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Kant

The Critique of Pure Reason 

 Transcendental Aesthetic: B

return to 'critique of pure reason' contents page 

Immanuel Kant (1724-1804)

auxiliary sources for 'The Critique'

VG: Professor Victor Gijsbers, Netherlands, youtube lectures

DR: Professor Daniel Robinson, Oxford, youtube lectures

RPW: Prof. Robert Paul Wolff, youtube lectures

MJ: translation, Mieklejohn

PG: translation, Paul Guyer

MM: translation, Max Muller: "[His] main merit, as he has very justly claimed, is his greater accuracy in rendering passages in which a specially exact appreciation of the niceties of German idiom happens to be important for the sense." TN

TN: translation, N.K. Smith

PR: translation-commentary, P.M. Rudisill

CN: commentary, N.K. Smith

SG: commentary, Sebastian Gardner

SP: glossary, Stephen Palmquist

LT: glossary, Lucas Thorpe

 *********************************************

VG: Kant will be investigating elements of human cognition. The first part of the book, which constitutes the vast majority of the book, is the Transcendental Doctrine Of Elements. The Transcendental Aesthetic is the first section of this major part.

Kant uses "aesthetic" in its original sense of having to do with sensibility, the senses. Then he'll move on to discuss understanding or reason in the Transcendental Logic, which is divided into two sections, the understanding proper (the Transcendental Analytic) and reason proper, reason in the narrow sense (the Transcendental Dialectic). These are the elements of human cognition, having to do with what we can know a priori.

The B version will be in focus as the A does not have anything more to add.

Kant begins by offering definitions which give us a conceptual space into which all the subsequent discussions are going to fit.

The first distinction Kant is going to make is between intuition and the understanding.

Intuition, at least for us humans, is going to be sensibility. So, really, what we’re talking about here is sensibility and the understanding or reason, in some suitably broad sense.

In whatever way, and through whatever means, a cognition may relate to objects, that through which it relates immediately to them, and at which all thought as a means is directed as an end, is intuition.

VG: Intuition in the German has this visual sense, it’s like seeing something.

What is an intuition? It is that by which an object is given to us. In an intuition, an object is immediately given to us.

So, suppose that this moment I’m thinking about cows, or unicorns, or trees – what am I doing? I am using concepts, and I can think about these things, pro and con, etc., but in none of this am I in contact with some specific object. Editor's note: I think the meaning here is, we're thinking about these things without actually looking at the object itself. And maybe this is why Kant chose the German "intuition" which means "seeing", that is, we're looking at the actual object not just conjuring it.

What Kant is saying here when he says "all thought as a means is directed” to intuitions is that, what we want in thought is to rise to a level of what Kant calls “cognition.”

“Cognition” is something that relates to an actual object. It’s not some free-floating thought or dream image - no, it actually relates to something real, some object.

My thoughts, per se – the mental images of the cow, unicorn, the tree – are not going to put me in touch with an actual object. What I need for that, Kant is telling us, is an intuition.

By Kant’s definition, an intuition is a representation, a mental event, in which an object is given to me. So, with an intuition I am immediately in contact with an object.

This, however,
takes place only insofar as the object is given to us; but this in turn, at
least for us humans, is possible only if it affects the mind in a certain
way. The capacity (receptivity) to acquire representations through the
way in which we are affected by objects is called sensibility.

VG: “for us humans”: as opposed, possibly, to angels and gods, who might be able to bring into existence objects simply by thinking about them; this, Kant will call, “intellectual intuition.” But we have sensible intuition.

VG: An object can be given to us, we can come into contact with some individual object, only if it affects the mind in a certain way, and this capacity to affect us is what Kant calls sensibility.

Any sensation that we experience does so because we have sensibility; the sensation represents an activation of the power or capacity for sensibility, in order to have intuitions.

Objects are
therefore given to us by means of sensibility, and it alone affords us in
tuitions; but they are thought through the understanding, and from it
arise concepts. But all thought, whether straightaway (direct) or
through a detour (indirect), must, by means of certain marks, ulti
mately be related to intuitions, thus, in our case, to sensibility, since
there is no other way in which objects can be given to us.

VG: Concepts are always general and never grasp the individuality of objects. Concepts are given by sensibility and intuitions but are then “thought through” by the understanding, and from this analysis arise concepts.

Being in touch with an individual object is very different from thinking about it using concepts. This distinction is crucial to Kant, to the way the The Critique is set up, because the Transcendental Aesthetic is going to be about intuition, and concepts will come into play when we get to the Transcendental Logic, which is about the understanding, the capacity for using concepts.

The effect of an object on the capacity for representation, insofar as
we are affected by it, is sensation.

VG: Sensibility is the capacity to be affected, when this affection happens we have a sensation. Sensation is being affected, sensibility is the capacity to be affected.

That intuition, which is related to the object through sensation, is called empirical.

VG: An intuition, like a mental state in which an object is given to us, and if this is through a sensation, then we call it an empirical intuition.

