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The Analysis of Mind

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Zealanders find the falsehood of this proposition self-evident.
Therefore, if self-evidence is a guarantee of truth, our
ancestors must have been mistaken in thinking their beliefs about
the Antipodes self-evident. Meinong meets this difficulty by
saying that some beliefs are falsely thought to be self-evident,
but in the case of others it is self-evident that they are
self-evident, and these are wholly reliable. Even this, however,
does not remove the practical risk of error, since we may
mistakenly believe it self-evident that a certain belief is
self-evident. To remove all risk of error, we shall need an
endless series of more and more complicated self-evident beliefs,
which cannot possibly be realized in practice. It would seem,
therefore, that self-evidence is useless as a practical criterion
for insuring truth.

The same result follows from examining instances. If we take the
four instances mentioned at the beginning of this discussion, we
shall find that three of them are logical, while the fourth is a
judgment of perception. The proposition that two and two are four
follows by purely logical deduction from definitions: that means
that its truth results, not from the properties of objects, but
from the meanings of symbols. Now symbols, in mathematics, mean
what we choose; thus the feeling of self-evidence, in this case,
seems explicable by the fact that the whole matter is within our
control. I do not wish to assert that this is the whole truth
about mathematical propositions, for the question is complicated,
and I do not know what the whole truth is. But I do wish to
suggest that the feeling of self-evidence in mathematical
propositions has to do with the fact that they are concerned with
the meanings of symbols, not with properties of the world such as
external observation might reveal.

Similar considerations apply to the impossibility of a thing
being in two places at once, or of two things being in one place
at the same time. These impossibilities result logically, if I am
not mistaken, from the definitions of one thing and one place.
That is to say, they are not laws of physics, but only part of
the intellectual apparatus which we have manufactured for
manipulating physics. Their self-evidence, if this is so, lies
merely in the fact that they represent our decision as to the use
of words, not a property of physical objects.

Judgments of perception, such as "this buttercup is yellow," are
in a quite different position from judgments of logic, and their
self-evidence must have a different explanation. In order to
arrive at the nucleus of such a judgment, we will eliminate, as
far as possible, the use of words which take us beyond the
present fact, such as "buttercup" and "yellow." The simplest kind
of judgment underlying the perception that a buttercup is yellow
would seem to be the perception of similarity in two colours seen
simultaneously. Suppose we are seeing two buttercups, and we
perceive that their colours are similar. This similarity is a
physical fact, not a matter of symbols or words; and it certainly
seems to be indubitable in a way that many judgments are not.

The first thing to observe, in regard to such judgments, is that
as they stand they are vague. The word "similar" is a vague word,
since there are degrees of similarity, and no one can say where
similarity ends and dissimilarity begins. It is unlikely that our
two buttercups have EXACTLY the same colour, and if we judged
that they had we should have passed altogether outside the region
of self-evidence. To make our proposition more precise, let us
suppose that we are also seeing a red rose at the same time. Then
we may judge that the colours of the buttercups are more similar
to each other than to the colour of the rose. This judgment seems
more complicated, but has certainly gained in precision. Even
now, however, it falls short of complete precision, since
similarity is not prima facie measurable, and it would require
much discussion to decide what we mean by greater or less
similarity. To this process of the pursuit of precision there is
strictly no limit.

The next thing to observe (although I do not personally doubt
that most of our judgments of perception are true) is that it is
very difficult to define any class of such judgments which can be
known, by its intrinsic quality, to be always exempt from error.
Most of our judgments of perception involve correlations, as when
we judge that a certain noise is that of a passing cart. Such
judgments are all obviously liable to error, since there is no
correlation of which we have a right to be certain that it is
invariable. Other judgments of perception are derived from
recognition, as when we say "this is a buttercup," or even merely
"this is yellow." All such judgments entail some risk of error,
though sometimes perhaps a very small one; some flowers that look
like buttercups are marigolds, and colours that some would call
yellow others might call orange. Our subjective certainty is
usually a result of habit, and may lead us astray in
circumstances which are unusual in ways of which we are unaware.

For such reasons, no form of self-evidence seems to afford an
absolute criterion of truth. Nevertheless, it is perhaps true
that judgments having a high degree of subjective certainty are
more apt to be true than other judgments. But if this be the
case, it is a result to be demonstrated, not a premiss from which
to start in defining truth and falsehood. As an initial
guarantee, therefore, neither self-evidence nor subjective
certainty can be accepted as adequate.

(2) Coherence.--Coherence as the definition of truth is advocated
by idealists, particularly by those who in the main follow Hegel.
It is set forth ably in Mr. Joachim's book, "The Nature of Truth"
(Oxford, 1906). According to this view, any set of propositions
other than the whole of truth can be condemned on purely logical
grounds, as internally inconsistent; a single proposition, if it
is what we should ordinarily call false, contradicts itself
irremediably, while if it is what we should ordinarily call true,
it has implications which compel us to admit other propositions,
which in turn lead to others, and so on, until we find ourselves
committed to the whole of truth. One might illustrate by a very
simple example: if I say "so-and-so is a married man," that is
not a self-subsistent proposition. We cannot logically conceive
of a universe in which this proposition constituted the whole of
truth. There must be also someone who is a married woman, and who
is married to the particular man in question. The view we are
considering regards everything that can be said about any one
object as relative in the same sort of way as "so-and-so is a
married man." But everything, according to this view, is
relative, not to one or two other things, but to all other
things, so that from one bit of truth the whole can be inferred.

The fundamental objection to this view is logical, and consists
in a criticism of its doctrine as to relations. I shall omit this
line of argument, which I have developed elsewhere.* For the
moment I will content myself with saying that the powers of logic
seem to me very much less than this theory supposes. If it were
taken seriously, its advocates ought to profess that any one
truth is logically inferable from any other, and that, for
example, the fact that Caesar conquered Gaul, if adequately
considered, would enable us to discover what the weather will be
to-morrow. No such claim is put forward in practice, and the
necessity of empirical observation is not denied; but according
to the theory it ought to be.

* In the article on "The Monistic Theory of Truth" in
"Philosophical Essays" (Longmans, 1910), reprinted from the
"Proceedings of the Aristotelian Society," 1906-7.

Another objection is that no endeavour is made to show that we
cannot form a consistent whole composed partly or wholly of false
propositions, as in a novel. Leibniz's conception of many
possible worlds seems to accord much better with modern logic and
with the practical empiricism which is now universal. The attempt
to deduce the world by pure thought is attractive, and in former
times was largely supposed capable of success. But nowadays most
men admit that beliefs must be tested by observation, and not
merely by the fact that they harmonize with other beliefs. A
consistent fair-ytale is a different thing from truth, however
elaborate it may be. But to pursue this topic would lead us into
difficult technicalities; I shall therefore assume, without
further argument, that coherence is not sufficient as a
definition of truth.

III. Many difficult problems arise as regards the verifiability
of beliefs. We believe various things, and while we believe them
we think we know them. But it sometimes turns out that we were
mistaken, or at any rate we come to think we were. We must be
mistaken either in our previous opinion or in our subsequent
recantation; therefore our beliefs are not all correct, and there
are cases of belief which are not cases of knowledge. The
question of verifiability is in essence this: can we discover any
set of beliefs which are never mistaken or any test which, when
applicable, will always enable us to discriminate between true
and false beliefs? Put thus broadly and abstractly, the answer
must be negative. There is no way hitherto discovered of wholly
eliminating the risk of error, and no infallible criterion. If we
believe we have found a criterion, this belief itself may be
mistaken; we should be begging the question if we tried to test
the criterion by applying the criterion to itself.

