<h2><span class="pagenum" title="Page 26"> </span><SPAN name="Page_26" id="Page_26"></SPAN><SPAN name="CHAPTER_II" id="CHAPTER_II"></SPAN>CHAPTER II <br/> THEORIES OF THE BIFURCATION OF NATURE</h2>
<p>In my previous lecture I criticised the concept of matter as the
substance whose attributes we perceive. This way of thinking of matter
is, I think, the historical reason for its introduction into science,
and is still the vague view of it at the background of our thoughts
which makes the current scientific doctrine appear so obvious. Namely we
conceive ourselves as perceiving attributes of things, and bits of
matter are the things whose attributes we perceive.</p>
<p>In the seventeenth century the sweet simplicity of this aspect of matter
received a rude shock. The transmission doctrines of science were then
in process of elaboration and by the end of the century were
unquestioned, though their particular forms have since been modified.
The establishment of these transmission theories marks a turning point
in the relation between science and philosophy. The doctrines to which I
am especially alluding are the theories of light and sound. I have no
doubt that the theories had been vaguely floating about before as
obvious suggestions of common sense; for nothing in thought is ever
completely new. But at that epoch they were systematised and made exact,
and their complete consequences were ruthlessly deduced. It is the
establishment of this procedure of taking the consequences seriously
which marks the real discovery of a theory. Systematic doctrines of
light and sound as being something proceeding from<span class="pagenum" title="Page 27"> </span><SPAN name="Page_27" id="Page_27"></SPAN> the emitting bodies
were definitely established, and in particular the connexion of light
with colour was laid bare by Newton.</p>
<p>The result completely destroyed the simplicity of the ‘substance and
attribute’ theory of perception. What we see depends on the light
entering the eye. Furthermore we do not even perceive what enters the
eye. The things transmitted are waves or—as Newton thought—minute
particles, and the things seen are colours. Locke met this difficulty by
a theory of primary and secondary qualities. Namely, there are some
attributes of the matter which we do perceive. These are the primary
qualities, and there are other things which we perceive, such as
colours, which are not attributes of matter, but are perceived by us as
if they were such attributes. These are the secondary qualities of
matter.</p>
<p>Why should we perceive secondary qualities? It seems an extremely
unfortunate arrangement that we should perceive a lot of things that are
not there. Yet this is what the theory of secondary qualities in fact
comes to. There is now reigning in philosophy and in science an
apathetic acquiescence in the conclusion that no coherent account can be
given of nature as it is disclosed to us in sense-awareness, without
dragging in its relations to mind. The modern account of nature is not,
as it should be, merely an account of what the mind knows of nature; but
it is also confused with an account of what nature does to the mind. The
result has been disastrous both to science and to philosophy, but
chiefly to philosophy. It has transformed the grand question of the
relations between nature and mind into the petty form of the interaction
between the human body and mind.</p>
<p><span class="pagenum" title="Page 28"> </span><SPAN name="Page_28" id="Page_28"></SPAN>Berkeley’s polemic against matter was based on this confusion introduced
by the transmission theory of light. He advocated, rightly as I think,
the abandonment of the doctrine of matter in its present form. He had
however nothing to put in its place except a theory of the relation of
finite minds to the divine mind.</p>
<p>But we are endeavouring in these lectures to limit ourselves to nature
itself and not to travel beyond entities which are disclosed in
sense-awareness.</p>
<p>Percipience in itself is taken for granted. We consider indeed
conditions for percipience, but only so far as those conditions are
among the disclosures of perception. We leave to metaphysics the
synthesis of the knower and the known. Some further explanation and
defence of this position is necessary, if the line of argument of these
lectures is to be comprehensible.</p>
<p>The immediate thesis for discussion is that any metaphysical
