One of the main purposes of these lectures is to give grounds for
the belief that the distinction between mind and matter is not so
fundamental as is commonly supposed. In the preceding lecture I dealt in
outline with the physical side of this problem. I attempted to show
that what we call a material object is not itself a substance, but is
a system of particulars analogous in their nature to sensations, and in
fact often including actual sensations among their number. In this
way the stuff of which physical objects are composed is brought into
relation with the stuff of which part, at least, of our mental life is
composed.
There is, however, a converse task which is equally necessary for our
thesis, and that is, to show that the stuff of our mental life is devoid
of many qualities which it is commonly supposed to have, and is not
possessed of any attributes which make it incapable of forming part of
the world of matter. In the present lecture I shall begin the arguments
for this view.
Corresponding to the supposed duality of matter and mind, there are, in
orthodox psychology, two ways of knowing what exists. One of these, the
way of sensation and external perception, is supposed to furnish data
for our knowledge of matter, the other, called "introspection," is
supposed to furnish data for knowledge of our mental processes. To
common sense, this distinction seems clear and easy. When you see a
friend coming along the street, you acquire knowledge of an external,
physical fact; when you realize that you are glad to meet him, you
acquire knowledge of a mental fact. Your dreams and memories and
thoughts, of which you are often conscious, are mental facts, and the
process by which you become aware of them SEEMS to be different from
sensation. Kant calls it the "inner sense"; sometimes it is spoken of
as "consciousness of self"; but its commonest name in modern English
psychology is "introspection." It is this supposed method of acquiring
knowledge of our mental processes that I wish to analyse and examine in
this lecture.
I will state at the outset the view which I shall aim at establishing.
I believe that the stuff of our mental life, as opposed to its relations
and structure, consists wholly of sensations and images. Sensations are
connected with matter in the way that I tried to explain in Lecture V,
i.e. each is a member of a system which is a certain physical object.
Images, though they USUALLY have certain characteristics, especially
lack of vividness, that distinguish them from sensations, are not
INVARIABLY so distinguished, and cannot therefore be defined by these
characteristics. Images, as opposed to sensations, can only be defined
by their different causation: they are caused by association with a
sensation, not by a stimulus external to the nervous system--or perhaps
one should say external to the brain, where the higher animals are
concerned. The occurrence of a sensation or image does not in itself
constitute knowledge but any sensation or image may come to be known
if the conditions are suitable. When a sensation--like the hearing of a
clap of thunder--is normally correlated with closely similar sensations
in our neighbours, we regard it as giving knowledge of the external
world, since we regard the whole set of similar sensations as due to
a common external cause. But images and bodily sensations are not so
correlated. Bodily sensations can be brought into a correlation by
physiology, and thus take their place ultimately among sources of
knowledge of the physical world. But images cannot be made to fit in
with the simultaneous sensations and images of others. Apart from their
hypothetical causes in the brain, they have a causal connection
with physical objects, through the fact that they are copies of past
sensations; but the physical objects with which they are thus connected
are in the past, not in the present. These images remain private in
a sense in which sensations are not. A sensation SEEMS to give us
knowledge of a present physical object, while an image does not, except
when it amounts to a hallucination, and in this case the seeming is
deceptive. Thus the whole context of the two occurrences is different.
But in themselves they do not differ profoundly, and there is no reason
to invoke two different ways of knowing for the one and for the other.
Consequently introspection as a separate kind of knowledge disappears.
The criticism of introspection has been in the main the work of American
psychologists. I will begin by summarizing an article which seems to me
to afford a good specimen of their arguments, namely, "The Case against
Introspection," by Knight Dunlap ("Psychological Review," vol xix, No.
5, pp. 404-413, September, 1912). After a few historical quotations,
he comes to two modern defenders of introspection, Stout and James. He
quotes from Stout such statements as the following: "Psychical states as
such become objects only when we attend to them in an introspective way.
Otherwise they are not themselves objects, but only constituents of the
process by which objects are recognized" ("Manual," 2nd edition, p. 134.
The word "recognized" in Dunlap's quotation should be "cognized.") "The
object itself can never be identified with the present modification of
the individual's consciousness by which it is cognized" (ib. p. 60).
This is to be true even when we are thinking about modifications of
our own consciousness; such modifications are to be always at least
partially distinct from the conscious experience in which we think of
them.
