THEIR HISTORICAL BACKGROUND
48. THE DOCTRINE OF REPRESENTATIVE PERCEPTION.--We have seen in Chapter
II that it seems to the plain man abundantly evident that he really is
surrounded by material things and that he directly perceives such
things. This has always been the opinion of the plain man and it seems
probable that it always will be. It is only when he begins to reflect
upon things and upon his knowledge of them that it occurs to him to
call it in question.
Very early in the history of speculative thought it occurred to men,
however, to ask how it is that we know things, and whether we are sure
we do know them. The problems of reflection started into life, and
various solutions were suggested. To tell over the whole list would
take us far afield, and we need not, for the purpose we have in view,
go back farther than Descartes, with whom philosophy took a relatively
new start, and may be said to have become, in spirit and method, at
least, modern.
I have said (section 31) that Descartes (1596-1650) was fairly well
acquainted with the functioning of the nervous system, and has much to
say of the messages which pass along the nerves to the brain. The same
sort of reasoning that leads the modern psychologist to maintain that
we know only so much of the external world as is reflected in our
sensations led him to maintain that the mind is directly aware of the
ideas through which an external world is represented, but can know the
world itself only indirectly and through these ideas.
Descartes was put to sore straits to prove the existence of an external
world, when he had once thus placed it at one remove from us. If we
accept his doctrine, we seem to be shut up within the circle of our
ideas, and can find no door that will lead us to a world outside. The
question will keep coming back: How do we _know_ that, corresponding to
our ideas, there are material things, if we have never perceived, in
any single instance, a material thing? And the doubt here suggested
may be reinforced by the reflection that the very expression "a
material thing" ought to be meaningless to a man who, having never had
experience of one, is compelled to represent it by the aid of something
so different from it as ideas are supposed to be. Can material things
really be to such a creature anything more than some complex of ideas?
The difficulties presented by any philosophical doctrine are not always
evident at once. Descartes made no scruple of accepting the existence
of an external world, and his example has been followed by a very large
number of those who agree with his initial assumption that the mind
knows immediately only its own ideas.
Preëminent among such we must regard John Locke, the English
philosopher (1632-1704), whose classic work, "An Essay concerning Human
Understanding," should not be wholly unknown to any one who pretends to
an interest in the English literature.
Admirably does Locke represent the position of what very many have
regarded as the prudent and sensible man,--the man who recognizes that
ideas are not external things, and that things must be known through
ideas, and yet holds on to the existence of a material world which we
assuredly know.
He recognizes, it is true, that some one may find a possible opening
for the expression of a doubt, but he regards the doubt as gratuitous;
"I think nobody can, in earnest, be so skeptical as to be uncertain of
the existence of those things which he sees and feels." As we have
seen (section 12), he meets the doubt with a jest.
Nevertheless, those who read with attention Locke's admirably clear
pages must notice that he does not succeed in really setting to rest
the doubt that has suggested itself. It becomes clear that Locke felt
so sure of the existence of the external world because he now and then
slipped into the inconsistent doctrine that he perceived it
immediately, and not merely through his ideas. Are those things "which
he sees and feels" _external_ things? Does he see and feel them
directly, or must he infer from his ideas that he sees and feels them?
If the latter, why may one not still doubt? Evidently the appeal is to
a direct experience of material things, and Locke has forgotten that he
must be a Lockian.
"I have often remarked, in many instances," writes Descartes, "that
there is a great difference between an object and its idea." How could
the man possibly have remarked this, when he had never in his life
perceived the object corresponding to any idea, but had been altogether
shut up to ideas? "Thus I see, whilst I write this," says Locke,[1] "I
can change the appearance of the paper, and by designing the letters
tell beforehand what new idea it shall exhibit the very next moment, by
barely drawing my pen over it, which will neither appear (let me fancy
as much as I will), if my hand stands still, or though I move my pen,
if my eyes be shut; nor, when those characters are once made on the
paper, can I choose afterward but see them as they are; that is, have
the ideas of such letters as I have made. Whence it is manifest, that
they are not barely the sport and play of my own imagination, when I
find that the characters that were made at the pleasure of my own
thought do not obey them; nor yet cease to be, whenever I shall fancy
it; but continue to affect the senses constantly and regularly,
according to the figures I made them."
