THE ANALOGIES OF EXPERIENCE
Each of the three categories of relation, i. e. those of substance and
accident, of cause and effect, and of interaction between agent and
patient involves, according to Kant, a special principle, and these
special principles he calls 'analogies of experience'. They are stated
thus:[1] (1) In all changes of phenomena the substance is permanent,
and its quantity in nature is neither increased nor diminished. (2)
All changes take place according to the law of the connexion of cause
and effect. (3) All substances, so far as they can be perceived in
space as coexistent, are in complete interaction. The justification of
the term _analogy_ of experience is as follows. In mathematics an
analogy is a formula which asserts the equality of two _quantitative_
relations, and is such that, if three of the terms are given, we can
discover the fourth, e. g. if we know that _a_ : _b_ = _c_ : _d_, and
that _a_ = 2, _b_ = 4, _c_ = 6 we can discover that _d_ = 12. But in
philosophy an analogy is the assertion of the equality of two
_qualitative_ relations and is such that, if three of the terms are
given, we can discover, not the fourth, but only the relation of the
third to the fourth, though at the same time we are furnished with a
clue whereby to search for the fourth in experience. In this
philosophical sense, the principles involved in the categories of
relation are analogies. For instance, the principles of causality can
be stated in the form 'Any known event _X_ is to _some other_ event
_Y_, whatever it be, as effect to cause'; so stated, it clearly
informs us not of the character of _Y_ but only of the fact that there
must be a _Y_, i. e. a necessary antecedent, though at the same time
this knowledge enables us to search in experience for the special
character of _Y_.
[1] The formulation of them in the first edition is slightly
different.
The principles to be established relate to the two kinds of temporal
relation apprehended in the world of nature, viz. coexistence and
succession. The _method_ of proof, which is to be gathered from the
proofs themselves rather than from Kant's general remarks[2] on the
subject, is the same in each case. Kant expressly rejects any proof
which is 'dogmatical' or 'from conceptions', e. g. any attempt to show
that the very conception of change presupposes the thought of an
identical subject of change.[3] The proof is transcendental in
character, i. e. it argues that the principle to be established is a
condition of the possibility of _apprehending_ the temporal relation
in question, e. g. that the existence of a permanent subject of change
is presupposed in any _apprehension_ of change. It assumes that we
become aware of sequences and coexistences in the world of nature by a
process which begins with a succession of mere perceptions, i. e.
perceptions which are so far not the perceptions of a sequence or of a
coexistence or indeed of anything;[4] and it seeks to show that this
process involves an appeal to one of the principles in question--the
particular principle involved depending on the temporal relation
apprehended--and consequently, that since we do apprehend this
temporal relation, which, as belonging to the world of nature, must be
distinct from any temporal relation of our perceptions, the principle
appealed to is valid.
[2] B. 218-24, M. 132-6; and B. 262-5, M. 159-61.
[3] B. 263-4, M. 160-1; B. 289, M. 174-5.
[4] This assumption is of course analogous to the assumption
which underlies the _Transcendental Deduction of the
Categories_, that knowledge begins with the successive
origination in us of isolated data of sense.
The proof of the first analogy is given somewhat differently in the
first edition, and in a passage added in the second. The earlier
version, which is a better expression of the attitude underlying
Kant's general remarks on the analogy, is as follows:
"Our _apprehension_ of the manifold of a phenomenon is always
successive, and is therefore always changing. By it alone, therefore,
we can never determine whether this manifold, as an object of
experience, is coexistent or successive, unless there lies at the base
of it something that exists _always_, that is, something _enduring_
and _permanent_, of which all succession and coexistence are nothing
but so many ways (_modi_ of time) in which the permanent exists. Only
in the permanent, then, are time relations possible (for simultaneity
and succession are the only relations in time); i. e. the permanent is
the _substratum_ of the empirical representation of time itself, in
which alone all time-determination is possible. Permanence expresses
in general time, as the persisting correlate of all existence of
phenomena, of all change, and of all concomitance.... Only through the
permanent does _existence_ in different parts of the successive series
of time gain a _quantity_ which we call _duration_. For, in mere
succession, existence is always vanishing and beginning, and never
has the least quantity. Without this permanent, then, no time
relation is possible. Now, time in itself cannot be perceived[5];
consequently this permanent in phenomena is the substratum of all
time-determination, and therefore also the condition of the
possibility of all synthetic unity of sense-perceptions, that is, of
experience, and in this permanent all existence and all change in time
can only be regarded as a mode of the existence of that which endures
and is permanent. Therefore in all phenomena the permanent is the
object itself, i. e. the substance (_phenomenon_); but all that
changes or can change belongs only to the way in which this substance
or substances exist, consequently to their determinations."[6]
"Accordingly since substance cannot change in existence, its quantity
in nature can neither be increased nor diminished."[7] The argument
becomes plainer if it be realized that in the interval between the two
editions, Kant came to think that the permanent in question was matter
or bodies in space.[8] "We find that in order to give something
_permanent_ in perception corresponding to the conception of
_substance_ (and thereby to exhibit the objective reality of this
conception), we need a perception _in space_ (of matter), because
space alone has permanent determinations, while time, and consequently
everything which is in the internal sense, is continually flowing."[9]
[5] _Wahrgenommen._
[6] A. 182-4 and B. 225-7, M. 137-8. This formulation of the
conclusion is adapted only to the form in which the first
analogy is stated in the first edition, viz. "All phenomena
contain the permanent (_substance_) as the object itself and
the changeable as its mere determination, i. e. as a way
in which the object exists." Hence a sentence from the
conclusion of the proof added in the second edition is quoted
to elucidate Kant's meaning; its doctrine is as legitimate a
conclusion of the argument given in the first edition as of
that peculiar to the second.
[7] B. 225, M. 137.
[8] Cf. Caird, i. 541-2.
[9] B. 291, M. 176 (in 2nd ed. only). Cf. B. 277 fin.-278
init., M. 168 (in 2nd ed. only).
Kant's thought appears to be as follows: 'Our apprehension of the
manifold consists of a series of successive acts in which we apprehend
its elements one by one and in isolation. This apprehension,
therefore, does not enable us to determine that its elements are
temporally related either as successive or as coexistent.[10] In order
to determine this, we must apprehend the elements of the manifold as
related to something permanent. For a succession proper, i. e. a
change, is a succession of states or determinations of something
permanent or unchanging. A mere succession which is not a succession
of states of something which remains identical is an unconnected
series of endings and beginnings, and with respect to it, 'duration',
which has meaning with regard to changes, i. e. successions proper,
has no meaning at all. Similarly, coexistence is a coexistence of
states of two permanents. Hence, to apprehend elements of the manifold
as successive or coexistent, we must apprehend them in relation to a
permanent or permanents. Therefore, to apprehend a coexistence or a
succession, we must perceive something permanent. But this permanent
something cannot be time, for time cannot be perceived. It must
therefore be a permanent in phenomena; and this must be the object
itself or the substance of a phenomenon, i. e. the substratum of the
changes which it undergoes, or that of which the elements of the
manifold are states or modifications.[11] Consequently, there must be
a permanent substance of a phenomenon, and the quantity of substances
taken together must be constant.'