At this point I wish to interrupt the account of Knight Dunlap's article
in order to make some observations on my own account with reference to
the above quotations from Stout. In the first place, the conception of
"psychical states" seems to me one which demands analysis of a somewhat
destructive character. This analysis I shall give in later lectures as
regards cognition; I have already given it as regards desire. In the
second place, the conception of "objects" depends upon a certain view
as to cognition which I believe to be wholly mistaken, namely, the view
which I discussed in my first lecture in connection with Brentano.
In this view a single cognitive occurrence contains both content and
object, the content being essentially mental, while the object is
physical except in introspection and abstract thought. I have already
criticized this view, and will not dwell upon it now, beyond saying
that "the process by which objects are cognized" appears to be a very
slippery phrase. When we "see a table," as common sense would say, the
table as a physical object is not the "object" (in the psychological
sense) of our perception. Our perception is made up of sensations,
images and beliefs, but the supposed "object" is something inferential,
externally related, not logically bound up with what is occurring in us.
This question of the nature of the object also affects the view we take
of self-consciousness. Obviously, a "conscious experience" is different
from a physical object; therefore it is natural to assume that a thought
or perception whose object is a conscious experience must be different
from a thought or perception whose object is a physical object. But if
the relation to the object is inferential and external, as I maintain,
the difference between two thoughts may bear very little relation to
the difference between their objects. And to speak of "the present
modification of the individual's consciousness by which an object is
cognized" is to suggest that the cognition of objects is a far more
direct process, far more intimately bound up with the objects, than I
believe it to be. All these points will be amplified when we come to the
analysis of knowledge, but it is necessary briefly to state them now in
order to suggest the atmosphere in which our analysis of "introspection"
is to be carried on.
Another point in which Stout's remarks seem to me to suggest what I
regard as mistakes is his use of "consciousness." There is a view which
is prevalent among psychologists, to the effect that one can speak of "a
conscious experience" in a curious dual sense, meaning, on the one hand,
an experience which is conscious of something, and, on the other hand,
an experience which has some intrinsic nature characteristic of what
is called "consciousness." That is to say, a "conscious experience" is
characterized on the one hand by relation to its object and on the
other hand by being composed of a certain peculiar stuff, the stuff of
"consciousness." And in many authors there is yet a third confusion: a
"conscious experience," in this third sense, is an experience of
which we are conscious. All these, it seems to me, need to be clearly
separated. To say that one occurrence is "conscious" of another is, to
my mind, to assert an external and rather remote relation between them.
I might illustrate it by the relation of uncle and nephew a man becomes
an uncle through no effort of his own, merely through an occurrence
elsewhere. Similarly, when you are said to be "conscious" of a table,
the question whether this is really the case cannot be decided by
examining only your state of mind: it is necessary also to ascertain
whether your sensation is having those correlates which past experience
causes you to assume, or whether the table happens, in this case, to be
a mirage. And, as I explained in my first lecture, I do not believe that
there is any "stuff" of consciousness, so that there is no intrinsic
character by which a "conscious" experience could be distinguished from
any other.
After these preliminaries, we can return to Knight Dunlap's article.
His criticism of Stout turns on the difficulty of giving any empirical
meaning to such notions as the "mind" or the "subject"; he quotes from
Stout the sentence: "The most important drawback is that the mind, in
watching its own workings, must necessarily have its attention divided
between two objects," and he concludes: "Without question, Stout is
bringing in here illicitly the concept of a single observer, and his
introspection does not provide for the observation of this observer;
for the process observed and the observer are distinct" (p. 407).
The objections to any theory which brings in the single observer were
considered in Lecture I, and were acknowledged to be cogent. In so
far, therefore, as Stout's theory of introspection rests upon this
assumption, we are compelled to reject it. But it is perfectly possible
to believe in introspection without supposing that there is a single
observer.
William James's theory of introspection, which Dunlap next examines,
does not assume a single observer. It changed after the publication
of his "Psychology," in consequence of his abandoning the dualism of
thought and things. Dunlap summarizes his theory as follows:
"The essential points in James's scheme of consciousness are SUBJECT,
OBJECT, and a KNOWING of the object by the subject. The difference
between James's scheme and other schemes involving the same terms is
that James considers subject and object to be the same thing, but at
different times In order to satisfy this requirement James supposes a
realm of existence which he at first called 'states of consciousness' or
'thoughts,' and later, 'pure experience,' the latter term including both
the 'thoughts' and the 'knowing.' This scheme, with all its magnificent
artificiality, James held on to until the end, simply dropping the
term consciousness and the dualism between the thought and an external
reality"(p. 409).