Locke is as bad as Descartes. Evidently he regards himself as able to
turn to the external world and perceive the relation that things hold
to ideas. Such an inconsistency may escape the writer who has been
guilty of it, but it is not likely to escape the notice of all those
who come after him. Some one is sure to draw the consequences of a
doctrine more rigorously, and to come to conclusions, it may be, very
unpalatable to the man who propounded the doctrine in the first
instance.
The type of doctrine represented by Descartes and Locke is that of
_Representative Perception_. It holds that we know real external
things only through their mental representatives. It has also been
called _Hypothetical Realism_, because it accepts the existence of a
real world, but bases our knowledge of it upon an inference from our
sensations or ideas.
49. THE STEP TO IDEALISM.--The admirable clearness with which Locke
writes makes it the easier for his reader to detect the untenability of
his position. He uses simple language, and he never takes refuge in
vague and ambiguous phrases. When he tells us that the mind is wholly
shut up to its ideas, and then later assumes that it is not shut up to
its ideas, but can perceive external things, we see plainly that there
must be a blunder somewhere.
George Berkeley (1684-1753), Bishop of Cloyne, followed out more
rigorously the consequences to be deduced from the assumption that all
our direct knowledge is of ideas; and in a youthful work of the highest
genius entitled "The Principles of Human Knowledge," he maintained that
there is no material world at all.
When we examine with care the objects of sense, the "things" which
present themselves to us, he argues, we find that they resolve
themselves into sensations, or "ideas of sense." What can we mean by
the word "apple," if we do not mean the group of experiences in which
alone an apple is presented to us? The word is nothing else than a
name for this group as a group. Take away the color, the hardness, the
odor, the taste; what have we left? And color, hardness, odor, taste,
and anything else that may be referred to any object as a quality, can
exist, he claims, only in a perceiving mind; for such things are
nothing else than sensations, and how can there be an unperceived
sensation?
The things which we perceive, then, he calls complexes of ideas. Have
we any reason to believe that these ideas, which exist in the mind, are
to be accepted as representatives of things of a different kind, which
are not mental at all? Not a shadow of a reason, says Berkeley; there
is simply no basis for inference at all, and we cannot even make clear
what it is that we are setting out to infer under the name of matter.
We need not, therefore, grieve over the loss of the material world, for
we have suffered no loss; one cannot lose what one has never had.
Thus, the objects of human knowledge, the only things of which it means
anything to speak, are: (1) Ideas of Sense; (2) Ideas of Memory and
Imagination; (3) The Passions and Operations of the Mind; and (4) The
Self that perceives all These.
From Locke's position to that of Berkeley was a bold step, and it was
much criticised, as well it might be. It was felt then, as it has been
felt by many down to our own time, that, when we discard an external
world distinct from our ideas, and admit only the world revealed in our
ideas, we really do lose.
It is legitimate to criticise Berkeley, but it is not legitimate to
misunderstand him; and yet the history of his doctrine may almost be
called a chronicle of misconceptions. It has been assumed that he drew
no distinction between real things and imaginary things, that he made
the world no better than a dream, etc. Arbuthnot, Swift, and a host of
the greater and lesser lights in literature, from his time to ours,
have made merry over the supposed unrealities in the midst of which the
Berkeleian must live.
But it should be remembered that Berkeley tried hard to do full justice
to the world of things in which we actually find ourselves; not a
hypothetical, inferred, unperceived world, but the world of the things
we actually perceive. He distinguished carefully between what is real
and what is merely imaginary, though he called both "ideas"; and he
recognized something like a system of nature. And, by the argument
from analogy which we have already examined (section 41), he inferred
the existence of other finite minds and of a Divine Mind.
But just as John Locke had not completely thought out the consequences
which might be deduced from his own doctrines, so Berkeley left, in his
turn, an opening for a successor. It was possible for that acutest of
analysts, David Hume (1711-1776), to treat him somewhat as he had
treated Locke.
