those of outer sense. Both are appearances, and neither can
be identified with the absolutely real. As Kant argues later
in the Critique? inner processes are not known with any
greater certainty or immediacy than are outer objects ; the
reality of time as subjective proves its unreality in relation to
things in themselves. The statement that the constitution of
* W. x. pp. 128-9. Italics not in Kant. Kant is entirely justified in protesting
against the view that in denying things in themselves to be in time he is asserting
that they remain eternally the same with themselves. To make a dancer preserve
one and the same posture is not to take him out of time, but to bring home to him
the reality of time in an extremely unpleasant manner. Duration is one of the
modes of time.
2 This is Kant's reply to Mendelssohn's objection (December 1770, W. x.
p. no): "Succession is at least a necessary condition of the representations of
finite spirits. Now the finite spirits are not only subjects but also objects
of representations, both for God and for our fellow-men. The succession must
therefore be regarded as something objective."
3 Cf. A 277 = B 333 : " It is not given to us to observe even our own mind
with any intuition but that of our inner sense."
4 Quoted by Vaihinger, ii. p. 406.
6 In the fourth Paralogism, A 366, and in the Refutation of Idealism, B 274.
THE TRANSCENDENTAL AESTHETIC
things in themselves is " problematic " is an exceptional mode
of expression for Kant. Usually as indeed throughout the
whole context of this passage l he asserts that though things
in themselves are unknowable, we can with absolute certainty
maintain that they are neither in space nor in time. Upon
this point we have already dwelt in discussing Trendelen-
burg's controversy with Fischer. 2
Third Paragraph. The third and fourth paragraphs of this
section ought to have had a separate heading. They sum-
marise the total argument of the Aesthetic in regard to space
as well as time, distinguish its tenets from those of Newton
and of Leibniz, and draw a general conclusion. The summary
follows the strict synthetic method. The opening sentences
illustrate Kant's failure to distinguish between the problems
of pure and of applied mathematics, and also show how
completely he tends to conceive mathematics as typified by
geometry. The criticism of alternative views traverses the
ground of the famous controversy between Leibniz and
Clarke. Their Streitschriften were, as we have good cir-
cumstantial grounds for believing, 3 a chief influence in the
development of Kant's own views. Kant, who originally
held the Leibnizian position, was by 1768* more or less con-
verted to the Newtonian teaching, and in the Dissertation
of 1770 developed his subjectivist standpoint with the con-
scious intention of retaining the advantages while remedying
the defects of both alternatives. 5 For convenience we may
limit the discussion to space, (a] The view propounded by
Newton, and defended by Clarke, is that space has an
existence in and by itself, independent alike of the mind
which apprehends it and of the objects with which it is filled.
(<) The view held by Leibniz is that space is an empirical
concept abstracted from our confused sense-experience of
the relations of real things. 6
The criticism of (a) is twofold. First, it involves belief
1 Cf. A42 = B 59. 2 Above, pp. 113-14. 3 Cf. Vaihinger, ii. p. 114.
4 The date of Kant's Von dem ersten Grunde des Unterschiedes der Gegenden
5 Cf. below, p. 161 ff.
6 Cf. Dissertation, 15 D : " Those who defend the reality of space conceive
it either as an absolute and immense receptacle of possible things a view which
appeals not only to the English [thinkers] but to most geometricians or they
contend that it is nothing but a relation holding between existing things, which
must vanish when the things are removed, and which is thinkable only in actual
things. This latter is the teaching of Leibniz and of most of our countrymen."
That the account of Leibniz's teaching given in the paragraphs under consideration
is not altogether accurate, need hardly be pointed out. Kant, following his
usual method in the discussion of opposing systems, is stating what he regards
as being the logical consequences of certain of Leibniz's tenets, rather than his
CRITICISMS OF NEWTON AND LEIBNIZ 141
in an eternal and infinite Uniting. Secondly, it leads to meta-
physical difficulties, especially in regard to the existence of
God. If space is absolutely real, how is it to be reconciled
with the omnipresence of God ? Newton's view of space as
the sensorium Dei can hardly be regarded as satisfactory.
