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Chapter IX: Motion; and the Categories in General

The category of motion.

The last in our list of categories is Motion itself, along with Space and Time which are in fact always equivalent to motion, though they may be taken provisionally in separation. The question may reasonably be raised whether motion is a category at all and not rather the lowest form of empirical existence, for all such existents are motions and complexes of motions. But in fact, though every empirical existent is some sort of motion or other, it is the sort of motion which it is that makes it empirical: whether a straight line or a triangle or a wave-motion such as that of sound or light or the neural movement that corresponds to a sensation as enjoyed. That it is a motion or a space or a time is a priori or non-empirical; and in fact the category of motion is but another expression of the fact that every existent is a piece of Space-Time. But the category is not Motion, taken as equivalent to Spacer-Time as a whole, nor are Space or Time as wholes either of them a category, as it will be the office of the succeeding chapter to explain at such length as may now seem necessary. Space-Time is the one stuff of which all things are made and is not itself a category but a singular, to which terms applicable to things are applied only through the necessities of speech. Accordingly the category we are now dealing with is more properly described as a motion or a space or a time, or by their abstract terms—motion, spatiality, temporality. Everything is a motion, a space-time.

It might be objected that a motion or a bit of Space-Time is a really existent concrete thing and therefore cannot be a category. Such an objection would imply a complete misunderstanding of the nature of categories. They are not expressing mere adjectives of things, but concrete determinations of every space-time. Existence is the occupation of any space-time. Universality for all its abstract name is a concrete plan of arrangement of space-time, relations are connections which are themselves space-times. Abstract characters are separations made by us from concrete things; but what we are referring to are concrete determinations of things. There is therefore no difficulty from this point of view in treating motion or a motion as categorial. A more serious objection would be this: we must recognise that a motion has a character allied to and of the same kind as quality. There is a motion-quality as there is redness or sweetness. Motion is not a succession of point-instants, but rather a point-instant is the limiting case of a motion. So far we have seen Mr. Bergson to be right in his protest. But while all other, empirical, qualities are correlated with motions, the ‘quality’ motion is purely spatio-temporal, that of being a space-time. There is nothing but the spatio-temporal fact; there is nothing superinduced upon it. The quality of motion which a motion possesses in its indivisible character is, if I may repeat a phrase, a limiting case of empirical quality. It might be called a categorial quality were it not that, as will presently be stated, quality, that is empirical quality, is not categorial at all. Once more the exigencies of language constrain us int using such terms as best we can find for describing the indescribable. For motion is elementary and there is nothing simpler.

I follow therefore the guidance of Plato in reckoning motion as a category. For Plato it is one of his “greatest kinds of beings,” which are what we call categories. Unfortunately he combines it in a pair with rest, which is not an independent category but only means, as we have seen, the absence of comparative motion in reference to some given motion, and is in fact a relative term. For Plato indeed the doubt we have raised as to whether motion is a category at all, or only the first form of empirical existent, could not arise. Even if we are entitled to consider the Timaeus as much as the Sophist as representing his own view and not merely that of his Pythagorean friends, motion must still be for him a category. For the matrix of becoming, the matter of things, is not for him as for us Space-Time but only Space, and movement requires to account for it a category of motion.

Thus a motion in so far as it is a particular sort of motion is an empirical existent. In so far as it has the character of motion, that character is categorial. According to the sense in which, the phrase ‘a motion’ is taken, it means a category or an empirical existent. Motion is thus the border-line between the categorial and the empirical region. Our discussion serves to point the truth that categories and empirical characters are. not separated by a hard-and-fast distinction as Kant supposed. It is rather the distinction between what is pervasive in experience and what is variable and not pervasive. For empirical things are complexes of that very Space-Time of which the categories are the fundamental characters. Accordingly the categories can be and have been studied by the same so-called empirical or experiential method as empirical things are. To this point I shall return again.

Grades of the categories.

