MAN AND HIS ENVIRONMENT
If our scientific knowledge were full and complete, we should
understand ourselves and the world and our relation to the world. As
it is, our understanding of all three is fragmentary. For the present,
it is the third question, that of our relation to the world, that I
wish to consider, because this brings us nearest to the problems of
philosophy. We shall find that it will lead us back to the other two
questions, as to the world and as to ourselves, but that we shall
understand both these better if we have considered first how the world
acts upon us and how we act upon the world.
There are a number of sciences which deal with Man. We may deal with
him in natural history, as one among the animals, having a certain
place in evolution, and related to other animals in ascertainable
ways. We may deal with him in physiology, as a structure capable of
performing certain functions, and reacting to the environment in ways
of which some, at least, can be explained by chemistry. We may study
him in sociology, as a unit in various organisms, such as the family
and the state. And we may study him, in psychology, as he appears to
himself. This last gives what we may call an internal view of man, as
opposed to the other three, which give an external view. That is to
say, in psychology we use data which can only be obtained when the
observer and the observed are the same person, whereas in the other
ways of studying Man all our data can be obtained by observing other
people. There are different ways of interpreting this distinction,
and different views of its importance, but there can be no doubt
that there is such a distinction. We can remember our own dreams,
whereas we cannot know the dreams of others unless they tell us about
them. We know when we have toothache, when our food tastes too salty,
when we are remembering some past occurrence, and so on. All these
events in our lives other people cannot know in the same direct way.
In this sense, we all have an inner life, open to our own inspection
but to no one else’s. This is no doubt the source of the traditional
distinction of mind and body: the body was supposed to be that part of
us which others could observe, and the mind that part which was private
to ourselves. The importance of the distinction has been called in
question in recent times, and I do not myself believe that it has any
fundamental philosophical significance. But historically it has played
a dominant part in determining the conceptions from which men set out
when they began to philosophise, and on this account, if on no other,
it deserves to be borne in mind.
Knowledge, traditionally, has been viewed from within, as something
which we observe in ourselves rather than as something which we can see
others displaying. When I say that it has been so viewed, I mean that
this has been the practice of philosophers; in ordinary life, people
have been more objective. In ordinary life, knowledge is something
which can be tested by examinations, that is to say, it consists in a
certain kind of response to a certain kind of stimulus. This objective
way of viewing knowledge is, to my mind, much more fruitful than the
way which has been customary in philosophy. I mean that, if we wish
to give a definition of “knowing”, we ought to define it as a manner
of reacting to the environment, not as involving something (a “state
of mind”) which only the person who has the knowledge can observe.
It is because I hold this view that I think it best to begin with
Man and his environment, rather than with those matters in which the
observer and the observed must be the same person. Knowing, as I view
it, is a characteristic which may be displayed in our reactions to our
environment; it is therefore necessary first of all to consider the
nature of these reactions as they appear in science.
Let us take some everyday situation. Suppose you are watching a race,
and at the appropriate moment you say, “they’re off”. This exclamation
is a reaction to the environment, and is taken to show knowledge if it
is made at the same time as others make it. Now let us consider what
has been really happening, according to science. The complication of
what has happened is almost incredible. It may conveniently be divided
into four stages: first, what happened in the outside world between the
runners and your eyes; secondly, what happened in your body from your
eyes to your brain; thirdly, what happened in your brain; fourthly,
what happened in your body from your brain to the movements of your
throat and tongue which constituted your exclamation. Of these four
stages, the first belongs to physics, and is dealt with in the main
by the theory of light; the second and fourth belong to physiology;
the third, though it should theoretically also belong to physiology,
belongs in fact rather to psychology, owing to our lack of knowledge
as to the brain. The third stage embodies the results of experience
and learning. It is responsible for the fact that you speak, which an
animal would not do, and that you speak English, which a Frenchman
would not do. This immensely complicated occurrence is, nevertheless,
about the simplest example of knowledge that could possibly be given.