He adds: "All that James's system really amounts to is the
acknowledgment that a succession of things are known, and that they are
known by something. This is all any one can claim, except for the
fact that the things are known together, and that the knower for the
different items is one and the same" (ib.).
In this statement, to my mind, Dunlap concedes far more than James did
in his later theory. I see no reason to suppose that "the knower for
different items is one and the same," and I am convinced that this
proposition could not possibly be ascertained except by introspection of
the sort that Dunlap rejects. The first of these points must wait until
we come to the analysis of belief: the second must be considered now.
Dunlap's view is that there is a dualism of subject and object, but that
the subject can never become object, and therefore there is no awareness
of an awareness. He says in discussing the view that introspection
reveals the occurrence of knowledge: "There can be no denial of the
existence of the thing (knowing) which is alleged to be known or
observed in this sort of 'introspection.' The allegation that the
knowing is observed is that which may be denied. Knowing there certainly
is; known, the knowing certainly is not"(p. 410). And again: "I am
never aware of an awareness" (ib.). And on the next page: "It may sound
paradoxical to say that one cannot observe the process (or relation) of
observation, and yet may be certain that there is such a process: but
there is really no inconsistency in the saying. How do I know that there
is awareness? By being aware of something. There is no meaning in the
term 'awareness' which is not expressed in the statement 'I am aware of
a colour (or what-not).'"
But the paradox cannot be so lightly disposed of. The statement "I am
aware of a colour" is assumed by Knight Dunlap to be known to be true,
but he does not explain how it comes to be known. The argument against
him is not conclusive, since he may be able to show some valid way of
inferring our awareness. But he does not suggest any such way. There is
nothing odd in the hypothesis of beings which are aware of objects, but
not of their own awareness; it is, indeed, highly probable that young
children and the higher animals are such beings. But such beings cannot
make the statement "I am aware of a colour," which WE can make. We have,
therefore, some knowledge which they lack. It is necessary to Knight
Dunlap's position to maintain that this additional knowledge is purely
inferential, but he makes no attempt to show how the inference is
possible. It may, of course, be possible, but I cannot see how. To my
mind the fact (which he admits) that we know there is awareness, is ALL
BUT decisive against his theory, and in favour of the view that we can
be aware of an awareness.
Dunlap asserts (to return to James) that the real ground for James's
original belief in introspection was his belief in two sorts of
objects, namely, thoughts and things. He suggests that it was a
mere inconsistency on James's part to adhere to introspection after
abandoning the dualism of thoughts and things. I do not wholly agree
with this view, but it is difficult to disentangle the difference as to
introspection from the difference as to the nature of knowing. Dunlap
suggests (p. 411) that what is called introspection really consists of
awareness of "images," visceral sensations, and so on. This view, in
essence, seems to me sound. But then I hold that knowing itself consists
of such constituents suitably related, and that in being aware of them
we are sometimes being aware of instances of knowing. For this reason,
much as I agree with his view as to what are the objects of which
there is awareness, I cannot wholly agree with his conclusion as to the
impossibility of introspection.
The behaviourists have challenged introspection even more vigorously
than Knight Dunlap, and have gone so far as to deny the existence of
images. But I think that they have confused various things which
are very commonly confused, and that it is necessary to make several
distinctions before we can arrive at what is true and what false in the
criticism of introspection.
I wish to distinguish three distinct questions, any one of which may be
meant when we ask whether introspection is a source of knowledge. The
three questions are as follows:
(1) Can we observe anything about ourselves which we cannot observe
about other people, or is everything we can observe PUBLIC, in the sense
that another could also observe it if suitably placed?
(2) Does everything that we can observe obey the laws of physics and
form part of the physical world, or can we observe certain things that
lie outside physics?
(3) Can we observe anything which differs in its intrinsic nature from
the constituents of the physical world, or is everything that we can
observe composed of elements intrinsically similar to the constituents
of what is called matter?
