completeness of what has been thus
deduced, constitute the requisites for the reproduction of the whole
conception. Thus also, the criterion or test of an hypothesis is the
intelligibility of the received principle of explanation, or its unity
(without help from any subsidiary hypothesis)--the truth of our
deductions from it (consistency with each other and with
experience)--and lastly, the completeness of the principle of the
explanation of these deductions, which refer to neither more nor less
than what was admitted in the hypothesis, restoring analytically and a
posteriori, what was cogitated synthetically and a priori. By the
conceptions, therefore, of unity, truth, and perfection, we have made
no addition to the transcendental table of the categories, which is
complete without them. We have, on the contrary, merely employed the
three categories of quantity, setting aside their application to
objects of experience, as general logical laws of the consistency of
cognition with itself.

CHAPTER II Of the Deduction of the Pure Conceptions of the Understanding.

SS 9. SECTION I Of the Principles of a Transcendental Deduction
in general.

Teachers of jurisprudence, when speaking of rights and claims,
distinguish in a cause the question of right (quid juris) from the
question of fact (quid facti), and while they demand proof of both,
they give to the proof of the former, which goes to establish right
or claim in law, the name of deduction. Now we make use of a great
number of empirical conceptions, without opposition from any one; and
consider ourselves, even without any attempt at deduction, justified
in attaching to them a sense, and a supposititious signification,
because we have always experience at hand to demonstrate their
objective reality. There exist also, however, usurped conceptions,
such as fortune, fate, which circulate with almost universal
indulgence, and yet are occasionally challenged by the question, "quid
juris?" In such cases, we have great difficulty in discovering any
deduction for these terms, inasmuch as we cannot produce any
manifest ground of right, either from experience or from reason, on
which the claim to employ them can be founded.

Among the many conceptions, which make up the very variegated web of
human cognition, some are destined for pure use a priori,
independent of all experience; and their title to be so employed
always requires a deduction, inasmuch as, to justify such use of them,
proofs from experience are not sufficient; but it is necessary to know
how these conceptions can apply to objects without being derived
from experience. I term, therefore, an examination of the manner in
which conceptions can apply a priori to objects, the transcendental
deduction of conceptions, and I distinguish it from the empirical
deduction, which indicates the mode in which conception is obtained
through experience and reflection thereon; consequently, does not
concern itself with the right, but only with the fact of our obtaining
conceptions in such and such a manner. We have already seen that we
are in possession of two perfectly different kinds of conceptions,
which nevertheless agree with each other in this, that they both apply
to objects completely a priori. These are the conceptions of space
and time as forms of sensibility, and the categories as pure conceptions
of the understanding. To attempt an empirical deduction of either of
these classes would be labour in vain, because the distinguishing
characteristic of their nature consists in this, that they apply to
their objects, without having borrowed anything from experience
towards the representation of them. Consequently, if a deduction of
these conceptions is necessary, it must always be transcendental.

Meanwhile, with respect to these conceptions, as with respect to all
our cognition, we certainly may discover in experience, if not the
principle of their possibility, yet the occasioning causes of their
production. It will be found that the impressions of sense give the
first occasion for bringing into action the whole faculty of
cognition, and for the production of experience, which contains two
very dissimilar elements, namely, a matter for cognition, given by
the senses, and a certain form for the arrangement of this matter,
arising out of the inner fountain of pure intuition and thought; and
these, on occasion given by sensuous impressions, are called into exercise
and produce conceptions. Such an investigation into the first efforts
of our faculty of cognition to mount from particular perceptions to
general conceptions is undoubtedly of great utility; and we have to
thank the celebrated Locke for having first opened the way for this
inquiry. But a deduction of the pure a priori conceptions of course
never can be made in this way, seeing that, in regard to their
future employment, which must be entirely independent of experience,
they must have a far different certificate of birth to show from
that of a descent from experience. This attempted physiological
derivation, which cannot properly be called deduction, because it
relates merely to a quaestio facti, I shall entitle an explanation
of the possession of a pure cognition. It is therefore manifest that
there can only be a transcendental deduction of these conceptions
and by no means an empirical one; also, that all attempts at an
empirical deduction, in regard to pure a priori conceptions, are vain,
and can only be made by one who does not understand the altogether
peculiar nature of these cognitions.