At the same time the discussion leads us further to a matter of great importance as well as difficulty, namely the relation of the categories to one another. There are grades of rank within them. Motion is more complex than all the rest and includes them. It communicates with all the others. A motion is a substance and exists and is in relation to other motions. We seem to have three grades within the categories. The major categories are the first four—existence, universality, relation, and order. These communicate with each other as has been seen. Existence is different from other existence. As universal a thing is of the same sort as other particulars and different from another sort of particulars. Relation exists and has in turn universality, in the same sense as a thing is universal. The next group of categories—substance, quantity, number, etc.—communicate with each other and with the major group, but the major group do not communicate with them. Thus a substance is in a relation of causality with other substance, and it exists. But existence is not a substance, nor is relation necessarily causal, it may be a relation of number. Perhaps it might be urged that an existent is also a substance. Yes, but its bare existence, its mere occupation of Space and Time, is not equivalent to substantial occupation. A substance is universal, but a universal as such is not a substance. In fact that it is a substance is the error which underlies the notion of the ‘concrete universal’: when we treat a universal as a singular existent we are going beyond universality to substance.

Motion forms the last or third group of the categories. It presupposes the other categories and communicates with them. But they do not communicate with it. Even substance is not itself motion, though every thing besides being substance is motion. Substance represents motion only in respect of its persistent occupation of space through a lapse of time; but it does not include quantity, nor intensity, nor number. Whereas in motion the full tale of the fundamental determinations of Space-Time is told and motion is consequently the totality of what can be affirmed of every space-time.

Perhaps the above description may serve as a gloss upon Plato's conception of the communion of the greatest forms with one another; how vastly more important such intrinsic communication is than the mere overlapping of different universals in a thing which is say both man and black; and how distinct it is from the participation of a particular in its universal; while at the same time, when the universal is taken to be the plan of the particular spatio-temporal configuration which its particular is, we can see how the participation of the particular in the universal is illuminated by the intercommunion within the world of forms—as indeed is implied in Plato's own doctrine of the forms as the union of the form of number with the indeterminate dyad.1

Besides these categories proper, we shall find that there is yet another group of characters belonging to empirical existents. They are relations arising out of the nature of Space-Time which subsist between existents, but they differ from the categories proper, in presuming that there are empirical things in existence. They concern the connection of empirical things with one another; and may perhaps be spoken of as derived or even empirical categories. These form the subject-matter of the following Book.

It should be added that in speaking of the minor categories of substance, number, etc., that is of the second order of categories as depending on ‘relation’ of their two elements of Space and Time to one another, I have used the term relation from the poverty of language. There is strictly speaking no relation between a time and a space, for relations subsist only between existents, and Space and Time are only provisionally separated features in Space-Time. But ‘relation’ having been used of existents is extended so as to cover any connection. The connection is not a relation but a given feature of any space-time and is only called a relation by analogy. Similarly though the qualities of a substance are related to each other in the strict sense, it is only by an extension of the term that substance is said to be ‘related’ to its qualities, or again, as we have seen before, a universal is said to be related to its particulars, as if the universal could exist by itself, whereas it is the particulars which are related to one another by the relation of identity of sort arising out of their plan.

Pointinstants and infinites.