But although the notion of an absolute criterion is chimerical,
there may be relative criteria, which increase the probability of
truth. Common sense and science hold that there are. Let us see
what they have to say.

One of the plainest cases of verification, perhaps ultimately the
only case, consists in the happening of something expected. You
go to the station believing that there will be a train at a
certain time; you find the train, you get into it, and it starts
at the expected time This constitutes verification, and is a
perfectly definite experience. It is, in a sense, the converse of
memory instead of having first sensations and then images
accompanied by belief, we have first images accompanied by belief
and then sensations. Apart from differences as to the time-order
and the accompanying feelings, the relation between image and
sensation is closely similar in the two cases of memory and
expectation; it is a relation of similarity, with difference as
to causal efficacy--broadly, the image has the psychological but
not the physical effects that the sensation would have. When an
image accompanied by an expectation-belief is thus succeeded by a
sensation which is the "meaning" of the image, we say that the
expectation-belief has been verified. The experience of
verification in this sense is exceedingly familiar; it happens
every time that accustomed activities have results that are not
surprising, in eating and walking and talking and all our daily
pursuits.

But although the experience in question is common, it is not
wholly easy to give a theoretical account of it. How do we know
that the sensation resembles the previous image? Does the image
persist in presence of the sensation, so that we can compare the
two? And even if SOME image does persist, how do we know that it
is the previous image unchanged? It does not seem as if this line
of inquiry offered much hope of a successful issue. It is better,
I think, to take a more external and causal view of the relation
of expectation to expected occurrence. If the occurrence, when it
comes, gives us the feeling of expectedness, and if the
expectation, beforehand, enabled us to act in a way which proves
appropriate to the occurrence, that must be held to constitute
the maximum of verification. We have first an expectation, then a
sensation with the feeling of expectedness related to memory of
the expectation. This whole experience, when it occurs, may be
defined as verification, and as constituting the truth of the
expectation. Appropriate action, during the period of
expectation, may be regarded as additional verification, but is
not essential. The whole process may be illustrated by looking up
a familiar quotation, finding it in the expected words, and in
the expected part of the book. In this case we can strengthen the
verification by writing down beforehand the words which we expect
to find.

I think all verification is ultimately of the above sort. We
verify a scientific hypothesis indirectly, by deducing
consequences as to the future, which subsequent experience
confirms. If somebody were to doubt whether Caesar had crossed
the Rubicon, verification could only be obtained from the future.
We could proceed to display manuscripts to our historical
sceptic, in which it was said that Caesar had behaved in this
way. We could advance arguments, verifiable by future experience,
to prove the antiquity of the manuscript from its texture,
colour, etc. We could find inscriptions agreeing with the
historian on other points, and tending to show his general
accuracy. The causal laws which our arguments would assume could
be verified by the future occurrence of events inferred by means
of them. The existence and persistence of causal laws, it is
true, must be regarded as a fortunate accident, and how long it
will continue we cannot tell. Meanwhile verification remains
often practically possible. And since it is sometimes possible,
we can gradually discover what kinds of beliefs tend to be
verified by experience, and what kinds tend to be falsified; to
the former kinds we give an increased degree of assent, to the
latter kinds a diminished degree. The process is not absolute or
infallible, but it has been found capable of sifting beliefs and
building up science. It affords no theoretical refutation of the
sceptic, whose position must remain logically unassailable; but
if complete scepticism is rejected, it gives the practical method
by which the system of our beliefs grows gradually towards the
unattainable ideal of impeccable knowledge.

IV. I come now to the purely formal definition of the truth or
falsehood of a belief. For this definition it is necessary first
of all to consider the derivation of the objective reference of a
proposition from the meanings of its component words or images.

Just as a word has meaning, so a proposition has an objective
reference. The objective reference of a proposition is a function
(in the mathematical sense) of the meanings of its component
words. But the objective reference differs from the meaning of a
word through the duality of truth and falsehood. You may believe
the proposition "to-day is Tuesday" both when, in fact, to-day is
Tuesday, and when to-day is not Tuesday. If to-day is not
Tuesday, this fact is the objective of your belief that to-day is
Tuesday. But obviously the relation of your belief to the fact is
different in this case from what it is in the case when to-day is
Tuesday. We may say, metaphorically, that when to-day is Tuesday,
your belief that it is Tuesday points TOWARDS the fact, whereas
when to-day is not Tuesday your belief points AWAY FROM the fact.
Thus the objective reference of a belief is not determined by the
fact alone, but by the direction of the belief towards or away
from the fact.* If, on a Tuesday, one man believes that it is
Tuesday while another believes that it is not Tuesday, their
beliefs have the same objective, namely the fact that it is
Tuesday but the true belief points towards the fact while the
false one points away from it. Thus, in order to define the
reference of a proposition we have to take account not only of
the objective, but also of the direction of pointing, towards the
objective in the case of a true proposition and away from it in
the case of a false one.

* I owe this way of looking at the matter to my friend Ludwig
Wittgenstein.

This mode of stating the nature of the objective reference of a
proposition is necessitated by the circumstance that there are
true and false propositions, but not true and false facts. If
to-day is Tuesday, there is not a false objective "to-day is not
Tuesday," which could be the objective of the false belief
"to-day is not Tuesday." This is the reason why two beliefs which
are each other's contradictories have the same objective. There
is, however, a practical inconvenience, namely that we cannot
determine the objective reference of a proposition, according to
this definition, unless we know whether the proposition is true
or false. To avoid this inconvenience, it is better to adopt a
slightly different phraseology, and say: The "meaning" of the
proposition "to-day is Tuesday" consists in pointing to the fact
"to-day is Tuesday" if that is a fact, or away from the fact
"to-day is not Tuesday" if that is a fact. The "meaning" of the
proposition "to-day is not Tuesday" will be exactly the opposite.
By this hypothetical form we are able to speak of the meaning of
a proposition without knowing whether it is true or false.
According to this definition, we know the meaning of a
proposition when we know what would make it true and what would
make it false, even if we do not know whether it is in fact true
or false.

The meaning of a proposition is derivative from the meanings of
its constituent words. Propositions occur in pairs, distinguished
(in simple cases) by the absence or presence of the word "not."
Two such propositions have the same objective, but opposite
meanings: when one is true, the other is false, and when one is
false, the other is true.

The purely formal definition of truth and falsehood offers little
difficulty. What is required is a formal expression of the fact
that a proposition is true when it points towards its objective,
and false when it points away from it, In very simple cases we
can give a very simple account of this: we can say that true
propositions actually resemble their objectives in a way in which
false propositions do not. But for this purpose it is necessary
to revert to image-propositions instead of word-propositions. Let
us take again the illustration of a memory-image of a familiar
room, and let us suppose that in the image the window is to the
left of the door. If in fact the window is to the left of the
door, there is a correspondence between the image and the
objective; there is the same relation between the window and the
door as between the images of them. The image-memory consists of
the image of the window to the left of the image of the door.
When this is true, the very same relation relates the terms of
the objective (namely the window and the door) as relates the
images which mean them. In this case the correspondence which
constitutes truth is very simple.

