No More Learning

Plurality of causes, however, results only from
conceiving the effect vaguely and narrowly and the cause precisely and
widely. Many antecedents may "cause" a man's death, because his death
is vague and narrow. But if we adopt the opposite course, taking as
the "cause" the drinking of a dose of arsenic, and as the "effect" the
whole state of the world five minutes later, we shall have plurality
of effects instead of plurality of causes. Thus the supposed lack of
symmetry between "cause" and "effect" is illusory.

(4) "A cause cannot operate when it has ceased to exist, because what
has ceased to exist is nothing. " This is a common maxim, and a still
more common unexpressed prejudice. It has, I fancy, a good deal to do
with the attractiveness of Bergson's "_duree_": since the past has
effects now, it must still exist in some sense. The mistake in this
maxim consists in the supposition that causes "operate" at all. A
volition "operates" when what it wills takes place; but nothing can
operate except a volition. The belief that causes "operate" results
from assimilating them, consciously or unconsciously, to volitions. We
have already seen that, if there are causes at all, they must be
separated by a finite interval of time from their effects, and thus
cause their effects after they have ceased to exist.

It may be objected to the above definition of a volition "operating"
that it only operates when it "causes" what it wills, not when it
merely happens to be followed by what it wills. This certainly
represents the usual view of what is meant by a volition "operating,"
but as it involves the very view of causation which we are engaged in
combating, it is not open to us as a definition. We may say that a
volition "operates" when there is some law in virtue of which a
similar volition in rather similar circumstances will usually be
followed by what it wills. But this is a vague conception, and
introduces ideas which we have not yet considered. What is chiefly
important to notice is that the usual notion of "operating" is not
open to us if we reject, as I contend that we should, the usual notion
of causation.

(5) "A cause cannot operate except where it is. " This maxim is very
widespread; it was urged against Newton, and has remained a source of
prejudice against "action at a distance. " In philosophy it has led to
a denial of transient action, and thence to monism or Leibnizian
monadism. Like the analogous maxim concerning temporal contiguity, it
rests upon the assumption that causes "operate," i. e. that they are in
some obscure way analogous to volitions. And, as in the case of
temporal contiguity, the inferences drawn from this maxim are wholly
groundless.

I return now to the question, What law or laws can be found to take
the place of the supposed law of causality?

First, without passing beyond such uniformities of sequence as are
contemplated by the traditional law, we may admit that, if any such
sequence has been observed in a great many cases, and has never been
found to fail, there is an inductive probability that it will be found
to hold in future cases. If stones have hitherto been found to break
windows, it is probable that they will continue to do so. This, of
course, assumes the inductive principle, of which the truth may
reasonably be questioned; but as this principle is not our present
concern, I shall in this discussion treat it as indubitable. We may
then say, in the case of any such frequently observed sequence, that
the earlier event is the _cause_ and the later event the _effect_.

Several considerations, however, make such special sequences very
different from the traditional relation of cause and effect. In the
first place, the sequence, in any hitherto unobserved instance, is no
more than probable, whereas the relation of cause and effect was
supposed to be necessary. I do not mean by this merely that we are not
sure of having discovered a true case of cause and effect; I mean
that, even when we have a case of cause and effect in our present
sense, all that is meant is that on grounds of observation, it is
probable that when one occurs the other will also occur. Thus in our
present sense, A may be the cause of B even if there actually are
cases where B does not follow A. Striking a match will be the cause of
its igniting, in spite of the fact that some matches are damp and fail
to ignite.

In the second place, it will not be assumed that _every_ event has
some antecedent which is its cause in this sense; we shall only
believe in causal sequences where we find them, without any
presumption that they always are to be found.

In the third place, _any_ case of sufficiently frequent sequence will
be causal in our present sense; for example, we shall not refuse to
say that night is the cause of day. Our repugnance to saying this
arises from the ease with which we can imagine the sequence to fail,
but owing to the fact that cause and effect must be separated by a
finite interval of time, _any_ such sequence _might_ fail through the
interposition of other circumstances in the interval. Mill, discussing
this instance of night and day, says:--

"It is necessary to our using the word cause, that we should believe
not only that the antecedent always _has_ been followed by the
consequent, but that as long as the present constitution of things
endures, it always _will_ be so. "[39]

In this sense, we shall have to give up the hope of finding causal
laws such as Mill contemplated; any causal sequence which we have
observed may at any moment be falsified without a falsification of any
laws of the kind that the more advanced sciences aim at establishing.

In the fourth place, such laws of probable sequence, though useful in
daily life and in the infancy of a science, tend to be displaced by
quite different laws as soon as a science is successful. The law of
gravitation will illustrate what occurs in any advanced science. In
the motions of mutually gravitating bodies, there is nothing that can
be called a cause, and nothing that can be called an effect; there is
merely a formula. Certain differential equations can be found, which
hold at every instant for every particle of the system, and which,
given the configuration and velocities at one instant, or the
configurations at two instants, render the configuration at any other
earlier or later instant theoretically calculable. That is to say, the
configuration at any instant is a function of that instant and the
configurations at two given instants. This statement holds throughout
physics, and not only in the special case of gravitation. But there is
nothing that could be properly called "cause" and nothing that could
be properly called "effect" in such a system.