The categories apply obviously to all finites in the ordinary sense of that term; but they apply also to everything empirical, everything which is not the whole of Space-Time but a part of it. Thus they apply to what I have called empirical infinites, like the infinite numbers, or as we shall see later to the infinite deity, because these are not the whole of Space-Time. However much an infinite number is conceptual, it is rooted in Space-Time like all numbers, and to that radical connection with the common matrix of becoming owes the reality which it possesses. But the empirical infinites offer less difficulty than the point-instants themselves. The categories have been illustrated from point—instants as well as from ordinary things or complexes of pure events. They exist, have universality, and substance, and the like. Even the categories of quantity and number belong to them and that of whole and parts, when point-instants are considered as limiting cases. They are empirical like the infinites, for each point-instant has its own individual character, is a ‘this.’ Yet since they are the elements of Space-Time which is the source of all categories, they illustrate that intimate connection of the non-empirical and the empirical which will be touched on less briefly in the following chapter. But they cannot be treated as finites, regarded as having a separate existence like ordinary finites. That would be to introduce the notion of the real self-subsistent infinitesimal; which is inadmissible. Point-instants are real but their separateness from one another is conceptual. They are in fact the elements of motion and in their reality are inseparable from the universe of motion; they are elements in a continuum. So far from being finites, they are the constituents which are arrived at as the result of infinite division and belong to the same order as the infinites. Consequently they must be regarded not as physical elements like the electrons, but as metaphysical elements, as being the elementary constituents of Space-Time or Motion. Real they are, but if the apparent contradiction may be pardoned, they are ideal realities. In any case they are not apprehended by us purely through sense, but with the aid of conception and by some other mental function yet to be discussed. I do not attempt to minimise the difficulties of this statement, which may I trust be removed or lessened as we proceed. My object here is only to point out that they and the empirical infinites alike are contained within the one original matrix and share the characters which every portion of it possesses. There are empirical elements and empirical infinites, and both are empirical and both in their degree real and yet ideal. Thought if it is correct does not deprive its objects of reality. But reality makes room for ideal objects supposing them to be always in touch with Space Plato distinguishes motion into two sorts, translation or Time; and this both sets of exceptional cases are, the point-instants as constituents of Space-Time, the infinites as a special class of complexes within it.2

Quality not a category.

Our list of categories omits two notions which have pretensions to be accounted categories, quality and change, and the omission must be justified. I will begin with quality, for convenience, though change is so closely related to motion, that it would seem to have prior right. Quality is not a category but an empirical generalisation of the various specific qualities of things, or a collective name for them all. It is not open to me to say that there is no discoverable determination of Space-Time as such which is called quality, as there is one which is called quantity; for this would be begging the question. But it is open to me to ask, is there any pervasive determination of things on the strength of which we can say the thing has quality? for otherwise quality would not be a category of things. Now to this question the answer is that there is none. We know from experience that there are qualities—red, hard, fragrant, sweet, life—corresponding to certain sorts of spatio-temporal complex. But experience does not acquaint us with quality as such; as it does make us acquainted with quantity or substance as such. It is not relevant to point to what we have ourselves called the quality of motion, for this quality, empirical as it is, is the limit between the non-empirical and the empirical, where the two are indistinguishable. Were there no empirical qualities we should not need to speak of the motion-quality at all. Quality is to specific qualities as colour is to red, green, and blue. It is a collective name for them but not their universal. It may gravely be doubted whether there is any plan of colours which may be called colour, which is modified and specified in red, green, and blue as the plan of man is modified in European and Mongolian man. But even if this could be maintained in the case of colour, it cannot be held that there is any plan underlying red and hard and life which is modified into these specific qualities.

Contrast quality with quantity. Quantity as such is a real determination of things of which definite quantities are modifications or copies, which participate in the universal or plan. The same thing is true of the other categories. But it is not true of quality. It may be answered that everything possesses some quality or other, and therefore quality is categorial; everything is a complex of Space-Time and to complexity corresponds quality, it will be said, upon our own showing. But the objection does not hit the mark. Complexity in Space-Time makes everything a complex, but not a quality. It is specific sorts of complexes which are hard or sweet. Complexity as such is not a qualitative but a quantitative or purely spatio-temporal determination. Let us for the sake of definiteness revert to colours. The quality of the colour varies with the wave-length of the vibration. Now every colour has some wave-length or other. This is its universal determination as a complex of motion. But length of wave is a quantity and not a quality. When the length is definite there is colour. But length of wave as such has no colour as such. Or to revert to the general question irrespective of the illustration from colour: all portions of Space-Time are empirical complexes. But we may not therefore say that ‘empirical complex’ is a category. For being empirical is only a collective designation of empirical things. In so far as everything is empirical it is not categorial. There is no category of empiricity which pervades all empirical things. There are only empirical things. In the same way there are red and green and hard and sweet and life and mind; and these are qualities. But there is no universal, quality. Quality is therefore not categorial but empirical. Kant himself though he regarded quality as a category could only use it in experience, could only schematise it, in the form of intensive quantity, which is as good as saying that as quality it was useless as a category. The truth is, it is not a category at all.