[10] The account of the first analogy as a whole makes it
necessary to think that Kant in the first two sentences of
the proof quoted does not mean exactly what he says, what he
says being due to a desire to secure conformity with his
treatment of the second and third analogies. What he _says_
suggests (1) that he is about to discuss the implications,
not of the process by which we come to apprehend the manifold
as temporally related in one of the two ways possible, i. e.
either as successive or as coexistent, but of the process by
which we decide whether the relation of the manifold which we
already know to be temporal is that of succession or that of
coexistence, and (2) that the necessity for this process is
due to the fact that our _apprehension_ of the manifold is
always successive. The context, however, refutes both
suggestions, and in any case it is the special function of
the processes which involve the second and third analogies to
determine the relations of the manifold as that of succession
and that of coexistence respectively.
[11] Cf. B. 225, M. 137 (first half).
Now, if Kant's thought has been here represented fairly, it is open to
the following comments. In the first place, even if his position be
right in the main, Kant should not introduce the thought of the
_quantity_ of substance, and speak of the quantity as constant. For he
thereby implies that in a plurality of substances--if such a plurality
can in the end be admitted--there may be total extinction of, or
partial loss in, some, if only there be a corresponding compensation
in others; whereas such extinction and creation would be inconsistent
with the nature of a substance.[12] Even Kant himself speaks of having
established the impossibility of the origin and extinction of
substance.[13]
[12] I owe this comment to Professor Cook Wilson.
[13] B. 232-3, M. 141 fin.
In the second place, it is impossible to see how it can be legitimate
for Kant to speak of a permanent substratum of change at all.[14] For
phenomena or appearances neither are nor imply the substratum of which
Kant is thinking. They might be held to imply ourselves as the
identical substratum of which they are successive states, but this
view would be irrelevant to, if not inconsistent with, Kant's
doctrine. It is all very well to _say_ that the substratum is to be
found in matter, i. e. in bodies in space,[15] but the assertion is
incompatible with the phenomenal character of the world; for the
sensations or appearances produced in us by the thing in itself cannot
be successive states of bodies in space. In the third place, in spite
of Kant's protests against any proof which is 'dogmatical' or 'from
conceptions', such a proof really forms the basis of his thought. For
if the argument is to proceed not from the nature of change as such
but from the possibility of perceiving change, it must not take into
account any implications of the possibility of perceiving change which
rest upon implications of the nature of change as such. Yet this is
what the argument does. For the reason really given for the view that
the apprehension of change involves the apprehension of the manifold
as related to a permanent substratum is that a change, as such,
implies a permanent substratum. It is only because change is held to
imply a substratum that we are said to be able to apprehend a change
only in relation to a substratum. Moreover, shortly afterwards, Kant,
apparently without realizing what he is doing, actually uses what is,
on the very face of it, the dogmatic method, and in accordance with it
develops the implications of the perception of change. "Upon this
permanence is based the justification of the conception of _change_.
Coming into being and perishing are not changes of that which comes to
be or perishes. Change is but a mode of existence, which follows on
another mode of existence of the same object. Hence everything which
changes _endures_ and only its _condition changes_.... Change,
therefore, can be perceived only in substances, and absolute coming to
be or perishing, which does not concern merely a determination of the
permanent, cannot be a possible perception."[16] Surely the fact that
Kant is constrained in spite of himself to use the dogmatic method is
some indication that it is the right method. It is in reality
impossible to make any discoveries about change, or indeed about
anything, except by consideration of the nature of the thing itself;
no study of the conditions under which it can be apprehended can throw
any light upon its nature.[17] Lastly, although the supposition is not
so explicit as the corresponding supposition made in the case of the
other analogies, Kant's argument really assumes, and assumes wrongly,
the existence of a process by which, starting with the successive
apprehension of elements of the manifold in isolation, we come to
apprehend them as temporally related.
[14] The term 'permanent' is retained to conform to Kant's
language. Strictly speaking, only a state of that which
changes can be said to persist or to be permanent; for the
substratum of change is not susceptible of any temporal
predicates. Cf. p. 306.
[15] B. 291, M. 176.
[16] B. 230-1, M. 176.
[17] Cf. pp. 300-1.
The deduction of the second and third analogies argues that the
principles of causality and reciprocal action are involved
respectively in the processes by which we become aware of successions
and of coexistences in the world of nature. From this point of view it
would seem that the first analogy is a presupposition of the others,
and that the process which involves the first is presupposed by the
process which involves the others. It would seem that it is only upon
the conclusion of a process by which, beginning with the successive
apprehension of elements of the manifold in isolation, we come to
apprehend them as _either_ successive or coexistent elements in the
world of nature, that there can arise a process by which we come to
decide _whether_ the specific relation is that of succession or of
coexistence. For if the latter process can take place independently of
the former, i. e. if it can start from the successive apprehension of
the manifold, the former process will be unnecessary, and in that
case the vindication of the first analogy will be invalid. It is
necessary, however, to distinguish between Kant's nominal and his
actual procedure. Though he nominally regards the first analogy as the
presupposition of the others,[18] he really does not. For he does not
in fact treat the process which involves the validity of the first
analogy as an antecedent condition of the processes which involve the
validity of the others. On the contrary, the latter processes begin
_ab initio_ with the mere successive apprehension of the manifold,
i. e. they begin at a stage where we are not aware of any relation in
the physical world at all; and Kant, in his account of them, nowhere
urges that they involve the first analogy.[19]
[18] Cf. B. 229, M. 140; B. 232-3, M. 141-2; and Caird, i.
545 and ff.
[19] This is not disproved by B. 247-51, M. 150-2, which
involves a different conception of cause and effect.
Moreover, just because Kant does not face the difficulties involved in
the thought of a process which begins in this way until he comes to
vindicate causality, it is only when we come to this vindication that
we realize the real nature of his deduction of the analogies, and, in
particular, of that of the first.
Kant, prompted no doubt by his desire to answer Hume, treats the
principle of causality very fully. The length of the discussion,
however, is due not so much to the complication of the argument as to
Kant's desire to make his meaning unmistakable; his account consists
mainly in a repetition of what is substantially the same argument no
less than five times. Hence it will suffice to consider those passages
which best express Kant's meaning. At the same time, the prominence of
the principle of causality in Kant's theory, and in the history of
philosophy generally, and also the way in which Kant's treatment of
it reveals the true nature of his general position, makes it necessary
to consider these passages in some detail.
Hume had denied that we are justified in asserting any causal
connexion, i. e. any necessity of succession in the various events
which we perceive, but even this denial presupposed that we do
apprehend particular sequences in the world of nature, and therefore
that we succeed in distinguishing between a sequence of events in
nature and a mere sequence of perceptions, such as is also to be found
when we apprehend a coexistence of bodies in space. Kant urges, in
effect, that this denial renders it impossible to explain, as we
should be able to do, the possibility of making the distinction in
question, which even the denial itself presupposes that we make.
Holding, with Hume, that in all cases of perception what we are
directly aware of is a succession of perceptions, he contends that it
is necessary to explain how in certain cases we succeed in passing
from the knowledge of our successive perceptions to the knowledge of a
succession in what we perceive. How is it that we know, when, as we
say, we see a boat going down stream, that there is a succession in
what we perceive, and not merely a succession in our perception of it,
as is the case when, as we say, we see the parts of a house? Hume,
according to Kant, cannot answer this question; he has only the right
to say that in all cases we have a succession of perceptions; for in
reality an answer to the question will show that the acquisition of
this knowledge involves an appeal to the principle of causality.
