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

found

in nature. Everything in nature is apparently in a state of

continuous change,* so that what we call one “event” turns out to

be really a process. If this event is to cause another event, the

two will have to be contiguous in time; for if there is any

interval between them, something may happen during that interval

to prevent the expected effect. Cause and effect, therefore, will

have to be temporally contiguous processes. It is difficult to

believe, at any rate where physical laws are concerned, that the

earlier part of the process which is the cause can make any

difference to the effect, so long as the later part of the

process which is the cause remains unchanged. Suppose, for

example, that a man dies of arsenic poisoning, we say that his

taking arsenic was the cause of death. But clearly the process by

which he acquired the arsenic is irrelevant: everything that

happened before he swallowed it may be ignored, since it cannot

alter the effect except in so far as it alters his condition at

the moment of taking the dose. But we may go further: swallowing

arsenic is not really the proximate cause of death, since a man

might be shot through the head immediately after taking the dose,

and then it would not be of arsenic that he would die. The

arsenic produces certain physiological changes, which take a

finite time before they end in death. The earlier parts of these

changes can be ruled out in the same way as we can rule out the

process by which the arsenic was acquired. Proceeding in this

way, we can shorten the process which we are calling the cause

more and more. Similarly we shall have to shorten the effect. It

may happen that immediately after the man’s death his body is

blown to pieces by a bomb. We cannot say what will happen after

the man’s death, through merely knowing that he has died as the

result of arsenic poisoning. Thus, if we are to take the cause as

one event and the effect as another, both must be shortened

indefinitely. The result is that we merely have, as the

embodiment of our causal law, a certain direction of change at

each moment. Hence we are brought to differential equations as

embodying causal laws. A physical law does not say “A will be

followed by B,” but tells us what acceleration a particle will

have under given circumstances, i.e. it tells us how the

particle’s motion is changing at each moment, not where the

particle will be at some future moment.

 

* The theory of quanta suggests that the continuity is only

apparent. If so, we shall be able theoretically to reach events

which are not processes. But in what is directly observable there

is still apparent continuity, which justifies the above remarks

for the prevent.

 

Laws embodied in differential equations may possibly be exact,

but cannot be known to be so. All that we can know empirically is

approximate and liable to exceptions; the exact laws that are

assumed in physics are known to be somewhere near the truth, but

are not known to be true just as they stand. The laws that we

actually know empirically have the form of the traditional causal

laws, except that they are not to be regarded as universal or

necessary. “Taking arsenic is followed by death” is a good

empirical generalization; it may have exceptions, but they will

be rare. As against the professedly exact laws of physics, such

empirical generalizations have the advantage that they deal with

observable phenomena. We cannot observe infinitesimals, whether

in time or space; we do not even know whether time and space are

infinitely divisible. Therefore rough empirical generalizations

have a definite place in science, in spite of not being exact of

universal. They are the data for more exact laws, and the grounds

for believing that they are USUALLY true are stronger than the

grounds for believing that the more exact laws are ALWAYS true.

 

Science starts, therefore, from generalizations of the form, “A

is usually followed by B.” This is the nearest approach that can

be made to a causal law of the traditional sort. It may happen in

any particular instance that A is ALWAYS followed by B, but we

cannot know this, since we cannot foresee all the perfectly

possible circumstances that might make the sequence fail, or know

that none of them will actually occur. If, however, we know of a

very large number of cases in which A is followed by B, and few

or none in which the sequence fails, we shall in PRACTICE be

justified in saying “A causes B,” provided we do not attach to

the notion of cause any of the metaphysical superstitions that

have gathered about the word.

 

There is another point, besides lack of universality and

necessity, which it is important to realize as regards causes in

the above sense, and that is the lack of uniqueness. It is

generally assumed that, given any event, there is some one

phenomenon which is THE cause of the event in question. This

seems to be a mere mistake. Cause, in the only sense in which it

can be practically applied, means “nearly invariable antecedent.”

