Kant's Theory of Knowledge Part 2

An inherent difficulty, however, of this 'physical' theory of perception leads to a transformation of it. If, as the theory supposes, the cause of sensation is outside or beyond the mind, it cannot be known. Hence the initial a.s.sumption that this cause is the physical world has to be withdrawn, and the cause of sensation comes to be thought of as the thing in itself of which we can know nothing.

This is undoubtedly the normal form of the theory in Kant's mind.

It may be objected that to attribute to Kant at any time the physical form of the theory is to accuse him of an impossibly crude confusion between things in themselves and the spatial world, and that he can never have thought that the cause of sensation, being as it is outside the mind, is spatial. But the answer is to be found in the fact that the problem just referred to as occupying Kant's attention in the _Aesthetic_ is only a problem at all so long as the cause of sensation is thought of as a physical body. For the problem 'How do we, beginning with mere sensation, come to know a spatial and temporal world?' is only a problem so long as it is supposed that the cause of sensation is a spatial and temporal world or a part of it, and that this world is what we come to know. If the cause of sensation, as being beyond the mind, is held to be unknowable and so not known to be spatial or temporal, the problem has disappeared. Corroboration is given by certain pa.s.sages[11] in the _Critique_ which definitely mention 'the senses', a term which refers to bodily organs, and by others[12] to which meaning can be given only if they are taken to imply that the objects which affect our sensibility are not unknown things in themselves, but things known to be spatial. Even the use of the plural in the term 'things in themselves' implies a tendency to identify the unknowable reality beyond the mind with bodies in s.p.a.ce.

For the implication that different sensations are due to different things in themselves originates in the view that different sensations are due to the operation of different spatial bodies.

[11] E. g. B. 1 init., M. 1 init., and B. 75 fin., M. 46, lines 12, 13 [for 'the sensuous faculty' should be subst.i.tuted 'the senses'].

[12] E. g. B. 42, lines 11, 12; M. 26, line 13; A. 100, Mah.

195 ('even in the absence of the object'). Cf. B. 182-3, M.

110-1 (see pp. 257-8, and note p. 257), and B. 207-10, M.

126-8 (see pp. 263-5).

It is now necessary to consider how the distinction between the sensibility and the understanding contributes to articulate the problem 'How are _a priori_ synthetic judgements possible?' As has been pointed out, Kant means by this question, 'How is it possible that the mind is able, in virtue of its own powers, to make universal and necessary judgements which antic.i.p.ate its experience of objects?'

To this question his general answer is that it is possible and only possible because, so far from ideas, as is generally supposed, having to conform to things, the things to which our ideas or judgements relate, viz. phenomena, must conform to the nature of the mind. Now, if the mind's knowing nature can be divided into the sensibility and the understanding, the problem becomes 'How is it possible for the mind to make such judgements in virtue of its sensibility and its understanding?' And the answer will be that it is possible because the things concerned, i. e. phenomena, must conform to the sensibility and the understanding, i. e. to the mind's perceiving and thinking nature.

But both the problem and the answer, so stated, give no clue to the particular _a priori_ judgements thus rendered possible nor to the nature of the sensibility and the understanding in virtue of which we make them. It has been seen, however, that the judgements in question fall into two cla.s.ses, those of mathematics and those which form the presuppositions of physics. And it is Kant's aim to relate these cla.s.ses to the sensibility and the understanding respectively. His view is that mathematical judgements, which, as such, deal with spatial and temporal relations, are essentially bound up with our perceptive nature, i. e. with our sensibility, and that the principles underlying physics are the expression of our thinking nature, i. e. of our understanding. Hence if the vindication of this relation between our knowing faculties and the judgements to which they are held to give rise is approached from the side of our faculties, it must be shown that our sensitive nature is such as to give rise to mathematical judgements, and that our understanding or thinking nature is such as to originate the principles underlying physics. Again, if the account of this relation is to be adequate, it must be shown to be exhaustive, i. e. it must be shown that the sensibility and the understanding give rise to no other judgements. Otherwise there may be other _a priori_ judgements bound up with the sensibility and the understanding which the inquiry will have ignored. Kant, therefore, by his distinction between the sensibility and the understanding, sets himself another problem, which does not come into sight in the first formulation of the general question 'How are _a priori_ synthetic judgements possible?' He has to determine what _a priori_ judgements are related to the sensibility and to the understanding respectively.