The objection to () is that it cannot account for the apo-
dictic certainty of geometry, nor guarantee its application
to experience. The concept of space, when regarded as of
sensuous origin, is something that may distort (and according
to the Leibnizian teaching does actually distort) what it pro-
fesses to represent, and is something from which restrictions
that hold in the natural world have been omitted. 1 As
empirical, it cannot serve as basis for the universal and neces-
sary judgments of mathematical science. 2
The first view has, however, the advantage of keeping
the sphere of appearances open for mathematical science.
As space is infinite and all -comprehensive, its laws hold
universally. The second view has the advantage of not sub-
jecting reality to space conditions. These advantages are
retained, while the objections are removed, by the teaching
of the Aesthetic.
1 Cf. A 275-6 = 6 331-2 : " Leibniz conceived space as a certain order in the
community of substances, and time as the dynamical sequence of their states.
But. that which both seem to possess as proper to themselves, in independence
of things, he ascribed to the confused character of their concepts, asserting this
confusion to be the reason why what is a mere form of dynamical relations has
come to be regarded as a special intuition, self-subsistent and antecedent to
the things themselves. Thus space and time were [for Leibniz] the intelligible
form of the connection of things (substances and their states) in themselves. " Cf.
also Prolegomena, 13, Anm. i.
2 Kant has stated that both views conflict with "the principles of experience."
But his criticisms are not altogether on that line. The statement strictly applies
only to his criticism of the Leibnizian view. Cf. Dissertation, 15 D : "That
first inane invention of reason, assuming as it does the existence of true infinite
relations in the absence of all interrelated entities, belongs to the realm of fable.
But those who adopt the other view fall into a much worse error. For whereas the
former place an obstacle in the way only of certain rational concepts, i.e. concepts
that concern noumena, and which also in themselves are extremely obscure bearing
upon questions as to the spiritual world, omnipresence, etc., the latter set them-
selves in direct antagonism to the phenomena themselves and to geometry, the
most faithful interpreter of all phenomena. For not to dwell upon. the obvious
circle in which they necessarily become involved in defining space they cast
geometry down from its position at the highest point of certitude, and throw it back
into the class of those sciences the principles of which are empirical. For if all
modifications of space are derived only through experience from external relations,
geometrical axioms can have only comparative universality, like that acquired
through induction, in other words, such as extends only as far as observation has
gone. They cannot lay claim to any necessity save that of being in accordance
with the established laws of nature, nor to any precision except of the artificial
sort, resting upon assumptions. And as happens in matters empirical, the
possibility is not excluded that a space endowed with other original modifications,
and perhaps even a rectilineal figure enclosed by two lines, may sometime be
discovered." Cf. above, p. 114; below, p. 290.
H2 THE TRANSCENDENTAL AESTHETIC
Kant further criticises the former view in A 46 ff. = B 64 fT.
There is no possibility of accounting for the a priori synthetic
judgments of geometry save by assuming that space is the
pure form of outer intuition. For though the Newtonian
view will justify the assertion that the laws of space hold
universally, it cannot explain how we come to know them
a priori. And assuming, as Kant constantly does, that space
cannot be both an a priori form of intuition and also
independently real, he concludes that it is the former only.
In B 71 Kant also restates the metaphysical difficulties
to which the Newtonian view lies open. In natural theology
we deal with an existence which can never be the object
of sensuous intuition, and which has to be freed from all
conditions of space and time. This is impossible if space is
so absolutely real that it would remain though all created
things were annihilated.
Fourth Paragraph. Space and time are the only two
forms of sensibility ; all other concepts belonging to the
senses, such as motion and change, are empirical. 1 As Kant
has himself stated, no reason can be given why space and
time are the sole forms of our possible intuition :
"Other forms of intuition than space and time, . . . even if they
were possible, we cannot render in any way conceivable and com-
prehensible to ourselves, and even assuming that we could do so,
they still would not belong to experience, the only kind of knowledge
in which objects are given to us." " 2
The further statement, 3 frequently repeated in the Critique,
that time itself does not change, but only what is in time, 4
indicates the extent to which Kant has been influenced by
the Newtonian receptacle view. As Bergson very justly
points out, time, thus viewed as a homogeneous medium, is
really, being conceived on the analogy of space. " It is
merely the phantom of space obsessing the reflective con-
1 In B 155 n. Kant distinguishes between motion of an object in space, and
motion as generation of a geometrical figure. The former alone involves ex-
perience ; the latter is a pure act of the productive imagination, and belongs not
only to geometry but also to transcendental philosophy. This note, as Erdmann
has pointed out (JCHticistnuS, pp. 115, 168), was introduced by Kant into the
second edition as a reply to a criticism of Schiitz. The distinction as thus drawn