For the moment, let us leave on one side the part of this process which
happens in the outside world and belongs to physics. I shall have much
to say about it later, but what has to be said is not altogether easy,
and we will take less abstruse matters first. I will merely observe
that the event which we are said to perceive, namely the runners
starting, is separated by a longer or shorter chain of events from the
event which happens at the surface of our eyes. It is this last that
is what is called the “stimulus”. Thus the event that we are said to
perceive when we see is not the stimulus, but an anterior event related
to it in a way that requires investigation. The same applies to hearing
and smell, but not to touch or to perception of states of our own
body. In these cases, the first of the above four stages is absent.
It is clear that, in the case of sight, hearing and smell, there must
be a certain relation between the stimulus and the event said to be
perceived, but we will not now consider what this relation must be. We
will consider, rather, the second, third, and fourth stages in an act
of perceptive knowledge. This is the more legitimate as these stages
always exist, whereas the first is confined to certain senses.
The second stage is that which proceeds from the sense-organ to the
brain. It is not necessary for our purposes to consider exactly
what goes on during this journey. A purely physical event--the
stimulus--happens at the boundary of the body, and has a series
of effects which travel along the afferent nerves to the brain.
If the stimulus is light, it must fall on the eye to produce the
characteristic effects; no doubt light falling on other parts of the
body has effects, but they are not those that distinguish vision.
Similarly, if the stimulus is sound, it must fall on the ear. A
sense-organ, like a photographic plate, is responsive to stimuli
of a certain sort: light falling on the eye has effects which are
different for different wave-lengths, intensities, and directions. When
the events in the eye due to incident light have taken place, they
are followed by events in the optic nerve, leading at last to some
occurrence in the brain--an occurrence which varies with the stimulus.
The occurrence in the brain must be different for different stimuli
in all cases where we can _perceive_ differences. Red and yellow, for
instance, are distinguishable in perception; therefore the occurrences
along the optic nerve and in the brain must have a different character
when caused by red light from what they have when caused by yellow
light. But when two shades of colour are so similar that they can only
be distinguished by delicate instruments, not by perception, we cannot
be sure that they cause occurrences of different characters in the
optic nerve and brain.
When the disturbance has reached the brain, it may or may not cause a
characteristic set of events in the brain. If it does not, we shall
not be what is called “conscious” of it. For to be “conscious” of
seeing yellow, whatever else it may be, must certainly involve some
kind of cerebral reaction to the message brought by the optic nerve.
It may be assumed that the great majority of messages brought to the
brain by the afferent nerves never secure any attention at all--they
are like letters to a government office which remain unanswered. The
things in the margin of the field of vision, unless they are in some
way interesting, are usually unnoticed; if they are noticed, they
are brought into the centre of the field of vision unless we make a
deliberate effort to prevent this from occurring. These things are
visible, in the sense that we could be aware of them if we chose,
without any change in our physical environment or in our sense-organs;
that is to say, only a cerebral change is required to enable them to
cause a reaction. But usually they do not provoke any reaction; life
would be altogether too wearing if we had to be always reacting to
everything in the field of vision. Where there is no reaction, the
second stage completes the process, and the third and fourth stages do
not arise. In that case, there has been nothing that could be called
“perception” connected with the stimulus in question.
To us, however, the interesting case is that in which the process
continues. In this case there is first a process in the brain, of
which the nature is as yet conjectural, which travels from the centre
appropriate to the sense in question to a motor centre. From these
there is a process which travels along an efferent nerve, and finally
results in a muscular event causing some bodily movement. In our
illustration of the man watching the beginning of a race, a process
travels from the part of the brain concerned with sight to the part
concerned with speech; this is what we called the third stage. Then
a process travels along the efferent nerves and brings about the
movements which constitute saying “they’re off”; this is what we called
the fourth stage.
Unless all four stages exist, there is nothing that can be called
“knowledge”. And even when they are all present, various further
conditions must be satisfied if there is to be “knowledge”. But these
observations are premature, and we must return to the analysis of our
third and fourth stages.
