II
THE PLACE OF SCIENCE IN A LIBERAL EDUCATION
I
Science, to the ordinary reader of newspapers, is represented by a
varying selection of sensational triumphs, such as wireless telegraphy
and aeroplanes, radio-activity and the marvels of modern alchemy. It is
not of this aspect of science that I wish to speak. Science, in this
aspect, consists of detached up-to-date fragments, interesting only
until they are replaced by something newer and more up-to-date,
displaying nothing of the systems of patiently constructed knowledge
out of which, almost as a casual incident, have come the practically
useful results which interest the man in the street. The increased
command over the forces of nature which is derived from science is
undoubtedly an amply sufficient reason for encouraging scientific
research, but this reason has been so often urged and is so easily
appreciated that other reasons, to my mind quite as important, are apt
to be overlooked. It is with these other reasons, especially with the
intrinsic value of a scientific habit of mind in forming our outlook
on the world, that I shall be concerned in what follows.
The instance of wireless telegraphy will serve to illustrate the
difference between the two points of view. Almost all the serious
intellectual labour required for the [34]possibility of this invention is
due to three men, Faraday, Maxwell, and Hertz. In alternating layers
of experiment and theory these three men built up the modern theory of
electromagnetism, and demonstrated the identity of light with
electromagnetic waves. The system which they discovered is one of
profound intellectual interest, bringing together and unifying an
endless variety of apparently detached phenomena, and displaying a
cumulative mental power which cannot but afford delight to every
generous spirit. The mechanical details which remained to be adjusted
in order to utilise their discoveries for a practical system of
telegraphy demanded, no doubt, very considerable ingenuity, but had
not that broad sweep and that universality which could give them
intrinsic interest as an object of disinterested contemplation.
From the point of view of training the mind, of giving that
well-informed, impersonal outlook which constitutes culture in the
good sense of this much-misused word, it seems to be generally held
indisputable that a literary education is superior to one based on
science. Even the warmest advocates of science are apt to rest their
claims on the contention that culture ought to be sacrificed to
utility. Those men of science who respect culture, when they associate
with men learned in the classics, are apt to admit, not merely
politely, but sincerely, a certain inferiority on their side,
compensated doubtless by the services which science renders to
humanity, but none the less real. And so long as this attitude exists
among men of science, it tends to verify itself: the intrinsically
valuable aspects of science tend to be sacrificed to the merely
useful, and little attempt is made to preserve that leisurely,
systematic survey by which the finer quality of mind is formed and
nourished.
But even if there be, in present fact, any such inferiority as is supposed in the educational value of science, this is, I believe, not the fault of science itself, but the fault of the spirit in which science is taught. If its full possibilities were realised by those who teach it, I believe that its capacity of producing those habits of mind which constitute the highest mental excellence would be at least as great as that of literature, and more particularly of Greek and Latin literature. In saying this I have no wish whatever to disparage a classical education. I have not myself enjoyed its benefits, and my knowledge of Greek and Latin authors is derived almost wholly from translations. But I am firmly persuaded that the Greeks fully deserve all the admiration that is bestowed upon them, and that it is a very great and serious loss to be unacquainted with their writings. It is not by attacking them, but by drawing attention to neglected excellences in science, that I wish to conduct my argument.
One defect, however, does seem inherent in a purely classical
education—namely, a too exclusive emphasis on the past. By the study
of what is absolutely ended and can never be renewed, a habit of
criticism towards the present and the future is engendered. The
qualities in which the present excels are qualities to which the study
of the past does not direct attention, and to which, therefore, the
student of Greek civilisation may easily become blind. In what is new
and growing there is apt to be something crude, insolent, even a
little vulgar, which is shocking to the man of sensitive taste;
quivering from the rough contact, he retires to the trim gardens of a
polished past, forgetting that they were reclaimed from the wilderness
by men as rough and earth-soiled as those from whom he shrinks in his
own day. The habit of being unable to recognise merit until it is
dead is too apt to be the result of a purely bookish life, and a
culture based wholly on the past will seldom be able to pierce through
everyday surroundings to the essential splendour of contemporary
things, or to the hope of still greater splendour in the future.
"My eyes saw not the men of old;
And now their age away has rolled.
I weep to think I shall not see
The heroes of posterity."
So says the Chinese poet; but such impartiality is rare in the more
pugnacious atmosphere of the West, where the champions of past and
future fight a never-ending battle, instead of combining to seek out
the merits of both.
This consideration, which militates not only against the exclusive
study of the classics, but against every form of culture which has
become static, traditional, and academic, leads inevitably to the
fundamental question:
What is the true end of education ? But before attempting to answer this question it will be well to define the sense in which we are to use the word "education." For this purpose I shall distinguish the sense in which I mean to use it from two others, both perfectly legitimate, the one broader and the other narrower than the sense in which I mean to use the word.
What is the true end of education ? But before attempting to answer this question it will be well to define the sense in which we are to use the word "education." For this purpose I shall distinguish the sense in which I mean to use it from two others, both perfectly legitimate, the one broader and the other narrower than the sense in which I mean to use the word.
In the broader sense, education will include not only what we learn
through instruction, but all that we learn through personal
experience the formation of character through the education of life.
Of this aspect of education, vitally important as it is, I will say
nothing, since its consideration would introduce topics quite foreign
to the question with which we are concerned.
In the narrower sense, education may be confined to instruction, the
imparting of definite information on various subjects, because such
information, in and for itself, is useful in daily life. Elementary
education, reading, writing, and arithmetic is almost wholly of this
kind. But instruction, necessary as it is, does not per se
constitute education in the sense in which I wish to consider it.
Education, in the sense in which I mean it, may be defined as the
formation, by means of instruction, of certain mental habits and a
certain outlook on life and the world. It remains to ask ourselves,
what mental habits, and what sort of outlook, can be hoped for as the
result of instruction? When we have answered this question we can
attempt to decide what science has to contribute to the formation of
the habits and outlook which we desire.
Our whole life is built about a certain number, not a very small
number, of primary instincts and impulses.
Only what is in some way connected with these instincts and impulses appears to us desirable or important; there is no faculty, whether "reason" or "virtue" or whatever it may be called, that can take our active life and our hopes and fears outside the region controlled by these first movers of all desire. Each of them is like a queen-bee, aided by a hive of workers gathering honey; but when the queen is gone the workers languish and die, and the cells remain empty of their expected sweetness. So with each primary impulse in civilised man: it is surrounded and protected by a busy swarm of attendant derivative desires, which store up in its service whatever honey the surrounding world affords. But if the queen-impulse dies, the death-dealing influence, though retarded a little by habit, spreads slowly through all the subsidiary impulses, and a whole tract of life becomes inexplicably colourless. What was formerly full of zest, and so obviously worth doing that it raised no questions, has now grown dreary and purposeless: with a sense of disillusion we inquire the meaning of life, and decide, perhaps, that all is vanity. The search for an outside meaning that can compel an inner response must always be disappointed: all "meaning" must be at bottom related to our primary desires, and when they are extinct no miracle can restore to the world the value which they reflected upon it.
Only what is in some way connected with these instincts and impulses appears to us desirable or important; there is no faculty, whether "reason" or "virtue" or whatever it may be called, that can take our active life and our hopes and fears outside the region controlled by these first movers of all desire. Each of them is like a queen-bee, aided by a hive of workers gathering honey; but when the queen is gone the workers languish and die, and the cells remain empty of their expected sweetness. So with each primary impulse in civilised man: it is surrounded and protected by a busy swarm of attendant derivative desires, which store up in its service whatever honey the surrounding world affords. But if the queen-impulse dies, the death-dealing influence, though retarded a little by habit, spreads slowly through all the subsidiary impulses, and a whole tract of life becomes inexplicably colourless. What was formerly full of zest, and so obviously worth doing that it raised no questions, has now grown dreary and purposeless: with a sense of disillusion we inquire the meaning of life, and decide, perhaps, that all is vanity. The search for an outside meaning that can compel an inner response must always be disappointed: all "meaning" must be at bottom related to our primary desires, and when they are extinct no miracle can restore to the world the value which they reflected upon it.
The purpose of education, therefore, cannot be to create any primary
impulse which is lacking in the uneducated; the purpose can only be to
enlarge the scope of those that human nature provides, by increasing
the number and variety of attendant thoughts, and by showing where the
most permanent satisfaction is to be found. Under the impulse of a
Calvinistic horror of the "natural man," this obvious truth has been
too often misconceived in the training of the young; "nature" has been
falsely regarded as excluding all that is best in what is natural, and
the endeavour to teach virtue has led to the production of stunted and
contorted hypocrites instead of full-grown human beings. From such
mistakes in education a better psychology or a kinder heart is
beginning to preserve the present generation; we need, therefore,
waste no more words on the theory that the purpose of education is to
thwart or eradicate nature.
But although nature must supply the initial force of desire, nature is
not, in the civilised man, the spasmodic, fragmentary, and yet violent
set of impulses that it is in the savage. Each impulse has its
constitutional ministry of thought and knowledge and reflection,
through which possible conflicts of impulses are foreseen, and
temporary impulses are controlled by the unifying impulse which may be
called wisdom. In this way education destroys the crudity of
instinct, and increases through knowledge the wealth and variety of
the individual's contacts with the outside world, making him no longer
an isolated fighting unit, but a citizen of the universe, embracing
distant countries, remote regions of space, and vast stretches of past
and future within the circle of his interests. It is this simultaneous
softening in the insistence of desire and enlargement of its scope
that is the chief moral end of education.
Closely connected with this moral end is the more purely intellectual
aim of education, the endeavour to make us see and imagine the world
in an objective manner, as far as possible as it is in itself, and not
merely through the distorting medium of personal desire. The complete
attainment of such an objective view is no doubt an ideal,
indefinitely approachable, but not actually and fully realisable.