At the same time the distinction gives rise to a division within the main problem. His chief aim is to discover how it is that _a priori_ judgements are universally applicable. But, as Kant conceives the issue, the problem requires different treatment according as the judgements in question are related to the sensibility or to the understanding. Hence arises the distinction between the _Transcendental Aesthetic_ and the _Transcendental a.n.a.lytic_, the former dealing with the _a priori_ judgements of mathematics, which relate to the sensibility, and the latter dealing with the _a priori_ principles of physics, which originate in the understanding. Again, within each of these two divisions we have to distinguish two problems, viz. 'What _a priori_ judgements are essentially related to the faculty in question?' and 'How is it that they are applicable to objects?'

It is important, however, to notice that the distinction between the sensibility and the understanding, in the form in which it serves as a basis for distinguishing the _Aesthetic_ and the _a.n.a.lytic_, is not identical with or even compatible with the distinction, as Kant states it when he is considering the distinction in itself and is not thinking of any theory which is to be based upon it. In the latter case the sensibility and the understanding are represented as inseparable faculties involved in _all_ knowledge.[13] Only from the union of both can knowledge arise. But, regarded as a basis for the distinction between the _Aesthetic_ and the _a.n.a.lytic_, they are implied to be the source of different kinds of knowledge, viz.

mathematics and the principles of physics. It is no answer to this to urge that Kant afterwards points out that s.p.a.ce as an object presupposes a synthesis which does not belong to sense. No doubt this admission implies that even the apprehension of spatial relations involves the activity of the understanding. But the implication is really inconsistent with the existence of the _Aesthetic_ as a distinct part of the subject dealing with a special cla.s.s of _a priori_ judgements.

[13] B. 74-5, M. 45-6; cf. pp. 27-9.

[14] B. 160 note, M. 98 note.

CHAPTER III

s.p.a.cE

It is the aim of the _Aesthetic_ to deal with the _a priori_ knowledge which relates to the sensibility. This knowledge, according to Kant, is concerned with s.p.a.ce and time. Hence he has to show _firstly_ that our apprehension of s.p.a.ce and time is _a priori_, i. e. that it is not derived from experience but originates in our apprehending nature; and _secondly_ that within our apprehending nature this apprehension belongs to the sensibility and not to the understanding, or, in his language, that s.p.a.ce and time are forms of perception or sensibility.

Further, if his treatment is to be exhaustive, he should also show _thirdly_ that s.p.a.ce and time are the only forms of perception. This, however, he makes no attempt to do except in one pa.s.sage,[1] where the argument fails. The first two points established, Kant is able to develop his main thesis, viz. that it is a condition of the validity of the _a priori_ judgements which relate to s.p.a.ce and time that these are characteristics of phenomena, and not of things in themselves.

[1] B. 58, M. 35.

It will be convenient to consider his treatment of s.p.a.ce and time separately, and to begin with his treatment of s.p.a.ce. It is necessary, however, first of all to refer to the term 'form of perception'. As Kant conceives a form of perception, it involves three ant.i.theses.

(1) As a _form_ of perception it is opposed, as a way or mode of perceiving, to particular perceptions.

(2) As a form or mode of _perception_ it is opposed to a form or mode of _conception_.

(3) As a form of _perception_ it is also opposed, as a way in which we apprehend things, to a way in which things are.

While we may defer consideration of the second and third ant.i.theses, we should at once give attention to the nature of the first, because Kant confuses it with two other ant.i.theses. There is no doubt that in general a _form_ of perception means for Kant a general capacity of perceiving which, as such, is opposed to the actual perceptions in which it is manifested. For according to him our spatial perceptions are not foreign to us, but manifestations of our general perceiving nature; and this view finds expression in the a.s.sertion that s.p.a.ce is a form of perception or of sensibility.[2]

[2] Cf. B. 43 init., M. 26 med.

