Desire is a subject upon which, if I am not mistaken, true views can
only be arrived at by an almost complete reversal of the ordinary
unreflecting opinion. It is natural to regard desire as in its essence
an attitude towards something which is imagined, not actual; this
something is called the END or OBJECT of the desire, and is said to be
the PURPOSE of any action resulting from the desire. We think of the
content of the desire as being just like the content of a belief, while
the attitude taken up towards the content is different. According to
this theory, when we say: "I hope it will rain," or "I expect it will
rain," we express, in the first case, a desire, and in the second, a
belief, with an identical content, namely, the image of rain. It would
be easy to say that, just as belief is one kind of feeling in relation
to this content, so desire is another kind. According to this view, what
comes first in desire is something imagined, with a specific feeling
related to it, namely, that specific feeling which we call "desiring"
it. The discomfort associated with unsatisfied desire, and the actions
which aim at satisfying desire, are, in this view, both of them effects
of the desire. I think it is fair to say that this is a view against
which common sense would not rebel; nevertheless, I believe it to be
radically mistaken. It cannot be refuted logically, but various facts
can be adduced which make it gradually less simple and plausible, until
at last it turns out to be easier to abandon it wholly and look at the
matter in a totally different way.
The first set of facts to be adduced against the common sense view of
desire are those studied by psycho-analysis. In all human beings, but
most markedly in those suffering from hysteria and certain forms of
insanity, we find what are called "unconscious" desires, which are
commonly regarded as showing self-deception. Most psycho-analysts
pay little attention to the analysis of desire, being interested in
discovering by observation what it is that people desire, rather than in
discovering what actually constitutes desire. I think the strangeness of
what they report would be greatly diminished if it were expressed in the
language of a behaviourist theory of desire, rather than in the language
of every-day beliefs. The general description of the sort of phenomena
that bear on our present question is as follows: A person states that
his desires are so-and-so, and that it is these desires that inspire his
actions; but the outside observer perceives that his actions are such
as to realize quite different ends from those which he avows, and
that these different ends are such as he might be expected to desire.
Generally they are less virtuous than his professed desires, and are
therefore less agreeable to profess than these are. It is accordingly
supposed that they really exist as desires for ends, but in a
subconscious part of the mind, which the patient refuses to admit into
consciousness for fear of having to think ill of himself. There are
no doubt many cases to which such a supposition is applicable without
obvious artificiality. But the deeper the Freudians delve into the
underground regions of instinct, the further they travel from anything
resembling conscious desire, and the less possible it becomes to believe
that only positive self-deception conceals from us that we really wish
for things which are abhorrent to our explicit life.
In the cases in question we have a conflict between the outside observer
and the patient's consciousness. The whole tendency of psycho-analysis
is to trust the outside observer rather than the testimony of
introspection. I believe this tendency to be entirely right, but to
demand a re-statement of what constitutes desire, exhibiting it as a
causal law of our actions, not as something actually existing in our
minds.
But let us first get a clearer statement of the essential characteristic
of the phenomena.
A person, we find, states that he desires a certain end A, and that he
is acting with a view to achieving it. We observe, however, that his
actions are such as are likely to achieve a quite different end B, and
that B is the sort of end that often seems to be aimed at by animals and
savages, though civilized people are supposed to have discarded it. We
sometimes find also a whole set of false beliefs, of such a kind as to
persuade the patient that his actions are really a means to A, when in
fact they are a means to B. For example, we have an impulse to inflict
pain upon those whom we hate; we therefore believe that they are wicked,
and that punishment will reform them. This belief enables us to act upon
the impulse to inflict pain, while believing that we are acting upon
the desire to lead sinners to repentance. It is for this reason that the
criminal law has been in all ages more severe than it would have been if
the impulse to ameliorate the criminal had been what really inspired
it. It seems simple to explain such a state of affairs as due to
"self-deception," but this explanation is often mythical. Most people,
in thinking about punishment, have had no more need to hide their
vindictive impulses from themselves than they have had to hide
the exponential theorem. Our impulses are not patent to a casual
observation, but are only to be discovered by a scientific study of our
actions, in the course of which we must regard ourselves as objectively
as we should the motions of the planets or the chemical reactions of a
new element.
The study of animals reinforces this conclusion, and is in many ways
the best preparation for the analysis of desire. In animals we are
not troubled by the disturbing influence of ethical considerations. In
dealing with human beings, we are perpetually distracted by being told
that such-and-such a view is gloomy or cynical or pessimistic: ages of
human conceit have built up such a vast myth as to our wisdom and virtue
that any intrusion of the mere scientific desire to know the facts is
instantly resented by those who cling to comfortable illusions. But no
one cares whether animals are virtuous or not, and no one is under the
delusion that they are rational. Moreover, we do not expect them to be
so "conscious," and are prepared to admit that their instincts prompt
useful actions without any prevision of the ends which they achieve. For
all these reasons, there is much in the analysis of mind which is more
easily discovered by the study of animals than by the observation of
human beings.
We all think that, by watching the behaviour of animals, we can discover
more or less what they desire. If this is the case--and I fully agree
that it is--desire must be capable of being exhibited in actions, for it
is only the actions of animals that we can observe. They MAY have minds
in which all sorts of things take place, but we can know nothing about
their minds except by means of inferences from their actions; and the
more such inferences are examined, the more dubious they appear. It
would seem, therefore, that actions alone must be the test of the
desires of animals. From this it is an easy step to the conclusion that
an animal's desire is nothing but a characteristic of a certain series
of actions, namely, those which would be commonly regarded as inspired
by the desire in question. And when it has been shown that this view
affords a satisfactory account of animal desires, it is not difficult
to see that the same explanation is applicable to the desires of human
beings.