Since, then, we do in fact, as even Hume implicitly allowed, succeed
in distinguishing between a succession in objects in nature and a
succession in our apprehension of them, the law of causality must be
true. "It is only under this presupposition (i. e. of causality) that
even the experience of an event is possible."[20]
[20] B. 240, M. 146. For the general view, cf. Caird, i.
556-61.
Kant begins[21] his proof as follows: "Our apprehension of the
manifold of a phenomenon is always successive. The representations of
the parts succeed one another. Whether they succeed one another in the
object also is a second point for reflection which is not contained in
the first."[22] But, before he can continue, the very nature of these
opening sentences compels him to consider a general problem which they
raise. The distinction referred to between a succession in our
apprehensions or representations and a succession in the object
implies an object distinct from the apprehensions or representations.
What, then, can be meant by such an object? For prima facie, if we
ignore the thing in itself as unknowable, there is no object; there
are only representations. But, in that case, what can be meant by a
succession in the object? Kant is therefore once more[23] forced to
consider the question 'What is meant by object of representations?'
although on this occasion with special reference to the meaning of a
succession in the object; and the vindication of causality is bound up
with the answer. The answer is stated thus:
[21] The preceding paragraph is an addition of the second
edition.
[22] B. 234, M. 142.
[23] Cf. A. 104-5, Mah. 198-9, and pp. 178-86 and 230-3.
"Now we may certainly give the name of object to everything, and even
to every representation, so far as we are conscious thereof; but what
this word may mean in the case of phenomena, not in so far as they (as
representations) are objects, but in so far as they only indicate an
object, is a question requiring deeper consideration. So far as they,
as representations only, are at the same time objects of
consciousness, they are not to be distinguished from apprehension,
i. e. reception into the synthesis of imagination, and we must
therefore say, 'The manifold of phenomena is always produced
successively in the mind'. If phenomena were things in themselves, no
man would be able to infer from the succession of the representations
of their manifold how this manifold is connected in the object. For
after all we have to do only with our representations; how things may
be in themselves, without regard to the representations through which
they affect us, is wholly outside the sphere of our knowledge. Now,
although phenomena are not things in themselves, and are nevertheless
the only thing which can be given to us as data for knowledge, it is
my business to show what kind of connexion in time belongs to the
manifold in phenomena themselves, while the representation of this
manifold in apprehension is always successive. Thus, for example, the
apprehension of the manifold in the phenomenon of a house which stands
before me is successive. Now arises the question, whether the manifold
of this house itself is in itself also successive, which of course no
one will grant. But, so soon as I raise my conceptions of an object to
the transcendental meaning thereof, the house is not a thing in
itself, but only a phenomenon, i. e. a representation, the
transcendental object of which is unknown. What, then, am I to
understand by the question, 'How may the manifold be connected in the
phenomenon itself (which is nevertheless nothing in itself)?' Here
that which lies in the successive apprehension is regarded as
representation, while the phenomenon which is given me, although it
is nothing more than a complex of these representations, is regarded
as the object thereof, with which my conception, drawn from the
representations of apprehension, is to agree. It is soon seen that,
since agreement of knowledge with the object is truth, we can ask here
only for the formal conditions of empirical truth, and that the
phenomenon, in opposition to the representations of apprehension, can
only be represented as the object of the same, distinct therefrom, if
it stands under a rule, which distinguishes it from every other
apprehension, and which renders necessary a mode of conjunction of the
manifold. That in the phenomenon which contains the condition of this
necessary rule of apprehension is the object."[24]
[24] B. 234-6, M. 143-4. Cf. B. 242, M. 147.
This passage is only intelligible if we realize the _impasse_ into
which Kant has been led by his doctrine that objects, i. e. realities
in the physical world, are only representations or ideas. As has
already been pointed out,[25] an apprehension is essentially
inseparable from a reality of which it is the apprehension. In other
words, an apprehension is always the apprehension of a reality, and a
reality apprehended, i. e. an object of apprehension, cannot be stated
in terms of the apprehension of it. We never confuse an apprehension
and its object; nor do we take the temporal relations which belong to
the one for the temporal relations which belong to the other, for
these relations involve different terms which are never confused, viz.
apprehensions and the objects apprehended. Now Kant, by his doctrine
of the unknowability of the thing in itself, has really deprived
himself of an object of apprehension or, in his language, of an
object of representations. For it is the thing in itself which is,
properly speaking, the object of the representations of which he is
thinking, i. e. representations of a reality in nature; and yet the
thing in itself, being on his view inapprehensible, can never be for
him an object in the proper sense, i. e. a reality apprehended. Hence
he is only able to state the fact of knowledge in terms of mere
apprehensions, or ideas, or representations--the particular name is a
matter of indifference--and consequently his efforts to recover an
object of apprehension are fruitless. As a matter of fact, these
efforts only result in the assertion that the object of
representations consists in the representations themselves related in
a certain necessary way. But this view is open to two fatal
objections. In the first place, a complex of representations is just
not an object in the proper sense, i. e. a reality apprehended. It
essentially falls on the subject side of the distinction between an
apprehension and the reality apprehended. The _complexity_ of a
complex of representations in no way divests it of the character which
it has as a complex of _representations_. In the second place, on this
view the same terms have to enter at once into two incompatible
relations. Representations have to be related successively as our
representations or apprehensions--as in fact they are related--and, at
the same time, successively or otherwise, as the case may be, as parts
of the object apprehended, viz. a reality in nature. In other words,
the same terms have to enter into both a subjective and an objective
relation, i. e. both a relation concerning us, the knowing subjects,
and a relation concerning the object which we know.[26] "A phenomenon
in opposition to the representations of apprehension can only be
represented as the object of the same, distinct therefrom, if it
stands under a rule which distinguishes it from _every other_
apprehension, and renders necessary a mode of conjunction of the
manifold."[27] A representation, however, cannot be so related by a
rule to another representation, for the rule meant relates to
realities in nature, and, however much Kant may try to maintain the
contrary, two representations, not being realities in nature, cannot
be so related. Kant is in fact only driven to treat rules of nature as
relating to representations, because there is nothing else to which he
can regard them as relating. The result is that he is unable to
justify the very distinction, the implications of which it is his aim
to discover, and he is unable to do so for the very reason which would
have rendered Hume unable to justify it. Like Hume, he is committed to
a philosophical vocabulary which makes it meaningless to speak of
relations of objects at all in distinction from relations of
apprehensions. It has been said that for Kant the road to objectivity
lay through necessity.[28] But whatever Kant may have thought, in
point of fact there is no road to objectivity, and, in particular, no
road through necessity. No necessity in the relation between two
representations can render the relation objective, i. e. a relation
between objects. No doubt the successive acts in which we come to
apprehend the world are necessarily related; we certainly do not
suppose their order to be fortuitous. Nevertheless, their relations
are not in consequence a relation of realities apprehended.
[25] pp. 133-4; cf. pp. 180 and 230-1.
