His view that the demands of Practice are so searching that knowledge cannot organise itself too profoundly or too systematically in order to meet them, suggest so close a kinship between Practice and Thought, and makes Practice so expressive of the Ideal, that the Theory of Practice becomes ultimately indistinguishable from a Theory of Aspirations and Ideal Values.

Professor Muscio has warned us in his lucid way that a definition of "the philosophy I hold to be true" should not be confused with the definition of "philosophy in general." My only fear is lest conformity with the warning may not give too abstract a view of Philosophy. Should we not, following Hegel once again, endorse his contention that the best definition of Philosophy is that which the History of Philosophy gives through its own self-criticism? In this case all the philosophies held to be true, each in its own place and connection contribute vitally to the systematic conception of Philosophy in General. If, in our anxiety not to be personal we cut down the distinctive inspirations of A, B, and C, we may leave standing no more than the common bole and root, with all the growing points sacrificed, and with them, the instructive differences in viewpoint. It is, of course, arrogant to picture forth one's own philosophy and then label it Philosophy simpliciter, but might we not perhaps agree in recognising that the true meaning of Philosophy must be sought in the spiritual bond which unites in one inclusive organisation all the sincere and enlightened endeavours of the human spirit to express in terms of Thought its love of the Ideal and its sense of Reality?

256

THE EMERGENCE OF RELATIVITY IN A. N. WHITEHEAD'S PHILOSOPHY.

By

E. V. MILLER, Auckland, New Zealand.*

T is the intention of scientific workers to base the system of knowledge which they are engaged in building up on the solid ground of Nature, on experience, on accurate observation, and to eschew the unsafe methods of metaphysics. It is the belief, too, of many, perhaps of the majority, of these workers that in the development of scientific knowledge this condition is scrupulously observed. On the other hand, from mathematicians, from philosophers, and from the more philosophic minded of the scientific workers themselves, there come drastic criticisms of the structure of scientific knowledge, attacking the fundamental assumptions on which that structure is reared.

Especially is this the case with regard to the notions of space and time which have held unquestioned sway from time immemorial until the beginning of this century. I refer to the concepts of space and time as entirely independent of each other; independent also of Nature, which was conceived of as something taking place in space and in time, in such a manner that if Nature disappeared time and space could still be thought of as existing.

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During the past thirty or forty years the progress of science itself has revealed flaws in the foundations of knowledge. The theory of relativity, the most notable advance in scientific thought since Newton's day, might be described as the result of a resolute facing of these flaws; as a determined application of the observational criterion of science to conceptions which had been masquerading as facts of experience. Even before the day of relativity the relational theory of space was an admission that we cannot know space without matter or matter without space; but such interdependence was not extended to time and matter, or time and space. Relativity made the further admission that time, so far from being independent of Nature, is as much an essential part of it as space, and cannot rightly be thought of without it.

One of the most notable of the modern critics of the groundwork of science is the eminent mathematician and philosopher, A. N. Whitehead, Professor of Applied Mathematics in the Imperial College of Science and Technology.

*Read before the Australasian Association for the Advancement of Science, January, 1923.

In two important works, entitled "An Enquiry Concerning the Principles of Natural Knowledge" and "The Concept of Nature," Professor Whitehead has put forward a new system of natural philosophy. These works are by no means easy reading, and for that reason it is unlikely that they will quickly become known to scientific workers. Yet the philosophy they contain is, at least in the writer's opinion, of outstanding importance to those students of science who are not content to take without examination the assumptions and concepts inherited from the remote past, as sufficient basis on which to develop the vast and growing system of knowledge which constitutes modern science.

Whitehead's philosophy is an attempt to push the principle of observation and inference all the way; to discard every preconception and start with pure observation. The foundations of his system are always experiences, never thoughts. One might perhaps think that if science has indeed chosen false foundations to build upon, its system of knowledge must be vitiated throughout; and that, therefore, anyone setting out to elaborate a system of knowledge based on entirely new premisses would be attempting the herculean task of producing a complete new system of knowledge differing largely from that with which we are familiar. Now a system of knowledge such as we possess, which has taken centuries to elaborate and the labours of myriads of men of outstanding intelligence to achieve, and which, moreover, has passed the drastic test of practical application, is not one to be condemned off-hand on the ground of apparent inconsistency. To do this would be to fall into error, and this Whitehead avoids. Logicians know more than one way in which valid conclusions may be derived from false premisses.

