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The Critique of Pure Reason by Immanuel Kant

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function for constructing a conception from certain data. Now,
object cannot be given to a conception otherwise than by intuition,
and, even if a pure intuition antecedent to the object is a priori
possible, this pure intuition can itself obtain objective validity
only from empirical intuition, of which it is itself but the form.
All conceptions, therefore, and with them all principles, however high
the degree of their a priori possibility, relate to empirical
intuitions, that is, to data towards a possible experience. Without
this they possess no objective validity, but are mere play of
imagination or of understanding with images or notions. Let us take,
for example, the conceptions of mathematics, and first in its pure
intuitions. "Space has three dimensions"--"Between two points there
can be only one straight line," etc. Although all these principles,
and the representation of the object with which this science
occupies itself, are generated in the mind entirely a priori, they
would nevertheless have no significance if we were not always able
to exhibit their significance in and by means of phenomena
(empirical objects). Hence it is requisite that an abstract conception
be made sensuous, that is, that an object corresponding to it in
intuition be forthcoming, otherwise the conception remains, as we say,
without sense, that is, without meaning. Mathematics fulfils this
requirement by the construction of the figure, which is a phenomenon
evident to the senses. The same science finds support and significance
in number; this in its turn finds it in the fingers, or in counters,
or in lines and points. The conception itself is always produced a
priori, together with the synthetical principles or formulas from such
conceptions; but the proper employment of them, and their
application to objects, can exist nowhere but in experience, the
possibility of which, as regards its form, they contain a priori.

That this is also the case with all of the categories and the
principles based upon them is evident from the fact that we cannot
render intelligible the possibility of an object corresponding to them
without having recourse to the conditions of sensibility,
consequently, to the form of phenomena, to which, as their only proper
objects, their use must therefore be confined, inasmuch as, if this
condition is removed, all significance, that is, all relation to an
object, disappears, and no example can be found to make it
comprehensible what sort of things we ought to think under such

The conception of quantity cannot be explained except by saying that
it is the determination of a thing whereby it can be cogitated how
many times one is placed in it. But this "how many times" is based
upon successive repetition, consequently upon time and the synthesis
of the homogeneous therein. Reality, in contradistinction to negation,
can be explained only by cogitating a time which is either filled
therewith or is void. If I leave out the notion of permanence (which
is existence in all time), there remains in the conception of
substance nothing but the logical notion of subject, a notion of which
I endeavour to realize by representing to myself something that can
exist only as a subject. But not only am I perfectly ignorant of any
conditions under which this logical prerogative can belong to a thing,
I can make nothing out of the notion, and draw no inference from it,
because no object to which to apply the conception is determined,
and we consequently do not know whether it has any meaning at all.
In like manner, if I leave out the notion of time, in which
something follows upon some other thing in conformity with a rule,
I can find nothing in the pure category, except that there is a
something of such a sort that from it a conclusion may be drawn as
to the existence of some other thing. But in this case it would not
only be impossible to distinguish between a cause and an effect,
but, as this power to draw conclusions requires conditions of which
I am quite ignorant, the conception is not determined as to the mode
in which it ought to apply to an object. The so-called principle:
"Everything that is contingent has a cause," comes with a gravity
and self-assumed authority that seems to require no support from
without. But, I ask, what is meant by contingent? The answer is that
the non-existence of which is possible. But I should like very well
to know by what means this possibility of non-existence is to be
cognized, if we do not represent to ourselves a succession in the
series of phenomena, and in this succession an existence which follows
a non-existence, or conversely, consequently, change. For to say, that
the non-existence of a thing is not self-contradictory is a lame
appeal to a logical condition, which is no doubt a necessary condition
of the existence of the conception, but is far from being sufficient
for the real objective possibility of non-existence. I can
annihilate in thought every existing substance without
self-contradiction, but I cannot infer from this their objective
contingency in existence, that is to say, the possibility of their
non-existence in itself. As regards the category of community, it
may easily be inferred that, as the pure categories of substance and
causality are incapable of a definition and explanation sufficient
to determine their object without the aid of intuition, the category
of reciprocal causality in the relation of substances to each other
(commercium) is just as little susceptible thereof. Possibility,
existence, and necessity nobody has ever yet been able to explain
without being guilty of manifest tautology, when the definition has
been drawn entirely from the pure understanding. For the
substitution of the logical possibility of the conception--the
condition of which is that it be not self-contradictory, for the
transcendental possibility of things--the condition of which is that
there be an object corresponding to the conception, is a trick which
can only deceive the inexperienced.*

[*Footnote: In one word, to none of these conceptions belongs a
corresponding object, and consequently their real possibility cannot
be demonstrated, if we take away sensuous intuition--the only intuition
which we possess--and there then remains nothing but the logical
possibility, that is, the fact that the conception or thought is
possible--which, however, is not the question; what we want to know
being, whether it relates to an object and thus possesses any meaning.]

It follows incontestably, that the pure conceptions of the
understanding are incapable of transcendental, and must always be of
empirical use alone, and that the principles of the pure understanding
relate only to the general conditions of a possible experience, to
objects of the senses, and never to things in general, apart from
the mode in which we intuite them.

Transcendental analytic has accordingly this important result, to
wit, that the understanding is competent' effect nothing a priori,
except the anticipation of the form of a possible experience in
general, and that, as that which is not phenomenon cannot be an object
of experience, it can never overstep the limits of sensibility, within
which alone objects are presented to us. Its principles are merely
principles of the exposition of phenomena, and the proud name of an
ontology, which professes to present synthetical cognitions a priori
of things in general in a systematic doctrine, must give place to
the modest title of analytic of the pure understanding.

Thought is the act of referring a given intuition to an object. If
the mode of this intuition is unknown to us, the object is merely
transcendental, and the conception of the understanding is employed
only transcendentally, that is, to produce unity in the thought of
a manifold in general. Now a pure category, in which all conditions
of sensuous intuition--as the only intuition we possess--are
abstracted, does not determine an object, but merely expresses the
thought of an object in general, according to different modes. Now,
to employ a conception, the function of judgement is required, by which
an object is subsumed under the conception, consequently the at
least formal condition, under which something can be given in
intuition. Failing this condition of judgement (schema), subsumption
is impossible; for there is in such a case nothing given, which may
be subsumed under the conception. The merely transcendental use of
the categories is therefore, in fact, no use at all and has no determined,
or even, as regards its form, determinable object. Hence it follows
that the pure category is incompetent to establish a synthetical a
priori principle, and that the principles of the pure understanding
are only of empirical and never of transcendental use, and that beyond
the sphere of possible experience no synthetical a priori principles
are possible.

It may be advisable, therefore, to express ourselves thus. The
pure categories, apart from the formal conditions of sensibility, have
a merely transcendental meaning, but are nevertheless not of
transcendental use, because this is in itself impossible, inasmuch
as all the conditions of any employment or use of them (in judgements)
are absent, to wit, the formal conditions of the subsumption of an
object under these conceptions. As, therefore, in the character of
pure categories, they must be employed empirically, and cannot be
employed transcendentally, they are of no use at all, when separated
from sensibility, that is, they cannot be applied to an object. They
are merely the pure form of the employment of the understanding in
respect of objects in general and of thought, without its being at
the same time possible to think or to determine any object by their
means. But there lurks at the foundation of this subject an illusion
which it is very difficult to avoid. The categories are not based,
as regards their origin, upon sensibility, like the forms of
intuition, space, and time; they seem, therefore, to be capable of
an application beyond the sphere of sensuous objects. But this is
not the case. They are nothing but mere forms of thought, which
contain only the logical faculty of uniting a priori in
consciousness the manifold given in intuition. Apart, then, from the
only intuition possible for us, they have still less meaning than
the pure sensuous forms, space and time, for through them an object
is at least given, while a mode of connection of the manifold, when
the intuition which alone gives the manifold is wanting, has no meaning
at all. At the same time, when we designate certain objects as
phenomena or sensuous existences, thus distinguishing our mode of
intuiting them from their own nature as things in themselves, it is
evident that by this very distinction we as it were place the
latter, considered in this their own nature, although we do not so
intuite them, in opposition to the former, or, on the other hand, we
do so place other possible things, which are not objects of our
senses, but are cogitated by the understanding alone, and call them
intelligible existences (noumena). Now the question arises whether
the pure conceptions of our understanding do possess significance in
respect of these latter, and may possibly be a mode of cognizing them.

But we are met at the very commencement with an ambiguity, which may
easily occasion great misapprehension. The understanding, when it
terms an object in a certain relation phenomenon, at the same time
forms out of this relation a representation or notion of an object
in itself, and hence believes that it can form also conceptions of
such objects. Now as the understanding possesses no other
fundamental conceptions besides the categories, it takes for granted
that an object considered as a thing in itself must be capable of
being thought by means of these pure conceptions, and is thereby led
to hold the perfectly undetermined conception of an intelligible
existence, a something out of the sphere of our sensibility, for a
determinate conception of an existence which we can cognize in some
way or other by means of the understanding.

If, by the term noumenon, we understand a thing so far as it is
not an object of our sensuous intuition, thus making abstraction of
our mode of intuiting it, this is a noumenon in the negative sense
of the word. But if we understand by it an object of a non-sensuous
intuition, we in this case assume a peculiar mode of intuition, an
intellectual intuition, to wit, which does not, however, belong to
us, of the very possibility of which we have no notion--and this is
a noumenon in the positive sense.

The doctrine of sensibility is also the doctrine of noumena in the
negative sense, that is, of things which the understanding is
obliged to cogitate apart from any relation to our mode of
intuition, consequently not as mere phenomena, but as things in
themselves. But the understanding at the same time comprehends that
it cannot employ its categories for the consideration of things in
themselves, because these possess significance only in relation to
the unity of intuitions in space and time, and that they are competent
to determine this unity by means of general a priori connecting
conceptions only on account of the pure ideality of space and time.
Where this unity of time is not to be met with, as is the case with
noumena, the whole use, indeed the whole meaning of the categories
is entirely lost, for even the possibility of things to correspond
to the categories is in this case incomprehensible. On this point,
I need only refer the reader to what I have said at the commencement
of the General Remark appended to the foregoing chapter. Now, the
possibility of a thing can never be proved from the fact that the
conception of it is not self-contradictory, but only by means of an
intuition corresponding to the conception. If, therefore, we wish to
apply the categories to objects which cannot be regarded as phenomena,
we must have an intuition different from the sensuous, and in this
case the objects would be a noumena in the positive sense of the word.
Now, as such an intuition, that is, an intellectual intuition, is no
part of our faculty of cognition, it is absolutely impossible for
the categories to possess any application beyond the limits of
experience. It may be true that there are intelligible existences to
which our faculty of sensuous intuition has no relation, and cannot
be applied, but our conceptions of the understanding, as mere forms
of thought for our sensuous intuition, do not extend to these. What,
therefore, we call noumenon must be understood by us as such in a
negative sense.