[26] Cf. p. 209, note 3, and p. 233.
[27] The italics are mine.
[28] Caird, i. 557.
Kant only renders his own view plausible by treating an apprehension
or representation as if it consisted in a sensation or an appearance.
A sensation or an appearance, so far from being the apprehension of
anything, is in fact a reality which can be apprehended, of the kind
called mental. Hence it can be treated as an object, i. e. something
apprehended or presented, though not really as an object in nature. On
the other hand, from the point of view of the thing in itself it can
be treated as only an apprehension, even though it is an unsuccessful
apprehension. Thus, for Kant, there is something which can with some
plausibility be treated as an object as well as an apprehension, and
therefore as capable of standing in both a subjective and an objective
relation to other realities of the same kind.[29]
[29] Cf. pp. 137 and 231.
If we now turn to the passage under discussion, we find it easy to
vindicate the justice of the criticism that Kant, inconsistently with
the distinction which he desires to elucidate, treats the same thing
as at once the representation of an object and the object represented.
He is trying to give such an account of 'object of representations' as
will explain what is meant by a succession in an object in nature,
i. e. a phenomenon, in distinction from the succession in our
apprehension of it. In order to state this distinction at all, he has
to speak of what enters into the two successions as different. "It is
my business to show what sort of connexion in time belongs to the
_manifold_ in phenomena themselves, while the _representation_ of this
manifold in apprehension is always successive."[30] Here an element of
the manifold is distinguished from the representation of it. Yet Kant,
though he thus distinguishes them, repeatedly identifies them; in
other words, he identifies a representation with that of which it is a
representation, viz. an element in or part of the object itself. "_Our
apprehension_ of the manifold of the phenomenon is always successive.
_The representations_ of the parts succeed one another. Whether _they_
[i. e. _the representations_[31]] succeed one another _in the object_
also, is a second point for reflection.... So far as they [i. e.
phenomena], as representations only, are at the same time objects of
consciousness, they are not to be distinguished from apprehension,
i. e. reception into the synthesis of imagination, and we must
therefore say, _'The manifold of phenomena_ is always produced
successively in the mind'. If phenomena were things in themselves, no
man would be able to infer from the succession of the representations
how _this manifold_ is connected _in the object_.... The phenomenon,
in opposition to the representations of apprehension, can only be
represented as the object of the same, distinct therefrom, if it
stands under a rule, which distinguishes _it_ from every _other_
representation and which renders necessary a mode of conjunction of
the manifold."[32]
[30] The italics are mine.
[31] This is implied both by the use of 'also' and by the
context.
[32] The italics are mine.
Since Kant in introducing his vindication of causality thus identifies
elements in the object apprehended (i. e. the manifold of phenomena)
with the apprehensions of them, we approach the vindication itself
with the expectation that he will identify a causal rule, which
consists in a necessity in the succession of objects, viz. of events
in nature, with the necessity in the succession of our apprehensions
of them. This expectation turns out justified. The following passage
adequately expresses the vindication:
"Let us now proceed to our task. That something happens, i. e. that
something or some state comes to be which before was not, cannot be
empirically perceived, unless a phenomenon precedes, which does not
contain in itself this state; for a reality which follows upon an
empty time, and therefore a coming into existence preceded by no state
of things, can just as little be apprehended as empty time itself.
Every apprehension of an event is therefore a perception which follows
upon another perception. But because this is the case with all
synthesis of apprehension, as I have shown above[33] in the phenomenon
of a house, the apprehension of an event is thereby not yet
distinguished from other apprehensions. But I notice also, that if in
a phenomenon which contains an event, I call the preceding state of my
perception A, and the following state B, B can only follow A in
apprehension, while the perception A cannot follow B but can only
precede it. For example, I see a ship float down a stream. My
perception of its place lower down follows upon my perception of its
place higher up the course of the river, and it is impossible that in
the apprehension of this phenomenon the vessel should be perceived
first below and afterwards higher up the stream. Here, therefore, the
order in the sequence of perceptions in apprehension is determined,
and apprehension is bound to this order. In the former example of a
house, my perceptions in apprehension could begin at the roof and end
at the foundation, or begin below and end above; in the same way they
could apprehend the manifold of the empirical perception from left to
right, or from right to left. Accordingly, in the series of these
perceptions, there was no determined order, which necessitated my
beginning at a certain point, in order to combine the manifold
empirically. But this rule is always to be found in the perception of
that which happens, and it makes the order of the successive
perceptions (in the apprehension of this phenomenon) _necessary_."
[33] B. 235-6, M. 143 (quoted p. 279).
"In the present case, therefore, I shall have to derive the
_subjective sequence_ of apprehension from the _objective sequence_ of
phenomena, for otherwise the former is wholly undetermined, and does
not distinguish one phenomenon from another. The former alone proves
nothing as to the connexion of the manifold in the object, for it is
wholly arbitrary. The latter, therefore [i. e. the objective sequence
of phenomena[34]], will consist in that order of the manifold of the
phenomenon, according to which the apprehension of the one (that which
happens) follows that of the other (that which precedes) _according to
a rule_. In this way alone can I be justified in saying of the
phenomenon itself, and not merely of my apprehension, that a sequence
is to be found therein, which is the same as to say that I cannot
arrange my apprehension otherwise than in just this sequence."
[34] The sense is not affected if 'the latter' be understood
to refer to the connexion of the manifold in the object.
"In conformity with such a rule, therefore, there must exist in that
which in general precedes an event the condition of a rule, according
to which this event follows always and necessarily, but I cannot
conversely go back from the event, and determine (by apprehension)
that which precedes it. For no phenomenon goes back from the
succeeding point of time to the preceding point, although it does
certainly relate to _some preceding point of time_; on the other hand,
the advance from a given time to the determinate succeeding time is
necessary. Therefore, because there certainly is something which
follows, I must relate it necessarily to something else in general,
which precedes, and upon which it follows in conformity with a rule,
that is necessarily, so that the event, as the conditioned, affords
certain indication of some condition, while this condition determines
the event."
"If we suppose that nothing precedes an event, upon which this event
must follow in conformity with a rule, all sequence of perception
would exist only in apprehension, i. e. would be merely subjective,
but it would not thereby be objectively determined which of the
perceptions must in fact be the preceding and which the succeeding
one. We should in this manner have only a play of representations,
which would not be related to any object, i. e. no phenomenon would be
distinguished through our perception in respect of time relations from
any other, because the succession in apprehension is always of the
same kind, and so there is nothing in the phenomenon to determine the
succession, so as to render a certain sequence objectively necessary.
I could therefore not say that in the phenomenon two states follow
each other, but only that one apprehension follows on another, a fact
which is merely _subjective_ and does not determine any object, and
cannot therefore be considered as knowledge of an object (not even in
the phenomenon)."
"If therefore we experience that something happens, we always thereby
presuppose that something precedes, on which it follows according to a
rule. For otherwise, I should not say of the object, that it follows,
because the mere sequence in my apprehension, if it is not determined
by a rule in relation to something preceding, does not justify the
assumption of a sequence in the object. It is therefore always in
reference to a rule, according to which phenomena are determined in
their sequence (i. e. as they happen) by the preceding state, that I
make my subjective synthesis (of apprehension) objective, and it is
solely upon this presupposition that even the experience of something
which happens is possible."[35]
[35] B. 236-41, M. 144-6.
