Critique of Pure Reason


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WE have already entitled dialectic in general a logic of illu-
sion. This does not mean a doctrine of probability; for prob-
ability is truth, known however on insufficient grounds, and
the knowledge of which, though thus imperfect, is not on that
account deceptive; and such doctrine, accordingly, is not to be
separated from the analytic part of logic. Still less justification
have we for regarding appearance and illusion as being identi-
cal. For truth or illusion is not in the object, in so far as it is
intuited, but in the judgment about it, in so far as it is thought. 
It is therefore correct to say that the senses do not err -- not
because they always judge rightly but because they do not
judge at all. Truth and error, therefore, and consequently also
illusion as leading to error, are only to be found in the judg-
ment, i.e. only in the relation of the object to our understand-
ing. In any knowledge which completely accords with the laws
of understanding there is no error. In a representation of the
senses -- as containing no judgment whatsoever -- there is also
no error. No natural force can of itself deviate from its own
laws. Thus neither the understanding by itself (uninfluenced
by another cause), nor the senses by themselves, would fall
into error. The former would not, since, if it acts only accord-
ing to its own laws, the effect (the judgment) must necessarily
be in conformity with these laws; conformity with the laws
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of the understanding is the formal element in all truth. In
the senses there is no judgment whatsoever, neither a true
nor a false judgment. Now since we have no source of know-
ledge besides these two, it follows that error is brought about
solely by the unobserved influence of sensibility on the under-
standing, through which it happens that the subjective grounds
of the judgment enter into union with the objective grounds
and make these latter deviate from their true function, -- just
as a body in motion would always of itself continue in a
straight line in the same direction, but if influenced by another
force acting in another direction starts off into curvilinear
motion. In order to distinguish the specific action of under-
standing from the force which is intermixed with it, it is neces-
sary to regard the erroneous judgment as the diagonal between
two forces -- forces which determine the judgment in different
directions that enclose, as it were, an angle -- and to resolve
this composite action into the simple actions of the under-
standing and of the sensibility. In the case of pure a priori
judgments this is a task which falls to be discharged by tran-
scendental reflection, through which, as we have already shown,
every representation is assigned its place in the corresponding
faculty of knowledge, and by which the influence of the one
upon the other is therefore likewise distinguished. 
We are not here concerned with empirical (e.g. optical)
illusion, which occurs in the empirical employment of rules of
understanding that are otherwise correct, and through which
the faculty of judgment is misled by the influence of imagina-
tion; we are concerned only with transcendental illusion, which
exerts its influence on principles that are in no wise intended for
use in experience, in which case we should at least have had a
criterion of their correctness. In defiance of all the warnings of
criticism, it carries us altogether beyond the empirical employ-
ment of categories and puts us off with a merely deceptive exten-
sion of pure understanding. 
++ Sensibility, when subordinated to understanding, as the object
upon which the latter exercises its function, is the source of real
modes of knowledge. But the same sensibility, in so far as it in-
fluences the operation of understanding, and determines it to make
judgments, is the ground of error. 
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We shall entitle the principles whose
application is confined entirely within the limits of possible
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experience, immanent; and those, on the other hand, which
profess to pass beyond these limits, transcendent. In the case of
these latter, I am not referring to the transcendental employ-
ment or misemployment of the categories, which is merely an
error of the faculty of judgment when it is not duly curbed by
criticism, and therefore does not pay sufficient attention to the
bounds of the territory within which alone free play is allowed
to pure understanding. I mean actual principles which incite
us to tear down all those boundary-fences and to seize posses-
sion of an entirely new domain which recognises no limits of
demarcation. Thus transcendental and transcendent are not
interchangeable terms. The principles of pure understanding,
which we have set out above, allow only of empirical and not
of transcendental employment, that is, employment extend-
ing beyond the limits of experience. A principle, on the other
hand, which takes away these limits, or even commands us
actually to transgress them, is called transcendent. If our
criticism can succeed in disclosing the illusion in these alleged
principles, then those principles which are of merely empirical
employment may be called, in opposition to the others, im-
manent principles of pure understanding. 
Logical illusion, which consists in the mere imitation
of the form of reason (the illusion of formal fallacies), arises
entirely from lack of attention to the logical rule. As soon
as attention is brought to bear on the case that is before us,
the illusion completely disappears. Transcendental illusion,
on the other hand, does not cease even after it has been de-
tected and its invalidity clearly revealed by transcendental
criticism (e.g. the illusion in the proposition: the world must
have a beginning in time). The cause of this is that there are
fundamental rules and maxims for the employment of our
reason (subjectively regarded as a faculty of human know-
ledge), and that these have all the appearance of being ob-
jective principles. We therefore take the subjective necessity
of a connection of our concepts, which is to the advantage of
the understanding, for an objective necessity in the deter-
mination of things in themselves. This is an illusion which
can no more be prevented than we can prevent the sea
appearing higher at the horizon than at the shore, since we see
it through higher light rays; or to cite a still better example,
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than the astronomer can prevent the moon from appearing
larger at its rising, although he is not deceived by this illusion. 
The transcendental dialectic will therefore content itself
with exposing the illusion of transcendent judgments, and at
the same time taking precautions that we be not deceived by
it. That the illusion should, like logical illusion, actually dis-
appear and cease to be an illusion, is something which tran-
scendental dialectic can never be in a position to achieve. For
here we have to do with a natural and inevitable illusion,
which rests on subjective principles, and foists them upon us
as objective; whereas logical dialectic in its exposure of de-
ceptive inferences has to do merely with an error in the fol-
lowing out of principles, or with an illusion artificially created
in imitation of such inferences. There exists, then, a natural
and unavoidable dialectic of pure reason -- not one in which a
bungler might entangle himself through lack of knowledge,
or one which some sophist has artificially invented to confuse
thinking people, but one inseparable from human reason, and
which, even after its deceptiveness has been exposed, will not
cease to play tricks with reason and continually entrap it into
momentary aberrations ever and again calling for correction. 
Reason in general 
All our knowledge starts with the senses, proceeds from
thence to understanding, and ends with reason, beyond which
there is no higher faculty to be found in us for elaborating the
matter of intuition and bringing it under the highest unity of
thought. Now that I have to give an explanation of this highest
faculty of knowledge, I find myself in some difficulty. Reason,
like understanding, can be employed in a merely formal, that
is, logical manner, wherein it abstracts from all content of
knowledge. But it is also capable of a real use, since it contains
within itself the source of certain concepts and principles,
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which it does not borrow either from the senses or from the
understanding. The former faculty has long since been defined
by logicians as the faculty of making mediate inferences (in dis-
tinction from immediate inferences, consequentiis immediatis);
but the nature of the other faculty, which itself gives birth to con-
cepts, is not to be understood from this definition. Now since
we are here presented with a division of reason into a logical
and a transcendental faculty, we are constrained to seek for a
higher concept of this source of knowledge which includes
both concepts as subordinate to itself. Following the analogy
of concepts of understanding, we may expect that the logical
concept will provide the key to the transcendental, and that
the table of the functions of the former will at once give us the
genealogical tree of the concepts of reason. 
In the first part of our transcendental logic we treated the
understanding as being the faculty of rules; reason we shall
here distinguish from understanding by entitling it the faculty
of principles. 
The term 'principle' is ambiguous, and commonly sig-
nifies any knowledge which can be used as a principle,
although in itself, and as regards its proper origin, it is no
principle. Every universal proposition, even one derived from
experience, through induction, can serve as major premiss in
a syllogism; but it is not therefore itself a principle. The
mathematical axioms (e.g. that there can only be one straight
line between two points) are instances of universal a priori
knowledge, and are therefore rightly called principles, rela-
tively to the cases which can be subsumed under them. But I
cannot therefore say that I apprehend this property of straight
lines in general and in itself, from principles; I apprehend it
only in pure intuition. 
Knowledge from principles is, therefore, that knowledge
alone in which I apprehend the particular in the universal
through concepts. Thus every syllogism is a mode of deducing
knowledge from a principle. For the major premiss always
gives a concept through which everything that is subsumed
under the concept as under a condition is known from the con-
cept according to a principle. Now since any universal know-
ledge can serve as major premiss in a syllogism, and since the
understanding presents us with universal a priori propositions
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of this kind, they can also be called principles in respect of
their possible employment. 
 But if we consider them in themselves in relation to their
origin, these fundamental propositions of pure understanding
are anything rather than knowledge based on concepts. For
they would not even be possible a priori, if we were not sup-
ported by pure intuition (in mathematics), or by conditions of
a possible experience in general. That everything that happens
has a cause cannot be inferred merely from the concept of
happening in general; on the contrary, it is this fundamental
proposition which shows how in regard to that which happens
we are in a position to obtain in experience any concept what-
soever that is really determinate. 
The understanding can, then, never supply any synthetic
modes of knowledge derived from concepts; and it is such
modes of knowledge that are properly, without qualification,
to be entitled 'principles'. All universal propositions, however,
may be spoken of as 'principles' in a comparative sense. 
It has long been wished -- and sometime perhaps (who
knows when! ) may be fulfilled -- that instead of the endless
multiplicity of civil laws we should be able to fall back on their
general principles. For it is in these alone that we can hope to
find the secret of what we are wont to call the simplifying of
legislation. In this domain, however, the laws are only limita-
tions imposed upon our freedom in order that such freedom
may completely harmonise with itself; hence they are directed
to something which is entirely our own work, and of which we
ourselves, through these concepts, can be the cause. But that
objects in themselves, the very nature of things, should stand
under principles, and should be determined according to mere
concepts, is a demand which, if not impossible, is at least quite
contrary to common sense. But however that may be (it is
a question which we still have to discuss), it is now at least
evident that knowledge derived from principles which are
genuinely such is something quite different from knowledge
obtained merely through the understanding. The latter may,
indeed, also take the form of a principle and thus be prior to
some other knowledge, but in itself, in so far as it is syn-
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thetic, it does not depend on thought alone, nor contain in
itself a universal obtained from concepts. 
Understanding may be regarded as a faculty which secures
the unity of appearances by means of rules, and reason as
being the faculty which secures the unity of the rules of under-
standing under principles. Accordingly, reason never applies
itself directly to experience or to any object, but to understand-
ing, in order to give to the manifold knowledge of the latter
an a priori unity by means of concepts, a unity which may be
called the unity of reason, and which is quite different in kind
from any unity that can be accomplished by the understanding. 
This is the universal concept of the faculty of reason in so
far as it has been possible to make it clear in the total absence
of examples. These will be given in the course of our argu-
The Logical Employment of Reason 
A distinction is commonly made between what is immediately
known and what is merely inferred. That in a figure which is
bounded by three straight lines there are three angles, is known
immediately; but that the sum of these angles is equal to two right
angles, is merely inferred. Since we have constantly to make
use of inference, and so end by becoming completely accus-
tomed to it, we no longer take notice of this distinction, and
frequently, as in the so-called deceptions of the senses, treat as
being immediately perceived what has really only been inferred. 
In every process of reasoning there is a fundamental proposi-
tion, and another, namely the conclusion, which is drawn
from it, and finally, the inference (logical sequence) by which
the truth of the latter is inseparably connected with the truth
of the former. If the inferred judgment is already so contained
in the earlier judgment that it may be derived from it without
the mediation of a third representation, the inference is called
immediate (consequentia immediata) -- I should prefer to entitle
it inference of the understanding. But if besides the know-
ledge contained in the primary proposition still another judg-
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ment is needed to yield the conclusion, it is to be entitled an
inference of the reason. In the proposition : "All men are
mortal", there are already contained the propositions : "some
men are mortal", "some mortal beings are men", "nothing
that is not mortal is a man"; and these are therefore immediate
conclusions from it. On the other hand, the proposition: "All
learned beings are mortal", is not contained in the funda-
mental judgment (for the concept of learned beings does not
occur in it at all), and it can only be inferred from it by means
of a mediating judgment. 
In every syllogism I first think a rule (the major premiss)
through the understanding. Secondly, I subsume something
known under the condition of the rule by means of judgment
(the minor premiss). Finally, what is thereby known I deter-
mine through the predicate of the rule, and so a priori through
reason (the conclusion). The relation, therefore, which the
major premiss, as the rule, represents between what is known
and its condition is the ground of the different kinds of syllo-
gism. Consequently, syllogisms, like judgments, are of three
kinds, according to the different ways in which, in the under-
standing, they express the relation of what is known; they
are either categorical, hypothetical, or disjunctive. 
If, as generally happens, the judgment that forms the con-
clusion is set as a problem -- to see whether it does not follow
from judgments already given, and through which a quite
different object is thought -- I look in the understanding for the
assertion of this conclusion, to discover whether it is not there
found to stand under certain conditions according to a uni-
versal rule. If I find such a condition, and if the object of the
conclusion can be subsumed under the given condition, then
the conclusion is deduced from the rule, which is also valid for
other objects of knowledge. From this we see that in inference
reason endeavours to reduce the varied and manifold know-
ledge obtained through the understanding to the smallest
number of principles (universal conditions) and thereby to
achieve in it the highest possible unity. 
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The Pure Employment of Reason 
Can we isolate reason, and is it, so regarded, an independ-
ent source of concepts and judgments which spring from it
alone, and by means of which it relates to objects; or is it a
merely subordinate faculty, for imposing on given modes of
knowledge a certain form, called logical -- a faculty through
which what is known by means of the understanding is deter-
mined in its interrelations, lower rules being brought under
higher (namely, those the condition of which includes in its
own sphere the condition of the lower), as far as this can be
done through [processes of] comparison? This is the question
with which we are now provisionally occupying ourselves. As
a matter of fact, multiplicity of rules and unity of principles is a
demand of reason, for the purpose of bringing the understand-
ing into thoroughgoing accordance with itself, just as the
understanding brings the manifold of intuition under concepts
and thereby connects the manifold. But such a principle does
not prescribe any law for objects, and does not contain any
general ground of the possibility of knowing or of determining
objects as such; it is merely a subjective law for the orderly
management of the possessions of our understanding, that by
comparison of its concepts it may reduce them to the smallest
possible number; it does not justify us in demanding from the
objects such uniformity as will minister to the convenience
and extension of our understanding; and we may not, there-
fore, ascribe to the maxim any objective validity. In a word,
the question is, does reason in itself, that is, does pure reason,
contain a priori synthetic principles and rules, and in what
may these principles consist? 
The formal and logical procedure of reason in syllogisms
gives us sufficient guidance as to the ground on which the
transcendental principle of pure reason in its synthetic know-
ledge will rest. 
In the first place, reason in the syllogism does not concern
itself with intuitions, with a view to bringing them under rules
(as the understanding does with its categories), but with con-
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cepts and judgments. Accordingly, even if pure reason does
concern itself with objects, it has no immediate relation to
these and the intuition of them, but only to the understand-
ing and its judgments -- which deal at first hand with the senses
and their intuition for the purpose of determining their object. 
The unity of reason is therefore not the unity of a possible
experience, but is essentially different from such unity, which
is that of understanding. That everything which happens has
a cause, is not a principle known and prescribed by reason. 
That principle makes the unity of experience possible, and
borrows nothing from reason, which, apart from this relation
to possible experience, could never, from mere concepts, have
imposed any such synthetic unity. 
Secondly, reason, in its logical employment, seeks to dis-
cover the universal condition of its judgment (the conclusion),
and the syllogism is itself nothing but a judgment made by
means of the subsumption of its condition under a universal
rule (the major premiss). Now since this rule is itself subject
to the same requirement of reason, and the condition of the con-
dition must therefore be sought (by means of a prosyllogism)
whenever practicable, obviously the principle peculiar to reason
in general, in its logical employment, is: -- to find for the con-
ditioned knowledge obtained through the understanding the
unconditioned whereby its unity is brought to completion. 
But this logical maxim can only become a principle of
pure reason through our assuming that if the conditioned is
given, the whole series of conditions, subordinated to one
another -- a series which is therefore itself unconditioned --
is likewise given, that is, is contained in the object and its
Such a principle of pure reason is obviously synthetic;
the conditioned is analytically related to some condition but
not to the unconditioned. From the principle there must also
follow various synthetic propositions, of which pure under-
standing -- inasmuch as it has to deal only with objects of a
possible experience, the knowledge and synthesis of which is
always conditioned -- knows nothing. The unconditioned, if its
actuality be granted, is especially to be considered in respect
of all the determinations which distinguish it from whatever
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is conditioned, and thereby must yield material for many
synthetic a priori propositions. 
The principles arising from this supreme principle of
pure reason will, however, be transcendent in relation to all
appearances, i.e. there can never be any adequate empirical
employment of the principle. It will therefore be entirely
different from all principles of understanding, the employment
of which is wholly immanent, inasmuch as they have as their
theme only the possibility of experience. Take the principle,
that the series of conditions (whether in the synthesis of
appearances, or even in the thinking of things in general)
extends to the unconditioned. Does it, or does it not, have
objective applicability? What are its implications as regards
the empirical employment of understanding? Or is there
no such objectively valid principle of reason, but only
a logical precept, to advance towards completeness by an
ascent to ever higher conditions and so to give to our know-
ledge the greatest possible unity of reason? Can it be that
this requirement of reason has been wrongly treated in being
viewed as a transcendental principle of pure reason, and that
we have been overhasty in postulating such an unbounded
completeness of the series of conditions in the objects them-
selves? In that case, what other misunderstandings and de-
lusions may have crept into the syllogisms, whose major pre-
miss (perhaps rather an assumption than a postulate) is
derived from pure reason, and which proceed from experience
upwards to its conditions? To answer these questions will be
our task in the Transcendental Dialectic, which we shall now
endeavour to develop from its deeply concealed sources in
human reason. We shall divide the Dialectic into two chapters,
the first on the transcendent concepts of pure reason, the
second on its transcendent and dialectical syllogisms. 
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WHATEVER we may have to decide as to the possibility of
the concepts derived from pure reason, it is at least true that
they are not to be obtained by mere reflection but only by
inference. Concepts of understanding are also thought a -
priori antecedently to experience and for the sake of experi-
ence, but they contain nothing more than the unity of reflec-
tion upon appearances, in so far as these appearances must
necessarily belong to a possible empirical consciousness. 
Through them alone is knowledge and the determination of
an object possible. They first provide the material required
for making inferences, and they are not preceded by any
a priori concepts of objects from which they could be inferred. 