If I take away from an empirical intuition all thought (by means of
the categories), there remains no cognition of any object; for by
means of mere intuition nothing is cogitated, and, from the
existence of such or such an affection of sensibility in me, it does
not follow that this affection or representation has any relation to
an object without me. But if I take away all intuition, there still
remains the form of thought, that is, the mode of determining an
object for the manifold of a possible intuition. Thus the categories
do in some measure really extend further than sensuous intuition,
inasmuch as they think objects in general, without regard to the
mode (of sensibility) in which these objects are given. But they do
not for this reason apply to and determine a wider sphere of
objects, because we cannot assume that such can be given, without
presupposing the possibility of another than the sensuous mode of
intuition, a supposition we are not justified in making.

I call a conception problematical which contains in itself no
contradiction, and which is connected with other cognitions as a
limitation of given conceptions, but whose objective reality cannot
be cognized in any manner. The conception of a noumenon, that is, of
a thing which must be cogitated not as an object of sense, but as a
thing in itself (solely through the pure understanding), is not
self-contradictory, for we are not entitled to maintain that
sensibility is the only possible mode of intuition. Nay, further, this
conception is necessary to restrain sensuous intuition within the
bounds of phenomena, and thus to limit the objective validity of
sensuous cognition; for things in themselves, which lie beyond its
province, are called noumena for the very purpose of indicating that
this cognition does not extend its application to all that the
understanding thinks. But, after all, the possibility of such
noumena is quite incomprehensible, and beyond the sphere of phenomena,
all is for us a mere void; that is to say, we possess an understanding
whose province does problematically extend beyond this sphere, but
we do not possess an intuition, indeed, not even the conception of
a possible intuition, by means of which objects beyond the region of
sensibility could be given us, and in reference to which the
understanding might be employed assertorically. The conception of a
noumenon is therefore merely a limitative conception and therefore
only of negative use. But it is not an arbitrary or fictitious notion,
but is connected with the limitation of sensibility, without, however,
being capable of presenting us with any positive datum beyond this

The division of objects into phenomena and noumena, and of the world
into a mundus sensibilis and intelligibilis is therefore quite
inadmissible in a positive sense, although conceptions do certainly
admit of such a division; for the class of noumena have no determinate
object corresponding to them, and cannot therefore possess objective
validity. If we abandon the senses, how can it be made conceivable
that the categories (which are the only conceptions that could serve
as conceptions for noumena) have any sense or meaning at all, inasmuch
as something more than the mere unity of thought, namely, a possible
intuition, is requisite for their application to an object? The
conception of a noumenon, considered as merely problematical, is,
however, not only admissible, but, as a limitative conception of
sensibility, absolutely necessary. But, in this case, a noumenon is
not a particular intelligible object for our understanding; on the
contrary, the kind of understanding to which it could belong is itself
a problem, for we cannot form the most distant conception of the
possibility of an understanding which should cognize an object, not
discursively by means of categories, but intuitively in a non-sensuous
intuition. Our understanding attains in this way a sort of negative
extension. That is to say, it is not limited by, but rather limits,
sensibility, by giving the name of noumena to things, not considered
as phenomena, but as things in themselves. But it at the same time
prescribes limits to itself, for it confesses itself unable to cognize
these by means of the categories, and hence is compelled to cogitate
them merely as an unknown something.

I find, however, in the writings of modern authors, an entirely
different use of the expressions, mundus sensibilis and
intelligibilis, which quite departs from the meaning of the
ancients--an acceptation in which, indeed, there is to be found no
difficulty, but which at the same time depends on mere verbal
quibbling. According to this meaning, some have chosen to call the
complex of phenomena, in so far as it is intuited, mundus
sensibilis, but in so far as the connection thereof is cogitated
according to general laws of thought, mundus intelligibilis.
Astronomy, in so far as we mean by the word the mere observation of
the starry heaven, may represent the former; a system of astronomy,
such as the Copernican or Newtonian, the latter. But such twisting
of words is a mere sophistical subterfuge, to avoid a difficult
question, by modifying its meaning to suit our own convenience. To
be sure, understanding and reason are employed in the cognition of
phenomena; but the question is, whether these can be applied when
the object is not a phenomenon and in this sense we regard it if it
is cogitated as given to the understanding alone, and not to the
senses. The question therefore is whether, over and above the
empirical use of the understanding, a transcendental use is
possible, which applies to the noumenon as an object. This question
we have answered in the negative.

When therefore we say, the senses represent objects as they
appear, the understanding as they are, the latter statement must not
be understood in a transcendental, but only in an empirical
signification, that is, as they must be represented in the complete
connection of phenomena, and not according to what they may be,
apart from their relation to possible experience, consequently not
as objects of the pure understanding. For this must ever remain
unknown to us. Nay, it is also quite unknown to us whether any such
transcendental or extraordinary cognition is possible under any
circumstances, at least, whether it is possible by means of our
categories. Understanding and sensibility, with us, can determine
objects only in conjunction. If we separate them, we have intuitions
without conceptions, or conceptions without intuitions; in both cases,
representations, which we cannot apply to any determinate object.

If, after all our inquiries and explanations, any one still
hesitates to abandon the mere transcendental use of the categories,
let him attempt to construct with them a synthetical proposition. It
would, of course, be unnecessary for this purpose to construct an
analytical proposition, for that does not extend the sphere of the
understanding, but, being concerned only about what is cogitated in
the conception itself, it leaves it quite undecided whether the
conception has any relation to objects, or merely indicates the
unity of thought--complete abstraction being made of the modi in which
an object may be given: in such a proposition, it is sufficient for
the understanding to know what lies in the conception--to what it
applies is to it indifferent. The attempt must therefore be made
with a synthetical and so-called transcendental principle, for
example: "Everything that exists, exists as substance," or,
"Everything that is contingent exists as an effect of some other
thing, viz., of its cause." Now I ask, whence can the understanding
draw these synthetical propositions, when the conceptions contained
therein do not relate to possible experience but to things in
themselves (noumena)? Where is to be found the third term, which is
always requisite PURE site in a synthetical proposition, which may
connect in the same proposition conceptions which have no logical
(analytical) connection with each other? The proposition never will
be demonstrated, nay, more, the possibility of any such pure assertion
never can be shown, without making reference to the empirical use of
the understanding, and thus, ipso facto, completely renouncing pure
and non-sensuous judgement. Thus the conception of pure and merely
intelligible objects is completely void of all principles of its
application, because we cannot imagine any mode in which they might
be given, and the problematical thought which leaves a place open for
them serves only, like a void space, to limit the use of empirical
principles, without containing at the same time any other object of
cognition beyond their sphere.


Of the Equivocal Nature or Amphiboly of the Conceptions of
Reflection from the Confusion of the Transcendental with
the Empirical use of the Understanding.

Reflection (reflexio) is not occupied about objects themselves,
for the purpose of directly obtaining conceptions of them, but is that
state of the mind in which we set ourselves to discover the subjective
conditions under which we obtain conceptions. It is the
consciousness of the relation of given representations to the
different sources or faculties of cognition, by which alone their
relation to each other can be rightly determined. The first question
which occurs in considering our representations is to what faculty
of cognition do they belong? To the understanding or to the senses?
Many judgements are admitted to be true from mere habit or
inclination; but, because reflection neither precedes nor follows,
it is held to be a judgement that has its origin in the understanding.
All judgements do not require examination, that is, investigation into
the grounds of their truth. For, when they are immediately certain
(for example: "Between two points there can be only one straight
line"), no better or less mediate test of their truth can be found
than that which they themselves contain and express. But all
judgement, nay, all comparisons require reflection, that is, a
distinction of the faculty of cognition to which the given conceptions
belong. The act whereby I compare my representations with the
faculty of cognition which originates them, and whereby I
distinguish whether they are compared with each other as belonging
to the pure understanding or to sensuous intuition, I term
transcendental reflection. Now, the relations in which conceptions
can stand to each other are those of identity and difference, agreement
and opposition, of the internal and external, finally, of the
determinable and the determining (matter and form). The proper
determination of these relations rests on the question, to what
faculty of cognition they subjectively belong, whether to
sensibility or understanding? For, on the manner in which we solve
this question depends the manner in which we must cogitate these

Before constructing any objective judgement, we compare the
conceptions that are to be placed in the judgement, and observe
whether there exists identity (of many representations in one
conception), if a general judgement is to be constructed, or
difference, if a particular; whether there is agreement when
affirmative; and opposition when negative judgements are to be
constructed, and so on. For this reason we ought to call these
conceptions, conceptions of comparison (conceptus comparationis).
But as, when the question is not as to the logical form, but as to
the content of conceptions, that is to say, whether the things
themselves are identical or different, in agreement or opposition,
and so on, the things can have a twofold relation to our faculty of
cognition, to wit, a relation either to sensibility or to the
understanding, and as on this relation depends their relation to
each other, transcendental reflection, that is, the relation of
given representations to one or the other faculty of cognition, can
alone determine this latter relation. Thus we shall not be able to
discover whether the things are identical or different, in agreement
or opposition, etc., from the mere conception of the things by means
of comparison (comparatio), but only by distinguishing the mode of
cognition to which they belong, in other words, by means of
transcendental reflection. We may, therefore, with justice say, that
logical reflection is mere comparison, for in it no account is taken
of the faculty of cognition to which the given conceptions belong,
and they are consequently, as far as regards their origin, to be treated
as homogeneous; while transcendental reflection (which applies to
the objects themselves) contains the ground of the possibility of
objective comparison of representations with each other, and is
therefore very different from the former, because the faculties of
cognition to which they belong are not even the same. Transcendental
reflection is a duty which no one can neglect who wishes to
establish an a priori judgement upon things. We shall now proceed to
fulfil this duty, and thereby throw not a little light on the question
as to the determination of the proper business of the understanding.

1. Identity and Difference. When an object is presented to us
several times, but always with the same internal determinations
(qualitas et quantitas), it, if an object of pure understanding, is
always the same, not several things, but only one thing (numerica
identitas); but if a phenomenon, we do not concern ourselves with
comparing the conception of the thing with the conception of some
other, but, although they may be in this respect perfectly the same,
the difference of place at the same time is a sufficient ground for
asserting the numerical difference of these objects (of sense).
Thus, in the case of two drops of water, we may make complete
abstraction of all internal difference (quality and quantity), and,
the fact that they are intuited at the same time in different
places, is sufficient to justify us in holding them to be
numerically different. Leibnitz regarded phenomena as things in
themselves, consequently as intelligibilia, that is, objects of pure
understanding (although, on account of the confused nature of their
representations, he gave them the name of phenomena), and in this case
his principle of the indiscernible (principium identatis
indiscernibilium) is not to be impugned. But, as phenomena are objects
of sensibility, and, as the understanding, in respect of them, must
be employed empirically and not purely or transcendentally, plurality
and numerical difference are given by space itself as the condition
of external phenomena. For one part of space, although it may be
perfectly similar and equal to another part, is still without it,
and for this reason alone is different from the latter, which is added
to it in order to make up a greater space. It follows that this must
hold good of all things that are in the different parts of space at
the same time, however similar and equal one may be to another.