We judge easily from the behaviour of an animal of a familiar
kind whether it is hungry or thirsty, or pleased or displeased, or
inquisitive or terrified. The verification of our judgment, so far
as verification is possible, must be derived from the immediately
succeeding actions of the animal. Most people would say that they infer
first something about the animal's state of mind--whether it is hungry
or thirsty and so on--and thence derive their expectations as to its
subsequent conduct. But this detour through the animal's supposed mind
is wholly unnecessary. We can say simply: The animal's behaviour during
the last minute has had those characteristics which distinguish what
is called "hunger," and it is likely that its actions during the next
minute will be similar in this respect, unless it finds food, or is
interrupted by a stronger impulse, such as fear. An animal which is
hungry is restless, it goes to the places where food is often to be
found, it sniffs with its nose or peers with its eyes or otherwise
increases the sensitiveness of its sense-organs; as soon as it is near
enough to food for its sense-organs to be affected, it goes to it with
all speed and proceeds to eat; after which, if the quantity of food has
been sufficient, its whole demeanour changes it may very likely lie
down and go to sleep. These things and others like them are observable
phenomena distinguishing a hungry animal from one which is not hungry.
The characteristic mark by which we recognize a series of actions
which display hunger is not the animal's mental state, which we cannot
observe, but something in its bodily behaviour; it is this observable
trait in the bodily behaviour that I am proposing to call "hunger,"
not some possibly mythical and certainly unknowable ingredient of the
animal's mind.
Generalizing what occurs in the case of hunger, we may say that what
we call a desire in an animal is always displayed in a cycle of actions
having certain fairly well marked characteristics. There is first a
state of activity, consisting, with qualifications to be mentioned
presently, of movements likely to have a certain result; these
movements, unless interrupted, continue until the result is achieved,
after which there is usually a period of comparative quiescence. A cycle
of actions of this sort has marks by which it is broadly distinguished
from the motions of dead matter. The most notable of these marks
are--(1) the appropriateness of the actions for the realization of a
certain result; (2) the continuance of action until that result has been
achieved. Neither of these can be pressed beyond a point. Either may
be (a) to some extent present in dead matter, and (b) to a considerable
extent absent in animals, while vegetable are intermediate, and display
only a much fainter form of the behaviour which leads us to attribute
desire to animals. (a) One might say rivers "desire" the sea water,
roughly speaking, remains in restless motion until it reaches either
the sea or a place from which it cannot issue without going uphill, and
therefore we might say that this is what it wishes while it is flowing.
We do not say so, because we can account for the behaviour of water by
the laws of physics; and if we knew more about animals, we might equally
cease to attribute desires to them, since we might find physical and
chemical reactions sufficient to account for their behaviour. (b) Many
of the movements of animals do not exhibit the characteristics of the
cycles which seem to embody desire. There are first of all the movements
which are "mechanical," such as slipping and falling, where ordinary
physical forces operate upon the animal's body almost as if it were
dead matter. An animal which falls over a cliff may make a number of
desperate struggles while it is in the air, but its centre of gravity
will move exactly as it would if the animal were dead. In this case, if
the animal is killed at the end of the fall, we have, at first sight,
just the characteristics of a cycle of actions embodying desire, namely,
restless movement until the ground is reached, and then quiescence.
Nevertheless, we feel no temptation to say that the animal desired what
occurred, partly because of the obviously mechanical nature of the whole
occurrence, partly because, when an animal survives a fall, it tends not
to repeat the experience.
There may be other reasons also, but of them I do not wish to speak yet.
Besides mechanical movements, there are interrupted movements, as when
a bird, on its way to eat your best peas, is frightened away by the boy
whom you are employing for that purpose. If interruptions are frequent
and completion of cycles rare, the characteristics by which cycles
are observed may become so blurred as to be almost unrecognizable. The
result of these various considerations is that the differences
between animals and dead matter, when we confine ourselves to external
unscientific observation of integral behaviour, are a matter of degree
and not very precise. It is for this reason that it has always been
possible for fanciful people to maintain that even stocks and stones
have some vague kind of soul. The evidence that animals have souls is
so very shaky that, if it is assumed to be conclusive, one might just as
well go a step further and extend the argument by analogy to all matter.
Nevertheless, in spite of vagueness and doubtful cases, the existence
of cycles in the behaviour of animals is a broad characteristic by which
they are prima facie distinguished from ordinary matter; and I think it
is this characteristic which leads us to attribute desires to animals,
since it makes their behaviour resemble what we do when (as we say) we
are acting from desire.
I shall adopt the following definitions for describing the behaviour of
animals:
A "behaviour-cycle" is a series of voluntary or reflex movements of an
animal, tending to cause a certain result, and continuing until that
result is caused, unless they are interrupted by death, accident,
or some new behaviour-cycle. (Here "accident" may be defined as the
intervention of purely physical laws causing mechanical movements.)
The "purpose" of a behaviour-cycle is the result which brings it to an
end, normally by a condition of temporary quiescence-provided there is
no interruption.
An animal is said to "desire" the purpose of a behaviour cycle while the
behaviour-cycle is in progress.
I believe these definitions to be adequate also to human purposes and
desires, but for the present I am only occupied with animals and with
what can be learnt by external observation. I am very anxious that no
ideas should be attached to the words "purpose" and "desire" beyond
those involved in the above definitions.
We have not so far considered what is the nature of the initial stimulus
to a behaviour-cycle. Yet it is here that the usual view of desire seems
on the strongest ground. The hungry animal goes on making movements
until it gets food; it seems natural, therefore, to suppose that the
idea of food is present throughout the process, and that the thought of
the end to be achieved sets the whole process in motion. Such a view,
however, is obviously untenable in many cases, especially where instinct
is concerned. Take, for example, reproduction and the rearing of the
young. Birds mate, build a nest, lay eggs in it, sit on the eggs, feed
the young birds, and care for them until they are fully grown. It
is totally impossible to suppose that this series of actions, which
constitutes one behaviour-cycle, is inspired by any prevision of the
end, at any rate the first time it is performed.* We must suppose that
the stimulus to the performance of each act is an impulsion from behind,
not an attraction from the future. The bird does what it does, at each
stage, because it has an impulse to that particular action, not because
it perceives that the whole cycle of actions will contribute to the
preservation of the species. The same considerations apply to other
instincts. A hungry animal feels restless, and is led by instinctive
impulses to perform the movements which give it nourishment; but the act
of seeking food is not sufficient evidence from which to conclude that
the animal has the thought of food in its "mind."