Change not a category.

There are two reasons why change cannot be regarded as a category. The first is that it is not pervasive for there may be persistence without change, as in the persistence of a quality, or, if the possibility of this be doubted, in the case of a uniform motion. But the more important reason is that change always involves empirical elements. It is a transition from one empirical determination to another. Primarily change is change of quality, and quality is always empirical. We may, it is true, also have change in quantity as in the velocity of a motion; or a change in direction. But even here it is a transition from one empirical determination of quantity to another. Now a category implies no empirical determination in the finites to which it applies. For instance, relation is a category and an empirical relation is between empirical existents, e.g. father and son. But the category relation does not depend on the empirical character of its terms but on their categorial character of existents. Change on the other hand implies in its nature that that from which the change takes place and that to which it proceeds are empirical.

Change is not mere difference; but the passage from something to something different. A change of quality is more than a difference of quality, it is a process from the old quality to the new. A change of mind, a mere change in my sensation, is experienced by me, or is felt, not as the possession of a different decision or a different sensation, but as the passage from the one mental state to the other. Remembering that all existents, no matter what qualities they possess, are in the end complexes of motion, we may describe change as a species of motion which replaces one set of motions by another; it is grounded in motion and may be described as a motion from one motion to another. The nature of the transitional motion may be different in different cases. Thus one thought may lead on to another and the motion is experienced as a direct transition between the two thoughts. The first thought leads on to the different thought. But the motion of change may not be of this simple and direct kind. Causes at work in my mind may end in displacing one thought from its prominence or activity in my mind. When the pale skin blushes and changes in quality from white to red, there is no direct transition from the motions correlative to whiteness to the new set, but some cause is at work, some motion, which ends in the displacement of the white motions by the red. Where a motion changes in velocity or direction, it is at the instance of some cause or motion. In every case we have not a mere difference but a motion which ends in the substitution of one empirical condition for another.

Change is then not categorial but empirical, and it is an empirical variety of motion, which is still categorial. Accordingly I am unable to accept the doctrine of Mr. Bergson that change is the stuff of things. It can only be so regarded if change is a loose expression for motion. Thus Mr. Bergson writes: “there are changes but there are not things which change; change needs no support. There are movements, but not necessarily invariable objects which move; movement does not imply something which moves.”3 The second proposition is I think true, but not the first. But their juxtaposition as if they were saying the same thing appears to imply that change and movement are identified. This cannot, however, be maintained. Change is change of something else, though it is not necessarily change of anything that can be called a thing, like a material body. Movement is anterior to things which are complexes of movements, and it is quite true that that movement is a stuff of which things are made and is not a mere relation between things which already exist and are said to move. But while the same may be said of change with respect to certain things, change always implies movement and is movement from one movement to another. Change is an alteration in something else, viz. in movement. For Heraclitus, of whom Mr. Bergson is the modern representative, as for the other Ionians there was a stuff in which change occurred or which embodied change and it was fire. But bare change cannot take the place of fire. On the other hand bare motion or Space-Time can, and change is an empirical form of that stuff.4

The categories have no origin.

