The Concept of Nature — the Tarner Lectures, 1920

that his knowledge has that character, we can only after making doubly sure that we understand eachp. 39 other — agree to differ. Accordingly the first duty of an expositor in stating a theory in which he disbeheves is to exhibit it as logical. It is not there where his trouble lies. .

Let me summarise the previously stated objections to this theory of nature. In the first place it seeks for the cause of the knowledge of the thing known instead of seeking for the character of the thing known: secondly it assumes a knowledge of time in itself apart from events related in time : thirdly it assumes a knowledge of space in itself apart from events related in space. There are in addition to these objections other flaws in the theory.

Some light is thrown on the artificial status of causal nature in this theory by asking, why causal nature is presumed to occupy time and space. This really raises the fundamental question as to what characteristics causal nature should have in common with apparent nature. Why — on this theory — should the cause which influences the mind to perception have any characteristics in common with the effluent apparent nature? In particular, why should it be in space ? Why should it be in time? And more generally, What do we know about mind which would aliow us to infer any particular characteristics of a cause which should influence mind to particular effects?

The transcendence of time beyond nature gives some slight reason for presuming that causal nature should occupy time. For if the mind occupies periods of time, there would seem to be some vague reason for assuming that influencing causes occupy the same periods of time, or at least, occupy periods which are strictly related to the mental periods. But if the mind does notp. 40 occupy volumes of space, there seems to be no reason why causal nature should occupy any volumes of space. Thus space would seem to be merely apparent in the same sense as apparent nature is merely apparent. Accordingly if science is really investigating causes which operate on the mind, it would seem to be entirely on the wrong tack in presuming that the causes which it is seeking for have spatial relations. Furthermore there is nothing else in our knowledge analogous to these causes which influence the mind to perception. Accordingly, beyond the rashly presumed fact that they occupy time, there is really no ground by which we can determine any point of their character. They must remain for ever unknown.

Now I assume as an axiom that science is not a fairy tale. It is not engaged in decking out unknowable entities with arbitrary and fantastic properties. What then is it that science is doing, granting that it is eifecting something of importance } My answer is that it is determining the character of things known, namely the character of apparent nature. But we may drop the term 'apparent'; for there is but one nature, namely the nature which is before us in perceptual knowledge. The characters which science discerns in nature are subtle characters, not obvious at first sight. They are relations of relations and characters of characters. But for all their subtlety they are stamped with a certain simplicity which makes their consideration essential in unravelling the complex relations between characters of more perceptive insistence.

The fact that the bifurcation of nature into causal and apparent components does not express what we mean by our knowledge is brought before us when we realisep. 41 our thoughts in any discussion of the causes of our perceptions. For example, the fire is burning and we see a red coal. This is explained in science by radiant energy from the coal entering our eyes. But in seeking for such an explanation we are not asking what are the sort of occurrences which are fitted to cause a mind to see red. The chain of causation is entirely different. The mind is cut out altogether. The real question is, When red is found in nature, what else is found there also? Namely we are asking for an analysis of the accompaniments in nature of the discovery of red in nature. In a subsequent lecture I shall expand this line of thought. I simply draw attention to it here in order to point out that the wave-theory of light has not been adopted because waves are just the sort of things which ought to make a mind perceive colours. This is no part of the evidence which has ever been adduced for the wave-theory, yet on the causal theory of perception, it is really the only relevant part. In other words, science is not discussing the causes of knowledge, but the coherence of knowledge. The understanding which is sought by science is an understanding of relations within nature.

So far I have discussed the bifurcation of nature in connexion with the theories of absolute time and of absolute space. My reason has been that the introduction of the relational theories only weakens the case for bifurcation, and I wished to discuss this case on its strongest grounds.

For instance, suppose we adopt the relational theory of space. Then the space in which apparent nature is set is the expression of certain relations between the apparent objects. It is a set of apparent relations betweenp. 42 apparent relata. Apparent nature is the dream, and th apparent relations of space are dream relations, and th space is the dream space. Similarly the space in whic] causal nature is set is the expression of certain rela tions between the causal objects. It is the expressioi of certain facts about the causal activity which is goinj on behind the scenes. Accordingly causal space belong to a different order of reality to apparent space. Henc there is no pointwise connexion between the two an( it is meaningless to say that the molecules of the gras are in any place which has a determinate spatial relatioi to the place occupied by the grass which we see. Thi conclusion is very paradoxical and makes nonsense o all scientific phraseology. The case is even worse if w admit the relativity of time. For the same argument apply, and break up time into the dream time and causa time which belong to different orders of reality.

I have however been discussing an extreme form o the bifurcation theory. It is, as I think, the mos defensible form. But its very definiteness makes it th more evidently obnoxious to criticism. The intermediat form allows that the nature we are discussing is alway the nature directly known, and so far it rejects th bifurcation theory. But it holds that there are psychi additions to nature as thus known, and that thes additions are in no proper sense part of nature. Fo example, we perceive the red biUiard ball at its prope time, in its proper place, with its proper motion, wit its proper hardness, and with its proper inertia. Bi] its redness and its warmth, and the sound of the clic as a cannon is made off it are psychic additions, namely secondary qualities which are only the mind's wa of perceiving nature. This is not only the vaguelp. 43 prevalent theory, but is, I believe, the historical form of the bifurcation theory in so far as it is derived from philosophy. I shall call it the theory of psychic additions.

This theory of psychic additions is a sound commonsense theory which lays immense stress on the obvious reality of time, space, solidity and inertia, but distrusts the minor artistic additions of colour, warmth and sound.