VG: Did Kant say that all intuition, for humans, is through sensation? which would mean that all intuition is empirical. But this is going to turn out to be not true. This is because of the distinction between sensation and sensibility. So, what Kant has told us is that all intuition, in humans, works through sensibility, but now, in a little while, Kant is going to put to work this distinction between sensibility – the capacity to be affected by objects – and sensation – the being affected by objects – because Kant is going to tell us that when we talk about sensation we can make a distinction between the form and the matter of sensation. And the form of sensation is sort of the underlying order, the underlying way all our sensation happens. It is sort of the formal aspect of our sensibility, and it’s something that is already there, in a sense, before it’s filled in with the matter of any sensation. So, to look forward a bit, what Kant is going to argue is that sensibility has a form, which is space and time. And when we have a sensation, what’s happening is that this form, space and time, is being filled in with the matter of sensation, which is given to us. When we talk about sensation, when we are in contact with an object through the matter of sensation, through the actual sensations, then we have an empirical intuition. But, Kant says, it’s also possible to be in contact with something – what could it be – it’s going to turn out to be space and time itself, through merely the form of sensibility. So, without any actual sensation, this is going to be a non-empirical intuition, which Kant calls a pure intuition.

The undetermined object of an empirical intuition is called appearance.

VG: This is a very, very, very important statement by Kant. His term “appearance” is going to keep on coming up again and again, and it’s very easy to misunderstand the meaning.

It does not mean a mental image.

Not a mere idea.

Not something internal to our own minds.

It is not, according to the text, the intuition itself, something in our mind, but the object of the intuition, which is the appearance.

If I have an intuition of an apple in my hand, yes, there’s a mental state involved, an intuition, but the object of that mental state, what I am put in touch with by having that intuition, is the apple, is the “appearance.”

What if I’m dreaming of an apple, there is no apple, the Kant would say, there is no intuition – because an intuition puts me in contact with an object -- there is no appearance.

I call that in the appearance which corresponds to sensation its matter, but that which allows the manifold of appearance to be ordered in certain relations I call the form of appearance. Since that within which
the sensations can alone be ordered and placed in a certain form cannot itself be in turn sensation, the matter of all appearance is only given to us a posteriori, but its form must all lie ready for it in the mind a priori, and can therefore be considered separately from all sensation.

I call all representations pure (in the transcendental sense) in which
nothing is to be encountered that belongs to sensation. Accordingly the
pure form of sensible intuitions in general is to be encountered in the
mind a priori, wherein all of the manifold of appearances is intuited in
certain relations. This pure form of sensibility itself is also called pure
intuition. So if I separate from the representation of a body that which the understanding thinks about it, such as substance, force, divisibility,
etc., as well as that which belongs to sensation, such as impenetrability,
hardness, color, etc., something from this empirical intuition is still left for me, namely extension and form. These belong to the pure intuition,
which occurs a priori, even without an actual object of the senses or sensation, as a mere form of sensibility in the mind.

VG: The pure intuitions are what the Transcendental Aesthetic is about. Kant is not going to be interested in anything empirical but our a priori knowledge and cognitions; meaning not sensation but sensibility will be in focus, the capacity for sensation, and what is waiting to be filled in by the matter that comes to us in the actual sensations.

I call a science of all principles of a priori sensibility the transcendental aesthetic. There must therefore be such a science, which constitutes the first part of the transcendental doctrine of elements, in opposition to that which contains the principles of pure thinking, and which is named transcendental logic.

In the transcendental aesthetic we will therefore first isolate sensi-
bility by separating off everything that the understanding thinks
through its concepts, so that nothing but empirical intuition remains.
Second, we will then detach from the latter everything that belongs to
sensation, so that nothing remains except pure intuition and the mere
form of appearances, which is the only thing that sensibility can make
available a priori. In this investigation it will be found that there are two
pure forms of sensible intuition as principles a of a priori cognition,
namely space and time, with the assessment of which we will now be
concerned.
 

The Transcendental Aesthetic
First Section
On space.

Metaphysical exposition of this concept.
 

By means of outer sense (a property of our mind) we represent to
ourselves objects as outside us, and all as in space. In space their shape, magnitude, and relation to one another is determined, or determinable.
 

Inner sense, by means of which the mind intuits itself, or its inner state,
gives, to be sure, no intuition of the soul itself, as an object; yet it is
still a determinate form, under which the intuition of its inner state is
alone possible, so that everything that belongs to the inner determina
tions is represented in relations of time. Time can no more be intuited
externally than space can be intuited as something in us.

Now what are space and time?

Are they actual entities? Are they only determinations or relations of things, yet ones that would pertain to them even if they
were not intuited, or are they relations that only attach to the form of
intuition alone, and thus to the subjective constitution o f our mind,
without which these predicates could not be ascribed to any thing at all?
 

In order to instruct ourselves about this, we will expound the concept
of space first. l understand by exposition (expositio) the distinct
(even if not complete) representation of that which belongs to a con
cept; but the exposition is metaphysical when it contains that which
exhibits the concept as given a priori.
 

1) Space is not an empirical concept that has been drawn from outer experiences. For in order for certain sensations to be relateda to some
thing outside me (i.e., to something in another place in space from that
in which I find myself), thus in order for me to represent them as out
side <and next to> one another, thus not merely as different but as in
different places, the representation of space must already be their
ground. Thus the representation of space cannot be obtained from the
relations of outer appearance through experience, but this outer expe
rience is itself first possible only through this representation.
 

2) Space is a necessary representation, a priori, that is the ground of all outer intuitions. One can never represent that there is no space,
though one can very well think that there are no objects to be encoun-
tered in it. It is therefore to be regarded as the condition of the possi-bility of appearances, not as a determination dependent on them, and is
an a priori representation that necessarily grounds outer appearances.
 