On the other hand, their objective reality is founded solely
on the fact that, since they constitute the intellectual form of
all experience, it must always be possible to show their appli-
cation in experience. 
The title 'concept of reason' already gives a preliminary
indication that we are dealing with something which does
not allow of being confined within experience, since it con-
cerns a knowledge of which any empirical knowledge (perhaps
even the whole of possible experience or of its empirical syn-
thesis) is only a part. No actual experience has ever been com-
pletely adequate to it, yet to it every actual experience belongs. 
Concepts of reason enable us to conceive, concepts of under-
standing to understand -- ([as employed in reference to] percep-
tions). If the concepts of reason contain the unconditioned, they
are concerned with something to which all experience is subor-
P 309
dinate, but which is never itself an object of experience --
something to which reason leads in its inferences from experi-
ence, and in accordance with which it estimates and gauges
the degree of its empirical employment, but which is never
itself a member of the empirical synthesis. If, none the less,
these concepts possess objective validity, they may be called
conceptus ratiocinati (rightly inferred concepts); if, however,
they have no such validity, they have surreptitiously obtained
recognition through having at least an illusory appearance
of being inferences, and may be called conceptus ratiocinantes
(pseudo-rational concepts). But since this can be established
only in the chapter on the dialectical inferences of pure reason,
we are not yet in a position to deal with it. Meantime, just as
we have entitled the pure concepts of understanding cate-
gories, so we shall give a new name to the concepts of pure
reason, calling them transcendental ideas. This title we shall
now explain and justify. 
Section I
Despite the great wealth of our languages, the thinker often
finds himself at a loss for the expression which exactly fits his
concept, and for want of which he is unable to be really intel-
ligible to others or even to himself. To coin new words is to ad-
vance a claim to legislation in language that seldom succeeds;
and before we have recourse to this desperate expedient it is
advisable to look about in a dead and learned language, to see
whether the concept and its appropriate expression are not
already there provided. Even if the old-time usage of a term
should have become somewhat uncertain through the careless-
ness of those who introduced it, it is always better to hold fast
to the meaning which distinctively belongs to it (even though
it remain doubtful whether it was originally used in precisely
this sense) than to defeat our purpose by making ourselves
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For this reason, if there be only a single word the estab-
lished meaning of which exactly agrees with a certain concept,
then, since it is of great importance that this concept be dis-
tinguished from related concepts, it is advisable to economise
in the use of the word and not to employ it, merely for the sake of
variety, as a synonym for some other expression, but carefully
to keep to its own proper meaning. Otherwise it may easily
happen that the expression ceasing to engage the attention in
one specific sense, and being lost in the multitude of other
words of very different meaning, the thought also is lost which
it alone could have preserved. 
 Plato made use of the expression 'idea' in such a way as
quite evidently to have meant by it something which not only can
never be borrowed from the senses but far surpasses even the
concepts of understanding (with which Aristotle occupied him-
self), inasmuch as in experience nothing is ever to be met with
that is coincident with it. For Plato ideas are archetypes
of the things themselves, and not, in the manner of the cate-
gories, merely keys to possible experiences. In his view they
have issued from highest reason, and from that source have
come to be shared in by human reason, which, however, is now
no longer in its original state, but is constrained laboriously to
recall, by a process of reminiscence (which is named philo-
sophy), the old ideas, now very much obscured. I shall not
engage here in any literary enquiry into the meaning which
this illustrious philosopher attached to the expression. I need
only remark that it is by no means unusual, upon comparing
the thoughts which an author has expressed in regard to his
subject, whether in ordinary conversation or in writing, to find
that we understand him better than he has understood himself. 
As he has not sufficiently determined his concept, he has some-
times spoken, or even thought, in opposition to his own in-
Plato very well realised that our faculty of knowledge feels
a much higher need than merely to spell out appearances ac-
cording to a synthetic unity, in order to be able to read them
as experience. He knew that our reason naturally exalts itself
to forms of knowledge which so far transcend the bounds of
experience that no given empirical object can ever coincide
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with them, but which must none the less be recognised as
having their own reality, and which are by no means mere
fictions of the brain. 
Plato found the chief instances of his ideas in the field of
the practical, that is, in what rests upon freedom, which in its
turn rests upon modes of knowledge that are a peculiar product
of reason. Whoever would derive the concepts of virtue from
experience and make (as many have actually done) what at best
can only serve as an example in an imperfect kind of exposi-
tion, into a pattern from which to derive knowledge, would
make of virtue something which changes according to time
and circumstance, an ambiguous monstrosity not admitting of
the formation of any rule. On the contrary, as we are well
aware, if anyone is held up as a pattern of virtue, the true
original with which we compare the alleged pattern and by
which alone we judge of its value is to be found only in our
minds. This original is the idea of virtue, in respect of which
the possible objects of experience may serve as examples
(proofs that what the concept of reason commands is in a cer-
tain degree practicable), but not as archetype. That no one
of us will ever act in a way which is adequate to what is con-
tained in the pure idea of virtue is far from proving this thought
to be in any respect chimerical. For it is only by means of this
idea that any judgment as to moral worth or its opposite is
possible; and it therefore serves as an indispensable founda-
tion for every approach to moral perfection -- however the
obstacles in human nature, to the degree of which there are no
assignable limits, may keep us far removed from its complete
++ He also, indeed, extended his concept so as to cover specu-
lative knowledge, provided only the latter was pure and given com-
pletely a priori. He even extended it to mathematics, although the
object of that science is to be found nowhere except in possible ex-
perience. In this I cannot follow him, any more than in his mystical
deduction of these ideas, or in the extravagances whereby he, so to
speak, hypostatised them -- although, as must be allowed, the exalted
language, which he employed in this sphere, is quite capable of a
milder interpretation that accords with the nature of things. 
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The Republic of Plato has become proverbial as a striking
example of a supposedly visionary perfection, such as can exist
P 312
only in the brain of the idle thinker; and Brucker has ridiculed
the philosopher for asserting that a prince can rule well only
in so far as he participates in the ideas. We should, however,
be better advised to follow up this thought, and, where the
great philosopher leaves us without help, to place it, through
fresh efforts, in a proper light, rather than to set it aside as use-
less on the very sorry and harmful pretext of impracticability. 
A constitution allowing the greatest possible human freedom in
accordance with laws by which the freedom of each is made to
be consistent with that of all others -- I do not speak of the
greatest happiness, for this will follow of itself -- is at any rate
a necessary idea, which must be taken as fundamental not only
in first projecting a constitution but in all its laws. For at the
start we are required to abstract from the actually existing
hindrances, which, it may be, do not arise unavoidably out
of human nature, but rather are due to a quite remediable
cause, the neglect of the pure ideas in the making of the laws. 
Nothing, indeed, can be more injurious, or more unworthy of
a philosopher, than the vulgar appeal to so-called adverse ex-
perience. Such experience would never have existed at all, if
at the proper time those institutions had been established in
accordance with ideas, and if ideas had not been displaced by
crude conceptions which, just because they have been derived
from experience, have nullified all good intentions. The more
legislation and government are brought into harmony with the
above idea, the rarer would punishments become, and it is there-
fore quite rational to maintain, as Plato does, that in a perfect
state no punishments whatsoever would be required. This per-
fect state may never, indeed, come into being; none the less
this does not affect the rightfulness of the idea, which, in order
to bring the legal organisation of mankind ever nearer to its
greatest possible perfection, advances this maximum as an
archetype. For what the highest degree may be at which
mankind may have to come to a stand, and how great a gulf
may still have to be left between the idea and its realisation,
are questions which no one can, or ought to, answer. For the
issue depends on freedom; and it is in the power of freedom
to pass beyond any and every specified limit. 
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But it is not only where human reason exhibits genuine
causality, and where ideas are operative causes (of actions and
their objects), namely, in the moral sphere, but also in regard
to nature itself, that Plato rightly discerns clear proofs of an
origin from ideas. A plant, an animal, the orderly arrangement
of the cosmos -- presumably therefore the entire natural world
-- clearly show that they are possible only according to ideas,
and that though no single creature in the conditions of its
individual existence coincides with the idea of what is most
perfect in its kind -- just as little as does any human being
with the idea of humanity, which he yet carries in his soul
as the archetype of his actions -- these ideas are none the
less completely determined in the Supreme Understanding,
each as an individual and each as unchangeable, and are
the original causes of things. But only the totality of things,
in their interconnection as constituting the universe, is com-
pletely adequate to the idea. If we set aside the exaggera-
tions in Plato's methods of expression, the philosopher's
spiritual flight from the ectypal mode of reflecting upon the
physical world-order to the architectonic ordering of it ac-
cording to ends, that is, according to ideas, is an enterprise
which calls for respect and imitation. It is, however, in regard
to the principles of morality, legislation, and religion, where
the experience, in this case of the good, is itself made possible
only by the ideas -- incomplete as their empirical expression
must always remain -- that Plato's teaching exhibits its quite
peculiar merits. When it fails to obtain recognition, this is due
to its having been judged in accordance with precisely those
empirical rules, the invalidity of which, regarded as principles,
it has itself demonstrated. For whereas, so far as nature is con-
cerned, experience supplies the rules and is the source of
truth, in respect of the moral laws it is, alas, the mother of
illusion! Nothing is more reprehensible than to derive the laws
prescribing what ought to be done from what is done, or to
impose upon them the limits by which the latter is circum-
But though the following out of these considerations is
what gives to philosophy its peculiar dignity, we must mean-
time occupy ourselves with a less resplendent, but still meri-
P 314
torious task, namely, to level the ground, and to render it
sufficiently secure for moral edifices of these majestic dimen-
sions. For this ground has been honeycombed by subterranean
workings which reason, in its confident but fruitless search
for hidden treasures, has carried out in all directions, and
which threaten the security of the superstructures. Our present
duty is to obtain insight into the transcendental employment
of pure reason, its principles and ideas, that we may be in a
position to determine and estimate its influence and true value. 
Yet, before closing these introductory remarks, I beseech
those who have the interests of philosophy at heart (which is
more than is the case with most people) that, if they find
themselves convinced by these and the following considera-
tions, they be careful to preserve the expression 'idea' in
its original meaning, that it may not become one of those
expressions which are commonly used to indicate any and
every species of representation, in a happy-go-lucky confu-
sion, to the consequent detriment of science. There is no lack
of terms suitable for each kind of representation, that we
should thus needlessly encroach upon the province of any one
of them. Their serial arrangement is as follows. The genus
is representation in general (repraesentatio). Subordinate to
it stands representation with consciousness (perceptio). A
perception which relates solely to the subject as the modifica-
tion of its state is sensation (sensatio), an objective perception
is knowledge (cognitio). This is either intuition or concept
(intuitus vel conceptus). The former relates immediately to the
object and is single, the latter refers to it immediately by means
of a feature which several things may have in common. The
concept is either an empirical or a pure concept. The pure con-
cept, in so far as it has its origin in the understanding alone
(not in the pure image of sensibility), is called a notion. A
concept formed from notions and transcending the possibility
of experience is an idea or concept of reason. Anyone who
has familiarised himself with these distinctions must find it
intolerable to hear the representation of the colour, red, called
an idea. It ought not even to be called a concept of under-
standing, a notion. 
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Section 2
The Transcendental Analytic has shown us how the mere
logical form of our knowledge may in itself contain original
pure a priori concepts, which represent objects prior to all
experience, or, speaking more correctly, indicate the synthetic
unity which alone makes possible an empirical knowledge of
objects. The form of judgments (converted into a concept of
the synthesis of intuitions) yielded categories which direct all
employment of understanding in experience. Similarly, we
may presume that the form of syllogisms, when applied to
the synthetic unity of intuitions under the direction of the
categories, will contain the origin of special a priori concepts,
which we may call pure concepts of reason, or transcendental
ideas, and which will determine according to principles how
understanding is to be employed in dealing with experience
in its totality. 
The function of reason in its inferences consists in the
universality of knowledge [which it yields] according to con-
cepts, the syllogism being itself a judgment which is deter-
mined a priori in the whole extent of its conditions. The pro-
position, 'Caius is mortal', I could indeed derive from experi-
ence by means of the understanding alone. But I am in pursuit
of a concept (in this case, the concept 'man') that contains the
condition under which the predicate (general term for what
is asserted) of this judgment is given; and after I have sub-
sumed the predicate under this condition taken in its whole
extension ('All men are mortal'), I proceed, in accordance
therewith, to determine the knowledge of my object ('Caius
is mortal'). 
Accordingly, in the conclusion of a syllogism we restrict a
P 316
predicate to a certain object, after having first thought it in
the major premiss in its whole extension under a given con-
dition. This complete quantity of the extension in relation to
such a condition is called universality (universalitas). In the
synthesis of intuitions we have corresponding to this the allness
(universitas) or totality of the conditions. The transcendental
concept of reason is, therefore, none other than the concept of
the totality of the conditions for any given conditioned. Now
since it is the unconditioned alone which makes possible the
totality of conditions, and, conversely, the totality of conditions
is always itself unconditioned, a pure concept of reason can
in general be explained by the concept of the unconditioned,
conceived as containing a ground of the synthesis of the
 The number of pure concepts of reason will be equal to the
number of kinds of relation which the understanding repre-
sents to itself by means of the categories. We have therefore
to seek for an unconditioned, first, of the categorical synthesis
in a subject; secondly, of the hypothetical synthesis of the
members of a series; thirdly, of the disjunctive synthesis of the
parts in a system. 
There is thus precisely the same number of kinds of syl-
logism, each of which advances through prosyllogisms to the
unconditioned: first, to the subject which is never itself a pre-
dicate; secondly, to the presupposition which itself presup-
poses nothing further; thirdly, to such an aggregate of the
members of the division of a concept as requires nothing
further to complete the division. The pure concepts of reason
-- of totality in the synthesis of conditions -- are thus at least
necessary as setting us the task of extending the unity of
understanding, where possible, up to the unconditioned, and
are grounded in the nature of human reason. These tran-
scendental concepts may, however, be without any suitable
corresponding employment in concreto, and may therefore
have no other utility than that of so directing the understand-
ing that, while it is extended to the uttermost, it is also at the
same time brought into complete consistency with itself. 
 But while we are here speaking of the totality of con-
ditions and of the unconditioned, as being equivalent titles
for all concepts of reason, we again come upon an expression
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with which we cannot dispense, and which yet, owing to an
ambiguity that attaches to it through long-standing misuse,
we also cannot with safety employ. The word 'absolute' is
one of the few words which in their original meaning were
adapted to a concept that no other word in the same language
exactly suits. Consequently its loss, or what amounts to the
same thing, looseness in its employment, must carry with it
the loss of the concept itself. And since, in this case, the con-
cept is one to which reason devotes much of its attention,
it cannot be relinquished without greatly harming all tran-
scendental philosophy. The word 'absolute' is now often used
merely to indicate that something is true of a thing considered
in itself, and therefore of its inward nature. In this sense the
absolutely possible would mean that which in itself (interne)
is possible -- which is, in fact, the least that can be said of an
object. On the other hand, the word is also sometimes used to
indicate that something is valid in all respects, without limita-
tion, e.g. absolute despotism, and in this sense the absolutely
possible would mean what is in every relation (in all respects)
possible -- which is the most that can be said of the possibility
of a thing. Now frequently we find these two meanings com-
bined. For example, what is internally impossible is impossible
in any relation, and therefore absolutely impossible. But in
most cases the two meanings are infinitely far apart, and I can
in no wise conclude that because something is in itself possible,
it is therefore also possible in every relation, and so absolutely
possible. Indeed, as I shall subsequently show, absolute neces-
sity is by no means always dependent on inner necessity, and
must not, therefore, be treated as synonymous with it. If the
opposite of something is internally impossible, this opposite
is, of course, impossible in all respects, and the thing itself
is therefore absolutely necessary. But I cannot reverse the
reasoning so as to conclude that if something is absolutely
necessary its opposite is internally impossible, i.e. that the
absolute necessity of things is an inner necessity. For this
inner necessity is in certain cases a quite empty expression
to which we cannot attach any concept whatsoever, whereas
the concept of the necessity of a thing in all relations (to every-
thing possible) involves certain quite special determinations. 
P 318
Since the loss of a concept that is of great importance for
speculative science can never be a matter of indifference to the
philosopher, I trust that the fixing and careful preservation
of the expression, on which the concept depends, will like-
wise be not indifferent to him. 
 It is, then, in this wider sense that I shall use the word
'absolute', opposing it to what is valid only comparatively,
that is, in some particular respect. For while the latter is re-
stricted by conditions, the former is valid without restriction. 
Now the transcendental concept of reason is directed
always solely towards absolute totality in the synthesis of con-
ditions, and never terminates save in what is absolutely, that is,
in all relations, unconditioned. For pure reason leaves every-
thing to the understanding -- the understanding [alone] apply-
ing immediately to the objects of intuition, or rather to their
synthesis in the imagination. Reason concerns itself exclusively
with absolute totality in the employment of the concepts of the
understanding, and endeavours to carry the synthetic unity. 
which is thought in the category, up to the completely uncon-
ditioned. We may call this unity of appearances the unity of
reason, and that expressed by the category the unity of under-
standing. Reason accordingly occupies itself solely with the
employment of understanding, not indeed in so far as the latter
contains the ground of possible experience (for the concept of
the absolute totality of conditions is not applicable in any
experience, since no experience is unconditioned), but solely
in order to prescribe to the understanding its direction to-
wards a certain unity of which it has itself no concept, and
in such manner as to unite all the acts of the understanding,
in respect of every object, into an absolute whole. The object-
ive employment of the pure concepts of reason is, therefore,
always transcendent, while that of the pure concepts of under-
standing must, in accordance with their nature, and inasmuch
as their application is solely to possible experience, be always
I understand by idea a necessary concept of reason to
which no corresponding object can be given in sense-ex-
perience. Thus the pure concepts of reason, now under con-
sideration, are transcendental ideas. They are concepts of pure
P 319
reason, in that they view all knowledge gained in experience as
being determined through an absolute totality of conditions. 