* For evidence as to birds' nests, cf. Semon, "Die Mneme,"
pp. 209, 210.
Coming now to human beings, and to what we know about our own actions,
it seems clear that what, with us, sets a behaviour-cycle in motion is
some sensation of the sort which we call disagreeable. Take the case
of hunger: we have first an uncomfortable feeling inside, producing a
disinclination to sit still, a sensitiveness to savoury smells, and an
attraction towards any food that there may be in our neighbourhood. At
any moment during this process we may become aware that we are hungry,
in the sense of saying to ourselves, "I am hungry"; but we may have been
acting with reference to food for some time before this moment. While we
are talking or reading, we may eat in complete unconsciousness; but we
perform the actions of eating just as we should if we were conscious,
and they cease when our hunger is appeased. What we call "consciousness"
seems to be a mere spectator of the process; even when it issues orders,
they are usually, like those of a wise parent, just such as would have
been obeyed even if they had not been given. This view may seem at first
exaggerated, but the more our so-called volitions and their causes are
examined, the more it is forced upon us. The part played by words in all
this is complicated, and a potent source of confusions; I shall return
to it later. For the present, I am still concerned with primitive
desire, as it exists in man, but in the form in which man shows his
affinity to his animal ancestors.
Conscious desire is made up partly of what is essential to desire,
partly of beliefs as to what we want. It is important to be clear as to
the part which does not consist of beliefs.
The primitive non-cognitive element in desire seems to be a push, not
a pull, an impulsion away from the actual, rather than an attraction
towards the ideal. Certain sensations and other mental occurrences have
a property which we call discomfort; these cause such bodily movements
as are likely to lead to their cessation. When the discomfort ceases,
or even when it appreciably diminishes, we have sensations possessing a
property which we call PLEASURE. Pleasurable sensations either stimulate
no action at all, or at most stimulate such action as is likely to
prolong them. I shall return shortly to the consideration of what
discomfort and pleasure are in themselves; for the present, it is
their connection with action and desire that concerns us. Abandoning
momentarily the standpoint of behaviourism, we may presume that hungry
animals experience sensations involving discomfort, and stimulating such
movements as seem likely to bring them to the food which is outside the
cages. When they have reached the food and eaten it, their discomfort
ceases and their sensations become pleasurable. It SEEMS, mistakenly, as
if the animals had had this situation in mind throughout, when in fact
they have been continually pushed by discomfort. And when an animal
is reflective, like some men, it comes to think that it had the final
situation in mind throughout; sometimes it comes to know what situation
will bring satisfaction, so that in fact the discomfort does bring the
thought of what will allay it. Nevertheless the sensation involving
discomfort remains the prime mover.
This brings us to the question of the nature of discomfort and pleasure.
Since Kant it has been customary to recognize three great divisions of
mental phenomena, which are typified by knowledge, desire and feeling,
where "feeling" is used to mean pleasure and discomfort. Of course,
"knowledge" is too definite a word: the states of mind concerned are
grouped together as "cognitive," and are to embrace not only beliefs,
but perceptions, doubts, and the understanding of concepts. "Desire,"
also, is narrower than what is intended: for example, WILL is to be
included in this category, and in fact every thing that involves any
kind of striving, or "conation" as it is technically called. I do not
myself believe that there is any value in this threefold division of the
contents of mind. I believe that sensations (including images) supply
all the "stuff" of the mind, and that everything else can be analysed
into groups of sensations related in various ways, or characteristics of
sensations or of groups of sensations. As regards belief, I shall give
grounds for this view in later lectures. As regards desires, I have
given some grounds in this lecture. For the present, it is pleasure and
discomfort that concern us. There are broadly three theories that might
be held in regard to them. We may regard them as separate existing
items in those who experience them, or we may regard them as intrinsic
qualities of sensations and other mental occurrences, or we may regard
them as mere names for the causal characteristics of the occurrences
which are uncomfortable or pleasant. The first of these theories,
namely, that which regards discomfort and pleasure as actual contents in
those who experience them, has, I think, nothing conclusive to be said
in its favour.* It is suggested chiefly by an ambiguity in the word
"pain," which has misled many people, including Berkeley, whom it
supplied with one of his arguments for subjective idealism. We may use
"pain" as the opposite of "pleasure," and "painful" as the opposite of
"pleasant," or we may use "pain" to mean a certain sort of sensation, on
a level with the sensations of heat and cold and touch. The latter use
of the word has prevailed in psychological literature, and it is now
no longer used as the opposite of "pleasure." Dr. H. Head, in a recent
publication, has stated this distinction as follows:**
* Various arguments in its favour are advanced by A.
Wohlgemuth, "On the feelings and their neural correlate,
with an examination of the nature of pain," "British Journal
of Psychology," viii, 4. (1917). But as these arguments are
largely a reductio ad absurdum of other theories, among
which that which I am advocating is not included, I cannot
regard them as establishing their contention.
** "Sensation and the Cerebral Cortex," "Brain," vol. xli,
part ii (September, 1918), p. 90. Cf. also Wohlgemuth, loc.
cit. pp. 437, 450.