3) Space is not a discursive or, as is said, general concept of rela-
tions of things in general, but a pure intuition. For, first, one can only represent a single space, and if one speaks of many spaces, one under
stands by that only parts of one and the same unique space. And these
parts cannot as it were precede the single all-encompassing space as its
components (from which its composition would be possible), but rather
are only thought in it. It is essentially single; the manifold in it, thus
also the general concept of spaces in general, rests merely on limita-
tions. From this it follows that in respect to it an a priori intuition
(which is not empirical) grounds all concepts of it. Thus also all geo
metrical principles, e.g., that in a triangle two sides together are always
greater than the third, are never derived from general concepts of line
and triangle, but rather are derived from intuition and indeed derived a
priori with apodictic certainty.
 

4) Space is represented as an infinite given magnitude. Now one
must, to be sure, think of every concept as a representation that is con- tained in an infinite set of different possible representations (as their
common mark), which thus contains these under itself; but no con-
cept, as such, can be thought as if it contained an infinite set of repre
sentations within itself. Nevertheless space is so thought (for all the
parts of space, even to infinity, are simultaneous). Therefore the origi-
nal representation of space is an a priori intuition, not a concept.

Transcendental exposition of the concept of space.
 

I understand by a transcendental exposition the explanation of a
concept as a principle from which insight into the possibility of other
synthetic a priori cognitions can be gained. For this aim it is required 1)
that such cognitions actually flow from the given concept, and 2) that
these cognitions are only possible under the presupposition of a given
way of explaining this concept.
 

Geometry is a science that determines the properties of space syn
thetically and yet a priori. What then must the representation of space
be for such a cognition of it to be possible? It must originally be intuition; for from a mere concept no propositions can be drawn that go be
yond the concept, which, however, happens in geometry (Introduction
V). But this intuition must be encountered in us a priori, i.e., prior to all
perception of an object, thus it must be pure, not empirical intuition.
For geometrical propositions are all apodictic, i.e., combined with con
sciousness of their necessity, e.g., space has only three dimensions; but
such propositions cannot be empirical or judgments of experience, nor
inferred from them (Introduction II).
 

Now how can an outer intuition inhabit the mind that precedes the
objects b themselves, and in which the concept of the latter can be de
termined a priori? Obviously not otherwise than insofar as it has its seat
merely in the subject, as its formal constitution for being affected by ob
jects and thereby acquiring immediate representation, i.e., intuition,
of them, thus only as the form of outer sense in general.
 

Thus our explanation alone makes the possibility of geometry as a
synthetic a priori cognition comprehensible. Any kind of explanation
that does not accomplish this, even if it appears to have some similar
ity with it, can most surely be distinguished from it by means of this
characteristic.
 

Conclusions from the above concepts.
 

a) Space represents no property at all of any things in themselves nor
any relation of them to each other, i.e., no determination of them that
attaches to objects themselves and that would remain even if one were
to abstract from all subjective conditions of intuition. For neither ab
solute nor relative determinations can be intuited prior to the existence
of the things to which they pertain, thus be intuited a priori.

b) Space is nothing other than merely the form of all appearances of
outer sense, i.e., the subjective condition of sensibility, under which
alone outer intuition is possible for us. Now since the receptivity of the
subject to be affected by objects necessarily precedes all intuitions of
these objects, it can be understood how the form of all appearances can
be given in the mind prior to all actual perceptions, thus a priori, and
how as a pure intuition, in which all objects must be determined, it can
contain principlesa of their relations prior to all experience.

We can accordingly speak of space, extended beings, and so on, only
from the human standpoint. If we depart from the subjective condition
under which alone we can acquire outer intuition, namely that through
which we may be affected by objects, then the representation of space
signifies nothing at all. This predicate is attributed to things only inso
far as they appear to us, i.e., are objects of sensibility. The constant form of this receptivity, which we call sensibility, is a necessary condition of all the relations within which objects can be intuited as outside us, and,
if one abstracts from these objects, it is a pure intuition, which bears the
name of space. Since we cannot make the special conditions of sensibil
ity into conditions of the possibility of things, but only of their appear
ances, we can well say that space comprehends all things that may
appear to us externally, but not all things in themselves, whether they
be intuited or not, or by whatever subject they may be intuited. For we
cannot judge at all whether the intuitions of other thinking beings are
bound to the same conditions that limit our intuition and that are uni
versally valid for us. If we add the limitation of a judgment to the con
cept of the subject, then the judgment is unconditionally valid. The
proposition: "All things are next to one another in space," is valid under
the limitation that these things be taken as objects of our sensible intu
ition. If here I add the condition to the concept and say "All things, as
outer intuitions, are next to one another in space," then this rule is valid
universally and without limitation. Our expositions accordingly teach
the reality (i.e., objective validity) of space in regard to everything that
can come before us externally as an object, but at the same time the ide
ality of space in regard to things when they are considered in them
selves through reason, i.e., without taking account of the constitution of
our sensibility. We therefore assert the empirical reality of space (with
respect to all possible outer experience), though to be sure its tran
scendental ideality, i.e., that it is nothing as soon as we leave aside the
condition of the possibility of all experience, and take it as something
that grounds the things in themselves.
 

Besides space, however, there is no other subjective representation related to something external that could be called a priori objective.
For one cannot derive synthetic a priori propositions from any such
representation, as one can from intuition in space. Strictly speak
ing, therefore, ideality does not pertain to them, although they coincide
with the representation of space in belonging only to the subjective
constitution of the kind of sense, e.g., of sight, hearing, and feeling,
through the sensations of colors, sounds, and warmth, which, however,
since they are merely sensations and not intuitions, do not in them
selves allow any object to be cognized, least of all a priori.