No doubt the reason why the old "law of causality" has so long
continued to pervade the books of philosophers is simply that the idea
of a function is unfamiliar to most of them, and therefore they seek
an unduly simplified statement. There is no question of repetitions of
the "same" cause producing the "same" effect; it is not in any
sameness of causes and effects that the constancy of scientific law
consists, but in sameness of relations. And even "sameness of
relations" is too simple a phrase; "sameness of differential
equations" is the only correct phrase. It is impossible to state this
accurately in non-mathematical language; the nearest approach would be
as follows: "There is a constant relation between the state of the
universe at any instant and the rate of change in the rate at which
any part of the universe is changing at that instant, and this
relation is many-one, i. e. such that the rate of change in the rate of
change is determinate when the state of the universe is given. " If the
"law of causality" is to be something actually discoverable in the
practice of science, the above proposition has a better right to the
name than any "law of causality" to be found in the books of
philosophers.

In regard to the above principle, several observations must be made--

(1) No one can pretend that the above principle is _a priori_ or
self-evident or a "necessity of thought. " Nor is it, in any sense, a
premiss of science: it is an empirical generalisation from a number of
laws which are themselves empirical generalisations.

(2) The law makes no difference between past and future: the future
"determines" the past in exactly the same sense in which the past
"determines" the future. The word "determine," here, has a purely
logical significance: a certain number of variables "determine"
another variable if that other variable is a function of them.

(3) The law will not be empirically verifiable unless the course of
events within some sufficiently small volume will be approximately
the same in any two states of the universe which only differ in regard
to what is at a considerable distance from the small volume in
question. For example, motions of planets in the solar system must be
approximately the same however the fixed stars may be distributed,
provided that all the fixed stars are very much farther from the sun
than the planets are. If gravitation varied directly as the distance,
so that the most remote stars made the most difference to the motions
of the planets, the world might be just as regular and just as much
subject to mathematical laws as it is at present, but we could never
discover the fact.

(4) Although the old "law of causality" is not assumed by science,
something which we may call the "uniformity of nature" is assumed, or
rather is accepted on inductive grounds. The uniformity of nature does
not assert the trivial principle "same cause, same effect," but the
principle of the permanence of laws. That is to say, when a law
exhibiting, e. g. an acceleration as a function of the configuration
has been found to hold throughout the observable past, it is expected
that it will continue to hold in the future, or that, if it does not
itself hold, there is some other law, agreeing with the supposed law
as regards the past, which will hold for the future. The ground of
this principle is simply the inductive ground that it has been found
to be true in very many instances; hence the principle cannot be
considered certain, but only probable to a degree which cannot be
accurately estimated.

The uniformity of nature, in the above sense, although it is assumed
in the practice of science, must not, in its generality, be regarded
as a kind of major premiss, without which all scientific reasoning
would be in error. The assumption that _all_ laws of nature are
permanent has, of course, less probability than the assumption that
this or that particular law is permanent; and the assumption that a
particular law is permanent for all time has less probability than the
assumption that it will be valid up to such and such a date. Science,
in any given case, will assume what the case requires, but no more. In
constructing the _Nautical Almanac_ for 1915 it will assume that the
law of gravitation will remain true up to the end of that year; but it
will make no assumption as to 1916 until it comes to the next volume
of the almanac. This procedure is, of course, dictated by the fact
that the uniformity of nature is not known _a priori_, but is an
empirical generalisation, like "all men are mortal. " In all such
cases, it is better to argue immediately from the given particular
instances to the new instance, than to argue by way of a major
premiss; the conclusion is only probable in either case, but acquires
a higher probability by the former method than by the latter.

In all science we have to distinguish two sorts of laws: first, those
that are empirically verifiable but probably only approximate;
secondly, those that are not verifiable, but may be exact. The law of
gravitation, for example, in its applications to the solar system, is
only empirically verifiable when it is assumed that matter outside the
solar system may be ignored for such purposes; we believe this to be
only approximately true, but we cannot empirically verify the law of
universal gravitation which we believe to be exact. This point is very
important in connection with what we may call "relatively isolated
systems. " These may be defined as follows:--

A system relatively isolated during a given period is one which,
within some assignable margin of error, will behave in the same way
throughout that period, however the rest of the universe may be
constituted.

A system may be called "practically isolated" during a given period
if, although there _might_ be states of the rest of the universe which
would produce more than the assigned margin of error, there is reason
to believe that such states do not in fact occur.

Strictly speaking, we ought to specify the respect in which the system
is relatively isolated. For example, the earth is relatively isolated
as regards falling bodies, but not as regards tides; it is
_practically_ isolated as regards economic phenomena, although, if
Jevons' sunspot theory of commercial crises had been true, it would
not have been even practically isolated in this respect.

It will be observed that we cannot prove in advance that a system is
isolated. This will be inferred from the observed fact that
approximate uniformities can be stated for this system alone. If the
complete laws for the whole universe were known, the isolation of a
system could be deduced from them; assuming, for example, the law of
universal gravitation, the practical isolation of the solar system in
this respect can be deduced by the help of the fact that there is very
little matter in its neighbourhood. But it should be observed that
isolated systems are only important as providing a possibility of
_discovering_ scientific laws; they have no theoretical importance in
the finished structure of a science.

The case where one event A is said to "cause" another event B, which
philosophers take as fundamental, is really only the most simplified
instance of a practically isolated system. It may happen that, as a
result of general scientific laws, whenever A occurs throughout a
certain period, it is followed by B; in that case, A and B form a
system which is practically isolated throughout that period. It is,
however, to be regarded as a piece of good fortune if this occurs; it
will always be due to special circumstances, and would not have been
true if the rest of the universe had been different though subject to
the same laws.