"It is necessary at the outset to distinguish clearly between
'discomfort' and 'pain.' Pain is a distinct sensory quality equivalent
to heat and cold, and its intensity can be roughly graded according to
the force expended in stimulation. Discomfort, on the other hand,
is that feeling-tone which is directly opposed to pleasure. It may
accompany sensations not in themselves essentially painful; as for
instance that produced by tickling the sole of the foot. The reaction
produced by repeated pricking contains both these elements; for it
evokes that sensory quality known as pain, accompanied by a disagreeable
feeling-tone, which we have called discomfort. On the other hand,
excessive pressure, except when applied directly over some nerve-trunk,
tends to excite more discomfort than pain."
The confusion between discomfort and pain has made people regard
discomfort as a more substantial thing than it is, and this in turn has
reacted upon the view taken of pleasure, since discomfort and pleasure
are evidently on a level in this respect. As soon as discomfort is
clearly distinguished from the sensation of pain, it becomes more
natural to regard discomfort and pleasure as properties of mental
occurrences than to regard them as separate mental occurrences on their
own account. I shall therefore dismiss the view that they are separate
mental occurrences, and regard them as properties of such experiences as
would be called respectively uncomfortable and pleasant.
It remains to be examined whether they are actual qualities of such
occurrences, or are merely differences as to causal properties. I do not
myself see any way of deciding this question; either view seems equally
capable of accounting for the facts. If this is true, it is safer to
avoid the assumption that there are such intrinsic qualities of
mental occurrences as are in question, and to assume only the causal
differences which are undeniable. Without condemning the intrinsic
theory, we can define discomfort and pleasure as consisting in causal
properties, and say only what will hold on either of the two theories.
Following this course, we shall say:
"Discomfort" is a property of a sensation or other mental occurrence,
consisting in the fact that the occurrence in question stimulates
voluntary or reflex movements tending to produce some more or less
definite change involving the cessation of the occurrence.
"Pleasure" is a property of a sensation or other mental occurrence,
consisting in the fact that the occurrence in question either does not
stimulate any voluntary or reflex movement, or, if it does, stimulates
only such as tend to prolong the occurrence in question.*
* Cf. Thorndike, op. cit., p. 243.
"Conscious" desire, which we have now to consider, consists of desire
in the sense hitherto discussed, together with a true belief as to its
"purpose," i.e. as to the state of affairs that will bring quiescence
with cessation of the discomfort. If our theory of desire is correct,
a belief as to its purpose may very well be erroneous, since only
experience can show what causes a discomfort to cease. When the
experience needed is common and simple, as in the case of hunger, a
mistake is not very probable. But in other cases--e.g. erotic desire in
those who have had little or no experience of its satisfaction--mistakes
are to be expected, and do in fact very often occur. The practice of
inhibiting impulses, which is to a great extent necessary to civilized
life, makes mistakes easier, by preventing experience of the actions to
which a desire would otherwise lead, and by often causing the inhibited
impulses themselves to be unnoticed or quickly forgotten. The perfectly
natural mistakes which thus arise constitute a large proportion of what
is, mistakenly in part, called self-deception, and attributed by Freud
to the "censor."
But there is a further point which needs emphasizing, namely, that a
belief that something is desired has often a tendency to cause the very
desire that is believed in. It is this fact that makes the effect of
"consciousness" on desire so complicated.
When we believe that we desire a certain state of affairs, that often
tends to cause a real desire for it. This is due partly to the influence
of words upon our emotions, in rhetoric for example, and partly to the
general fact that discomfort normally belongs to the belief that we
desire such-and-such a thing that we do not possess. Thus what was
originally a false opinion as to the object of a desire acquires a
certain truth: the false opinion generates a secondary subsidiary
desire, which nevertheless becomes real. Let us take an illustration.
Suppose you have been jilted in a way which wounds your vanity. Your
natural impulsive desire will be of the sort expressed in Donne's poem:
When by thy scorn, O Murderess, I am dead,
in which he explains how he will haunt the poor lady as a ghost, and
prevent her from enjoying a moment's peace. But two things stand in
the way of your expressing yourself so naturally: on the one hand, your
vanity, which will not acknowledge how hard you are hit; on the other
hand, your conviction that you are a civilized and humane person,
who could not possibly indulge so crude a desire as revenge. You will
therefore experience a restlessness which will at first seem quite
aimless, but will finally resolve itself in a conscious desire to change
your profession, or go round the world, or conceal your identity and
live in Putney, like Arnold Bennett's hero. Although the prime cause of
this desire is a false judgment as to your previous unconscious desire,
yet the new conscious desire has its own derivative genuineness, and may
influence your actions to the extent of sending you round the world.
The initial mistake, however, will have effects of two kinds. First,
in uncontrolled moments, under the influence of sleepiness or drink
or delirium, you will say things calculated to injure the faithless
deceiver. Secondly, you will find travel disappointing, and the East
less fascinating than you had hoped--unless, some day, you hear that the
wicked one has in turn been jilted. If this happens, you will believe
that you feel sincere sympathy, but you will suddenly be much more
delighted than before with the beauties of tropical islands or the
wonders of Chinese art. A secondary desire, derived from a false
judgment as to a primary desire, has its own power of influencing
action, and is therefore a real desire according to our definition.
But it has not the same power as a primary desire of bringing thorough
satisfaction when it is realized; so long as the primary desire remains
unsatisfied, restlessness continues in spite of the secondary desire's
success. Hence arises a belief in the vanity of human wishes: the vain
wishes are those that are secondary, but mistaken beliefs prevent us
from realizing that they are secondary.