Any one of these three questions may be used to define introspection. I
should favour introspection in the sense of the first question, i.e. I
think that some of the things we observe cannot, even theoretically, be
observed by any one else. The second question, tentatively and for
the present, I should answer in favour of introspection; I think that
images, in the actual condition of science, cannot be brought under the
causal laws of physics, though perhaps ultimately they may be. The
third question I should answer adversely to introspection I think that
observation shows us nothing that is not composed of sensations and
images, and that images differ from sensations in their causal laws, not
intrinsically. I shall deal with the three questions successively.
(1) PUBLICITY OR PRIVACY OF WHAT IS OBSERVED. Confining ourselves, for
the moment, to sensations, we find that there are different degrees
of publicity attaching to different sorts of sensations. If you feel a
toothache when the other people in the room do not, you are in no way
surprised; but if you hear a clap of thunder when they do not, you begin
to be alarmed as to your mental condition. Sight and hearing are the
most public of the senses; smell only a trifle less so; touch, again, a
trifle less, since two people can only touch the same spot successively,
not simultaneously. Taste has a sort of semi-publicity, since people
seem to experience similar taste-sensations when they eat similar foods;
but the publicity is incomplete, since two people cannot eat actually
the same piece of food.
But when we pass on to bodily sensations--headache, toothache, hunger,
thirst, the feeling of fatigue, and so on--we get quite away from
publicity, into a region where other people can tell us what they feel,
but we cannot directly observe their feeling. As a natural result of
this state of affairs, it has come to be thought that the public senses
give us knowledge of the outer world, while the private senses only give
us knowledge as to our own bodies. As regards privacy, all images, of
whatever sort, belong with the sensations which only give knowledge of
our own bodies, i.e. each is only observable by one observer. This is
the reason why images of sight and hearing are more obviously different
from sensations of sight and hearing than images of bodily sensations
are from bodily sensations; and that is why the argument in favour of
images is more conclusive in such cases as sight and hearing than in
such cases as inner speech.
The whole distinction of privacy and publicity, however, so long as we
confine ourselves to sensations, is one of degree, not of kind. No
two people, there is good empirical reason to think, ever have exactly
similar sensations related to the same physical object at the same
moment; on the other hand, even the most private sensation has
correlations which would theoretically enable another observer to infer
it.
That no sensation is ever completely public, results from differences of
point of view. Two people looking at the same table do not get the same
sensation, because of perspective and the way the light falls. They get
only correlated sensations. Two people listening to the same sound do
not hear exactly the same thing, because one is nearer to the source of
the sound than the other, one has better hearing than the other, and
so on. Thus publicity in sensations consists, not in having PRECISELY
similar sensations, but in having more or less similar sensations
correlated according to ascertainable laws. The sensations which strike
us as public are those where the correlated sensations are very similar
and the correlations are very easy to discover. But even the most
private sensations have correlations with things that others can
observe. The dentist does not observe your ache, but he can see the
cavity which causes it, and could guess that you are suffering even
if you did not tell him. This fact, however, cannot be used, as Watson
would apparently wish, to extrude from science observations which are
private to one observer, since it is by means of many such observations
that correlations are established, e.g. between toothaches and cavities.
Privacy, therefore does not by itself make a datum unamenable to
scientific treatment. On this point, the argument against introspection
must be rejected.
(2) DOES EVERYTHING OBSERVABLE OBEY THE LAWS OF PHYSICS? We come now to
the second ground of objection to introspection, namely, that its data
do not obey the laws of physics. This, though less emphasized, is,
I think, an objection which is really more strongly felt than the
objection of privacy. And we obtain a definition of introspection more
in harmony with usage if we define it as observation of data not subject
to physical laws than if we define it by means of privacy. No one would
regard a man as introspective because he was conscious of having a
stomach ache. Opponents of introspection do not mean to deny the obvious
fact that we can observe bodily sensations which others cannot observe.