The meaning of the first paragraph is plain. Kant is saying that when
we reflect upon the process by which we come to apprehend the world of
nature, we can lay down two propositions. The first is that the
process is equally successive whether the object apprehended be a
succession in nature or a coexistence of bodies in space, so that the
knowledge that we have a succession of apprehensions would not by
itself enable us to decide whether the object of the apprehensions is
a sequence or not. The second proposition is that, nevertheless, there
is this difference between the succession of our apprehensions where
we apprehend a succession and where we apprehend a coexistence, that
in the former case, and in that only, the succession of our
apprehensions is irreversible or, in other words, is the expression of
a rule of order which makes it a necessary succession. So far we find
no mention of causality, i. e. of a necessity of succession in
objects, but only a necessity of succession in our apprehension of
them. So far, again, we find no contribution to the problem of
explaining how we distinguish between successive perceptions which are
the perceptions of an event and those which are not. For it is
reasonable to object that it is only possible to say that the order of
our perceptions is irreversible, if and because we already know that
what we have been perceiving is an event, and that therefore any
attempt to argue from the irreversibility of our perceptions to the
existence of a sequence in the object must involve a [Greek: hysteron
proteron]. And it is clear that, if irreversibility in our perceptions
were the only irreversibility to which appeal could be made, even Kant
would not have supposed that the apprehension of a succession was
reached through belief in an irreversibility.
The next paragraph, of which the interpretation is difficult, appears
to introduce a causal rule, i. e. an irreversibility in objects, by
identifying it with the irreversibility in our perceptions of which
Kant has been speaking. The first step to this identification is taken
by the assertion: "In the present case, therefore, I shall have to
derive the subjective sequence of perceptions from the objective
sequence of phenomena.... The latter will consist in the order of the
_manifold of the phenomenon_, according to which _the apprehension_ of
the one (that which happens) follows that of the other (that which
precedes) according to a rule."[36] Here Kant definitely implies that
an objective sequence, i. e. an order or sequence of the _manifold_ of
a phenomenon, consists in a sequence of _perceptions or apprehensions_
of which the order is necessary or according to a rule; in other
words, that a succession of perceptions in the special case where the
succession is necessary is a succession of events perceived.[37] This
implication enables us to understand the meaning of the assertion that
'we must therefore derive the subjective sequence of perceptions from
the objective sequence of phenomena', and to see its connexion with
the preceding paragraph. It means, 'in view of the fact that in all
apprehensions of a succession, and in them alone, the sequence of
perceptions is irreversible, we are justified in saying that a given
sequence of perceptions is the apprehension of a succession, if we
know that the sequence is irreversible; in that case we must be
apprehending a real succession, for an irreversible sequence of
perceptions _is_ a sequence of events perceived.' Having thus implied
that irreversibility of perceptions constitutes them events perceived,
he is naturally enough able to go on to speak of the irreversibility
of perceptions as if it were the same thing as an irreversibility of
events perceived, and thus to bring in a causal rule. "In this way
alone [i. e. only by deriving the subjective from the objective
sequence] can I be justified in saying of the phenomenon itself, and
not merely of my apprehension, that a sequence is to be found therein,
_which is the same as to say_ that I cannot _arrange_ my apprehension
otherwise than in just this sequence. In conformity with _such a
rule_, therefore, there must exist in that which in general precedes
_an event_ the condition of a rule, according to which _this event
follows always and necessarily_."[38] Here the use of the word
'arrange'[39] and the statement about the rule in the next sentence
imply that Kant has now come to think of the rule of succession as a
causal rule relating to the objective succession. Moreover, if any
doubt remains as to whether Kant really confuses the two
irreversibilities or necessities of succession, it is removed by the
last paragraph of the passage quoted. "If therefore we experience that
something happens, we always thereby presuppose that something
precedes on which _it_ follows according to a rule. For otherwise I
should not say of the object that _it_ follows; because the mere
succession of my apprehension, if _it_ is not determined by a rule in
relation to something preceding, does not justify the assumption of a
succession in the object. It is therefore always in reference to a
rule, according to which _phenomena_ are determined in their sequence
(i. e. as they happen) by the preceding state, that I make my
subjective sequence (of apprehension) objective."[40] The fact is
simply that Kant _must_ identify the two irreversibilities, because,
as has been pointed out, he has only one set of terms to be related as
irreversible, viz. the elements of the manifold, which have to be,
from one point of view, elements of an object and, from another,
representations or apprehensions of it.
[36] The italics are mine. 'According to which' does not
appear to indicate that the two orders referred to are
different.
[37] Cf. B. 242 fin., M. 147 fin.
[38] The italics are mine
[39] _Anstellen._
[40] The italics are mine.
As soon, therefore, as the real nature of Kant's vindication of
causality has been laid bare, it is difficult to describe it as an
argument at all. He is anxious to show that in apprehending A B as a
real or objective succession we presuppose that they are elements in a
causal order of succession. Yet in support of his contention he points
only to the quite different fact that where we apprehend a succession
A B, we think of the _perception_ of A and the _perception_ of B as
elements in a necessary but subjective succession.
Before we attempt to consider the facts with which Kant is dealing, we
must refer to a feature in Kant's account to which no allusion has
been made. We should on the whole expect from the passage quoted that,
in the case where we regard two perceptions A B as necessarily
successive and therefore as constituting an objective succession, the
necessity of succession consists in the fact that A is the cause of B.
This, however, is apparently not Kant's view; on the contrary, he
seems to hold that, in thinking of A B as an objective succession, we
presuppose not that A causes B, but only that the state of affairs
which precedes B, and which therefore includes A, contains a cause of
B, the coexistence or identity of this cause with A rendering the
particular succession A B necessary. "Thus [if I perceive that
something happens] it arises that there comes to be an order among our
representations in which the present (so far as it has taken place)
points to some preceding state as a correlate, _though a still
undetermined correlate_,[41] of this event which is given, and this
correlate relates to the event by determining the event as its
consequence, and connects the event with itself necessarily in the
series of time."[42]
[41] The italics are mine.
[42] B. 244, M. 148. Cf. B. 243, M. 148 (first half) and B.
239, M. 145 (second paragraph). The same implication is to
be found in his formulation of the rule involved in the
perception of an event, e. g. "In conformity with such a
rule, there must exist in that which in general precedes an
event, the condition of a rule, according to which this event
follows always and necessarily." Here the condition of a rule
is the necessary antecedent of the event, whatever it may be.
The fact is that Kant is in a difficulty which he feels obscurely
himself. He seems driven to this view for two reasons. If he were to
maintain that A was necessarily the cause of B, he would be
maintaining that all observed sequences are causal, i. e. that in them
the antecedent and consequent are always cause and effect, which is
palpably contrary to fact. Again, his aim is to show that we become
aware of a succession by presupposing the law of causality. This law,
however, is quite general, and only asserts that _something_ must
precede an event upon which it follows always and necessarily. Hence
by itself it palpably gives no means of determining whether this
something is A rather than anything else.[43] Therefore if he were
to maintain that the antecedent member of an apprehended objective
succession must be thought of as its cause, the analogy would
obviously provide no means of determining the antecedent member, and
therefore the succession itself, for the succession must be the
sequence of B upon some definite antecedent. On the other hand, the
view that the cause of B need not be A only incurs the same difficulty
in a rather less obvious form. For, even on this view, the argument
implies that in order to apprehend two individual perceptions A B as
an objective succession, we must know that A _must_ precede B, and the
presupposition that B implies a cause in the state of affairs
preceding B in no way enables us to say either that A coexists with
the cause, or that it is identical with it, and therefore that it must
precede B.