The aim of this remark is only to prevent one from thinking of illus-
trating the asserted ideality of space with completely inadequate exam
ples, since things like colors, taste, etc., are correctly considered not as
qualities of things but as mere alterations of our subject, which can even
be different in different people. For in this case that which is originally
itself only appearance, e.g., a rose, counts in an empirical sense as a
thing in itself, which yet can appear different to every eye in regard to
color. The transcendental concept of appearances in space, on the con
trary, is a critical reminder that absolutely nothing that is intuited in
space is a thing in itself, and that space is not a form that is proper to
anything in itself, but rather that objects in themselves are not known
to us at all, and that what we call outer objects are nothing other than
mere representations of our sensibility, whose form is space, but whose
true correlate, i.e., the thing in itself, is not and cannot be cognized
through them, but is also never asked after in experience.
 

The Transcendental Aesthetic
Second Section
On time.

Metaphysical exposition of the concept of time.
 

Time is 1) not an empirical concept that is somehow drawn from an
experience. For simultaneity or succession would not themselves come
into perception if the representation of time did not ground them a pri
ori. Only under its presupposition can one represent that several things
exist at one and the same time (simultaneously) or in different times
(successively) .
 

2 ) Time is a necessary representation that grounds all intuitions. In
regard to appearances in general one cannot remove time, though one can very well take the appearances away from time. Time is therefore
given a priori. In it alone is all actuality of appearances possible. The lat
ter could all disappear, but time itself (as the universal condition of their
possibility) cannot be removed.
 

3) This a priori necessity also grounds the possibility of apodictic principles of relations of time, or axioms of time in general. It has only
one dimension: different times are not simultaneous, but successive
(just as different spaces are not successive, but simultaneous). These
principles could not be drawn from experience, for this would yield nei-
ther strict universality nor apodictic certainty. We would only be able to
say: This is what common perception teaches, but not: This is how mat-
ters must stand. These principles are valid as rules under which alone
experiences are possible at all, and instruct us prior to them, not
through it.
 

4) Time is no discursive or, as one calls it, general concept, but a pure
form of sensible intuition. Different times are only parts of one and the
same time. That representation, however, which can only be given
through a single object, is an intuition. Further, the proposition that
different times cannot be simultaneous cannot be derived from a gen-
eral concept. The proposition is synthetic, and cannot arise from con-
cepts alone. It is therefore immediately contained in the intuition and
representation of time.

5) The infinitude of time signifies nothing more than that every de
terminate magnitude of time is only possible through limitations of a single time grounding it. The original representation time must there-
fore be given as unlimited. But where the parts themselves and every
magnitude of an object can be determinately represented only through
limitation, there the entire representation cannot be given through
concepts, for they contain only partial representations, but imme-
diate intuition must ground them.
 

Transcendental exposition of the concept of time.
 

I can appeal to no. 3 where, in order to be brief, I have placed that
which is properly transcendental under the heading of the metaphysical
exposition. Here I add further that the concept of alteration and, with it, the concept of motion (as alteration of place), is only possible
through and in the representation of time - that if this representation
were not a priori (inner) intuition, then no concept, whatever it might
be, could make comprehensible the possibility of an alteration, i.e., of a
combination of contradictorily opposed predicates (e.g., a thing's being
in a place and the not-being of the very same thing in the same place)
in one and the same object. Only in time can both contradictorily opposed determinations in one thing be encountered, namely succes
sively. Our concept of time therefore explains the possibility of as much
synthetic a priori cognition as is presented by the general theory of mo
tion, which is no less fruitful.

Conclusions from these concepts.
 

a) Time is not something that would subsist for itself or attach to things
as an objective determination, and thus remain if one abstracted from
all subjective conditions of the intuition of them; for in the first case it
would be something that was actual yet without an actual object. As far as the second case is concerned, however, time could not precede the
objects as a determination or order attaching to the things themselves
as their condition and be cognized and intuited a priori through syn
thetic propositions. But the latter, on the contrary, can very well occur
if time is nothing other than the subjective condition under which all
intuitions can take place in us. For then this form of inner intuition can
be represented prior to the objects, thus a priori.
 

b) Time is nothing other than the form of inner sense, i.e., of the in
tuition of our self and our inner state. For time cannot be a determina-
tion of outer appearances; it belongs neither to a shape or a position,
etc., but on the contrary determines the relation of representations in
our inner state. And just because this inner intuition yields no shape we
also attempt to remedy this lack through analogies, and represent the
temporal sequence through a line progressing to infinity, in which the
manifold constitutes a series that is of only one dimension, and infer
from the properties of this line to all the properties of time, with the
sole difference that the parts of the former are simultaneous but those
of the latter always exist successively. From this it is also apparent that
the representation of time is itself an intuition, since all its relations can
be expressed in an outer intuition.
 

c) Time is the a priori formal condition of all appearances in general.
Space, as the pure form of all outer intuitions, is limited as an a priori condition merely to outer intuitions. But since, on the contrary, all rep
resentations, whether or not they have outer things as their object, nev
ertheless as determinations of the mind themselves belong to the inner
state, while this inner state belongs under the formal condition of inner
intuition, and thus of time, so time is an a priori condition of all ap
pearance in general, and indeed the immediate condition of the inner
intuition (of our souls), and thereby also the mediate condition of outer
appearances. If I can say a priori: all outer appearances are in space and determined a priori according to the relations of space, so from the
principle of inner sense I can say entirely generally: all appearances in
general, i.e., all objects of the senses, are in time, and necessarily stand
in relations of time.
 