Education, considered as a process of forming our mental habits and
our outlook on the world, is to be judged successful in proportion as
its outcome approximates to this ideal; in proportion, that is to say,
as it gives us a true view of our place in society, of the relation of
the whole human society to its non-human environment, and of the
nature of the non-human world as it is in itself apart from our
desires and interests. If this standard is admitted, we can return to
the consideration of science, inquiring how far science contributes to
such an aim, and whether it is in any respect superior to its rivals
in educational practice.
II
Two opposite and at first sight conflicting merits belong to science
as against literature and art. The one, which is not inherently
necessary, but is certainly true [40]at the present day, is hopefulness
as to the future of human achievement, and in particular as to the
useful work that may be accomplished by any intelligent student. This
merit and the cheerful outlook which it engenders prevent what might
otherwise be the depressing effect of another aspect of science, to my
mind also a merit, and perhaps its greatest merit, I mean the
irrelevance of human passions and of the whole subjective apparatus
where scientific truth is concerned. Each of these reasons for
preferring the study of science requires some amplification. Let us
begin with the first.
In the study of literature or art our attention is perpetually riveted
upon the past: the men of Greece or of the Renaissance did better than
any men do now; the triumphs of former ages, so far from facilitating
fresh triumphs in our own age, actually increase the difficulty of
fresh triumphs by rendering originality harder of attainment; not only
is artistic achievement not cumulative, but it seems even to depend
upon a certain freshness and naïveté of impulse and vision which
civilisation tends to destroy. Hence comes, to those who have been
nourished on the literary and artistic productions of former ages, a
certain peevishness and undue fastidiousness towards the present, from
which there seems no escape except into the deliberate vandalism which
ignores tradition and in the search after originality achieves only
the eccentric. But in such vandalism there is none of the simplicity
and spontaneity out of which great art springs: theory is still the
canker in its core, and insincerity destroys the advantages of a
merely pretended ignorance.
The despair thus arising from an education which suggests no
pre-eminent mental activity except that of artistic creation is wholly
absent from an education which gives the knowledge of scientific
method. The discovery of scientific method, except in pure
mathematics, is a thing of yesterday; speaking broadly, we may say
that it dates from Galileo. Yet already it has transformed the world,
and its success proceeds with ever-accelerating velocity. In science
men have discovered an activity of the very highest value in which
they are no longer, as in art, dependent for progress upon the
appearance of continually greater genius, for in science the
successors stand upon the shoulders of their predecessors; where one
man of supreme genius has invented a method, a thousand lesser men can
apply it. No transcendent ability is required in order to make useful
discoveries in science; the edifice of science needs its masons,
bricklayers, and common labourers as well as its foremen,
master-builders, and architects. In art nothing worth doing can be
done without genius; in science even a very moderate capacity can
contribute to a supreme achievement.
In science the man of real genius is the man who invents a new method.
The notable discoveries are often made by his successors, who can
apply the method with fresh vigour, unimpaired by the previous labour
of perfecting it; but the mental calibre of the thought required for
their work, however brilliant, is not so great as that required by the
first inventor of the method. There are in science immense numbers of
different methods, appropriate to different classes of problems; but
over and above them all, there is something not easily definable,
which may be called the method of science. It was formerly customary
to identify this with the inductive method, and to associate it with
the name of Bacon. But the true inductive method was not discovered by
Bacon, and the true method of science is something which includes
deduction as much as induction, logic and mathematics as much as
botany and geology. I shall not attempt the difficult task of stating
what the scientific method is, but I will try to indicate the temper
of mind out of which the scientific method grows, which is the second
of the two merits that were mentioned above as belonging to a
scientific education.
The kernel of the scientific outlook is a thing so simple, so obvious,
so seemingly trivial, that the mention of it may almost excite
derision. The kernel of the scientific outlook is the refusal to
regard our own desires, tastes, and interests as affording a key to
the understanding of the world. Stated thus baldly, this may seem no
more than a trite truism. But to remember it consistently in matters
arousing our passionate partisanship is by no means easy, especially
where the available evidence is uncertain and inconclusive. A few
illustrations will make this clear.
Aristotle, I understand, considered that the stars must move in
circles because the circle is the most perfect curve. In the absence
of evidence to the contrary, he allowed himself to decide a question
of fact by an appeal to æsthetico-moral considerations. In such a case
it is at once obvious to us that this appeal was unjustifiable.
We know now how to ascertain as a fact the way in which the heavenly bodies move, and we know that they do not move in circles, or even in accurate ellipses, or in any other kind of simply describable curve. This may be painful to a certain hankering after simplicity of pattern in the universe, but we know that in astronomy such feelings are irrelevant. Easy as this knowledge seems now, we owe it to the courage and insight of the first inventors of scientific method, and more especially of Galileo.
We know now how to ascertain as a fact the way in which the heavenly bodies move, and we know that they do not move in circles, or even in accurate ellipses, or in any other kind of simply describable curve. This may be painful to a certain hankering after simplicity of pattern in the universe, but we know that in astronomy such feelings are irrelevant. Easy as this knowledge seems now, we owe it to the courage and insight of the first inventors of scientific method, and more especially of Galileo.
We may take as another illustration Malthus's doctrine of population.
This illustration is all the better for the fact that his actual
doctrine is now known to be largely erroneous. It is not his
conclusions that are valuable, but the temper and method of his
inquiry. As everyone knows, it was to him that Darwin owed an
essential part of his theory of natural selection, and this was only
possible because Malthus's outlook was truly scientific. His great
merit lies in considering man not as the object of praise or blame,
but as a part of nature, a thing with a certain characteristic
behaviour from which certain consequences must follow. If the
behaviour is not quite what Malthus supposed, if the consequences are
not quite what he inferred, that may falsify his conclusions, but does
not impair the value of his method. The objections which were made
when his doctrine was new that it was horrible and depressing, that
people ought not to act as he said they did, and so on were all such
as implied an unscientific attitude of mind; as against all of them,
his calm determination to treat man as a natural phenomenon marks an
important advance over the reformers of the eighteenth century and the
Revolution.
Under the influence of Darwinism the scientific attitude towards man
has now become fairly common, and is to some people quite natural,
though to most it is still a difficult and artificial intellectual
contortion. There is however, one study which is as yet almost wholly
untouched by the scientific spirit, I mean the study of philosophy.
Philosophers and the public imagine that the scientific spirit must
pervade pages that bristle with allusions to ions, germ-plasms, and
the eyes of shell-fish. But as the devil can quote Scripture, so the
philosopher can quote science. The scientific spirit is not an affair
of quotation, of externally acquired information, any more than
manners are an affair of the etiquette-book. The scientific attitude
of mind involves a sweeping away of all other desires in the interests
of the desire to know, it involves suppression of hopes and fears,
loves and hates, and the whole subjective emotional life, until we
become subdued to the material, able to see it frankly, without
preconceptions, without bias, without any wish except to see it as it
is, and without any belief that what it is must be determined by some
relation, positive or negative, to what we should like it to be, or to
what we can easily imagine it to be.
Now in philosophy this attitude of mind has not as yet been achieved.
A certain self-absorption, not personal, but human, has marked almost
all attempts to conceive the universe as a whole. Mind, or some aspect
of it, thought or will or sentience, has been regarded as the pattern
after which the universe is to be conceived, for no better reason, at
bottom, than that such a universe would not seem strange, and would
give us the cosy feeling that every place is like home. To conceive
the universe as essentially progressive or essentially deteriorating,
for example, is to give to our hopes and fears a cosmic importance
which may, of course, be justified, but which we have as yet no
reason to suppose justified. Until we have learnt to think of it in
ethically neutral terms, we have not arrived at a scientific attitude
in philosophy; and until we have arrived at such an attitude, it is
hardly to be hoped that philosophy will achieve any solid results.
I have spoken so far largely of the negative aspect of the scientific
spirit, but it is from the positive aspect that its value is derived.
The instinct of constructiveness, which is one of the chief incentives
to artistic creation, can find in scientific systems a satisfaction
more massive than any epic poem. Disinterested curiosity, which is the
source of almost all intellectual effort, finds with astonished
delight that science can unveil secrets which might well have seemed
for ever undiscoverable. The desire for a larger life and wider
interests, for an escape from private circumstances, and even from the
whole recurring human cycle of birth and death, is fulfilled by the
impersonal cosmic outlook of science as by nothing else. To all these
must be added, as contributing to the happiness of the man of science,
the admiration of splendid achievement, and the consciousness of
inestimable utility to the human race. A life devoted to science is
therefore a happy life, and its happiness is derived from the very
best sources that are open to dwellers on this troubled and passionate
planet.
A FREE MAN'S WORSHIP
To Dr. Faustus in his study Mephistopheles told the history of the
Creation, saying:
"The endless praises of the choirs of angels had begun to grow
wearisome; for, after all, did he not deserve their praise ? Had he not
given them endless joy ? Would it not be more amusing to obtain
undeserved praise, to be worshipped by beings whom he tortured ? He
smiled inwardly, and resolved that the great drama should be
performed.
"For countless ages the hot nebula whirled aimlessly through space. At
length it began to take shape, the central mass threw off planets, the
planets cooled, boiling seas and burning mountains heaved and tossed,
from black masses of cloud hot sheets of rain deluged the barely solid
crust. And now the first germ of life grew in the depths of the ocean,
and developed rapidly in the fructifying warmth into vast forest
trees, huge ferns springing from the damp mould, sea monsters
breeding, fighting, devouring, and passing away. And from the
monsters, as the play unfolded itself, Man was born, with the power of
thought, the knowledge of good and evil, and the cruel thirst for
worship. And Man saw that all is passing in this mad, monstrous world,
that all is struggling to snatch, at any cost, a few brief moments of
life before Death's inexorable decree.