We cannot in practice obtain an antecedent which is QUITE

invariable, for this would require us to take account of the

whole universe, since something not taken account of may prevent

the expected effect. We cannot distinguish, among nearly

invariable antecedents, one as THE cause, and the others as

merely its concomitants: the attempt to do this depends upon a

notion of cause which is derived from will, and will (as we shall

see later) is not at all the sort of thing that it is generally

supposed to be, nor is there any reason to think that in the

physical world there is anything even remotely analogous to what

will is supposed to be. If we could find one antecedent, and only

one, that was QUITE invariable, we could call that one THE cause

without introducing any notion derived from mistaken ideas about

will. But in fact we cannot find any antecedent that we know to

be quite invariable, and we can find many that are nearly so. For

example, men leave a factory for dinner when the hooter sounds at

twelve o’clock. You may say the hooter is THE cause of their

leaving. But innumerable other hooters in other factories, which

also always sound at twelve o’clock, have just as good a right to

be called the cause. Thus every event has many nearly invariable

antecedents, and therefore many antecedents which may be called

its cause.

 

The laws of traditional physics, in the form in which they deal

with movements of matter or electricity, have an apparent

simplicity which somewhat conceals the empirical character of

what they assert. A piece of matter, as it is known empirically,

is not a single existing thing, but a system of existing things.

When several people simultaneously see the same table, they all

see something different; therefore “the” table, which they are

supposed all to see, must be either a hypothesis or a

construction. “The” table is to be neutral as between different

observers: it does not favour the aspect seen by one man at the

expense of that seen by another. It was natural, though to my

mind mistaken, to regard the “real” table as the common cause of

all the appearances which the table presents (as we say) to

different observers. But why should we suppose that there is some

one common cause of all these appearances? As we have just seen,

the notion of “cause” is not so reliable as to allow us to infer

the existence of something that, by its very nature, can never be

observed.

 

Instead of looking for an impartial source, we can secure

neutrality by the equal representation of all parties. Instead of

supposing that there is some unknown cause, the “real” table,

behind the different sensations of those who are said to be

looking at the table, we may take the whole set of these

sensations (together possibly with certain other particulars) as

actually BEING the table. That is to say, the table which is

neutral as between different observers (actual and possible) is

the set of all those particulars which would naturally be called

“aspects” of the table from different points of view. (This is a

first approximation, modified later.)

 

It may be said: If there is no single existent which is the

source of all these “aspects,” how are they collected together?

The answer is simple: Just as they would be if there were such a

single existent. The supposed “real” table underlying its

appearances is, in any case, not itself perceived, but inferred,

and the question whether such-and-such a particular is an

“aspect” of this table is only to be settled by the connection of

the particular in question with the one or more particulars by

which the table is defined. That is to say, even if we assume a

“real” table, the particulars which are its aspects have to be

collected together by their relations to each other, not to it,

since it is merely inferred from them. We have only, therefore,

to notice how they are collected together, and we can then keep

the collection without assuming any “real” table as distinct from

the collection. When different people see what they call the same

table, they see things which are not exactly the same, owing to

difference of point of view, but which are sufficiently alike to

be described in the same words, so long as no great accuracy or

minuteness is sought. These closely similar particulars are

collected together by their similarity primarily and, more

correctly, by the fact that they are related to each other

approximately according to the laws of perspective and of

reflection and diffraction of light. I suggest, as a first

approximation, that these particulars, together with such

correlated others as are unperceived, jointly ARE the table; and

that a similar definition applies to all physical objects.*

 

*See “Our Knowledge of the External World” (Allen & Unwin),

chaps. iii and iv.

 

In order to eliminate the reference to our perceptions, which

introduces an irrelevant psychological suggestion, I will take a

different illustration, namely, stellar photography. A

photographic plate exposed on a clear night reproduces the

appearance of the portion of the sky concerned, with more or

fewer stars according to the power of the telescope that is being

used. Each separate star which is photographed produces its

separate effect on the plate, just as it would upon ourselves if

we were looking at the sky. If we assume, as science normally

does, the continuity of physical processes, we are forced to

conclude that, at the place where the plate is, and at all places

between it and a star which it photographs, SOMETHING is

happening which is specially connected with that star. In the

days when the aether was less in doubt, we should have said that

what was happening was a certain kind of transverse vibration in

the aether. But it is not necessary or desirable to be so

explicit: all that we need say is that SOMETHING happens which is

specially connected with the star in question. It must be

something specially connected with that star, since that star

produces its own special effect upon the plate. Whatever it is

must be the end of a process which starts from the star and

radiates outwards, partly on general grounds of continuity,

partly to account for the fact that light is transmitted with a

certain definite velocity. We thus arrive at the conclusion that,

if a certain star is visible at a certain place, or could be

photographed by a sufficiently sensitive plate at that place,

something