2. Agreement and Opposition. When reality is represented by the pure
understanding (realitas noumenon), opposition between realities is
incogitable--such a relation, that is, that when these realities are
connected in one subject, they annihilate the effects of each other
and may be represented in the formula 3 - 3 = 0. On the other hand,
the real in a phenomenon (realitas phaenomenon) may very well be in
mutual opposition, and, when united in the same subject, the one may
completely or in part annihilate the effect or consequence of the
other; as in the case of two moving forces in the same straight line
drawing or impelling a point in opposite directions, or in the case
of a pleasure counterbalancing a certain amount of pain.

3. The Internal and External. In an object of the pure
understanding, only that is internal which has no relation (as regards
its existence) to anything different from itself. On the other hand,
the internal determinations of a substantia phaenomenon in space are
nothing but relations, and it is itself nothing more than a complex
of mere relations. Substance in space we are cognizant of only through
forces operative in it, either drawing others towards itself
(attraction), or preventing others from forcing into itself (repulsion
and impenetrability). We know no other properties that make up the
conception of substance phenomenal in space, and which we term matter.
On the other hand, as an object of the pure understanding, every
substance must have internal determination and forces. But what
other internal attributes of such an object can I think than those
which my internal sense presents to me? That, to wit, which in
either itself thought, or something analogous to it. Hence Leibnitz,
who looked upon things as noumena, after denying them everything
like external relation, and therefore also composition or combination,
declared that all substances, even the component parts of matter, were
simple substances with powers of representation, in one word, monads.

4. Matter and Form. These two conceptions lie at the foundation of
all other reflection, so inseparably are they connected with every
mode of exercising the understanding. The former denotes the
determinable in general, the second its determination, both in a
transcendental sense, abstraction being made of every difference in
that which is given, and of the mode in which it is determined.
Logicians formerly termed the universal, matter, the specific
difference of this or that part of the universal, form. In a judgement
one may call the given conceptions logical matter (for the judgement),
the relation of these to each other (by means of the copula), the form
of the judgement. In an object, the composite parts thereof
(essentialia) are the matter; the mode in which they are connected
in the object, the form. In respect to things in general, unlimited
reality was regarded as the matter of all possibility, the
limitation thereof (negation) as the form, by which one thing is
distinguished from another according to transcendental conceptions.
The understanding demands that something be given (at least in the
conception), in order to be able to determine it in a certain
manner. Hence, in a conception of the pure understanding, the matter
precedes the form, and for this reason Leibnitz first assumed the
existence of things (monads) and of an internal power of
representation in them, in order to found upon this their external
relation and the community their state (that is, of their
representations). Hence, with him, space and time were possible--the
former through the relation of substances, the latter through the
connection of their determinations with each other, as causes and
effects. And so would it really be, if the pure understanding were
capable of an immediate application to objects, and if space and
time were determinations of things in themselves. But being merely
sensuous intuitions, in which we determine all objects solely as
phenomena, the form of intuition (as a subjective property of
sensibility) must antecede all matter (sensations), consequently space
and time must antecede all phenomena and all data of experience, and
rather make experience itself possible. But the intellectual
philosopher could not endure that the form should precede the things
themselves and determine their possibility; an objection perfectly
correct, if we assume that we intuite things as they are, although
with confused representation. But as sensuous intuition is a
peculiar subjective condition, which is a priori at the foundation
of all perception, and the form of which is primitive, the form must
be given per se, and so far from matter (or the things themselves
which appear) lying at the foundation of experience (as we must
conclude, if we judge by mere conceptions), the very possibility of
itself presupposes, on the contrary, a given formal intuition (space
and time).


Let me be allowed to term the position which we assign to a
conception either in the sensibility or in the pure understanding,
the transcendental place. In this manner, the appointment of the
position which must be taken by each conception according to the
difference in its use, and the directions for determining this place
to all conceptions according to rules, would be a transcendental
topic, a doctrine which would thoroughly shield us from the
surreptitious devices of the pure understanding and the delusions
which thence arise, as it would always distinguish to what faculty
of cognition each conception properly belonged. Every conception,
every title, under which many cognitions rank together, may be
called a logical place. Upon this is based the logical topic of
Aristotle, of which teachers and rhetoricians could avail
themselves, in order, under certain titles of thought, to observe what
would best suit the matter they had to treat, and thus enable
themselves to quibble and talk with fluency and an appearance of

Transcendental topic, on the contrary, contains nothing more than
the above-mentioned four titles of all comparison and distinction,
which differ from categories in this respect, that they do not
represent the object according to that which constitutes its
conception (quantity, reality), but set forth merely the comparison
of representations, which precedes our conceptions of things. But this
comparison requires a previous reflection, that is, a determination
of the place to which the representations of the things which are
compared belong, whether, to wit, they are cogitated by the pure
understanding, or given by sensibility.

Conceptions may be logically compared without the trouble of
inquiring to what faculty their objects belong, whether as noumena,
to the understanding, or as phenomena, to sensibility. If, however,
we wish to employ these conceptions in respect of objects, previous
transcendental reflection is necessary. Without this reflection I
should make a very unsafe use of these conceptions, and construct
pretended synthetical propositions which critical reason cannot
acknowledge and which are based solely upon a transcendental
amphiboly, that is, upon a substitution of an object of pure
understanding for a phenomenon.

For want of this doctrine of transcendental topic, and
consequently deceived by the amphiboly of the conceptions of
reflection, the celebrated Leibnitz constructed an intellectual system
of the world, or rather, believed himself competent to cognize the
internal nature of things, by comparing all objects merely with the
understanding and the abstract formal conceptions of thought. Our
table of the conceptions of reflection gives us the unexpected
advantage of being able to exhibit the distinctive peculiarities of
his system in all its parts, and at the same time of exposing the
fundamental principle of this peculiar mode of thought, which rested
upon naught but a misconception. He compared all things with each
other merely by means of conceptions, and naturally found no other
differences than those by which the understanding distinguishes its
pure conceptions one from another. The conditions of sensuous
intuition, which contain in themselves their own means of distinction,
he did not look upon as primitive, because sensibility was to him
but a confused mode of representation and not any particular source
of representations. A phenomenon was for him the representation of
the thing in itself, although distinguished from cognition by the
understanding only in respect of the logical form--the former with
its usual want of analysis containing, according to him, a certain
mixture of collateral representations in its conception of a thing,
which it is the duty of the understanding to separate and distinguish.
In one word, Leibnitz intellectualized phenomena, just as Locke, in
his system of noogony (if I may be allowed to make use of such
expressions), sensualized the conceptions of the understanding, that
is to say, declared them to be nothing more than empirical or abstract
conceptions of reflection. Instead of seeking in the understanding
and sensibility two different sources of representations, which,
however, can present us with objective judgements of things only in
conjunction, each of these great men recognized but one of these
faculties, which, in their opinion, applied immediately to things in
themselves, the other having no duty but that of confusing or
arranging the representations of the former.

Accordingly, the objects of sense were compared by Leibnitz as
things in general merely in the understanding.

1st. He compares them in regard to their identity or difference-
as judged by the understanding. As, therefore, he considered merely
the conceptions of objects, and not their position in intuition, in
which alone objects can be given, and left quite out of sight the
transcendental locale of these conceptions--whether, that is, their
object ought to be classed among phenomena, or among things in
themselves, it was to be expected that he should extend the
application of the principle of indiscernibles, which is valid
solely of conceptions of things in general, to objects of sense
(mundus phaenomenon), and that he should believe that he had thereby
contributed in no small degree to extend our knowledge of nature. In
truth, if I cognize in all its inner determinations a drop of water
as a thing in itself, I cannot look upon one drop as different from
another, if the conception of the one is completely identical with
that of the other. But if it is a phenomenon in space, it has a
place not merely in the understanding (among conceptions), but also
in sensuous external intuition (in space), and in this case, the physical
locale is a matter of indifference in regard to the internal
determinations of things, and one place, B, may contain a thing
which is perfectly similar and equal to another in a place, A, just
as well as if the two things were in every respect different from each
other. Difference of place without any other conditions, makes the
plurality and distinction of objects as phenomena, not only possible
in itself, but even necessary. Consequently, the above so-called law
is not a law of nature. It is merely an analytical rule for the
comparison of things by means of mere conceptions.

2nd. The principle: "Realities (as simple affirmations) never
logically contradict each other," is a proposition perfectly true
respecting the relation of conceptions, but, whether as regards
nature, or things in themselves (of which we have not the slightest
conception), is without any the least meaning. For real opposition,
in which A - B is = 0, exists everywhere, an opposition, that is, in
which one reality united with another in the same subject
annihilates the effects of the other--a fact which is constantly
brought before our eyes by the different antagonistic actions and
operations in nature, which, nevertheless, as depending on real
forces, must be called realitates phaenomena. General mechanics can
even present us with the empirical condition of this opposition in
an a priori rule, as it directs its attention to the opposition in
the direction of forces--a condition of which the transcendental
conception of reality can tell us nothing. Although M. Leibnitz did
not announce this proposition with precisely the pomp of a new
principle, he yet employed it for the establishment of new
propositions, and his followers introduced it into their
Leibnitzio-Wolfian system of philosophy. According to this
principle, for example, all evils are but consequences of the
limited nature of created beings, that is, negations, because these
are the only opposite of reality. (In the mere conception of a thing
in general this is really the case, but not in things as phenomena.)
In like manner, the upholders of this system deem it not only
possible, but natural also, to connect and unite all reality in one
being, because they acknowledge no other sort of opposition than
that of contradiction (by which the conception itself of a thing is
annihilated), and find themselves unable to conceive an opposition
of reciprocal destruction, so to speak, in which one real cause
destroys the effect of another, and the conditions of whose
representation we meet with only in sensibility.

3rd. The Leibnitzian monadology has really no better foundation than
on this philosopher's mode of falsely representing the difference of
the internal and external solely in relation to the understanding.
Substances, in general, must have something inward, which is therefore
free from external relations, consequently from that of composition
also. The simple--that which can be represented by a unit--is
therefore the foundation of that which is internal in things in
themselves. The internal state of substances cannot therefore
consist in place, shape, contact, or motion, determinations which
are all external relations, and we can ascribe to them no other than
that whereby we internally determine our faculty of sense itself, that
is to say, the state of representation. Thus, then, were constructed
the monads, which were to form the elements of the universe, the
active force of which consists in representation, the effects of
this force being thus entirely confined to themselves.

For the same reason, his view of the possible community of
substances could not represent it but as a predetermined harmony,
and by no means as a physical influence. For inasmuch as everything
is occupied only internally, that is, with its own representations,
the state of the representations of one substance could not stand in
active and living connection with that of another, but some third
cause operating on all without exception was necessary to make the
different states correspond with one another. And this did not
happen by means of assistance applied in each particular case (systema
assistentiae), but through the unity of the idea of a cause occupied
and connected with all substances, in which they necessarily
receive, according to the Leibnitzian school, their existence and
permanence, consequently also reciprocal correspondence, according
to universal laws.