interpretation is an illegitimate importation into the philosophy of
natural science. By a metaphysical interpretation I mean any discussion
of the how (beyond nature) and of the why (beyond nature) of thought and
sense-awareness. In the philosophy of science we seek the general
notions which apply to nature, namely, to what we are aware of in
perception. It is the philosophy of the thing perceived, and it should
not be confused with the metaphysics of reality of which the scope
embraces both perceiver and perceived. No perplexity concerning the
object of knowledge can be solved by saying that there is a mind knowing
it<SPAN name="FNanchor_2_2" id="FNanchor_2_2"></SPAN><SPAN href="#Footnote_2_2" class="fnanchor">[2]</SPAN>.</p>
<div class="footnote"><p><SPAN name="Footnote_2_2" id="Footnote_2_2"></SPAN><span class="label"><SPAN href="#FNanchor_2_2">[2]</SPAN></span> Cf. <i>Enquiry</i>, preface.</p>
</div>
<p>In other words, the ground taken is this: sense-awareness is an
awareness of something. What then is the general character of that
something of which we<span class="pagenum" title="Page 29"> </span><SPAN name="Page_29" id="Page_29"></SPAN> are aware? We do not ask about the percipient or
about the process, but about the perceived. I emphasise this point
because discussions on the philosophy of science are usually extremely
metaphysical—in my opinion, to the great detriment of the subject.</p>
<p>The recourse to metaphysics is like throwing a match into the powder
magazine. It blows up the whole arena. This is exactly what scientific
philosophers do when they are driven into a corner and convicted of
incoherence. They at once drag in the mind and talk of entities in the
mind or out of the mind as the case may be. For natural philosophy
everything perceived is in nature. We may not pick and choose. For us
the red glow of the sunset should be as much part of nature as are the
molecules and electric waves by which men of science would explain the
phenomenon. It is for natural philosophy to analyse how these various
elements of nature are connected.</p>
<p>In making this demand I conceive myself as adopting our immediate
instinctive attitude towards perceptual knowledge which is only
abandoned under the influence of theory. We are instinctively willing to
believe that by due attention, more can be found in nature than that
which is observed at first sight. But we will not be content with less.
What we ask from the philosophy of science is some account of the
coherence of things perceptively known.</p>
<p>This means a refusal to countenance any theory of psychic additions to
the object known in perception. For example, what is given in perception
is the green grass. This is an object which we know as an ingredient in
nature. The theory of psychic additions would treat the greenness as a
psychic addition furnished by the<span class="pagenum" title="Page 30"> </span><SPAN name="Page_30" id="Page_30"></SPAN> perceiving mind, and would leave to
nature merely the molecules and the radiant energy which influence the
mind towards that perception. My argument is that this dragging in of
the mind as making additions of its own to the thing posited for
knowledge by sense-awareness is merely a way of shirking the problem of
natural philosophy. That problem is to discuss the relations <i>inter se</i>
of things known, abstracted from the bare fact that they are known.
Natural philosophy should never ask, what is in the mind and what is in
nature. To do so is a confession that it has failed to express relations
between things perceptively known, namely to express those natural
relations whose expression is natural philosophy. It may be that the
task is too hard for us, that the relations are too complex and too
various for our apprehension, or are too trivial to be worth the trouble
of exposition. It is indeed true that we have gone but a very small way
in the adequate formulation of such relations. But at least do not let
us endeavour to conceal failure under a theory of the byplay of the
perceiving mind.</p>
<p>What I am essentially protesting against is the bifurcation of nature
into two systems of reality, which, in so far as they are real, are real
in different senses. One reality would be the entities such as electrons
which are the study of speculative physics. This would be the reality
which is there for knowledge; although on this theory it is never known.