[43] Cf. B. 165, M. 101, where Kant points out that the
determination of particular laws of nature requires
experience.
Nevertheless, it cannot be regarded as certain that Kant did not think
of A, the apprehended antecedent of B, as necessarily the cause of B,
for his language is both ambiguous and inconsistent. When he considers
the apprehension of a succession from the side of the successive
perceptions, he at least tends to think of A B as cause and
effect;[44] and it may well be that in discussing the problem from
the side of the law of causality, he means the cause of B to be A,
although the generality of the law compels him to refer to it as
_something_ upon which B follows according to a rule.
[44] He definitely implies this, B. 234, M. 142.
Further, it should be noticed that to allow as Kant, in effect, does
elsewhere[45], that experience is needed to determine the cause of B is
really to concede that the apprehension of objective successions is
_prior to_, and _presupposed by_, any process which appeals to the
principle of causality; for if the principle of causality does not by
itself enable us to determine the cause of B, it cannot do more than
enable us to pick out the cause of B among events known to precede B
independently of the principle. Hence, from this point of view, there
can be no process such as Kant is trying to describe, and therefore
its precise nature is a matter of indifference.
[45] Cf. B. 165, M. 101, where Kant points out that the
determination of particular laws of nature requires
experience.
We may now turn to the facts. There is, it seems, no such thing as a
process by which, beginning with the knowledge of successive
apprehensions or representations, of the object of which we are
unaware, we come to be aware of their object. Still less is there a
process--and it is really this which Kant is trying to describe--by
which, so beginning, we come to apprehend these successive
representations as objects, i. e. as parts of the physical world,
through the thought of them as necessarily related. We may take Kant's
instance of our apprehension of a boat going down stream. We do not
first apprehend two perceptions of which the object is undetermined
and then decide that their object is a succession rather than a
coexistence. Still less do we first apprehend two perceptions or
representations and then decide that they are related as successive
events in the physical world. From the beginning we apprehend a real
sequence, viz. the fact that the boat having left one place is
arriving at another; there is no process _to_ this apprehension. In
other words, from the beginning we are aware of real elements, viz. of
events in nature, and we are aware of them as really related, viz. as
successive in nature. This must be so. For if we begin with the
awareness of two mere perceptions, we could never thence reach the
knowledge that their object was a succession, or even the knowledge
that they had an object; nor, so beginning, could we become aware of
the perceptions themselves as successive events in the physical world.
For suppose, _per impossibile_, the existence of a process by which we
come to be aware of two elements A and B as standing in a relation of
sequence in the physical world. In the first place, A and B, with the
awareness of which we begin, must be, and be known to be, real or
objective, and not perceptions or apprehensions; otherwise we could
never come to apprehend them as related in the physical world. In the
second place, A and B must be, and be known to be, real with the
reality of a physical event, otherwise we could never come to
apprehend them as related by way of succession in the physical world.
If A and B were bodies, as they are when we apprehend the parts of a
house, they could never be apprehended as successive. In other words,
the process by which, on Kant's view, A and B become, and become known
to be, events presupposes that they already are, and are known to be,
events. Again, even if it be granted that A and B are real events, it
is clear that there can be no process by which we come to apprehend
them as successive. For if we apprehended events A and B separately,
we could never thence advance to the apprehension of their relation,
or, in other words, we could never discover which came first. Kant
himself saw clearly that the perception of A followed by the
perception of B does not by itself yield the perception that B follows
A. In fact it was this insight which formed the starting-point of his
discussion.[46] Unfortunately, instead of concluding that the
apprehension of a succession is ultimate and underivable from a more
primitive apprehension, he tried to formulate the nature of the
process by which, starting from such a succession of perceptions, we
reach the apprehension of a succession. The truth is simply that there
is and can be no _process to_ the apprehension of a succession; in
other words, that we do and must apprehend a real succession
immediately or not at all. The same considerations can of course be
supplied _mutatis mutandis_ to the apprehension of the coexistence of
bodies in space, e. g. of the parts of a house.
[46] Cf. B. 237, M. 144.
It may be objected that this denial of the existence of the process
which Kant is trying to describe must at least be an overstatement.
For the assertion that the apprehension of a succession or of a
coexistence is immediate may seem to imply that the apprehension of
the course of a boat or of the shape of a house involves no process at
all; yet either apprehension clearly takes time and so must involve a
process. But though a process is obviously involved, it is not a
process from the apprehension of what is not a succession to the
apprehension of a succession, but a process from the apprehension of
one succession to that of another. It is the process by which we pass
from the apprehension of one part of a succession which may have, and
which it is known may have, other parts to the apprehension of what
is, and what is known to be, another part of the same succession.
Moreover, the assertion that the apprehension of a succession must be
immediate does not imply that it may not be reached by a process. It
is not inconsistent with the obvious fact that to apprehend that the
boat is now turning a corner is really to apprehend that what before
was going straight is now changing its course, and therefore
presupposes a previous apprehension of the boat's course as straight.
It only implies that the apprehension of a succession, if reached by a
process at all, is not reached by a process of which the
starting-point is not itself the apprehension of a succession.
Nevertheless, a plausible defence of Kant's treatment of causality can
be found, which may be formulated thus: 'Time, just as much as space,
is a sphere within which we have to distinguish between appearance and
reality. For instance, when moving in a lift, we see, as we say, the
walls moving, while the lift remains stationary. When sitting in a
train which is beginning to move out of a station, we see, as we say,
another train beginning to move, although it is in fact standing
still. When looking at distant trees from a fast train, we see, as we
say, the buildings in the intermediate space moving backwards. In
these cases the events seen are not real, and we only succeed in
determining what is really happening, by a process which presupposes
the law of causality. Thus, in the last case we only believe that the
intermediate buildings do not move, by realizing that, given the
uniformity of nature, belief in their motion is incompatible with what
we believe on the strength of experience of these buildings on other
occasions and of the rest of the world. These cases prove the
existence of a process which enables us, and is required to enable us,
to decide whether a given change is objective or subjective, i. e.
whether it lies in the reality apprehended or in our apprehension of
it; and this process involves an appeal to causality. Kant's mistake
lay in his choice of illustrations. His illustrations implied that the
process which involves causality is one by which we distinguish a
succession in the object apprehended from another relation in the
object, viz. a coexistence of bodies. But he ought to have taken
illustrations which implied that the process is one by which we
distinguish a succession in the object from a succession in our
perception of it. In other words, the illustrations should, like those
just given, have illustrated the process by which we distinguish an
objective from a subjective change, and not a process by which we
distinguish an objective change from something else also objective.
Consequently, Kant's conclusion and his _general_ method of treatment
are right, even if, misled by his instances, he supports his position
by arguments which are wrong.'