4th. This philosopher's celebrated doctrine of space and time, in
which he intellectualized these forms of sensibility, originated in
the same delusion of transcendental reflection. If I attempt to
represent by the mere understanding, the external relations of things,
I can do so only by employing the conception of their reciprocal
action, and if I wish to connect one state of the same thing with
another state, I must avail myself of the notion of the order of cause
and effect. And thus Leibnitz regarded space as a certain order in
the community of substances, and time as the dynamical sequence of
their states. That which space and time possess proper to themselves
and independent of things, he ascribed to a necessary confusion in
our conceptions of them, whereby that which is a mere form of dynamical
relations is held to be a self-existent intuition, antecedent even
to things themselves. Thus space and time were the intelligible form
of the connection of things (substances and their states) in
themselves. But things were intelligible substances (substantiae
noumena). At the same time, he made these conceptions valid of
phenomena, because he did not allow to sensibility a peculiar mode
of intuition, but sought all, even the empirical representation of
objects, in the understanding, and left to sense naught but the
despicable task of confusing and disarranging the representations of
the former.

But even if we could frame any synthetical proposition concerning
things in themselves by means of the pure understanding (which is
impossible), it could not apply to phenomena, which do not represent
things in themselves. In such a case I should be obliged in
transcendental reflection to compare my conceptions only under the
conditions of sensibility, and so space and time would not be
determinations of things in themselves, but of phenomena. What
things may be in themselves, I know not and need not know, because
a thing is never presented to me otherwise than as a phenomenon.

I must adopt the same mode of procedure with the other conceptions
of reflection. Matter is substantia phaenomenon. That in it which is
internal I seek to discover in all parts of space which it occupies,
and in all the functions and operations it performs, and which are
indeed never anything but phenomena of the external sense. I cannot
therefore find anything that is absolutely, but only what is
comparatively internal, and which itself consists of external
relations. The absolutely internal in matter, and as it should be
according to the pure understanding, is a mere chimera, for matter
is not an object for the pure understanding. But the transcendental
object, which is the foundation of the phenomenon which we call
matter, is a mere nescio quid, the nature of which we could not
understand, even though someone were found able to tell us. For we
can understand nothing that does not bring with it something in
intuition corresponding to the expressions employed. If, by the
complaint of being unable to perceive the internal nature of things,
it is meant that we do not comprehend by the pure understanding what
the things which appear to us may be in themselves, it is a silly
and unreasonable complaint; for those who talk thus really desire that
we should be able to cognize, consequently to intuite, things
without senses, and therefore wish that we possessed a faculty of
cognition perfectly different from the human faculty, not merely in
degree, but even as regards intuition and the mode thereof, so that
thus we should not be men, but belong to a class of beings, the
possibility of whose existence, much less their nature and
constitution, we have no means of cognizing. By observation and
analysis of phenomena we penetrate into the interior of nature, and
no one can say what progress this knowledge may make in time. But those
transcendental questions which pass beyond the limits of nature, we
could never answer, even although all nature were laid open to us,
because we have not the power of observing our own mind with any other
intuition than that of our internal sense. For herein lies the mystery
of the origin and source of our faculty of sensibility. Its
application to an object, and the transcendental ground of this
unity of subjective and objective, lie too deeply concealed for us,
who cognize ourselves only through the internal sense, consequently
as phenomena, to be able to discover in our existence anything but
phenomena, the non-sensuous cause of which we at the same time
earnestly desire to penetrate to.

The great utility of this critique of conclusions arrived at by
the processes of mere reflection consists in its clear demonstration
of the nullity of all conclusions respecting objects which are
compared with each other in the understanding alone, while it at the
same time confirms what we particularly insisted on, namely, that,
although phenomena are not included as things in themselves among
the objects of the pure understanding, they are nevertheless the
only things by which our cognition can possess objective reality, that
is to say, which give us intuitions to correspond with our

When we reflect in a purely logical manner, we do nothing more
than compare conceptions in our understanding, to discover whether
both have the same content, whether they are self-contradictory or
not, whether anything is contained in either conception, which of
the two is given, and which is merely a mode of thinking that given.
But if I apply these conceptions to an object in general (in the
transcendental sense), without first determining whether it is an
object of sensuous or intellectual intuition, certain limitations
present themselves, which forbid us to pass beyond the conceptions
and render all empirical use of them impossible. And thus these
limitations prove that the representation of an object as a thing in
general is not only insufficient, but, without sensuous
determination and independently of empirical conditions,
self-contradictory; that we must therefore make abstraction of all
objects, as in logic, or, admitting them, must think them under
conditions of sensuous intuition; that, consequently, the intelligible
requires an altogether peculiar intuition, which we do not possess,
and in the absence of which it is for us nothing; while, on the
other hand phenomena cannot be objects in themselves. For, when I
merely think things in general, the difference in their external
relations cannot constitute a difference in the things themselves;
on the contrary, the former presupposes the latter, and if the
conception of one of two things is not internally different from
that of the other, I am merely thinking the same thing in different
relations. Further, by the addition of one affirmation (reality) to
the other, the positive therein is really augmented, and nothing is
abstracted or withdrawn from it; hence the real in things cannot be
in contradiction with or opposition to itself--and so on.

The true use of the conceptions of reflection in the employment of
the understanding has, as we have shown, been so misconceived by
Leibnitz, one of the most acute philosophers of either ancient or
modern times, that he has been misled into the construction of a
baseless system of intellectual cognition, which professes to
determine its objects without the intervention of the senses. For this
reason, the exposition of the cause of the amphiboly of these
conceptions, as the origin of these false principles, is of great
utility in determining with certainty the proper limits of the

It is right to say whatever is affirmed or denied of the whole of
a conception can be affirmed or denied of any part of it (dictum de
omni et nullo); but it would be absurd so to alter this logical
proposition as to say whatever is not contained in a general
conception is likewise not contained in the particular conceptions
which rank under it; for the latter are particular conceptions, for
the very reason that their content is greater than that which is
cogitated in the general conception. And yet the whole intellectual
system of Leibnitz is based upon this false principle, and with it
must necessarily fall to the ground, together with all the ambiguous
principles in reference to the employment of the understanding which
have thence originated.

Leibnitz's principle of the identity of indiscernibles or
indistinguishables is really based on the presupposition that, if in
the conception of a thing a certain distinction is not to be found,
it is also not to be met with in things themselves; that, consequently,
all things are completely identical (numero eadem) which are not
distinguishable from each other (as to quality or quantity) in our
conceptions of them. But, as in the mere conception of anything
abstraction has been made of many necessary conditions of intuition,
that of which abstraction has been made is rashly held to be
non-existent, and nothing is attributed to the thing but what is
contained in its conception.

The conception of a cubic foot of space, however I may think it,
is in itself completely identical. But two cubic feet in space are
nevertheless distinct from each other from the sole fact of their
being in different places (they are numero diversa); and these
places are conditions of intuition, wherein the object of this
conception is given, and which do not belong to the conception, but
to the faculty of sensibility. In like manner, there is in the conception
of a thing no contradiction when a negative is not connected with an
affirmative; and merely affirmative conceptions cannot, in
conjunction, produce any negation. But in sensuous intuition,
wherein reality (take for example, motion) is given, we find
conditions (opposite directions)--of which abstraction has been made
in the conception of motion in general--which render possible a
contradiction or opposition (not indeed of a logical kind)--and
which from pure positives produce zero = 0. We are therefore not
justified in saying that all reality is in perfect agreement and
harmony, because no contradiction is discoverable among its
conceptions.* According to mere conceptions, that which is internal
is the substratum of all relations or external determinations. When,
therefore, I abstract all conditions of intuition, and confine
myself solely to the conception of a thing in general, I can make
abstraction of all external relations, and there must nevertheless
remain a conception of that which indicates no relation, but merely
internal determinations. Now it seems to follow that in everything
(substance) there is something which is absolutely internal and
which antecedes all external determinations, inasmuch as it renders
them possible; and that therefore this substratum is something which
does not contain any external relations and is consequently simple
(for corporeal things are never anything but relations, at least of
their parts external to each other); and, inasmuch as we know of no
other absolutely internal determinations than those of the internal
sense, this substratum is not only simple, but also, analogously
with our internal sense, determined through representations, that is
to say, all things are properly monads, or simple beings endowed
with the power of representation. Now all this would be perfectly
correct, if the conception of a thing were the only necessary
condition of the presentation of objects of external intuition. It
is, on the contrary, manifest that a permanent phenomenon in space
(impenetrable extension) can contain mere relations, and nothing
that is absolutely internal, and yet be the primary substratum of
all external perception. By mere conceptions I cannot think anything
external, without, at the same time, thinking something internal,
for the reason that conceptions of relations presuppose given
things, and without these are impossible. But, as an intuition there
is something (that is, space, which, with all it contains, consists
of purely formal, or, indeed, real relations) which is not found in
the mere conception of a thing in general, and this presents to us
the substratum which could not be cognized through conceptions alone,
I cannot say: because a thing cannot be represented by mere
conceptions without something absolutely internal, there is also, in
the things themselves which are contained under these conceptions,
and in their intuition nothing external to which something absolutely
internal does not serve as the foundation. For, when we have made
abstraction of all the conditions of intuition, there certainly
remains in the mere conception nothing but the internal in general,
through which alone the external is possible. But this necessity,
which is grounded upon abstraction alone, does not obtain in the
case of things themselves, in so far as they are given in intuition
with such determinations as express mere relations, without having
anything internal as their foundation; for they are not things of a
thing of which we can neither for they are not things in themselves,
but only phenomena. What we cognize in matter is nothing but relations
(what we call its internal determinations are but comparatively
internal). But there are some self-subsistent and permanent, through
which a determined object is given. That I, when abstraction is made
of these relations, have nothing more to think, does not destroy the
conception of a thing as phenomenon, nor the conception of an object
in abstracto, but it does away with the possibility of an object
that is determinable according to mere conceptions, that is, of a
noumenon. It is certainly startling to hear that a thing consists
solely of relations; but this thing is simply a phenomenon, and cannot
be cogitated by means of the mere categories: it does itself consist
in the mere relation of something in general to the senses. In the
same way, we cannot cogitate relations of things in abstracto, if we
commence with conceptions alone, in any other manner than that one
is the cause of determinations in the other; for that is itself the
conception of the understanding or category of relation. But, as in
this case we make abstraction of all intuition, we lose altogether
the mode in which the manifold determines to each of its parts its
place, that is, the form of sensibility (space); and yet this mode
antecedes all empirical causality.

[*Footnote: If any one wishes here to have recourse to the usual
subterfuge, and to say, that at least realitates noumena cannot be
in opposition to each other, it will be requisite for him to adduce
an example of this pure and non-sensuous reality, that it may be understood
whether the notion represents something or nothing. But an example
cannot be found except in experience, which never presents to us
anything more than phenomena; and thus the proposition means nothing
more than that the conception which contains only affirmatives does
not contain anything negative--a proposition nobody ever doubted.]