If we abstract from our way of internally intuiting ourselves and by
means of this intuition also dealing with all outer intuitions in the
power of representation, and thus take objects as they may be in them
selves, then time is nothing. It is only of objective validity in regard to
appearances, because these are already things that we take as objects of our senses; but it is no longer objective if one abstracts from the sen- sibility of our intuition, thus from that kind of representation that is pe-
culiar to us, and speaks of things in general. Time is therefore merely
a subjective condition of our (human) intuition (which is always sensi-
ble, i.e., insofar as we are affected by objects), and in itself, outside the
subject, is nothing. Nonetheless it is necessarily objective in regard to
all appearances, thus also in regard to all things that can come before us
in experience. We cannot say all things are in time, because with the
concept of things in general abstraction is made from every kind of in- tuition of them, but this is the real condition under which time belongs
to the representation of objects. Now if the condition is added to the
concept, and the principle says that all things as appearances (objects of
sensible intuition) are in time, then the principle has its sound objective
correctness and a priori universality.
 

Our assertions accordingly teach the empirical reality of time, i.e.,
objective validity in regard to all objects that may ever be given to our
senses. And since our intuition is always sensible, no object can ever be
given to us in experience that would not belong under the condition of
time. But, on the contrary, we dispute all claim of time to absolute re
ality, namely where it would attach to things absolutely as a condition
or property even without regard to the form of our sensible intuition.

Such properties, which pertain to things in themselves, can never be
given to us through the senses. In this therefore consists the transcen
dental ideality of time, according to which it is nothing at all if one ab-stracts from the subjective conditions of sensible intuition, and cannot
be counted as either subsisting or inhering in the objects in themselves
(without their relation to our intuition). Yet this ideality is to be com-
pared with the subreptions of sensation just as little as that of space is,
because in that case one presupposes that the appearance itself, in which these predicates inhere, has objective reality, which is here entirely ab sent except insofar as it is merely empirical, i.e., the object itself is re
garded merely as appearance: concerning which the above remark in
the previous sections is to be consulted.
 

Elucidation.
 

Against this theory, which concedes empirical reality to time but dis
putes its absolute and transcendental reality, insightful men have so
unanimously proposed one objection that I conclude that it must natu
rally occur to every reader who is not accustomed to these considera
tions. It goes thus: Alterations are real (this is proved by the change of
our own representations, even if one would deny all outer appearances
together with their alterations). Now alterations are possible only in
time, therefore time is something real. There is no difficulty in answer
ing. I admit the entire argument. Time is certainly something real,
namely the real form of inner intuition. It therefore has subjective real
ity in regard to inner experience, i.e., I really have the representation of
time and my determinations in it. It is therefore to be regarded really not as object but as the way of representing myself as object. But
if I or another being could intuit myself without this condition of sen
sibility, then these very determinations, which we now represent to our
selves as alterations, would yield us a cognition in which the repre
sentation of time and thus also of alteration would not occur at all. Its
empirical reality therefore remains as a condition of all our experiences.
Only absolute reality cannot be granted to it according to what has been
adduced above. It is nothing except the form of our inner intuition.*

* I can, to be sure, say: my representations succeed one another; but that only means that we are conscious of them as in a temporal sequence, i.e., according to the form of inner sense. Time is not on that account something in it self, nor any determination objectively adhering to things.

If one removes the special condition of our sensibility from it, then the
concept of time also disappears, and it does not adhere to the objects themselves, rather merely to the subject that intuits them.
 

The cause, however, on account of which this objection is so unani
mously made, and indeed by those who nevertheless know of nothing
convincing to object against the doctrine of the ideality of space,32 is this. They did not expect to be able to demonstrate the absolute reality
of space apodictically, since they were confronted by idealism, accord-
ing to which the reality of outer objects is not capable of any strict
proof: on the contrary, the reality of the object of our inner sense (of
myself and my state) is immediately clear through consciousness. The
former could have been a mere illusion, but the latter, according to
their opinion, is undeniably something real. But they did not consider
that both, without their reality as representations being disputed, nev
ertheless belong only to appearance, which always has two sides, one
where the object a is considered in itself (without regard to the way in
which it is to be intuited, the constitution of which however must for
that very reason always remain problematic), the other where the form
of the intuition of this object is considered, which must not be sought
in the object in itself but in the subject to which it appears, but which
nevertheless really and necessarily pertains to the representation of this
object.
 

Time and space are accordingly two sources of cognition, from
which different synthetic cognitions can be drawn a priori, of which es-pecially pure mathematics in regard to the cognitions of space and its
relations provides a splendid example. Both taken together are,
namely, the pure forms of all sensible intuition, and thereby make pos-
sible synthetic a priori propositions. But these a priori sources of cog-
nition determine their own boundaries by that very fact (that they are
merely conditions of sensibility), namely that they apply to objects
only so far as they are considered as appearances, but do not present
things in themselves. Those alone are the field of their validity, beyond
which no further objective use of them takes place. This reality of
space and time, further, leaves the certainty of experiential cognition
untouched: for we are just as certain of that whether these forms nec
essarily adhere to the things in themselves or only to our intuition of
these things. Those, however, who assert the absolute reality of space
and time, whether they assume it to be subsisting or only inhering,
must themselves come into conflict with the principlesb of experience.