And Man said: 'There is a hidden purpose, could we but fathom it, and the purpose is good; for we must reverence something, and in the visible world there is nothing worthy of reverence.' And Man stood aside from the struggle, resolving that God intended harmony to come out of chaos by human efforts. And when he followed the instincts which God had transmitted to him from his ancestry of beasts of prey, he called it Sin, and asked God to forgive him. But he doubted whether he could be justly forgiven, until he invented a divine Plan by which God's wrath was to have been appeased. And seeing the present was bad, he made it yet worse, that thereby the future might be better. And he gave God thanks for the strength that enabled him to forgo even the joys that were possible. And God smiled; and when he saw that Man had become perfect in renunciation and worship, he sent another sun through the sky, which crashed into Man's sun; and all returned again to nebula.
And Man said: 'There is a hidden purpose, could we but fathom it, and the purpose is good; for we must reverence something, and in the visible world there is nothing worthy of reverence.' And Man stood aside from the struggle, resolving that God intended harmony to come out of chaos by human efforts. And when he followed the instincts which God had transmitted to him from his ancestry of beasts of prey, he called it Sin, and asked God to forgive him. But he doubted whether he could be justly forgiven, until he invented a divine Plan by which God's wrath was to have been appeased. And seeing the present was bad, he made it yet worse, that thereby the future might be better. And he gave God thanks for the strength that enabled him to forgo even the joys that were possible. And God smiled; and when he saw that Man had become perfect in renunciation and worship, he sent another sun through the sky, which crashed into Man's sun; and all returned again to nebula.
"'Yes,' he murmured, 'it was a good play; I will have it performed
again.'"
Such, in outline, but even more purposeless, more void of meaning, is
the world which Science presents for our belief. Amid such a world, if
anywhere, our ideals henceforward must find a home. That Man is the
product of causes which had no prevision of the end they were
achieving; that his origin, his growth, his hopes and fears, his loves
and his beliefs, are but the outcome of accidental collocations of
atoms; that no fire, no heroism, no intensity of thought and feeling,
can preserve an individual life beyond the grave; that all the labours
of the ages, all the devotion, all the inspiration, all the noonday
brightness of human genius, are destined to extinction in the vast
death of the solar system, and that the whole temple of Man's
achievement must inevitably be buried beneath the débris of a universe
in ruins, all these things, if not quite beyond dispute, are yet so
nearly certain, that no philosophy which rejects them can hope to
stand. Only within the scaffolding of these truths, only on the firm
foundation of unyielding despair, can the soul's habitation henceforth
be safely built.
How, in such an alien and inhuman world, can so powerless a creature
as Man preserve his aspirations untarnished ? A strange mystery it is
that Nature, omnipotent but blind, in the revolutions of her secular
hurryings through the abysses of space, has brought forth at last a
child, subject still to her power, but gifted with sight, with
knowledge of good and evil, with the capacity of judging all the works
of his unthinking Mother. In spite of Death, the mark and seal of the
parental control, Man is yet free, during his brief years, to examine,
to criticise, to know, and in imagination to create. To him alone, in
the world with which he is acquainted, this freedom belongs; and in
this lies his superiority to the resistless forces that control his
outward life.
The savage, like ourselves, feels the oppression of his impotence
before the powers of Nature; but having in himself nothing that he
respects more than Power, he is willing to prostrate himself before
his gods, without inquiring whether they are worthy of his worship.
Pathetic and very terrible is the long history of cruelty and torture,
of degradation and human sacrifice, endured in the hope of placating
the jealous gods: surely, the trembling believer thinks, when what is
most precious has been freely given, their lust for blood must be
appeased, and more will not be required. The religion of Moloch, as
such creeds may be generically called, is in essence the cringing
submission of the slave, who dare not, even in his heart, allow the
thought that his master deserves no adulation. Since the independence
of ideals is not yet acknowledged, Power may be freely worshipped, and
receive an unlimited respect, despite its wanton infliction of pain.
But gradually, as morality grows bolder, the claim of the ideal world
begins to be felt; and worship, if it is not to cease, must be given
to gods of another kind than those created by the savage. Some, though
they feel the demands of the ideal, will still consciously reject
them, still urging that naked Power is worthy of worship. Such is the
attitude inculcated in God's answer to Job out of the whirlwind: the
divine power and knowledge are paraded, but of the divine goodness
there is no hint. Such also is the attitude of those who, in our own
day, base their morality upon the struggle for survival, maintaining
that the survivors are necessarily the fittest. But others, not
content with an answer so repugnant to the moral sense, will adopt the
position which we have become accustomed to regard as specially
religious, maintaining that, in some hidden manner, the world of fact
is really harmonious with the world of ideals. Thus Man creates God,
all-powerful and all-good, the mystic unity of what is and what should
be.
But the world of fact, after all, is not good; and, in submitting our
judgment to it, there is an element of slavishness from which our
thoughts must be purged. For in all things it is well to exalt the
dignity of Man, by freeing him as far as possible from the tyranny of
non-human Power. When we have realised that Power is largely bad, that
man, with his knowledge of good and evil, is but a helpless atom in a
world which has no such knowledge, the choice is again presented to
us: Shall we worship Force, or shall we worship Goodness ? Shall our
God exist and be evil, or shall he be recognised as the creation of
our own conscience ?
The answer to this question is very momentous, and affects profoundly
our whole morality. The worship of Force, to which Carlyle and
Nietzsche and the creed of Militarism have accustomed us, is the
result of failure to maintain our own ideals against a hostile
universe: it is itself a prostrate submission to evil, a sacrifice of
our best to Moloch. If strength indeed is to be respected, let us
respect rather the strength of those who refuse that false
"recognition of facts" which fails to recognise that facts are often
bad. Let us admit that, in the world we know, there are many things
that would be better otherwise, and that the ideals to which we do and
must adhere are not realised in the realm of matter. Let us preserve
our respect for truth, for beauty, for the ideal of perfection which
life does not permit us to attain, though none of these things meet
with the approval of the unconscious universe. If Power is bad, as it
seems to be, let us reject it from our hearts. In this lies Man's true
freedom: in determination to worship only the God created by our own
love of the good, to respect only the heaven which inspires the
insight of our best moments. In action, in desire, we must submit
perpetually to the tyranny of outside forces; but in thought, in
aspiration, we are free, free from our fellow-men, free from the petty
planet on which our bodies impotently crawl, free even, while we live,
from the tyranny of death. Let us learn, then, that energy of faith
which enables us to live constantly in the vision of the good; and let
us descend, in action, into the world of fact, with that vision always
before us.
When first the opposition of fact and ideal grows fully visible, a
spirit of fiery revolt, of fierce hatred of the gods, seems necessary
to the assertion of freedom. To defy with Promethean constancy a
hostile universe, to keep its evil always in view, always actively
hated, to refuse no pain that the malice of Power can invent, appears
to be the duty of all who will not bow before the inevitable. But
indignation is still a bondage, for it compels our thoughts to be
occupied with an evil world; and in the fierceness of desire from
which rebellion springs there is a kind of self-assertion which it is
necessary for the wise to overcome. Indignation is a submission of our
thoughts, but not of our desires; the Stoic freedom in which wisdom
consists is found in the submission of our desires, but not of our
thoughts. From the submission of our desires springs the virtue of
resignation; from the freedom of our thoughts springs the whole world
of art and philosophy, and the vision of beauty by which, at last, we
half reconquer the reluctant world. But the vision of beauty is
possible only to unfettered contemplation, to thoughts not weighted by
the load of eager wishes; and thus Freedom comes only to those who no
longer ask of life that it shall yield them any of those personal
goods that are subject to the mutations of Time.
Although the necessity of renunciation is evidence of the existence of
evil, yet Christianity, in preaching it, has shown a wisdom exceeding
that of the Promethean philosophy of rebellion. It must be admitted
that, of the things we desire, some, though they prove impossible, are
yet real goods; others, however, as ardently longed for, do not form
part of a fully purified ideal. The belief that what must be renounced
is bad, though sometimes false, is far less often false than untamed
passion supposes; and the creed of religion, by providing a reason for proving that it is never false, has been the means of purifying
our hopes by the discovery of many austere truths.
But there is in resignation a further good element: even real goods,
when they are unattainable, ought not to be fretfully desired. To
every man comes, sooner or later, the great renunciation. For the
young, there is nothing unattainable; a good thing desired with the
whole force of a passionate will, and yet impossible, is to them not
credible. Yet, by death, by illness, by poverty, or by the voice of
duty, we must learn, each one of us, that the world was not made for
us, and that, however beautiful may be the things we crave, Fate may
nevertheless forbid them. It is the part of courage, when misfortune
comes, to bear without repining the ruin of our hopes, to turn away
our thoughts from vain regrets. This degree of submission to Power is
not only just and right: it is the very gate of wisdom.
But passive renunciation is not the whole of wisdom; for not by
renunciation alone can we build a temple for the worship of our own
ideals. Haunting foreshadowings of the temple appear in the realm of
imagination, in music, in architecture, in the untroubled kingdom of
reason, and in the golden sunset magic of lyrics, where beauty shines
and glows, remote from the touch of sorrow, remote from the fear of
change, remote from the failures and disenchantments of the world of
fact. In the contemplation of these things the vision of heaven will
shape itself in our hearts, giving at once a touchstone to judge the
world about us, and an inspiration by which to fashion to our needs
whatever is not incapable of serving as a stone in the sacred temple.
Except for those rare spirits that are born without sin, there is a
cavern of darkness to be traversed before that temple can be entered.
The gate of the cavern is despair, and its floor is paved with the
gravestones of abandoned hopes. There Self must die; there the
eagerness, the greed of untamed desire must be slain, for only so can
the soul be freed from the empire of Fate. But out of the cavern the
Gate of Renunciation leads again to the daylight of wisdom, by whose
radiance a new insight, a new joy, a new tenderness, shine forth to
gladden the pilgrim's heart.