If by intelligible objects we understand things which can be thought
by means of the pure categories, without the need of the schemata of
sensibility, such objects are impossible. For the condition of the
objective use of all our conceptions of understanding is the mode of
our sensuous intuition, whereby objects are given; and, if we make
abstraction of the latter, the former can have no relation to an
object. And even if we should suppose a different kind of intuition
from our own, still our functions of thought would have no use or
signification in respect thereof. But if we understand by the term,
objects of a non-sensuous intuition, in respect of which our
categories are not valid, and of which we can accordingly have no
knowledge (neither intuition nor conception), in this merely
negative sense noumena must be admitted. For this is no more than
saying that our mode of intuition is not applicable to all things,
but only to objects of our senses, that consequently its objective
validity is limited, and that room is therefore left for another
kind of intuition, and thus also for things that may be objects of
it. But in this sense the conception of a noumenon is problematical,
that is to say, it is the notion of that it that it is possible, nor
that it is impossible, inasmuch as we do not know of any mode of
intuition besides the sensuous, or of any other sort of conceptions
than the categories--a mode of intuition and a kind of conception
neither of which is applicable to a non-sensuous object. We are on
this account incompetent to extend the sphere of our objects of
thought beyond the conditions of our sensibility, and to assume the
existence of objects of pure thought, that is, of noumena, inasmuch
as these have no true positive signification. For it must be confessed
of the categories that they are not of themselves sufficient for the
cognition of things in themselves and, without the data of
sensibility, are mere subjective forms of the unity of the
understanding. Thought is certainly not a product of the senses, and
in so far is not limited by them, but it does not therefore follow
that it may be employed purely and without the intervention of
sensibility, for it would then be without reference to an object.
And we cannot call a noumenon an object of pure thought; for the
representation thereof is but the problematical conception of an
object for a perfectly different intuition and a perfectly different
understanding from ours, both of which are consequently themselves
problematical. The conception of a noumenon is therefore not the
conception of an object, but merely a problematical conception
inseparably connected with the limitation of our sensibility. That
is to say, this conception contains the answer to the question: "Are
there objects quite unconnected with, and independent of, our
intuition?"--a question to which only an indeterminate answer can be
given. That answer is: "Inasmuch as sensuous intuition does not
apply to all things without distinction, there remains room for
other and different objects." The existence of these problematical
objects is therefore not absolutely denied, in the absence of a
determinate conception of them, but, as no category is valid in
respect of them, neither must they be admitted as objects for our

Understanding accordingly limits sensibility, without at the same
time enlarging its own field. While, moreover, it forbids
sensibility to apply its forms and modes to things in themselves and
restricts it to the sphere of phenomena, it cogitates an object in
itself, only, however, as a transcendental object, which is the
cause of a phenomenon (consequently not itself a phenomenon), and
which cannot be thought either as a quantity or as reality, or as
substance (because these conceptions always require sensuous forms
in which to determine an object)--an object, therefore, of which we
are quite unable to say whether it can be met with in ourselves or
out of us, whether it would be annihilated together with sensibility,
or, if this were taken away, would continue to exist. If we wish to
call this object a noumenon, because the representation of it is
non-sensuous, we are at liberty to do so. But as we can apply to it
none of the conceptions of our understanding, the representation is
for us quite void, and is available only for the indication of the
limits of our sensuous intuition, thereby leaving at the same time
an empty space, which we are competent to fill by the aid neither of
possible experience, nor of the pure understanding.

The critique of the pure understanding, accordingly, does not permit
us to create for ourselves a new field of objects beyond those which
are presented to us as phenomena, and to stray into intelligible
worlds; nay, it does not even allow us to endeavour to form so much
as a conception of them. The specious error which leads to this--and
which is a perfectly excusable one--lies in the fact that the
employment of the understanding, contrary to its proper purpose and
destination, is made transcendental, and objects, that is, possible
intuitions, are made to regulate themselves according to
conceptions, instead of the conceptions arranging themselves according
to the intuitions, on which alone their own objective validity
rests. Now the reason of this again is that apperception, and with
it thought, antecedes all possible determinate arrangement of
representations. Accordingly we think something in general and
determine it on the one hand sensuously, but, on the other,
distinguish the general and in abstracto represented object from
this particular mode of intuiting it. In this case there remains a
mode of determining the object by mere thought, which is really but
a logical form without content, which, however, seems to us to be a
mode of the existence of the object in itself (noumenon), without
regard to intuition which is limited to our senses.

Before ending this transcendental analytic, we must make an
addition, which, although in itself of no particular importance, seems
to be necessary to the completeness of the system. The highest
conception, with which a transcendental philosophy commonly begins,
is the division into possible and impossible. But as all division
presupposes a divided conception, a still higher one must exist, and
this is the conception of an object in general--problematically
understood and without its being decided whether it is something or
nothing. As the categories are the only conceptions which apply to
objects in general, the distinguishing of an object, whether it is
something or nothing, must proceed according to the order and
direction of the categories.

1. To the categories of quantity, that is, the conceptions of all,
many, and one, the conception which annihilates all, that is, the
conception of none, is opposed. And thus the object of a conception,
to which no intuition can be found to correspond, is = nothing. That
is, it is a conception without an object (ens rationis), like noumena,
which cannot be considered possible in the sphere of reality, though
they must not therefore be held to be impossible--or like certain
new fundamental forces in matter, the existence of which is
cogitable without contradiction, though, as examples from experience
are not forthcoming, they must not be regarded as possible.

2. Reality is something; negation is nothing, that is, a
conception of the absence of an object, as cold, a shadow (nihil

3. The mere form of intuition, without substance, is in itself no
object, but the merely formal condition of an object (as
phenomenon), as pure space and pure time. These are certainly
something, as forms of intuition, but are not themselves objects which
are intuited (ens imaginarium).

4. The object of a conception which is self-contradictory, is
nothing, because the conception is nothing--is impossible, as a figure
composed of two straight lines (nihil negativum).

The table of this division of the conception of nothing (the
corresponding division of the conception of something does not require
special description) must therefore be arranged as follows:


As Empty Conception
without object,
ens rationis
2 3
Empty object of Empty intuition
a conception, without object,
nihil privativum ens imaginarium
Empty object
without conception,
nihil negativum

We see that the ens rationis is distinguished from the nihil
negativum or pure nothing by the consideration that the former must
not be reckoned among possibilities, because it is a mere fiction-
though not self-contradictory, while the latter is completely
opposed to all possibility, inasmuch as the conception annihilates
itself. Both, however, are empty conceptions. On the other hand,
the nihil privativum and ens imaginarium are empty data for
conceptions. If light be not given to the senses, we cannot
represent to ourselves darkness, and if extended objects are not
perceived, we cannot represent space. Neither the negation, nor the
mere form of intuition can, without something real, be an object.



I. Of Transcendental Illusory Appearance.

We termed dialectic in general a logic of appearance. This does
not signify a doctrine of probability; for probability is truth,
only cognized upon insufficient grounds, and though the information
it gives us is imperfect, it is not therefore deceitful. Hence it must
not be separated from the analytical part of logic. Still less must
phenomenon and appearance be held to be identical. For truth or
illusory appearance does not reside in the object, in so far as it
is intuited, but in the judgement upon the object, in so far as it
is thought. It is, therefore, quite correct to say that the senses
do not err, not because they always judge correctly, but because
they do not judge at all. Hence truth and error, consequently also,
illusory appearance as the cause of error, are only to be found in
a judgement, that is, in the relation of an object to our understanding.
In a cognition which completely harmonizes with the laws of the
understanding, no error can exist. In a representation of the
senses--as not containing any judgement--there is also no error. But
no power of nature can of itself deviate from its own laws. Hence
neither the understanding per se (without the influence of another
cause), nor the senses per se, would fall into error; the former could
not, because, if it acts only according to its own laws, the effect
(the judgement) must necessarily accord with these laws. But in
accordance with the laws of the understanding consists the formal
element in all truth. In the senses there is no judgement--neither
a true nor a false one. But, as we have no source of cognition besides
these two, it follows that error is caused solely by the unobserved
influence of the sensibility upon the understanding. And thus it
happens that the subjective grounds of a judgement and are
confounded with the objective, and cause them to deviate from their
proper determination,* just as a body in motion would always of itself
proceed in a straight line, but if another impetus gives to it a
different direction, it will then start off into a curvilinear line
of motion. To distinguish the peculiar action of the understanding
from the power which mingles with it, it is necessary to consider an
erroneous judgement as the diagonal between two forces, that determine
the judgement in two different directions, which, as it were, form
an angle, and to resolve this composite operation into the simple ones
of the understanding and the sensibility. In pure a priori
judgements this must be done by means of transcendental reflection,
whereby, as has been already shown, each representation has its
place appointed in the corresponding faculty of cognition, and
consequently the influence of the one faculty upon the other is made

[*Footnote: Sensibility, subjected to the understanding, as the object
upon which the understanding employs its functions, is the source of
real cognitions. But, in so far as it exercises an influence upon the
action of the understanding and determines it to judgement,
sensibility is itself the cause of error.]

It is not at present our business to treat of empirical illusory
appearance (for example, optical illusion), which occurs in the
empirical application of otherwise correct rules of the understanding,
and in which the judgement is misled by the influence of
imagination. Our purpose is to speak of transcendental illusory
appearance, which influences principles--that are not even applied
to experience, for in this case we should possess a sure test of their
correctness--but which leads us, in disregard of all the warnings of
criticism, completely beyond the empirical employment of the
categories and deludes us with the chimera of an extension of the
sphere of the pure understanding. We shall term those principles the
application of which is confined entirely within the limits of
possible experience, immanent; those, on the other hand, which
transgress these limits, we shall call transcendent principles. But
by these latter I do not understand principles of the transcendental
use or misuse of the categories, which is in reality a mere fault of
the judgement when not under due restraint from criticism, and
therefore not paying sufficient attention to the limits of the
sphere in which the pure understanding is allowed to exercise its
functions; but real principles which exhort us to break down all those
barriers, and to lay claim to a perfectly new field of cognition,
which recognizes no line of demarcation. Thus transcendental and
transcendent are not identical terms. The principles of the pure
understanding, which we have already propounded, ought to be of
empirical and not of transcendental use, that is, they are not
applicable to any object beyond the sphere of experience. A
principle which removes these limits, nay, which authorizes us to
overstep them, is called transcendent. If our criticism can succeed
in exposing the illusion in these pretended principles, those which
are limited in their employment to the sphere of experience may be
called, in opposition to the others, immanent principles of the pure

Logical illusion, which consists merely in the imitation of the form
of reason (the illusion in sophistical syllogisms), arises entirely
from a want of due attention to logical rules. So soon as the
attention is awakened to the case before us, this illusion totally
disappears. Transcendental illusion, on the contrary, does not cease
to exist, even after it has been exposed, and its nothingness
clearly perceived by means of transcendental criticism. Take, for
example, the illusion in the proposition: "The world must have a
beginning in time." The cause of this is as follows. In our reason,
subjectively considered as a faculty of human cognition, there exist
fundamental rules and maxims of its exercise, which have completely
the appearance of objective principles. Now from this cause it happens
that the subjective necessity of a certain connection of our
conceptions, is regarded as an objective necessity of the
determination of things in themselves. This illusion it is
impossible to avoid, just as we cannot avoid perceiving that the sea
appears to be higher at a distance than it is near the shore,
because we see the former by means of higher rays than the latter,
or, which is a still stronger case, as even the astronomer cannot
prevent himself from seeing the moon larger at its rising than some
time afterwards, although he is not deceived by this illusion.