Unfortunately, however, Kant frequently speaks of this form of perception as if it were the same thing as the actual perception of empty s.p.a.ce.[3] In other words, he implies that such a perception is possible, and confuses it with a potentiality, i. e. the power of perceiving that which is spatial. The confusion is possible because it can be said with some plausibility that a perception of empty s.p.a.ce--if its possibility be allowed--does not inform us about actual things, but only informs us what must be true of things, if there prove to be any; such a perception, therefore, can be thought of as a possibility of knowledge rather than as actual knowledge.

[3] e. g. B. 34, 35, M. 22; B. 41, M. 25; _Prol._ ---- 9-11.

The commonest expression of the confusion is to be found in the repeated a.s.sertion that s.p.a.ce is a pure perception.

The second confusion is closely related to the first, and arises from the fact that Kant speaks of s.p.a.ce not only as a form of _perception_, but also as the form of _phenomena_ in opposition to sensation as their matter. "That which in the phenomenon corresponds to[4] the sensation I term its matter; but that which effects that the manifold of the phenomenon can be arranged under certain relations I call the form of the phenomenon. Now that in which alone our sensations can be arranged and placed in a certain form cannot itself be sensation.

Hence while the matter of all phenomena is only given to us _a posteriori_, their form [i. e. s.p.a.ce] must lie ready for them all together _a priori_ in the mind."[5] Here Kant is clearly under the influence of his theory of perception.[6] He is thinking that, given the origination of sensations in us by the thing in itself, it is the business of the mind to arrange these sensations spatially in order to attain knowledge of the spatial world.[7] s.p.a.ce being, as it were, a kind of empty vessel in which sensations are arranged, is said to be the form of phenomena.[8] Moreover, if we bear in mind that ultimately bodies in s.p.a.ce are for Kant only spatial arrangements of sensations,[9] we see that the a.s.sertion that s.p.a.ce is the form of phenomena is only Kant's way of saying that all bodies are spatial.[10] Now Kant, in thus a.s.serting that s.p.a.ce is the form of phenomena, is clearly confusing this a.s.sertion with the a.s.sertion that s.p.a.ce is a form of perception, and he does so in consequence of the first confusion, viz. that between a capacity of perceiving and an actual perception of empty s.p.a.ce. For in the pa.s.sage last quoted he continues thus: "I call all representations[11] _pure_ (in the transcendental sense) in which nothing is found which belongs to sensation. Accordingly there will be found _a priori_ in the mind the pure form of sensuous perceptions in general, wherein all the manifold of phenomena is perceived in certain relations. This pure form of sensibility will also itself be called _pure perception_. Thus, if I abstract from the representation of a body that which the understanding thinks respecting it, such as substance, force, divisibility, &c., and also that which belongs to sensation, such as impenetrability, hardness, colour, &c., something is still left over for me from this empirical perception, viz. extension and shape. These belong to pure perception, which exists in the mind _a priori_, even without an actual object of the senses or a sensation, as a mere form of sensibility." Here Kant has pa.s.sed, without any consciousness of a transition, from treating s.p.a.ce as that in which the manifold of sensation is arranged to treating it as a capacity of perceiving.

Moreover, since Kant in this pa.s.sage speaks of s.p.a.ce as a perception, and thereby identifies s.p.a.ce with the perception of it,[12] the confusion may be explained thus. The form of phenomena is said to be the s.p.a.ce in which all sensations are arranged, or in which all bodies are; s.p.a.ce, apart from all sensations or bodies, i. e. empty, being the object of a pure perception, is treated as identical with a pure perception, viz. the perception of empty s.p.a.ce; and the perception of empty s.p.a.ce is treated as identical with a capacity of perceiving that which is spatial.[13]

[4] 'Corresponds to' must mean 'is'.

[5] B. 34, M. 21.

[6] Cf. pp. 30-2.

[7] It is impossible, of course, to see how such a process can give us knowledge of the spatial world, for, whatever bodies in s.p.a.ce are, they are not arrangements of sensations.

Nevertheless, Kant's theory of perception really precludes him from holding that bodies are anything else than arrangements of sensations, and he seems at times to accept this view explicitly, e. g. B. 38, M. 23 (quoted p. 41), where he speaks of our representing sensations as external to and next to each other, and, therefore, as in different places.

[8] It may be noted that it would have been more natural to describe the particular shape of the phenomenon (i. e. the particular spatial arrangement of the sensations) rather than s.p.a.ce as the form of the phenomenon; for the matter to which the form is opposed is said to be sensation, and that of which it is the matter is said to be the phenomenon, i. e.

a body in s.p.a.ce.