When, without the bitterness of impotent rebellion, we have learnt
both to resign ourselves to the outward rule of Fate and to recognise
that the non-human world is unworthy of our worship, it becomes
possible at last so to transform and refashion the unconscious
universe, so to transmute it in the crucible of imagination, that a
new image of shining gold replaces the old idol of clay. In all the
multiform facts of the world in the visual shapes of trees and
mountains and clouds, in the events of the life of man, even in the
very omnipotence of Death, the insight of creative idealism can find
the reflection of a beauty which its own thoughts first made. In this
way mind asserts its subtle mastery over the thoughtless forces of
Nature. The more evil the material with which it deals, the more
thwarting to untrained desire, the greater is its achievement in
inducing the reluctant rock to yield up its hidden treasures, the
prouder its victory in compelling the opposing forces to swell the
pageant of its triumph. Of all the arts, Tragedy is the proudest, the
most triumphant; for it builds its shining citadel in the very centre
of the enemy's country, on the very summit of his highest mountain;
from its impregnable watchtowers, his camps and arsenals, his columns
and forts, are all revealed; within its walls the free life continues,
while the legions of Death and Pain and Despair, and all the servile
captains of tyrant Fate, afford the burghers of that dauntless city
new spectacles of beauty. Happy those sacred ramparts, thrice happy
the dwellers on that all-seeing eminence. Honour to those brave
warriors who, through countless ages of warfare, have preserved for us
the priceless heritage of liberty, and have kept undefiled by
sacrilegious invaders the home of the unsubdued.
But the beauty of Tragedy does but make visible a quality which, in
more or less obvious shapes, is present always and everywhere in life.
In the spectacle of Death, in the endurance of intolerable pain, and
in the irrevocableness of a vanished past, there is a sacredness, an
overpowering awe, a feeling of the vastness, the depth, the
inexhaustible mystery of existence, in which, as by some strange
marriage of pain, the sufferer is bound to the world by bonds of
sorrow. In these moments of insight, we lose all eagerness of
temporary desire, all struggling and striving for petty ends, all care
for the little trivial things that, to a superficial view, make up the
common life of day by day; we see, surrounding the narrow raft
illumined by the flickering light of human comradeship, the dark ocean
on whose rolling waves we toss for a brief hour; from the great night
without, a chill blast breaks in upon our refuge; all the loneliness
of humanity amid hostile forces is concentrated upon the individual
soul, which must struggle alone, with what of courage it can command,
against the whole weight of a universe that cares nothing for its
hopes and fears. Victory, in this struggle with the powers of
darkness, is the true baptism into the glorious company of heroes, the
true initiation into the overmastering beauty of human existence. From
that awful encounter of the soul with the outer world, renunciation,
wisdom, and charity are born; and with their birth a new life begins.
To take into the inmost shrine of the soul the irresistible forces
whose puppets we seem to be Death and change, the irrevocableness of
the past, and the powerlessness of man before the blind hurry of the
universe from vanity to vanity—to feel these things and know them is
to conquer them.
This is the reason why the Past has such magical power. The beauty of
its motionless and silent pictures is like the enchanted purity of
late autumn, when the leaves, though one breath would make them fall,
still glow against the sky in golden glory. The Past does not change
or strive; like Duncan, after life's fitful fever it sleeps well; what
was eager and grasping, what was petty and transitory, has faded away,
the things that were beautiful and eternal shine out of it like stars
in the night. Its beauty, to a soul not worthy of it, is unendurable;
but to a soul which has conquered Fate it is the key of religion.
The life of Man, viewed outwardly, is but a small thing in comparison
with the forces of Nature. The slave is doomed to worship Time and
Fate and Death, because they are greater than anything he finds in
himself, and because all his thoughts are of things which they devour.
But, great as they are, to think of them greatly, to feel their
passionless splendour, is greater still. And such thought makes us
free men; we no longer bow before the inevitable in Oriental
subjection, but we absorb it, and make it a part of ourselves. To
abandon the struggle for private happiness, to expel all eagerness of
temporary desire, to burn with passion for eternal things this is
emancipation, and this is the free man's worship. And this liberation
is effected by a contemplation of Fate; for Fate itself is subdued by
the mind which leaves nothing to be purged by the purifying fire of
Time.
United with his fellow-men by the strongest of all ties, the tie of a
common doom, the free man finds that a new vision is with him always,
shedding over every daily task the light of love. The life of Man is a
long march through the night, surrounded by invisible foes, tortured
by weariness and pain, towards a goal that few can hope to reach, and
where none may tarry long. One by one, as they march, our comrades
vanish from our sight, seized by the silent orders of omnipotent
Death. Very brief is the time in which we can help them, in which
their happiness or misery is decided. Be it ours to shed sunshine on
their path, to lighten their sorrows by the balm of sympathy, to give
them the pure joy of a never-tiring affection, to strengthen failing
courage, to instil faith in hours of despair. Let us not weigh in
grudging scales their merits and demerits, but let us think only of
their need of the sorrows, the difficulties, perhaps the blindnesses,
that make the misery of their lives; let us remember that they are
fellow-sufferers in the same darkness, actors in the same tragedy with
ourselves. And so, when their day is over, when their good and their
evil have become eternal by the immortality of the past, be it ours to
feel that, where they suffered, where they failed, no deed of ours was
the cause; but wherever a spark of the divine fire kindled in their
hearts, we were ready with encouragement, with sympathy, with brave
words in which high courage glowed.
Brief and powerless is Man's life; on him and all his race the slow,
sure doom falls pitiless and dark. Blind to good and evil, reckless of
destruction, omnipotent matter rolls on its relentless way; for Man,
condemned to-day to lose his dearest, to-morrow himself to pass through the gate of darkness, it remains only to cherish, ere yet the
blow falls, the lofty thoughts that ennoble his little day; disdaining
the coward terrors of the slave of Fate, to worship at the shrine that
his own hands have built; undismayed by the empire of chance, to
preserve a mind free from the wanton tyranny that rules his outward
life; proudly defiant of the irresistible forces that tolerate, for a
moment, his knowledge and his condemnation, to sustain alone, a weary
but unyielding Atlas, the world that his own ideals have fashioned
despite the trampling march of unconscious power.
IV
THE STUDY OF MATHEMATICS
In regard to every form of human activity it is necessary that the
question should be asked from time to time, What is its purpose and
ideal? In what way does it contribute to the beauty of human
existence ? As respects those pursuits which contribute only remotely,
by providing the mechanism of life, it is well to be reminded that not
the mere fact of living is to be desired, but the art of living in the
contemplation of great things. Still more in regard to those
avocations which have no end outside themselves, which are to be
justified, if at all, as actually adding to the sum of the world's
permanent possessions, it is necessary to keep alive a knowledge of
their aims, a clear prefiguring vision of the temple in which creative
imagination is to be embodied.
The fulfilment of this need, in what concerns the studies forming the
material upon which custom has decided to train the youthful mind, is
indeed sadly remote, so remote as to make the mere statement of such a
claim appear preposterous. Great men, fully alive to the beauty of the
contemplations to whose service their lives are devoted, desiring that
others may share in their joys, persuade mankind to impart to the
successive generations the mechanical knowledge without which it is
impossible to cross the threshold. Dry pedants possess themselves of
the privilege of instilling this knowledge: they forget that it is to
serve but as a key to open the doors of the temple; though they spend
their lives on the steps leading up to those sacred doors, they turn
their backs upon the temple so resolutely that its very existence is
forgotten, and the eager youth, who would press forward to be
initiated to its domes and arches, is bidden to turn back and count
the steps.
Mathematics, perhaps more even than the study of Greece and Rome, has
suffered from this oblivion of its due place in civilisation. Although
tradition has decreed that the great bulk of educated men shall know
at least the elements of the subject, the reasons for which the
tradition arose are forgotten, buried beneath a great rubbish-heap of
pedantries and trivialities. To those who inquire as to the purpose of
mathematics, the usual answer will be that it facilitates the making
of machines, the travelling from place to place, and the victory over
foreign nations, whether in war or commerce. If it be objected that
these ends, all of which are of doubtful value, are not furthered by
the merely elementary study imposed upon those who do not become
expert mathematicians, the reply, it is true, will probably be that
mathematics trains the reasoning faculties. Yet the very men who make
this reply are, for the most part, unwilling to abandon the teaching
of definite fallacies, known to be such, and instinctively rejected by
the unsophisticated mind of every intelligent learner.
And the reasoning faculty itself is generally conceived, by those who urge its cultivation, as merely a means for the avoidance of pitfalls and a help in the discovery of rules for the guidance of practical life. All these are undeniably important achievements to the credit of mathematics; yet it is none of these that entitles mathematics to a place in every liberal education. Plato, we know, regarded the contemplation of mathematical truths as worthy of the Deity; and Plato realised, more perhaps than any other single man, what those elements are in human life which merit a place in heaven. There is in mathematics, he says, "something which is necessary and cannot be set aside ... and, if I mistake not, of divine necessity; for as to the human necessities of which the Many talk in this connection, nothing can be more ridiculous than such an application of the words. Cleinias. And what are these necessities of knowledge, Stranger, which are divine and not human ? Athenian. Those things without some use or knowledge of which a man cannot become a God to the world, nor a spirit, nor yet a hero, nor able earnestly to think and care for man" (Laws, p. 818). Such was Plato's judgment of mathematics; but the mathematicians do not read Plato, while those who read him know no mathematics, and regard his opinion upon this question as merely a curious aberration.
And the reasoning faculty itself is generally conceived, by those who urge its cultivation, as merely a means for the avoidance of pitfalls and a help in the discovery of rules for the guidance of practical life. All these are undeniably important achievements to the credit of mathematics; yet it is none of these that entitles mathematics to a place in every liberal education. Plato, we know, regarded the contemplation of mathematical truths as worthy of the Deity; and Plato realised, more perhaps than any other single man, what those elements are in human life which merit a place in heaven. There is in mathematics, he says, "something which is necessary and cannot be set aside ... and, if I mistake not, of divine necessity; for as to the human necessities of which the Many talk in this connection, nothing can be more ridiculous than such an application of the words. Cleinias. And what are these necessities of knowledge, Stranger, which are divine and not human ? Athenian. Those things without some use or knowledge of which a man cannot become a God to the world, nor a spirit, nor yet a hero, nor able earnestly to think and care for man" (Laws, p. 818). Such was Plato's judgment of mathematics; but the mathematicians do not read Plato, while those who read him know no mathematics, and regard his opinion upon this question as merely a curious aberration.