The categories then being the fundamental determinations of Space-Time are the pervasive features of the experienced world. According to our hypothesis things are complexes of Space-Time, and we have seen relations are spatio-temporal connections between them. Nothing therefore but exhibits categorial features; nothing therefore but obeys the principles in which these features reappear in the form of judgments. Everything has being and is a substance, every event has a cause, everything is related to something else, by way of quantity or causality or difference or otherwise. To the question whether there are privileged or a priori parts of experience, the answer therefore is that there are. To the question whether these privileged elements are due to mind or are in any peculiar way the contribution of mind, or imposed by mind on the objects of experience, the answer is that they are not. On the contrary the categories enter into mind as they enter into the constitution of everything else. The mind being a highly developed spatio-temporal complex, that is to say being in its simplest and ultimate expression such, is an existent, a substance, a cause, numerable, and its acts have intensity, and affect each other causally and reciprocally. To the question whether the a priori characters of the world are derived in some manner from experience of things or are primordial and ultimate, the answer is that they are primordial; they do not come into being otherwise than as all things come into being and because things come into being. All things come into being endowed with the categories and with all of them. They are the determinations of all things which arise within Space-Time, which is the matrix of things, “the nurse of becoming.”

On this conception, the time-honoured controversy on the origin of a priori ideas and principles becomes superfluous, or, if that phrase may sound too harsh to be compatible with the reverence due to great names in philosophy and psychology, these ideas have their origin in Space-Time itself. The controversy owes its fascination to the intrusion of mind. The very use of the words, a priori ideas, suggests that these categories are not features of the world, the greatest kinds of beings as Plato called them, but mere mental objects, or perhaps devices or instruments for understanding experience. Accordingly, since the time of Kant, the debate has turned upon how we acquire these ideas, since there can hardly be a doubt that we have them. Kant is himself in some degree responsible for this result. We have seen that for him the categories are the binding cement of knowledge, whereby the mere empirical material of knowledge becomes in the proper sense experience. Not finding this binding substance in the empirical materials themselves he referred it to the mind, not to mind in its personal or empirical capacity as an experienced object, as something which is made up of psychical states or processes in the same way as a physical object is made up of physical material; but in its impersonal capacity as the subject of knowledge, which knowledge is not merely like an idea of Locke and his followers the possession of an individual but open to all minds. This, as I have said, was his method of expressing, and perhaps the only method open to him of expressing, the impersonality of knowledge, of real experience as distinct from the objects which may occur to you or me and not to another. But though he rightly saw that the empirical or variable element in experience was distinct from the a priori element, he did not see that what was empirical was in fact in the same kind as the non-empirical, that it was in itself the modifications of the non-empirical. As he did not merely distinguish the two but separated them, the categories became an artificial tie between things in a different kind from them. No wonder that he seemed to think of the categories and of Space and Time as tools for working up empirical experience, a “machine shop” in the trenchant but entirely misguided phrase of James. They were not so for him; but since their connection with the empirical material was referred to mind, it remained miraculous that causality or Space should be a part of experience itself as he was all the time insisting.

Kant's solution of the problem was not psychological, though it simulated that form. The problem has since become almost entirely psychological; have we a priori ideas, and how do we come by them? The attempts that have been made to answer the question have been psychologically unsuccessful, and metaphysically they have attained the failure to which, if our hypothesis be correct, they were foredoomed. For these ideas have no history, but lie at the basis of all history, whether history of the mind or of other things. They could not be derived from the experience which the individual has of empirical things. For how could we gather number, for instance, from things, if things were not already numerable? And if they are, our idea of number requires no history except possibly of how it comes to clearness in our minds.

Then biology came to the help of half-hearted empiricism. The individual could not within a life-time acquire from external things through co-ordinated experiences of touch (or sight) and movement the notion of Space. But the acquisitions of a life might be transmitted from father to child, and the accumulated experience of generations might suffice. Thus, while Space or number are a posteriori for the race, derived from the observation of empirical things, they would be a priori for the individual who inherits the results of centuries of past experience. The biology, legitimate at the time the theory was formulated, has since become more than suspect. But even if it were correct, how could experiences which were not themselves spatial or numerical, no matter through how many generations they were inherited, come to feel or look like space or number?