What may, with some propriety, be called self-deception arises through
the operation of desires for beliefs. We desire many things which it is
not in our power to achieve: that we should be universally popular and
admired, that our work should be the wonder of the age, and that the
universe should be so ordered as to bring ultimate happiness to all,
though not to our enemies until they have repented and been purified
by suffering. Such desires are too large to be achieved through our own
efforts. But it is found that a considerable portion of the satisfaction
which these things would bring us if they were realized is to be
achieved by the much easier operation of believing that they are or
will be realized. This desire for beliefs, as opposed to desire for the
actual facts, is a particular case of secondary desire, and, like all
secondary desire its satisfaction does not lead to a complete cessation
of the initial discomfort. Nevertheless, desire for beliefs, as opposed
to desire for facts, is exceedingly potent both individually and
socially. According to the form of belief desired, it is called vanity,
optimism, or religion. Those who have sufficient power usually imprison
or put to death any one who tries to shake their faith in their own
excellence or in that of the universe; it is for this reason that
seditious libel and blasphemy have always been, and still are, criminal
offences.
It is very largely through desires for beliefs that the primitive
nature of desire has become so hidden, and that the part played by
consciousness has been so confusing and so exaggerated.
We may now summarize our analysis of desire and feeling.
A mental occurrence of any kind--sensation, image, belief, or
emotion--may be a cause of a series of actions, continuing, unless
interrupted, until some more or less definite state of affairs is
realized. Such a series of actions we call a "behaviour-cycle." The
degree of definiteness may vary greatly: hunger requires only food in
general, whereas the sight of a particular piece of food raises a desire
which requires the eating of that piece of food. The property of causing
such a cycle of occurrences is called "discomfort"; the property of the
mental occurrences in which the cycle ends is called "pleasure." The
actions constituting the cycle must not be purely mechanical, i.e. they
must be bodily movements in whose causation the special properties
of nervous tissue are involved. The cycle ends in a condition of
quiescence, or of such action as tends only to preserve the status quo.
The state of affairs in which this condition of quiescence is achieved
is called the "purpose" of the cycle, and the initial mental occurrence
involving discomfort is called a "desire" for the state of affairs that
brings quiescence. A desire is called "conscious" when it is accompanied
by a true belief as to the state of affairs that will bring quiescence;
otherwise it is called "unconscious." All primitive desire is
unconscious, and in human beings beliefs as to the purposes of desires
are often mistaken. These mistaken beliefs generate secondary desires,
which cause various interesting complications in the psychology of human
desire, without fundamentally altering the character which it shares
with animal desire.
LECTURE IV. INFLUENCE OF PAST HISTORY ON PRESENT OCCURRENCES IN LIVING
ORGANISMS
In this lecture we shall be concerned with a very general characteristic
which broadly, though not absolutely, distinguishes the behaviour
of living organisms from that of dead matter. The characteristic in
question is this:
The response of an organism to a given stimulus is very often dependent
upon the past history of the organism, and not merely upon the stimulus
and the HITHERTO DISCOVERABLE present state of the organism.
This characteristic is embodied in the saying "a burnt child fears the
fire." The burn may have left no visible traces, yet it modifies the
reaction of the child in the presence of fire. It is customary to assume
that, in such cases, the past operates by modifying the structure of the
brain, not directly. I have no wish to suggest that this hypothesis is
false; I wish only to point out that it is a hypothesis. At the end of
the present lecture I shall examine the grounds in its favour. If we
confine ourselves to facts which have been actually observed, we must
say that past occurrences, in addition to the present stimulus and
the present ascertainable condition of the organism, enter into the
causation of the response.
The characteristic is not wholly confined to living organisms. For
example, magnetized steel looks just like steel which has not been
magnetized, but its behaviour is in some ways different. In the case
of dead matter, however, such phenomena are less frequent and important
than in the case of living organisms, and it is far less difficult
to invent satisfactory hypotheses as to the microscopic changes of
structure which mediate between the past occurrence and the present
changed response. In the case of living organisms, practically
everything that is distinctive both of their physical and of their
mental behaviour is bound up with this persistent influence of the past.
Further, speaking broadly, the change in response is usually of a kind
that is biologically advantageous to the organism.
Following a suggestion derived from Semon ("Die Mneme," Leipzig, 1904;
2nd edition, 1908, English translation, Allen & Unwin, 1921; "Die
mnemischen Empfindungen," Leipzig, 1909), we will give the name of
"mnemic phenomena" to those responses of an organism which, so far as
hitherto observed facts are concerned, can only be brought under causal
laws by including past occurrences in the history of the organism as
part of the causes of the present response. I do not mean merely--what
would always be the case--that past occurrences are part of a CHAIN of
causes leading to the present event. I mean that, in attempting to state
the PROXIMATE cause of the present event, some past event or events
must be included, unless we take refuge in hypothetical modifications of
brain structure. For example: you smell peat-smoke, and you recall some
occasion when you smelt it before. The cause of your recollection, so
far as hitherto observable phenomena are concerned, consists both
of the peat smoke (present stimulus) and of the former occasion (past
experience). The same stimulus will not produce the same recollection
in another man who did not share your former experience, although the
former experience left no OBSERVABLE traces in the structure of the
brain. According to the maxim "same cause, same effect," we cannot
therefore regard the peat-smoke alone as the cause of your recollection,
since it does not have the same effect in other cases. The cause of
your recollection must be both the peat-smoke and the past occurrence.
Accordingly your recollection is an instance of what we are calling
"mnemic phenomena."
Before going further, it will be well to give illustrations of different
classes of mnemic phenomena.
(a) ACQUIRED HABITS.--In Lecture II we saw how animals can learn by
experience how to get out of cages or mazes, or perform other actions
which are useful to them but not provided for by their instincts alone.
A cat which is put into a cage of which it has had experience behaves
differently from the way in which it behaved at first. We can easily
invent hypotheses, which are quite likely to be true, as to connections
in the brain caused by past experience, and themselves causing the
different response. But the observable fact is that the stimulus of
being in the cage produces differing results with repetition, and that
the ascertainable cause of the cat's behaviour is not merely the cage
and its own ascertainable organization, but also its past history
in regard to the cage. From our present point of view, the matter is
independent of the question whether the cat's behaviour is due to some
mental fact called "knowledge," or displays a merely bodily habit. Our
habitual knowledge is not always in our minds, but is called up by the
appropriate stimuli. If we are asked "What is the capital of France?"
we answer "Paris," because of past experience; the past experience is as
essential as the present question in the causation of our response. Thus
all our habitual knowledge consists of acquired habits, and comes under
the head of mnemic phenomena.