They are not arbitrarily invented; they are imposed by the
very nature of reason itself, and therefore stand in necessary
relation to the whole employment of understanding. Finally,
they are transcendent and overstep the limits of all experi-
ence; no object adequate to the transcendental idea can ever be
found within experience. If I speak of an idea, then as regards
its object, viewed as an object of pure understanding, I am
saying a great deal, but as regards its relation to the subject,
that is, in respect of its actuality under empirical conditions,
I am for the same reason saying very little, in that, as being
the concept of a maximum, it can never be correspondingly
given in concreto. Since in the merely speculative employment
of reason the latter [namely, to determine the actuality of the
idea under empirical conditions] is indeed our whole purpose,
and since the approximation to a concept, which yet is never
actually reached, puts us in no better position than if the con-
cept were entirely abortive, we say of such a concept -- it is only
an idea. The absolute whole of all appearances -- we might thus
say -- is only an idea; since we can never represent it in image,
it remains a problem to which there is no solution. But since,
on the other hand, in the practical employment of understand-
ing, our sole concern is with the carrying out of rules, the idea
of practical reason can always be given actually in concreto,
although only in part; it is, indeed, the indispensable condition
of all practical employment of reason. The practice of it is al-
ways limited and defective, but is not confined within determin-
able boundaries, and is therefore always under the influence
of the concept of an absolute completeness. The practical idea
is, therefore, always in the highest degree fruitful, and in its
relation to our actual activities is indispensably necessary. 
Reason is here, indeed, exercising causality, as actually
bringing about that which its concept contains; and of such
wisdom we cannot, therefore, say disparagingly it is only an
idea. On the contrary, just because it is the idea of the neces-
sary unity of all possible ends, it must as an original, and at
least restrictive condition, serve as standard in all that bears
on the practical. 
Although we must say of the transcendental concepts of
P 320
reason that they are only ideas, this is not by any means to be
taken as signifying that they are superfluous and void. For
even if they cannot determine any object, they may yet, in a
fundamental and unobserved fashion, be of service to the
understanding as a canon for its extended and consistent em-
ployment. The understanding does not thereby obtain more
knowledge of any object than it would have by means of its
own concepts, but for the acquiring of such knowledge it
receives better and more extensive guidance. Further -- what
we need here no more than mention -- concepts of reason may
perhaps make possible a transition from the concepts of
nature to the practical concepts, and in that way may give
support to the moral ideas themselves, bringing them into
connection with the speculative knowledge of reason. As to
all this, we must await explanation in the sequel. 
In accordance with our plan we leave aside the practical
ideas, and consider reason only in its speculative, or rather,
restricting ourselves still further, only in its transcendental
employment. Here we must follow the path that we have
taken in the deduction of the categories; we must consider
the logical form of knowledge through reason, to see whether
perhaps reason may not thereby be likewise a source of con-
cepts which enable us to regard objects in themselves as deter-
mined synthetically a priori, in relation to one or other of the
functions of reason. 
 Reason, considered as the faculty of a certain logical form
of knowledge, is the faculty of inferring, i.e. judging medi-
ately (by the subsumption of the condition of a possible judg-
ment under the condition of a given judgment). The given
judgment is the universal rule (major premiss). The subsump-
tion of the condition of another possible judgment under the
condition of the rule is the minor premiss. The actual judg-
ment which applies the assertion of the rule to the subsumed
case is the conclusion. The rule states something universally,
subject to a certain condition. The condition of the rule is
found to be fulfilled in an actual case. What has been asserted
to be universally valid under that condition is therefore to be
regarded as valid also in the actual case, which involves that
condition. It is very evident, therefore, that reason arrives at
P 321
knowledge by means of acts of the understanding which con-
stitute a series of conditions. Thus if I arrive at the proposi-
tion that all bodies are alterable, only by beginning with
the more remote knowledge (in which the concept of body
does not occur, but which nevertheless contains the condi-
tion of that concept), namely, that everything composite is
alterable; if I then proceed from this to a proposition which
is less remote and stands under the condition of the last-
named proposition, namely, that bodies are composite; and if
from this I finally pass to a third proposition, which connects
the more remote knowledge (alterable) with the knowledge
actually before me, and so conclude that bodies are alter-
able -- by this procedure I have arrived at knowledge (a con-
clusion) by means of a series of conditions (the premisses). 
Now every series the exponent of which is given (in categori-
cal or hypothetical judgment) can be continued; consequently
this same activity of reason leads to ratiocinatio polysyllo-
gistica, which is a series of inferences that can be prolonged
indefinitely on the side either of the conditions (per prosyllo-
gismos) or of the conditioned (per episyllogismos). 
But we soon become aware that the chain or series of pro-
syllogisms, that is, of inferred knowledge on the side of the
grounds or conditions of a given knowledge, in other words, of
the ascending series of syllogisms, must stand in a different
relation to the faculty of reason from that of the descending
series, that is, of the advance of reason in the direction of the
conditioned, by means of episyllogisms. For since in the former
case the knowledge (conclusio) is given only as conditioned, we
cannot arrive at it by means of reason otherwise than on the
assumption that all the members of the series on the side of the
conditions are given (totality in the series of the premisses);
only on this assumption is the judgment before us possible
a priori: whereas on the side of the conditioned, in respect of
consequences, we only think a series in process of becoming,
not one already presupposed or given in its completeness, and
therefore an advance that is merely potential. If, therefore,
knowledge be viewed as conditioned, reason is constrained to
regard the series of conditions in the ascending line as com-
pleted and as given in their totality. But if the same knowledge
P 322
is viewed as a condition of yet other knowledge, and this know-
ledge as constituting a series of consequences in a descend-
ing line, reason can be quite indifferent as to how far this
advance extends a parte posteriori, and whether a totality of
the series is possible at all. For it does not need such a series
in order to be able to draw its conclusion, this being already
sufficiently determined and secured by its grounds a parte -
priori. The series of premisses on the side of the conditions
may have a first member, as its highest condition, or it may
have no such member, in which case it is without limits a parte -
priori. But however this may be, and even admitting that we
can never succeed in comprehending a totality of conditions,
the series must none the less contain such a totality; and the
entire series must be unconditionally true if the conditioned,
which is regarded as a consequence resulting from it, is to be
counted as true. This is a requirement of reason, which an-
nounces its knowledge as being determined a priori and as
necessary, either in itself, in which case it needs no grounds,
or, if it be derivative, as a member of a series of grounds,
which itself, as a series, is unconditionally true. 
Section 3
We are not at present concerned with logical dialectic,
which abstracts from all the content of knowledge and con-
fines itself to exposing the fallacies concealed in the form of
syllogisms, but with a transcendental dialectic which has to
contain, completely a priori, the origin of certain modes of
knowledge derived from pure reason as well as of certain
inferred concepts, the object of which can never be given em-
pirically and which therefore lie entirely outside [the sphere
of ] the faculty of pure understanding. From the natural rela-
tion which the transcendental employment of our knowledge,
alike in inferences and in judgments, must bear to its logical
P 323
employment, we have gathered that there can be only three
kinds of dialectical inference, corresponding to the three
kinds of inference through which reason can arrive at know-
ledge by means of principles, and that in all of these its busi-
ness is to ascend from the conditioned synthesis, to which
understanding always remains restricted, to the unconditioned,
which understanding can never reach. 
The relations which are to be universally found in all our
representations are (1) relation to the subject; (2) relation to
objects, either as appearances or as objects of thought in
general. If we combine the subdivision with the main division,
all relation of representations, of which we can form either a
concept or an idea, is then threefold: (1) the relation to the
subject; (2) the relation to the manifold of the object in the
[field of] appearance; (3) the relation to all things in general. 
Now all pure concepts in general are concerned with the
synthetic unity of representations, but [those of them which
are] concepts of pure reason (transcendental ideas) are con-
cerned with the unconditioned synthetic unity of all conditions
in general. All transcendental ideas can therefore be arranged in
three classes, the first containing the absolute (unconditioned)
unity of the thinking subject, the second the absolute unity of
the series of conditions of appearance, the third the absolute
unity of the condition of all objects of thought in general. 
The thinking subject is the object of psychology, the sum-
total of all appearances (the world) is the object of cosmology,
and the thing which contains the highest condition of the
possibility of all that can be thought (the being of all beings)
the object of theology. Pure reason thus furnishes the idea
for a transcendental doctrine of the soul (psychologia ratio-
nalis), for a transcendental science of the world (cosmologia
rationalis), and, finally, for a transcendental knowledge of
God (theologia transzendentalis). The understanding is not in
a position to yield even the mere project of any one of these
sciences, not even though it be supported by the highest
logical employment of reason, that is, by all the conceiv-
able inferences through which we seek to advance from one
of its objects (appearance) to all others, up to the most remote
P 324
members of the empirical synthesis; each of these sciences is
an altogether pure and genuine product, or problem, of pure
In what precise modes the pure concepts of reason come
under these three headings of all transcendental ideas will be
fully explained in the next chapter. They follow the guiding-
thread of the categories. For pure reason never relates directly
to objects, but to the concepts which understanding frames
in regard to objects. Similarly it is only by the process of
completing our argument that it can be shown how reason,
simply by the synthetic employment of that very function of
which it makes use in categorical syllogisms, is necessarily
brought to the concept of the absolute unity of the thinking
subject, how the logical procedure used in hypothetical syllo-
gisms leads to the ideal of the completely unconditioned in a
series of given conditions, and finally how the mere form of
the disjunctive syllogism must necessarily involve the highest
concept of reason, that of a being of all beings -- a thought
which, at first sight, seems utterly paradoxical. 
No objective deduction, such as we have been able to give
of the categories, is, strictly speaking, possible in the case of
these transcendental ideas. Just because they are only ideas
they have, in fact, no relation to any object that could be given
as coinciding with them. We can, indeed, undertake a sub-
jective derivation of them from the nature of our reason; and
this has been provided in the present chapter. 
As is easily seen, what pure reason alone has in view is
the absolute totality of the synthesis on the side of the con-
ditions (whether of inherence, of dependence, or of concur-
rence); it is not concerned with absolute completeness on the
side of the conditioned. For the former alone is required in
order to presuppose the whole series of the conditions, and
to present it a priori to the understanding. Once we are given
a complete (and unconditioned) condition, no concept of
reason is required for the continuation of the series; for every
step in the forward direction from the condition to the con-
ditioned is carried through by the understanding itself. The
P 325
transcendental ideas thus serve only for ascending, in the
series of conditions, to the unconditioned, that is, to principles. 
As regards the descending to the conditioned, reason does,
indeed, make a very extensive logical employment of the
laws of understanding, but no kind of transcendental employ-
ment; and if we form an idea of the absolute totality of such
a synthesis (of the progressus), as, for instance, of the whole
series of all future alterations in the world, this is a creation of
the mind (ens rationis) which is only arbitrarily thought, and
not a necessary presupposition of reason. For the possibility
of the conditioned presupposes the totality of its conditions,
but not of its consequences. Such a concept is not, therefore,
one of the transcendental ideas; and it is with these alone that
we have here to deal. 
Finally, we also discern that a certain connection and
unity is evident among the transcendental ideas themselves,
and that by means of them pure reason combines all its
modes of knowledge into a system. The advance from the
knowledge of oneself (the soul) to the knowledge of the world,
and by means of this to the original being, is so natural that it
seems to resemble the logical advance of reason from premisses
to conclusion. 
++ Metaphysics has as the proper ob-
ject of its enquiries three ideas only: God, freedom, and immortality
-- so related that the second concept, when combined with the first,
should lead to the third as a necessary conclusion. Any other matters
with which this science may deal serve merely as a means of arriving
at these ideas and of establishing their reality. It does not need the
ideas for the purposes of natural science, but in order to pass beyond
nature. Insight into them would render theology and morals, and,
through the union of these two, likewise religion, and therewith the
highest ends of our existence, entirely and exclusively dependent on
the faculty of speculative reason. In a systematic representation of
the ideas, the order cited, the synthetic, would be the most suitable;
but in the investigation which must necessarily precede it the
analytic, or reverse order, is better adapted to the purpose of com-
pleting our great project, as enabling us to start from what is im-
mediately given us in experience -- advancing from the doctrine of
the soul, to the doctrine of the world, and thence to the knowledge
of God. 
P 325
Whether this is due to a concealed relationship
of the same kind as subsists between the logical and the trans-
cendental procedure, is one of the questions that await answer
P 326
in the course of these enquiries. Indeed, we have already,
in a preliminary manner, obtained an answer to the question,
since in treating of the transcendental concepts of reason
which, in philosophical theory, are commonly confused with
others, and not properly distinguished even from concepts of
understanding, we have been able to rescue them from their
ambiguous position, to determine their origin, and at the
same time, in so doing, to fix their precise number (to which
we can never add), presenting them in a systematic connec-
tion, and so marking out and enclosing a special field for pure
P 327
ALTHOUGH a purely transcendental idea is, in accordance
with the original laws of reason, a quite necessary product of
reason, its object, it may yet be said, is something of which
we have no concept. For in respect of an object which is
adequate to the demands of reason, it is not, in fact, possible
that we should ever be able to form a concept of the under-
standing, that is, a concept that allows of being exhibited and
intuited in a possible experience. But we should be better
advised and less likely to be misunderstood if we said that
although we cannot have any knowledge of the object which
corresponds to an idea, we yet have a problematic concept
of it. 
The transcendental (subjective) reality of the pure concepts
of reason depends on our having been led to such ideas by a
necessary syllogism. There will therefore be syllogisms which
contain no empirical premisses, and by means of which we
conclude from something which we know to something else of
which we have no concept, and to which, owing to an inevitable
illusion, we yet ascribe objective reality. These conclusions
are, then, rather to be called pseudo-rational than rational,
although in view of their origin they may well lay claim to
the latter title, since they are not fictitious and have not arisen
fortuitously, but have sprung from the very nature of reason. 
They are sophistications not of men but of pure reason itself. 
Even the wisest of men cannot free himself from them. After
long effort he perhaps succeeds in guarding himself against
P 328
actual error; but he will never be able to free himself from the
illusion, which unceasingly mocks and torments him. 
There are, then, only three kinds of dialectical syllogisms
-- just so many as there are ideas in which their conclusions
result. In the first kind of syllogism I conclude from the
transcendental concept of the subject, which contains nothing
manifold, the absolute unity of this subject itself, of which,
however, even in so doing, I possess no concept whatsoever. 
This dialectical inference I shall entitle the transcendental
paralogism. The second kind of pseudo-rational inference is
directed to the transcendental concept of the absolute totality
of the series of conditions for any given appearance. From the
fact that my concept of the unconditioned synthetic unity of the
series, as thought in a certain way, is always self-contradictory,
I conclude that there is really a unity of the opposite kind,
although of it also I have no concept. The position of reason in
these dialectical inferences I shall entitle the antinomy of pure
reason. Finally, in the third kind of pseudo-rational inference,
from the totality of the conditions under which objects in
general, in so far as they can be given me, have to be thought,
I conclude to the absolute synthetic unity of all conditions of
the possibility of things in general, i.e. from things which I do
not know through the merely transcendental concept of them
I infer an ens entium, which I know even less through any
transcendental concept, and of the unconditioned necessity
of which I can form no concept whatsoever. This dialectical
syllogism I shall entitle the ideal of pure reason. 
A logical paralogism is a syllogism which is fallacious in
form, be its content what it may. A transcendental paralogism
is one in which there is a transcendental ground, constraining
us to draw a formally invalid conclusion. Such a fallacy is
P 329
therefore grounded in the nature of human reason, and gives
rise to an illusion which cannot be avoided, although it may,
indeed, be rendered harmless. 
We now come to a concept which was not included in the
general list of transcendental concepts but which must yet be
counted as belonging to that list, without, however, in the least
altering it or declaring it defective. This is the concept or, if the
term be preferred, the judgment, 'I think'. As is easily seen,
this is the vehicle of all concepts, and therefore also of tran-
scendental concepts, and so is always included in the conceiv-
ing of these latter, and is itself transcendental. But it can have
no special designation, because it serves only to introduce all our
thought, as belonging to consciousness. Meanwhile, however
free it be of empirical admixture (impressions of the senses),
it yet enables us to distinguish, through the nature of our
faculty of representation, two kinds of objects. 'I', as think-
ing, am an object of inner sense, and am called 'soul'. That
which is an object of the outer senses is called 'body'. Accord-
ingly the expression 'I', as a thinking being, signifies the
object of that psychology which may be entitled the 'rational
doctrine of the soul', inasmuch as I am not here seeking to
learn in regard to the soul anything more than can be in-
ferred, independently of all experience (which determines me
more specifically and in concreto), from this concept 'I', so
far as it is present in all thought. 
The rational doctrine of the soul is really an undertaking
of this kind; for if in this science the least empirical element
of my thought, or any special perception of my inner state,
were intermingled with the grounds of knowledge, it would
no longer be a rational but an empirical doctrine of the soul. 
Thus we have here what professes to be a science built upon
the single proposition 'I think'. Whether this claim be well or
ill grounded, we may, very fittingly, in accordance with the
nature of a transcendental philosophy, proceed to investi-
gate. The reader must not object that this proposition, which
expresses the perception of the self, contains an inner experi-
ence, and that the rational doctrine of the soul founded upon
it is never pure and is therefore to that extent based upon an
empirical principle. For this inner perception is nothing more
than the mere apperception 'I think', by which even tran-
P 330
scendental concepts are made possible; what we assert in them
is 'I think substance, cause', etc. For inner experience in
general and its possibility, or perception in general and its
relation to other perception, in which no special distinction
or empirical determination is given, is not to be regarded as
empirical knowledge but as knowledge of the empirical in
general, and has to be reckoned with the investigation of the
possibility of any and every experience, which is certainly a
transcendental enquiry. The least object of perception (for ex-
ample, even pleasure or displeasure), if added to the universal
representation of self-consciousness, would at once transform
rational psychology into empirical psychology. 
'I think' is, therefore, the sole text of rational psychology,
and from it the whole of its teaching has to be developed. 
Obviously, if this thought is to be related to an object (myself),
it can contain none but transcendental predicates of that ob-
ject, since the least empirical predicate would destroy the
rational purity of the science and its independence of all
 All that is here required is that we follow the guidance of
the categories, with this difference only, that since our starting-
point is a given thing, 'I' as thinking being, we begin with the
category of substance, whereby a thing in itself is represented,
and so proceed backwards through the series, without, how-
ever, otherwise changing the order adopted in the table of the
categories. The topic of the rational doctrine of the soul, from
which everything else that it contains must be derived, is
accordingly as follows:
The soul is substance. 
As regards its quality it is
As regards the different
times in which it exists, it is
numerically identical, that
is, unity (not plurality). 