Among the objects of human knowledge Berkeley had included the _self_
that perceives things. He never succeeded in making at all clear what
he meant by this object; but he regarded it as a substance, and
believed it to be a cause of changes in ideas, and quite different in
its nature from all the ideas attributed to it. But Hume maintained
that when he tried to get a good look at this self, to catch it, so to
speak, and to hold it up to inspection, he could not find anything
whatever save perceptions, memories, and other things of that kind.
The self is, he said, "but a bundle or collection of different
perceptions which succeed each other with inconceivable rapidity, and
are in a perpetual flux and movement."
As for the objects of sense, our own bodies, the chairs upon which we
sit, the tables at which we write, and all the rest--these, argues
Hume, we are impelled by nature to think of as existing continuously,
but we have no evidence whatever to prove that they do thus exist. Are
not the objects of sense, after all, only sensations or impressions?
Do we not experience these sensations or impressions interruptedly?
Who sees or feels a table continuously day after day? If the table is
but a name for the experiences in question, if we have no right to
infer material things behind and distinct from such experiences, are we
not forced to conclude that the existence of the things that we see and
feel is an interrupted one?
Hume certainly succeeded in raising more questions than he succeeded in
answering. We are compelled to admire the wonderful clearness and
simplicity of his style, and the acuteness of his intellect, in every
chapter. But we cannot help feeling that he does injustice to the
world in which we live, even when we cannot quite see what is wrong.
Does it not seem certain to science and to common sense that there is
an order of nature in some sense independent of our perceptions, so
that objects may be assumed to exist whether we do or do not perceive
them?
When we read Hume we have a sense that we are robbed of our real
external world; and his account of the mind makes us feel as a badly
tied sheaf of wheat may be conceived to feel--in danger of falling
apart at any moment. Berkeley we unhesitatingly call an _Idealist_,
but whether we shall apply the name to Hume depends upon the extension
we are willing to give to it. His world is a world of what we may
broadly call _ideas_; but the tendencies of his philosophy have led
some to call it a _Skepticism_.
50. THE REVOLT OF "COMMON SENSE."--Hume's reasonings were too important
to be ignored, and his conclusions too unpalatable to satisfy those who
came after him. It seemed necessary to seek a way of escape out of
this world of mere ideas, which appeared to be so unsatisfactory a
world. One of the most famous of such attempts was that made by the
Scotchman Thomas Reid (1710-1796).
At one time Reid regarded himself as the disciple of Berkeley, but the
consequences which Hume deduced from the principles laid down by the
former led Reid to feel that he must build upon some wholly different
foundation. He came to the conclusion that the line of philosophers
from Descartes to Hume had made one capital error in assuming "that
nothing is perceived but what is in the mind that perceives it."
Once admit, says Reid, that the mind perceives nothing save ideas, and
we must also admit that it is impossible to prove the existence either
of an external world or of a mind different from "a bundle of
perceptions." Hence, Reid maintains that we perceive--not infer, but
perceive--_things_ external to the mind. He writes:[2]--
"Let a man press his hand against the table--_he feels it hard_. But
what is the meaning of this? The meaning undoubtedly is, that he hath
a certain feeling of touch, from which he concludes, without any
reasoning, or comparing ideas, that there is something external really
existing, whose parts stick so firmly together that they cannot be
displaced without considerable force.
"There is here a feeling, and a conclusion drawn from it, or some way
suggested by it. In order to compare these, we must view them
separately, and then consider by what tie they are connected, and
wherein they resemble one another. The hardness of the table is the
conclusion, the feeling is the medium by which we are led to that
conclusion. Let a man attend distinctly to this medium, and to the
conclusion, and he will perceive them to be as unlike as any two things
in nature. The one is a sensation of the mind, which can have no
existence but in a sentient being; nor can it exist one moment longer
than it is felt; the other is in the table, and we conclude, without
any difficulty, that it was in the table before it was felt, and
continues after the feeling is over. The one implies no kind of
extension, nor parts, nor cohesion; the other implies all these. Both,
indeed, admit of degrees, and the feeling, beyond a certain degree, is
a species of pain; but adamantine hardness does not imply the least
pain.