(b) IMAGES.--I shall have much to say about images in a later lecture;
for the present I am merely concerned with them in so far as they are
"copies" of past sensations. When you hear New York spoken of, some
image probably comes into your mind, either of the place itself (if you
have been there), or of some picture of it (if you have not). The image
is due to your past experience, as well as to the present stimulus of
the words "New York." Similarly, the images you have in dreams are
all dependent upon your past experience, as well as upon the present
stimulus to dreaming. It is generally believed that all images, in their
simpler parts, are copies of sensations; if so, their mnemic character
is evident. This is important, not only on its own account, but also
because, as we shall see later, images play an essential part in what is
called "thinking."
(c) ASSOCIATION.--The broad fact of association, on the mental side, is
that when we experience something which we have experienced before,
it tends to call up the context of the former experience. The smell of
peat-smoke recalling a former scene is an instance which we discussed a
moment ago. This is obviously a mnemic phenomenon. There is also a more
purely physical association, which is indistinguishable from physical
habit. This is the kind studied by Mr. Thorndike in animals, where a
certain stimulus is associated with a certain act. This is the sort
which is taught to soldiers in drilling, for example. In such a case
there need not be anything mental, but merely a habit of the body.
There is no essential distinction between association and habit, and the
observations which we made concerning habit as a mnemic phenomenon are
equally applicable to association.
(d) NON-SENSATIONAL ELEMENTS IN PERCEPTION.--When we perceive any object
of a familiar kind, much of what appears subjectively to be immediately
given is really derived from past experience. When we see an object, say
a penny, we seem to be aware of its "real" shape we have the impression
of something circular, not of something elliptical. In learning to draw,
it is necessary to acquire the art of representing things according
to the sensation, not according to the perception. And the visual
appearance is filled out with feeling of what the object would be like
to touch, and so on. This filling out and supplying of the "real" shape
and so on consists of the most usual correlates of the sensational core
in our perception. It may happen that, in the particular case, the real
correlates are unusual; for example, if what we are seeing is a
carpet made to look like tiles. If so, the non-sensational part of our
perception will be illusory, i.e. it will supply qualities which the
object in question does not in fact have. But as a rule objects do
have the qualities added by perception, which is to be expected,
since experience of what is usual is the cause of the addition. If our
experience had been different, we should not fill out sensation in
the same way, except in so far as the filling out is instinctive,
not acquired. It would seem that, in man, all that makes up space
perception, including the correlation of sight and touch and so on, is
almost entirely acquired. In that case there is a large mnemic element
in all the common perceptions by means of which we handle common
objects. And, to take another kind of instance, imagine what our
astonishment would be if we were to hear a cat bark or a dog mew. This
emotion would be dependent upon past experience, and would therefore be
a mnemic phenomenon according to the definition.
(e) MEMORY AS KNOWLEDGE.--The kind of memory of which I am now speaking
is definite knowledge of some past event in one's own experience.
From time to time we remember things that have happened to us, because
something in the present reminds us of them. Exactly the same present
fact would not call up the same memory if our past experience had been
different. Thus our remembering is caused by--
(1) The present stimulus,
(2) The past occurrence.
It is therefore a mnemic phenomenon according to our definition. A
definition of "mnemic phenomena" which did not include memory would,
of course, be a bad one. The point of the definition is not that it
includes memory, but that it includes it as one of a class of phenomena
which embrace all that is characteristic in the subject matter of
psychology.
(f) EXPERIENCE.--The word "experience" is often used very vaguely.
James, as we saw, uses it to cover the whole primal stuff of the world,
but this usage seems objection able, since, in a purely physical world,
things would happen without there being any experience. It is only
mnemic phenomena that embody experience. We may say that an animal
"experiences" an occurrence when this occurrence modifies the animal's
subsequent behaviour, i.e. when it is the mnemic portion of the cause of
future occurrences in the animal's life. The burnt child that fears the
fire has "experienced" the fire, whereas a stick that has been thrown on
and taken off again has not "experienced" anything, since it offers
no more resistance than before to being thrown on. The essence of
"experience" is the modification of behaviour produced by what is
experienced. We might, in fact, define one chain of experience, or one
biography, as a series of occurrences linked by mnemic causation. I
think it is this characteristic, more than any other, that distinguishes
sciences dealing with living organisms from physics.
The best writer on mnemic phenomena known to me is Richard Semon, the
fundamental part of whose theory I shall endeavour to summarize before
going further:
When an organism, either animal or plant, is subjected to a stimulus,
producing in it some state of excitement, the removal of the stimulus
allows it to return to a condition of equilibrium. But the new state
of equilibrium is different from the old, as may be seen by the changed
capacity for reaction. The state of equilibrium before the stimulus may
be called the "primary indifference-state"; that after the cessation
of the stimulus, the "secondary indifference-state." We define the
"engraphic effect" of a stimulus as the effect in making a difference
between the primary and secondary indifference-states, and this
difference itself we define as the "engram" due to the stimulus. "Mnemic
phenomena" are defined as those due to engrams; in animals, they are
specially associated with the nervous system, but not exclusively, even
in man.
When two stimuli occur together, one of them, occurring afterwards,
may call out the reaction for the other also. We call this an "ekphoric
influence," and stimuli having this character are called "ekphoric
stimuli." In such a case we call the engrams of the two stimuli
"associated." All simultaneously generated engrams are associated; there
is also association of successively aroused engrams, though this is
reducible to simultaneous association. In fact, it is not an isolated
stimulus that leaves an engram, but the totality of the stimuli at any
moment; consequently any portion of this totality tends, if it recurs,
to arouse the whole reaction which was aroused before. Semon holds that
engrams can be inherited, and that an animal's innate habits may be due
to the experience of its ancestors; on this subject he refers to Samuel
Butler.