Mathematics, rightly viewed, possesses not only truth, but supreme
beauty, a beauty cold and austere, like that of sculpture, without
appeal to any part of our weaker nature, without the gorgeous
trappings of painting or music, yet sublimely pure, and capable of a
stern perfection such as only the greatest art can show. The true
spirit of delight, the exaltation, the sense of being more than man,
which is the touchstone of the highest excellence, is to be found in
mathematics as surely as in poetry. What is best in mathematics
deserves not merely to be learnt as a task, but to be assimilated as a
part of daily thought, and brought again and again before the mind
with ever-renewed encouragement. Real life is, to most men, a long
second-best, a perpetual compromise between the ideal and the
possible; but the world of pure reason knows no compromise, no
practical limitations, no barrier to the creative activity embodying
in splendid edifices the passionate aspiration after the perfect from
which all great work springs. Remote from human passions, remote even
from the pitiful facts of nature, the generations have gradually
created an ordered cosmos, where pure thought can dwell as in its
natural home, and where one, at least, of our nobler impulses can
escape from the dreary exile of the actual world.
So little, however, have mathematicians aimed at beauty, that hardly
anything in their work has had this conscious purpose. Much, owing to
irrepressible instincts, which were better than avowed beliefs, has
been moulded by an unconscious taste; but much also has been spoilt by
false notions of what was fitting. The characteristic excellence of
mathematics is only to be found where the reasoning is rigidly
logical: the rules of logic are to mathematics what those of structure
are to architecture. In the most beautiful work, a chain of argument
is presented in which every link is important on its own account, in
which there is an air of ease and lucidity throughout, and the
premises achieve more than would have been thought possible, by means
which appear natural and inevitable. Literature embodies what is
general in particular circumstances whose universal significance
shines through their individual dress; but mathematics endeavours to
present whatever is most general in its purity, without any irrelevant
trappings.
How should the teaching of mathematics be conducted so as to
communicate to the learner as much as possible of this high ideal ?
Here experience must, in a great measure, be our guide; but some
maxims may result from our consideration of the ultimate purpose to be
achieved.
One of the chief ends served by mathematics, when rightly taught, is
to awaken the learner's belief in reason, his confidence in the truth
of what has been demonstrated, and in the value of demonstration. This
purpose is not served by existing instruction; but it is easy to see
ways in which it might be served. At present, in what concerns
arithmetic, the boy or girl is given a set of rules, which present
themselves as neither true nor false, but as merely the will of the
teacher, the way in which, for some unfathomable reason, the teacher
prefers to have the game played. To some degree, in a study of such
definite practical utility, this is no doubt unavoidable; but as soon
as possible, the reasons of rules should be set forth by whatever
means most readily appeal to the childish mind. In geometry, instead
of the tedious apparatus of fallacious proofs for obvious truisms
which constitutes the beginning of Euclid, the learner should be
allowed at first to assume the truth of everything obvious, and should
be instructed in the demonstrations of theorems which are at once
startling and easily verifiable by actual drawing, such as those in
which it is shown that three or more lines meet in a point.
In this way belief is generated; it is seen that reasoning may lead to startling conclusions, which nevertheless the facts will verify; and thus the instinctive distrust of whatever is abstract or rational is gradually overcome.
Where theorems are difficult, they should be first taught as exercises in geometrical drawing, until the figure has become thoroughly familiar; it will then be an agreeable advance to be taught the logical connections of the various lines or circles that occur. It is desirable also that the figure illustrating a theorem should be drawn in all possible cases and shapes, that so the abstract relations with which geometry is concerned may of themselves emerge as the residue of similarity amid such great apparent diversity. In this way the abstract demonstrations should form but a small part of the instruction, and should be given when, by familiarity with concrete illustrations, they have come to be felt as the natural embodiment of visible fact. In this early stage proofs should not be given with pedantic fullness; definitely fallacious methods, such as that of superposition, should be rigidly excluded from the first, but where, without such methods, the proof would be very difficult, the result should be rendered acceptable by arguments and illustrations which are explicitly contrasted with demonstrations.
In this way belief is generated; it is seen that reasoning may lead to startling conclusions, which nevertheless the facts will verify; and thus the instinctive distrust of whatever is abstract or rational is gradually overcome.
Where theorems are difficult, they should be first taught as exercises in geometrical drawing, until the figure has become thoroughly familiar; it will then be an agreeable advance to be taught the logical connections of the various lines or circles that occur. It is desirable also that the figure illustrating a theorem should be drawn in all possible cases and shapes, that so the abstract relations with which geometry is concerned may of themselves emerge as the residue of similarity amid such great apparent diversity. In this way the abstract demonstrations should form but a small part of the instruction, and should be given when, by familiarity with concrete illustrations, they have come to be felt as the natural embodiment of visible fact. In this early stage proofs should not be given with pedantic fullness; definitely fallacious methods, such as that of superposition, should be rigidly excluded from the first, but where, without such methods, the proof would be very difficult, the result should be rendered acceptable by arguments and illustrations which are explicitly contrasted with demonstrations.
In the beginning of algebra, even the most intelligent child finds, as
a rule, very great difficulty. The use of letters is a mystery, which
seems to have no purpose except mystification. It is almost
impossible, at first, not to think that every letter stands for some
particular number, if only the teacher would reveal what number it
stands for. The fact is, that in algebra the mind is first taught to
consider general truths, truths which are not asserted to hold only of
this or that particular thing, but of any one of a whole group of
things. It is in the power of understanding and discovering such
truths that the mastery of the intellect over the whole world of
things actual and possible resides; and ability to deal with the
general as such is one of the gifts that a mathematical education
should bestow. But how little, as a rule, is the teacher of algebra
able to explain the chasm which divides it from arithmetic, and how
little is the learner assisted in his groping efforts at
comprehension ! Usually the method that has been adopted in arithmetic
is continued: rules are set forth, with no adequate explanation of
their grounds; the pupil learns to use the rules blindly, and
presently, when he is able to obtain the answer that the teacher
desires, he feels that he has mastered the difficulties of the
subject. But of inner comprehension of the processes employed he has
probably acquired almost nothing.
When algebra has been learnt, all goes smoothly until we reach those
studies in which the notion of infinity is employed the infinitesimal
calculus and the whole of higher mathematics. The solution of the
difficulties which formerly surrounded the mathematical infinite is
probably the greatest achievement of which our own age has to boast.
Since the beginnings of Greek thought these difficulties have been
known; in every age the finest intellects have vainly endeavoured to
answer the apparently unanswerable questions that had been asked by
Zeno the Eleatic. At last Georg Cantor has found the answer, and has
conquered for the intellect a new and vast province which had been
given over to Chaos and old Night. It was assumed as self-evident,
until Cantor and Dedekind established the opposite, that if, from any
collection of things, some were taken away, the number of things left
must always be less than the original number of things. This
assumption, as a matter of fact, holds only of finite collections; and
the rejection of it, where the infinite is concerned, has been shown
to remove all the difficulties that had hitherto baffled human reason
in this matter, and to render possible the creation of an exact
science of the infinite. This stupendous fact ought to produce a
revolution in the higher teaching of mathematics; it has itself added
immeasurably to the educational value of the subject, and it has at
last given the means of treating with logical precision many studies
which, until lately, were wrapped in fallacy and obscurity. By those
who were educated on the old lines, the new work is considered to be
appallingly difficult, abstruse, and obscure; and it must be confessed
that the discoverer, as is so often the case, has hardly himself
emerged from the mists which the light of his intellect is dispelling.
But inherently, the new doctrine of the infinite, to all candid and
inquiring minds, has facilitated the mastery of higher mathematics;
for hitherto, it has been necessary to learn, by a long process of
sophistication, to give assent to arguments which, on first
acquaintance, were rightly judged to be confused and erroneous. So far
from producing a fearless belief in reason, a bold rejection of
whatever failed to fulfil the strictest requirements of logic, a
mathematical training, during the past two centuries, encouraged the
belief that many things, which a rigid inquiry would reject as
fallacious, must yet be accepted because they work in what the
mathematician calls "practice." By this means, a timid, compromising
spirit, or else a sacerdotal belief in mysteries not intelligible to
the profane, has been bred where reason alone should have ruled. All
this it is now time to sweep away; let those who wish to penetrate
into the arcana of mathematics be taught at once the true theory in
all its logical purity, and in the concatenation established by the
very essence of the entities concerned.
If we are considering mathematics as an end in itself, and not as a
technical training for engineers, it is very desirable to preserve the
purity and strictness of its reasoning. Accordingly those who have
attained a sufficient familiarity with its easier portions should be
led backward from propositions to which they have assented as
self-evident to more and more fundamental principles from which what
had previously appeared as premises can be deduced. They should be taught what the theory of infinity very aptly illustrates, that many
propositions seem self-evident to the untrained mind which,
nevertheless, a nearer scrutiny shows to be false.
By this means they will be led to a sceptical inquiry into first principles, an examination of the foundations upon which the whole edifice of reasoning is built, or, to take perhaps a more fitting metaphor, the great trunk from which the spreading branches spring. At this stage, it is well to study afresh the elementary portions of mathematics, asking no longer merely whether a given proposition is true, but also how it grows out of the central principles of logic. Questions of this nature can now be answered with a precision and certainty which were formerly quite impossible; and in the chains of reasoning that the answer requires the unity of all mathematical studies at last unfolds itself.
By this means they will be led to a sceptical inquiry into first principles, an examination of the foundations upon which the whole edifice of reasoning is built, or, to take perhaps a more fitting metaphor, the great trunk from which the spreading branches spring. At this stage, it is well to study afresh the elementary portions of mathematics, asking no longer merely whether a given proposition is true, but also how it grows out of the central principles of logic. Questions of this nature can now be answered with a precision and certainty which were formerly quite impossible; and in the chains of reasoning that the answer requires the unity of all mathematical studies at last unfolds itself.