In the case we have just been considering the objective consists
of two parts with a certain relation (that of left-to-right), and
the proposition consists of images of these parts with the very
same relation. The same proposition, if it were false, would have
a less simple formal relation to its objective. If the
image-proposition consists of an image of the window to the left
of an image of the door, while in fact the window is not to the
left of the door, the proposition does not result from the
objective by the mere substitution of images for their
prototypes. Thus in this unusually simple case we can say that a
true proposition "corresponds" to its objective in a formal sense
in which a false proposition does not. Perhaps it may be possible
to modify this notion of formal correspondence in such a way as
to be more widely applicable, but if so, the modifications
required will be by no means slight. The reasons for this must
now be considered.

To begin with, the simple type of correspondence we have been
exhibiting can hardly occur when words are substituted for
images, because, in word-propositions, relations are usually
expressed by words, which are not themselves relations. Take such
a proposition as "Socrates precedes Plato." Here the word
"precedes" is just as solid as the words "Socrates" and "Plato";
it MEANS a relation, but is not a relation. Thus the objective
which makes our proposition true consists of TWO terms with a
relation between them, whereas our proposition consists of THREE
terms with a relation of order between them. Of course, it would
be perfectly possible, theoretically, to indicate a few chosen
relations, not by words, but by relations between the other
words. "Socrates-Plato" might be used to mean "Socrates precedes
Plato"; "PlaSocrates-to" might be used to mean "Plato was born
before Socrates and died after him"; and so on. But the
possibilities of such a method would be very limited. For aught I
know, there may be languages that use it, but they are not among
the languages with which I am acquainted. And in any case, in
view of the multiplicity of relations that we wish to express, no
language could advance far without words for relations. But as
soon as we have words for relations, word-propositions have
necessarily more terms than the facts to which they refer, and
cannot therefore correspond so simply with their objectives as
some image-propositions can.

The consideration of negative propositions and negative facts
introduces further complications. An image-proposition is
necessarily positive: we can image the window to the left of the
door, or to the right of the door, but we can form no image of
the bare negative "the window not to the left of the door." We
can DISBELIEVE the image-proposition expressed by "the window to
the left of the door," and our disbelief will be true if the
window is not to the left of the door. But we can form no image
of the fact that the window is not to the left of the door.
Attempts have often been made to deny such negative facts, but,
for reasons which I have given elsewhere,* I believe these
attempts to be mistaken, and I shall assume that there are
negative facts.

* "Monist," January, 1919, p. 42 ff.

Word-propositions, like image-propositions, are always positive
facts. The fact that Socrates precedes Plato is symbolized in
English by the fact that the word "precedes" occurs between the
words "Socrates" and "Plato." But we cannot symbolize the fact
that Plato does not precede Socrates by not putting the word
"precedes" between "Plato" and "Socrates." A negative fact is not
sensible, and language, being intended for communication, has to
be sensible. Therefore we symbolize the fact that Plato does not
precede Socrates by putting the words "does not precede" between
"Plato" and "Socrates." We thus obtain a series of words which is
just as positive a fact as the series "Socrates precedes Plato."
The propositions asserting negative facts are themselves positive
facts; they are merely different positive facts from those
asserting positive facts.

We have thus, as regards the opposition of positive and negative,
three different sorts of duality, according as we are dealing
with facts, image-propositions, or word-propositions. We have,
namely:

(1) Positive and negative facts;

(2) Image-propositions, which may be believed or disbelieved, but
do not allow any duality of content corresponding to positive and
negative facts;

(3) Word-propositions, which are always positive facts, but are
of two kinds: one verified by a positive objective, the other by
a negative objective.

Owing to these complications, the simplest type of correspondence
is impossible when either negative facts or negative propositions
are involved.

Even when we confine ourselves to relations between two terms
which are both imaged, it may be impossible to form an
image-proposition in which the relation of the terms is
represented by the same relation of the images. Suppose we say
"Caesar was 2,000 years before Foch," we express a certain
temporal relation between Caesar and Foch; but we cannot allow
2,000 years to elapse between our image of Caesar and our image
of Foch. This is perhaps not a fair example, since "2,000 years
before" is not a direct relation. But take a case where the
relation is direct, say, "the sun is brighter than the moon." We
can form visual images of sunshine and moonshine, and it may
happen that our image of the sunshine is the brighter of the two,
but this is by no means either necessary or sufficient. The act
of comparison, implied in our judgment, is something more than
the mere coexistence of two images, one of which is in fact
brighter than the other. It would take us too far from our main
topic if we were to go into the question what actually occurs
when we make this judgment. Enough has been said to show that the
correspondence between the belief and its objective is more
complicated in this case than in that of the window to the left
of the door, and this was all that had to be proved.

In spite of these complications, the general nature of the formal
correspondence which makes truth is clear from our instances. In
the case of the simpler kind of propositions, namely those that I
call "atomic" propositions, where there is only one word
expressing a relation, the objective which would verify our
proposition, assuming that the word "not" is absent, is obtained
by replacing each word by what it means, the word meaning a
relation being replaced by this relation among the meanings of
the other words. For example, if the proposition is "Socrates
precedes Plato," the objective which verifies it results from
replacing the word "Socrates" by Socrates, the word "Plato" by
Plato, and the word "precedes" by the relation of preceding
between Socrates and Plato. If the result of this process is a
fact, the proposition is true; if not, it is false. When our
proposition is "Socrates does not precede Plato," the conditions
of truth and falsehood are exactly reversed. More complicated
propositions can be dealt with on the same lines. In fact, the
purely formal question, which has occupied us in this last
section, offers no very formidable difficulties.

I do not believe that the above formal theory is untrue, but I do
believe that it is inadequate. It does not, for example, throw
any light upon our preference for true beliefs rather than false
ones. This preference is only explicable by taking account of the
causal efficacy of beliefs, and of the greater appropriateness of
the responses resulting from true beliefs. But appropriateness
depends upon purpose, and purpose thus becomes a vital part of
theory of knowledge.

LECTURE XIV. EMOTIONS AND WILL

On the two subjects of the present lecture I have nothing
original to say, and I am treating them only in order to complete
the discussion of my main thesis, namely that all psychic
phenomena are built up out of sensations and images alone.

Emotions are traditionally regarded by psychologists as a
separate class of mental occurrences: I am, of course, not
concerned to deny the obvious fact that they have characteristics
which make a special investigation of them necessary. What I am
concerned with is the analysis of emotions. It is clear that an
emotion is essentially complex, and we have to inquire whether it
ever contains any non-physiological material not reducible to
sensations and images and their relations.

Although what specially concerns us is the analysis of emotions,
we shall find that the more important topic is the physiological
causation of emotions. This is a subject upon which much valuable
and exceedingly interesting work has been done, whereas the bare
analysis of emotions has proved somewhat barren. In view of the
fact that we have defined perceptions, sensations, and images by
their physiological causation, it is evident that our problem of
the analysis of the emotions is bound up with the problem of
their physiological causation.

