The Analysis of Mind, Bertrand Russell [best desktop ebook reader .txt] 📗

IMPRESSIONS; and under this name I comprehend all our

sensations, passions and emotions, as they make their first

appearance in the soul. By IDEAS I mean the faint images of these

in thinking and reasoning.”

 

He next explains the difference between simple and complex ideas,

and explains that a complex idea may occur without any similar

complex impression. But as regards simple ideas, he states that

“every simple idea has a simple impression, which resembles it,

and every simple impression a correspondent idea.” He goes on to

enunciate the general principle “that all our simple ideas in

their first appearance are derived from simple impressions, which

are correspondent to them, and which they exactly represent”

(“Treatise of Human Nature,” Part I, Section I).

 

It is this fact, that images resemble antecedent sensations,

which enables us to call them images “of” this or that. For the

understanding of memory, and of knowledge generally, the

recognizable resemblance of images and sensations is of

fundamental importance.

 

There are difficulties in establishing Hume’s principles, and

doubts as to whether it is exactly true. Indeed, he himself

signalized an exception immediately after stating his maxim.

Nevertheless, it is impossible to doubt that in the main simple

images are copies of similar simple sensations which have

occurred earlier, and that the same is true of complex images in

all cases of memory as opposed to mere imagination. Our power of

acting with reference to what is sensibly absent is largely due

to this characteristic of images, although, as education

advances, images tend to be more and more replaced by words. We

shall have much to say in the next two lectures on the subject of

images as copies of sensations. What has been said now is merely

by way of reminder that this is their most notable

characteristic.

 

I am by no means confident that the distinction between images

and sensations is ultimately valid, and I should be glad to be

convinced that images can be reduced to sensations of a peculiar

kind. I think it is clear, however, that, at any rate in the case

of auditory and visual images, they do differ from ordinary

auditory and visual sensations, and therefore form a recognizable

class of occurrences, even if it should prove that they can be

regarded as a sub-class of sensations. This is all that is

necessary to validate the use of images to be made in the sequel.

 

LECTURE IX. MEMORY

 

Memory, which we are to consider to-day, introduces us to

knowledge in one of its forms. The analysis of knowledge will

occupy us until the end of the thirteenth lecture, and is the

most difficult part of our whole enterprise.

 

I do not myself believe that the analysis of knowledge can be

effected entirely by means of purely external observation, such

as behaviourists employ. I shall discuss this question in later

lectures. In the present lecture I shall attempt the analysis of

memory-knowledge, both as an introduction to the problem of

knowledge in general, and because memory, in some form, is

presupposed in almost all other knowledge. Sensation, we decided,

is not a form of knowledge. It might, however, have been expected

that we should begin our discussion of knowledge with PERCEPTION,

i.e. with that integral experience of things in the environment,

out of which sensation is extracted by psychological analysis.

What is called perception differs from sensation by the fact that

the sensational ingredients bring up habitual associates—images

and expectations of their usual correlates—all of which are

subjectively indistinguishable from the sensation. The FACT of

past experience is essential in producing this filling-out of

sensation, but not the RECOLLECTION of past experience. The

nonsensational elements in perception can be wholly explained as

the result of habit, produced by frequent correlations.

Perception, according to our definition in Lecture VII, is no

more a form of knowledge than sensation is, except in so far as

it involves expectations. The purely psychological problems which

it raises are not very difficult, though they have sometimes been

rendered artificially obscure by unwillingness to admit the

fallibility of the nonsensational elements of perception. On the

other hand, memory raises many difficult and very important

problems, which it is necessary to consider at the first possible

moment.

 

One reason for treating memory at this early stage is that it

seems to be involved in the fact that images are recognized as

“copies” of past sensible experience. In the preceding lecture I

alluded to Hume’s principle “that all our simple ideas in their

first appearance are derived from simple impressions, which are

correspondent to them, and which they exactly represent.” Whether

or not this principle is liable to exceptions, everyone would

agree that is has a broad measure of truth, though the word

“exactly” might seem an overstatement, and it might seem more

correct to say that ideas APPROXIMATELY represent impressions.

Such modifications of Hume’s principle, however, do not affect

the problem which I wish to present for your consideration,

namely: Why do we believe that images are, sometimes or always,

approximately or exactly, copies of sensations? What sort of

evidence is there? And what sort of evidence is logically

possible? The difficulty of this question arises through the fact

that the sensation which an image is supposed to copy is in the

past when the image exists, and can therefore only be known by

memory, while, on the other hand, memory of past sensations seems

only possible by means of present images. How, then, are we to

find any way of comparing the present image and the past

sensation? The problem is just as acute if we say that images

differ from their prototypes as if we say that they resemble

them; it is the very possibility of comparison that is hard to

understand.* We think we can know that they are alike or

different, but we cannot bring them together in one experience

and compare them. To deal with this problem, we must have a

theory of memory. In this way the whole status of images as

“copies” is bound up with the analysis of memory.

