The Concept of Nature (Tarner Lectures, 1920) — Alfred North Whitehead

Ii] Theories of Bifurcation of Nature 29

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.

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 inco-
herence. 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 phenom,enon. It is for natural
philosophy to analyse how these various elements of
nature are connected.

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.

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

THE CONCEPT OF NATURE [ch.

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
inter se 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.

What I am essentially protesting against is the bi-
furcation of nature into two systems of reality, which,
in so far as they are real, are real in different senses.
One reahty 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.

Another way of phrasing this theory which I am arguing against is to bifurcate nature into two divisions,

Ii] Theories of Bifurcation of Nature 31

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.

There are four questions which at once suggest
themselves for discussion in connexion with this bi-
furcation 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.

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.

The bifurcation theory is an attempt to exhibit

32 THE CONCEPT OF NATURE [CH.

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.

However, we must admit that the causality theory of
nature has its strong suit. The reason why the bifurca-
tion 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 re-
spectively the cause and the mind's reaction to the cause.

Ii] Theories of Bifurcation of Nature 33

Time and space would appear to provide these all- embracing relations which the advocates of the philo- sophy 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.

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 charac- ter 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.

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.

34 THE CONCEPT OF NATURE [ch.

This is the absolute theory of time. Frankly, I con- fess 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 charac- teristic 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.

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.

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 ap-
parently have deeper roots in reality than has nature.
For we can imagine thoughts related in time without

Ii] Theories of Bifurcation of Nature 35

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 un- likeliness 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.

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.

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-

36 THE CONCEPT OF NATURE [ch.

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^ 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 subse-
quent 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.

This theory lacks the two main supports of the corre-
sponding 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