For if they decide in favor of the first (which is generally the position
of the mathematical investigators of nature), then they must assume
two eternal and infinite self-subsisting non-entities (space and time),
which exist (yet without there being anything real) only in order to
comprehend everything real within themselves. If they adopt the sec-
ond position (as do some metaphysicians of nature), and hold space
and time to be relations of appearances (next to or successive to one
another) that are abstracted from experience though confusedly repre
sented in this abstraction, then they must dispute the validity or at least
the apodictic certainty of a priori mathematical doctrines in regard to
real things (e.g., in space), since this certainty does not occur a posteri
ori, and on this view the a priori concepts of space and time are only
creatures of the imagination, the origin of which must really be sought
in experience, out of whose abstracted relations imagination has made
something that, to be sure, contains what is general in them but that
cannot occur without the restrictions that nature has attached to
them. The first succeed in opening the field of appearances for math
ematical assertions.a However, they themselves become very confused
through precisely these conditions if the understanding would go be
yond this field. The second succeed, to be sure, with respect to the lat
ter, in that the representations of space and time do not stand in their
way if they would judge of objects not as appearances but merely in re
lation to the understanding; but they can neither offer any ground for
the possibility of a priori mathematical cognitions (since they lack a
true and objectively valid a priori intuition), nor can they bring the
propositions of experience into necessary accord with those assertions.
 

On our theory of the true constitution of these two original forms of
sensibility both difficulties are remedied.
 

Finally, that the transcendental aesthetic cannot contain more than
these two elements, namely space and time, is clear from the fact that
all other concepts belonging to sensibility, even that of motion, which
unites both elements, presuppose something empirical. For this pre
supposes the perception of something movable. In space considered in
itself there is nothing movable; hence the movable must be something
that is found in space only through experience, thus an empirical
datum. In the same way the transcendental aesthetic cannot count the
concept of alteration among its a priori data; for time itself does not
alter, but only something that is within time. For this there is required
the perception of some existence and the succession of its determina
tions, thus experience.

General remarks on the transcendental aesthetic
 

I. It will first be necessary to explain as distinctly as possible our
opinion in regard to the fundamental constitution of sensible cognition in general, in order to preclude all misinterpretation of it.
 

We have therefore wanted to say that all our intuition is nothing but
the representation of appearance; that the things that we intuit are not
in themselves what we intuit them to be, nor are their relations so con
stituted in themselves as they appear to us; and that if we remove our
own subject or even only the subjective constitution of the senses in
general, then all constitution, all relations of objectsb in space and time,
indeed space and time themselves would disappear, and as appearances they cannot exist in themselves, but only in us. What may be the case with objects in themselves and abstracted from all this receptivity of our sensibility remains entirely unknown to us. We are acquainted with nothing except our way of perceiving them, which is peculiar to us, and which therefore does not necessarily pertain to every being, though to be sure it pertains to every human being. We are concerned solely with this. Space and time are its pure forms, sensation in general its matter.
 

We can cognize only the former a priori, i.e., prior to all actual percep-
tion, and they are therefore called pure intuition; the latter, however, is
that in our cognition that is responsible for it being called a posteriori
cognition, i.e., empirical intuition. The former adheres to our sensibil-
ity absolutely necessarily, whatever sort of sensations we may have; the
latter can be very different. Even if we could bring this intuition of ours to the highest degree of distinctness we would not thereby come any
closer to the constitution of objects in themselves. For in any case we
would still completely cognize only our own way of intuiting, i.e., our
sensibility, and this always only under the conditions originally depend-
ing on the subject, space and time; what the objects may be in them-
selves would still never be known through the most enlightened
cognition of their appearance, which alone is given to us.
 

That our entire sensibility is nothing but the confused representation
of things, which contains solely that which pertains to them in them
selves but only under a heap of marks and partial representations that
we can never consciously separate from one another, is therefore a fal
sification of the concept of sensibility and of appearance that rendersthe entire theory of them useless and empty. The difference between an
indistinct and a distinct representation is merely logical, and does not
concern the content. Without doubt the concept of right that is used
by the healthy understanding contains the very same things that the
most subtle speculation can evolve out of it, only in common and prac
tical use one is not conscious of these manifold representations in these
thoughts.

Thus one cannot say that the common concept is sensible and
contains a mere appearance, for right cannot appear at all; rather its
concept lies in the understanding and represents a constitution (the
moral constitution) of actions that pertains to them in themselves. The
representation of a body in intuition, on the contrary, contains nothing
at all that could pertain to an object in itself, but merely the appearance
of something and the way in which we are affected by it; and this re
ceptivity of our cognitive capacity is called sensibility and remains
worlds apart from the cognition of the object in itself even if one might
see through to the very bottom of it (the appearance).
 

The Leibnizian-Wolffian philosophy has therefore directed all inves
tigations of the nature and origin of our cognitions to an entirely unjust
point of view in considering the distinction between sensibility and the
intellectual as merely logical, since it is obviously transcendental, and
does not concern merely the form of distinctness or indistinctness, but
its origin and content, so that through sensibility we do not cognize the
constitution of things in themselves merely indistinctly, but rather not
at all, and, as soon as we take away our subjective constitution, the rep
resented object with the properties that sensible intuition attributes to
it is nowhere to be encountered, nor can it be encountered, for it is just
this subjective constitution that determines its form as appearance.