Modern views on the causation of emotions begin with what is
called the James-Lange theory. James states this view in the
following terms ("Psychology," vol. ii, p. 449):

"Our natural way of thinking about these coarser emotions, grief,
fear, rage, love, is that the mental perception of some fact
excites the mental affection called the emotion, and that this
latter state of mind gives rise to the bodily expression. My
theory, on the contrary, is that THE BODILY CHANGES FOLLOW
DIRECTLY THE PERCEPTION OF THE EXCITING FACT, AND THAT OUR
FEELING OF THE SAME CHANGES AS THEY OCCUR ~IS~ THE EMOTION
(James's italics). Common sense says: we lose our fortune, are
sorry and weep; we meet a bear, are frightened and run; we are
insulted by a rival, are angry and strike. The hypothesis here to
be defended says that this order of sequence is incorrect, that
the one mental state is not immediately induced by the other,
that the bodily manifestations must first be interposed between,
and that the more rational statement is that we feel sorry
because we cry, angry because we strike, afraid because we
tremble, and not that we cry, strike, or tremble, because we are
sorry, angry, or fearful, as the case may be. Without the bodily
states following on the perception, the latter would be purely
cognitive in form, pale, colourless, destitute of emotional
warmth."

Round this hypothesis a very voluminous literature has grown up.
The history of its victory over earlier criticism, and its
difficulties with the modern experimental work of Sherrington and
Cannon, is well told by James R. Angell in an article called "A
Reconsideration of James's Theory of Emotion in the Light of
Recent Criticisms."* In this article Angell defends James's
theory and to me--though I speak with diffidence on a question as
to which I have little competence--it appears that his defence is
on the whole successful.

* "Psychological Review," 1916.

Sherrington, by experiments on dogs, showed that many of the
usual marks of emotion were present in their behaviour even when,
by severing the spinal cord in the lower cervical region, the
viscera were cut off from all communication with the brain,
except that existing through certain cranial nerves. He mentions
the various signs which "contributed to indicate the existence of
an emotion as lively as the animal had ever shown us before the
spinal operation had been made."* He infers that the
physiological condition of the viscera cannot be the cause of the
emotion displayed under such circumstances, and concludes: "We
are forced back toward the likelihood that the visceral
expression of emotion is SECONDARY to the cerebral action
occurring with the psychical state.... We may with James accept
visceral and organic sensations and the memories and associations
of them as contributory to primitive emotion, but we must regard
them as re-enforcing rather than as initiating the psychosis."*

* Quoted by Angell, loc. cit.

Angell suggests that the display of emotion in such cases may be
due to past experience, generating habits which would require
only the stimulation of cerebral reflex arcs. Rage and some forms
of fear, however, may, he thinks, gain expression without the
brain. Rage and fear have been especially studied by Cannon,
whose work is of the greatest importance. His results are given
in his book, "Bodily Changes in Pain, Hunger, Fear and Rage" (D.
Appleton and Co., 1916).

The most interesting part of Cannon's book consists in the
investigation of the effects produced by secretion of adrenin.
Adrenin is a substance secreted into the blood by the adrenal
glands. These are among the ductless glands, the functions of
which, both in physiology and in connection with the emotions,
have only come to be known during recent years. Cannon found that
pain, fear and rage occurred in circumstances which affected the
supply of adrenin, and that an artificial injection of adrenin
could, for example, produce all the symptoms of fear. He studied
the effects of adrenin on various parts of the body; he found
that it causes the pupils to dilate, hairs to stand erect, blood
vessels to be constricted, and so on. These effects were still
produced if the parts in question were removed from the body and
kept alive artificially.*

* Cannon's work is not unconnected with that of Mosso, who
maintains, as the result of much experimental work, that "the
seat of the emotions lies in the sympathetic nervous system." An
account of the work of both these men will be found in Goddard's
"Psychology of the Normal and Sub-normal" (Kegan Paul, 1919),
chap. vii and Appendix.

Cannon's chief argument against James is, if I understand him
rightly, that similar affections of the viscera may accompany
dissimilar emotions, especially fear and rage. Various different
emotions make us cry, and therefore it cannot be true to say, as
James does, that we "feel sorry because we cry," since sometimes
we cry when we feel glad. This argument, however, is by no means
conclusive against James, because it cannot be shown that there
are no visceral differences for different emotions, and indeed it
is unlikely that this is the case.

As Angell says (loc. cit.): "Fear and joy may both cause cardiac
palpitation, but in one case we find high tonus of the skeletal
muscles, in the other case relaxation and the general sense of
weakness."

Angell's conclusion, after discussing the experiments of
Sherrington and Cannon, is: "I would therefore submit that, so
far as concerns the critical suggestions by these two
psychologists, James's essential contentions are not materially
affected." If it were necessary for me to take sides on this
question, I should agree with this conclusion; but I think my
thesis as to the analysis of emotion can be maintained without
coming to. a probably premature conclusion upon the doubtful
parts of the physiological problem.

According to our definitions, if James is right, an emotion may
be regarded as involving a confused perception of the viscera
concerned in its causation, while if Cannon and Sherrington are
right, an emotion involves a confused perception of its external
stimulus. This follows from what was said in Lecture VII. We
there defined a perception as an appearance, however irregular,
of one or more objects external to the brain. And in order to be
an appearance of one or more objects, it is only necessary that
the occurrence in question should be connected with them by a
continuous chain, and should vary when they are varied
sufficiently. Thus the question whether a mental occurrence can
be called a perception turns upon the question whether anything
can be inferred from it as to its causes outside the brain: if
such inference is possible, the occurrence in question will come
within our definition of a perception. And in that case,
according to the definition in Lecture VIII, its non-mnemic
elements will be sensations. Accordingly, whether emotions are
caused by changes in the viscera or by sensible objects, they
contain elements which are sensations according to our
definition.

An emotion in its entirety is, of course, something much more
complex than a perception. An emotion is essentially a process,
and it will be only what one may call a cross-section of the
emotion that will be a perception, of a bodily condition
according to James, or (in certain cases) of an external object
according to his opponents. An emotion in its entirety contains
dynamic elements, such as motor impulses, desires, pleasures and
pains. Desires and pleasures and pains, according to the theory
adopted in Lecture III, are characteristics of processes, not
separate ingredients. An emotion--rage, for example--will be a
certain kind of process, consisting of perceptions and (in
general) bodily movements. The desires and pleasures and pains
involved are properties of this process, not separate items in
the stuff of which the emotion is composed. The dynamic elements
in an emotion, if we are right in our analysis, contain, from our
point of view, no ingredients beyond those contained in the
processes considered in Lecture III. The ingredients of an
emotion are only sensations and images and bodily movements
succeeding each other according to a certain pattern. With this
conclusion we may leave the emotions and pass to the
consideration of the will.

The first thing to be defined when we are dealing with Will is a
VOLUNTARY MOVEMENT. We have already defined vital movements, and
we have maintained that, from a behaviourist standpoint, it is
impossible to distinguish which among such movements are reflex
and which voluntary. Nevertheless, there certainly is a
distinction. When we decide in the morning that it is time to get
up, our consequent movement is voluntary. The beating of the
heart, on the other hand, is involuntary: we can neither cause it
nor prevent it by any decision of our own, except indirectly, as
e.g. by drugs. Breathing is intermediate between the two: we
normally breathe without the help of the will, but we can alter
or stop our breathing if we choose.