The essential function which causality has been supposed to perform is
the possibility of inferring the future from the past, or, more
generally, events at any time from events at certain assigned times.
Any system in which such inference is possible may be called a
"deterministic" system. We may define a deterministic system as
follows:--

A system is said to be "deterministic" when, given certain data,
[Math: e_{1}, e_{2}, . . . , e_{n}, at times t_{1}, t_{2}, . . . ,
t_{n}] respectively, concerning this system, if [Math: E_{t}] is
the state of the system at any time _t_, there is a functional
relation of the form

[Math: E_{t} = f (e_{1}, t_{1}, e_{2}, t_{2}, . . . , e_{n}, t_{n}, t)]. (A)

The system will be "deterministic throughout a given period" if
_t_, in the above formula, may be any time within that period,
though outside that period the formula may be no longer true. If
the universe, as a whole, is such a system, determinism is true of
the universe; if not, not. A system which is part of a
deterministic system I shall call "determined"; one which is not
part of any such system I shall call "capricious. "

The events [Math: e_{1}, e_{2}, . . . , e_{n}] I shall call "determinants"
of the system. It is to be observed that a system which has one set of
determinants will in general have many. In the case of the motions of
the planets, for example, the configurations of the solar system at any
two given times will be determinants.

We may take another illustration from the hypothesis of
psycho-physical parallelism. Let us assume, for the purposes of this
illustration, that to a given state of brain a given state of mind
always corresponds, and vice versa, i. e. that there is a one-one
relation between them, so that each is a function of the other. We may
also assume, what is practically certain, that to a given state of a
certain brain a given state of the whole material universe
corresponds, since it is highly improbable that a given brain is ever
twice in exactly the same state. Hence there will be a one-one
relation between the state of a given person's mind and the state of
the whole material universe. It follows that, if _n_ states of the
material universe are determinants of the material universe, then _n_
states of a given man's mind are determinants of the whole material
and mental universe--assuming, that is to say, that psycho-physical
parallelism is true.

The above illustration is important in connection with a certain
confusion which seems to have beset those who have philosophised on
the relation of mind and matter. It is often thought that, if the
state of the mind is determinate when the state of the brain is given,
and if the material world forms a deterministic system, then mind is
"subject" to matter in some sense in which matter is not "subject" to
mind. But if the state of the brain is also determinate when the state
of the mind is given, it must be exactly as true to regard matter as
subject to mind as it would be to regard mind as subject to matter. We
could, theoretically, work out the history of mind without ever
mentioning matter, and then, at the end, deduce that matter must
meanwhile have gone through the corresponding history. It is true that
if the relation of brain to mind were many-one, not one-one, there
would be a one-sided dependence of mind on brain, while conversely, if
the relation were one-many, as Bergson supposes, there would be a
one-aided dependence of brain on mind. But the dependence involved is,
in any case, only logical; it does not mean that we shall be
compelled to do things we desire not to do, which is what people
instinctively imagine it to mean.

As another illustration we may take the case of mechanism and
teleology. A system may be defined as "mechanical" when it has a set
of determinants that are purely material, such as the positions of
certain pieces of matter at certain times. It is an open question
whether the world of mind and matter, as we know it, is a mechanical
system or not; let us suppose, for the sake of argument, that it is a
mechanical system. This supposition--so I contend--throws no light
whatever on the question whether the universe is or is not a
"teleological" system. It is difficult to define accurately what is
meant by a "teleological" system, but the argument is not much
affected by the particular definition we adopt. Broadly, a
teleological system is one in which purposes are realised, i. e. in
which certain desires--those that are deeper or nobler or more
fundamental or more universal or what not--are followed by their
realisation. Now the fact--if it be a fact--that the universe is
mechanical has no bearing whatever on the question whether it is
teleological in the above sense. There might be a mechanical system in
which all wishes were realised, and there might be one in which all
wishes were thwarted. The question whether, or how far, our actual
world is teleological, cannot, therefore, be settled by proving that
it is mechanical, and the desire that it should be teleological is no
ground for wishing it to be not mechanical.

There is, in all these questions, a very great difficulty in avoiding
confusion between what we can infer and what is in fact determined.
Let us consider, for a moment, the various senses in which the future
may be "determined. " There is one sense--and a very important one--in
which it is determined quite independently of scientific laws, namely,
the sense that it will be what it will be. We all regard the past as
determined simply by the fact that it has happened; but for the
accident that memory works backward and not forward, we should regard
the future as equally determined by the fact that it will happen.
"But," we are told, "you cannot alter the past, while you can to some
extent alter the future. " This view seems to me to rest upon just
those errors in regard to causation which it has been my object to
remove. You cannot make the past other than it was--true, but this is
a mere application of the law of contradiction. If you already know
what the past was, obviously it is useless to wish it different. But
also you cannot make the future other than it will be; this again is
an application of the law of contradiction. And if you happen to know
the future--e. g. in the case of a forthcoming eclipse--it is just as
useless to wish it different as to wish the past different. "But," it
will be rejoined, "our wishes can _cause_ the future, sometimes, to be
different from what it would be if they did not exist, and they can
have no such effect upon the past. " This, again, is a mere tautology.
An effect being _defined_ as something subsequent to its cause,
obviously we can have no _effect_ upon the past. But that does not
mean that the past would not have been different if our present wishes
had been different. Obviously, our present wishes are conditioned by
the past, and therefore could not have been different unless the past
had been different; therefore, if our present wishes were different,
the past would be different. Of course, the past cannot be different
from what it was, but no more can our present wishes be different from
what they are; this again is merely the law of contradiction. The
facts seem to be merely (1) that wishing generally depends upon
ignorance, and is therefore commoner in regard to the future than in
regard to the past; (2) that where a wish concerns the future, it and
its realisation very often form a "practically independent system,"
i. e. many wishes regarding the future are realised. But there seems no
doubt that the main difference in our feelings arises from the
accidental fact that the past but not the future can be known by
memory.