But although it is admitted that the only possible deduction of pure
a priori cognition is a transcendental deduction, it is not, for
that reason, perfectly manifest that such a deduction is absolutely
necessary. We have already traced to their sources the conceptions
of space and time, by means of a transcendental deduction, and we have
explained and determined their objective validity a priori.
Geometry, nevertheless, advances steadily and securely in the province
of pure a priori cognitions, without needing to ask from philosophy
any certificate as to the pure and legitimate origin of its
fundamental conception of space. But the use of the conception in this
science extends only to the external world of sense, the pure form
of the intuition of which is space; and in this world, therefore,
all geometrical cognition, because it is founded upon a priori
intuition, possesses immediate evidence, and the objects of this
cognition are given a priori (as regards their form) in intuition by
and through the cognition itself. With the pure conceptions of
understanding, on the contrary, commences the absolute necessity of
seeking a transcendental deduction, not only of these conceptions
themselves, but likewise of space, because, inasmuch as they make
affirmations concerning objects not by means of the predicates of
intuition and sensibility, but of pure thought a priori, they apply
to objects without any of the conditions of sensibility. Besides, not
being founded on experience, they are not presented with any object
in a priori intuition upon which, antecedently to experience, they
might base their synthesis. Hence results, not only doubt as to the
objective validity and proper limits of their use, but that even our
conception of space is rendered equivocal; inasmuch as we are very
ready with the aid of the categories, to carry the use of this
conception beyond the conditions of sensuous intuition--and, for
this reason, we have already found a transcendental deduction of it
needful. The reader, then, must be quite convinced of the absolute
necessity of a transcendental deduction, before taking a single step
in the field of pure reason; because otherwise he goes to work
blindly, and after he has wondered about in all directions, returns
to the state of utter ignorance from which he started. He ought,
moreover, clearly to recognize beforehand the unavoidable difficulties
in his undertaking, so that he may not afterwards complain of the
obscurity in which the subject itself is deeply involved, or become
too soon impatient of the obstacles in his path; because we have a
choice of only two things--either at once to give up all pretensions
to knowledge beyond the limits of possible experience, or to bring
this critical investigation to completion.

We have been able, with very little trouble, to make it
comprehensible how the conceptions of space and time, although a
priori cognitions, must necessarily apply to external objects, and
render a synthetical cognition of these possible, independently of
all experience. For inasmuch as only by means of such pure form of
sensibility an object can appear to us, that is, be an object of
empirical intuition, space and time are pure intuitions, which contain
a priori the condition of the possibility of objects as phenomena,
and an a priori synthesis in these intuitions possesses objective

On the other hand, the categories of the understanding do not
represent the conditions under which objects are given to us in
intuition; objects can consequently appear to us without necessarily
connecting themselves with these, and consequently without any
necessity binding on the understanding to contain a priori the
conditions of these objects. Thus we find ourselves involved in a
difficulty which did not present itself in the sphere of
sensibility, that is to say, we cannot discover how the subjective
conditions of thought can have objective validity, in other words,
can become conditions of the possibility of all cognition of objects;
for phenomena may certainly be given to us in intuition without any
help from the functions of the understanding. Let us take, for
example, the conception of cause, which indicates a peculiar kind of
synthesis, namely, that with something, A, something entirely
different, B, is connected according to a law. It is not a priori
manifest why phenomena should contain anything of this kind (we are
of course debarred from appealing for proof to experience, for the
objective validity of this conception must be demonstrated a
priori), and it hence remains doubtful a priori, whether such a
conception be not quite void and without any corresponding object
among phenomena. For that objects of sensuous intuition must
correspond to the formal conditions of sensibility existing a priori
in the mind is quite evident, from the fact that without these they
could not be objects for us; but that they must also correspond to
the conditions which understanding requires for the synthetical unity
of thought is an assertion, the grounds for which are not so easily
to be discovered. For phenomena might be so constituted as not to
correspond to the conditions of the unity of thought; and all things
might lie in such confusion that, for example, nothing could be met
with in the sphere of phenomena to suggest a law of synthesis, and
so correspond to the conception of cause and effect; so that this
conception would be quite void, null, and without significance. Phenomena
would nevertheless continue to present objects to our intuition; for
mere intuition does not in any respect stand in need of the functions
of thought.

If we thought to free ourselves from the labour of these
investigations by saying: "Experience is constantly offering us
examples of the relation of cause and effect in phenomena, and
presents us with abundant opportunity of abstracting the conception
of cause, and so at the same time of corroborating the objective validity
of this conception"; we should in this case be overlooking the fact,
that the conception of cause cannot arise in this way at all; that,
on the contrary, it must either have an a priori basis in the,
understanding, or be rejected as a mere chimera. For this conception
demands that something, A, should be of such a nature that something
else, B, should follow from it necessarily, and according to an
absolutely universal law. We may certainly collect from phenomena a
law, according to which this or that usually happens, but the
element of necessity is not to be found in it. Hence it is evident
that to the synthesis of cause and effect belongs a dignity, which
is utterly wanting in any empirical synthesis; for it is no mere
mechanical synthesis, by means of addition, but a dynamical one;
that is to say, the effect is not to be cogitated as merely annexed
to the cause, but as posited by and through the cause, and resulting
from it. The strict universality of this law never can be a
characteristic of empirical laws, which obtain through induction
only a comparative universality, that is, an extended range of
practical application. But the pure conceptions of the understanding
would entirely lose all their peculiar character, if we treated them
merely as the productions of experience.