James ("Psychology," chap. xxvi) maintains that the only
distinctive characteristic of a voluntary act is that it involves
an idea of the movement to be performed, made up of memory-images
of the kinaesthetic sensations which we had when the same
movement occurred on some former occasion. He points out that, on
this view, no movement can be made voluntarily unless it has
previously occurred involuntarily.*

* "Psychology," Vol. ii, pp. 492-3.

I see no reason to doubt the correctness of this view. We shall
say, then, that movements which are accompanied by kinaesthetic
sensations tend to be caused by the images of those sensations,
and when so caused are called VOLUNTARY.

Volition, in the emphatic sense, involves something more than
voluntary movement. The sort of case I am thinking of is decision
after deliberation. Voluntary movements are a part of this, but
not the whole. There is, in addition to them, a judgment: "This
is what I shall do"; there is also a sensation of tension during
doubt, followed by a different sensation at the moment of
deciding. I see no reason whatever to suppose that there is any
specifically new ingredient; sensations and images, with their
relations and causal laws, yield all that seems to be wanted for
the analysis of the will, together with the fact that
kinaesthetic images tend to cause the movements with which they
are connected. Conflict of desires is of course essential in the
causation of the emphatic kind of will: there will be for a time
kinaesthetic images of incompatible movements, followed by the
exclusive image of the movement which is said to be willed. Thus
will seems to add no new irreducible ingredient to the analysis
of the mind.

LECTURE XV. CHARACTERISTICS OF MENTAL PHENOMENA

At the end of our journey it is time to return to the question
from which we set out, namely: What is it that characterizes mind
as opposed to matter? Or, to state the same question in other
terms: How is psychology to be distinguished from physics? The
answer provisionally suggested at the outset of our inquiry was
that psychology and physics are distinguished by the nature of
their causal laws, not by their subject matter. At the same time
we held that there is a certain subject matter, namely images, to
which only psychological causal laws are applicable; this subject
matter, therefore, we assigned exclusively to psychology. But we
found no way of defining images except through their causation;
in their intrinsic character they appeared to have no universal
mark by which they could be distinguished from sensations.

In this last lecture I propose to pass in review various
suggested methods of distinguishing mind from matter. I shall
then briefly sketch the nature of that fundamental science which
I believe to be the true metaphysic, in which mind and matter
alike are seen to be constructed out of a neutral stuff, whose
causal laws have no such duality as that of psychology, but form
the basis upon which both physics and psychology are built.

In search for the definition of "mental phenomena," let us begin
with "consciousness," which is often thought to be the essence of
mind. In the first lecture I gave various arguments against the
view that consciousness is fundamental, but I did not attempt to
say what consciousness is. We must find a definition of it, if we
are to feel secure in deciding that it is not fundamental. It is
for the sake of the proof that it is not fundamental that we must
now endeavour to decide what it is.

"Consciousness," by those who regard it as fundamental, is taken
to be a character diffused throughout our mental life, distinct
from sensations and images, memories, beliefs and desires, but
present in all of them.* Dr. Henry Head, in an article which I
quoted in Lecture III, distinguishing sensations from purely
physiological occurrences, says: "Sensation, in the strict sense
of the term, demands the existence of consciousness." This
statement, at first sight, is one to which we feel inclined to
assent, but I believe we are mistaken if we do so. Sensation is
the sort of thing of which we MAY be conscious, but not a thing
of which we MUST be conscious. We have been led, in the course of
our inquiry, to admit unconscious beliefs and unconscious
desires. There is, so far as I can see, no class of mental or
other occurrences of which we are always conscious whenever they
happen.

* Cf. Lecture VI.

The first thing to notice is that consciousness must be of
something. In view of this, I should define "consciousness" in
terms of that relation of an image of a word to an object which
we defined, in Lecture XI, as "meaning." When a sensation is
followed by an image which is a "copy" of it, I think it may be
said that the existence of the image constitutes consciousness of
the sensation, provided it is accompanied by that sort of belief
which, when we reflect upon it, makes us feel that the image is a
"sign" of something other than itself. This is the sort of belief
which, in the case of memory, we expressed in the words "this
occurred"; or which, in the case of a judgment of perception,
makes us believe in qualities correlated with present sensations,
as e.g., tactile and visual qualities are correlated. The
addition of some element of belief seems required, since mere
imagination does not involve consciousness of anything, and there
can be no consciousness which is not of something. If images
alone constituted consciousness of their prototypes, such
imagination-images as in fact have prototypes would involve
consciousness of them; since this is not the case, an element of
belief must be added to the images in defining consciousness. The
belief must be of that sort that constitutes objective reference,
past or present. An image, together with a belief of this sort
concerning it, constitutes, according to our definition,
consciousness of the prototype of the image.

But when we pass from consciousness of sensations to
consciousness of objects of perception, certain further points
arise which demand an addition to our definition. A judgment of
perception, we may say, consists of a core of sensation, together
with associated images, with belief in the present existence of
an object to which sensation and images are referred in a way
which is difficult to analyse. Perhaps we might say that the
belief is not fundamentally in any PRESENT existence, but is of
the nature of an expectation: for example. when we see an object,
we expect certain sensations to result if we proceed to touch it.
Perception, then, will consist of a present sensation together
with expectations of future sensations. (This, of course, is a
reflective analysis, not an account of the way perception appears
to unchecked introspection.) But all such expectations are liable
to be erroneous, since they are based upon correlations which are
usual but not invariable. Any such correlation may mislead us in
a particular case, for example, if we try to touch a reflection
in a looking-glass under the impression that it is "real." Since
memory is fallible, a similar difficulty arises as regards
consciousness of past objects. It would seem odd to say that we
can be "conscious" of a thing which does not or did not exist.
The only way to avoid this awkwardness is to add to our
definition the proviso that the beliefs involved in consciousness
must be TRUE.

In the second place, the question arises as to whether we can be
conscious of images. If we apply our definition to this case, it
seems to demand images of images. In order, for example, to be
conscious of an image of a cat, we shall require, according to
the letter of the definition, an image which is a copy of our
image of the cat, and has this image for its prototype. Now, it
hardly seems probable, as a matter of observation, that there are
images of images, as opposed to images of sensations. We may meet
this difficulty in two ways, either by boldly denying
consciousness of images, or by finding a sense in which, by means
of a different accompanying belief, an image, instead of meaning
its prototype, can mean another image of the same prototype.

The first alternative, which denies consciousness of images, has
already been discussed when we were dealing with Introspection in
Lecture VI. We then decided that there must be, in some sense,
consciousness of images. We are therefore left with the second
suggested way of dealing with knowledge of images. According to
this second hypothesis, there may be two images of the same
prototype, such that one of them means the other, instead of
meaning the prototype. It will be remembered that we defined
meaning by association a word or image means an object, we said,
when it has the same associations as the object. But this
definition must not be interpreted too absolutely: a word or
image will not have ALL the same associations as the object which
it means. The word "cat" may be associated with the word "mat,"
but it would not happen except by accident that a cat would be
associated with a mat. And in like manner an image may have
certain associations which its prototype will not have, e.g. an
association with the word "image." When these associations are
active, an image means an image, instead of meaning its
prototype. If I have had images of a given prototype many times,
I can mean one of these, as opposed to the rest, by recollecting
the time and place or any other distinctive association of that
one occasion. This happens, for example, when a place recalls to
us some thought we previously had in that place, so that we
remember a thought as opposed to the occurrence to which it
referred. Thus we may say that we think of an image A when we
have a similar image B associated with recollections of
circumstances connected with A, but not with its prototype or
with other images of the same prototype. In this way we become
aware of images without the need of any new store of mental
contents, merely by the help of new associations. This theory, so
far as I can see, solves the problems of introspective knowledge,
without requiring heroic measures such as those proposed by
Knight Dunlap, whose views we discussed in Lecture VI.