"And as the feeling hath no similitude to hardness, so neither can our
reason perceive the least tie or connection between them; nor will the
logician ever be able to show a reason why we should conclude hardness
from this feeling, rather than softness, or any other quality
whatsoever. But, in reality, all mankind are led by their constitution
to conclude hardness from this feeling."
It is well worth while to read this extract several times, and to ask
oneself what Reid meant to say, and what he actually said. He is
objecting, be it remembered, to the doctrine that the mind perceives
immediately only its own ideas or sensations and must infer all else.
His contention is that we _perceive_ external things.
Does he say this? He says that we have feelings of touch _from which
we conclude_ that there is something external; that there is a feeling,
"_and a conclusion drawn from it, or some way suggested by it_;" that
"the hardness of the table is the _conclusion_, and the feeling is the
_medium_ by which we are _led to the conclusion_."
Could Descartes or Locke have more plainly supported the doctrine of
representative perception? How could Reid imagine he was combatting
that doctrine when he wrote thus? The point in which he differs from
them is this: he maintains that we draw the conclusion in question
without any reasoning, and, indeed, in the absence of any conceivable
reason why we should draw it. We do it instinctively; we are led by
the constitution of our nature.
In effect Reid says to us: When you lay your hand on the table, you
have a sensation, it is true, but you also know the table is hard. How
do you know it? I cannot tell you; you simply know it, and cannot help
knowing it; and that is the end of the matter.
Reid's doctrine was not without its effect upon other philosophers.
Among them we must place Sir William Hamilton (1788-1856), whose
writings had no little influence upon British philosophy in the last
half of the last century.
Hamilton complained that Reid did not succeed in being a very good
_Natural Realist_, and that he slipped unconsciously into the position
he was concerned to condemn. Sir William tried to eliminate this
error, but the careful reader of his works will find to his amusement
that this learned author gets his feet upon the same slippery descent.
And much the same thing may be said of the doctrine of Herbert Spencer
(1820-1903), who claims that, when we have a sensation, we know
directly that there is an external thing, and then manages to sublimate
that external thing into an Unknowable, which we not only do not know
directly, but even do not know at all.
All of these men were anxious to avoid what they regarded as the perils
of Idealism, and yet they seem quite unable to retain a foothold upon
the position which they consider the safer one.
Reid called his doctrine the philosophy of "Common Sense," and he
thought he was coming back from the subtleties of the metaphysicians to
the standpoint of the plain man. That he should fall into difficulties
and inconsistencies is by no means surprising. As we have seen
(section 12), the thought of the plain man is far from clear. He
certainly believes that we perceive an external world of things, and
the inconsistent way in which Descartes and Locke appeal from ideas to
the things themselves does not strike him as unnatural. Why should not
a man test his ideas by turning to things and comparing the former with
the latter? On the other hand, he knows that to perceive things we
must have sense organs and sensations, and he cannot quarrel with the
psychologists for saying that we know things only in so far as they are
revealed to us through our sensations. How does he reconcile these two
positions? He does not reconcile them. He accepts them as they stand.
Reid and various other philosophers have tried to come back to "Common
Sense" and to stay there. Now, it is a good position to come back to
for the purpose of starting out again. The experience of the plain
man, the truths which he recognizes as truths, these are not things to
be despised. Many a man whose mind has been, as Berkeley expresses it,
"debauched by learning," has gotten away from them to his detriment,
and has said very unreasonable things. But "Common Sense" cannot be
the ultimate refuge of the philosopher; it can only serve him as
material for investigation. The scholar whose thought is as vague and
inconsistent as that of the plain man has little profit in the fact
that the apparatus of his learning has made it possible for him to be
ponderously and unintelligibly vague and inconsistent.
Hence, we may have the utmost sympathy with Reid's protest against the
doctrine of representative perception, and we may, nevertheless,
complain that he has done little to explain how it is that we directly
know external things and yet cannot be said to know things except in so
far as we have sensations or ideas.