For what is known is the other sort of reality, which is the byplay of
the mind. Thus there would be two natures, one is the conjecture and the
other is the dream.</p>
<p>Another way of phrasing this theory which I am arguing against is to
bifurcate nature into two divisions,<span class="pagenum" title="Page 31"> </span><SPAN name="Page_31" id="Page_31"></SPAN> namely into the nature apprehended
in awareness and the nature which is the cause of awareness. The nature
which is the fact apprehended in awareness holds within it the greenness
of the trees, the song of the birds, the warmth of the sun, the hardness
of the chairs, and the feel of the velvet. The nature which is the cause
of awareness is the conjectured system of molecules and electrons which
so affects the mind as to produce the awareness of apparent nature. The
meeting point of these two natures is the mind, the causal nature being
influent and the apparent nature being effluent.</p>
<p>There are four questions which at once suggest themselves for discussion
in connexion with this bifurcation theory of nature. They concern (i)
causality, (ii) time, (iii) space, and (iv) delusions. These questions
are not really separable. They merely constitute four distinct starting
points from which to enter upon the discussion of the theory.</p>
<p>Causal nature is the influence on the mind which is the cause of the
effluence of apparent nature from the mind. This conception of causal
nature is not to be confused with the distinct conception of one part of
nature as being the cause of another part. For example, the burning of
the fire and the passage of heat from it through intervening space is
the cause of the body, its nerves and its brain, functioning in certain
ways. But this is not an action of nature on the mind. It is an
interaction within nature. The causation involved in this interaction is
causation in a different sense from the influence of this system of
bodily interactions within nature on the alien mind which thereupon
perceives redness and warmth.</p>
<p>The bifurcation theory is an attempt to exhibit<span class="pagenum" title="Page 32"> </span><SPAN name="Page_32" id="Page_32"></SPAN> natural science as an
investigation of the cause of the fact of knowledge. Namely, it is an
attempt to exhibit apparent nature as an effluent from the mind because
of causal nature. The whole notion is partly based on the implicit
assumption that the mind can only know that which it has itself produced
and retains in some sense within itself, though it requires an exterior
reason both as originating and as determining the character of its
activity. But in considering knowledge we should wipe out all these
spatial metaphors, such as ‘within the mind’ and ‘without the mind.’
Knowledge is ultimate. There can be no explanation of the ‘why’ of
knowledge; we can only describe the ‘what’ of knowledge. Namely we can
analyse the content and its internal relations, but we cannot explain
why there is knowledge. Thus causal nature is a metaphysical chimera;
though there is need of a metaphysics whose scope transcends the
limitation to nature. The object of such a metaphysical science is not
to explain knowledge, but exhibit in its utmost completeness our concept
of reality.</p>
<p>However, we must admit that the causality theory of nature has its
strong suit. The reason why the bifurcation of nature is always creeping
back into scientific philosophy is the extreme difficulty of exhibiting
the perceived redness and warmth of the fire in one system of relations
with the agitated molecules of carbon and oxygen, with the radiant
energy from them, and with the various functionings of the material
body. Unless we produce the all-embracing relations, we are faced with a
bifurcated nature; namely, warmth and redness on one side, and
molecules, electrons and ether on the other side. Then the two factors
are explained as being respectively the cause and the mind’s reaction to
the cause.</p>
<p><span class="pagenum" title="Page 33"> </span><SPAN name="Page_33" id="Page_33"></SPAN>Time and space would appear to provide these all-embracing relations
which the advocates of the philosophy of the unity of nature require.