According to what we have been saying, sensation itself is not an
instance of consciousness, though the immediate memory by which
it is apt to be succeeded is so. A sensation which is remembered
becomes an object of consciousness as soon as it begins to be
remembered, which will normally be almost immediately after its
occurrence (if at all); but while it exists it is not an object
of consciousness. If, however, it is part of a perception, say of
some familiar person, we may say that the person perceived is an
object of consciousness. For in this case the sensation is a SIGN
of the perceived object in much the same way in which a
memory-image is a sign of a remembered object. The essential
practical function of "consciousness" and "thought" is that they
enable us to act with reference to what is distant in time or
space, even though it is not at present stimulating our senses.
This reference to absent objects is possible through association
and habit. Actual sensations, in themselves, are not cases of
consciousness, because they do not bring in this reference to
what is absent. But their connection with consciousness is very
close, both through immediate memory, and through the
correlations which turn sensations into perceptions.

Enough has, I hope, been said to show that consciousness is far
too complex and accidental to be taken as the fundamental
characteristic of mind. We have seen that belief and images both
enter into it. Belief itself, as we saw in an earlier lecture, is
complex. Therefore, if any definition of mind is suggested by our
analysis of consciousness, images are what would naturally
suggest themselves. But since we found that images can only be
defined causally, we cannot deal with this suggestion, except in
connection with the difference between physical and psychological
causal laws.

I come next to those characteristics of mental phenomena which
arise out of mnemic causation. The possibility of action with
reference to what is not sensibly present is one of the things
that might be held to characterize mind. Let us take first a very
elementary example. Suppose you are in a familiar room at night,
and suddenly the light goes out. You will be able to find your
way to the door without much difficulty by means of the picture
of the room which you have in your mind. In this case visual
images serve, somewhat imperfectly it is true, the purpose which
visual sensations would otherwise serve. The stimulus to the
production of visual images is the desire to get out of the room,
which, according to what we found in Lecture III, consists
essentially of present sensations and motor impulses caused by
them. Again, words heard or read enable you to act with reference
to the matters about which they give information; here, again, a
present sensible stimulus, in virtue of habits formed in the
past, enables you to act in a manner appropriate to an object
which is not sensibly present. The whole essence of the practical
efficiency of "thought" consists in sensitiveness to signs: the
sensible presence of A, which is a sign of the present or future
existence of B, enables us to act in a manner appropriate to B.
Of this, words are the supreme example, since their effects as
signs are prodigious, while their intrinsic interest as sensible
occurrences on their own account is usually very slight. The
operation of signs may or may not be accompanied by
consciousness. If a sensible stimulus A calls up an image of B,
and we then act with reference to B, we have what may be called
consciousness of B. But habit may enable us to act in a manner
appropriate to B as soon as A appears, without ever having an
image of B. In that case, although A operates as a sign, it
operates without the help of consciousness. Broadly speaking, a
very familiar sign tends to operate directly in this manner, and
the intervention of consciousness marks an imperfectly
established habit.

The power of acquiring experience, which characterizes men and
animals, is an example of the general law that, in mnemic
causation, the causal unit is not one event at one time, but two
or more events at two or more times.& A burnt child fears the
fire, that is to say, the neighbourhood of fire has a different
effect upon a child which has had the sensations of burning than
upon one which has not. More correctly, the observed effect, when
a child which has been burnt is put near a fire, has for its
cause, not merely the neighbourhood of the fire, but this
together with the previous burning. The general formula, when an
animal has acquired experience through some event A, is that,
when B occurs at some future time, the animal to which A has
happened acts differently from an animal which A has not
happened. Thus A and B together, not either separately, must be
regarded as the cause of the animal's behaviour, unless we take
account of the effect which A has had in altering the animal's
nervous tissue, which is a matter not patent to external
observation except under very special circumstances. With this
possibility, we are brought back to causal laws,and to the
suggestion that many things which seem essentially mental are
really neural. Perhaps it is the nerves that acquire experience
rather than the mind. If so, the possibility of acquiring
experience cannot be used to define mind.*

* Cf. Lecture IV.

Very similar considerations apply to memory, if taken as the
essence of mind. A recollection is aroused by something which is
happening now, but is different from the effect which the present
occurrence would have produced if the recollected event had not
occurred. This may be accounted for by the physical effect of the
past event on the brain, making it a different instrument from
that which would have resulted from a different experience. The
causal peculiarities of memory may, therefore, have a
physiological explanation. With every special class of mental
phenomena this possibility meets us afresh. If psychology is to
be a separate science at all, we must seek a wider ground for its
separateness than any that we have been considering hitherto.

We have found that "consciousness" is too narrow to characterize
mental phenomena, and that mnemic causation is too wide. I come
now to a characteristic which, though difficult to define, comes
much nearer to what we require, namely subjectivity.

Subjectivity, as a characteristic of mental phenomena, was
considered in Lecture VII, in connection with the definition of
perception. We there decided that those particulars which
constitute the physical world can be collected into sets in two
ways, one of which makes a bundle of all those particulars that
are appearances of a given thing from different places, while the
other makes a bundle of all those particulars which are
appearances of different things from a given place. A bundle of
this latter sort, at a given time, is called a "perspective";
taken throughout a period of time, it is called a "biography."
Subjectivity is the characteristic of perspectives and
biographies, the characteristic of giving the view of the world
from a certain place. We saw in Lecture VII that this
characteristic involves none of the other characteristics that
are commonly associated with mental phenomena, such as
consciousness, experience and memory. We found in fact that it is
exhibited by a photographic plate, and, strictly speaking, by any
particular taken in conjunction with those which have the same
"passive" place in the sense defined in Lecture VII. The
particulars forming one perspective are connected together
primarily by simultaneity; those forming one biography, primarily
by the existence of direct time-relations between them. To these
are to be added relations derivable from the laws of perspective.
In all this we are clearly not in the region of psychology, as
commonly understood; yet we are also hardly in the region of
physics. And the definition of perspectives and biographies,
though it does not yet yield anything that would be commonly
called "mental," is presupposed in mental phenomena, for example
in mnemic causation: the causal unit in mnemic causation, which
gives rise to Semon's engram, is the whole of one perspective--
not of any perspective, but of a perspective in a place where
there is nervous tissue, or at any rate living tissue of some
sort. Perception also, as we saw, can only be defined in terms of
perspectives. Thus the conception of subjectivity, i.e. of the
"passive" place of a particular, though not alone sufficient to
define mind, is clearly an essential element in the definition.

I have maintained throughout these lectures that the data of
psychology do not differ in, their intrinsic character from the
data of physics. I have maintained that sensations are data for
psychology and physics equally, while images, which may be in
some sense exclusively psychological data, can only be
distinguished from sensations by their correlations, not by what
they are in themselves. It is now necessary, however, to examine
the notion of a "datum," and to obtain, if possible, a definition
of this notion.