Transcendental dialectic will therefore content itself with exposing
the illusory appearance in transcendental judgements, and guarding
us against it; but to make it, as in the case of logical illusion,
entirely disappear and cease to be illusion is utterly beyond its
power. For we have here to do with a natural and unavoidable illusion,
which rests upon subjective principles and imposes these upon us as
objective, while logical dialectic, in the detection of sophisms,
has to do merely with an error in the logical consequence of the
propositions, or with an artificially constructed illusion, in
imitation of the natural error. There is, therefore, a natural and
unavoidable dialectic of pure reason--not that in which the bungler,
from want of the requisite knowledge, involves himself, nor that which
the sophist devises for the purpose of misleading, but that which is
an inseparable adjunct of human reason, and which, even after its
illusions have been exposed, does not cease to deceive, and
continually to lead reason into momentary errors, which it becomes
necessary continually to remove.

II. Of Pure Reason as the Seat of Transcendental Illusory Appearance.


All our knowledge begins with sense, proceeds thence to
understanding, and ends with reason, beyond which nothing higher can
be discovered in the human mind for elaborating the matter of
intuition and subjecting it to the highest unity of thought. At this
stage of our inquiry it is my duty to give an explanation of this,
the highest faculty of cognition, and I confess I find myself here
in some difficulty. Of reason, as of the understanding, there is a
merely formal, that is, logical use, in which it makes abstraction
of all content of cognition; but there is also a real use, inasmuch
as it contains in itself the source of certain conceptions and principles,
which it does not borrow either from the senses or the
understanding. The former faculty has been long defined by logicians
as the faculty of mediate conclusion in contradistinction to immediate
conclusions (consequentiae immediatae); but the nature of the
latter, which itself generates conceptions, is not to be understood
from this definition. Now as a division of reason into a logical and
a transcendental faculty presents itself here, it becomes necessary
to seek for a higher conception of this source of cognition which shall
comprehend both conceptions. In this we may expect, according to the
analogy of the conceptions of the understanding, that the logical
conception will give us the key to the transcendental, and that the
table of the functions of the former will present us with the clue
to the conceptions of reason.

In the former part of our transcendental logic, we defined the
understanding to be the faculty of rules; reason may be
distinguished from understanding as the faculty of principles.

The term principle is ambiguous, and commonly signifies merely a
cognition that may be employed as a principle, although it is not in
itself, and as regards its proper origin, entitled to the distinction.
Every general proposition, even if derived from experience by the
process of induction, may serve as the major in a syllogism; but it
is not for that reason a principle. Mathematical axioms (for example,
there can be only one straight line between two points) are general
a priori cognitions, and are therefore rightly denominated principles,
relatively to the cases which can be subsumed under them. But I cannot
for this reason say that I cognize this property of a straight line
from principles--I cognize it only in pure intuition.

Cognition from principles, then, is that cognition in which I
cognize the particular in the general by means of conceptions. Thus
every syllogism is a form of the deduction of a cognition from a
principle. For the major always gives a conception, through which
everything that is subsumed under the condition thereof is cognized
according to a principle. Now as every general cognition may serve
as the major in a syllogism, and the understanding presents us with
such general a priori propositions, they may be termed principles,
in respect of their possible use.

But if we consider these principles of the pure understanding in
relation to their origin, we shall find them to be anything rather
than cognitions from conceptions. For they would not even be
possible a priori, if we could not rely on the assistance of pure
intuition (in mathematics), or on that of the conditions of a possible
experience. That everything that happens has a cause, cannot be
concluded from the general conception of that which happens; on the
contrary the principle of causality instructs us as to the mode of
obtaining from that which happens a determinate empirical conception.

Synthetical cognitions from conceptions the understanding cannot
supply, and they alone are entitled to be called principles. At the
same time, all general propositions may be termed comparative

It has been a long-cherished wish--that (who knows how late), may
one day, be happily accomplished--that the principles of the endless
variety of civil laws should be investigated and exposed; for in
this way alone can we find the secret of simplifying legislation.
But in this case, laws are nothing more than limitations of our
freedom upon conditions under which it subsists in perfect harmony
with itself; they consequently have for their object that which is
completely our own work, and of which we ourselves may be the cause
by means of these conceptions. But how objects as things in themselves-
how the nature of things is subordinated to principles and is to be
determined, according to conceptions, is a question which it seems
well nigh impossible to answer. Be this, however, as it may--for on
this point our investigation is yet to be made--it is at least
manifest from what we have said that cognition from principles is
something very different from cognition by means of the understanding,
which may indeed precede other cognitions in the form of a
principle, but in itself--in so far as it is synthetical--is neither
based upon mere thought, nor contains a general proposition drawn from
conceptions alone.

The understanding may be a faculty for the production of unity of
phenomena by virtue of rules; the reason is a faculty for the
production of unity of rules (of the understanding) under
principles. Reason, therefore, never applies directly to experience,
or to any sensuous object; its object is, on the contrary, the
understanding, to the manifold cognition of which it gives a unity
a priori by means of conceptions--a unity which may be called rational
unity, and which is of a nature very different from that of the
unity produced by the understanding.

The above is the general conception of the faculty of reason, in
so far as it has been possible to make it comprehensible in the
absence of examples. These will be given in the sequel.


A distinction is commonly made between that which is immediately
cognized and that which is inferred or concluded. That in a figure
which is bounded by three straight lines there are three angles, is
an immediate cognition; but that these angles are together equal to
two right angles, is an inference or conclusion. Now, as we are constantly
employing this mode of thought and have thus become quite accustomed
to it, we no longer remark the above distinction, and, as in the
case of the so-called deceptions of sense, consider as immediately
perceived, what has really been inferred. In every reasoning or
syllogism, there is a fundamental proposition, afterwards a second
drawn from it, and finally the conclusion, which connects the truth
in the first with the truth in the second--and that infallibly. If
the judgement concluded is so contained in the first proposition that
it can be deduced from it without the meditation of a third notion,
the conclusion is called immediate (consequentia immediata); I prefer
the term conclusion of the understanding. But if, in addition to the
fundamental cognition, a second judgement is necessary for the
production of the conclusion, it is called a conclusion of the reason.
In the proposition: All men are mortal, are contained the
propositions: Some men are mortal, Nothing that is not mortal is a
man, and these are therefore immediate conclusions from the first.
On the other hand, the proposition: all the learned are mortal, is
not contained in the main proposition (for the conception of a learned
man does not occur in it), and it can be deduced from the main proposition
only by means of a mediating judgement.

In every syllogism I first cogitate a rule (the major) by means of
the understanding. In the next place I subsume a cognition under the
condition of the rule (and this is the minor) by means of the
judgement. And finally I determine my cognition by means of the
predicate of the rule (this is the conclusio), consequently, I
determine it a priori by means of the reason. The relations,
therefore, which the major proposition, as the rule, represents
between a cognition and its condition, constitute the different
kinds of syllogisms. These are just threefold--analogously with all
judgements, in so far as they differ in the mode of expressing the
relation of a cognition in the understanding--namely, categorical,
hypothetical, and disjunctive.

When as often happens, the conclusion is a judgement which may
follow from other given judgements, through which a perfectly
different object is cogitated, I endeavour to discover in the
understanding whether the assertion in this conclusion does not
stand under certain conditions according to a general rule. If I
find such a condition, and if the object mentioned in the conclusion
can be subsumed under the given condition, then this conclusion
follows from a rule which is also valid for other objects of
cognition. From this we see that reason endeavours to subject the
great variety of the cognitions of the understanding to the smallest
possible number of principles (general conditions), and thus to
produce in it the highest unity.


Can we isolate reason, and, if so, is it in this case a peculiar
source of conceptions and judgements which spring from it alone, and
through which it can be applied to objects; or is it merely a
subordinate faculty, whose duty it is to give a certain form to
given cognitions--a form which is called logical, and through which
the cognitions of the understanding are subordinated to each other,
and lower rules to higher (those, to wit, whose condition comprises
in its sphere the condition of the others), in so far as this can be
done by comparison? This is the question which we have at present to
answer. Manifold variety of rules and unity of principles is a
requirement of reason, for the purpose of bringing the understanding
into complete accordance with itself, just as understanding subjects
the manifold content of intuition to conceptions, and thereby
introduces connection into it. But this principle prescribes no law
to objects, and does not contain any ground of the possibility of
cognizing or of determining them as such, but is merely a subjective
law for the proper arrangement of the content of the understanding.
The purpose of this law is, by a comparison of the conceptions of
the understanding, to reduce them to the smallest possible number,
although, at the same time, it does not justify us in demanding from
objects themselves such a uniformity as might contribute to the
convenience and the enlargement of the sphere of the understanding,
or in expecting that it will itself thus receive from them objective
validity. In one word, the question is: "does reason in itself, that
is, does pure reason contain a priori synthetical principles and
rules, and what are those principles?"

The formal and logical procedure of reason in syllogisms gives us
sufficient information in regard to the ground on which the
transcendental principle of reason in its pure synthetical cognition
will rest.

1. Reason, as observed in the syllogistic process, is not applicable
to intuitions, for the purpose of subjecting them to rules--for this
is the province of the understanding with its categories--but to
conceptions and judgements. If pure reason does apply to objects and
the intuition of them, it does so not immediately, but mediately-
through the understanding and its judgements, which have a direct
relation to the senses and their intuition, for the purpose of
determining their objects. The unity of reason is therefore not the
unity of a possible experience, but is essentially different from this
unity, which is that of the understanding. That everything which
happens has a cause, is not a principle cognized and prescribed by
reason. This principle makes the unity of experience possible and
borrows nothing from reason, which, without a reference to possible
experience, could never have produced by means of mere conceptions
any such synthetical unity.

2. Reason, in its logical use, endeavours to discover the general
condition of its judgement (the conclusion), and a syllogism is itself
nothing but a judgement by means of the subsumption of its condition
under a general rule (the major). Now as this rule may itself be
subjected to the same process of reason, and thus the condition of
the condition be sought (by means of a prosyllogism) as long as the
process can be continued, it is very manifest that the peculiar
principle of reason in its logical use is to find for the
conditioned cognition of the understanding the unconditioned whereby
the unity of the former is completed.

But this logical maxim cannot be a principle of pure reason,
unless we admit that, if the conditioned is given, the whole series
of conditions subordinated to one another--a series which is consequently
itself unconditioned--is also given, that is, contained in the
object and its connection.

But this principle of pure reason is evidently synthetical; for,
analytically, the conditioned certainly relates to some condition,
but not to the unconditioned. From this principle also there must
originate different synthetical propositions, of which the pure
understanding is perfectly ignorant, for it has to do only with
objects of a possible experience, the cognition and synthesis of which
is always conditioned. The unconditioned, if it does really exist,
must be especially considered in regard to the determinations which
distinguish it from whatever is conditioned, and will thus afford us
material for many a priori synthetical propositions.