In the great majority of mathematical text-books there is a total lack
of unity in method and of systematic development of a central theme.
Propositions of very diverse kinds are proved by whatever means are
thought most easily intelligible, and much space is devoted to mere
curiosities which in no way contribute to the main argument. But in
the greatest works, unity and inevitability are felt as in the
unfolding of a drama; in the premisses a subject is proposed for
consideration, and in every subsequent step some definite advance is
made towards mastery of its nature. The love of system, of
interconnection, which is perhaps the inmost essence of the
intellectual impulse, can find free play in mathematics as nowhere
else. The learner who feels this impulse must not be repelled by an
array of meaningless examples or distracted by amusing oddities, but
must be encouraged to dwell upon central principles, to become
familiar with the structure of the various subjects which are put
before him, to travel easily over the steps of the more important
deductions. In this way a good tone of mind is cultivated, and
selective attention is taught to dwell by preference upon what is
weighty and essential.
When the separate studies into which mathematics is divided have each
been viewed as a logical whole, as a natural growth from the
propositions which constitute their principles, the learner will be
able to understand the fundamental science which unifies and
systematises the whole of deductive reasoning. This is symbolic
logic, a study which, though it owes its inception to Aristotle, is
yet, in its wider developments, a product, almost wholly, of the
nineteenth century, and is indeed, in the present day, still growing
with great rapidity.
The true method of discovery in symbolic logic, and probably also the best method for introducing the study to a learner acquainted with other parts of mathematics, is the analysis of actual examples of deductive reasoning, with a view to the discovery of the principles employed. These principles, for the most part, are so embedded in our ratiocinative instincts, that they are employed quite unconsciously, and can be dragged to light only by much patient effort. But when at last they have been found, they are seen to be few in number, and to be the sole source of everything in pure mathematics. The discovery that all mathematics follows inevitably from a small collection of fundamental laws is one which immeasurably enhances the intellectual beauty of the whole; to those who have been oppressed by the fragmentary and incomplete nature of most existing chains of deduction this discovery comes with all the overwhelming force of a revelation; like a palace emerging from the autumn mist as the traveller ascends an Italian hill-side, the stately storeys of the mathematical edifice appear in their due order and proportion, with a new perfection in every part.
The true method of discovery in symbolic logic, and probably also the best method for introducing the study to a learner acquainted with other parts of mathematics, is the analysis of actual examples of deductive reasoning, with a view to the discovery of the principles employed. These principles, for the most part, are so embedded in our ratiocinative instincts, that they are employed quite unconsciously, and can be dragged to light only by much patient effort. But when at last they have been found, they are seen to be few in number, and to be the sole source of everything in pure mathematics. The discovery that all mathematics follows inevitably from a small collection of fundamental laws is one which immeasurably enhances the intellectual beauty of the whole; to those who have been oppressed by the fragmentary and incomplete nature of most existing chains of deduction this discovery comes with all the overwhelming force of a revelation; like a palace emerging from the autumn mist as the traveller ascends an Italian hill-side, the stately storeys of the mathematical edifice appear in their due order and proportion, with a new perfection in every part.
Until symbolic logic had acquired its present development, the
principles upon which mathematics depends were always supposed to be
philosophical, and discoverable only by the uncertain, unprogressive
methods hitherto employed by philosophers. So long as this was
thought, mathematics seemed to be not autonomous, but dependent upon a
study which had quite other methods than its own. Moreover, since the
nature of the postulates from which arithmetic, analysis, and geometry
are to be deduced was wrapped in all the traditional obscurities of
metaphysical discussion, the edifice built upon such dubious
foundations began to be viewed as no better than a castle in the air.
In this respect, the discovery that the true principles are as much a
part of mathematics as any of their consequences has very greatly
increased the intellectual satisfaction to be obtained. This
satisfaction ought not to be refused to learners capable of enjoying
it, for it is of a kind to increase our respect for human powers and
our knowledge of the beauties belonging to the abstract world.
Philosophers have commonly held that the laws of logic, which underlie
mathematics, are laws of thought, laws regulating the operations of
our minds. By this opinion the true dignity of reason is very greatly
lowered: it ceases to be an investigation into the very heart and
immutable essence of all things actual and possible, becoming,
instead, an inquiry into something more or less human and subject to
our limitations. The contemplation of what is non-human, the discovery
that our minds are capable of dealing with material not created by
them, above all, the realisation that beauty belongs to the outer
world as to the inner, are the chief means of overcoming the terrible
sense of impotence, of weakness, of exile amid hostile powers, which
is too apt to result from acknowledging the all-but omnipotence of
alien forces. To reconcile us, by the exhibition of its awful beauty,
to the reign of Fate which is merely the literary personification of
these forces is the task of tragedy. But mathematics takes us still
further from what is human, into the region of absolute necessity, to
which not only the actual world, but every possible world, must
conform; and even here it builds a habitation, or rather finds a
habitation eternally standing, where our ideals are fully satisfied
and our best hopes are not thwarted. It is only when we thoroughly
understand the entire independence of ourselves, which belongs to this
world that reason finds, that we can adequately realise the profound
importance of its beauty.
Not only is mathematics independent of us and our thoughts, but in
another sense we and the whole universe of existing things are
independent of mathematics. The apprehension of this purely ideal
character is indispensable, if we are to understand rightly the place
of mathematics as one among the arts. It was formerly supposed that
pure reason could decide, in some respects, as to the nature of the
actual world: geometry, at least, was thought to deal with the space
in which we live. But we now know that pure mathematics can never
pronounce upon questions of actual existence: the world of reason, in
a sense, controls the world of fact, but it is not at any point
creative of fact, and in the application of its results to the world
in time and space, its certainty and precision are lost among
approximations and working hypotheses. The objects considered by
mathematicians have, in the past, been mainly of a kind suggested by
phenomena; but from such restrictions the abstract imagination should
be wholly free. A reciprocal liberty must thus be accorded: reason
cannot dictate to the world of facts, but the facts cannot restrict
reason's privilege of dealing with whatever objects its love of beauty
may cause to seem worthy of consideration. Here, as elsewhere, we
build up our own ideals out of the fragments to be found in the world;
and in the end it is hard to say whether the result is a creation or a
discovery.
It is very desirable, in instruction, not merely to persuade the
student of the accuracy of important theorems, but to persuade him in
the way which itself has, of all possible ways, the most beauty. The
true interest of a demonstration is not, as traditional modes of
exposition suggest, concentrated wholly in the result; where this does
occur, it must be viewed as a defect, to be remedied, if possible, by
so generalising the steps of the proof that each becomes important in
and for itself. An argument which serves only to prove a conclusion is
like a story subordinated to some moral which it is meant to teach:
for æsthetic perfection no part of the whole should be merely a means.
A certain practical spirit, a desire for rapid progress, for conquest
of new realms, is responsible for the undue emphasis upon results
which prevails in mathematical instruction. The better way is to
propose some theme for consideration in geometry, a figure having
important properties; in analysis, a function of which the study is
illuminating, and so on. Whenever proofs depend upon some only of the
marks by which we define the object to be studied, these marks should
be isolated and investigated on their own account. For it is a defect,
in an argument, to employ more premisses than the conclusion demands:
what mathematicians call elegance results from employing only the
essential principles in virtue of which the thesis is true. It is a
merit in Euclid that he advances as far as he is able to go without
employing the axiom of parallels not, as is often said, because this
axiom is inherently objectionable, but because, in mathematics, every
new axiom diminishes the generality of the resulting theorems, and the
greatest possible generality is before all things to be sought.
Of the effects of mathematics outside its own sphere more has been
written than on the subject of its own proper ideal. The effect upon
philosophy has, in the past, been most notable, but most varied; in
the seventeenth century, idealism and rationalism, in the eighteenth,
materialism and sensationalism, seemed equally its offspring. Of the
effect which it is likely to have in the future it would be very rash
to say much; but in one respect a good result appears probable.
Against that kind of scepticism which abandons the pursuit of ideals
because the road is arduous and the goal not certainly attainable,
mathematics, within its own sphere, is a complete answer. Too often it
is said that there is no absolute truth, but only opinion and private
judgment; that each of us is conditioned, in his view of the world, by
his own peculiarities, his own taste and bias; that there is no
external kingdom of truth to which, by patience and discipline, we may
at last obtain admittance, but only truth for me, for you, for every
separate person. By this habit of mind one of the chief ends of human
effort is denied, and the supreme virtue of candour, of fearless
acknowledgment of what is, disappears from our moral vision. Of such
scepticism mathematics is a perpetual reproof; for its edifice of
truths stands unshakable and inexpungable to all the weapons of
doubting cynicism.
The effects of mathematics upon practical life, though they should not
be regarded as the motive of our studies, may be used to answer a
doubt to which the solitary student must always be liable. In a world
so full of evil and suffering, retirement into the cloister of
contemplation, to the enjoyment of delights which, however noble, must
always be for the few only, cannot but appear as a somewhat selfish
refusal to share the burden imposed upon others by accidents in which
justice plays no part. Have any of us the right, we ask, to withdraw
from present evils, to leave our fellow-men unaided, while we live a
life which, though arduous and austere, is yet plainly good in its own
nature? When these questions arise, the true answer is, no doubt, that
some must keep alive the sacred fire, some must preserve, in every
generation, the haunting vision which shadows forth the goal of so
much striving. But when, as must sometimes occur, this answer seems
too cold, when we are almost maddened by the spectacle of sorrows to
which we bring no help, then we may reflect that indirectly the
mathematician often does more for human happiness than any of his more
practically active contemporaries. The history of science abundantly
proves that a body of abstract propositions, even if, as in the case
of conic sections, it remains two thousand years without effect upon
daily life may yet, at any moment, be used to cause a revolution in
the habitual thoughts and occupations of every citizen. The use of
steam and electricity, to take striking instances, is rendered
possible only by mathematics. In the results of abstract thought the
world possesses a capital of which the employment in enriching the
common round has no hitherto discoverable limits. Nor does experience
give any means of deciding what parts of mathematics will be found
useful. Utility, therefore, can be only a consolation in moments of
discouragement, not a guide in directing our studies.