51. THE CRITICAL PHILOSOPHY.--The German philosopher, Immanuel Kant
(1724-1804), was moved, by the skeptical conclusions to which Hume's
philosophy seemed to lead, to seek a way of escape, somewhat as Reid
was. But he did not take refuge in "Common Sense"; he developed an
ingenious doctrine which has had an enormous influence in the
philosophical world, and has given rise to a Kantian literature of such
proportions that no man can hope to read all of it, even if he devotes
his life to it. In Germany and out of it, it has for a hundred years
and more simply rained books, pamphlets, and articles on Kant and his
philosophy, some of them good, many of them far from clear and far from
original. Hundreds of German university students have taken Kant as
the subject of the dissertation by which they hoped to win the degree
of Doctor of Philosophy;--I was lately offered two hundred and
seventy-four such dissertations in one bunch;--and no student is
supposed to have even a moderate knowledge of philosophy who has not an
acquaintance with that famous work, the "Critique of Pure Reason."
It is to be expected from the outset that, where so many have found so
much to say, there should reign abundant differences of opinion. There
are differences of opinion touching the interpretation of Kant, and
touching the criticisms which may be made upon, and the development
which should be given to, his doctrine. It is, of course, impossible
to go into all these things here; and I shall do no more than indicate,
in untechnical language and in briefest outline, what he offers us in
place of the philosophy of Hume.
Kant did not try to refute, as did Reid, the doctrine, urged by
Descartes and by his successors, that all those things which the mind
directly perceives are to be regarded as complexes of ideas. On the
contrary, he accepted it, and he has made the words "phenomenon" and
"noumenon" household words in philosophy.
The world which seems to be spread out before us in space and time is,
he tells us, a world of things _as they are revealed to our senses and
our intelligence_; it is a world of manifestations, of phenomena. What
things-in-themselves are like we have no means of knowing; we know only
things as they appear to us. We may, to be sure, talk of a something
distinct from phenomena, a something not revealed to the senses, but
thought of, a _noumenon_; but we should not forget that this is a
negative conception; there is nothing in our experience that can give
it a filling, for our experience is only of phenomena. The reader will
find an unmistakable echo of this doctrine in Herbert Spencer's
doctrine of the "Unknowable" and its "manifestations."
Now, Berkeley had called all the things we immediately perceive
_ideas_. As we have seen, he distinguished between "ideas of sense"
and "ideas of memory and imagination." Hume preferred to give to these
two classes different names--he called the first _impressions_ and the
second _ideas_.
The associations of the word "impression" are not to be mistaken.
Locke had taught that between ideas in the memory and genuine
sensations there is the difference that the latter are due to the
"brisk acting" of objects without us. Objects impress us, and we have
sensations or impressions. To be sure, Hume, after employing the word
"impression," goes on to argue that we have no evidence that there are
external objects, which cause impressions. But he retains the word
"impression," nevertheless, and his use of it perceptibly colors his
thought.
In Kant's distinction between phenomena and noumena we have the lineal
descendant of the old distinction between the circle of our ideas and
the something outside of them that causes them and of which they are
supposed to give information. Hume said we have no reason to believe
such a thing exists, but are impelled by our nature to believe in it.
Kant is not so much concerned to prove the nonexistence of noumena,
things-in-themselves, as he is to prove that the very conception is an
empty one. His reasonings seem to result in the conclusion that we can
make no intelligible statement about things so cut off from our
experience as noumena are supposed to be; and one would imagine that he
would have felt impelled to go on to the frank declaration that we have
no reason to believe in noumena at all, and had better throw away
altogether so meaningless and useless a notion. But he was a
conservative creature, and he did not go quite so far.
So far there is little choice between Kant and Hume. Certainly the
former does not appear to have rehabilitated the external world which
had suffered from the assaults of his predecessors. What important
difference is there between his doctrine and that of the man whose
skeptical tendencies he wished to combat?
The difference is this: Descartes and Locke had accounted for our
knowledge of things by maintaining that things act upon us, and make an
impression or sensation--that their action, so to speak, begets ideas.
This is a very ancient doctrine as well as a very modern one; it is the
doctrine that most men find reasonable even before they devote
themselves to the study of philosophy. The totality of such
impressions received from the external world, they are accustomed to
regard as our _experience_ of external things; and they are inclined to
think that any knowledge of external things not founded upon experience
can hardly deserve the name of knowledge.