Although the sense of "determined" in which the future is determined
by the mere fact that it will be what it will be is sufficient (at
least so it seems to me) to refute some opponents of determinism,
notably M. Bergson and the pragmatists, yet it is not what most people
have in mind when they speak of the future as determined. What they
have in mind is a formula by means of which the future can be
exhibited, and at least theoretically calculated, as a function of the
past. But at this point we meet with a great difficulty, which besets
what has been said above about deterministic systems, as well as what
is said by others.

If formulae of any degree of complexity, however great, are admitted,
it would seem that any system, whose state at a given moment is a
function of certain measurable quantities, must be a deterministic
system. Let us consider, in illustration, a single material particle,
whose co-ordinates at time _t_ are [Math: x_{t}, y_{t}, z_{t}]. Then,
however, the particle moves, there must be, theoretically, functions
[Math: f_{1}, f_{2}, f_{3}], such that

[Math: x_{t} = f_{t}(t), y_{t} = f_{2}(t), z_{t} = f_{3}(t). ]

It follows that, theoretically, the whole state of the material
universe at time _t_ must be capable of being exhibited as a function
of _t_. Hence our universe will be deterministic in the sense defined
above. But if this be true, no information is conveyed about the
universe in stating that it is deterministic. It is true that the
formulae involved may be of strictly infinite complexity, and therefore
not practically capable of being written down or apprehended. But
except from the point of view of our knowledge, this might seem to be
a detail: in itself, if the above considerations are sound, the
material universe _must_ be deterministic, _must_ be subject to laws.

This, however, is plainly not what was intended. The difference
between this view and the view intended may be seen as follows. Given
some formula which fits the facts hitherto--say the law of
gravitation--there will be an infinite number of other formulae, not
empirically distinguishable from it in the past, but diverging from it
more and more in the future. Hence, even assuming that there are
persistent laws, we shall have no reason for assuming that the law of
the inverse square will hold in future; it may be some other hitherto
indistinguishable law that will hold. We cannot say that _every_ law
which has held hitherto must hold in the future, because past facts
which obey one law will also obey others, hitherto indistinguishable
but diverging in future. Hence there must, at every moment, be laws
hitherto unbroken which are now broken for the first time. What
science does, in fact, is to select the _simplest_ formula that will
fit the facts. But this, quite obviously, is merely a methodological
precept, not a law of Nature. If the simplest formula ceases, after a
time, to be applicable, the simplest formula that remains applicable
is selected, and science has no sense that an axiom has been
falsified. We are thus left with the brute fact that, in many
departments of science, quite simple laws have hitherto been found to
hold. This fact cannot be regarded as having any _a priori_ ground,
nor can it be used to support inductively the opinion that the same
laws will continue; for at every moment laws hitherto true are being
falsified, though in the advanced sciences these laws are less simple
than those that have remained true. Moreover it would be fallacious to
argue inductively from the state of the advanced sciences to the
future state of the others, for it may well be that the advanced
sciences are advanced simply because, hitherto, their subject-matter
has obeyed simple and easily ascertainable laws, while the
subject-matter of other sciences has not done so.

The difficulty we have been considering seems to be met partly, if not
wholly, by the principle that the _time_ must not enter explicitly
into our formulae. All mechanical laws exhibit acceleration as a
function of configuration, not of configuration and time jointly; and
this principle of the irrelevance of the time may be extended to all
scientific laws. In fact we might interpret the "uniformity of nature"
as meaning just this, that no scientific law involves the time as an
argument, unless, of course, it is given in an integrated form, in
which case _lapse_ of time, though not absolute time, may appear in
our formulae. Whether this consideration suffices to overcome our
difficulty completely, I do not know; but in any case it does much to
diminish it.

It will serve to illustrate what has been said if we apply it to the
question of free will.

(1) Determinism in regard to the will is the doctrine that our
volitions belong to some deterministic system, i. e. are "determined"
in the sense defined above. Whether this doctrine is true or false, is
a mere question of fact; no _a priori_ considerations (if our previous
discussions have been correct) can exist on either side. On the one
hand, there is no _a priori_ category of causality, but merely certain
observed uniformities. As a matter of fact, there are observed
uniformities in regard to volitions; thus there is some empirical
evidence that volitions are determined. But it would be very rash to
maintain that the evidence is overwhelming, and it is quite possible
that some volitions, as well as some other things, are not determined,
except in the sense in which we found that everything must be
determined.

(2) But, on the other hand, the subjective sense of freedom, sometimes
alleged against determinism, has no bearing on the question whatever.
The view that it has a bearing rests upon the belief that causes
compel their effects, or that nature enforces obedience to its laws as
governments do. These are mere anthropomorphic superstitions, due to
assimilation of causes with volitions and of natural laws with human
edicts. We feel that our will is not compelled, but that only means
that it is not other than we choose it to be. It is one of the
demerits of the traditional theory of causality that it has created an
artificial opposition between determinism and the freedom of which we
are introspectively conscious.