P 331
It is in relation to possible objects in space. 
All the concepts of pure psychology arise from these ele-
ments, simply by way of combination, without admission of
any other principle. This substance, merely as object of inner
sense, gives the concept of immateriality; as simple substance,
that of incorruptibility; its identity, as intellectual substance,
personality; all these three together, spirituality; while the
relation to objects in space gives commercium with bodies,
and so leads us to represent the thinking substance as the
principle of life in matter, that is, as soul (anima), and as the
ground of animality. This last, in turn, as limited by spiritu-
ality, gives the concept of immortality. 
In connection with these concepts we have four paralogisms
of a transcendental psychology -- which is wrongly regarded as
a science of pure reason -- concerning the nature of our thinking
being. We can assign no other basis for this teaching than the
simple, and in itself completely empty, representation 'I'; and we
cannot even say that this is a concept, but only that it is a bare
consciousness which accompanies all concepts. Through this
I or he or it (the thing) which thinks, nothing further is repre-
sented than a transcendental subject of the thoughts = X. It
is known only through the thoughts which are its predicates,
and of it, apart from them, we cannot have any concept what-
soever, but can only revolve in a perpetual circle, since any
judgment upon it has always already made use of its repre-
++ The reader who has difficulty in guessing the psychological
meaning of these expressions taken in their transcendental abstract-
ness, and in discovering why the last-mentioned attribute of the soul
belongs to the category of existence, will find the terms sufficiently
explained and justified in the sequel. Further, I have to apologise
for the Latin expressions which, contrary to good taste, have usurped
the place of their German equivalents, both in this section and in the
work as a whole. My excuse is that I have preferred to lose somewhat
in elegance of language rather than to increase, in however minor
a degree, the reader's difficulties. 
P 331
And the reason why this inconvenience is insepar-
ably bound up with it, is that consciousness in itself is not a
representation distinguishing a particular object, but a form
P 332
of representation in general, that is, of representation in so far
as it is to be entitled knowledge; for it is only of knowledge
that I can say that I am thereby thinking something. 
It must, on first thoughts, seem strange that the condition
under which alone I think, and which is therefore merely a pro-
perty of myself as subject, should likewise be valid for every-
thing that thinks, and that on a seemingly empirical proposition
we can presume to base an apodeictic and universal judgment,
namely, that that which thinks must, in all cases, be constituted
as the voice of self-consciousness declares it to be constituted
in my own self. The reason is this: we must assign to things,
necessarily and a priori, all the properties that constitute the
conditions under which alone we think them. Now I cannot
have any representation whatsoever of a thinking being,
through any outer experience, but only through self-conscious-
ness. Objects of this kind are, therefore, nothing more than
the transference of this consciousness of mine to other things,
which in this way alone can be represented as thinking beings. 
The proposition, 'I think', is, however, here taken only prob-
lematically, not in so far as it may contain perception of an
existent (the Cartesian cogito, ergo sum), but in respect of its
mere possibility, in order to see what properties applicable to
its subject (be that subject actually existent or not) may follow
from so simple a proposition. 
If our knowledge of thinking beings in general, by means
of pure reason, were based on more than the cogito, if we
likewise made use of observations concerning the play of our
thoughts and the natural laws of the thinking self to be de-
rived from these thoughts, there would arise an empirical psy-
chology, which would be a kind of physiology of inner sense,
capable perhaps of explaining the appearances of inner sense,
but never of revealing such properties as do not in any way
belong to possible experience (e.g. the properties of the simple),
nor of yielding any apodeictic knowledge regarding the nature
of thinking beings in general. It would not, therefore, be a
rational psychology. 
 Since the proposition 'I think' (taken problematically) con-
tains the form of each and every judgment of the understand-
ing and accompanies all categories as their vehicle, it is evi-
dent that the inferences from it admit only of a transcendental
P 333
employment of the understanding. And since this employment
excludes any admixture of experience, we cannot, after what
has been shown above, entertain any favourable anticipations
in regard to its methods of procedure. We therefore propose to
follow it, with a critical eye, through all the predicaments of
pure psychology. 
That, the representation of which is the absolute subject of
our judgments and cannot therefore be employed as deter-
mination of another thing, is substance. 
I, as a thinking being, am the absolute subject of all my
possible judgments, and this representation of myself cannot
be employed as predicate of any other thing. 
Therefore I, as thinking being (soul), am substance. 
Critique of the First Paralogism of Pure Psychology 
In the analytical part of the Transcendental Logic we have
shown that pure categories, and among them that of sub-
stance, have in themselves no objective meaning, save in so far
as they rest upon an intuition, and are applied to the manifold
of this intuition, as functions of synthetic unity. In the ab-
sence of this manifold, they are merely functions of a judg-
ment, without content. I can say of any and every thing that
it is substance, in the sense that I distinguish it from mere
predicates and determinations of things. Now in all our
thought the 'I' is the subject, in which thoughts inhere only
as determinations; and this 'I' cannot be employed as the
determination of another thing. Everyone must, therefore,
necessarily regard himself as substance, and thought as [con-
sisting] only [in] accidents of his being, determinations of his
But what use am I to make of this concept of a substance? 
That I, as a thinking being, persist for myself, and do not in
any natural manner either arise or perish, can by no means be
P 334
deduced from it. Yet there is no other use to which I can put
the concept of the substantiality of my thinking subject, and
apart from such use I could very well dispense with it. 
So far from being able to deduce these properties merely
from the pure category of substance, we must, on the contrary,
take our start from the permanence of an object given in ex-
perience as permanent. For only to such an object can the
concept of substance be applied in a manner that is empiric-
ally serviceable. In the above proposition, however, we have
not taken as our basis any experience; the inference is merely
from the concept of the relation which all thought has to the
'I' as the common subject in which it inheres. Nor should we, in
resting it upon experience, be able, by any sure observation, to
demonstrate such permanence. The 'I' is indeed in all thoughts,
but there is not in this representation the least trace of intui-
tion, distinguishing the 'I' from other objects of intuition. 
Thus we can indeed perceive that this representation is invari-
ably present in all thought, but not that it is an abiding and
continuing intuition, wherein the thoughts, as being transitory,
give place to one another. 
It follows, therefore, that the first syllogism of tran-
scendental psychology, when it puts forward the constant logi-
cal subject of thought as being knowledge of the real subject
in which the thought inheres, is palming off upon us what is
a mere pretence of new insight. We do not have, and cannot
have, any knowledge whatsoever of any such subject. Con-
sciousness is, indeed, that which alone makes all representa-
tions to be thoughts, and in it, therefore, as the transcendental
subject, all our perceptions must be found; but beyond this
logical meaning of the 'I', we have no knowledge of the sub-
ject in itself, which as substratum underlies this 'I', as it does
all thoughts. The proposition, 'The soul is substance', may,
however, quite well be allowed to stand, if only it be recog-
nised that this concept [of the soul as substance] does not
carry us a single step further, and so cannot yield us any of the
usual deductions of the pseudo-rational doctrine of the soul,
as, for instance, the everlasting duration of the human soul in
all changes and even in death -- if, that is to say, we recognise
that this concept signifies a substance only in idea, not in reality. 
P 335
That, the action of which can never be regarded as the
concurrence of several things acting, is simple. 
Now the soul, or the thinking 'I', is such a being. There-
fore, etc. 
Critique of the Second Paralogism of Transcendental
This is the Achilles of all dialectical inferences in the pure
doctrine of the soul. It is no mere sophistical play, contrived
by a dogmatist in order to impart to his assertions a super-
ficial plausibility, but an inference which appears to with-
stand even the keenest scrutiny and the most scrupulously
exact investigation. It is as follows. 
Every composite substance is an aggregate of several sub-
stances, and the action of a composite, or whatever inheres in
it as thus composite, is an aggregate of several actions or acci-
dents, distributed among the plurality of the substances. Now
an effect which arises from the concurrence of many acting
substances is indeed possible, namely, when this effect is
external only (as, for instance, the motion of a body is the
combined motion of all its parts). But with thoughts, as in-
ternal accidents belonging to a thinking being, it is different. 
For suppose it be the composite that thinks: then every part of
it would be a part of the thought, and only all of them taken
together would contain the whole thought. But this cannot con-
sistently be maintained. For representations (for instance, the
single words of a verse), distributed among different beings,
never make up a whole thought (a verse), and it is therefore
impossible that a thought should inhere in what is essentially
composite. It is therefore possible only in a single substance,
which, not being an aggregate of many, is absolutely simple. 
++ This proof can very easily be given the customary syllogistic
correctness of form. But for my purpose it is sufficient to have made
clear, though in popular fashion, the bare ground of proof. 
P 335
The so-called nervus probandi of this argument lies in the
proposition, that if a multiplicity of representations are to
form a single representation, they must be contained in the
P 336
absolute unity of the thinking subject. No one, however, can prove this
proposition from concepts. For how should he set about the task of achiev-
ing this? The proposition, 'A thought can only be the effect
of the absolute unity of the thinking being', cannot be treated
as analytic. For the unity of the thought, which consists of
many representations, is collective, and as far as mere con-
cepts can show, may relate just as well to the collective unity
of different substances acting together (as the motion of a
body is the composite motion of all its parts) as to the absolute
unity of the subject. Consequently, the necessity of presuppos-
ing, in the case of a composite thought, a simple substance,
cannot be demonstrated in accordance with the principle of
identity. Nor will anyone venture to assert that the proposi-
 tion allows of being known synthetically and completely
a priori from mere concepts -- not, at least, if he understands
the ground of the possibility of a priori synthetic propositions,
as above explained. 
It is likewise impossible to derive this necessary unity of
the subject, as a condition of the possibility of every thought,
from experience. For experience yields us no knowledge of
necessity, apart even from the fact that the concept of absolute
unity is quite outside its province. Whence then are we to
derive this proposition upon which the whole psychological
syllogism depends? 
It is obvious that, if I wish to represent to myself a think-
ing being, I must put myself in his place, and thus substitute,
as it were, my own subject for the object I am seeking to
consider (which does not occur in any other kind of investiga-
tion), and that we demand the absolute unity of the subject of
a thought, only because otherwise we could not say, 'I think'
(the manifold in a representation). For although the whole of
the thought could be divided and distributed among many
subjects, the subjective 'I' can never be thus divided and
distributed, and it is this 'I' that we presuppose in all
Here again, as in the former paralogism, the formal pro-
position of apperception, 'I think', remains the sole ground to
which rational psychology can appeal when it thus ventures
upon an extension of its knowledge. This proposition, how-
ever, is not itself an experience, but the form of apperception,
P 337
which belongs to and precedes every experience; and as such
it must always be taken only in relation to some possible
knowledge, as a merely subjective condition of that know-
ledge. We have no right to transform it into a condition of the
possibility of a knowledge of objects, that is, into a concept of
thinking being in general. For we are not in a position to re-
present such being to ourselves save by putting ourselves,
with the formula of our consciousness, in the place of every
other intelligent being. 
Nor is the simplicity of myself (as soul) really inferred
from the proposition, 'I think'; it is already involved in every
thought. The proposition, 'I am simple', must be regarded as
an immediate expression of apperception, just as what is
referred to as the Cartesian inference, cogito, ergo sum, is
really a tautology, since the cogito (sum cogitans) asserts my
existence immediately. 'I am simple' means nothing more
than that this representation, 'I', does not contain in itself the
least manifoldness and that it is absolute (although merely
logical) unity. 
Thus the renowned psychological proof is founded merely
on the indivisible unity of a representation, which governs
only the verb in its relation to a person. It is obvious that in
attaching 'I' to our thoughts we designate the subject of in-
herence only transcendentally, without noting in it any quality
whatsoever -- in fact, without knowing anything of it either by
direct acquaintance or otherwise. It means a something in
general (transcendental subject), the representation of which
must, no doubt, be simple, if only for the reason that there is
nothing determinate in it. Nothing, indeed, can be represented
that is simpler than that which is represented through the
concept of a mere something. But the simplicity of the repre-
sentation of a subject is not eo ipso knowledge of the simplicity
of the subject itself, for we abstract altogether from its pro-
perties when we designate it solely by the entirely empty
expression 'I', an expression which I can apply to every
thinking subject. 
This much, then, is certain, that through the 'I', I always
P 338
entertain the thought of an absolute, but logical, unity of the
subject (simplicity). It does not, however, follow that I thereby
know the actual simplicity of my subject. The proposition, 'I
am substance', signifies, as we have found, nothing but the
pure category, of which I can make no use (empirically) in
concreto; and I may therefore legitimately say: 'I am a simple
substance', that is, a substance the representation of which never
contains a synthesis of the manifold. But this concept, as also
the proposition, tells us nothing whatsoever in regard to my-
self as an object of experience, since the concept of substance
is itself used only as a function of synthesis, without any under-
lying intuition, and therefore without an object. It concerns
only the condition of our knowledge; it does not apply to any
assignable object. We will test the supposed usefulness of the
proposition by an experiment. 
Everyone must admit that the assertion of the simple nature
of the soul is of value only in so far as I can thereby dis-
tinguish this subject from all matter, and so can exempt it
from the dissolution to which matter is always liable. This is
indeed, strictly speaking, the only use for which the above
proposition is intended, and is therefore generally expressed
as 'The soul is not corporeal'. If, then, I can show that,
although we allow full objective validity -- the validity ap-
propriate to a judgment of pure reason derived solely from
pure categories -- to this cardinal proposition of the rational
doctrine of the soul (that is, that everything which thinks is a
simple substance), we still cannot make the least use of this
proposition in regard to the question of its dissimilarity from
or relation to matter, this will be the same as if I had relegated
this supposed psychological insight to the field of mere ideas,
without any real objective use. 
In the Transcendental Aesthetic we have proved, beyond
all question, that bodies are mere appearances of our outer
sense and not things in themselves. We are therefore justified
in saying that our thinking subject is not corporeal; in other
words, that, inasmuch as it is represented by us as object of
inner sense, it cannot, in so far as it thinks, be an object of
outer sense, that is, an appearance in space. This is equivalent
to saying that thinking beings, as such, can never be found by
us among outer appearances, and that their thoughts, con-
P 339
sciousness, desires, etc. , cannot be outwardly intuited. All these
belong to inner sense. This argument does, in fact, seem to
be so natural and so popular that even the commonest under-
standing appears to have always relied upon it, and thus al-
ready, from the earliest times, to have regarded souls as quite
different entities from their bodies. 
But although extension, impenetrability, cohesion, and
motion -- in short, everything which outer senses can give us
-- neither are nor contain thoughts, feeling, desire, or resolu-
tion, these never being objects of outer intuition, nevertheless
the something which underlies the outer appearances and
which so affects our sense that it obtains the representations
of space, matter, shape, etc. , may yet, when viewed as nou-
menon (or better, as transcendental object), be at the same
time the subject of our thoughts. That the mode in which
our outer sense is thereby affected gives us no intuition of re-
presentations, will, etc. , but only of space and its determina-
tions, proves nothing to the contrary. For this something is
not extended, nor is it impenetrable or composite, since all
these predicates concern only sensibility and its intuition, in
so far as we are affected by certain (to us otherwise unknown)
objects. By such statements we are not, however, enabled
to know what kind of an object it is, but only to recognise
that if it be considered in itself, and therefore apart from any
relation to the outer senses, these predicates of outer appear-
ances cannot be assigned to it. On the other hand, the predi-
cates of inner sense, representations and thought, are not
inconsistent with its nature. Accordingly, even granting the
human soul to be simple in nature, such simplicity by no
means suffices to distinguish it from matter, in respect of
the substratum of the latter -- if, that is to say, we consider
matter, as indeed we ought to, as mere appearance. 
If matter were a thing in itself, it would, as a composite
being, be entirely different from the soul, as a simple being. But
matter is mere outer appearance, the substratum of which can-
not be known through any predicate that we can assign to it. 
I can therefore very well admit the possibility that it is in itself
simple, although owing to the manner in which it affects our
senses it produces in us the intuition of the extended and so of
P 340
the composite. I may further assume that the substance which
in relation to our outer sense possesses extension is in itself the
possessor of thoughts, and that these thoughts can by means of
its own inner sense be consciously represented. In this way,
what in one relation is entitled corporeal would in another
relation be at the same time a thinking being, whose thoughts
we cannot intuit, though we can indeed intuit their signs in
the [field of] appearance. Accordingly, the thesis that only
souls (as particular kinds of substances) think, would have
to be given up; and we should have to fall back on the
common expression that men think, that is, that the very
same being which, as outer appearance, is extended, is (in
itself) internally a subject, and is not composite, but is simple
and thinks. 
But, without committing ourselves in regard to such hypo-
theses, we can make this general remark. If I understand by
soul a thinking being in itself, the question whether or not it is
the same in kind as matter -- matter not being a thing in itself,
but merely a species of representations in us -- is by its very
terms illegitimate. For it is obvious that a thing in itself is of a
different nature from the determinations which constitute only
its state. 
If, on the other hand, we compare the thinking 'I' not with
matter but with the intelligible that lies at the basis of the
outer appearance which we call matter, we have no knowledge
whatsoever of the intelligible, and therefore are in no position
to say that the soul is in any inward respect different from it. 
The simple consciousness is not, therefore, knowledge of
the simple nature of the self as subject, such as might enable us
to distinguish it from matter, as from a composite being. 
If, therefore, in the only case in which this concept can be
of service, namely, in the comparison of myself with objects of
outer experience, it does not suffice for determining what is
specific and distinctive in the nature of the self, then though
we may still profess to know that the thinking 'I', the soul (a
name for the transcendental object of inner sense), is simple,
such a way of speaking has no sort of application to real ob-
jects, and therefore cannot in the least extend our knowledge. 
P 341
Thus the whole of rational psychology is involved in the
collapse of its main support. Here as little as elsewhere can we
hope to extend our knowledge through mere concepts -- still
less by means of the merely subjective form of all our concepts,
consciousness -- in the absence of any relation to possible ex-
perience. For [as we have thus found], even the fundamental
concept of a simple nature is such that it can never be met
with in any experience, and such, therefore, that there is no
way of attaining to it, as an objectively valid concept. 
That which is conscious of the numerical identity of itself
at different times is in so far a person. 
Now the soul is conscious, etc. 
Therefore it is a person. 