For the health of the moral life, for ennobling the tone of an age or
a nation, the austerer virtues have a strange power, exceeding the
power of those not informed and purified by thought. Of these austerer
virtues the love of truth is the chief, and in mathematics, more than
elsewhere, the love of truth may find encouragement for waning faith.
Every great study is not only an end in itself, but also a means of
creating and sustaining a lofty habit of mind; and this purpose should
be kept always in view throughout the teaching and learning of
mathematics.
V
MATHEMATICS AND THE METHAPHYSICIANS
The nineteenth century, which prided itself upon the invention of
steam and evolution, might have derived a more legitimate title to
fame from the discovery of pure mathematics. This science, like most
others, was baptised long before it was born; and thus we find writers
before the nineteenth century alluding to what they called pure
mathematics. But if they had been asked what this subject was, they
would only have been able to say that it consisted of Arithmetic,
Algebra, Geometry, and so on. As to what these studies had in common,
and as to what distinguished them from applied mathematics, our
ancestors were completely in the dark.
Pure mathematics was discovered by Boole, in a work which he called
the Laws of Thought (1854). This work abounds in asseverations that
it is not mathematical, the fact being that Boole was too modest to
suppose his book the first ever written on mathematics. He was also
mistaken in supposing that he was dealing with the laws of thought:
the question how people actually think was quite irrelevant to him,
and if his book had really contained the laws of thought, it was
curious that no one should ever have thought in such a way before. His
book was in fact concerned with formal logic, and this is the same
thing as mathematics.
Pure mathematics consists entirely of assertions to the effect that,
if such and such a proposition is true of anything, then such and
such another proposition is true of that thing. It is essential not to
discuss whether the first proposition is really true, and not to
mention what the anything is, of which it is supposed to be true. Both
these points would belong to applied mathematics. We start, in pure
mathematics, from certain rules of inference, by which we can infer
that if one proposition is true, then so is some other proposition.
These rules of inference constitute the major part of the principles
of formal logic. We then take any hypothesis that seems amusing, and
deduce its consequences. If our hypothesis is about anything, and
not about some one or more particular things, then our deductions
constitute mathematics. Thus mathematics may be defined as the subject
in which we never know what we are talking about, nor whether what we
are saying is true. People who have been puzzled by the beginnings of
mathematics will, I hope, find comfort in this definition, and will
probably agree that it is accurate.
As one of the chief triumphs of modern mathematics consists in having
discovered what mathematics really is, a few more words on this
subject may not be amiss. It is common to start any branch of
mathematics for instance, Geometry with a certain number of
primitive ideas, supposed incapable of definition, and a certain
number of primitive propositions or axioms, supposed incapable of
proof. Now the fact is that, though there are indefinables and
indemonstrables in every branch of applied mathematics, there are none
in pure mathematics except such as belong to general logic. Logic,
broadly speaking, is distinguished by the fact that its propositions
can be put into a form in which they apply to anything whatever. All
pure mathematics, Arithmetic, Analysis, and Geometry is built up by
combinations of the primitive ideas of logic, and its propositions are
deduced from the general axioms of logic, such as the syllogism and
the other rules of inference. And this is no longer a dream or an
aspiration. On the contrary, over the greater and more difficult part
of the domain of mathematics, it has been already accomplished; in the
few remaining cases, there is no special difficulty, and it is now
being rapidly achieved. Philosophers have disputed for ages whether
such deduction was possible; mathematicians have sat down and made the
deduction. For the philosophers there is now nothing left but graceful
acknowledgments.
The subject of formal logic, which has thus at last shown itself to be
identical with mathematics, was, as every one knows, invented by
Aristotle, and formed the chief study (other than theology) of the
Middle Ages. But Aristotle never got beyond the syllogism, which is a
very small part of the subject, and the schoolmen never got beyond
Aristotle. If any proof were required of our superiority to the
mediæval doctors, it might be found in this. Throughout the Middle
Ages, almost all the best intellects devoted themselves to formal
logic, whereas in the nineteenth century only an infinitesimal
proportion of the world's thought went into this subject.
Nevertheless, in each decade since 1850 more has been done to advance the subject than in the whole period from Aristotle to Leibniz. People have discovered how to make reasoning symbolic, as it is in Algebra, so that deductions are effected by mathematical rules. They have discovered many rules besides the syllogism, and a new branch of logic, called the Logic of Relatives, has been invented to deal with topics that wholly surpassed the powers of the old logic, though they form the chief contents of mathematics.
Nevertheless, in each decade since 1850 more has been done to advance the subject than in the whole period from Aristotle to Leibniz. People have discovered how to make reasoning symbolic, as it is in Algebra, so that deductions are effected by mathematical rules. They have discovered many rules besides the syllogism, and a new branch of logic, called the Logic of Relatives, has been invented to deal with topics that wholly surpassed the powers of the old logic, though they form the chief contents of mathematics.
It is not easy for the lay mind to realise the importance of symbolism
in discussing the foundations of mathematics, and the explanation may
perhaps seem strangely paradoxical. The fact is that symbolism is
useful because it makes things difficult. (This is not true of the
advanced parts of mathematics, but only of the beginnings.) What we
wish to know is, what can be deduced from what. Now, in the
beginnings, everything is self-evident; and it is very hard to see
whether one self-evident proposition follows from another or not.
Obviousness is always the enemy to correctness. Hence we invent some
new and difficult symbolism, in which nothing seems obvious. Then we
set up certain rules for operating on the symbols, and the whole thing
becomes mechanical. In this way we find out what must be taken as
premiss and what can be demonstrated or defined. For instance, the
whole of Arithmetic and Algebra has been shown to require three
indefinable notions and five indemonstrable propositions. But without
a symbolism it would have been very hard to find this out. It is so
obvious that two and two are four, that we can hardly make ourselves
sufficiently sceptical to doubt whether it can be proved. And the same
holds in other cases where self-evident things are to be proved.
But the proof of self-evident propositions may seem, to the
uninitiated, a somewhat frivolous occupation. To this we might reply
that it is often by no means self-evident that one obvious proposition
follows from another obvious proposition; so that we are really
discovering new truths when we prove what is evident by a method which
is not evident. But a more interesting retort is, that since people
have tried to prove obvious propositions, they have found that many of
them are false. Self-evidence is often a mere will-o'-the-wisp, which
is sure to lead us astray if we take it as our guide. For instance,
nothing is plainer than that a whole always has more terms than a
part, or that a number is increased by adding one to it. But these
propositions are now known to be usually false. Most numbers are
infinite, and if a number is infinite you may add ones to it as long
as you like without disturbing it in the least. One of the merits of a
proof is that it instils a certain doubt as to the result proved; and
when what is obvious can be proved in some cases, but not in others,
it becomes possible to suppose that in these other cases it is false.
The great master of the art of formal reasoning, among the men of our
own day, is an Italian, Professor Peano, of the University of
Turin. He has reduced the greater part of mathematics (and he or
his followers will, in time, have reduced the whole) to strict
symbolic form, in which there are no words at all. In the ordinary
mathematical books, there are no doubt fewer words than most readers
would wish. Still, little phrases occur, such as therefore, let us
assume, consider, or hence it follows. All these, however, are a
concession, and are swept away by Professor Peano. For instance, if we
wish to learn the whole of Arithmetic, Algebra, the Calculus, and
indeed all that is usually called pure mathematics (except Geometry),
we must start with a dictionary of three words. One symbol stands for
zero, another for number, and a third for next after. What these
ideas mean, it is necessary to know if you wish to become an
arithmetician. But after symbols have been invented for these three
ideas, not another word is required in the whole development. All
future symbols are symbolically explained by means of these three.
Even these three can be explained by means of the notions of
relation and class; but this requires the Logic of Relations,
which Professor Peano has never taken up. It must be admitted that
what a mathematician has to know to begin with is not much. There are
at most a dozen notions out of which all the notions in all pure
mathematics (including Geometry) are compounded. Professor Peano, who
is assisted by a very able school of young Italian disciples, has
shown how this may be done; and although the method which he has
invented is capable of being carried a good deal further than he has
carried it, the honour of the pioneer must belong to him.
Two hundred years ago, Leibniz foresaw the science which Peano has
perfected, and endeavoured to create it. He was prevented from
succeeding by respect for the authority of Aristotle, whom he could
not believe guilty of definite, formal fallacies; but the subject
which he desired to create now exists, in spite of the patronising
contempt with which his schemes have been treated by all superior
persons. From this "Universal Characteristic," as he called it, he
hoped for a solution of all problems, and an end to all disputes. "If
controversies were to arise," he says, "there would be no more need of
disputation between two philosophers than between two accountants. For
it would suffice to take their pens in their hands, to sit down to
their desks, and to say to each other (with a friend as witness, if
they liked), 'Let us calculate.'" This optimism has now appeared to be
somewhat excessive; there still are problems whose solution is
doubtful, and disputes which calculation cannot decide. But over an
enormous field of what was formerly controversial, Leibniz's dream has
become sober fact. In the whole philosophy of mathematics, which used
to be at least as full of doubt as any other part of philosophy, order
and certainty have replaced the confusion and hesitation which
formerly reigned. Philosophers, of course, have not yet discovered
this fact, and continue to write on such subjects in the old way. But
mathematicians, at least in Italy, have now the power of treating the
principles of mathematics in an exact and masterly manner, by means of
which the certainty of mathematics extends also to mathematical
philosophy. Hence many of the topics which used to be placed among the
great mysteries—for example, the natures of infinity, of continuity,
of space, time and motion are now no longer in any degree open to
doubt or discussion. Those who wish to know the nature of these things
need only read the works of such men as Peano or Georg Cantor; they
will there find exact and indubitable expositions of all these quondam
mysteries.