(3) Besides the general question whether volitions are determined,
there is the further question whether they are _mechanically_
determined, i. e. whether they are part of what was above defined as a
mechanical system. This is the question whether they form part of a
system with purely material determinants, i. e. whether there are laws
which, given certain material data, make all volitions functions of
those data. Here again, there is empirical evidence up to a point, but
it is not conclusive in regard to all volitions.
It is important to
observe, however that even if volitions are part of a mechanical
system, this by no means implies any supremacy of matter over mind. It
may well be that the same system which is susceptible of material
determinants is also susceptible of mental determinants; thus a
mechanical system may be determined by sets of volitions, as well as
by sets of material facts. It would seem, therefore, that the reasons
which make people dislike the view that volitions are mechanically
determined are fallacious.

(4) The notion of _necessity_, which is often associated with
determinism, is a confused notion not legitimately deducible from
determinism. Three meanings are commonly confounded when necessity is
spoken of:--

(? ) An _action_ is necessary when it will be performed however much
the agent may wish to do otherwise. Determinism does not imply that
actions are necessary in this sense.

(? ) A _propositional function_ is necessary when all its values are
true. This sense is not relevant to our present discussion.

(? ) A _proposition_ is necessary with respect to a given constituent
when it is the value, with that constituent as argument, of a
necessary propositional function, in other words, when it remains true
however that constituent may be varied. In this sense, in a
deterministic system, the connection of a volition with its
determinants is necessary, if the time at which the determinants occur
be taken as the constituent to be varied, the time-interval between
the determinants and the volition being kept constant. But this sense
of necessity is purely logical, and has no emotional importance.

We may now sum up our discussion of causality. We found first that the
law of causality, as usually stated by philosophers, is false, and is
not employed in science. We then considered the nature of scientific
laws, and found that, instead of stating that one event A is always
followed by another event B, they stated functional relations between
certain events at certain times, which we called determinants, and
other events at earlier or later times or at the same time. We were
unable to find any _a priori_ category involved: the existence of
scientific laws appeared as a purely empirical fact, not necessarily
universal, except in a trivial and scientifically useless form. We
found that a system with one set of determinants may very likely have
other sets of a quite different kind, that, for example, a
mechanically determined system may also be teleologically or
volitionally determined. Finally we considered the problem of free
will: here we found that the reasons for supposing volitions to be
determined are strong but not conclusive, and we decided that even if
volitions are mechanically determined, that is no reason for denying
freedom in the sense revealed by introspection, or for supposing that
mechanical events are not determined by volitions. The problem of free
will _versus_ determinism is therefore, if we were right, mainly
illusory, but in part not yet capable of being decisively solved.

FOOTNOTES:

[35] A propositional function is an expression containing a variable,
or undetermined constituent, and becoming a proposition as soon as a
definite value is assigned to the variable. Examples are: "A is A,"
"_x_ is a number. " The variable is called the _argument_ of the
function.

[36] _Logic_, Bk. III, Chap. V, ? 2.

[37] _Time and Free Will_, p. 199.

[38] _Time and Free Will. _ p. 202.

[39] _Loc. cit. _, ? 6




X

KNOWLEDGE BY ACQUAINTANCE AND KNOWLEDGE BY DESCRIPTION


The object of the following paper is to consider what it is that we
know in cases where we know propositions about "the so-and-so" without
knowing who or what the so-and-so is. For example, I know that the
candidate who gets most votes will be elected, though I do not know
who is the candidate who will get most votes. The problem I wish to
consider is: What do we know in these cases, where the subject is
merely described? I have considered this problem elsewhere[40] from a
purely logical point of view; but in what follows I wish to consider
the question in relation to theory of knowledge as well as in relation
to logic, and in view of the above-mentioned logical discussions, I
shall in this paper make the logical portion as brief as possible.

In order to make clear the antithesis between "acquaintance" and
"description," I shall first of all try to explain what I mean by
"acquaintance. " I say that I am _acquainted_ with an object when I
have a direct cognitive relation to that object, i. e. when I am
directly aware of the object itself. When I speak of a cognitive
relation here, I do not mean the sort of relation which constitutes
judgment, but the sort which constitutes presentation. In fact, I
think the relation of subject and object which I call acquaintance is
simply the converse of the relation of object and subject which
constitutes presentation. That is, to say that S has acquaintance with
O is essentially the same thing as to say that O is presented to S.
But the associations and natural extensions of the word _acquaintance_
are different from those of the word _presentation_. To begin with, as
in most cognitive words, it is natural to say that I am acquainted
with an object even at moments when it is not actually before my mind,
provided it has been before my mind, and will be again whenever
occasion arises. This is the same sense in which I am said to know
that 2+2=4 even when I am thinking of something else. In the second
place, the word _acquaintance_ is designed to emphasise, more than the
word _presentation_, the relational character of the fact with which
we are concerned. There is, to my mind, a danger that, in speaking of
presentation, we may so emphasise the object as to lose sight of the
subject. The result of this is either to lead to the view that there
is no subject, whence we arrive at materialism; or to lead to the view
that what is presented is part of the subject, whence we arrive at
idealism, and should arrive at solipsism but for the most desperate
contortions. Now I wish to preserve the dualism of subject and object
in my terminology, because this dualism seems to me a fundamental fact
concerning cognition. Hence I prefer the word _acquaintance_ because
it emphasises the need of a subject which is acquainted.