The third stage is of two sorts, according as we are concerned with
a reflex or with a “learned reaction”, as Dr. Watson calls it. In
the case of a reflex, if it is complete at birth, a new-born infant
or animal has a brain so constituted that, without the need of any
previous experience, there is a connection between a certain process in
the afferent nerves and a certain other process in the efferent nerves.
A good example of a reflex is sneezing. A certain kind of tickling in
the nose produces a fairly violent movement having a very definite
character, and this connection exists already in the youngest infants.
Learned reactions, on the other hand, are such as only occur because of
the effect of previous occurrences in the brain. One might illustrate
by an analogy which, however, would be misleading if pressed. Imagine
a desert in which no rain has ever fallen, and suppose that at last
a thunderstorm occurs in it; then the course taken by the water will
correspond to a reflex. But if rain continues to fall frequently, it
will form watercourses and river valleys; when this has occurred, the
water runs away along pre-formed channels, which are attributable to
the past “experience” of the region. This corresponds to “learned
reactions”. One of the most notable examples of learned reactions
is speech: we speak because we have learned a certain language, not
because our brain had originally any tendency to react in just that
way. Perhaps all knowledge, certainly nearly all, is dependent upon
learned reactions, _i.e._, upon connections in the brain which are not
part of man’s congenital equipment but are the result of events which
have happened to him.
To distinguish between learned and unlearned responses is not always an
easy task. It cannot be assumed that responses which are absent during
the first weeks of life are all learned. To take the most obvious
instance; sexual responses change their character to a greater or less
extent at puberty, as a result of changes in the ductless glands, not
as a result of experience. But this instance does not stand alone:
as the body grows and develops, new modes of response come into play,
modified, no doubt, by experience, but not wholly due to it. For
example: a new-born baby cannot run, and therefore does not run away
from what is terrifying, as an older child does. The older child has
learned to run, but has not necessarily learned to run _away_; the
stimulus in learning to run may have never been a terrifying object. It
would therefore be a fallacy to suppose that we can distinguish between
learned and unlearned responses by observing what a new-born infant
does, since reflexes may come into play at a later stage. Conversely,
some things which a child does at birth may have been learned, when
they are such as it could have done in the womb--for example, a certain
amount of kicking and stretching. The whole distinction between learned
and unlearned responses, therefore, is not so definite as we could
wish. At the two extremes we get clear cases, such as sneezing on the
one hand and speaking on the other; but there are intermediate forms of
behaviour which are more difficult to classify.
This is not denied even by those who attach most importance to the
distinction between learned and unlearned responses. In Dr. Watson’s
_Behaviorism_ (p. 103) there is a “Summary of Unlearned Equipment”,
which ends with the following paragraph:
“Other activities appear at a later stage--such as blinking, reaching,
handling, handedness, crawling, standing, sitting-up, walking, running,
jumping. _In the great majority of these later activities it is
difficult to say how much of the act as a whole is due to training
or conditioning. A considerable part is unquestionably due to the
growth changes in structure, and the remainder is due to training and
conditioning._” (Watson’s italics.)
It is not possible to make a logically sharp distinction in this
matter; in certain cases we have to be satisfied with something less
exact. For example, we might say that those developments which are
merely due to normal growth are to count as unlearned, while those
which depend upon special circumstances in the individual biography are
to count as learned. But take, say, muscular development: this will
not take place normally unless the muscles are used, and if they are
used they are bound to learn some of the skill which is appropriate to
them. And some things which must certainly count as learned, such as
focussing with the eyes, depend upon circumstances which are normal
and must be present in the case of every child who is not blind. The
whole distinction, therefore, is one of degree rather than of kind;
nevertheless it is valuable.
The value of the distinction between learned and unlearned reactions
is connected with the laws of learning, to which we shall come in the
next chapter. Experience modifies behaviour according to certain laws,
and we may say that a learned reaction is one in the formation of which
these laws have played a part. For example: children are frightened of
loud noises from birth, but are not at first frightened of dogs; after
they have heard a dog barking loudly, they may become frightened of
dogs, which is a learned reaction. If we knew enough about the brain,
we could make the distinction precise, by saying that learned reactions
are those depending upon modifications of the brain other than mere
growth. But as it is, we have to judge by observations of bodily
behaviour, and the accompanying modifications in the brain are assumed
on a basis of theory rather than actually observed.