The perceived redness of the fire and the warmth are definitely related
in time and in space to the molecules of the fire and the molecules of
the body.</p>
<p>It is hardly more than a pardonable exaggeration to say that the
determination of the meaning of nature reduces itself principally to the
discussion of the character of time and the character of space. In
succeeding lectures I shall explain my own view of time and space. I
shall endeavour to show that they are abstractions from more concrete
elements of nature, namely, from events. The discussion of the details
of the process of abstraction will exhibit time and space as
interconnected, and will finally lead us to the sort of connexions
between their measurements which occur in the modern theory of
electromagnetic relativity. But this is anticipating our subsequent line
of development. At present I wish to consider how the ordinary views of
time and space help, or fail to help, in unifying our conception of
nature.</p>
<p>First, consider the absolute theories of time and space. We are to
consider each, namely both time and space, to be a separate and
independent system of entities, each system known to us in itself and
for itself concurrently with our knowledge of the events of nature. Time
is the ordered succession of durationless instants; and these instants
are known to us merely as the relata in the serial relation which is the
time-ordering relation, and the time-ordering relation is merely known
to us as relating the instants. Namely, the relation and the instants
are jointly known to us in our apprehension of time, each implying the
other.</p>
<p><span class="pagenum" title="Page 34"> </span><SPAN name="Page_34" id="Page_34"></SPAN>This is the absolute theory of time. Frankly, I confess that it seems to
me to be very unplausible. I cannot in my own knowledge find anything
corresponding to the bare time of the absolute theory. Time is known to
me as an abstraction from the passage of events. The fundamental fact
which renders this abstraction possible is the passing of nature, its
development, its creative advance, and combined with this fact is
another characteristic of nature, namely the extensive relation between
events. These two facts, namely the passage of events and the extension
of events over each other, are in my opinion the qualities from which
time and space originate as abstractions. But this is anticipating my
own later speculations.</p>
<p>Meanwhile, returning to the absolute theory, we are to suppose that time
is known to us independently of any events in time. What happens in time
occupies time. This relation of events to the time occupied, namely this
relation of occupation, is a fundamental relation of nature to time.
Thus the theory requires that we are aware of two fundamental relations,
the time-ordering relation between instants, and the time-occupation
relation between instants of time and states of nature which happen at
those instants.</p>
<p>There are two considerations which lend powerful support to the reigning
theory of absolute time. In the first place time extends beyond nature.
Our thoughts are in time. Accordingly it seems impossible to derive time
merely from relations between elements of nature. For in that case
temporal relations could not relate thoughts. Thus, to use a metaphor,
time would apparently have deeper roots in reality than has nature. For
we can imagine thoughts related in time without<span class="pagenum" title="Page 35"> </span><SPAN name="Page_35" id="Page_35"></SPAN> any perception of
nature. For example we can imagine one of Milton’s angels with thoughts
succeeding each other in time, who does not happen to have noticed that
the Almighty has created space and set therein a material universe. As a
matter of fact I think that Milton set space on the same absolute level
as time. But that need not disturb the illustration. In the second place
it is difficult to derive the true serial character of time from the
relative theory. Each instant is irrevocable. It can never recur by the
very character of time. But if on the relative theory an instant of time
is simply the state of nature at that time, and the time-ordering
relation is simply the relation between such states, then the
irrevocableness of time would seem to mean that an actual state of all
nature can never return. I admit it seems unlikely that there should
ever be such a recurrence down to the smallest particular. But extreme
unlikeliness is not the point. Our ignorance is so abysmal that our
judgments of likeliness and unlikeliness of future events hardly count.
The real point is that the exact recurrence of a state of nature seems
merely unlikely, while the recurrence of an instant of time violates our
whole concept of time-order. The instants of time which have passed, are
passed, and can never be again.</p>
<p>Any alternative theory of time must reckon with these two considerations
which are buttresses of the absolute theory. But I will not now continue
their discussion.</p>
<p>The absolute theory of space is analogous to the corresponding theory of
time, but the reasons for its maintenance are weaker. Space, on this
theory, is a system of extensionless points which are the relata in
space-ordering relations which can technically be com<span class="pagenum" title="Page 36"> </span><SPAN name="Page_36" id="Page_36"></SPAN>bined into one
relation. This relation does not arrange the points in one linear series
analogously to the simple method of the time-ordering relation for
instants. The essential logical characteristics of this relation from