Critique of the Third Paralogism of Transcendental
If I want to know through experience, the numerical iden-
tity of an external object, I shall pay heed to that permanent
element in the appearance to which as subject everything else
is related as determination, and note its identity throughout the
time in which the determinations change. Now I am an object
of inner sense, and all time is merely the form of inner sense. 
Consequently, I refer each and all of my successive determina-
tions to the numerically identical self, and do so throughout
time, that is, in the form of the inner intuition of myself. This
being so, the personality of the soul has to be regarded not as
inferred but as a completely identical proposition of self-con-
sciousness in time; and this, indeed, is why it is valid a priori. 
For it really says nothing more than that in the whole time in
which I am conscious of myself, I am conscious of this time as
belonging to the unity of myself; and it comes to the same
whether I say that this whole time is in me, as individual unity,
or that I am to be found as numerically identical in all this time. 
In my own consciousness, therefore, identity of person is
unfailingly met with. But if I view myself from the standpoint
of another person (as object of his outer intuition), it is this
P 342
outer observer who first represents me in time, for in the apper-
ception time is represented, strictly speaking, only in me. Al-
though he admits, therefore, the 'I', which accompanies, and
indeed with complete identity, all representations at all times
in my consciousness, he will draw no inference from this to the
objective permanence of myself. For just as the time in which
the observer sets me is not the time of my own but of his sensi-
bility, so the identity which is necessarily bound up with my
consciousness is not therefore bound up with his, that is, with
the consciousness which contains the outer intuition of my
The identity of the consciousness of myself at different
times is therefore only a formal condition of my thoughts and
their coherence, and in no way proves the numerical identity of
my subject. Despite the logical identity of the 'I', such a change
may have occurred in it as does not allow of the retention of
its identity, and yet we may ascribe to it the same-sounding
'I', which in every different state, even in one involving change
of the [thinking] subject, might still retain the thought of the
preceding subject and so hand it over to the subsequent
 Although the dictum of certain ancient schools, that every-
thing in the world is in a flux and nothing is permanent and
abiding, cannot be reconciled with the admission of sub-
stances, it is not refuted by the unity of self-consciousness. 
++ An elastic ball which impinges on another similar ball in a
straight line communicates to the latter its whole motion, and there-
fore its whole state (that is, if we take account only of the positions
in space). If, then, in analogy with such bodies, we postulate sub-
stances such that the one communicates to the other representations
together with the consciousness of them, we can conceive a whole
series of substances of which the first transmits its state together
with its consciousness to the second, the second its own state with
that of the preceding substance to the third, and this in turn the
states of all the preceding substances together with its own conscious-
ness and with their consciousness to another. The last substance
would then be conscious of all the states of the previously changed
substances, as being its own states, because they would have been
transferred to it together with the consciousness of them. And yet it
would not have been one and the same person in all these states. 
P 343
For we are unable from our own consciousness to determine
whether, as souls, we are permanent or not. Since we reckon
as belonging to our identical self only that of which we are
conscious, we must necessarily judge that we are one and the
same throughout the whole time of which we are conscious. 
We cannot, however, claim that this judgment would be valid
from the standpoint of an outside observer. For since the only
permanent appearance which we encounter in the soul is the
representation 'I' that accompanies and connects them all, we
are unable to prove that this 'I', a mere thought, may not be
in the same state of flux as the other thoughts which, by
means of it, are linked up with one another. 
It is indeed strange that personality, and its presupposi-
tion, permanence, and therefore the substantiality of the soul,
should have to be proved at this stage and not earlier. For
could we have presupposed these latter [permanence and sub-
stantiality], there would follow, not indeed the continuance of
consciousness, yet at least the possibility of a continuing con-
sciousness in an abiding subject, and that is already sufficient
for personality. For personality does not itself at once cease
because its activity is for a time interrupted. This permanence,
however, is in no way given prior to that numerical identity
of our self which we infer from identical apperception, but
on the contrary is inferred first from the numerical identity. 
(If the argument proceeded aright, the concept of substance,
which is applicable only empirically, would first be brought
in after such proof of numerical identity. ) Now, since this
identity of person [presupposing, as it does, numerical iden-
tity] in nowise follows from the identity of the 'I' in the con-
sciousness of all the time in which I know myself, we could
not, earlier in the argument, have founded upon it the sub-
stantiality of the soul. 
Meanwhile we may still retain the concept of personality
just as we have retained the concept of substance and of the
simple -- in so far as it is merely transcendental, that is, con-
cerns the unity of the subject, otherwise unknown to us,
in the determinations of which there is a thoroughgoing
connection through apperception. Taken in this way, the con-
cept is necessary for practical employment and is sufficient for
P 344
such use; but we can never parade it as an extension of our
self-knowledge through pure reason, and as exhibiting to us
from the mere concept of the identical self an unbroken con-
tinuance of the subject. For this concept revolves perpetually
in a circle, and does not help us in respect to any question
which aims at synthetic knowledge. What matter may be as a
thing in itself (transcendental object) is completely unknown
to us, though, owing to its being represented as something ex-
ternal, its permanence as appearance can indeed be observed. 
But if I want to observe the mere 'I' in the change of all repre-
sentations, I have no other correlatum to use in my comparisons
except again myself, with the universal conditions of my con-
sciousness. Consequently, I can give none but tautological
answers to all questions, in that I substitute my concept and
its unity for the properties which belong to myself as object,
and so take for granted that which the questioner has desired
to know. 
That, the existence of which can only be inferred as a cause
of given perceptions, has a merely doubtful existence. 
 Now all outer appearances are of such a nature that their
existence is not immediately perceived, and that we can only
infer them as the cause of given perceptions. 
Therefore the existence of all objects of the outer senses is
doubtful. This uncertainty I entitle the ideality of outer appear-
ances, and the doctrine of this ideality is called idealism, as
distinguished from the counter-assertion of a possible certainty
in regard to objects of outer sense, which is called dualism. 
Critique of the Fourth Paralogism of Transcendental
Let us first examine the premisses. We are justified, [it is
argued], in maintaining that only what is in ourselves can be
perceived immediately, and that my own existence is the sole
object of a mere perception. The existence, therefore, of an
actual object outside me (if this word 'me' be taken in the
P 345
intellectual [not in the empirical] sense) is never given directly
in perception. Perception is a modification of inner sense, and
the existence of the outer object can be added to it only in
thought, as being its outer cause, and accordingly as being
inferred. For the same reason, Descartes was justified in
limiting all perception, in the narrowest sense of that term, to
the proposition, 'I, as a thinking being, exist. ' Obviously, since
what is without is not in me, I cannot encounter it in my
apperception, nor therefore in any perception, which, properly
regarded, is merely the determination of apperception. 
I am not, therefore, in a position to perceive external things,
but can only infer their existence from my inner perception,
taking the inner perception as the effect of which something
external is the proximate cause. Now the inference from a
given effect to a determinate cause is always uncertain, since
the effect may be due to more than one cause. Accordingly, as
regards the relation of the perception to its cause, it always
remains doubtful whether the cause be internal or external;
whether, that is to say, all the so-called outer perceptions are
not a mere play of our inner sense, or whether they stand in
relation to actual external objects as their cause. At all events,
the existence of the latter is only inferred, and is open to all
the dangers of inference, whereas the object of inner sense (I
myself with all my representations) is immediately perceived,
and its existence does not allow of being doubted. 
The term 'idealist' is not, therefore, to be understood as
applying to those who deny the existence of external objects
of the senses, but only to those who do not admit that their
existence is known through immediate perception, and who
therefore conclude that we can never, by way of any possible
experience, be completely certain as to their reality. 
Before exhibiting our paralogism in all its deceptive
illusoriness, I have first to remark that we must necessarily
distinguish two types of idealism, the transcendental and the
empirical. By transcendental idealism I mean the doctrine
that appearances are to be regarded as being, one and all,
representations only, not things in themselves, and that time
and space are therefore only sensible forms of our intuition,
not determinations given as existing by themselves, nor con-
ditions of objects viewed as things in themselves. To this ideal-
P 346
ism there is opposed a transcendental realism which regards
time and space as something given in themselves, independ-
ently of our sensibility. The transcendental realist thus inter-
prets outer appearances (their reality being taken as granted)
as things-in-themselves, which exist independently of us and of
our sensibility, and which are therefore outside us -- the phrase
'outside us' being interpreted in conformity with pure con-
cepts of understanding. It is, in fact, this transcendental realist
who afterwards plays the part of empirical idealist. After
wrongly supposing that objects of the senses, if they are to be
external, must have an existence by themselves, and inde-
pendently of the senses, he finds that, judged from this point
of view, all our sensuous representations are inadequate to
establish their reality. 
 The transcendental idealist, on the other hand, may be an
empirical realist or, as he is called, a dualist; that is, he may
admit the existence of matter without going outside his mere
self-consciousness, or assuming anything more than the cer-
tainty of his representations, that is, the cogito, ergo sum. For
he considers this matter and even its inner possibility to be
appearance merely; and appearance, if separated from our
sensibility, is nothing. Matter is with him, therefore, only a
species of representations (intuition), which are called external,
not as standing in relation to objects in themselves external,
but because they relate perceptions to the space in which all
things are external to one another, while yet the space itself is
in us. 
From the start, we have declared ourselves in favour of
this transcendental idealism; and our doctrine thus removes
all difficulty in the way of accepting the existence of matter
on the unaided testimony of our mere self-consciousness, or of
declaring it to be thereby proved in the same manner as the
existence of myself as a thinking being is proved. There can
be no question that I am conscious of my representations;
these representations and I myself, who have the representa-
tions, therefore exist. External objects (bodies), however, are
mere appearances, and are therefore nothing but a species of
my representations, the objects of which are something only
through these representations. Apart from them they are
nothing. Thus external things exist as well as I myself, and
P 347
both indeed, upon the immediate witness of my self-conscious-
ness. The only difference is that the representation of myself,
as the thinking subject, belongs to inner sense only, while
the representations which mark extended beings belong also
to outer sense. In order to arrive at the reality of outer objects
I have just as little need to resort to inference as I have in re-
gard to the reality of the object of my inner sense, that is, in
regard to the reality of my thoughts. For in both cases alike the
objects are nothing but representations, the immediate per-
ception (consciousness) of which is at the same time a suffi-
cient proof of their reality. 
The transcendental idealist is, therefore, an empirical real-
ist, and allows to matter, as appearance, a reality which does
not permit of being inferred, but is immediately perceived. 
Transcendental realism, on the other hand, inevitably falls
into difficulties, and finds itself obliged to give way to em-
pirical idealism, in that it regards the objects of outer sense as
something distinct from the senses themselves, treating mere
appearances as self-subsistent beings, existing outside us. On
such a view as this, however clearly we may be conscious of
our representation of these things, it is still far from certain
that, if the representation exists, there exists also the object
corresponding to it. In our system, on the other hand, these
external things, namely matter, are in all their configurations
and alterations nothing but mere appearances, that is, repre-
sentations in us, of the reality of which we are immediately
Since, so far as I know, all psychologists who adopt em-
pirical idealism are transcendental realists, they have cer-
tainly proceeded quite consistently in ascribing great import-
ance to empirical idealism, as one of the problems in regard to
which the human mind is quite at a loss how to proceed. For
if we regard outer appearances as representations produced in
us by their objects, and if these objects be things existing in
themselves outside us, it is indeed impossible to see how we can
come to know the existence of the objects otherwise than by in-
ference from the effect to the cause; and this being so, it must
always remain doubtful whether the cause in question be in
us or outside us. We can indeed admit that something, which
P 348
may be (in the transcendental sense) outside us, is the cause of
our outer intuitions, but this is not the object of which we are
thinking in the representations of matter and of corporeal
things; for these are merely appearances, that is, mere kinds of
representation, which are never to be met with save in us, and
the reality of which depends on immediate consciousness, just
as does the consciousness of my own thoughts. The transcend-
ental object is equally unknown in respect to inner and to
outer intuition. But it is not of this that we are here speaking,
but of the empirical object, which is called an external object
if it is represented in space, and an inner object if it is repre-
sented only in its time-relations. Neither space nor time, how-
ever, is to be found save in us. 
The expression 'outside us' is thus unavoidably ambiguous
in meaning, sometimes signifying what as thing in itself exists
apart from us, and sometimes what belongs solely to outer
appearance. In order, therefore, to make this concept, in the
latter sense -- the sense in which the psychological question as
to the reality of our outer intuition has to be understood --
quite unambiguous, we shall distinguish empirically external
objects from those which may be said to be external in the
transcendental sense, by explicitly entitling the former 'things
which are to be found in space'. 
Space and time are indeed a priori representations, which
dwell in us as forms of our sensible intuition, before any real
object, determining our sense through sensation, has enabled
us to represent the object under those sensible relations. But
the material or real element, the something which is to be
intuited in space, necessarily presupposes perception. Per-
ception exhibits the reality of something in space; and in the
absence of perception no power of imagination can invent and
produce that something. It is sensation, therefore, that indicates
a reality in space or in time, according as it is related to the one
or to the other mode of sensible intuition. (Once sensation is
given -- if referred to an object in general, though not as deter-
mining that object, it is entitled perception -- thanks to its mani-
foldness we can picture in imagination many objects which have
no empirical place in space or time outside the imagination. )
P 349
This admits of no doubt; whether we take pleasure and pain,
or the sensations of the outer senses, colours, heat, etc. , per-
ception is that whereby the material required to enable us to
think objects of sensible intuition must first be given. This
perception, therefore (to consider, for the moment, only outer
intuitions), represents something real in space. For, in the first
place, while space is the representation of a mere possibility
of coexistence, perception is the representation of a reality. 
Secondly, this reality is represented in outer sense, that is, in
space. Thirdly, space is itself nothing but mere representation,
and therefore nothing in it can count as real save only what
is represented in it; and conversely, what is given in it, that
is, represented through perception, is also real in it. For if it
were not real, that is, immediately given through empirical
intuition, it could not be pictured in imagination, since what
is real in intuitions cannot be invented a priori. 
All outer perception, therefore, yields immediate proof of
something real in space, or rather is the real itself. In this
sense empirical realism is beyond question; that is, there
corresponds to our outer intuitions something real in space. 
Space itself, with all its appearances, as representations, is,
indeed, only in me, but nevertheless the real, that is, the
material of all objects of outer intuition, is actually given in this
space, independently of all imaginative invention. Also, it is
impossible that in this space anything outside us (in the tran-
scendental sense) should be given, space itself being nothing
outside our sensibility. Even the most rigid idealist cannot,
therefore, require a proof that the object outside us (taking
'outside' in the strict [transcendental] sense) corresponds to
our perception. 
++ We must give full credence to this paradoxical but correct pro-
position, that there is nothing in space save what is represented in it. 
For space is itself nothing but representation, and whatever is in it
must therefore be contained in the representation. Nothing whatso-
ever is in space, save in so far as it is actually represented in it. It is
a proposition which must indeed sound strange, that a thing can exist
only in the representation of it, but in this case the objection falls,
inasmuch as the things with which we are here concerned are not
things in themselves, but appearances only, that is, representations. 
P 349
For if there be any such object, it could not be
P 350
represented and intuited as outside us, because such repre-
sentation and intuition presuppose space, and reality in space,
being the reality of a mere representation, is nothing other
than perception itself. The real of outer appearances is there-
fore real in perception only, and can be real in no other way. 
From perceptions knowledge of objects can be generated,
either by mere play of imagination or by way of experience;
and in the process there may, no doubt, arise illusory repre-
sentations to which the objects do not correspond, the decep-
tion being attributable sometimes to a delusion of imagination
(in dreams) and sometimes to an error of judgment in so-called
sense-deception). To avoid such deceptive illusion, we have
to proceed according to the rule: Whatever is connected with a
perception according to empirical laws, is actual. But such
deception, as well as the provision against it, affects idealism
quite as much as dualism, inasmuch as we are concerned only
with the form of experience. Empirical idealism, and its mis-
taken questionings as to the objective reality of our outer
perceptions, is already sufficiently refuted, when it has been
shown that outer perception yields immediate proof of some-
thing actual in space, and that this space, although in itself
only a mere form of representations, has objective reality in
relation to all outer appearances, which also are nothing else
than mere representations; and when it has likewise been
shown that in the absence of perception even imagining and
dreaming are not possible, and that our outer senses, as regards
the data from which experience can arise, have therefore their
actual corresponding objects in space. 
The dogmatic idealist would be one who denies the exist-
ence of matter, the sceptical idealist one who doubts its exist-
ence, because holding it to be incapable of proof. The former
must base his view on supposed contradictions in the pos-
sibility of there being such a thing as matter at all -- a view
with which we have not yet been called upon to deal. The
following section on dialectical inferences, which represents
reason as in strife with itself in regard to the concepts which
it makes for itself of the possibility of what belongs to the
P 351
connection of experience, will remove this difficulty. The
sceptical idealist, however, who merely challenges the ground
of our assertion and denounces as insufficiently justified our
conviction of the existence of matter, which we thought to
base on immediate perception, is a benefactor of human
reason in so far as he compels us, even in the smallest ad-
vances of ordinary experience, to keep on the watch, lest we
consider as a well-earned possession what we perhaps obtain
only illegitimately. We are now in a position to appreciate
the value of these idealist objections. Unless we mean to
contradict ourselves in our commonest assertions, they drive
us by main force to view all our perceptions, whether we
call them inner or outer, as a consciousness only of what is
dependent on our sensibility. They also compel us to view the
outer objects of these perceptions not as things in themselves,
but only as representations, of which, as of every other repre-
sentation, we can become immediately conscious, and which
are entitled outer because they depend on what we call 'outer
sense', whose intuition is space. Space itself, however, is noth-
ing but an inner mode of representation in which certain
perceptions are connected with one another. 