We ordinarily distinguish quite well between that which is essentially
attached to the intuition of appearances, and is valid for every human
sense in general, and that which pertains to them only contingently be
cause it is not valid for the relationb of sensibility in general but only for
a particular situation or organization of this or that sense. And thus one
calls the first cognition one that represents the object in itself, but the
second one only its appearance. This distinction, however, is only em
pirical. If one stands by it (as commonly happens) and does not regard
that empirical intuition as in turn mere appearance (as ought to hap
pen), so that there is nothing to be encountered in it that pertains to
anything in itself, then our transcendental distinction is lost, and we be-lieve ourselves to cognize things in themselves, though we have noth-
ing to do with anything except appearances anywhere (in the world of
sense), even in the deepest research into its objects. Thus, we would certainly call a rainbow a mere appearance in a sun-shower, but would
call this rain the thing in itself, and this is correct, as long as we under-
stand the latter concept in a merely physical sense, as that which in uni-
versal experience and all different positions relative to the senses is
always determined thus and not otherwise in intuition. But if we con-
sider this empirical object in general and, without turning to its agree-
ment with every human sense, ask whether it (not the raindrops, since these, as appearances, are already empirical objects)a represents an object in itself, then the question of the relation of the representation to
the object is transcendental, and not only these drops are mere appear-
ances, but even their round form, indeed even the space through which
they fall are nothing in themselves, but only mere modifications or
foundationsb of our sensible intuition; the transcendental object, how-
ever, remains unknown to us.
 

The second important concern of our transcendental aesthetic is that
it not merely earn some favor as a plausible hypothesis, but that it be as
certain and indubitable as can ever be demanded of a theory that is to
serve as an organon. In order to make this certainty fully convincing we
will choose a case in which its validity can become obvious <and that can serve to make that which has been adduced in § 3 even more clear.
 

Thus, if it were to be supposed that space and time are in themselves
objective and conditions of the possibility of things in themselves, then
it would be shown, first, that there is a large number of a priori apodic
tic and synthetic propositions about both, but especially about space,
which we will therefore here investigate as our primary example. Since
the propositions of geometry are cognized synthetically a priori and
with apodictic certainty, I ask: Whence do you take such propositions, and on what does our understanding rely in attaining to such absolutely
necessary and universally valid truths? There is no other way than
through concepts or through intuitions, both of which, however, are
given, as such, either a priori or a posteriori. The latter, namely empiri-
cal concepts, together with that on which they are grounded, empirical
intuition, cannot yield any synthetic proposition except one that is also
merely empirical, i.e., a proposition of experience; thus it can never
contain necessity and absolute universality of the sort that is neverthe-
less characteristic of all propositions of geometry. Concerning the first
and only means for attaining to such cognitions, however, namely through mere concepts or a priori intuitions, it is clear that from mere
concepts no synthetic cognition but only merely analytic cognition can
be attained. Take the proposition that with two straight lines no space
at all can be enclosed, thus no figure is possible, and try to derive it from
the concept of straight lines and the number two; or take the proposi
tion that a figure is possible with three straight lines, and in the same
way try to derive it from these concepts. All of your effort is in vain, and
you see yourself forced to take refuge in intuition, as indeed geometry
always does. You thus give yourself an object in intuition; but what kind
is this, is it a pure a priori intuition or an empirical one? If it were the
latter, then no universally valid, let alone apodictic proposition could
ever come from it: for experience can never provide anything of this
sort. You must therefore give your object a priori in intuition, and
ground your synthetic proposition on this. If there did not lie in you a
faculty for intuiting a priori; if this subjective condition regarding form
were not at the same time the universal a priori condition under which
alone the object a of this (outer) intuition is itself possible; if the object
(the triangle) were something in itself without relation to your subject:
then how could you say that what necessarily lies in your subjective con
ditions for constructing a triangle must also necessarily pertain to the
triangle in itself? for you could not add to your concept (of three lines)
something new (the figure) that must thereby necessarily be encoun
tered in the object, since this is given prior to your cognition and not
through it. If, therefore, space (and time as well) were not a mere form
of your intuition that contains a priori conditions under which alone
things could be outer objects for you, which are nothing in themselves
without these subjective conditions, then you could make out absolutely
nothing synthetic and a priori about outer objects. It is therefore indu
bitably certain and not merely possible or even probable that space and
time, as the necessary conditions of all (outer and inner) experience, are
merely subjective conditions of all our intuition, in relation to which
therefore all objects are mere appearances and not things given for
themselves in this way; about these appearances, further, much may be
said a priori that concerns their form but nothing whatsoever about the
things in themselves that may ground them.
 

II. For confirmation of this theory of the ideality of outer as well as
inner sense, thus of all objectsd of the senses, as mere appearances, this comment is especially useful: that everything in our cognition that be
longs to intuition (with the exception, therefore, of the feeling of plea-sure and displeasure and the will, which are not cognitions at all) con-
tains nothing but mere relations,a of places in one intuition (extension),
alteration of places (motion), and laws in accordance with which this al-teration is determined (moving forces). But what is present in the place,
or what it produces in the things themselves besides the alteration of
place, is not given through these relations. Now through mere relations
no thing in itself is cognized; it is therefore right to judge that since
nothing is given to us through outer sense except mere representations
of relation, outer sense can also contain in its representation only the
relation of an object to the subject, and not that which is internal to the
objectb in itself. It is exactly the same in the case of inner sense. It is
not merely that the representations of outer sense make up the proper
material with which we occupy our mind, but also the time in which we
place these representations, which itself precedes the consciousness of
them in experience and grounds the way in which we place them in
mind as a formal condition, already contains relations of succession, of
simultaneity, and of that which is simultaneous with succession (of that
which persists). Now that which, as representation, can precede any act
of thinking something is intuition and, if it contains nothing but rela-
tions, it is the form of intuition, which, since it does not represent any-
thing except insofar as something is posited in the mind, can be nothing
other than the way in which the mind is affected by its own activity,
namely this positing of its representation, thus the way it is affected
through itself, i.e., it is an inner sense as far as regards its form.
 