Now, Hume, when he cast doubt upon the existence of external things,
did not, as I have said above, divest himself of the suggestions of the
word "impression." He insists strenuously that all our knowledge is
founded upon experience; and he holds that no experience can give us
knowledge that is necessary and universal. We know things as they are
revealed to us in our experience; but who can guarantee that we may not
have new experiences of a quite different kind, and which flatly
contradict the notions which we have so far attained of what is
possible and impossible, true and untrue.
It is here that Kant takes issue with Hume. A survey of our knowledge
makes clear, he thinks, that we are in the possession of a great deal
of information that is not of the unsatisfactory kind that, according
to Hume, all our knowledge of things must be. There, for example, are
all the truths of mathematics. When we enunciate a truth regarding the
relations of the lines and angles of a triangle, we are not merely
unfolding in the predicate of our proposition what was implicitly
contained in the subject. There are propositions that do no more than
this; they are _analytical_, _i.e._ they merely analyze the subject.
Thus, when we say: Man is a rational animal, we may merely be defining
the word "man"--unpacking it, so to speak. But a _synthetic_ judgment
is one in which the predicate is not contained in the subject; it adds
to one's information. The mathematical truths are of this character.
So also is the truth that everything that happens must have a cause.
Do we connect things with one another in this way merely because we
have had _experience_ that they are thus connected? Is it because they
are _given_ to us connected in this way? That cannot be the case, Kant
argues, for what is taken up as mere experienced act cannot be known as
universally and necessarily true. We perceive that these things _must_
be so connected. How shall we explain this necessity?
We can only explain it, said Kant, in this way: We must assume that
what is given us from without is merely the raw material of sensation,
the _matter_ of our experience; and that the ordering of this matter,
the arranging it into a world of phenomena, the furnishing of _form_,
is the work of the mind. Thus, we must think of space, time,
causality, and of all other relations which obtain between the elements
of our experience, as due to the nature of the mind. It perceives the
world of phenomena that it does, because it _constructs_ that world.
Its knowledge of things is stable and dependable because it cannot know
any phenomenon which does not conform to its laws. The water poured
into a cup must take the shape of the cup; and the raw materials poured
into a mind must take the form of an orderly world, spread out in space
and time.
Kant thought that with this turn he had placed human knowledge upon a
satisfactory basis, and had, at the same time, indicated the
limitations of human knowledge. If the world we perceive is a world
which we make; if the forms of thought furnished by the mind have no
other function than the ordering of the materials furnished by sense;
then what can we say of that which may be beyond phenomena? What of
_noumena_?
It seems clear that, on Kant's principles, we ought not to be able to
say anything whatever of _noumena_. To say that such may exist appears
absurd. All conceivable connection between them and existing things as
we know them is cut off. We cannot think of a noumenon as a
_substance_, for the notions of substance and quality have been
declared to be only a scheme for the ordering of phenomena. Nor can we
think of one as a cause of the sensations that we unite into a world,
for just the same reason. We are shut up logically to the world of
phenomena, and that world of phenomena is, after all, the successor of
the world of ideas advocated by Berkeley.
This is not the place to discuss at length the value of Kant's
contribution to philosophy.[3] There is something terrifying in the
prodigious length at which it seems possible for men to discuss it.
Kant called his doctrine "Criticism," because it undertook to establish
the nature and limits of our knowledge. By some he has been hailed as
a great enlightener, and by others he has been accused of being as
dogmatic in his assumptions as those whom he disapproved.
But one thing he certainly has accomplished. He has made the words
"phenomena" and "noumena" familiar to us all, and he has induced a vast
number of men to accept it as established fact that it is not worth
while to try to extend our knowledge beyond phenomena. One sees his
influence in the writings of men who differ most widely from one
another.
[1] "Essay," Book IV, Chapter XI, section 7.
[2] "An Inquiry into the Human Mind," Chapter V, section 5.
[3] The reader will find a criticism of the Critical Philosophy in