Semon formulates two "mnemic principles." The first, or "Law of
Engraphy," is as follows: "All simultaneous excitements in an organism
form a connected simultaneous excitement-complex, which as such works
engraphically, i.e. leaves behind a connected engram-complex, which
in so far forms a whole" ("Die mnemischen Empfindungen," p. 146).
The second mnemic principle, or "Law of Ekphory," is as follows:
"The partial return of the energetic situation which formerly worked
engraphically operates ekphorically on a simultaneous engram-complex"
(ib., p. 173). These two laws together represent in part a hypothesis
(the engram), and in part an observable fact. The observable fact is
that, when a certain complex of stimuli has originally caused a certain
complex of reactions, the recurrence of part of the stimuli tends to
cause the recurrence of the whole of the reactions.
Semon's applications of his fundamental ideas in various directions are
interesting and ingenious. Some of them will concern us later, but for
the present it is the fundamental character of mnemic phenomena that is
in question.
Concerning the nature of an engram, Semon confesses that at present it
is impossible to say more than that it must consist in some material
alteration in the body of the organism ("Die mnemischen Empfindungen,"
p. 376). It is, in fact, hypothetical, invoked for theoretical uses, and
not an outcome of direct observation. No doubt physiology, especially
the disturbances of memory through lesions in the brain, affords grounds
for this hypothesis; nevertheless it does remain a hypothesis, the
validity of which will be discussed at the end of this lecture.
I am inclined to think that, in the present state of physiology, the
introduction of the engram does not serve to simplify the account of
mnemic phenomena. We can, I think, formulate the known laws of such
phenomena in terms, wholly, of observable facts, by recognizing
provisionally what we may call "mnemic causation." By this I mean that
kind of causation of which I spoke at the beginning of this lecture,
that kind, namely, in which the proximate cause consists not merely of a
present event, but of this together with a past event. I do not wish to
urge that this form of causation is ultimate, but that, in the present
state of our knowledge, it affords a simplification, and enables us
to state laws of behaviour in less hypothetical terms than we should
otherwise have to employ.
The clearest instance of what I mean is recollection of a past event.
What we observe is that certain present stimuli lead us to recollect
certain occurrences, but that at times when we are not recollecting
them, there is nothing discoverable in our minds that could be called
memory of them. Memories, as mental facts, arise from time to time,
but do not, so far as we can see, exist in any shape while they are
"latent." In fact, when we say that they are "latent," we mean merely
that they will exist under certain circumstances. If, then, there is
to be some standing difference between the person who can remember a
certain fact and the person who cannot, that standing difference must
be, not in anything mental, but in the brain. It is quite probable that
there is such a difference in the brain, but its nature is unknown and
it remains hypothetical. Everything that has, so far, been made matter
of observation as regards this question can be put together in the
statement: When a certain complex of sensations has occurred to a man,
the recurrence of part of the complex tends to arouse the recollection
of the whole. In like manner, we can collect all mnemic phenomena in
living organisms under a single law, which contains what is hitherto
verifiable in Semon's two laws. This single law is:
IF A COMPLEX STIMULUS A HAS CAUSED A COMPLEX REACTION B IN AN ORGANISM,
THE OCCURRENCE OF A PART OF A ON A FUTURE OCCASION TENDS TO CAUSE THE
WHOLE REACTION B.
This law would need to be supplemented by some account of the influence
of frequency, and so on; but it seems to contain the essential
characteristic of mnemic phenomena, without admixture of anything
hypothetical.
Whenever the effect resulting from a stimulus to an organism differs
according to the past history of the organism, without our being able
actually to detect any relevant difference in its present structure,
we will speak of "mnemic causation," provided we can discover laws
embodying the influence of the past. In ordinary physical causation,
as it appears to common sense, we have approximate uniformities of
sequence, such as "lightning is followed by thunder," "drunkenness
is followed by headache," and so on. None of these sequences are
theoretically invariable, since something may intervene to disturb
them. In order to obtain invariable physical laws, we have to proceed to
differential equations, showing the direction of change at each moment,
not the integral change after a finite interval, however short. But
for the purposes of daily life many sequences are to all in tents and
purposes invariable. With the behaviour of human beings, however, this
is by no means the case. If you say to an Englishman, "You have a smut
on your nose," he will proceed to remove it, but there will be no such
effect if you say the same thing to a Frenchman who knows no English.
The effect of words upon the hearer is a mnemic phenomena, since it
depends upon the past experience which gave him understanding of the
words. If there are to be purely psychological causal laws, taking no
account of the brain and the rest of the body, they will have to be of
the form, not "X now causes Y now," but--
"A, B, C,... in the past, together with X now, cause Y now." For it
cannot be successfully maintained that our understanding of a word, for
example, is an actual existent content of the mind at times when we
are not thinking of the word. It is merely what may be called a
"disposition," i.e. it is capable of being aroused whenever we hear the
word or happen to think of it. A "disposition" is not something actual,
but merely the mnemic portion of a mnemic causal law.
In such a law as "A, B, C,... in the past, together with X now, cause
Y now," we will call A, B, C,... the mnemic cause, X the occasion or
stimulus, and Y the reaction. All cases in which experience influences
behaviour are instances of mnemic causation.