which all the properties of space spring are expressed by mathematicians
in the axioms of geometry. From these axioms<SPAN name="FNanchor_3_3" id="FNanchor_3_3"></SPAN><SPAN href="#Footnote_3_3" class="fnanchor">[3]</SPAN> as framed by modern
mathematicians the whole science of geometry can be deduced by the
strictest logical reasoning. The details of these axioms do not now
concern us. The points and the relations are jointly known to us in our
apprehension of space, each implying the other. What happens in space,
occupies space. This relation of occupation is not usually stated for
events but for objects. For example, Pompey’s statue would be said to
occupy space, but not the event which was the assassination of Julius
Caesar. In this I think that ordinary usage is unfortunate, and I hold
that the relations of events to space and to time are in all respects
analogous. But here I am intruding my own opinions which are to be
discussed in subsequent lectures. Thus the theory of absolute space
requires that we are aware of two fundamental relations, the
space-ordering relation, which holds between points, and the
space-occupation relation between points of space and material objects.</p>
<div class="footnote"><p><SPAN name="Footnote_3_3" id="Footnote_3_3"></SPAN><span class="label"><SPAN href="#FNanchor_3_3">[3]</SPAN></span> Cf. (for example) <i>Projective Geometry</i> by Veblen and
Young, vol. i. 1910, vol. ii. 1917, Ginn and Company, Boston, U.S.A.</p>
</div>
<p>This theory lacks the two main supports of the corresponding theory of
absolute time. In the first place space does not extend beyond nature in
the sense that time seems to do. Our thoughts do not seem to occupy
space in quite the same intimate way in which they occupy time. For
example, I have been thinking in a room, and<span class="pagenum" title="Page 37"> </span><SPAN name="Page_37" id="Page_37"></SPAN> to that extent my thoughts
are in space. But it seems nonsense to ask how much volume of the room
they occupied, whether it was a cubic foot or a cubic inch; whereas the
same thoughts occupy a determinate duration of time, say, from eleven to
twelve on a certain date.</p>
<p>Thus whereas the relations of a relative theory of time are required to
relate thoughts, it does not seem so obvious that the relations of a
relative theory of space are required to relate them. The connexion of
thought with space seems to have a certain character of indirectness
which appears to be lacking in the connexion of thought with time.</p>
<p>Again the irrevocableness of time does not seem to have any parallel for
space. Space, on the relative theory, is the outcome of certain
relations between objects commonly said to be in space; and whenever
there are the objects, so related, there is the space. No difficulty
seems to arise like that of the inconvenient instants of time which
might conceivably turn up again when we thought that we had done with
them.</p>
<p>The absolute theory of space is not now generally popular. The knowledge
of bare space, as a system of entities known to us in itself and for
itself independently of our knowledge of the events in nature, does not
seem to correspond to anything in our experience. Space, like time,
would appear to be an abstraction from events. According to my own
theory it only differentiates itself from time at a somewhat developed
stage of the abstractive process. The more usual way of expressing the
relational theory of space would be to consider space as an abstraction
from the relations between material objects.</p>
<p>Suppose now we assume absolute time and absolute<span class="pagenum" title="Page 38"> </span><SPAN name="Page_38" id="Page_38"></SPAN> space. What bearing
has this assumption on the concept of nature as bifurcated into causal
nature and apparent nature? Undoubtedly the separation between the two
natures is now greatly mitigated. We can provide them with two systems
of relations in common; for both natures can be presumed to occupy the
same space and the same time. The theory now is this: Causal events
occupy certain periods of the absolute time and occupy certain positions
of the absolute space. These events influence a mind which thereupon
perceives certain apparent events which occupy certain periods in the
absolute time and occupy certain positions of the absolute space; and
the periods and positions occupied by the apparent events bear a
determinate relation to the periods and positions occupied by the causal
events.</p>
<p>Furthermore definite causal events produce for the mind definite
apparent events. Delusions are apparent events which appear in temporal
periods and spatial positions without the intervention of these causal
events which are proper for influencing of the mind to their perception.</p>
<p>The whole theory is perfectly logical. In these discussions we cannot
hope to drive an unsound theory to a logical contradiction. A reasoner,
apart from mere slips, only involves himself in a contradiction when he
is shying at a <i>reductio ad absurdum</i>. The substantial reason for
rejecting a philosophical theory is the ‘absurdum’ to which it reduces
us. In the case of the philosophy of natural science the ‘absurdum’ can
only be that our perceptual knowledge has not the character assigned to
it by the theory. If our opponent affirms that his knowledge has that
character, we can only—after making doubly sure that we understand
each<span class="pagenum" title="Page 39"> </span><SPAN name="Page_39" id="Page_39"></SPAN> other—agree to differ. Accordingly the first duty of an expositor
in stating a theory in which he disbelieves is to exhibit it as logical.