When we ask what are the kinds of objects with which we are
acquainted, the first and most obvious example is _sense-data_. When I
see a colour or hear a noise, I have direct acquaintance with the
colour or the noise. The sense-datum with which I am acquainted in
these cases is generally, if not always, complex. This is
particularly obvious in the case of sight. I do not mean, of course,
merely that the supposed physical object is complex, but that the
direct sensible object is complex and contains parts with spatial
relations. Whether it is possible to be aware of a complex without
being aware of its constituents is not an easy question, but on the
whole it would seem that there is no reason why it should not be
possible. This question arises in an acute form in connection with
self-consciousness, which we must now briefly consider.

In introspection, we seem to be immediately aware of varying
complexes, consisting of objects in various cognitive and conative
relations to ourselves. When I see the sun, it often happens that I
am aware of my seeing the sun, in addition to being aware of the sun;
and when I desire food, it often happens that I am aware of my desire
for food. But it is hard to discover any state of mind in which I am
aware of myself alone, as opposed to a complex of which I am a
constituent. The question of the nature of self-consciousness is too
large and too slightly connected with our subject, to be argued at
length here. It is difficult, but probably not impossible, to account
for plain facts if we assume that we do not have acquaintance with
ourselves. It is plain that we are not only _acquainted_ with the
complex "Self-acquainted-with-A," but we also _know_ the proposition
"I am acquainted with A. " Now here the complex has been analysed, and
if "I" does not stand for something which is a direct object of
acquaintance, we shall have to suppose that "I" is something known by
description. If we wished to maintain the view that there is no
acquaintance with Self, we might argue as follows: We are acquainted
with _acquaintance_, and we know that it is a relation. Also we are
acquainted with a complex in which we perceive that acquaintance is
the relating relation. Hence we know that this complex must have a
constituent which is that which is acquainted, i. e. must have a
subject-term as well as an object-term. This subject-term we define
as "I. " Thus "I" means "the subject-term in awarenesses of which _I_
am aware. " But as a definition this cannot be regarded as a happy
effort. It would seem necessary, therefore, either to suppose that I
am acquainted with myself, and that "I," therefore, requires no
definition, being merely the proper name of a certain object, or to
find some other analysis of self-consciousness. Thus self-consciousness
cannot be regarded as throwing light on the question whether we can
know a complex without knowing its constituents. This question,
however, is not important for our present purposes, and I shall
therefore not discuss it further.

The awarenesses we have considered so far have all been awarenesses of
particular existents, and might all in a large sense be called
sense-data. For, from the point of view of theory of knowledge,
introspective knowledge is exactly on a level with knowledge derived
from sight or hearing. But, in addition to awareness of the above kind
of objects, which may be called awareness of _particulars_; we have
also (though not quite in the same sense) what may be called awareness
of _universals_. Awareness of universals is called _conceiving_, and a
universal of which we are aware is called a _concept_. Not only are we
aware of particular yellows, but if we have seen a sufficient number
of yellows and have sufficient intelligence, we are aware of the
universal _yellow_; this universal is the subject in such judgments as
"yellow differs from blue" or "yellow resembles blue less than green
does. " And the universal yellow is the predicate in such judgments as
"this is yellow," where "this" is a particular sense-datum. And
universal relations, too, are objects of awarenesses; up and down,
before and after, resemblance, desire, awareness itself, and so on,
would seem to be all of them objects of which we can be aware.

In regard to relations, it might be urged that we are never aware of
the universal relation itself, but only of complexes in which it is a
constituent. For example, it may be said that we do not know directly
such a relation as _before_, though we understand such a proposition
as "this is before that," and may be directly aware of such a complex
as "this being before that. " This view, however, is difficult to
reconcile with the fact that we often know propositions in which the
relation is the subject, or in which the relata are not definite given
objects, but "anything. " For example, we know that if one thing is
before another, and the other before a third, then the first is before
the third; and here the things concerned are not definite things, but
"anything. " It is hard to see how we could know such a fact about
"before" unless we were acquainted with "before," and not merely with
actual particular cases of one given object being before another given
object. And more directly: A judgment such as "this is before that,"
where this judgment is derived from awareness of a complex,
constitutes an analysis, and we should not understand the analysis if
we were not acquainted with the meaning of the terms employed. Thus we
must suppose that we are acquainted with the meaning of "before," and
not merely with instances of it.

There are thus at least two sorts of objects of which we are aware,
namely, particulars and universals. Among particulars I include all
existents, and all complexes of which one or more constituents are
existents, such as this-before-that, this-above-that,
the-yellowness-of-this. Among universals I include all objects of
which no particular is a constituent. Thus the disjunction
"universal-particular" includes all objects. We might also call it the
disjunction "abstract-concrete. " It is not quite parallel with the
opposition "concept-percept," because things remembered or imagined
belong with particulars, but can hardly be called percepts. (On the
other hand, universals with which we are acquainted may be identified
with concepts. )

It will be seen that among the objects with which we are acquainted
are not included physical objects (as opposed to sense-data), nor
other people's minds. These things are known to us by what I call
"knowledge by description," which we must now consider.