SS 10. Transition to the Transcendental Deduction of the

There are only two possible ways in which synthetical representation
and its objects can coincide with and relate necessarily to each
other, and, as it were, meet together. Either the object alone makes
the representation possible, or the representation alone makes the
object possible. In the former case, the relation between them is only
empirical, and an a priori representation is impossible. And this is
the case with phenomena, as regards that in them which is referable
to mere sensation. In the latter case--although representation alone
(for of its causality, by means of the will, we do not here speak)
does not produce the object as to its existence, it must nevertheless
be a priori determinative in regard to the object, if it is only by
means of the representation that we can cognize anything as an object.
Now there are only two conditions of the possibility of a cognition
of objects; firstly, intuition, by means of which the object, though
only as phenomenon, is given; secondly, conception, by means of which
the object which corresponds to this intuition is thought. But it is
evident from what has been said on aesthetic that the first condition,
under which alone objects can be intuited, must in fact exist, as a
formal basis for them, a priori in the mind. With this formal
condition of sensibility, therefore, all phenomena necessarily
correspond, because it is only through it that they can be phenomena
at all; that is, can be empirically intuited and given. Now the
question is whether there do not exist, a priori in the mind,
conceptions of understanding also, as conditions under which alone
something, if not intuited, is yet thought as object. If this question
be answered in the affirmative, it follows that all empirical
cognition of objects is necessarily conformable to such conceptions,
since, if they are not presupposed, it is impossible that anything
can be an object of experience. Now all experience contains, besides
the intuition of the senses through which an object is given, a conception
also of an object that is given in intuition. Accordingly, conceptions
of objects in general must lie as a priori conditions at the
foundation of all empirical cognition; and consequently, the objective
validity of the categories, as a priori conceptions, will rest upon
this, that experience (as far as regards the form of thought) is
possible only by their means. For in that case they apply
necessarily and a priori to objects of experience, because only
through them can an object of experience be thought.

The whole aim of the transcendental deduction of all a priori
conceptions is to show that these conceptions are a priori
conditions of the possibility of all experience. Conceptions which
afford us the objective foundation of the possibility of experience
are for that very reason necessary. But the analysis of the
experiences in which they are met with is not deduction, but only an
illustration of them, because from experience they could never
derive the attribute of necessity. Without their original
applicability and relation to all possible experience, in which all
objects of cognition present themselves, the relation of the
categories to objects, of whatever nature, would be quite

The celebrated Locke, for want of due reflection on these points,
and because he met with pure conceptions of the understanding in
experience, sought also to deduce them from experience, and yet
proceeded so inconsequently as to attempt, with their aid, to arrive
it cognitions which lie far beyond the limits of all experience. David
Hume perceived that, to render this possible, it was necessary that
the conceptions should have an a priori origin. But as he could not
explain how it was possible that conceptions which are not connected
with each other in the understanding must nevertheless be thought as
necessarily connected in the object--and it never occurred to him that
the understanding itself might, perhaps, by means of these
conceptions, be the author of the experience in which its objects were
presented to it--he was forced to drive these conceptions from
experience, that is, from a subjective necessity arising from repeated
association of experiences erroneously considered to be objective--
in one word, from habit. But he proceeded with perfect consequence
and declared it to be impossible, with such conceptions and the principles
arising from them, to overstep the limits of experience. The empirical
derivation, however, which both of these philosophers attributed to
these conceptions, cannot possibly be reconciled with the fact that
we do possess scientific a priori cognitions, namely, those of pure
mathematics and general physics.

The former of these two celebrated men opened a wide door to
extravagance--(for if reason has once undoubted right on its side,
it will not allow itself to be confined to set limits, by vague
recommendations of moderation); the latter gave himself up entirely
to scepticism--a natural consequence, after having discovered, as he
thought, that the faculty of cognition was not trustworthy. We now
intend to make a trial whether it be not possible safely to conduct
reason between these two rocks, to assign her determinate limits,
and yet leave open for her the entire sphere of her legitimate

I shall merely premise an explanation of what the categories are.
They are conceptions of an object in general, by means of which its
intuition is contemplated as determined in relation to one of the
logical functions of judgement. The following will make this plain.
The function of the categorical judgement is that of the relation of
subject to predicate; for example, in the proposition: "All bodies
are divisible." But in regard to the merely logical use of the
understanding, it still remains undetermined to which Of these two
conceptions belongs the function Of subject and to which that of
predicate. For we could also say: "Some divisible is a body." But
the category of substance, when the conception of a body is brought
under it, determines that; and its empirical intuition in experience

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