If we treat outer objects as things in themselves, it is quite
impossible to understand how we could arrive at a knowledge
of their reality outside us, since we have to rely merely on
the representation which is in us. For we cannot be sentient
[of what is] outside ourselves, but only [of what is] in us, and
the whole of our self-consciousness therefore yields nothing
save merely our own determinations. Sceptical idealism thus
constrains us to have recourse to the only refuge still open,
namely, the ideality of all appearances, a doctrine which
has already been established in the Transcendental Aesthetic
independently of these consequences, which we could not at
that stage foresee. If then we ask, whether it follows that in the
doctrine of the soul dualism alone is tenable, we must answer:
'Yes, certainly; but dualism only in the empirical sense'. That
is to say, in the connection of experience matter, as substance
in the [field of] appearance, is really given to outer sense, just as
the thinking 'I', also as substance in the [field of] appearance,
is given to inner sense. Further, appearances in both fields
P 352
must be connected with each other according to the rules which
this category introduces into that connection of our outer as
well as of our inner perceptions whereby they constitute one ex-
perience. If, however, as commonly happens, we seek to extend
the concept of dualism, and take it in the transcendental sense,
neither it nor the two counter-alternatives -- pneumatism on
the one hand, materialism on the other -- would have any sort
of basis, since we should then have misapplied our concepts,
taking the difference in the mode of representing objects, which,
as regards what they are in themselves, still remain unknown
to us, as a difference in the things themselves. Though the 'I',
as represented through inner sense in time, and objects in space
outside me, are specifically quite distinct appearances, they
are not for that reason thought as being different things. 
Neither the transcendental object which underlies outer ap-
pearances nor that which underlies inner intuition, is in itself
either matter or a thinking being, but a ground (to us un-
known) of the appearances which supply to us the empirical
concept of the former as well as of the latter mode of exist-
If then, as this critical argument obviously compels us to
do, we hold fast to the rule above established, and do not push
our questions beyond the limits within which possible experi-
ence can present us with its object, we shall never dream of
seeking to inform ourselves about the objects of our senses as
they are in themselves, that is, out of all relation to the senses. 
But if the psychologist takes appearances for things in them-
selves, and as existing in and by themselves, then whether he
be a materialist who admits into his system nothing but matter
alone, or a spiritualist who admits only thinking beings (that
is, beings with the form of our inner sense), or a dualist who
accepts both, he will always, owing to this misunderstanding,
be entangled in pseudo-rational speculations as to how that
which is not a thing in itself, but only the appearance of a
thing in general, can exist by itself. 
 Consideration of Pure Psychology as a whole,
in view of these Paralogisms 
If we compare the doctrine of the soul as the physiology of
inner sense, with the doctrine of the body as a physiology of
P 353
the object of the outer senses, we find that while in both much
can be learnt empirically, there is yet this notable difference
In the latter science much that is a priori can be synthetically
known from the mere concept of an extended impenetrable
being, but in the former nothing whatsoever that is a priori
can be known synthetically from the concept of a thinking
being. The cause is this. Although both are appearances,
the appearance to outer sense has something fixed or abiding
which supplies a substratum as the basis of its transitory
determinations and therefore a synthetic concept, namely,
that of space and of an appearance in space; whereas time,
which is the sole form of our inner intuition, has nothing
abiding, and therefore yields knowledge only of the change
of determinations, not of any object that can be thereby deter-
mined. For in what we entitle 'soul', everything is in con-
tinual flux and there is nothing abiding except (if we must so
express ourselves) the 'I', which is simple solely because its
representation has no content, and therefore no manifold, and
for this reason seems to represent, or (to use a more correct
term) denote, a simple object. In order that it should be possible,
by pure reason, to obtain knowledge of the nature of a thinking
being in general, this 'I' would have to be an intuition which,
in being presupposed in all thought (prior to all experience),
might as intuition yield a priori synthetic propositions. This
'I' is, however, as little an intuition as it is a concept of any
object; it is the mere form of consciousness, which can accom-
pany the two kinds of representation and which is in a position
to elevate them to the rank of knowledge only in so far as some-
thing else is given in intuition which provides material for a
representation of an object. Thus the whole of rational psy-
chology, as a science surpassing all powers of human reason,
proves abortive, and nothing is left for us but to study our soul
under the guidance of experience, and to confine ourselves
to those questions which do not go beyond the limits within
which a content can be provided for them by possible inner
But although rational psychology cannot be used to extend
knowledge, and when so employed is entirely made up of
value, if it is taken as nothing more than a critical treatment
P 354
of our dialectical inferences, those that arise from the common
and natural reason of men. 
 Why do we have resort to a doctrine of the soul founded
exclusively on pure principles of reason? Beyond all doubt,
chiefly in order to secure our thinking self against the danger
of materialism. This is achieved by means of the pure con-
cept of our thinking self which we have just given. For by
this teaching so completely are we freed from the fear that on
the removal of matter all thought, and even the very existence
of thinking beings, would be destroyed, that on the contrary
it is clearly shown, that if I remove the thinking subject the
whole corporeal world must at once vanish: it is nothing save
an appearance in the sensibility of our subject and a mode
of its representations. 
I admit that this does not give me any further knowledge
of the properties of this thinking self, nor does it enable me to
determine its permanence or even that it exists independently
of what we may conjecture to be the transcendental sub-
stratum of outer appearances; for the latter is just as un-
known to me as is the thinking self. But it is nevertheless
possible that I may find cause, on other than merely specu-
lative grounds, to hope for an independent and continuing
existence of my thinking nature, throughout all possible change
of my state. In that case much will already have been gained
if, while freely confessing my own ignorance, I am yet in a
position to repel the dogmatic assaults of a speculative op-
ponent, and to show him that he can never know more of the
nature of the self in denying the possibility of my expectations
than I can know in clinging to them. 
Three other dialectical questions, constituting the real
goal of rational psychology, are grounded on this transcend-
ental illusion in our psychological concepts, and cannot be
decided except by means of the above enquiries: namely (1) of
the possibility of the communion of the soul with an organised
body, i.e. concerning animality and the state of the soul in the
life of man; (2) of the beginning of this communion, that is, of
the soul in and before birth; (3) of the end of this communion,
that is, of the soul in and after death (the question of im-
P 355
Now I maintain that all the difficulties commonly found in
these questions, and by means of which, as dogmatic objections,
men seek to gain credit for a deeper insight into the nature of
things than any to which the ordinary understanding can
properly lay claim, rest on a mere delusion by which they
hypostatise what exists merely in thought, and take it as a real
object existing, in the same character, outside the thinking sub-
ject. In other words, they regard extension, which is nothing
but appearance, as a property of outer things that subsists
even apart from our sensibility, and hold that motion is
due to these things and really occurs in and by itself, apart
from our senses. For matter, the communion of which with
the soul arouses so much questioning, is nothing but a mere
form, or a particular way of representing an unknown object
by means of that intuition which is called outer sense. There
may well be something outside us to which this appearance,
which we call matter, corresponds; in its character of appear-
ance it is not, however, outside us, but is only a thought in us,
although this thought, owing to the above-mentioned outer
sense, represents it as existing outside us. Matter, therefore,
does not mean a kind of substance quite distinct and hetero-
geneous from the object of inner sense (the soul), but only the
distinctive nature of those appearances of objects -- in them-
selves unknown to us -- the representations of which we call
outer as compared with those which we count as belonging to
inner sense, although like all other thoughts these outer repre-
sentations belong only to the thinking subject. They have,
indeed, this deceptive property that, representing objects in
space, they detach themselves as it were from the soul and
appear to hover outside it. Yet the very space in which they
are intuited is nothing but a representation, and no counter-
part of the same quality is to be found outside the soul. Con-
sequently, the question is no longer of the communion of the
soul with other known substances of a different kind outside us,
but only of the connection of the representations of inner sense
with the modifications of our outer sensibility -- as to how these
can be so connected with each other according to settled laws
that they exhibit the unity of a coherent experience. 
As long as we take inner and outer appearances together
as mere representations in experience, we find nothing absurd
P 356
and strange in the association of the two kinds of senses. But
as soon as we hypostatise outer appearances and come to re-
gard them not as representations but as things existing by them-
selves outside us, with the same quality as that with which they
exist in us, and as bringing to bear on our thinking subject the
activities which they exhibit as appearances in relation to each
other, then the efficient causes outside us assume a character
which is irreconcilable with their effects in us. For the cause re-
lates only to outer sense, the effect to inner sense -- senses which,
although combined in one subject, are extremely unlike each
other. In outer sense we find no other outer effects save changes
of place, and no forces except mere tendencies which issue in
spatial relations as their effects. Within us, on the other hand,
the effects are thoughts, among which is not to be found any
relation of place, motion, shape, or other spatial determina-
tion, and we altogether lose the thread of the causes in the
effects to which they are supposed to have given rise in inner
sense. We ought, however, to bear in mind that bodies are
not objects in themselves which are present to us, but a mere
appearance of we know not what unknown object; that motion
is not the effect of this unknown cause, but only the appearance
of its influence on our senses. Neither bodies nor motions are
anything outside us; both alike are mere representations in us;
and it is not, therefore, the motion of matter that produces re-
presentations in us; the motion itself is representation only, as
also is the matter which makes itself known in this way. Thus
in the end the whole difficulty which we have made for our-
selves comes to this, how and why the representations of our
sensibility are so interconnected that those which we entitle
outer intuitions can be represented according to empirical
laws as objects outside us -- a question which is not in any
way bound up with the supposed difficulty of explaining
the origin of our representations from quite heterogeneous
efficient causes outside us. That difficulty has arisen from
our taking the appearances of an unknown cause as being
the cause itself outside us, a view which can result in no-
thing but confusion. In the case of judgments in which a
misapprehension has taken deep root through long custom,
it is impossible at once to give to their correction that clarity
P 357
which can be achieved in other cases where no such inevitable
illusion confuses the concept. Our freeing of reason from
sophistical theories can hardly, therefore, at this stage have
the clearness which is necessary for its complete success. 
The following comments will, I think, be helpful as contri-
buting towards this ultimate clarity. 
All objections can be divided into dogmatic, critical, and
sceptical. A dogmatic objection is directed against a proposi-
tion, a critical objection against the proof of a proposition. 
The former requires an insight into the nature of the object
such that we can maintain the opposite of what the proposi-
tion has alleged in regard to this object. It is therefore itself
dogmatic, claiming acquaintance with the constitution of the
object fuller than that of the counter-assertion. A critical objec-
tion, since it leaves the validity or invalidity of the proposition
unchallenged, and assails only the proof, does not presuppose
fuller acquaintance with the object or oblige us to claim
superior knowledge of its nature; it shows only that the asser-
tion is unsupported, not that it is wrong. A sceptical objec-
tion sets assertion and counter-assertion in mutual opposition
to each other as having equal weight, treating each in turn as
dogma and the other as the objection thereto. And the con-
flict, as the being thus seemingly dogmatic on both the oppos-
ing sides, is taken as showing that all judgment in regard
to the object is completely null and void. Thus dogmatic
and sceptical objections alike lay claim to such insight into
their object as is required to assert or to deny something in
regard to it. A critical objection, on the other hand, confines
itself to pointing out that in the making of the assertion some-
thing has been presupposed that is void and merely fictitious;
and it thus overthrows the theory by removing its alleged
foundation without claiming to establish anything that
bears directly upon the constitution of the object. 
So long as we hold to the ordinary concepts of our
reason with regard to the communion in which our thinking
subject stands with the things outside us, we are dogmatic,
looking upon them as real objects existing independently of
us, in accordance with a certain transcendental dualism which
does not assign these outer appearances to the subject as
representations, but sets them, just as they are given us in
P 358
sensible intuition, as objects outside us, completely separ-
ating them from the thinking subject. This subreption is
the basis of all theories in regard to the communion between
soul and body. The objective reality thus assigned to ap-
pearances is never brought into question. On the contrary,
it is taken for granted; the theorising is merely as to the
mode in which it has to be explained and understood. There
are three usual systems devised on these lines, and they are
indeed the only possible systems: that of physical influence,
that of predetermined harmony, and that of supernatural
The two last methods of explaining the communion be-
tween the soul and matter are based on objections to the first
view, which is that of common sense. It is argued, namely, that
what appears as matter cannot by its immediate influence be
the cause of representations, these being effects which are
quite different in kind from matter. Now those who take this
line cannot attach to what they understand by 'object of outer
senses' the concept of a matter which is nothing but ap-
pearance, and so itself a mere representation produced by
some sort of outer objects. For in that case they would be say-
ing that the representations of outer objects (appearances) can-
not be outer causes of the representations in our mind; and
this would be a quite meaningless objection, since no one could
dream of holding that what he has once come to recognise as
mere representation, is an outer cause. On our principles they
can establish their theory only by showing that that which is
the true (transcendental) object of our outer senses cannot be
the cause of those representations (appearances) which we
comprehend under the title 'matter'. No one, however, can
have the right to claim that he knows anything in regard to the
transcendental cause of our representations of the outer senses;
and their assertion is therefore entirely groundless. If, on the
other hand, those who profess to improve upon the doctrine of
physical influence keep to the ordinary outlook of transcend-
ental dualism, and suppose matter, as such, to be a thing-in-
itself (not the mere appearance of an unknown thing), they will
direct their objection to showing that such an outer object,
which in itself exhibits no causality save that of movements,
can never be the efficient cause of representations, but that a
P 359
third entity must intervene to establish, if not reciprocal inter-
action, at least correspondence and harmony between the two. 
But in arguing in this way, they begin their refutation by ad-
mitting into their dualism the proton pseudos of [a doctrine of]
physical influence, and consequently their objection is not so
much a disproof of natural influence as of their own dualistic
presupposition. For the difficulties in regard to the connection
of our thinking nature with matter have their origin, one and
all, in the illicitly assumed dualistic view, that matter as such
is not appearance, that is, a mere representation of the mind
to which an unknown object corresponds, but is the object in
itself as it exists outside us independently of all sensibility. 
As against the commonly accepted doctrine of physical in-
fluence, an objection of the dogmatic type is not, therefore,
practicable. For if the opponent of the doctrine accepts the
view that matter and its motion are mere appearances and so
themselves mere representations, his difficulty is then simply
this, that it is impossible that the unknown object of our sensi-
bility should be the cause of the representations in us. He can-
not, however, have the least justification for any such conten-
tion, since no one is in a position to decide what an unknown
object may or may not be able to do. And this transcendental
idealism, as we have just proved, he cannot but concede. His
only way of escape would be frankly to hypostatise representa-
tions, and to set them outside himself as real things. 
The doctrine of physical influence, in its ordinary form,
is, however, subject to a well-founded critical objection. The
alleged communion between two kinds of substances, the
thinking and the extended, rests on a crude dualism, and
treats the extended substances, which are really nothing
but mere representations of the thinking subject, as existing
by themselves. This mistaken interpretation of physical in-
fluence can thus be effectively disposed of: we have shown
that the proof of it is void and illicit. 
The much-discussed question of the communion between
the thinking and the extended, if we leave aside all that is
merely fictitious, comes then simply to this: how in a thinking
subject outer intuition, namely, that of space, with its filling-
in of shape and motion, is possible. And this is a question
which no man can possibly answer. This gap in our knowledge
P 360
can never be filled; all that can be done is to indicate it through
the ascription of outer appearances to that transcendental ob-
ject which is the cause of this species of representations, but of
which we can have no knowledge whatsoever and of which we
shall never acquire any concept. In all problems which may
arise in the field of experience we treat these appearances as
objects in themselves, without troubling ourselves about the
primary ground of their possibility (as appearances). But to
advance beyond these limits the concept of a transcendental
object would be indispensably required. 
The settlement of all disputes or objections which concern
the state of the thinking nature prior to this communion (prior
to life), or after the cessation of such communion (in death),
rests upon these considerations regarding the communion
between thinking beings and extended beings. The opinion
that the thinking subject has been capable of thought prior to
any communion with bodies would now appear as an assertion
that, prior to the beginning of the species of sensibility in
virtue of which something appears to us in space, those tran-
scendental objects, which in our present state appear as bodies,
could have been intuited in an entirely different manner. The
opinion that the soul after the cessation of all communion with
the corporeal world could still continue to think, would be
formulated as the view that, if that species of sensibility, in
virtue of which transcendental objects, at present quite un-
known to us, appear as a material world, should cease, all in-
tuition of the transcendental objects would not for that reason
be removed, and it would still be quite possible that those same
unknown objects should continue to be known by the thinking
subject, though no longer, indeed, in the quality of bodies. 
Now on speculative principles no one can give the least
ground for any such assertion. Even the possibility of what is
asserted cannot be established; it can only be assumed. But it
is equally impossible for anyone to bring any valid dogmatic
objection against it. For whoever he may be, he knows just as
little of the absolute, inner cause of outer corporeal appear-
ances as I or anybody else. Since he cannot, therefore, offer
any justification for claiming to know on what the outer ap-
pearances in our present state (that of life) really rest,
neither can he know that the condition of all outer intui-
P 361
tion or the thinking subject itself, will cease with this state
(in death). 
Thus all controversy in regard to the nature of the thinking
being and its connection with the corporeal world is merely a re-
sult of filling the gap where knowledge is wholly lacking to us
with paralogisms of reason, treating our thoughts as things and
hypostatising them. Hence originates an imaginary science,
imaginary both in the case of him who affirms and of him
who denies, since all parties either suppose some knowledge
of objects of which no human being has any concept, or treat
their own representations as objects, and so revolve in a per-
petual circle of ambiguities and contradictions. Nothing but
the sobriety of a critique, at once strict and just, can free us from
this dogmatic delusion, which through the lure of an imagined
felicity keeps so many in bondage to theories and systems. 
Such a critique confines all our speculative claims rigidly to
the field of possible experience; and it does this not by shallow
scoffing at ever-repeated failures or pious sighs over the limits
of our reason, but by an effective determining of these limits
in accordance with established principles, inscribing its nihil
ulterius on those Pillars of Hercules which nature herself has
erected in order that the voyage of our reason may be ex-
tended no further than the continuous coastline of experience
itself reaches -- a coast we cannot leave without venturing
upon a shoreless ocean which, after alluring us with ever-
deceptive prospects, compels us in the end to abandon as
hopeless all this vexatious and tedious endeavour. 
* * *
We still owe the reader a clear general exposition of the
transcendental and yet natural illusion in the paralogisms of
pure reason, and also a justification of the systematic ordering
of them which runs parallel with the table of the categories. 
We could not have attempted to do so at the beginning of this
section without running the risk of becoming obscure or of
clumsily anticipating the course of our argument. We shall
now try to fulfil this obligation. 
All illusion may be said to consist in treating the subjective
condition of thinking as being knowledge of the object. Further
in the Introduction to the Transcendental Dialectic we have
P 362
shown that pure reason concerns itself solely with the totality
of the synthesis of the conditions, for a given conditioned. Now
since the dialectical illusion of pure reason cannot be an em-
pirical illusion, such as occurs in certain specific instances of
empirical knowledge, it will relate to what is universal in the
conditions of thinking, and there will therefore be only three
cases of the dialectical employment of pure reason. 