For example, Knight Dunlap contends that images are really muscular
contractions,* and evidently regards our awareness of muscular
contractions as not coming under the head of introspection. I think it
will be found that the essential characteristic of introspective data,
in the sense which now concerns us, has to do with LOCALIZATION: either
they are not localized at all, or they are localized, like visual
images, in a place already physically occupied by something which would
be inconsistent with them if they were regarded as part of the physical
world. If you have a visual image of your friend sitting in a chair
which in fact is empty, you cannot locate the image in your body,
because it is visual, nor (as a physical phenomenon) in the chair,
because the chair, as a physical object, is empty. Thus it seems to
follow that the physical world does not include all that we are aware
of, and that images, which are introspective data, have to be regarded,
for the present, as not obeying the laws of physics; this is, I think,
one of the chief reasons why an attempt is made to reject them. I
shall try to show in Lecture VIII that the purely empirical reasons for
accepting images are overwhelming. But we cannot be nearly so certain
that they will not ultimately be brought under the laws of physics. Even
if this should happen, however, they would still be distinguishable
from sensations by their proximate causal laws, as gases remain
distinguishable from solids.
* "Psychological Review," 1916, "Thought-Content and
Feeling," p. 59. See also ib., 1912, "The Nature of
Perceived Relations," where he says: "'Introspection,'
divested of its mythological suggestion of the observing of
consciousness, is really the observation of bodily
sensations (sensibles) and feelings (feelables)"(p. 427 n.).
(3) CAN WE OBSERVE ANYTHING INTRINSICALLY DIFFERENT FROM SENSATIONS? We
come now to our third question concerning introspection. It is commonly
thought that by looking within we can observe all sorts of things that
are radically different from the constituents of the physical world,
e.g. thoughts, beliefs, desires, pleasures, pains and emotions. The
difference between mind and matter is increased partly by emphasizing
these supposed introspective data, partly by the supposition that matter
is composed of atoms or electrons or whatever units physics may at the
moment prefer. As against this latter supposition, I contend that
the ultimate constituents of matter are not atoms or electrons, but
sensations, and other things similar to sensations as regards extent and
duration. As against the view that introspection reveals a mental world
radically different from sensations, I propose to argue that thoughts,
beliefs, desires, pleasures, pains and emotions are all built up out
of sensations and images alone, and that there is reason to think that
images do not differ from sensations in their intrinsic character. We
thus effect a mutual rapprochement of mind and matter, and reduce the
ultimate data of introspection (in our second sense) to images alone. On
this third view of the meaning of introspection, therefore, our decision
is wholly against it.
There remain two points to be considered concerning introspection. The
first is as to how far it is trustworthy; the second is as to whether,
even granting that it reveals no radically different STUFF from that
revealed by what might be called external perception, it may not reveal
different RELATIONS, and thus acquire almost as much importance as is
traditionally assigned to it.
To begin with the trustworthiness of introspection. It is common among
certain schools to regard the knowledge of our own mental processes as
incomparably more certain than our knowledge of the "external" world;
this view is to be found in the British philosophy which descends from
Hume, and is present, somewhat veiled, in Kant and his followers.
There seems no reason whatever to accept this view. Our spontaneous,
unsophisticated beliefs, whether as to ourselves or as to the outer
world, are always extremely rash and very liable to error. The
acquisition of caution is equally necessary and equally difficult in
both directions. Not only are we often un aware of entertaining a
belief or desire which exists in us; we are often actually mistaken. The
fallibility of introspection as regards what we desire is made evident
by psycho-analysis; its fallibility as to what we know is easily
demonstrated. An autobiography, when confronted by a careful editor
with documentary evidence, is usually found to be full of obviously
inadvertent errors. Any of us confronted by a forgotten letter written
some years ago will be astonished to find how much more foolish our
opinions were than we had remembered them as being. And as to the
analysis of our mental operations--believing, desiring, willing, or what
not--introspection unaided gives very little help: it is necessary to
construct hypotheses and test them by their consequences, just as we do
in physical science. Introspection, therefore, though it is one among
our sources of knowledge, is not, in isolation, in any degree more
trustworthy than "external" perception.
I come now to our second question: Does introspection give us materials
for the knowledge of relations other than those arrived at by reflecting
upon external perception? It might be contended that the essence of what
is "mental" consists of relations, such as knowing for example, and that
our knowledge concerning these essentially mental relations is entirely
derived from introspection. If "knowing" were an unanalysable relation,
this view would be incontrovertible, since clearly no such relation
forms part of the subject matter of physics. But it would seem that
"knowing" is really various relations, all of them complex. Therefore,
until they have been analysed, our present question must remain
unanswered I shall return to it at the end of the present course of
lectures.