Believers in psycho-physical parallelism hold that psychology can
theoretically be freed entirely from all dependence on physiology or
physics. That is to say, they believe that every psychical event has
a psychical cause and a physical concomitant. If there is to be
parallelism, it is easy to prove by mathematical logic that the
causation in physical and psychical matters must be of the same sort,
and it is impossible that mnemic causation should exist in psychology
but not in physics. But if psychology is to be independent of
physiology, and if physiology can be reduced to physics, it would seem
that mnemic causation is essential in psychology. Otherwise we shall be
compelled to believe that all our knowledge, all our store of images
and memories, all our mental habits, are at all times existing in some
latent mental form, and are not merely aroused by the stimuli which lead
to their display. This is a very difficult hypothesis. It seems to me
that if, as a matter of method rather than metaphysics, we desire to
obtain as much independence for psychology as is practically feasible,
we shall do better to accept mnemic causation in psychology protem,
and therefore reject parallelism, since there is no good ground for
admitting mnemic causation in physics.
It is perhaps worth while to observe that mnemic causation is what led
Bergson to deny that there is causation at all in the psychical sphere.
He points out, very truly, that the same stimulus, repeated, does not
have the same consequences, and he argues that this is contrary to the
maxim, "same cause, same effect." It is only necessary, however, to take
account of past occurrences and include them with the cause, in order
to re-establish the maxim, and the possibility of psychological causal
laws. The metaphysical conception of a cause lingers in our manner of
viewing causal laws: we want to be able to FEEL a connection between
cause and effect, and to be able to imagine the cause as "operating."
This makes us unwilling to regard causal laws as MERELY observed
uniformities of sequence; yet that is all that science has to offer.
To ask why such-and-such a kind of sequence occurs is either to ask a
meaningless question, or to demand some more general kind of sequence
which includes the one in question. The widest empirical laws of
sequence known at any time can only be "explained" in the sense of being
subsumed by later discoveries under wider laws; but these wider laws,
until they in turn are subsumed, will remain brute facts, resting solely
upon observation, not upon some supposed inherent rationality.
There is therefore no a priori objection to a causal law in which part
of the cause has ceased to exist. To argue against such a law on the
ground that what is past cannot operate now, is to introduce the old
metaphysical notion of cause, for which science can find no place. The
only reason that could be validly alleged against mnemic causation would
be that, in fact, all the phenomena can be explained without it. They
are explained without it by Semon's "engram," or by any theory which
regards the results of experience as embodied in modifications of
the brain and nerves. But they are not explained, unless with extreme
artificiality, by any theory which regards the latent effects of
experience as psychical rather than physical. Those who desire to make
psychology as far as possible independent of physiology would do well,
it seems to me, if they adopted mnemic causation. For my part, however,
I have no such desire, and I shall therefore endeavour to state the
grounds which occur to me in favour of some such view as that of the
"engram."
One of the first points to be urged is that mnemic phenomena are just
as much to be found in physiology as in psychology. They are even to
be found in plants, as Sir Francis Darwin pointed out (cf. Semon, "Die
Mneme," 2nd edition, p. 28 n.). Habit is a characteristic of the body
at least as much as of the mind. We should, therefore, be compelled
to allow the intrusion of mnemic causation, if admitted at all, into
non-psychological regions, which ought, one feels, to be subject only to
causation of the ordinary physical sort. The fact is that a great deal
of what, at first sight, distinguishes psychology from physics is found,
on examination, to be common to psychology and physiology; this whole
question of the influence of experience is a case in point. Now it
is possible, of course, to take the view advocated by Professor J. S.
Haldane, who contends that physiology is not theoretically reducible to
physics and chemistry.* But the weight of opinion among physiologists
appears to be against him on this point; and we ought certainly to
require very strong evidence before admitting any such breach of
continuity as between living and dead matter. The argument from the
existence of mnemic phenomena in physiology must therefore be allowed a
certain weight against the hypothesis that mnemic causation is ultimate.
* See his "The New Physiology and Other Addresses," Griffin,
1919, also the symposium, "Are Physical, Biological and
Psychological Categories Irreducible?" in "Life and Finite
Individuality," edited for the Aristotelian Society, with an
Introduction. By H. Wildon Carr, Williams & Norgate, 1918.
The argument from the connection of brain-lesions with loss of memory is
not so strong as it looks, though it has also, some weight. What we
know is that memory, and mnemic phenomena generally, can be disturbed or
destroyed by changes in the brain. This certainly proves that the brain
plays an essential part in the causation of memory, but does not prove
that a certain state of the brain is, by itself, a sufficient condition
for the existence of memory. Yet it is this last that has to be proved.
The theory of the engram, or any similar theory, has to maintain that,
given a body and brain in a suitable state, a man will have a certain
memory, without the need of any further conditions. What is known,
however, is only that he will not have memories if his body and brain
are not in a suitable state. That is to say, the appropriate state
of body and brain is proved to be necessary for memory, but not to be
sufficient. So far, therefore, as our definite knowledge goes, memory
may require for its causation a past occurrence as well as a certain
present state of the brain.
In order to prove conclusively that mnemic phenomena arise whenever
certain physiological conditions are fulfilled, we ought to be able
actually to see differences between the brain of a man who speaks
English and that of a man who speaks French, between the brain of a man
who has seen New York and can recall it, and that of a man who has never
seen that city. It may be that the time will come when this will be
possible, but at present we are very far removed from it. At present,
there is, so far as I am aware, no good evidence that every difference
between the knowledge possessed by A and that possessed by B is
paralleled by some difference in their brains. We may believe that
this is the case, but if we do, our belief is based upon analogies
and general scientific maxims, not upon any foundation of detailed
observation. I am myself inclined, as a working hypothesis, to adopt
the belief in question, and to hold that past experience only affects
present behaviour through modifications of physiological structure. But
the evidence seems not quite conclusive, so that I do not think we ought
to forget the other hypothesis, or to reject entirely the possibility
that mnemic causation may be the ultimate explanation of mnemic
phenomena. I say this, not because I think it LIKELY that mnemic
causation is ultimate, but merely because I think it POSSIBLE, and
because it often turns out important to the progress of science to
remember hypotheses which have previously seemed improbable.