To Spencer's experiment succeeded the brilliant hypothesis of William James, contained in the concluding chapter of his Psychology Some of our experiences come to us through the front-door, by way of sense; some through the back-door, by way of our cerebral (and mental) disposition. We see yellow when a field of buttercups is presented to our eyes; but we also see yellow when we are dosed with the drug santonin. The categories and all a priori ideas come to us by this back-door method. By a fortunate variation a brain is born whose mind envisages the world causally or numerically, and being successful in its reactions to a world which is causal and numerical, its kind prevails and peoples the earth. The biology is above reproach, but the theory is as defective as Kant's and, ironically enough, its defects are much of the same sort. Unnecessary as psychology, it will not bear examination as metaphysics. It is assumed that I do not see causality or number in the empirical object. But if so the analogy of the yellow which we get either from the buttercup or from the optic centres dosed with the drug is unavailable. In the first place there is, so far as I am aware, no evidence that a person who had never seen yellow from the buttercup or other yellow objects would see yellow at all from santonin. If the brain had not already functioned so as to see what we call a yellow thing, would the stimulation of the optic centre from within suffice? This is a very seasonable doubt, which, however, is too much connected theoretically with a particular view of sensation to be dwelt on further at this stage. Let us, however, suppose it to be possible; how would it help? Let there be a mind which, when the optic centre is stimulated in a special way, whether from within or from without, sees yellow, and let it, not having seen a buttercup before, see a buttercup. It would see the shape of the buttercup and feel and smell the flower, and it would see yellow. But why should it see the buttercup yellow? Why attach the yellowness it sees to the buttercup? Now the same question arises precisely with the a priori ideas. My brain when stimulated in a certain way thinks number or causality. But why does it attach number to this pile of shot, or causality to this murderer, if there is no number or causality written on the face of the empirical object? You will have frontdoor experience and back-door experience; but the problem to be solved is how the front-door perceptions come to be interpreted by the back-door ideas. If there are clues to guide the mind then the back-door ideas are not wanted. If there are none they are useless. Kant is avenged; the mind is a veritable machine-shop of a priori ideas with which it fashions outward experience; the accuser commits the very fault with which he unjustly charged the accused. And, over and above, the question remains which must not be answered here; could any habit of mental action, due to endowment of brain, give us apprehension of number or causality, apart from the causality it enjoys in itself, unless it has exercised that causal habit at the call of some external causality? The reservation contained in the words apart from its enjoyment of itself was not needed in the case of the yellow. For there the mind does not enjoy itself as yellow when the optic centre is drugged, but sees yellow in the same way as it sees a buttercup yellow.

The truth is, that no fortunate variation is needed to account for our envisaging the external world as causal and numerical. The brain and the mind themselves enjoy causality both internally in the relations of their processes and in their relation to things outside the brain or mind, and things outside are already causal and are so apprehended by the mind. The fortunate variations of brain or mind are not those which apprehend cause or number, for these belong to brain or mind as they belong to all things in space-time. The fortunate variations are those empirical ones, those special twists of talent or genius or sensibility, by which an individual discovers the law of gravitation or produces Hamlet or the Choral Symphony. We no more need a special gift for number than we need a special gift for yellow. In the one case we need eyes; in the other case what we need is consciousness. Indeed, as we shall see more clearly hereafter, just because number and cause are categorial we do not need a special organ like eyes to apprehend them. We shall see that in contemplating causality outside itself the mind is aware in enjoyment of its own causality.

  • 1.

    See before, ch. viii. p. 315.

  • 2.

    The subject is returned to in Bk. IV. ch. i. á propos of the infinite qualified entity God.

  • 3.

    H. Bergson, La Perception du changement (Oxford, 1911), p. 24.

  • 4.

    Plato distinguishes motion into two sorts, translation or movement from place to place (περιφορα); and change or alteration, motion from state to state (αλλοιωσις). Theaet. p. 181b. See Burnet, Gk. Phil. Pt. i. p. 245. I am following Plato, though with differences.