It is not there where his trouble lies.</p>
<p>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.</p>
<p>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
allow us to infer any particular characteristics of a cause which should
influence mind to particular effects?</p>
<p>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 not<span class="pagenum" title="Page 40"> </span><SPAN name="Page_40" id="Page_40"></SPAN> 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.</p>
<p>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
effecting 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.</p>
<p>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 realise<span class="pagenum" title="Page 41"> </span><SPAN name="Page_41" id="Page_41"></SPAN> 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.</p>
<p>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.</p>
<p>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 between<span class="pagenum" title="Page 42"> </span><SPAN name="Page_42" id="Page_42"></SPAN> apparent relata. Apparent nature is the dream, and
the apparent relations of space are dream relations, and the space is
the dream space. Similarly the space in which causal nature is set is
the expression of certain relations between the causal objects. It is
the expression of certain facts about the causal activity which is going
on behind the scenes. Accordingly causal space belongs to a different
order of reality to apparent space. Hence there is no pointwise
connexion between the two and it is meaningless to say that the
molecules of the grass are in any place which has a determinate spatial
relation to the place occupied by the grass which we see. This
conclusion is very paradoxical and makes nonsense of all scientific
phraseology. The case is even worse if we admit the relativity of time.
For the same arguments apply, and break up time into the dream time and
causal time which belong to different orders of reality.</p>
<p>I have however been discussing an extreme form of the bifurcation
theory. It is, as I think, the most defensible form. But its very
definiteness makes it the more evidently obnoxious to criticism. The
intermediate form allows that the nature we are discussing is always the
nature directly known, and so far it rejects the bifurcation theory. But
it holds that there are psychic additions to nature as thus known, and
that these additions are in no proper sense part of nature. For example,
we perceive the red billiard ball at its proper time, in its proper
place, with its proper motion, with its proper hardness, and with its
proper inertia. But its redness and its warmth, and the sound of the
click as a cannon is made off it are psychic additions, namely,
secondary qualities which are only the mind’s way of perceiving nature.
This is not only the vaguely<span class="pagenum" title="Page 43"> </span><SPAN name="Page_43" id="Page_43"></SPAN> 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.</p>
<p>This theory of psychic additions is a sound common-sense 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.</p>
<p>The theory is the outcome of common-sense in retreat. It arose in an
epoch when the transmission theories of science were being elaborated.
For example, colour is the result of a transmission from the material
object to the perceiver’s eye; and what is thus transmitted is not
colour. Thus colour is not part of the reality of the material object.
Similarly for the same reason sounds evaporate from nature. Also warmth
is due to the transfer of something which is not temperature. Thus we
are left with spatio-temporal positions, and what I may term the
‘pushiness’ of the body. This lands us to eighteenth and nineteenth
century materialism, namely, the belief that what is real in nature is
matter, in time and in space and with inertia.</p>
<p>Evidently a distinction in quality has been presupposed separating off
some perceptions due to touch from other perceptions. These
touch-perceptions are perceptions of the real inertia, whereas the other
perceptions are psychic additions which must be explained on the causal
theory. This distinction is the product of an epoch in which physical
science has got ahead of medical pathology and of physiology.