The notion of "data" is familiar throughout science, and is
usually treated by men of science as though it were perfectly
clear. Psychologists, on the other hand, find great difficulty in
the conception. "Data" are naturally defined in terms of theory
of knowledge: they are those propositions of which the truth is
known without demonstration, so that they may be used as
premisses in proving other propositions. Further, when a
proposition which is a datum asserts the existence of something,
we say that the something is a datum, as well as the proposition
asserting its existence. Thus those objects of whose existence we
become certain through perception are said to be data.

There is some difficulty in connecting this epistemological
definition of "data" with our psychological analysis of
knowledge; but until such a connection has been effected, we have
no right to use the conception "data."

It is clear, in the first place, that there can be no datum apart
from a belief. A sensation which merely comes and goes is not a
datum; it only becomes a datum when it is remembered. Similarly,
in perception, we do not have a datum unless we have a JUDGMENT
of perception. In the sense in which objects (as opposed to
propositions) are data, it would seem natural to say that those
objects of which we are conscious are data. But consciousness, as
we have seen, is a complex notion, involving beliefs, as well as
mnemic phenomena such as are required for perception and memory.
It follows that no datum is theoretically indubitable, since no
belief is infallible; it follows also that every datum has a
greater or less degree of vagueness, since there is always some
vagueness in memory and the meaning of images.

Data are not those things of which our consciousness is earliest
in time. At every period of life, after we have become capable of
thought, some of our beliefs are obtained by inference, while
others are not. A belief may pass from either of these classes
into the other, and may therefore become, or cease to be, a
belief giving a datum. When, in what follows, I speak of data, I
do not mean the things of which we feel sure before scientific
study begins, but the things which, when a science is well
advanced, appear as affording grounds for other parts of the
science, without themselves being believed on any ground except
observation. I assume, that is to say, a trained observer, with
an analytic attention, knowing the sort of thing to look for, and
the sort of thing that will be important. What he observes is, at
the stage of science which he has reached, a datum for his
science. It is just as sophisticated and elaborate as the
theories which he bases upon it, since only trained habits and
much practice enable a man to make the kind of observation that
will be scientifically illuminating. Nevertheless, when once it
has been observed, belief in it is not based on inference and
reasoning, but merely upon its having been seen. In this way its
logical status differs from that of the theories which are proved
by its means.

In any science other than psychology the datum is primarily a
perception, in which only the sensational core is ultimately and
theoretically a datum, though some such accretions as turn the
sensation into a perception are practically unavoidable. But if
we postulate an ideal observer, he will be able to isolate the
sensation, and treat this alone as datum. There is, therefore, an
important sense in which we may say that, if we analyse as much
as we ought, our data, outside psychology, consist of sensations,
which include within themselves certain spatial and temporal
relations.

Applying this remark to physiology, we see that the nerves and
brain as physical objects are not truly data; they are to be
replaced, in the ideal structure of science, by the sensations
through which the physiologist is said to perceive them. The
passage from these sensations to nerves and brain as physical
objects belongs really to the initial stage in the theory of
physics, and ought to be placed in the reasoned part, not in the
part supposed to be observed. To say we see the nerves is like
saying we hear the nightingale; both are convenient but
inaccurate expressions. We hear a sound which we believe to be
causally connected with the nightingale, and we see a sight which
we believe to be causally connected with a nerve. But in each
case it is only the sensation that ought, in strictness, to be
called a datum. Now, sensations are certainly among the data of
psychology. Therefore all the data of the physical sciences are
also psychological data. It remains to inquire whether all the
data of psychology are also data of physical science, and
especially of physiology.

If we have been right in our analysis of mind, the ultimate data
of psychology are only sensations and images and their relations.
Beliefs, desires, volitions, and so on, appeared to us to be
complex phenomena consisting of sensations and images variously
interrelated. Thus (apart from certain relations) the occurrences
which seem most distinctively mental, and furthest removed from
physics, are, like physical objects, constructed or inferred, not
part of the original stock of data in the perfected science. From
both ends, therefore, the difference between physical and
psychological data is diminished. Is there ultimately no
difference, or do images remain as irreducibly and exclusively
psychological? In view of the causal definition of the difference
between images and sensations, this brings us to a new question,
namely: Are the causal laws of psychology different from those of
any other science, or are they really physiological?

Certain ambiguities must be removed before this question can be
adequately discussed.

First, there is the distinction between rough approximate laws
and such as appear to be precise and general. I shall return to
the former presently; it is the latter that I wish to discuss
now.

Matter, as defined at the end of Lecture V, is a logical fiction,
invented because it gives a convenient way of stating causal
laws. Except in cases of perfect regularity in appearances (of
which we can have no experience), the actual appearances of a
piece of matter are not members of that ideal system of regular
appearances which is defined as being the matter in question. But
the matter is. after all, inferred from its appearances, which
are used to VERIFY physical laws. Thus, in so far as physics is
an empirical and verifiable science, it must assume or prove that
the inference from appearances to matter is, in general,
legitimate, and it must be able to tell us, more or less, what
appearances to expect. It is through this question of
verifiability and empirical applicability to experience that we
are led to a theory of matter such as I advocate. From the
consideration of this question it results that physics, in so far
as it is an empirical science, not a logical phantasy, is
concerned with particulars of just the same sort as those which
psychology considers under the name of sensations. The causal
laws of physics, so interpreted, differ from those of psychology
only by the fact that they connect a particular with other
appearances in the same piece of matter, rather than with other
appearances in the same perspective. That is to say, they group
together particulars having the same "active" place, while
psychology groups together those having the same "passive" place.
Some particulars, such as images, have no "active" place, and
therefore belong exclusively to psychology.

We can now understand the distinction between physics and
psychology. The nerves and brain are matter: our visual
sensations when we look at them may be, and I think are, members
of the system constituting irregular appearances of this matter,
but are not the whole of the system. Psychology is concerned,
inter alia, with our sensations when we see a piece of matter, as
opposed to the matter which we see. Assuming, as we must, that
our sensations have physical causes, their causal laws are
nevertheless radically different from the laws of physics, since
the consideration of a single sensation requires the breaking up
of the group of which it is a member. When a sensation is used to
verify physics, it is used merely as a sign of a certain material
phenomenon, i.e. of a group of particulars of which it is a
member. But when it is studied by psychology, it is taken away
from that group and put into quite a different context, where it
causes images or voluntary movements. It is primarily this
different grouping that is characteristic of psychology as
opposed to all the physical sciences, including physiology; a
secondary difference is that images, which belong to psychology,
are not easily to be included among the aspects which constitute
a physical thing or piece of matter.

There remains, however, an important question, namely: Are mental
events causally dependent upon physical events in a sense in
which the converse dependence does not hold? Before we can
discuss the answer to this question, we must first be clear as to
what our question means.

When, given A, it is possible to infer B, but given B, it is not
possible to infer A, we say that B is dependent upon A in a sense
in which A is not dependent upon B. Stated in logical terms, this
amounts to saying that, when we know a many-one relation of A to
B, B is dependent upon A in respect of this relation. If the
relation is a causal law, we say that B is causally dependent
upon A. The illustration that chiefly concerns us is the system
of appearances of a physical object. We can, broadly speaking,
infer distant appearances from near ones, but not vice versa. All
men look alike when they are a mile away, hence when we see a man
a mile off we cannot tell what he will look like when he is only
a yard away. But when we see him a yard away, we can tell what he
will look like a mile away. Thus the nearer view gives us more
valuable information, and the distant view is causally dependent
upon it in a sense in which it is not causally dependent upon the
distant view.