The principles resulting from this highest principle of pure
reason will, however, be transcendent in relation to phenomena, that
is to say, it will be impossible to make any adequate empirical use
of this principle. It is therefore completely different from all
principles of the understanding, the use made of which is entirely
immanent, their object and purpose being merely the possibility of
experience. Now our duty in the transcendental dialectic is as
follows. To discover whether the principle that the series of
conditions (in the synthesis of phenomena, or of thought in general)
extends to the unconditioned is objectively true, or not; what
consequences result therefrom affecting the empirical use of the
understanding, or rather whether there exists any such objectively
valid proposition of reason, and whether it is not, on the contrary,
a merely logical precept which directs us to ascend perpetually to
still higher conditions, to approach completeness in the series of
them, and thus to introduce into our cognition the highest possible
unity of reason. We must ascertain, I say, whether this requirement
of reason has not been regarded, by a misunderstanding, as a transcendental
principle of pure reason, which postulates a thorough completeness
in the series of conditions in objects themselves. We must show,
moreover, the misconceptions and illusions that intrude into
syllogisms, the major proposition of which pure reason has supplied--a
proposition which has perhaps more of the character of a petitio
than of a postulatum--and that proceed from experience upwards to
its conditions. The solution of these problems is our task in
transcendental dialectic, which we are about to expose even at its
source, that lies deep in human reason. We shall divide it into two
parts, the first of which will treat of the transcendent conceptions
of pure reason, the second of transcendent and dialectical syllogisms.



The conceptions of pure reason--we do not here speak of the
possibility of them--are not obtained by reflection, but by
inference or conclusion. The conceptions of understanding are also
cogitated a priori antecedently to experience, and render it possible;
but they contain nothing but the unity of reflection upon phenomena,
in so far as these must necessarily belong to a possible empirical
consciousness. Through them alone are cognition and the
determination of an object possible. It is from them, accordingly,
that we receive material for reasoning, and antecedently to them we
possess no a priori conceptions of objects from which they might be
deduced, On the other hand, the sole basis of their objective
reality consists in the necessity imposed on them, as containing the
intellectual form of all experience, of restricting their
application and influence to the sphere of experience.

But the term, conception of reason, or rational conception, itself
indicates that it does not confine itself within the limits of
experience, because its object-matter is a cognition, of which every
empirical cognition is but a part--nay, the whole of possible
experience may be itself but a part of it--a cognition to which no
actual experience ever fully attains, although it does always
pertain to it. The aim of rational conceptions is the comprehension,
as that of the conceptions of understanding is the understanding of
perceptions. If they contain the unconditioned, they relate to that
to which all experience is subordinate, but which is never itself an
object of experience--that towards which reason tends in all its
conclusions from experience, and by the standard of which it estimates
the degree of their empirical use, but which is never itself an
element in an empirical synthesis. If, notwithstanding, such
conceptions possess objective validity, they may be called conceptus
ratiocinati (conceptions legitimately concluded); in cases where
they do not, they have been admitted on account of having the
appearance of being correctly concluded, and may be called conceptus
ratiocinantes (sophistical conceptions). But as this can only be
sufficiently demonstrated in that part of our treatise which relates
to the dialectical conclusions of reason, we shall omit any
consideration of it in this place. As we called the pure conceptions
of the understanding categories, we shall also distinguish those of
pure reason by a new name and call them transcendental ideas. These
terms, however, we must in the first place explain and justify.

SECTION I--Of Ideas in General.

Despite the great wealth of words which European languages
possess, the thinker finds himself often at a loss for an expression
exactly suited to his conception, for want of which he is unable to
make himself intelligible either to others or to himself. To coin
new words is a pretension to legislation in language which is seldom
successful; and, before recourse is taken to so desperate an
expedient, it is advisable to examine the dead and learned
languages, with the hope and the probability that we may there meet
with some adequate expression of the notion we have in our minds. In
this case, even if the original meaning of the word has become
somewhat uncertain, from carelessness or want of caution on the part
of the authors of it, it is always better to adhere to and confirm
its proper meaning--even although it may be doubtful whether it was
formerly used in exactly this sense--than to make our labour vain by
want of sufficient care to render ourselves intelligible.

For this reason, when it happens that there exists only a single
word to express a certain conception, and this word, in its usual
acceptation, is thoroughly adequate to the conception, the accurate
distinction of which from related conceptions is of great
importance, we ought not to employ the expression improvidently, or,
for the sake of variety and elegance of style, use it as a synonym
for other cognate words. It is our duty, on the contrary, carefully
to preserve its peculiar signification, as otherwise it easily happens
that when the attention of the reader is no longer particularly
attracted to the expression, and it is lost amid the multitude of
other words of very different import, the thought which it conveyed,
and which it alone conveyed, is lost with it.

Plato employed the expression idea in a way that plainly showed he
meant by it something which is never derived from the senses, but
which far transcends even the conceptions of the understanding (with
which Aristotle occupied himself), inasmuch as in experience nothing
perfectly corresponding to them could be found. Ideas are, according
to him, archetypes of things themselves, and not merely keys to
possible experiences, like the categories. In his view they flow
from the highest reason, by which they have been imparted to human
reason, which, however, exists no longer in its original state, but
is obliged with great labour to recall by reminiscence--which is called
philosophy--the old but now sadly obscured ideas. I will not here
enter upon any literary investigation of the sense which this
sublime philosopher attached to this expression. I shall content
myself with remarking that it is nothing unusual, in common
conversation as well as in written works, by comparing the thoughts
which an author has delivered upon a subject, to understand him better
than he understood himself inasmuch as he may not have sufficiently
determined his conception, and thus have sometimes spoken, nay even
thought, in opposition to his own opinions.

Plato perceived very clearly that our faculty of cognition has the
feeling of a much higher vocation than that of merely spelling out
phenomena according to synthetical unity, for the purpose of being
able to read them as experience, and that our reason naturally
raises itself to cognitions far too elevated to admit of the
possibility of an object given by experience corresponding to them-
cognitions which are nevertheless real, and are not mere phantoms of
the brain.

This philosopher found his ideas especially in all that is
practical,* that is, which rests upon freedom, which in its turn ranks
under cognitions that are the peculiar product of reason. He who would
derive from experience the conceptions of virtue, who would make (as
many have really done) that, which at best can but serve as an
imperfectly illustrative example, a model for or the formation of a
perfectly adequate idea on the subject, would in fact transform virtue
into a nonentity changeable according to time and circumstance and
utterly incapable of being employed as a rule. On the contrary,
every one is conscious that, when any one is held up to him as a model
of virtue, he compares this so-called model with the true original
which he possesses in his own mind and values him according to this
standard. But this standard is the idea of virtue, in relation to
which all possible objects of experience are indeed serviceable as
examples--proofs of the practicability in a certain degree of that
which the conception of virtue demands--but certainly not as
archetypes. That the actions of man will never be in perfect
accordance with all the requirements of the pure ideas of reason, does
not prove the thought to be chimerical. For only through this idea
are all judgements as to moral merit or demerit possible; it
consequently lies at the foundation of every approach to moral
perfection, however far removed from it the obstacles in human nature-
indeterminable as to degree--may keep us.

[*Footnote: He certainly extended the application of his conception
to speculative cognitions also, provided they were given pure and
completely a priori, nay, even to mathematics, although this science
cannot possess an object otherwhere than in Possible experience. I
cannot follow him in this, and as little can I follow him in his
mystical deduction of these ideas, or in his hypostatization of
them; although, in truth, the elevated and exaggerated language
which he employed in describing them is quite capable of an
interpretation more subdued and more in accordance with fact and the
nature of things.]

The Platonic Republic has become proverbial as an example--and a
striking one--of imaginary perfection, such as can exist only in the
brain of the idle thinker; and Brucker ridicules the philosopher for
maintaining that a prince can never govern well, unless he is
participant in the ideas. But we should do better to follow up this
thought and, where this admirable thinker leaves us without
assistance, employ new efforts to place it in clearer light, rather
than carelessly fling it aside as useless, under the very miserable
and pernicious pretext of impracticability. A constitution of the
greatest possible human freedom according to laws, by which the
liberty of every individual can consist with the liberty of every
other (not of the greatest possible happiness, for this follows
necessarily from the former), is, to say the least, a necessary
idea, which must be placed at the foundation not only of the first
plan of the constitution of a state, but of all its laws. And, in
this, it not necessary at the outset to take account of the
obstacles which lie in our way--obstacles which perhaps do not
necessarily arise from the character of human nature, but rather
from the previous neglect of true ideas in legislation. For there is
nothing more pernicious and more unworthy of a philosopher, than the
vulgar appeal to a so-called adverse experience, which indeed would
not have existed, if those institutions had been established at the
proper time and in accordance with ideas; while, instead of this,
conceptions, crude for the very reason that they have been drawn
from experience, have marred and frustrated all our better views and
intentions. The more legislation and government are in harmony with
this idea, the more rare do punishments become and thus it is quite
reasonable to maintain, as Plato did, that in a perfect state no
punishments at all would be necessary. Now although a perfect state
may never exist, the idea is not on that account the less just,
which holds up this maximum as the archetype or standard of a
constitution, in order to bring legislative government always nearer
and nearer to the greatest possible perfection. For at what precise
degree human nature must stop in its progress, and how wide must be
the chasm which must necessarily exist between the idea and its
realization, are problems which no one can or ought to determine-
and for this reason, that it is the destination of freedom to overstep
all assigned limits between itself and the idea.

But not only in that wherein human reason is a real causal agent and
where ideas are operative causes (of actions and their objects),
that is to say, in the region of ethics, but also in regard to
nature herself, Plato saw clear proofs of an origin from ideas. A
plant, and animal, the regular order of nature--probably also the
disposition of the whole universe--give manifest evidence that they
are possible only by means of and according to ideas; that, indeed,
no one creature, under the individual conditions of its existence,
perfectly harmonizes with the idea of the most perfect of its kind-
just as little as man with the idea of humanity, which nevertheless
he bears in his soul as the archetypal standard of his actions; that,
notwithstanding, these ideas are in the highest sense individually,
unchangeably, and completely determined, and are the original causes
of things; and that the totality of connected objects in the
universe is alone fully adequate to that idea. Setting aside the
exaggerations of expression in the writings of this philosopher, the
mental power exhibited in this ascent from the ectypal mode of
regarding the physical world to the architectonic connection thereof
according to ends, that is, ideas, is an effort which deserves
imitation and claims respect. But as regards the principles of ethics,
of legislation, and of religion, spheres in which ideas alone render
experience possible, although they never attain to full expression
therein, he has vindicated for himself a position of peculiar merit,
which is not appreciated only because it is judged by the very
empirical rules, the validity of which as principles is destroyed by
ideas. For as regards nature, experience presents us with rules and
is the source of truth, but in relation to ethical laws experience
is the parent of illusion, and it is in the highest degree reprehensible
to limit or to deduce the laws which dictate what I ought to do, from
what is done.