The essential points, for our purposes, are comparatively simple.
Man or any other animal, at birth, is such as to respond to certain
stimuli in certain specific ways, _i.e._ by certain kinds of bodily
movements; as he grows, these ways of responding change, partly as the
mere result of developing structure, partly in consequence of events in
his biography. The latter influence proceeds according to certain laws,
which we shall consider, since they have much to do with the genesis of
“knowledge”.
But--the indignant reader may be exclaiming--knowing something is not
a bodily movement, but a state of mind, and yet you talk to us about
sneezing and such matters. I must ask the indignant reader’s patience.
He “knows” that he has states of mind, and that his knowing is itself
a state of mind. I do not deny that he has states of mind, but I ask
two questions: First, what sort of thing are they? Secondly, what
evidence can he give me that he knows about them? The first question
he may find very difficult; and if he wants, in his answer, to show
that states of mind are something of a sort totally different from
bodily movements, he will have to tell me also what bodily movements
are, which will plunge him into the most abstruse part of physics. All
this I propose to consider later on, and then I hope the indignant
reader will be appeased. As to the second question, namely, what
evidence of his knowledge another man can give me, it is clear that he
must depend upon speech or writing, _i.e._ in either case upon bodily
movements. Therefore whatever knowledge may be to the knower, as a
social phenomenon it is something displayed in bodily movements. For
the present I am deliberately postponing the question of what knowledge
is to the knower, and confining myself to what it is for the external
observer. And for him, necessarily, it is something shown by bodily
movements made in answer to stimuli--more specifically, to examination
questions. What else it may be I shall consider at a later stage.
However we may subsequently add to our present account by considering
how knowledge appears to the knower, that will not invalidate anything
that we may arrive at by considering how knowledge appears to the
external observer. And there is something which it is important
to realise, namely, that we are concerned with a process in which
the environment first acts upon a man, and then he reacts upon the
environment. This process has to be considered as a whole if we are
to discuss what knowledge is. The older view would have been that the
effect of the environment upon us might constitute a certain kind
of knowledge (perception), while our reaction to the environment
constituted volition. These were, in each case, “mental” occurrences,
and their connection with nerves and brain remained entirely
mysterious. I think the mystery can be eliminated, and the subject
removed from the realm of guesswork, by starting with the whole
cycle from stimulus to bodily movement. In this way, knowing becomes
something active, not something contemplative. Knowing and willing, in
fact, are merely aspects of the one cycle, which must be considered in
its entirety if it is to be rightly understood.
A few words must be said about the human body as a mechanism. It is
an inconceivably complicated mechanism, and some men of science think
that it is not explicable in terms of physics and chemistry, but is
regulated by some “vital principle” which makes its laws different
from those of dead matter. These men are called “vitalists”. I do not
myself see any reason to accept their view, but at the same time our
knowledge is not sufficient to enable us to reject it definitely. What
we can say is that their case is not proved, and that the opposite view
is, scientifically, a more fruitful working hypothesis. It is better
to look for physical and chemical explanations where we can, since
we know of many processes in the human body which can be accounted
for in this way, and of none which _certainly_ cannot. To invoke a
“vital principle” is to give an excuse for laziness, when perhaps more
diligent research would have enabled us to do without it. I shall
therefore assume, as a working hypothesis, that the human body acts
according to the same laws of physics and chemistry as those which
govern dead matter, and that it differs from dead matter, not by its
laws, but by the extraordinary complexity of its structure.