By a "description" I mean any phrase of the form "a so-and-so" or "the
so-and-so. " A phrase of the form "a so-and-so" I shall call an
"ambiguous" description; a phrase of the form "the so-and-so" (in the
singular) I shall call a "definite" description. Thus "a man" is an
ambiguous description, and "the man with the iron mask" is a definite
description. There are various problems connected with ambiguous
descriptions, but I pass them by, since they do not directly concern
the matter I wish to discuss. What I wish to discuss is the nature of
our knowledge concerning objects in cases where we know that there is
an object answering to a definite description, though we are not
_acquainted_ with any such object. This is a matter which is concerned
exclusively with _definite_ descriptions. I shall, therefore, in the
sequel, speak simply of "descriptions" when I mean "definite
descriptions. " Thus a description will mean any phrase of the form
"the so-and-so" in the singular.

I shall say that an object is "known by description" when we know that
it is "_the_ so-and-so," i. e. when we know that there is one object,
and no more, having a certain property; and it will generally be
implied that we do not have knowledge of the same object by
acquaintance. We know that the man with the iron mask existed, and
many propositions are known about him; but we do not know who he was.
We know that the candidate who gets most votes will be elected, and in
this case we are very likely also acquainted (in the only sense in
which one can be acquainted with some one else) with the man who is,
in fact, the candidate who will get most votes, but we do not know
which of the candidates he is, i. e. we do not know any proposition of
the form "A is the candidate who will get most votes" where A is one
of the candidates by name. We shall say that we have "_merely_
descriptive knowledge" of the so-and-so when, although we know that
the so-and-so exists, and although we may possibly be acquainted with
the object which is, in fact, the so-and-so, yet we do not know any
proposition "_a_ is the so-and-so," where _a_ is something with which
we are acquainted.

When we say "the so-and-so exists," we mean that there is just one
object which is the so-and-so. The proposition "_a_ is the so-and-so"
means that _a_ has the property so-and-so, and nothing else has. "Sir
Joseph Larmor is the Unionist candidate" means "Sir Joseph Larmor is a
Unionist candidate, and no one else is. " "The Unionist candidate
exists" means "some one is a Unionist candidate, and no one else is. "
Thus, when we are acquainted with an object which we know to be the
so-and-so, we know that the so-and-so exists but we may know that the
so-and-so exists when we are not acquainted with any object which we
know to be the so-and-so, and even when we are not acquainted with any
object which, in fact, is the so-and-so.

Common words, even proper names, are usually really descriptions. That
is to say, the thought in the mind of a person using a proper name
correctly can generally only be expressed explicitly if we replace the
proper name by a description. Moreover, the description required to
express the thought will vary for different people, or for the same
person at different times. The only thing constant (so long as the
name is rightly used) is the object to which the name applies. But so
long as this remains constant, the particular description involved
usually makes no difference to the truth or falsehood of the
proposition in which the name appears.

Let us take some illustrations. Suppose some statement made about
Bismarck. Assuming that there is such a thing as direct acquaintance
with oneself, Bismarck himself might have used his name directly to
designate the particular person with whom he was acquainted. In this
case, if he made a judgment about himself, he himself might be a
constituent of the judgment. Here the proper name has the direct use
which it always wishes to have, as simply standing for a certain
object, and not for a description of the object. But if a person who
knew Bismarck made a judgment about him, the case is different. What
this person was acquainted with were certain sense-data which he
connected (rightly, we will suppose) with Bismarck's body. His body as
a physical object, and still more his mind, were only known as the
body and the mind connected with these sense-data. That is, they were
known by description. It is, of course, very much a matter of chance
which characteristics of a man's appearance will come into a friend's
mind when he thinks of him; thus the description actually in the
friend's mind is accidental. The essential point is that he knows that
the various descriptions all apply to the same entity, in spite of
not being acquainted with the entity in question.

When we, who did not know Bismarck, make a judgment about him, the
description in our minds will probably be some more or less vague mass
of historical knowledge--far more, in most cases, than is required to
identify him. But, for the sake of illustration, let us assume that we
think of him as "the first Chancellor of the German Empire. " Here all
the words are abstract except "German. " The word "German" will again
have different meanings for different people. To some it will recall
travels in Germany, to some the look of Germany on the map, and so on.
But if we are to obtain a description which we know to be applicable,
we shall be compelled, at some point, to bring in a reference to a
particular with which we are acquainted. Such reference is involved in
any mention of past, present, and future (as opposed to definite
dates), or of here and there, or of what others have told us. Thus it
would seem that, in some way or other, a description known to be
applicable to a particular must involve some reference to a particular
with which we are acquainted, if our knowledge about the thing
described is not to be merely what follows logically from the
description. For example, "the most long-lived of men" is a
description which must apply to some man, but we can make no judgments
concerning this man which involve knowledge about him beyond what the
description gives. If, however, we say, "the first Chancellor of the
German Empire was an astute diplomatist," we can only be assured of
the truth of our judgment in virtue of something with which we are
acquainted--usually a testimony heard or read. Considered
psychologically, apart from the information we convey to others, apart
from the fact about the actual Bismarck, which gives importance to
our judgment, the thought we really have contains the one or more
particulars involved, and otherwise consists wholly of concepts. All
names of places--London, England, Europe, the earth, the Solar
System--similarly involve, when used, descriptions which start from
some one or more particulars with which we are acquainted. I suspect
that even the Universe, as considered by metaphysics, involves such a
connection with particulars. In logic, on the contrary, where we are
concerned not merely with what does exist, but with whatever might or
could exist or be, no reference to actual particulars is involved.