This defence is, however, open to the following reply: 'At first sight
the cases taken undoubtedly seem to illustrate a process in which we
seek to discover whether a certain change belongs to objects or only
to our apprehension of them, and in which we appeal to causality in
arriving at a decision. But this is only because we ignore the
relativity of motion. To take the third case: our first statement of
the facts is that we saw the intermediate buildings moving, but that
subsequent reflection on the results of other experience forced us to
conclude that the change perceived was after all only in our
apprehension and not in the things apprehended. The statement,
however, that we saw the buildings moving really assumes that we, the
observers, were stationary; and it states too much. What we really
perceived was a relative changing of position between us, the near
buildings, and the distant trees. This is a fact, and the apprehension
of it, therefore, does not afterwards prove mistaken. It is equally
compatible with motion on the part of the trees, or of the buildings,
or of the observers, or of a combination of them; and that for which
an appeal to causality is needed is the problem of deciding which of
these alternatives is correct. Moreover, the perceived relative change
of position is objective; it concerns the things apprehended. Hence,
in this case too, it can be said that we perceive an objective
succession from the beginning, and that the appeal to causality is
only needed to determine something further about it. It is useless to
urge that to be aware of an event is to be aware of it in all its
definiteness, and that this awareness admittedly involves an appeal to
causality; for it is easy to see that unless our awareness of the
relative motion formed the starting-point of any subsequent process in
which we appealed to the law of causality, we could never use the law
to determine which body really moved.'
Two remarks may be made in conclusion. In the first place, the basis
of Kant's account, viz. the view that in our apprehension of the world
we advance from the apprehension of a succession of perceptions to
the apprehension of objects perceived, involves a [Greek: hysteron
proteron]. As Kant himself in effect urges in the _Refutation of
Idealism_,[47] self-consciousness, in the sense of the consciousness
of the successive process in which we apprehend the world, is plainly
only attained by reflecting upon our apprehension of the world. We
first apprehend the world and only by subsequent reflection become
aware of our activity in apprehending it. Even if consciousness of
the world must lead to, and so is in a sense inseparable from,
self-consciousness, it is none the less its presupposition.
[47] Cf. p. 320.
In the second place, it seems that the true vindication of causality,
like that of the first analogy, lies in the dogmatic method which Kant
rejects. It consists in insight into the fact that it is of the very
nature of a physical event to be an element in a process of change
undergone by a system of substances in space, this process being
through and through necessary in the sense that any event (i. e. the
attainment of any state by a substance) is the outcome of certain
preceding events (i. e. the previous attainment of certain states by
it and other substances), and is similarly the condition of certain
subsequent events.[48] To attain this insight, we have only to reflect
upon what we really mean by a 'physical event'. The vindication can
also be expressed in the form that the very _thought_ of a physical
event presupposes the _thought_ of it as an element in a necessary
process of change--provided, however, that no distinction is implied
between the nature of a thing and what we think its nature to be. But
to vindicate causality in this way is to pursue the dogmatic method;
it is to argue from the nature, or, to use Kant's phrase, from the
conception, of a physical event. On the other hand, it seems that the
method of arguing transcendentally, or from the possibility of
perceiving events, must be doomed to failure in principle. For if, as
has been argued to be the case,[49] apprehension is essentially the
apprehension of a reality as it exists independently of the
apprehension of it, only those characteristics can be attributed to
it, as characteristics which it must have if it is to be apprehended,
which belong to it in its own nature or in virtue of its being what it
is. It can only be because we think that a thing has some
characteristic in virtue of its own nature, and so think
'dogmatically', that we can think that in apprehending it we must
apprehend it as having that characteristic.[50]
[48] This statement of course includes the third analogy.
[49] Cf. Chh. IV and VI.
[50] Cf. p. 275.
There remains to be considered Kant's proof of the third analogy,
i. e. the principle that all substances, so far as they can be
perceived in space as coexistent, are in thorough-going interaction.
The account is extremely confused, and it is difficult to extract from
it a consistent view. We shall consider here the version added in the
second edition, as being the fuller and the less unintelligible.
"Things are _coexistent_, when in empirical intuition[51] the
perception[52] of the one can follow upon the perception of the other,
and vice versa (which cannot occur in the temporal succession of
phenomena, as we have shown in the second principle). Thus I can
direct my perception first to the moon and afterwards to the earth, or
conversely, first to the earth and then to the moon, and because the
perceptions of these objects can reciprocally follow each other, I say
that they coexist. Now coexistence is the existence of the manifold in
the same time. But we cannot perceive time itself, so as to conclude
from the fact that things are placed in the same time that the
perceptions of them can follow each other reciprocally. The synthesis
of the imagination in apprehension, therefore, would only give us each
of these perceptions as existing in the subject when the other is
absent and vice versa; but it would not give us that the objects are
coexistent, i. e. that, if the one exists, the other also exists in
the same time, and that this is necessary in order that the
perceptions can follow each other reciprocally. Hence there is needed
a conception-of-the-understanding[53] of the reciprocal sequence of
the determinations of these things coexisting externally to one
another, in order to say that the reciprocal succession of perceptions
is grounded in the object, and thereby to represent the coexistence as
objective. But the relation of substances in which the one contains
determinations the ground of which is contained in the other is the
relation of influence, and if, reciprocally, the former contains the
ground of the determinations in the latter, it is the relation of
community or interaction. Consequently, the coexistence of substances
in space cannot be known in experience otherwise than under the
presupposition of their interaction; this is therefore also the
condition of the possibility of things themselves as objects of
experience."[54]
[51] _Anschauung._
[52] _Wahrnehmung._
[53] _Verstandesbegriff._
[54] B. 257-8, M. 156-7.
The proof begins, as we should expect, in a way parallel to that of
causality. Just as Kant had apparently argued that we learn that a
succession of perceptions is the perception of a sequence when we find
the order of the perceptions to be irreversible, so he now definitely
asserts that we learn that certain perceptions are the perceptions of
a coexistence of bodies in space when we find that the order of the
perceptions is reversible, or, to use Kant's language, that there can
be a reciprocal sequence of the perceptions. This beginning, if read
by itself, seems as though it should also be the end. There seems
nothing more which need be said. Just as we should have expected Kant
to have completed his account of the apprehension of a succession when
he pointed out that it is distinguished by the irreversibility of the
perceptions, so here we should expect him to have said enough when he
points out that the earth and the moon are said to be coexistent
because our perceptions of them can follow one another reciprocally.
The analogy, however, has in some way to be brought in, and to this
the rest of the proof is devoted. In order to consider how this is
done, we must first consider the nature of the analogy itself. Kant
speaks of 'a conception-of-the-understanding of the reciprocal
sequence of the determinations of things which coexist externally to
one another'; and he says that 'that relation of substances in which
the one contains determinations, the ground of which is contained in
the other substance, is the relation of influence'. His meaning can be
illustrated thus. Suppose two bodies, A, a lump of ice, and B, a fire,
close together, yet at such a distance that they can be observed in
succession. Suppose that A passes through changes of temperature a_{1}
a_{2} a_{3} ... in certain times, the changes ending in states
[alpha]_{1} [alpha]_{2} [alpha]_{3} ..., and that B passes through
changes of temperature b_{1} b_{2} b_{3} ... in the same times, the
changes ending in states [beta]_{1} [beta]_{2} [beta]_{3}. Suppose
also, as we must, that A and B interact, i. e. that A in passing
through its changes conditions the changes through which B passes, and
therefore also the states in which B ends, and vice versa, so that
a_{2} and [alpha]_{2} will be the outcome not of a_{1} and [alpha]_{1}
alone, but of a_{1} and [alpha]_{1}, and b_{1} and [beta]_{1} jointly.