 

* How, for example, can we obtain such knowledge as the

following: “If we look at, say, a red nose and perceive it, and

after a little while ekphore, its memory-image, we note

immediately how unlike, in its likeness, this memory-image is to

the original perception” (A. Wohlgemuth, “On the Feelings and

their Neural Correlate with an Examination of the Nature of

Pain,” “Journal of Psychology,” vol. viii, part iv, June, 1917).

 

In investigating memory-beliefs, there are certain points which

must be borne in mind. In the first place, everything

constituting a memory-belief is happening now, not in that past

time to which the belief is said to refer. It is not logically

necessary to the existence of a memory-belief that the event

remembered should have occurred, or even that the past should

have existed at all. There is no logical impossibility in the

hypothesis that the world sprang into being five minutes ago,

exactly as it then was, with a population that “remembered” a

wholly unreal past. There is no logically necessary connection

between events at different times; therefore nothing that is

happening now or will happen in the future can disprove the

hypothesis that the world began five minutes ago. Hence the

occurrences which are CALLED knowledge of the past are logically

independent of the past; they are wholly analysable into present

contents, which might, theoretically, be just what they are even

if no past had existed.

 

I am not suggesting that the non-existence of the past should be

entertained as a serious hypothesis. Like all sceptical

hypotheses, it is logically tenable, but uninteresting. All that

I am doing is to use its logical tenability as a help in the

analysis of what occurs when we remember.

 

In the second place, images without beliefs are insufficient to

constitute memory; and habits are still more insufficient. The

behaviourist, who attempts to make psychology a record of

behaviour, has to trust his memory in making the record. “Habit”

is a concept involving the occurrence of similar events at

different times; if the behaviourist feels confident that there

is such a phenomenon as habit, that can only be because he trusts

his memory, when it assures him that there have been other times.

And the same applies to images. If we are to know as it is

supposed we do—that images are “copies,” accurate or inaccurate,

of past events, something more than the mere occurrence of images

must go to constitute this knowledge. For their mere occurrence,

by itself, would not suggest any connection with anything that

had happened before.

 

Can we constitute memory out of images together with suitable

beliefs? We may take it that memory-images, when they occur in

true memory, are (a) known to be copies, (b) sometimes known to

be imperfect copies (cf. footnote on previous page). How is it

possible to know that a memory-image is an imperfect copy,

without having a more accurate copy by which to replace it? This

would SEEM to suggest that we have a way of knowing the past

which is independent of images, by means of which we can

criticize image-memories. But I do not think such an inference is

warranted.

 

What results, formally, from our knowledge of the past through

images of which we recognize the inaccuracy, is that such images

must have two characteristics by which we can arrange them in two

series, of which one corresponds to the more or less remote

period in the past to which they refer, and the other to our

greater or less confidence in their accuracy. We will take the

second of these points first.

 

Our confidence or lack of confidence in the accuracy of a

memory-image must, in fundamental cases, be based upon a

characteristic of the image itself, since we cannot evoke the

past bodily and compare it with the present image. It might be

suggested that vagueness is the required characteristic, but I do

not think this is the case. We sometimes have images that are by

no means peculiarly vague, which yet we do not trust—for

example, under the influence of fatigue we may see a friend’s

face vividly and clearly, but horribly distorted. In such a case

we distrust our image in spite of its being unusually clear. I

think the characteristic by which we distinguish the images we

trust is the feeling of FAMILIARITY that accompanies them. Some

images, like some sensations, feel very familiar, while others

feel strange. Familiarity is a feeling capable of degrees. In an

image of a well-known face, for example, some parts may feel more

familiar than others; when this happens, we have more belief in

the accuracy of the familiar parts than in that of the unfamiliar

parts. I think it is by this means that we become critical of

images, not by some imageless memory with which we compare them.

I shall return to the consideration of familiarity shortly.

 

I come now to the other characteristic which memory-images must

have in order to account for our knowledge of the past. They must

have some characteristic which makes us regard them as referring

to more or less remote portions of the past. That is to say if we

suppose that A is the event remembered, B the remembering, and t

the interval of time between A and B, there must be some

characteristic of B which is capable of degrees, and which, in

accurately dated memories, varies as t varies. It may increase as

t increases, or diminish as t increases. The question which of

these occurs is not of any importance for the theoretic

serviceability of the characteristic in question.

 

In actual fact, there are doubtless various factors that concur

in giving us the feeling of greater or less remoteness in