is only tenable on the assumption of a pure manifold distinct from the manifold
2 A 230 = 6 283. Cf. above, pp. 57, 118; below, pp. 185-6, 257.
3 A 41 = B 58. 4 Cf. below, pp. 359-60.
6 Les Donntes Immediate*, p. 75.
LEIBNIZ'S VIEW OF SENSIBILITY 143
GENERAL OBSERVATIONS ON THE
I. First Paragraph. " To avoid all misapprehension "
Kant proceeds to state "as clearly as possible" his view of
sensuous knowledge. With this end in view he sets himself
to enforce two main points : (a) that as space and time are
only forms of sensibility, everything apprehended is only
appearance ; (#) that this is not a mere hypothesis but is
completely certain. Kant expounds (a) indirectly through
criticism of the opposing views of Leibniz and of Locke. But
before doing so he makes in the next paragraph a twofold
statement of his own conclusions.
Second Paragraph. This paragraph states (a) that through
intuition we can represent only appearances, not things in
themselves, and () that the appearances thus known exist
only in us. Both assertions have implications, the discussion
of which must be deferred to the Analytic. The mention of
the " relations of things by themselves " may, as Vaihinger
suggests, 1 be a survival from the time when (as in the Dis-
sertation 2 ) Kant sought to reduce spatial to dynamical
relations. The assertion that things in themselves are com-
pletely unknown to us goes beyond what the Aesthetic can
establish and what Kant here requires to prove. His present
thesis is only that no knowledge of things in themselves can
be acquired either through the forms of space and time or
through sensation ; space and time are determined solely by
our pure sensibility, and sensations by our empirical sensi-
bility. Failure to recognise this is, in Kant's view, one of the
chief defects of the Leibnizian system.
Third and Fourth Paragraphs. Criticism of the Leibniz-Wolff
Interpretation of Sensibility and of Appearance. Leibniz vitiates
both conceptions. Sensibility does not differ from thought
in clearness but in content. It is a difference of kind. 3 They
originate in different sources, and neither can by any trans-
formation be reduced to the other.
" Even if an appearance could become completely transparent to
us, such knowledge would remain toto coelo different from knowledge
of the object in itself." 4 "Through observation and analysis of
appearances we penetrate to the secrets of nature, and no one can say
how far this may in time extend. . . . [But however far we advance, we
1 ii. p. 446. 2 4 and 27>
3 Cf. Ueber eine Entdeckung, etc. : W. viii. p. 220.
144 THE TRANSCENDENTAL AESTHETIC
shall never be able by means of] so ill-adapted an instrument of in-
vestigation [as our sensibility] to find anything except still other
appearances, the non- sensuous cause of which we yet long to
We should still know only in terms of the two inalienable
forms of our sensibility. 2 The dualism of thought and sense
can never be transcended by the human mind. By no exten-
sion of its sphere or perfecting of its insight can sensuous
knowledge be transformed into a conceptual apprehension of
purely intelligible entities.
Leibniz's conception of appearances as things in them-
selves confusedly apprehended is equally false, and for the
same reasons. 3 Appearance and reality are related as distinct
existences, each of which has its own intrinsic character and
content. Through the former there can be no hope of pene-
trating to the latter. Appearance is subjective in matter as
well as in form. For Leibniz our knowledge of appearances
is a confused knowledge of things in themselves. Properly
viewed, it is the apprehension, whether distinct or confused,
of objects which are never things in themselves. Sense-
knowledge, such as we obtain in the science of geometry, has
often the highest degree of clearness. Conceptual apprehen-
sion is all too frequently characterised by obscurity and
This criticism of Leibniz, as expounded in these two
paragraphs, is thoroughly misleading if taken as an adequate
statement of Kant's view of the relations between sense and
understanding, appearance and reality. These paragraphs
are really a restatement of a passage in the Dissertation.