It is this greater causal potency of the near appearance that
leads physics to state its causal laws in terms of that system of
regular appearances to which the nearest appearances increasingly
approximate, and that makes it value information derived from the
microscope or telescope. It is clear that our sensations,
considered as irregular appearances of physical objects, share
the causal dependence belonging to comparatively distant
appearances; therefore in our sensational life we are in causal
dependence upon physical laws.

This, however, is not the most important or interesting part of
our question. It is the causation of images that is the vital
problem. We have seen that they are subject to mnenic causation,
and that mnenic causation may be reducible to ordinary physical
causation in nervous tissue. This is the question upon which our
attitude must turn towards what may be called materialism. One
sense of materialism is the view that all mental phenomena are
causally dependent upon physical phenomena in the above-defined
sense of causal dependence. Whether this is the case or not, I do
not profess to know. The question seems to me the same as the
question whether mnemic causation is ultimate, which we
considered without deciding in Lecture IV. But I think the bulk
of the evidence points to the materialistic answer as the more
probable.

In considering the causal laws of psychology, the distinction
between rough generalizations and exact laws is important. There
are many rough generalizations in psychology, not only of the
sort by which we govern our ordinary behaviour to each other, but
also of a more nearly scientific kind. Habit and association
belong among such laws. I will give an illustration of the kind
of law that can be obtained. Suppose a person has frequently
experienced A and B in close temporal contiguity, an association
will be established, so that A, or an image of A, tends to cause
an image of B. The question arises: will the association work in
either direction, or only from the one which has occurred earlier
to the one which has occurred later? In an article by Mr.
Wohlgemuth, called "The Direction of Associations" ("British
Journal of Psychology," vol. v, part iv, March, 1913), it is
claimed to be proved by experiment that, in so far as motor
memory (i.e. memory of movements) is concerned, association works
only from earlier to later, while in visual and auditory memory
this is not the case, but the later of two neighbouring
experiences may recall the earlier as well as the earlier the
later. It is suggested that motor memory is physiological, while
visual and auditory memory are more truly psychological. But that
is not the point which concerns us in the illustration. The point
which concerns us is that a law of association, established by
purely psychological observation, is a purely psychological law,
and may serve as a sample of what is possible in the way of
discovering such laws. It is, however, still no more than a rough
generalization, a statistical average. It cannot tell us what
will result from a given cause on a given occasion. It is a law
of tendency, not a precise and invariable law such as those of
physics aim at being.

If we wish to pass from the law of habit, stated as a tendency or
average, to something more precise and invariable, we seem driven
to the nervous system. We can more or less guess how an
occurrence produces a change in the brain, and how its repetition
gradually produces something analogous to the channel of a river,
along which currents flow more easily than in neighbouring paths.
We can perceive that in this way, if we had more knowledge, the
tendency to habit through repetition might be replaced by a
precise account of the effect of each occurrence in bringing
about a modification of the sort from which habit would
ultimately result. It is such considerations that make students
of psychophysiology materialistic in their methods, whatever they
may be in their metaphysics. There are, of course, exceptions,
such as Professor J. S. Haldane,* who maintains that it is
theoretically impossible to obtain physiological explanations of
psychical phenomena, or physical explanations of physiological
phenomena. But I think the bulk of expert opinion, in practice,
is on the other side.

*See his book, "The New Physiology and Other Addresses" (Charles
Griffin & Co., 1919).

The question whether it is possible to obtain precise causal laws
in which the causes are psychological, not material, is one of
detailed investigation. I have done what I could to make clear
the nature of the question, but I do not believe that it is
possible as yet to answer it with any confidence. It seems to be
by no means an insoluble question, and we may hope that science
will be able to produce sufficient grounds for regarding one
answer as much more probable than the other. But for the moment I
do not see how we can come to a decision.

I think, however, on grounds of the theory of matter explained in
Lectures V and VII, that an ultimate scientific account of what
goes on in the world, if it were ascertainable, would resemble
psychology rather than physics in what we found to be the
decisive difference between them. I think, that is to say, that
such an account would not be content to speak, even formally, as
though matter, which is a logical fiction, were the ultimate
reality. I think that, if our scientific knowledge were adequate
to the task, which it neither is nor is likely to become, it
would exhibit the laws of correlation of the particulars
constituting a momentary condition of a material unit, and would
state the causal laws* of the world in terms of these
particulars, not in terms of matter. Causal laws so stated would,
I believe, be applicable to psychology and physics equally; the
science in which they were stated would succeed in achieving what
metaphysics has vainly attempted, namely a unified account of
what really happens, wholly true even if not the whole of truth,
and free from all convenient fictions or unwarrantable
assumptions of metaphysical entities. A causal law applicable to
particulars would count as a law of physics if it could be stated
in terms of those fictitious systems of regular appearances which
are matter; if this were not the case, it would count as a law of
psychology if one of the particulars were a sensation or an
image, i.e. were subject to mnemic causation. I believe that the
realization of the complexity of a material unit, and its
analysis into constituents analogous to sensations, is of the
utmost importance to philosophy, and vital for any understanding
of the relations between mind and matter, between our perceptions
and the world which they perceive. It is in this direction, I am
convinced, that we must look for the solution of many ancient
perplexities.

* In a perfected science, causal laws will take the form of
differential equations--or of finite-difference equations, if the
theory of quanta should prove correct.

It is probable that the whole science of mental occurrences,
especially where its initial definitions are concerned, could be
simplified by the development of the fundamental unifying science
in which the causal laws of particulars are sought, rather than
the causal laws of those systems of particulars that constitute
the material units of physics. This fundamental science would
cause physics to become derivative, in the sort of way in which
theories of the constitution of the atom make chemistry
derivative from physics; it would also cause psychology to appear
less singular and isolated among sciences. If we are right in
this, it is a wrong philosophy of matter which has caused many of
the difficulties in the philosophy of mind--difficulties which a
right philosophy of matter would cause to disappear.

The conclusions at which we have arrived may be summed up as
follows:

I. Physics and psychology are not distinguished by their
material. Mind and matter alike are logical constructions; the
particulars out of which they are constructed, or from which they
are inferred, have various relations, some of which are studied
by physics, others by psychology. Broadly speaking, physics group
particulars by their active places, psychology by their passive
places.

II. The two most essential characteristics of the causal laws
which would naturally be called psychological are SUBJECTIVITY
and MNEMIC CAUSATION; these are not unconnected, since the causal
unit in mnemic causation is the group of particulars having a
given passive place at a given time, and it is by this manner of
grouping that subjectivity is defined.

III. Habit, memory and thought are all developments of mnemic
causation. It is probable, though not certain, that mnemic
causation is derivative from ordinary physical causation in
nervous (and other) tissue.

IV. Consciousness is a complex and far from universal
characteristic of mental phenomena.

V. Mind is a matter of degree, chiefly exemplified in number and
complexity of habits.

VI. All our data, both in physics and psychology, are subject to
psychological causal laws; but physical causal laws, at least in
traditional physics, can only be stated in terms of matter, which
is both inferred and constructed, never a datum. In this respect
psychology is nearer to what actually exists.

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