1. The synthesis of the conditions of a thought in general. 
2. The synthesis of the conditions of empirical thinking. 
3. The synthesis of the conditions of pure thinking. 
In all these three cases pure reason occupies itself only
with the absolute totality of this synthesis, that is, with that
condition which is itself unconditioned. On this division is
founded the threefold transcendental illusion which gives
occasion for the three main sections of the Dialectic, and for
the three pretended sciences of pure reason -- transcendental
psychology, cosmology, and theology. Here we are concerned
only with the first. 
Since, in thinking in general, we abstract from all relation
of the thought to any object (whether of the senses or of the
pure understanding), the synthesis of the conditions of a
thought in general (No. 1) is not objective at all, but merely a
synthesis of the thought with the subject, which is mistaken
for a synthetic representation of an object. 
It follows from this that the dialectical inference to the
condition of all thought in general, which is itself uncon-
ditioned, does not commit a material error (for it abstracts
from all content or objects), but is defective in form alone, and
must therefore be called a paralogism. 
Further, since the one condition which accompanies all
thought is the 'I' in the universal proposition 'I think',
reason has to deal with this condition in so far as it is itself
unconditioned. It is only the formal condition, namely, the
logical unity of every thought, in which I abstract from all
objects; but nevertheless it is represented as an object which I
think, namely, I myself and its unconditioned unity. 
If anyone propounds to me the question, 'What is the con-
P 363
stitution of a thing which thinks? ', I have no a priori know-
ledge wherewith to reply. For the answer has to be synthetic --
an analytic answer will perhaps explain what is meant by
thought, but beyond this cannot yield any knowledge of that
upon which this thought depends for its possibility. For a
synthetic solution, however, intuition is always required; and
owing to the highly general character of the problem, intuition
has been left entirely out of account. Similarly no one can answer
in all its generality the question, 'What must a thing be, to be
movable? ' For the question contains no trace of the answer,
viz. impenetrable extension (matter). But although I have no
general answer to the former question, it still seems as if I
could reply in the special case of the proposition which ex-
presses self-consciousness -- 'I think'. For this 'I' is the primary
subject, that is, substance; it is simple, etc. But these would
then have to be propositions derived from experience, and in
the absence of a universal rule which expresses the conditions
of the possibility of thought in general and a priori, they could
not contain any such non-empirical predicates. Suspicion is
thus thrown on the view, which at first seemed to me so
plausible, that we can form judgments about the nature of a
thinking being, and can do so from concepts alone. But the
error in this way of thinking has not yet been detected. 
Further investigation into the origin of the attributes which
I ascribe to myself as a thinking being in general can, however,
show in what the error consists. These attributes are nothing
but pure categories, by which I do not think a determinate ob-
ject but only the unity of the representations -- in order to deter-
mine an object for them. In the absence of an underlying intui-
tion the category cannot by itself yield a concept of an object; for
by intuition alone is the object given, which thereupon is thought
in accordance with the category. If I am to declare a thing to
be a substance in the [field of] appearance, predicates of its in-
tuition must first be given me, and I must be able to distinguish
in these the permanent from the transitory and the substratum
(the thing itself) from what is merely inherent in it. If I call a
thing in the [field of] appearance simple, I mean by this that
the intuition of it, although a part of the appearance, is not
P 364
itself capable of being divided into parts, etc. But if I know
something as simple in concept only and not in the [field of]
appearance, I have really no knowledge whatsoever of the
object, but only of the concept which I make for myself of a
something in general that does not allow of being intuited. I
say that I think something as completely simple, only because
I have really nothing more to say of it than merely that it is
Now the bare apperception, 'I', is in concept substance, in
concept simple, etc. ; and in this sense all those psychological
doctrines are unquestionably true. Yet this does not give us
that knowledge of the soul for which we are seeking. For since
none of these predicates are valid of intuition, they cannot
have any consequences which are applicable to objects of
experience, and are therefore entirely void. The concept of
substance does not teach me that the soul endures by itself,
nor that it is a part of outer intuitions which cannot itself be
divided into parts, and cannot therefore arise or perish by any
natural alterations. These are properties which would make
the soul known to me in the context of experience and might
reveal something concerning its origin and future state. But
if I say, in terms of the mere category, 'The soul is a simple
substance', it is obvious that since the bare concept of sub-
stance (supplied by the understanding) contains nothing be-
yond the requirement that a thing be represented as being
subject in itself, and not in turn predicate of anything else,
nothing follows from this as regards the permanence of the
'I', and the attribute 'simple' certainly does not aid in adding
this permanence. Thus, from this source, we learn nothing
whatsoever as to what may happen to the soul in the changes
of the natural world. If we could be assured that the soul is a
simple part of matter, we could use this knowledge, with the
further assistance of what experience teaches in this regard, to
deduce the permanence, and, as involved in its simple nature,
the indestructibility of the soul. But of all this, the concept
of the 'I', in the psychological principle 'I think', tells us
That the being which thinks in us is under the impression
that it knows itself through pure categories, and precisely
P 365
through those categories which in each type of category
express absolute unity, is due to the following reason. Apper-
ception is itself the ground of the possibility of the categories,
which on their part represent nothing but the synthesis of the
manifold of intuition, in so far as the manifold has unity in
apperception. Self-consciousness in general is therefore the
representation of that which is the condition of all unity, and
itself is unconditioned. We can thus say of the thinking 'I'
(the soul) which regards itself as substance, as simple, as
numerically identical at all times, and as the correlate of all
existence, from which all other existence must be inferred,
that it does not know itself through the categories, but knows
the categories, and through them all objects, in the absolute
unity of apperception, and so through itself. Now it is, in-
deed, very evident that I cannot know as an object that which
I must presuppose in order to know any object, and that the
determining self (the thought) is distinguished from the self
that is to be determined (the thinking subject) in the same
way as knowledge is distinguished from its object. Neverthe-
less there is nothing more natural and more misleading than
the illusion which leads us to regard the unity in the synthesis
of thoughts as a perceived unity in the subject of these thoughts. 
We might call it the subreption of the hypostatised conscious-
ness (apperceptionis substantiatae). 
If we desire to give a logical title to the paralogism con-
tained in the dialectical syllogisms of the rational doctrine of
the soul, then in view of the fact that their premisses are cor-
rect, we may call it a sophisma figurae dictionis. Whereas the
major premiss, in dealing with the condition, makes a merely
transcendental use of the category, the minor premiss and the
conclusion, in dealing with the soul which has been subsumed
under this condition, use the same category empirically. Thus,
for instance, in the paralogism of substantiality, the con-
cept of substance is a pure intellectual concept, which in the
absence of the conditions of sensible intuition admits only of
transcendental use, that is, admits of no use whatsoever. But in
the minor premiss the very same concept is applied to the object
P 366
of all inner experience without our having first ascertained
and established the condition of such employment in concreto,
namely, the permanence of this object. We are thus making an
empirical, but in this case inadmissible, employment of the
Finally, in order to show the systematic interconnection of
all these dialectical assertions of a pseudo-rational doctrine of
the soul in an order determined by pure reason, and so to show
that we have them in their completeness, we may note that
apperception has been carried through all the classes of the
categories but only in reference to those concepts of under-
standing which in each class form the basis of the unity of the
others in a possible perception, namely, subsistence, reality,
unity (not plurality), and existence. Reason here represents all
of these as conditions, which are themselves unconditioned, of
the possibility of a thinking being. Thus the soul knows in
itself --
(1) the unconditioned unity of relation, i.e. that it itself is not
inherent [in something else] but self-subsistent. 
(2) the unconditioned unity of quality, that is, that it is not a
real whole but simple. 
(3) the unconditioned unity in the plurality in time, i.e. that
it is not numerically different at different times but one
and the very same subject. 
(4) the unconditioned unity of existence in space, i.e. that it
is not the consciousness of many things outside it, but
the consciousness of the existence of itself only, and of
other things merely as its representations. 
 Reason is the faculty of principles. The assertions of pure
psychology do not contain empirical predicates of the soul but
those predicates, if there be any such, which are meant to de-
termine the object in itself independently of experience, and
so by mere reason. They ought, therefore, to be founded on
principles and universal concepts bearing on the nature of thinking beings in ge
++ How the simple here again corresponds to the category of
reality I am not yet in a position to explain. This will be shown in
the next chapter on the occasion of this same concept being put by
reason to yet another use. 
P 367
But instead we find that the single
representation, 'I am', governs them all. This representation
just because it expresses the pure formula of all my experience
in general announces itself as a universal proposition valid
for all thinking beings; and since it is at the same time in all
respects unitary, it carries with it the illusion of an absolute
unity of the conditions of thought in general, and so extends
itself further than possible experience can reach. 
P 368
SINCE the proposition 'I think' (taken problematically) con-
tains the form of each and every judgment of understanding
and accompanies all categories as their vehicle, it is evident
that the inferences from it admit only of a transcendental em-
ployment of the understanding. And since this employment
excludes any admixture of experience, we cannot, after what
has been shown above, entertain any favourable anticipations
in regard to its methods of procedure. We therefore propose to
follow it, with a critical eye, through all the predicaments of
pure psychology. But for the sake of brevity the examination
had best proceed in an unbroken continuity. 
The following general remark may, at the outset, aid us in
our scrutiny of this kind of argument. I do not know an object
merely in that I think, but only in so far as I determine a given
intuition with respect to the unity of consciousness in which all
thought consists. Consequently, I do not know myself through
being conscious of myself as thinking, but only when I am con-
scious of the intuition of myself as determined with respect
to the function of thought. Modi of self-consciousness in
thought are not by themselves concepts of objects (categories),
but are mere functions which do not give thought an object
to be known, and accordingly do not give even myself as
object. The object is not the consciousness of the determining
self, but only that of the determinable self, that is, of my
inner intuition (in so far as its manifold can be combined in
accordance with the universal condition of the unity of apper-
ception in thought). 
P 369
(1) In all judgments I am the determining subject of that
relation which constitutes the judgment. That the 'I', the 'I'
that thinks, can be regarded always as subject, and as something
which does not belong to thought as a mere predicate, must be
granted. It is an apodeictic and indeed identical proposition;
but it does not mean that I, as object, am for myself a self-
subsistent being or substance. The latter statement goes very far
beyond the former, and demands for its proof data which are
not to be met with in thought, and perhaps (in so far as I have
regard to the thinking self merely as such) are more than I
shall ever find in it. 
(2) That the 'I' of apperception, and therefore the 'I' in
every act of thought, is one, and cannot be resolved into a
plurality of subjects, and consequently signifies a logically
simple subject, is something already contained in the very
concept of thought, and is therefore an analytic proposition. 
But this does not mean that the thinking 'I' is a simple sub-
stance. That proposition would be synthetic. The concept of
substance always relates to intuitions which cannot in me be
other than sensible, and which therefore lie entirely outside
the field of the understanding and its thought. But it is of
this thought that we are speaking when we say that the 'I' in
thought is simple. It would, indeed, be surprising if what in
other cases requires so much labour to determine -- namely,
what, of all that is presented in intuition, is substance, and
further, whether this substance can be simple (e.g. in the
parts of matter) -- should be thus given me directly, as if by
revelation, in the poorest of all representations. 
(3) The proposition, that in all the manifold of which I am
conscious I am identical with myself, is likewise implied in the
concepts themselves, and is therefore an analytic proposition. 
But this identity of the subject, of which I can be conscious in
all my representations, does not concern any intuition of the
subject, whereby it is given as object, and cannot therefore
signify the identity of the person, if by that is understood the
consciousness of the identity of one's own substance, as a
thinking being, in all change of its states. No mere analysis of
the proposition 'I think' will suffice to prove such a proposi-
P 370
tion; for that we should require various synthetic judgments,
based upon given intuition. 
(4) That I distinguish my own existence as that of a
thinking being, from other things outside me--among them
my body -- is likewise an analytic proposition; for other things
are such as I think to be distinct from myself. But I do not
thereby learn whether this consciousness of myself would be
even possible apart from things outside me through which
representations are given to me, and whether, therefore, I
could exist merely as thinking being (i.e. without existing in
human form). 
The analysis, then, of the consciousness of myself in
thought in general, yields nothing whatsoever towards the
knowledge of myself as object. The logical exposition of
thought in general has been mistaken for a metaphysical
determination of the object. 
Indeed, it would be a great stumbling-block, or rather
would be the one unanswerable objection, to our whole cri-
tique, if there were a possibility of proving a priori that all
thinking beings are in themselves simple substances, and that
consequently (as follows from this same mode of proof) per-
sonality is inseparable from them, and that they are conscious
of their existence as separate and distinct from all matter. 
For by such procedure we should have taken a step beyond
the world of sense, and have entered into the field of noumena;
and no one could then deny our right of advancing yet further
in this domain, indeed of settling in it, and, should our star
prove auspicious, of establishing claims to permanent posses-
sion. The proposition, 'Every thinking being is, as such, a
simple substance', is a synthetic a priori proposition; it is syn-
thetic in that it goes beyond the concept from which it starts,
and adds to the thought in general [i.e. to the concept of
a thinking being] the mode of [its] existence: it is a priori,
in that it adds to the concept a predicate (that of simplicity)
which cannot be given in any experience. It would then follow
that a priori synthetic propositions are possible and admis-
sible, not only, as we have asserted, in relation to objects of
possible experience, and indeed as principles of the possibility
of this experience, but that they are applicable to things in
general and to things in themselves -- a result that would make
P 371
an end of our whole critique, and would constrain us to ac-
quiesce in the old-time procedure. Upon closer consideration
we find, however, that there is no such serious danger. 
The whole procedure of rational psychology is determined
by a paralogism, which is exhibited in the following syllogism:
That which cannot be thought otherwise than as subject
does not exist otherwise than as subject, and is therefore
A thinking being, considered merely as such, cannot be
thought otherwise than as subject. 
Therefore it exists also only as subject, that is, as substance. 
In the major premiss we speak of a being that can be
thought in general, in every relation, and therefore also as it
may be given in intuition. But in the minor premiss we speak
of it only in so far as it regards itself, as subject, simply in
relation to thought and the unity of consciousness, and not as
likewise in relation to the intuition through which it is given
as object to thought. Thus the conclusion is arrived at fallaci-
ously, per sophisma figurae dictionis. 
That we are entirely right in resolving this famous argu-
ment into a paralogism will be clearly seen, if we call to mind
what has been said in the General Note to the Systematic
Representation of the Principles and in the Section on Nou-
++ 'Thought' is taken in the two premisses in totally different
senses: in the major premiss, as relating to an object in general and
therefore to an object as it may be given in intuition; in the minor
premiss, only as it consists in relation to self-consciousness. In
this latter sense, no object whatsoever is being thought; all that is
being represented is simply the relation to self as subject (as the
form of thought). In the former premiss we are speaking of things
which cannot be thought otherwise than as subjects; but in the latter
premiss we speak not of things but of thought (abstraction being
made from all objects) in which the 'I' always serves as the subject
of consciousness. The conclusion cannot, therefore, be, 'I cannot
exist otherwise than as subject', but merely, 'In thinking my exist-
ence, I cannot employ myself, save as subject of the judgment
[therein involved]'. This is an identical proposition, and casts no
light whatsoever upon the mode of my existence. 
P 371
For it has there been proved that the concept of a thing
P 372
which can exist by itself as subject and never as mere predi-
cate, carries with it no objective reality; in other words, that we
cannot know whether there is any object to which the concept
is applicable -- as to the possibility of such a mode of existence
we have no means of deciding -- and that the concept therefore
yields no knowledge whatsoever. If by the term 'substance' be
meant an object which can be given, and if it is to yield know-
ledge, it must be made to rest on a permanent intuition, as
being that through which alone the object of our concept can
be given, and as being, therefore, the indispensable condition
of the objective reality of the concept. Now in inner intuition
there is nothing permanent, for the 'I' is merely the conscious-
ness of my thought. So long, therefore, as we do not go beyond
mere thinking, we are without the necessary condition for
applying the concept of substance, that is, of a self-subsistent
subject, to the self as a thinking being. And with the objective
reality of the concept of substance, the allied concept of
simplicity likewise vanishes; it is transformed into a merely
logical qualitative unity of self-consciousness in thought in
general, which has to be present whether the subject be com-
posite or not. 
This acute philosopher soon noticed that the usual argu-
ment by which it is sought to prove that the soul -- if it be
admitted to be a simple being -- cannot cease to be through
dissolution, is insufficient for its purpose, that of proving the
necessary continuance of the soul, since it may be supposed
to pass out of existence through simply vanishing. In his
Phaedo he endeavoured to prove that the soul cannot be
subject to such a process of vanishing, which would be a
true annihilation, by showing that a simple being cannot
cease to exist. His argument is that since the soul cannot
be diminished, and so gradually lose something of its exist-
ence, being by degrees changed into nothing (for since it
has no parts, it has no multiplicity in itself), there would be
P 373
no time between a moment in which it is and another in which
it is not -- which is impossible. He failed, however, to observe
that even if we admit the simple nature of the soul, namely,
that it contains no manifold of constituents external to one
another, and therefore no extensive quantity, we yet cannot
deny to it, any more than to any other existence, intensive
quantity, that is, a degree of reality in respect of all its facul-
ties, nay, in respect of all that constitutes its existence, and
that this degree of reality may diminish through all the in-
finitely many smaller degrees. In this manner the supposed
substance -- the thing, the permanence of which has not yet
been proved -- may be changed into nothing, not indeed by
dissolution, but by gradual loss (remissio) of its powers, and
so, if I may be permitted the use of the term, by elanguescence. 
For consciousness itself has always a degree, which always
allows of diminution, and the same must also hold of the
faculty of being conscious of the self, and likewise of all the
other faculties. Thus the permanence of the soul, regarded
merely as object of inner sense, remains undemonstrated, and
indeed indemonstrable. Its permanence during life is, of course,
evident per se, since the thinking being (as man) is itself like-
wise an object of the outer senses. But this is very far from
satisfying the rational psychologist who undertakes to prove
from mere concepts its absolute permanence beyond this life. 