We must, however, omit the consideration of these important
subjects, the development of which is in reality the peculiar duty
and dignity of philosophy, and confine ourselves for the present to
the more humble but not less useful task of preparing a firm foundation
for those majestic edifices of moral science. For this foundation
has been hitherto insecure from the many subterranean passages which
reason in its confident but vain search for treasures has made in
all directions. Our present duty is to make ourselves perfectly
acquainted with the transcendental use made of pure reason, its
principles and ideas, that we may be able properly to determine and
value its influence and real worth. But before bringing these
introductory remarks to a close, I beg those who really have
philosophy at heart--and their number is but small--if they shall find
themselves convinced by the considerations following as well as by
those above, to exert themselves to preserve to the expression idea
its original signification, and to take care that it be not lost among
those other expressions by which all sorts of representations are
loosely designated--that the interests of science may not thereby
suffer. We are in no want of words to denominate adequately every mode
of representation, without the necessity of encroaching upon terms
which are proper to others. The following is a graduated list of them.
The genus is representation in general (representatio). Under it
stands representation with consciousness (perceptio). A perception
which relates solely to the subject as a modification of its state,
is a sensation (sensatio), an objective perception is a cognition
(cognitio). A cognition is either an intuition or a conception
(intuitus vel conceptus). The former has an immediate relation to
the object and is singular and individual; the latter has but a
mediate relation, by means of a characteristic mark which may be
common to several things. A conception is either empirical or pure.
A pure conception, in so far as it has its origin in the understanding
alone, and is not the conception of a pure sensuous image, is called
notio. A conception formed from notions, which transcends the
possibility of experience, is an idea, or a conception of reason. To
one who has accustomed himself to these distinctions, it must be quite
intolerable to hear the representation of the colour red called an
idea. It ought not even to be called a notion or conception of

SECTION II. Of Transcendental Ideas.

Transcendental analytic showed us how the mere logical form of our
cognition can contain the origin of pure conceptions a priori,
conceptions which represent objects antecedently to all experience,
or rather, indicate the synthetical unity which alone renders possible
an empirical cognition of objects. The form of judgements--converted
into a conception of the synthesis of intuitions--produced the categories
which direct the employment of the understanding in experience. This
consideration warrants us to expect that the form of syllogisms,
when applied to synthetical unity of intuitions, following the rule
of the categories, will contain the origin of particular a priori
conceptions, which we may call pure conceptions of reason or
transcendental ideas, and which will determine the use of the
understanding in the totality of experience according to principles.

The function of reason in arguments consists in the universality
of a cognition according to conceptions, and the syllogism itself is
a judgement which is determined a priori in the whole extent of its
condition. The proposition: "Caius is mortal," is one which may be
obtained from experience by the aid of the understanding alone; but
my wish is to find a conception which contains the condition under
which the predicate of this judgement is given--in this case, the
conception of man--and after subsuming under this condition, taken
in its whole extent (all men are mortal), I determine according to
it the cognition of the object thought, and say: "Caius is mortal."

Hence, in the conclusion of a syllogism we restrict a predicate to
a certain object, after having thought it in the major in its whole
extent under a certain condition. This complete quantity of the extent
in relation to such a condition is called universality
(universalitas). To this corresponds totality (universitas) of
conditions in the synthesis of intuitions. The transcendental
conception of reason is therefore nothing else than the conception
of the totality of the conditions of a given conditioned. Now as the
unconditioned alone renders possible totality of conditions, and,
conversely, the totality of conditions is itself always unconditioned;
a pure rational conception in general can be defined and explained
by means of the conception of the unconditioned, in so far as it
contains a basis for the synthesis of the conditioned.

To the number of modes of relation which the understanding cogitates
by means of the categories, the number of pure rational conceptions
will correspond. We must therefore seek for, first, an unconditioned
of the categorical synthesis in a subject; secondly, of the
hypothetical synthesis of the members of a series; thirdly, of the
disjunctive synthesis of parts in a system.

There are exactly the same number of modes of syllogisms, each of
which proceeds through prosyllogisms to the unconditioned--one to
the subject which cannot be employed as predicate, another to the
presupposition which supposes nothing higher than itself, and the
third to an aggregate of the members of the complete division of a
conception. Hence the pure rational conceptions of totality in the
synthesis of conditions have a necessary foundation in the nature of
human reason--at least as modes of elevating the unity of the
understanding to the unconditioned. They may have no valid
application, corresponding to their transcendental employment, in
concreto, and be thus of no greater utility than to direct the
understanding how, while extending them as widely as possible, to
maintain its exercise and application in perfect consistence and

But, while speaking here of the totality of conditions and of the
unconditioned as the common title of all conceptions of reason, we
again light upon an expression which we find it impossible to dispense
with, and which nevertheless, owing to the ambiguity attaching to it
from long abuse, we cannot employ with safety. The word absolute is
one of the few words which, in its original signification, was
perfectly adequate to the conception it was intended to convey--a
conception which no other word in the same language exactly suits,
and the loss--or, which is the same thing, the incautious and loose
employment--of which must be followed by the loss of the conception
itself. And, as it is a conception which occupies much of the
attention of reason, its loss would be greatly to the detriment of
all transcendental philosophy. The word absolute is at present
frequently used to denote that something can be predicated of a
thing considered in itself and intrinsically. In this sense absolutely
possible would signify that which is possible in itself (interne)-
which is, in fact, the least that one can predicate of an object. On
the other hand, it is sometimes employed to indicate that a thing is
valid in all respects--for example, absolute sovereignty. Absolutely
possible would in this sense signify that which is possible in all
relations and in every respect; and this is the most that can be
predicated of the possibility of a thing. Now these significations
do in truth frequently coincide. Thus, for example, that which is
intrinsically impossible, is also impossible in all relations, that
is, absolutely impossible. But in most cases they differ from each
other toto caelo, and I can by no means conclude that, because a thing
is in itself possible, it is also possible in all relations, and
therefore absolutely. Nay, more, I shall in the sequel show that
absolute necessity does not by any means depend on internal necessity,
and that, therefore, it must not be considered as synonymous with
it. Of an opposite which is intrinsically impossible, we may affirm
that it is in all respects impossible, and that, consequently, the
thing itself, of which this is the opposite, is absolutely
necessary; but I cannot reason conversely and say, the opposite of
that which is absolutely necessary is intrinsically impossible, that
is, that the absolute necessity of things is an internal necessity.
For this internal necessity is in certain cases a mere empty word with
which the least conception cannot be connected, while the conception
of the necessity of a thing in all relations possesses very peculiar
determinations. Now as the loss of a conception of great utility in
speculative science cannot be a matter of indifference to the
philosopher, I trust that the proper determination and careful
preservation of the expression on which the conception depends will
likewise be not indifferent to him.

In this enlarged signification, then, shall I employ the word
absolute, in opposition to that which is valid only in some particular
respect; for the latter is restricted by conditions, the former is
valid without any restriction whatever.

Now the transcendental conception of reason has for its object
nothing else than absolute totality in the synthesis of conditions
and does not rest satisfied till it has attained to the absolutely,
that is, in all respects and relations, unconditioned. For pure reason
leaves to the understanding everything that immediately relates to
the object of intuition or rather to their synthesis in imagination.
The former restricts itself to the absolute totality in the employment
of the conceptions of the understanding and aims at carrying out the
synthetical unity which is cogitated in the category, even to the
unconditioned. This unity may hence be called the rational unity of
phenomena, as the other, which the category expresses, may be termed
the unity of the understanding. Reason, therefore, has an immediate
relation to the use of the understanding, not indeed in so far as
the latter contains the ground of possible experience (for the
conception of the absolute totality of conditions is not a
conception that can be employed in experience, because no experience
is unconditioned), but solely for the purpose of directing it to a
certain unity, of which the understanding has no conception, and the
aim of which is to collect into an absolute whole all acts of the
understanding. Hence the objective employment of the pure
conceptions of reason is always transcendent, while that of the pure
conceptions of the understanding must, according to their nature, be
always immanent, inasmuch as they are limited to possible experience.

I understand by idea a necessary conception of reason, to which no
corresponding object can be discovered in the world of sense.
Accordingly, the pure conceptions of reason at present under
consideration are transcendental ideas. They are conceptions of pure
reason, for they regard all empirical cognition as determined by means
of an absolute totality of conditions. They are not mere fictions,
but natural and necessary products of reason, and have hence a necessary
relation to the whole sphere of the exercise of the understanding.
And, finally, they are transcendent, and overstep the limits of all
experiences, in which, consequently, no object can ever be presented
that would be perfectly adequate to a transcendental idea. When we
use the word idea, we say, as regards its object (an object of the
pure understanding), a great deal, but as regards its subject (that
is, in respect of its reality under conditions of experience), exceedingly
little, because the idea, as the conception of a maximum, can never
be completely and adequately presented in concreto. Now, as in the
merely speculative employment of reason the latter is properly the
sole aim, and as in this case the approximation to a conception, which
is never attained in practice, is the same thing as if the conception
were non-existent--it is commonly said of the conception of this kind,
"it is only an idea." So we might very well say, "the absolute
totality of all phenomena is only an idea," for, as we never can
present an adequate representation of it, it remains for us a
problem incapable of solution. On the other hand, as in the
practical use of the understanding we have only to do with action
and practice according to rules, an idea of pure reason can always
be given really in concreto, although only partially, nay, it is the
indispensable condition of all practical employment of reason. The
practice or execution of the idea is always limited and defective,
but nevertheless within indeterminable boundaries, consequently always
under the influence of the conception of an absolute perfection. And
thus the practical idea is always in the highest degree fruitful,
and in relation to real actions indispensably necessary. In the
idea, pure reason possesses even causality and the power of
producing that which its conception contains. Hence we cannot say of
wisdom, in a disparaging way, "it is only an idea." For, for the
very reason that it is the idea of the necessary unity of all possible
aims, it must be for all practical exertions and endeavours the
primitive condition and rule--a rule which, if not constitutive, is
at least limitative.

Now, although we must say of the transcendental conceptions of
reason, "they are only ideas," we must not, on this account, look upon
them as superfluous and nugatory. For, although no object can be
determined by them, they can be of great utility, unobserved and at
the basis of the edifice of the understanding, as the canon for its
extended and self-consistent exercise--a canon which, indeed, does
not enable it to cognize more in an object than it would cognize by
the help of its own conceptions, but which guides it more securely
in its cognition. Not to mention that they perhaps render possible
a transition from our conceptions of nature and the non-ego to the
practical conceptions, and thus produce for even ethical ideas
keeping, so to speak, and connection with the speculative cognitions
of reason. The explication of all this must be looked for in the

But setting aside, in conformity with our original purpose, the
consideration of the practical ideas, we proceed to contemplate reason
in its speculative use alone, nay, in a still more restricted
sphere, to wit, in the transcendental use; and here must strike into
the same path which we followed in our deduction of the categories.
That is to say, we shall consider the logical form of the cognition
of reason, that we may see whether reason may not be thereby a source
of conceptions which enables us to regard objects in themselves as
determined synthetically a priori, in relation to one or other of

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