It would seem that, when we make a statement about something only
known by description, we often _intend_ to make our statement, not in
the form involving the description, but about the actual thing
described. That is to say, when we say anything about Bismarck, we
should like, if we could, to make the judgment which Bismarck alone
can make, namely, the judgment of which he himself is a constituent.
In this we are necessarily defeated, since the actual Bismarck is
unknown to us. But we know that there is an object B called Bismarck,
and that B was an astute diplomatist. We can thus _describe_ the
proposition we should like to affirm, namely, "B was an astute
diplomatist," where B is the object which was Bismarck. What enables
us to communicate in spite of the varying descriptions we employ is
that we know there is a true proposition concerning the actual
Bismarck, and that, however we may vary the description (so long as
the description is correct), the proposition described is still the
same. This proposition, which is described and is known to be true, is
what interests us; but we are not acquainted with the proposition
itself, and do not know _it_, though we know it is true.

It will be seen that there are various stages in the removal from
acquaintance with particulars: there is Bismarck to people who knew
him, Bismarck to those who only know of him through history, the man
with the iron mask, the longest-lived of men. These are progressively
further removed from acquaintance with particulars, and there is a
similar hierarchy in the region of universals. Many universals, like
many particulars, are only known to us by description. But here, as in
the case of particulars, knowledge concerning what is known by
description is ultimately reducible to knowledge concerning what is
known by acquaintance.

The fundamental epistemological principle in the analysis of
propositions containing descriptions is this: _Every proposition which
we can understand must be composed wholly of constituents with which
we are acquainted. _ From what has been said already, it will be plain
why I advocate this principle, and how I propose to meet the case of
propositions which at first sight contravene it. Let us begin with the
reasons for supposing the principle true.

The chief reason for supposing the principle true is that it seems
scarcely possible to believe that we can make a judgment or entertain
a supposition without knowing what it is that we are judging or
supposing about. If we make a judgment about (say) Julius Caesar, it is
plain that the actual person who was Julius Caesar is not a constituent
of the judgment. But before going further, it may be well to explain
what I mean when I say that this or that is a constituent of a
judgment, or of a proposition which we understand. To begin with
judgments: a judgment, as an occurrence, I take to be a relation of a
mind to several entities, namely, the entities which compose what is
judged. If, e. g. I judge that A loves B, the judgment as an event
consists in the existence, at a certain moment, of a specific
four-term relation, called _judging_, between me and A and love and B.
That is to say, at the time when I judge, there is a certain complex
whose terms are myself and A and love and B, and whose relating
relation is _judging_. My reasons for this view have been set forth
elsewhere,[41] and I shall not repeat them here. Assuming this view of
judgment, the constituents of the judgment are simply the constituents
of the complex which is the judgment. Thus, in the above case, the
constituents are myself and A and love and B and judging. But myself
and judging are constituents shared by all my judgments; thus the
_distinctive_ constituents of the particular judgment in question are
A and love and B. Coming now to what is meant by "understanding a
proposition," I should say that there is another relation possible
between me and A and love and B, which is called my _supposing_ that A
loves B. [42] When we can _suppose_ that A loves B, we "understand the
proposition" _A loves B_. Thus we often understand a proposition in
cases where we have not enough knowledge to make a judgment.
Supposing, like judging, is a many-term relation, of which a mind is
one term. The other terms of the relation are called the constituents
of the proposition supposed. Thus the principle which I enunciated may
be re-stated as follows: _Whenever a relation of supposing or judging
occurs, the terms to which the supposing or judging mind is related by
the relation of supposing or judging must be terms with which the mind
in question is acquainted. _ This is merely to say that we cannot make
a judgment or a supposition without knowing what it is that we are
making our judgment or supposition about. It seems to me that the
truth of this principle is evident as soon as the principle is
understood; I shall, therefore, in what follows, assume the principle,
and use it as a guide in analysing judgments that contain
descriptions.

Returning now to Julius Caesar, I assume that it will be admitted that
he himself is not a constituent of any judgment which I can make. But
at this point it is necessary to examine the view that judgments are
composed of something called "ideas," and that it is the "idea" of
Julius Caesar that is a constituent of my judgment. I believe the
plausibility of this view rests upon a failure to form a right theory
of descriptions. We may mean by my "idea" of Julius Caesar the things
that I know about him, e. g. that he conquered Gaul, was assassinated
on the Ides of March, and is a plague to schoolboys. Now I am
admitting, and indeed contending, that in order to discover what is
actually in my mind when I judge about Julius Caesar, we must
substitute for the proper name a description made up of some of the
things I know about him. (A description which will often serve to
express my thought is "the man whose name was _Julius Caesar_. " For
whatever else I may have forgotten about him, it is plain that when I
mention him I have not forgotten that that was his name. ) But although
I think the theory that judgments consist of ideas may have been
suggested in some such way, yet I think the theory itself is
fundamentally mistaken. The view seems to be that there is some
mental existent which may be called the "idea" of something outside
the mind of the person who has the idea, and that, since judgment is a
mental event, its constituents must be constituents of the mind of the
person judging. But in this view ideas become a veil between us and
outside things--we never really, in knowledge, attain to the things we
are supposed to be knowing about, but only to the ideas of those
things. The relation of mind, idea, and object, on this view, is
utterly obscure, and, so far as I can see, nothing discoverable by
inspection warrants the intrusion of the idea between the mind and the
object.