++ Clearness is not, as the logicians assert, the consciousness of
a representation. A certain degree of consciousness, though it be
insufficient for recollection, must be met with even in many obscure
representations, since in the absence of all consciousness we should
make no distinction between different combinations of obscure repre-
sentations, which yet we are able to do in respect of the characters
of many concepts, such as those of right or equity, or as when the
musician in improvising strikes several keys at once. But a repre-
sentation is clear, when the consciousness suffices for the conscious-
ness of the distinction of this representation from others. If it suffices
for distinguishing, but not for consciousness of the distinction, the
representation must still be entitled obscure. There are therefore
infinitely many degrees of consciousness, down to its complete
++ Some philosophers, in making out a case for a new possibility,
consider that they have done enough if they can defy others to show
any contradiction in their assumptions. 
P 374
 If we take the above propositions in synthetic connec-
tion, as valid for all thinking beings, as indeed they must
be taken in the system of rational psychology, and proceed
from the category of relation, with the proposition, 'All think-
ing beings are, as such, substances', backwards through the
series of the propositions, until the circle is completed, we
P 375
come at last to the existence of these thinking beings. 
P 374n
++This is the procedure of all
those who profess to comprehend the possibility of thought -- of
which they have an example only in the empirical intuitions of our
human life -- even after this life has ceased. But those who resort to
such a method of argument can be quite nonplussed by the citation
of other possibilities which are not a whit more adventurous. Such
is the possibility of the division of a simple substance into several
substances, and conversely the fusing together (coalition) of several
into one simple substance. For although divisibility presupposes a
composite, it does not necessarily require a composite of substances,
but only of degrees (of the manifold powers) of one and the same sub-
stance. Now just as we can think all powers and faculties of the soul,
even that of consciousness, as diminished by one half, but in such a
way that the substance still remains, so also, without contradiction,
we can represent this extinguished half as being preserved, not in
the soul, but outside it; and we can likewise hold that since every-
thing which is real in it, and which therefore has a degree -- in other
words, its entire existence, from which nothing is lacking -- has been
halved, another separate substance would then come into existence
outside it. For the multiplicity which has been divided existed
before, not indeed as a multiplicity of substances, but as the multi-
plicity of every reality proper to the substance, that is, of the quan-
tum of existence in it; and the unity of substance was therefore only
a mode of existence, which in virtue of this division has been trans-
formed into a plurality of subsistence. Similarly, several simple sub-
stances might be fused into one, without anything being lost except
only the plurality of subsistence, inasmuch as the one substance
would contain the degree of reality of all the former substances to-
gether. We might perhaps also represent the simple substances which
yield us the appearance [which we entitle] matter as producing -- not
indeed by a mechanical or chemical influence upon one another, but
by an influence unknown to us, of which the former influence would
be merely the appearance -- the souls of children, that is, as pro-
ducing them through such dynamical division of the parent souls,
considered as intensive quantities, and those parent souls as making
good their loss through coalition with new material of the same kind. 
P 375
Now in
this system of rational psychology these beings are taken not
only as being conscious of their existence independently of
outer things, but as also being able, in and by themselves, to
determine that existence in respect of the permanence which
is a necessary characteristic of substance. This rationalist sys-
tem is thus unavoidably committed to idealism, or at least to
problematic idealism. For if the existence of outer things is
not in any way required for determination of one's own
existence in time, the assumption of their existence is a
quite gratuitous assumption, of which no proof can ever be
If, on the other hand, we should proceed analytically,
starting from the proposition 'I think', as a proposition that
already in itself includes an existence as given, and therefore
modality, and analysing it in order to ascertain its content,
and so to discover whether and how this 'I' determines its
existence in space or time solely through that content, then
the propositions of the rational doctrine of the soul would not
begin with the concept of a thinking being in general, but with
a reality, and we should infer from the manner in which this
reality is thought, after everything empirical in it has been
removed, what it is that belongs to a thinking being in general. 
This is shown in the following table: 
++ I am far from allowing any serviceableness or validity to such fancies;
and as the principles of our Analytic have sufficiently demonstrated,
no other than an empirical employment of the categories (including
that of substance) is possible. But if the rationalist is bold enough,
out of the mere faculty of thought, without any permanent intuition
whereby an object might be given, to construct a self-subsistent being,
and this merely on the ground that the unity of apperception in thought
does not allow of its being explained [as arising] out of the composite,
instead of admitting, as he ought to do, that he is unable to explain
the possibility of a thinking nature, why should not the materialist,
though he can as little appeal to experience in support of his [con-
jectured] possibilities, be justified in being equally daring, and in
using his principle to establish the opposite conclusion, while still
preserving the formal unity upon which his opponent has relied. 
P 376
1. I think,
2. as subject, 3. as simple subject,
4. as identical subject
in every state of my thought. 
In the second proposition it has not been determined
whether I can exist and be thought as subject only, and not
also as a predicate of another being, and accordingly the con-
cept of a subject is here taken in a merely logical sense, and it
remains undetermined whether or not we are to understand
by it a substance. Similarly, the third proposition establishes
nothing in regard to the constitution or subsistence of the sub-
ject; none the less in this proposition the absolute unity of apper-
ception, the simple 'I' in the representation to which all com-
bination or separation that constitutes thought relates, has its
own importance. For apperception is something real, and its
simplicity is already given in the mere fact of its possibility. 
Now in space there is nothing real which can be simple; points,
which are the only simple things in space, are merely limits
not themselves anything that can as parts serve to constitute
space. From this follows the impossibility of any explana-
tion in materialist terms of the constitution of the self as a
merely thinking subject. But since my existence is taken in
the first proposition as given -- for it does not say that every
thinking being exists, which would be to assert its absolute
necessity and therefore to say too much, but only, 'I exist
thinking' -- the proposition is empirical, and can determine
my existence only in relation to my representations in time. 
But since for this purpose I again require something perma-
nent, which, so far as I think myself, is in no way given to me
in inner intuition, it is quite impossible, by means of this simple
self-consciousness, to determine the manner in which I exist,
whether it be as substance or as accident. Thus, if materialism
is disqualified from explaining my existence, spiritualism is
equally incapable of doing so; and the conclusion is that in no
way whatsoever can we know anything of the constitution of
the soul, so far as the possibility of its separate existence is
How, indeed, should it be possible, by means of the unity
P 377
of consciousness -- which we only know because we cannot
but make use of it, as indispensable for the possibility of
experience -- to pass out beyond experience (our existence in
this life), and even to extend our knowledge to the nature of
all thinking beings in general, through the empirical, but in
respect of every sort of intuition the quite indeterminate pro-
position, 'I think'? 
Rational psychology exists not as doctrine, furnishing an
addition to our knowledge of the self, but only as discipline. 
It sets impassable limits to speculative reason in this field, and
thus keeps us, on the one hand, from throwing ourselves into
the arms of a soulless materialism, or, on the other hand, from
losing ourselves in a spiritualism which must be quite un-
founded so long as we remain in this present life. But though
it furnishes no positive doctrine, it reminds us that we should
regard this refusal of reason to give satisfying response to our
inquisitive probings into what is beyond the limits of this
present life as reason's hint to divert our self-knowledge from
fruitless and extravagant speculation to fruitful practical em-
ployment. Though in such practical employment it is directed
always to objects of experience only, it derives its principles
from a higher source, and determines us to regulate our actions
as if our destiny reached infinitely far beyond experience, and
therefore far beyond this present life. 
From all this it is evident that rational psychology owes
its origin simply to misunderstanding. The unity of conscious-
ness, which underlies the categories, is here mistaken for an
intuition of the subject as object, and the category of sub-
stance is then applied to it. But this unity is only unity in
thought, by which alone no object is given, and to which,
therefore, the category of substance, which always presup-
poses a given intuition, cannot be applied. Consequently, this
subject cannot be known. The subject of the categories cannot
by thinking the categories acquire a concept of itself as an
object of the categories. For in order to think them, its pure
self-consciousness, which is what was to be explained, must
itself be presupposed. Similarly, the subject, in which the re-
presentation of time has its original ground, cannot thereby
determine its own existence in time. And if this latter is im-
possible, the former, as a determination of the self (as a
P 378
thinking being in general) by means of the categories is
equally so. 
 Thus the expectation of obtaining knowledge which while
extending beyond the limits of possible experience is like-
wise to further the highest interests of humanity, is found,
so far as speculative philosophy professes to satisfy it, to
be grounded in deception, and to destroy itself in the attempt
at fulfilment. Yet the severity of our criticism has rendered
reason a not unimportant service in proving the impossibility
of dogmatically determining, in regard to an object of experi-
ence, anything that lies beyond the limits of experience. For in
so doing it has secured reason against all possible assertions of
the opposite. That cannot be achieved save in one or other of two ways. 
++ The 'I think' is, as already stated, an empirical proposition,
and contains within itself the proposition 'I exist'. But I cannot say
'Everything which thinks, exists'. For in that case the property of
thought would render all beings which possess it necessary beings. 
My existence cannot, therefore, be regarded as an inference from
the proposition 'I think', as Descartes sought to contend -- for it
would then have to be preceded by the major premiss 'Everything
which thinks, exists' -- but is identical with it. The 'I think' ex-
presses an indeterminate empirical intuition, i.e. perception (and
thus shows that sensation, which as such belongs to sensibility, lies
at the basis of this existential proposition) But the 'I think'
precedes the experience which is required to determine the object
of perception through the category in respect of time; and the
existence here [referred to] is not a category. The category as
such does not apply to an indeterminately given object but only to
one of which we have a concept and about which we seek to know
whether it does or does not exist outside the concept. An indetermin-
ate perception here signifies only something real that is given, given
indeed to thought in general, and so not as appearance, nor as thing
in itself (noumenon), but as something which actually exists, and
which in the proposition, 'I think', is denoted as such. For it must
be observed, that when I have called the proposition, 'I think', an
empirical proposition, I do not mean to say thereby, that the 'I' in
this proposition is an empirical representation. On the contrary,
it is purely intellectual, because belonging to thought in general. 
Without some empirical representation to supply the material for
thought, the actus, 'I think', would not, indeed, take place; but the
empirical is only the condition of the application, or of the employ-
ment, of the pure intellectual faculty. 
P 379
Either we have to prove our proposition apo-
deictically; or, if we do not succeed in this, we have to seek out
the sources of this inability, which, if they are traceable to the
necessary limits of our reason, must constrain all opponents
to submit to this same law of renunciation in respect of all
claims to dogmatic assertion. 
Yet nothing is thereby lost as regards the right, nay, the
necessity, of postulating a future life in accordance with the
principles of the practical employment of reason, which is
closely bound up with its speculative employment. For the
merely speculative proof has never been able to exercise any
influence upon the common reason of men. It so stands upon
the point of a hair, that even the schools preserve it from fall-
ing only so long as they keep it unceasingly spinning round
like a top; even in their own eyes it yields no abiding founda-
tion upon which anything could be built. The proofs which are
serviceable for the world at large all preserve their entire value
undiminished, and indeed, upon the surrender of these dog-
matic pretensions, gain in clearness and in natural force. For
reason is then located in its own peculiar sphere, namely, the
order of ends, which is also at the same time an order of nature;
and since it is in itself not only a theoretical but also a practical
faculty, and as such is not bound down to natural conditions,
it is justified in extending the order of ends, and therewith our
own existence, beyond the limits of experience and of life. If
we judged according to analogy with the nature of living
beings in this world, in dealing with which reason must
necessarily accept the principle that no organ, no faculty, no
impulse, indeed nothing whatsoever is either superfluous or
disproportioned to its use, and that therefore nothing is pur-
poseless, but everything exactly conformed to its destiny in
life -- if we judged by such an analogy we should have to re-
gard man, who alone can contain in himself the final end of
all this order, as the only creature that is excepted from it. 
Man's natural endowments -- not merely his talents and the
impulses to enjoy them, but above all else the moral law within
him -- go so far beyond all the utility and advantage which he
may derive from them in this present life, that he learns there-
by to prize the mere consciousness of a righteous will as being,
apart from all advantageous consequences, apart even from the
P 380
shadowy reward of posthumous fame, supreme over all other
values; and so feels an inner call to fit himself, by his conduct
in this world, and by the sacrifice of many of its advantages,
for citizenship in a better world upon which he lays hold in
idea. This powerful and incontrovertible proof is reinforced
by our ever-increasing knowledge of purposiveness in all that
we see around us, and by contemplation of the immensity of
creation, and therefore also by the consciousness of a certain
illimitableness in the possible extension of our knowledge, and
of a striving commensurate therewith. All this still remains to
us, but we must renounce the hope of comprehending, from
the merely theoretical knowledge of ourselves, the necessary
continuance of our existence. 
The dialectical illusion in rational psychology arises from
the confusion of an idea of reason -- the idea of a pure intelli-
gence -- with the completely undetermined concept of a think-
ing being in general. I think myself on behalf of a possible
experience, at the same time abstracting from all actual ex-
perience; and I conclude therefrom that I can be conscious of
my existence even apart from experience and its empirical
conditions. In so doing I am confusing the possible abstrac-
tion from my empirically determined existence with the sup-
posed consciousness of a possible separate existence of my
thinking self, and I thus come to believe that I have knowledge
that what is substantial in me is the transcendental subject. 
But all that I really have in thought is simply the unity of con-
sciousness, on which, as the mere form of knowledge, all
determination is based. 
The task of explaining the communion of the soul with
the body does not properly belong to the psychology with
which we are here dealing. For this psychology proposes to
prove the personality of the soul even apart from this com-
munion (that is, after death), and is therefore transcendent in
the proper sense of that term. It does, indeed, occupy itself
with an object of experience, but only in that aspect in which
P 381
it ceases to be an object of experience. Our teaching, on the
other hand, does supply a sufficient answer to this question. 
The difficulty peculiar to the problem consists, as is generally
recognised, in the assumed heterogeneity of the object of inner
sense (the soul) and the objects of the outer senses, the formal
condition of their intuition being, in the case of the former, time
only, and in the case of the latter, also space. But if we consider
that the two kinds of objects thus differ from each other, not in-
wardly but only in so far as one appears outwardly to the other,
and that what, as thing in itself, underlies the appearance of
matter, perhaps after all may not be so heterogeneous in
character, this difficulty vanishes, the only question that re-
mains being how in general a communion of substances is
possible. This, however, is a question which lies outside the
field of psychology, and which the reader, after what has been
said in the Analytic regarding fundamental powers and facul-
ties, will not hesitate to regard as likewise lying outside the
field of all human knowledge. 
The proposition, 'I think' or 'I exist thinking', is an em-
pirical proposition. Such a proposition, however, is conditioned
by empirical intuition, and is therefore also conditioned by the
object [that is, the self] which is thought [in its aspect] as
appearance. It would consequently seem that on our theory
the soul, even in thought, is completely transformed into
appearance, and that in this way our consciousness itself, as
being a mere illusion, must refer in fact to nothing. 
Thought, taken by itself, is merely the logical function,
and therefore the pure spontaneity of the combination of the
manifold of a merely possible intuition, and does not exhibit
the subject of consciousness as appearance; and this for the
sufficient reason that thought takes no account whatsoever of
the mode of intuition, whether it be sensible or intellectual. I
thereby represent myself to myself neither as I am nor as I
appear to myself. I think myself only as I do any object in
general from whose mode of intuition I abstract. If I here re-
P 382
present myself as subject of thoughts or as ground of thought,
these modes of representation do not signify the categories of
substance or of cause. For the categories are those functions
of thought (of judgment) as already applied to our sensible in-
tuition, such intuition being required if I seek to know myself. 
If, on the other hand, I would be conscious of myself simply as
thinking, then since I am not considering how my own self
may be given in intuition, the self may be mere appearance to
me, the 'I' that thinks, but is no mere appearance in so far as
I think; in the consciousness of myself in mere thought I am
the being itself, although nothing in myself is thereby given
for thought. 
The proposition, 'I think', in so far as it amounts to the
assertion, 'I exist thinking', is no mere logical function, but
determines the subject (which is then at the same time object)
in respect of existence, and cannot take place without inner
sense, the intuition of which presents the object not as thing in
itself but merely as appearance. There is here, therefore, not
simply spontaneity of thought, but also receptivity of intui-
tion, that is, the thought of myself applied to the empirical
intuition of myself. Now it is to this intuition that the thinking
self would have to look for the conditions of the employment
of its logical functions as categories of substance, cause, etc. ,
if it is not merely to distinguish itself as object in itself, through
the 'I', but is also to determine the mode of its existence, that
is, to know itself as noumenon. This, however, is impossible,
since the inner empirical intuition is sensible and yields only
data of appearance, which furnish nothing to the object of
pure consciousness for the knowledge of its separate existence,
but can serve only for the obtaining of experience. 
Should it be granted that we may in due course discover,
not in experience but in certain laws of the pure employment
of reason -- laws which are not merely logical rules, but which
while holding a priori also concern our existence -- ground for
regarding ourselves as legislating completely a priori in re-
gard to our own existence, and as determining this existence,
there would thereby be revealed a spontaneity through which
our reality would be determinable, independently of the con-
ditions of empirical intuition. And we should also become
P 383
aware that in the consciousness of our existence there is con-
tained a something a priori, which can serve to determine our
existence -- the complete determination of which is possible
only in sensible terms -- as being related, in respect of a certain
inner faculty, to a non-sensible intelligible world. 
But this would not be of the least service in furthering
the attempts of rational psychology. In this marvellous faculty,
which the consciousness of the moral law first reveals to me, I
should indeed have, for the determination of my existence, a
principle which is purely intellectual. But through what predi-
cates would that determination have to be made? They could
be no other than those which must be given to me in sensible
intuition; and thus I should find myself, as regards rational
psychology, in precisely the same position as before, namely,
still in need of sensible intuitions to confer meaning on my
concepts of understanding (substance, cause, etc. ), through
which alone I can have knowledge of myself; and these in-
tuitions can never aid me in advancing beyond the field of
experience. Nevertheless, in respect of the practical employ-
ment, which is always directed to objects of experience, I
should be justified in applying these concepts, in conformity
with their analogical meaning when employed theoretically,
to freedom and the subject that is possessed of freedom. In so
doing, however, I should understand by these concepts the
merely logical functions of subject and predicate, of ground
and consequence, in accordance with which the acts or effects
are so determined conformably to those [moral] laws, that
they always allow of being explained, together with the laws
of nature, in accordance with the categories of substance and
cause, although they have their source in an entirely different
principle. These observations are designed merely to prevent
a misunderstanding to which the doctrine of our self-intuition,
as appearance, is particularly liable. We shall have occasion
to make further application of them in the sequel.