Perceptions of push are just as much the outcome of transmission as are
perceptions of colour. When colour is perceived the nerves of the body
are excited in one way and transmit their message towards the brain, and
when push is perceived<span class="pagenum" title="Page 44"> </span><SPAN name="Page_44" id="Page_44"></SPAN> other nerves of the body are excited in another
way and transmit their message towards the brain. The message of the one
set is not the conveyance of colour, and the message of the other set is
not the conveyance of push. But in one case colour is perceived and in
the other case the push due to the object. If you snip certain nerves,
there is an end to the perception of colour; and if you snip certain
other nerves, there is an end to the perception of push. It would appear
therefore that any reasons which should remove colour from the reality
of nature should also operate to remove inertia.</p>
<p>Thus the attempted bifurcation of apparent nature into two parts of
which one part is both causal for its own appearance and for the
appearance of the other part, which is purely apparent, fails owing to
the failure to establish any fundamental distinction between our ways of
knowing about the two parts of nature as thus partitioned. I am not
denying that the feeling of muscular effort historically led to the
formulation of the concept of force. But this historical fact does not
warrant us in assigning a superior reality in nature to material inertia
over colour or sound. So far as reality is concerned all our
sense-perceptions are in the same boat, and must be treated on the same
principle. The evenness of treatment is exactly what this compromise
theory fails to achieve.</p>
<p>The bifurcation theory however dies hard. The reason is that there
really is a difficulty to be faced in relating within the same system of
entities the redness of the fire with the agitation of the molecules. In
another lecture I will give my own explanation of the origin of the
difficulty and of its solution.</p>
<p>Another favourite solution, the most attenuated form<span class="pagenum" title="Page 45"> </span><SPAN name="Page_45" id="Page_45"></SPAN> which the
bifurcation theory assumes, is to maintain that the molecules and ether
of science are purely conceptual. Thus there is but one nature, namely
apparent nature, and atoms and ether are merely names for logical terms
in conceptual formulae of calculation.</p>
<p>But what is a formula of calculation? It is presumably a statement that
something or other is true for natural occurrences. Take the simplest of
all formulae, Two and two make four. This—so far as it applies to
nature—asserts that if you take two natural entities, and then again
two other natural entities, the combined class contains four natural
entities. Such formulae which are true for any entities cannot result in
the production of the concepts of atoms. Then again there are formulae
which assert that there are entities in nature with such and such
special properties, say, for example, with the properties of the atoms
of hydrogen. Now if there are no such entities, I fail to see how any
statements about them can apply to nature. For example, the assertion
that there is green cheese in the moon cannot be a premiss in any
deduction of scientific importance, unless indeed the presence of green
cheese in the moon has been verified by experiment. The current answer
to these objections is that, though atoms are merely conceptual, yet
they are an interesting and picturesque way of saying something else
which is true of nature. But surely if it is something else that you
mean, for heaven’s sake say it. Do away with this elaborate machinery of
a conceptual nature which consists of assertions about things which
don’t exist in order to convey truths about things which do exist. I am
maintaining the obvious position that scientific laws, if they are true,
are statements about entities<span class="pagenum" title="Page 46"> </span><SPAN name="Page_46" id="Page_46"></SPAN> which we obtain knowledge of as being in
nature; and that, if the entities to which the statements refer are not
to be found in nature, the statements about them have no relevance to
any purely natural occurrence. Thus the molecules and electrons of
scientific theory are, so far as science has correctly formulated its
laws, each of them factors to be found in nature. The electrons are only
hypothetical in so far as we are not quite certain that the electron
theory is true. But their hypothetical character does not arise from the
essential nature of the theory in itself after its truth has been
granted.</p>
<p>Thus at the end of this somewhat complex discussion, we return to the
position which was affirmed at its beginning. The primary task of a
philosophy of natural science is to elucidate the concept of nature,
considered as one complex fact for knowledge, to exhibit the fundamental
entities and the fundamental relations between entities in terms of