"It will thus be seen that we express the nature of the sensuous
very inappropriately when we assert that it is the more confusedly
known, and the nature of the intellectual when we describe it as the dis-
tinctly known. For these are merely logical distinctions, and obviously
have nothing to do with the given facts which underlie all logical
comparison. The sensuous may be absolutely distinct, and the
intellectual extremely confused. That is shown on the one hand in
geometry, the prototype of sensuous knowledge, and on the other in
metaphysics, the instrument of all intellectual enquiry. Every one
knows how zealously metaphysics has striven to dispel the mists of
confusion which cloud the minds of men at large and yet has not
1 A 277 = B 334. Cf. A 278-9 = 6 335-6.
2 When Kant says that the distinction is not logical (that of relative clearness
and obscurity) but transcendental, the latter term is taken as practically equivalent
to epistemological. It does not mean 'relating to \hzapriori? but relating to
transcendental philosophy, just as logical here means relating to logic. Cf.
Vaihinger, ii. p. 452. 3 Cf. A 270 ff. = B 326 ff.
THE CRITICAL VIEW OF APPEARANCES 145
always attained the happy results of the former science. Neverthe-
less each of these kinds of knowledge preserves the mark of the stock
from which it has sprung. The former, however distinct, is on
account of its origin entitled sensuous, while the latter, however
confused, remains intellectual as e.g. the moral concepts, which are
known not by way of experience, but through the pure intellect itself.
I fear, however, that Wolff by this distinction between the sensuous
and the intellectual, which for him is merely logical, has checked,
perhaps wholly (to the great detriment of philosophy), that noblest
enterprise of antiquity, the investigation of the nature of phenomena
and noumena, turning men's minds from such enquiries to what are
very frequently only logical subleties." *
The paragraphs before us give expression only to what is
common to the Dissertation and to the Critique, and do so
entirely from the standpoint of the Dissertation. Thus the
illustration of the conception of " right " implies that things in
themselves can be known through the understanding. The
conception, as Kant says, represents " a moral property which
belongs to actions in and by themselves." Similarly, in
distinguishing the sensuous from " the intellectual," he says
that through the former we do not apprehend things in
themselves, thus implying that things in themselves can be
known through the pure intellect. The view developed in
the Analytic, alike of sensibility and of appearance, is
radically different. Sensibility and understanding may have
a common source ; and both are indispensably necessary
for the apprehension of appearance. Neither can function
save in co - operation with the other. Appearance does
not differ from reality solely through its sensuous content
and form, but also in the intellectual order or dispensation to
which it is subject. But in the very act of thus deepening the
gulf between appearance and reality by counting even under-
standing as contributing to the knowledge only of the former,
he was brought back to a position that has kinship with the
Leibnizian view of their interrelation. Since understanding
is just as essential as sensibility to the apprehension of
appearances, and since understanding differs from sensibility
in the universality of its range, it enables us to view appear-
ances in their relation to ultimate reality, and so to apprehend
them as being, however subjective or phenomenal, ways in
which the thing in itself presents itself to us. Such a view
is, however, on Kant's principles, quite consistent with the
further contention, that appearance does not differ from reality
in a merely logical manner. Factors that are peculiar to the
*ealm of appearance have intervened to transform the real ;
1 7 (I read antem for atttor). Cf. below, p. 187.
H6 THE TRANSCENDENTAL AESTHETIC
and in consequence even completed knowledge of the pheno-
menal if such can be conceived as possible would not be
equivalent to knowledge of things in themselves.
Fifth Paragraph. Criticism of Locke's View of Appearance.
This paragraph discusses Locke's doctrine l that the secondary
qualities are subjective, and that in the primary qualities we
possess true knowledge of things in themselves. The distinc-
tion is drawn upon empirical grounds, namely, that while certain
qualities are uniform for more than one sense, and belong to
objects under all conditions, others are peculiar to the different
senses, and arise only through the accidental relation of objects
to the special senses. 2 This distinction is, Kant says, entirely
justified from the physical standpoint. 3 A rainbow is an
appearance of which the raindrops constitute the true empirical
reality. But Locke and his followers interpret this distinction
wrongly. They ignore the more fundamental transcendental
(i.e. metaphysical) distinction between empirical reality and
the thing in itself. From the transcendental standpoint the
raindrops are themselves merely appearance. Even their
round shape, and the very space in which they fall, are only
modifications of our sensuous intuition. The ' transcendental
object ' 4 remains unknown to us.