[9] Cf. note 4, p. 38.

[10] Cf. _Prol._ -- 11 and p. 137.

[11] Cf. p. 41, note 1.

[12] Cf. p. 51, note 1.

[13] The same confusion (and due to the same cause) is implied _Prol_. -- 11, and B. 42 (b), M. 26 (b) first paragraph. Cf. B. 49 (b), M. 30 (b).

The existence of the confusion, however, is most easily realized by asking, 'How did Kant come to think of s.p.a.ce and time as the _only_ forms of perception?' It would seem obvious that the perception of _anything_ implies a form of perception in the sense of a mode or capacity of perceiving. To perceive colours implies a capacity for seeing; to hear noises implies a capacity for hearing. And these capacities may fairly be called forms of perception. As soon as this is realized, the conclusion is inevitable that Kant was led to think of s.p.a.ce and time as the only forms of perception, because in this connexion he was thinking of each as a form of phenomena, i. e. as something in which all bodies or their states are, or, from the point of view of our knowledge, as that in which sensuous material is to be arranged; for there is nothing except s.p.a.ce and time in which such arrangement could plausibly be said to be carried out.

As has been pointed out, Kant's argument falls into two main parts, one of which prepares the way for the other. The aim of the former is to show _firstly_ that our apprehension of s.p.a.ce is _a priori_, and _secondly_ that it belongs to perception and not to conception. The aim of the latter is to conclude from these characteristics of our apprehension of s.p.a.ce that s.p.a.ce is a property not of things in themselves but only of phenomena. These arguments may be considered in turn.

The really valid argument adduced by Kant for the _a priori_ character of our apprehension of s.p.a.ce is based on the nature of geometrical judgements. The universality of our judgements in geometry is not based upon experience, i. e. upon the observation of individual things in s.p.a.ce. The necessity of geometrical relations is apprehended directly in virtue of the mind's own apprehending nature.

Unfortunately in the present context Kant ignores this argument and subst.i.tutes two others, both of which are invalid.

1. "s.p.a.ce is no empirical conception[14] which has been derived from external[15] experiences. For in order that certain sensations may be related to something external to me (that is, to something in a different part of s.p.a.ce from that in which I am), in like manner, in order that I may represent them as external to and next to each other, and consequently as not merely different but as in different places, the representation of s.p.a.ce must already exist as a foundation.

Consequently, the representation of s.p.a.ce cannot be borrowed from the relations of external phenomena through experience; but, on the contrary, this external experience is itself first possible only through the said representation."[16] Here Kant is thinking that in order to apprehend, for example, that A is to the right of B we must first apprehend empty s.p.a.ce. He concludes that our apprehension of s.p.a.ce is _a priori_, because we apprehend empty s.p.a.ce _before_ we become aware of the spatial relations of individual objects in it.

[14] _Begriff_ (conception) here is to be understood loosely not as something opposed to _Anschauung_ (perception), but as equivalent to the genus of which _Anschauung_ and _Begriff_ are species, i. e. _Vorstellung_, which maybe rendered by 'representation' or 'idea', in the general sense in which these words are sometimes used to include 'thought' and 'perception'.

[15] The next sentence shows that 'external' means, not 'produced by something external to the mind', but simply 'spatial'.

[16] B. 38, M. 23-4.

To this the following reply may be made. (_a_) The term _a priori_ applied to an apprehension should mean, not that it arises prior to experience, but that its validity is independent of experience. (_b_) That to which the term _a priori_ should be applied is not the apprehension of empty s.p.a.ce, which is individual, but the apprehension of the nature of s.p.a.ce in general, which is universal. (_c_) We do not apprehend empty s.p.a.ce before we apprehend individual spatial relations of individual bodies or, indeed, at any time. (_d_) Though we come to apprehend _a priori_ the nature of s.p.a.ce in general, the apprehension is not prior but posterior in time to the apprehension of individual spatial relations. (_e_) It does not follow from the temporal priority of our apprehension of individual spatial relations that our apprehension of the nature of s.p.a.ce in general is 'borrowed from experience', and is therefore not _a priori_.