Everything that is represented through a sense is to that extent always
appearance, and an inner sense must therefore either not be admitted at
all or else the subject, which is the object of this sense, can only be rep
resented by its means as appearance, not as it would judge of itself if its
intuition were mere self-activity, i.e., intellectual. Any difficulty in this
depends merely on the question how a subject can internally intuit it-
self; yet this difficulty is common to every theory. Consciousness of it-
self (apperception) is the simple representation of the I, and if all of the
manifold in the subject were given self-actively through that alone,
then the inner intuition would be intellectual. In human beings this
consciousness requires inner perception of the manifold that is an
tecedently given in the subject, and the manner in which this is given in
the mind without spontaneity must be called sensibility on account of
this difference. If the faculty for becoming conscious of oneself is to
seek out (apprehend) that which lies in the mind, it must affect the latter, and it can only produce an intuition of itself in such a way, whose
form, however, which antecedently grounds it in the mind, determines
the way in which the manifold is together in the mind in the represen-
tation of time; there it then intuits itself not as it would immediately
self-actively represent itself, but in accordance with the way in which it
is affected from within, consequently as it appears to itself, not as it is.
 

III. If I say: in space and time intuition represents both outer objectsa
as well as the self-intuition of the mind as each affects our senses, i.e.,
as it appears, that is not to say that these objects would be a mere illu
sion. For in the appearance the objects indeed even propertiesd that
we attribute to them, are always regarded as something really given,
only insofar as this property depends only on the kind of intuition of the
subject in the relation e of the given object to it then this object as ap
pearance is to be distinguished from itself as object! in itself. Thus I
do not say that bodies merely seemg to exist outside me or that my soul
only seemsh to be given ifI assert that the quality of space and time - in
accordance with which, as condition of their existence, I posit both of
these - lies in my kind of intuition and not in these objectsi in them
selves. It would be my own fault if I made that which I should count as
appearance into mere illusion. *

*The predicates of appearance can be attributed to the object} in itself, in relation to our sense, e.g., the red color or fragrance to the rose; but the illusion can never be attributed to the object as predicate, precisely because that would be to attribute to the objectk for itself what pertains to it only in relation to the senses or in general to the subject, e.g., the two handles that were origi nally attributed to Saturn. VVhat is not to be encountered in the object in itself at all, but is always to be encountered in its relation to the subject and is inseparable from the representation of the object, is appearance, and thus the predicates of space and of time are rightly attributed to the objects of the senses as such, and there is no illusion in this. On the contrary, if I attribute the redness to the rose in itself, the handles to Saturn or extension to all outer objects in themselves, without looking to a determinate relation of these ob jects to the subject and limiting my judgment to this, then illusion first arises.
 

But this does not happen according to our principle of the ideality of all of our sensible intuitions; rather, if one ascribes objective reality to those forms of representation then one cannot avoid thereby transforming everything into mere illusion.
 

For if one regards space and time as properties that, as far as their pos
sibility is concerned, must be encountered in things in themselves, and
reflects on the absurdities in which one then becomes entangled, be
cause two infinite things that are neither substances nor anything really
inhering in substances must nevertheless be something existing, indeed
the necessary condition of the existence of all things, which also remain even if all existing things are removed; then one cannot well blame the
good Berkeley if he demotes bodies to mere illusion; indeed even our
own existence, which would be made dependent in such a way on the
self-subsisting reality of a non-entity such as time, would be trans
formed along with this into mere illusion; an absurdity of which no one
has yet allowed himself to be guilty.
 

IV. In natural theology, where one conceives of an object that is not
only not an object of intuition for us but cannot even be an object of
sensible intuition for itself, one is careful to remove the conditions of
time and space from all of its intuition (for all of its cognition must be
intuition and not thinking, which is always proof of limitations). But
with what right can one do this if one has antecedently made both of
these into forms of things in themselves, and indeed ones that, as a pri
ori conditions of the existence of things, would remain even if one re
moved the things themselves? - for as conditions of all existence in
general they would also have to be conditions of the existence of God.
If one will not make them into objective forms of all things, then no al-ternative remains but to make them into subjective forms of our kind of
outer as well as inner intuition, which is called sensible because it is not
original, i.e., one through which the existence of the objectb of intu-
ition is itself given (and that, so far as we can have insight, can only per-
tain to the original being); rather it is dependent on the existence of the
object,c thus it is possible only insofar as the representational capacity of the subject is affected through that.
 

It is also not necessary for us to limit the kind of intuition in space and time to the sensibility of human beings; it may well be that all finite
thinking beings must necessarily agree with human beings in this re
gard (though we cannot decide this), yet even given such universal va
lidity this kind of intuition would not cease to be sensibility, for the very
reason that it is derived (intuitus derivativus), not original (intuitius or,
inarius), thus not intellectual intuition, which for the ground already
adduced seems to pertain only to the original being, never to one that
is dependent as regards both its existence and its intuition (which de
termines its existence in relation to given objects); although the last re
mark must be counted only as an illustration of our aesthetic theory and
not as a ground of its proof.
 

Conclusion of the Transcendental Aesthetic.
 

Here we now have one of the required pieces for the solution of the
general problem of transcendental philosophy - how are synthetic a
priori propositions possible? - namely pure a priori intuitions, space
and time, in which, if we want to go beyond the given concept in an a
priori judgment, we encounter that which is to be discovered a priori and
synthetically connected with it, not in the concept but in the intuition
that corresponds to it; but on this ground such a judgment never ex
tends beyond the objects of the senses and can hold only for objects of
possible experience.