Then we can say (1) that A and B are in the relation of influence, and
also of interaction or reciprocal influence, in the sense that they
_mutually_ (not alternately) determine one another's states. Again, if
we first perceive A in the state [alpha]_1 by a perception A_{1}, then
B in the state [beta]_{2} by a perception B_{2}, then A in the state
[alpha]_{3} by a perception A_{3} and so on, we can speak (2) of a
reciprocal sequence of perceptions, in the sense of a sequence of
perceptions in which alternately a perception of B follows a
perception of A and a perception of A follows a perception of B; for
first a perception of B, viz. B_{2}, follows a perception of A, viz.
A_{1}, and then a perception of A, viz. A_{3}, follows a perception of
B, viz. B_{2}. We can also speak (3) of a reciprocal sequence of the
determinations of two things in the sense of a necessary succession of
states which _alternately_ are states of A and of B; for [alpha]_{1},
which is perceived first, can be said to contribute to determine
[beta]_{2}, which is perceived next, and [beta]_{2} can be said to
contribute to determine [alpha]_{3}, which is perceived next, and so
on; and this reciprocal sequence can be said to be involved in the
very nature of interaction. Further, it can be said (4) that if we
perceive A and B alternately, and so only in the states [alpha]_{1}
[alpha]_{3} ... [beta]_{2} [beta]_{4} ... respectively, we can
only fill in the blanks, i. e. discover the states [alpha]_{2}
[alpha]_{4} ... [beta]_{1} [beta]_{3} ... _coexistent_ with [beta]_{2}
[beta]_{4} ... and [alpha]_{1} [alpha]_{3} ... respectively, if we
presuppose the thought of interaction. For it is only possible to use
the observed states as a clue to the unobserved states, if we
presuppose that the observed states are members of a necessary
succession of which the unobserved states are also members and
therefore have partially determined and been determined by the
observed states. Hence it may be said that the determination of the
unobserved states coexistent with the observed states presupposes the
thought of interaction.
How then does Kant advance from the assertion that the apprehension of
a coexistence requires the knowledge that our _perceptions_ can be
reciprocally sequent to the assertion that it presupposes the thought
that the _determinations of phenomena_ are reciprocally sequent? The
passage in which the transition is effected is obscure and confused,
but it is capable of interpretation as soon as we see that it is
intended to run parallel to the proof of the second analogy which is
added in the second edition.[55] Kant apparently puts to himself the
question, 'How are we to know when we have a reciprocal sequence of
perceptions from which we can infer a coexistence in what we
perceived?' and apparently answers it thus: 'Since we cannot perceive
time, and therefore cannot perceive objects as dated in time with
respect to one another, we cannot begin with the apprehension of the
coexistence of two objects, and thence infer the possibility of
reciprocal sequence in our perceptions. This being so, the synthesis
of imagination in apprehension can indeed combine these perceptions
[these now being really considered as determinations or states of an
object perceived] in a reciprocal sequence, but there is so far no
guarantee that the sequence produced by the synthesis is not an
arbitrary product of the imagination, and therefore we cannot think of
it as a reciprocal sequence in objects. In order to think of such a
reciprocal sequence as not arbitrary but as constituting a real
sequence in objects [ = 'as grounded in the object'], we must think of
the states reciprocally sequent [as necessarily related and therefore]
as successive states of two coexisting substances which interact or
mutually determine one another's successive states. Only then shall we
be able to think of the coexistence of objects involved in the
reciprocal sequence as an objective fact, and not merely as an
arbitrary product of the imagination.' But, if this fairly expresses
Kant's meaning, his argument is clearly vitiated by two confusions. In
the first place, it confuses a subjective sequence of perceptions
which are alternately perceptions of A and of B, two bodies in space,
with an objective sequence of perceived states of bodies, [alpha]_{1}
[beta]_{2} [alpha]_{3} [beta]_{4}, which are alternately states of two
bodies A and B, the same thing being regarded at once as a perception
and as a state of a physical object. In the second place, mainly in
consequence of the first confusion, it confuses the necessity that the
perceptions of A and of B can follow one another alternately with the
necessity of succession in the alternately perceived states of A and B
as interacting. Moreover, there is really a change in the cases under
consideration. The case with which he begins, i. e. when he is
considering merely the reciprocal sequence of perceptions, is the
successive perceptions of two _bodies in space_ alternately, e. g. of
the moon and the earth, the nature of their states at the time of
perception not being in question. But the case with which he ends is
the successive perception of the _states of two bodies_ alternately,
e. g. of the states of the fire and of the lump of ice. Moreover, it
is only in the latter case that the objective relation apprehended is
that of coexistence in the proper sense, and in the sense which Kant
intends throughout, viz. that of being contemporaneous in distinction
from being successive. For when we say that two bodies, e. g. the moon
and the earth, coexist, we should only mean that both exist, and not,
as Kant means, that they are contemporaneous. For to a substance,
being as it is the substratum of changes, we can ascribe no temporal
predicates. That which changes cannot be said either to begin, or to
end, or to exist at a certain moment of time, or, therefore, to exist
contemporaneously with, or after, or before anything else; it cannot
even be said to persist through a portion of time or, to use the
phrase of the first analogy, to be permanent. It will be objected
that, though the cases are different, yet the transition from the one
to the other is justified, for it is precisely Kant's point that the
existence together of two substances in space can only be discovered
by consideration of their successive states under the presupposition
that they mutually determine one another's states. "Besides the mere
fact of existence there must be something by which A determines the
place in time for B, and conversely B the place for A, because only
under this condition can these substances be empirically represented
as coexistent."[56] The objection, however, should be met by two
considerations, each of which is of some intrinsic importance. In the
first place, the apprehension of a body in space in itself involves
the apprehension that it exists together with all other bodies in
space, for the apprehension of something as spatial involves the
apprehension of it as spatially related to, and therefore as existing
together with, everything else which is spatial. No process,
therefore, such as Kant describes is required in order that we may
learn that it exists along with some other body. In the second place,
that for which the principle of interaction is really required is not,
as Kant supposes, the determination of the coexistence of an
unperceived body with a perceived body, but the determination of that
unperceived state of a body already known to exist which is coexistent
with a perceived state of a perceived body. As has been pointed out,
if we perceive A and B alternately in the states [alpha]_{1}
[beta]_{2} [alpha]_{3} [beta]_{4} ... we need the thought of
interaction to determine the nature of [beta]_{1} [alpha]_{2}
[beta]_{3} [alpha]_{4} ... Thus it appears that Kant in his
vindication of the third analogy omits altogether to notice the one
process which really presupposes it.
[55] B. 233-4, M. 142.
[56] B. 259, M. 157.