It is clear that Whitehead takes the results of modern science as a more or less close approximation to the truth about Nature. One of his aims is to show that these results do not imply the validity of our preconceived notions of Space Time and Nature; and another is to show how, starting from elementary ideas and concepts based on what we really experience and not on what we merely think-such concepts form a logical substratum to the existing system of scientific knowledge.

The subject matter of his investigation is Nature; a closed system not involving thought or emotion. Nature is that which is disclosed to us through the senses by the process of what Whitehead calls "sense-awareness, a process not involving the intellect. Sights, sounds, feelings of touch, etc., are the deliverances of sense-awareness. Thought is not involved in such bare experiences, but only in their arrangement in a

rational system. Such disclosure is pure observation, and what is disclosed is presented to the intellect as the raw material for thought to work upon in the elaboration of a system of knowledge of Nature. The deliverances of senseawareness are never precise. Precision is essentially an intellectual requirement and an intellectual achievement. We are never aware of a geometrical point or line, or of an instant of time, or of ideally uniform motion. That is to say, none of these things are met with in Nature. But we are aware of closer and closer approximations to these things, and the mind is able to carry on the process of approximation to the limit of ideal definition.

It is in the consideration of what is disclosed to us by sense-awareness that Whitehead makes one of his main criticisms of the foundations of science; and that is in connection with the concept of matter. The error in this, he says, is a legacy from Greek philosophy, the influence of which "has issued in one long misconception of the metaphysical status of natural entities." He proceeds to explain that the concept of matter as a simple substance in terms of which the course of events could be expressed, has had the unfortunate result that the concept has been distinguished from those sense-perceptions of shape, position, hardness and so on, which alone constitute the relevant observational data, and promoted to be a substratum or cause of these perceptions, while the things really observed, the experienced shape, hardness, etc., have been degraded into mere attributes of the concept. Really the hardness, etc., is the way, and the only way, we have of being aware of a fact of Nature; it is the deliverance of sense-awareness; while the concept formed in the mind, to which we attach the word "matter," is what the intellect abstracts from this same deliverance. It is the intellect's way or one of many possible ways of apprehending the same identical fact. Thus in the current philosophy of science, "what is a mere procedure of the mind in the translation of sense-awareness into discursive knowledge has been transmuted into a fundamental character of Nature." Whitehead goes on to show that the concept of matter as the substratum of our experiences presupposes the independent existence of time and space as that in which Nature exists;-necessary, indeed, to Nature, as is the screen to the moving picture thrown upon it, but as independent of it as the screen is independent of the picture.

The view in which we think of our experiences as existing in time and space, and as being the attributes of an underlying substance also existing in time and space, Whitehead characterises as a muddle. "The whole being of substance

is as a substratum for attributes." Its relation to attributes is that of reality to appearance. If, then, we say that our experiences are in space and time, matter cannot also be in space and time; or at least not in the same space and time.

The intrusion of this idea of reality and appearance into the philosophy of natural science involves a further confusion. The hypothesis referred to is that there is a real nature consisting of atoms, electrons, etc., which, by interaction with the mind, gives rise to the deliverances of our sense-awareness—— warmth, colour, hardness, etc. Whitehead contends vehemently against this dragging in of irrelevant material. The subject of the relation between mind and Nature-the "why" of sense-awareness-belongs to metaphysics. Why should not the red glow of the sunset be as much part of Nature as are the electrons and electric waves by which men of science seek to explain the phenomenon? It is only by the experience of the red glow that we become aware of the phenomenon at all. It seems strange to accord this a lower degree of reality or primacy than that which we attribute to the concepts-electrons, electric waves-arrived at by a process of inference, based on the experience.

Taking Nature, then, as what is posited for us in senseawareness, our description of its most general character is complete when we say that it consists of events and their relations. We might be inclined to think that it is necessary at least to add objects, more or less permanent, to which events happen. But the permanence of any object, even one such as the Great Pyramid, implies no more than the restriction of the observer's span of observation. We can easily find processes in Nature, for example the life-history of a star, beside which such an object takes its place simply as the character of a limited event.

But what are the relations of events? The standpoint of observation again reveals that they are completely generalised in terms of what Whitehead calls "extending over" or "extension." Events may overlap, or one may contain another, or they may be entirely separate. These modes of extension give a structure of events fully expressible in terms of the relations between the elements of a four-dimensional manifold. We are not to think of this as simply a combination of the time, with the space of science with its three dimensions. In the proper order of consideration, these scientific concepts are specifications of the fundamental relation of extension, arising through particular conditions.

Thus it becomes part of the problem to indicate how the manifold has actually come to be specified in this particular way in human thinking. The answer is that the concepts