When Kant thus declares that the distinction between
primary and secondary qualities, is justified (richtig] from the
physical standpoint, he is again 5 speaking from a phenomen-
alist point of view. And it may be noted that in develop-
ing his transcendental distinction he does not describe the
raindrops as mere representations. His phrase is much more
indefinite. They are " modifications or fundamental forms
(Grundlagen) of our sensuous intuition."
Kant does not here criticise the view of sensibility which
underlies Locke's view of appearance. But he does so in
A 271 = B 327, completing the parallel and contrast between
Leibniz and Locke.
" Leibniz intellectualised appearances, just as Locke, according to
his system of noogony (if I may be allowed these expressions), sensual-
isedall concepts of the understanding, i.e. interpreted them as simply
empirical or abstracted concepts of reflection. Instead of interpret-
ing understanding and sensibility as two quite different sources of
representations, which yet can supply objectively valid judgments of
1 Cf. Prolegomena, 13, Remark II.
~ Cf. above, pp. 120-1. * Cf. A 257 = 6 313.
4 A 46 = B 63. This is the first occurrence in the Critique of the phrase
transcendental object. Transcendental is employed as synonymous with tran
scendent. Cf. below, p. 204 ff.
5 Cf. above, pp. 120-2.
THE IDEALITY OF APPEARANCES 147
things only in conjunction with each other, each of these great men
holds only to one of the two, viewing it as in immediate relation to
things in themselves. The other faculty is regarded as serving only
to confuse or to order the representations which this selected faculty
Proof that the above View of Space and Time is not a mere
Hypothesis, but completely certain. 2 The proof, which as here
recapitulated and developed follows the analytic method, has
already been considered in connection with A 39 = B 56. It
proceeds upon the assumption that space cannot be both an
a priori form of intuition and also independently real. The
argument as a whole lacks clearness owing to Kant's failure
to distinguish between the problems of pure and applied
geometry, between pure intuition and form of intuition.
This is especially obvious in the very unfortunate and mis-
leading second application of the triangle illustration. 3
Kant's tendency to conceive mathematical science almost
exclusively in terms of geometry is likewise illustrated.
"There is in regard to both [space and time] a large number of
a priori apodictic and synthetic propositions. This is especially true
of space, which for this reason will be our chief illustration in this
enquiry." 4 /QJ^
II. Paragraphs added in the Second Edition. 6 Kant proceeds
to offer further proof of the ideality of the appearances (a) of
outer and () of inner sense. Such proof he finds in the fact
that these appearances consist solely of relations, (a) Outer
appearances reduce without remainder to relations of position
in intuition (i.e. of extension), of change of position (motion),
and to the laws which express in merely relational terms the
motive forces by which such change is determined. What it
is that is thus present in space, or what the dynamic agencies
may be to which the motion is due, is never revealed. But a
real existent (Sache an sick] can never be known through
mere relations. Outer sense consequently reveals through its
representations only the relation of an object to the subject,
not the intrinsic inner nature of the object in itself (Object an
sich}. Kant's avoidance of the term Ding an sich may be noted. 6
] A27i = B327. 2 A46-9=B 63-6.
3 A 48 = B 65-6. Vaihinger (ii. pp. 470-2) gives what appears to be a sufficient
explanation of what Kant had in mind in its employment.
4 A 46=6 64. Cf. Dissertation, 15 C. In the concluding sentence of the
first edition's Aesthetic, Kant for the first time uses the singular Ding an sich in
place of the more usual Dinge an sich and also refers to it in problematic terms as
what may underlie appearances. 5 B 66-73.
6 a does not contain anything not to be found elsewhere in the first edition.
It is a restatement of A 265 ff. =B 321 ff., A 274 = 6 330, A 277 ff. =B 333 ff.,
A 283-5 = B 339-41.
148 THE TRANSCENDENTAL AESTHETIC
(V) The same holds true of inner sense, not only because
the representations of outer sense constitute its proper
(eigent lichen) material, but also because time, in which these