which all laws of nature have to be stated, and to secure that the
entities and relations thus exhibited are adequate for the expression of
all the relations between entities which occur in nature.</p>
<p>The third requisite, namely that of adequacy, is the one over which all
the difficulty occurs. The ultimate data of science are commonly assumed
to be time, space, material, qualities of material, and relations
between material objects. But data as they occur in the scientific laws
do not relate all the entities which present themselves in our
perception of nature. For example, the wave-theory of light is an
excellent well-established theory; but unfortunately it leaves out
colour as perceived. Thus the perceived redness—or, other colour—has
to be cut out of nature and made into the reaction of the mind under the
impulse of the actual events of<span class="pagenum" title="Page 47"> </span><SPAN name="Page_47" id="Page_47"></SPAN> nature. In other words this concept of
the fundamental relations within nature is inadequate. Thus we have to
bend our energies to the enunciation of adequate concepts.</p>
<p>But in so doing, are we not in fact endeavouring to solve a metaphysical
problem? I do not think so. We are merely endeavouring to exhibit the
type of relations which hold between the entities which we in fact
perceive as in nature. We are not called on to make any pronouncement as
to the psychological relation of subjects to objects or as to the status
of either in the realm of reality. It is true that the issue of our
endeavour may provide material which is relevant evidence for a
discussion on that question. It can hardly fail to do so. But it is only
evidence, and is not itself the metaphysical discussion. In order to
make clear the character of this further discussion which is out of our
ken, I will set before you two quotations. One is from Schelling and I
extract the quotation from the work of the Russian philosopher Lossky
which has recently been so excellently translated into English<SPAN name="FNanchor_4_4" id="FNanchor_4_4"></SPAN><SPAN href="#Footnote_4_4" class="fnanchor">[4]</SPAN>—‘In
the “Philosophy of Nature” I considered the subject-object called nature
in its activity of self-constructing. In order to understand it, we must
rise to an intellectual intuition of nature. The empiricist does not
rise thereto, and for this reason in all his explanations it is always
<i>he himself</i> that proves to be constructing nature. It is no wonder,
then, that his construction and that which was to be constructed so
seldom coincide. A <i>Natur-philosoph</i> raises nature to independence, and
makes it construct itself, and he never feels, therefore, the necessity
of opposing nature<span class="pagenum" title="Page 48"> </span><SPAN name="Page_48" id="Page_48"></SPAN> as constructed (<i>i.e.</i> as experience) to real
nature, or of correcting the one by means of the other.’</p>
<div class="footnote"><p><SPAN name="Footnote_4_4" id="Footnote_4_4"></SPAN><span class="label"><SPAN href="#FNanchor_4_4">[4]</SPAN></span> <i>The Intuitive Basis of Knowledge</i>, by N. O. Lossky,
transl. by Mrs Duddington, Macmillan and Co., 1919.</p>
</div>
<p>The other quotation is from a paper read by the Dean of St Paul’s before
the Aristotelian Society in May of 1919. Dr Inge’s paper is entitled
‘Platonism and Human Immortality,’ and in it there occurs the following
statement: ‘To sum up. The Platonic doctrine of immortality rests on the
<i>independence</i> of the spiritual world. The spiritual world is not a
world of unrealised ideals, over against a real world of unspiritual
fact. It is, on the contrary, the real world, of which we have a true
though very incomplete knowledge, over against a world of common
experience which, as a complete whole, is not real, since it is
compacted out of miscellaneous data, not all on the same level, by the
help of the imagination. There is no world corresponding to the world of
our common experience. Nature makes abstractions for us, deciding what
range of vibrations we are to see and hear, what things we are to notice
and remember.’</p>
<p>I have cited these statements because both of them deal with topics
which, though they lie outside the range of our discussion, are always
being confused with it. The reason is that they lie proximate to our
field of thought, and are topics which are of burning interest to the
metaphysically minded. It is difficult for a philosopher to realise that
anyone really is confining his discussion within the limits that I have
set before you. The boundary is set up just where he is beginning to get
excited. But I submit to you that among the necessary prolegomena for
philosophy and for natural science is a thorough understanding of the
types of entities, and types of relations among those entities, which
are disclosed to us in our perceptions of nature.</p>
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