The movements of the human body may, none the less, be divided into two
classes, which we may call respectively “mechanical” and “vital”. As
an example of the former, I should give the movement of a man falling
from a cliff into the sea. To explain this, in its broad features, it
is not necessary to take account of the fact that the man is alive; his
centre of gravity moves exactly as that of a stone would move. But when
a man climbs up a cliff, he does something that dead matter of the
same shape and weight would never do; this is a “vital” movement. There
is in the human body a lot of stored chemical energy in more or less
unstable equilibrium; a very small stimulus can release this energy,
and cause a considerable amount of bodily movement. The situation is
analogous to that of a large rock delicately balanced on the top of a
conical mountain; a tiny shove may send it thundering down into the
valley, in one direction or another according to the direction of the
shove. So if you say to a man “your house is on fire”, he will start
running; although the stimulus contained very little energy, his
expenditure of energy may be tremendous. He increases the available
energy by panting, which makes his body burn up faster and increases
the energy due to combustion; this is just like opening the draft in a
furnace. “Vital” movements are those that use up this energy which is
in unstable equilibrium. It is they alone that concern the bio-chemist,
the physiologist, and the psychologist. The others, being just like
the movements of dead matter, may be ignored when we are specially
concerned with the study of Man.
Vital movements have a stimulus which may be inside or outside the
body, or both at once. Hunger is a stimulus inside the body, but
hunger combined with the sight of good food is a double stimulus, both
internal and external. The effect of a stimulus may be, in theory,
according to the laws of physics and chemistry, but in most cases
this is, at present, no more than a pious opinion. What we know from
observation is that behaviour is modified by experience, that is to
say, that if similar stimuli are repeated at intervals they produce
gradually changing reactions. When a bus conductor says, “Fares,
please”, a very young child has no reaction, an older child gradually
learns to look for pennies, and, if a male, ultimately acquires the
power of producing the requisite sum on demand without conscious
effort. The way in which our reactions change with experience is a
distinctive characteristic of animals; moreover it is more marked in
the higher than in the lower animals, and most marked of all in Man.
It is a matter intimately connected with “intelligence”, and must be
investigated before we can understand what constitutes knowledge from
the standpoint of the external observer; we shall be concerned with it
at length in the next chapter.
Speaking broadly, the actions of all living things are such as tend to
biological survival, _i.e._ to the leaving of a numerous progeny. But
when we descend to the lowest organisms, which have hardly anything
that can be called individuality, and reproduce themselves by fission,
it is possible to take a simpler view. Living matter, within limits,
has the chemical peculiarity of being self-perpetuating, and of
conferring its own chemical composition upon other matter composed of
the right elements. One spore falling into a stagnant pond may produce
millions of minute vegetable organisms; these, in turn, enable one
small animal to have myriads of descendants living on the small plants;
these, in turn, provide life for larger animals, newts, tadpoles,
fishes, etc. In the end there is enormously more protoplasm in that
region than there was to begin with. This is no doubt explicable as a
result of the chemical constitution of living matter. But this purely
chemical self-preservation and collective growth is at the bottom of
everything else that characterises the behaviour of living things.
Every living thing is a sort of imperialist, seeking to transform as
much as possible of its environment into itself and its seed. The
distinction between self and posterity is one which does not exist in
a developed form in asexual unicellular organisms; many things, even
in human life, can only be completely understood by forgetting it.
We may regard the whole of evolution as flowing from this “chemical
imperialism” of living matter. Of this, Man is only the last example
(so far). He transforms the surface of the globe by irrigation,
cultivation, mining, quarrying, making canals and railways, breeding
certain animals, and destroying others; and when we ask ourselves,
from the standpoint of an outside observer, what is the end achieved
by all these activities, we find that it can be summed up in one
very simple formula: to transform as much as possible of the matter
on the earth’s surface into human bodies. Domestication of animals,
agriculture, commerce, industrialism have been stages in this process.
When we compare the human population of the globe with that of
other large animals and also with that of former times, we see that
“chemical imperialism” has been, in fact, the main end to which human
intelligence has been devoted. Perhaps intelligence is reaching the
point where it can conceive worthier ends, concerned with the quality
rather than the quantity of human life. But as yet such intelligence
is confined to minorities, and does not control the great movements of
human affairs. Whether this will ever be changed I do not venture to
predict. And in pursuing the simple purpose of maximising the amount of
human life, we have at any rate the consolation of feeling at one with
the whole movement of living things from their earliest origin on this
planet.