In this capricious world, nothing is more capricious than posthumous
fame. One of the most notable examples of posterity's lack of judgment
is the Eleatic Zeno. This man, who may be regarded as the founder of
the philosophy of infinity, appears in Plato's Parmenides in the
privileged position of instructor to Socrates. He invented four
arguments, all immeasurably subtle and profound, to prove that motion
is impossible, that Achilles can never overtake the tortoise, and that
an arrow in flight is really at rest. After being refuted by
Aristotle, and by every subsequent philosopher from that day to our
own, these arguments were reinstated, and made the basis of a
mathematical renaissance, by a German professor, who probably never
dreamed of any connection between himself and Zeno. Weierstrass,
by strictly banishing from mathematics the use of infinitesimals, has
at last shown that we live in an unchanging world, and that the arrow
in its flight is truly at rest. Zeno's only error lay in inferring (if
he did infer) that, because there is no such thing as a state of
change, therefore the world is in the same state at any one time as at
any other. This is a consequence which by no means follows; and in
this respect, the German mathematician is more constructive than the
ingenious Greek. Weierstrass has been able, by embodying his views in
mathematics, where familiarity with truth eliminates the vulgar
prejudices of common sense, to invest Zeno's paradoxes with the
respectable air of platitudes; and if the result is less delightful to
the lover of reason than Zeno's bold defiance, it is at any rate more
calculated to appease the mass of academic mankind.
Zeno was concerned, as a matter of fact, with three problems, each
presented by motion, but each more abstract than motion, and capable
of a purely arithmetical treatment. These are the problems of the
infinitesimal, the infinite, and continuity. To state clearly the
difficulties involved, was to accomplish perhaps the hardest part of
the philosopher's task. This was done by Zeno. From him to our own
day, the finest intellects of each generation in turn attacked the
problems, but achieved, broadly speaking, nothing. In our own time,
however, three men Weierstrass, Dedekind, and Cantor have not merely
advanced the three problems, but have completely solved them. The
solutions, for those acquainted with mathematics, are so clear as to
leave no longer the slightest doubt or difficulty. This achievement is
probably the greatest of which our age has to boast; and I know of no
age (except perhaps the golden age of Greece) which has a more
convincing proof to offer of the transcendent genius of its great men.
Of the three problems, that of the infinitesimal was solved by
Weierstrass; the solution of the other two was begun by Dedekind, and
definitively accomplished by Cantor.
The infinitesimal played formerly a great part in mathematics. It was
introduced by the Greeks, who regarded a circle as differing
infinitesimally from a polygon with a very large number of very small
equal sides. It gradually grew in importance, until, when Leibniz
invented the Infinitesimal Calculus, it seemed to become the
fundamental notion of all higher mathematics. Carlyle tells, in his
Frederick the Great, how Leibniz used to discourse to Queen Sophia
Charlotte of Prussia concerning the infinitely little, and how she
would reply that on that subject she needed no instruction the
behaviour of courtiers had made her thoroughly familiar with it. But
philosophers and mathematicians who for the most part had less
acquaintance with courts continued to discuss this topic, though
without making any advance. The Calculus required continuity, and
continuity was supposed to require the infinitely little; but nobody
could discover what the infinitely little might be. It was plainly not
quite zero, because a sufficiently large number of infinitesimals,
added together, were seen to make up a finite whole. But nobody could
point out any fraction which was not zero, and yet not finite. Thus
there was a deadlock. But at last Weierstrass discovered that the
infinitesimal was not needed at all, and that everything could be
accomplished without it. Thus there was no longer any need to suppose
that there was such a thing. Nowadays, therefore, mathematicians are
more dignified than Leibniz: instead of talking about the infinitely
small, they talk about the infinitely great, a subject which, however
appropriate to monarchs, seems, unfortunately, to interest them even
less than the infinitely little interested the monarchs to whom
Leibniz discoursed.
The banishment of the infinitesimal has all sorts of odd consequences,
to which one has to become gradually accustomed. For example, there is
no such thing as the next moment. The interval between one moment and
the next would have to be infinitesimal, since, if we take two moments
with a finite interval between them, there are always other moments in
the interval. Thus if there are to be no infinitesimals, no two
moments are quite consecutive, but there are always other moments
between any two. Hence there must be an infinite number of moments
between any two; because if there were a finite number one would be
nearest the first of the two moments, and therefore next to it. This
might be thought to be a difficulty; but, as a matter of fact, it is
here that the philosophy of the infinite comes in, and makes all
straight.
The same sort of thing happens in space. If any piece of matter be cut
in two, and then each part be halved, and so on, the bits will become
smaller and smaller, and can theoretically be made as small as we
please. However small they may be, they can still be cut up and made
smaller still. But they will always have some finite size, however
small they may be. We never reach the infinitesimal in this way, and
no finite number of divisions will bring us to points. Nevertheless
there are points, only these are not to be reached by successive
divisions. Here again, the philosophy of the infinite shows us how
this is possible, and why points are not infinitesimal lengths.
As regards motion and change, we get similarly curious results. People
used to think that when a thing changes, it must be in a state of
change, and that when a thing moves, it is in a state of motion. This
is now known to be a mistake. When a body moves, all that can be said
is that it is in one place at one time and in another at another. We
must not say that it will be in a neighbouring place at the next
instant, since there is no next instant. Philosophers often tell us
that when a body is in motion, it changes its position within the
instant. To this view Zeno long ago made the fatal retort that every
body always is where it is; but a retort so simple and brief was not
of the kind to which philosophers are accustomed to give weight, and
they have continued down to our own day to repeat the same phrases
which roused the Eleatic's destructive ardour. It was only recently
that it became possible to explain motion in detail in accordance with
Zeno's platitude, and in opposition to the philosopher's paradox. We
may now at last indulge the comfortable belief that a body in motion
is just as truly where it is as a body at rest. Motion consists merely
in the fact that bodies are sometimes in one place and sometimes in
another, and that they are at intermediate places at intermediate
times. Only those who have waded through the quagmire of philosophic
speculation on this subject can realise what a liberation from antique
prejudices is involved in this simple and straightforward commonplace.
The philosophy of the infinitesimal, as we have just seen, is mainly
negative. People used to believe in it, and now they have found out
their mistake. The philosophy of the infinite, on the other hand, is
wholly positive. It was formerly supposed that infinite numbers, and
the mathematical infinite generally, were self-contradictory. But as
it was obvious that there were infinities—for example, the number of
numbers—the contradictions of infinity seemed unavoidable, and
philosophy seemed to have wandered into a "cul-de-sac." This
difficulty led to Kant's antinomies, and hence, more or less
indirectly, to much of Hegel's dialectic method. Almost all current
philosophy is upset by the fact (of which very few philosophers are as
yet aware) that all the ancient and respectable contradictions in the
notion of the infinite have been once for all disposed of. The method
by which this has been done is most interesting and instructive. In
the first place, though people had talked glibly about infinity ever
since the beginnings of Greek thought, nobody had ever thought of
asking, What is infinity ? If any philosopher had been asked for a
definition of infinity, he might have produced some unintelligible
rigmarole, but he would certainly not have been able to give a
definition that had any meaning at all. Twenty years ago, roughly
speaking, Dedekind and Cantor asked this question, and, what is more
remarkable, they answered it. They found, that is to say, a perfectly
precise definition of an infinite number or an infinite collection of
things. This was the first and perhaps the greatest step. It then
remained to examine the supposed contradictions in this notion. Here
Cantor proceeded in the only proper way. He took pairs of
contradictory propositions, in which both sides of the contradiction
would be usually regarded as demonstrable, and he strictly examined
the supposed proofs. He found that all proofs adverse to infinity
involved a certain principle, at first sight obviously true, but
destructive, in its consequences, of almost all mathematics. The
proofs favourable to infinity, on the other hand, involved no
principle that had evil consequences. It thus appeared that common
sense had allowed itself to be taken in by a specious maxim, and that,
when once this maxim was rejected, all went well.
The maxim in question is, that if one collection is part of another,
the one which is a part has fewer terms than the one of which it is a
part. This maxim is true of finite numbers. For example, Englishmen
are only some among Europeans, and there are fewer Englishmen than
Europeans. But when we come to infinite numbers, this is no longer
true. This breakdown of the maxim gives us the precise definition of
infinity. A collection of terms is infinite when it contains as parts
other collections which have just as many terms as it has. If you can
take away some of the terms of a collection, without diminishing the
number of terms, then there are an infinite number of terms in the
collection. For example, there are just as many even numbers as there
are numbers altogether, since every number can be doubled. This may be
seen by putting odd and even numbers together in one row, and even
numbers alone in a row below:
1, 2, 3, 4, 5, ad infinitum.
2, 4, 6, 8, 10, ad infinitum.
2, 4, 6, 8, 10, ad infinitum.
There are obviously just as many numbers in the row below as in the
row above, because there is one below for each one above. This
property, which was formerly thought to be a contradiction, is now
transformed into a harmless definition of infinity, and shows, in the
above case, that the number of finite numbers is infinite.
But the uninitiated may wonder how it is possible to deal with a
number which cannot be counted. It is impossible to count up all the
numbers, one by one, because, however many we may count, there are
always more to follow. The fact is that counting is a very vulgar and
elementary way of finding out how many terms there are in a
collection. And in any case, counting gives us what mathematicians
call the ordinal number of our terms; that is to say, it arranges
our terms in an order or series, and its result tells us what type of
series results from this arrangement. In other words, it is impossible
to count things without counting some first and others afterwards, so
that counting always has to do with order. Now when there are only a
finite number of terms, we can count them in any order we like; but
when there are an infinite number, what corresponds to counting will
give us quite different results according to the way in which we carry
out the operation. Thus the ordinal number, which results from what,
in a general sense may be called counting, depends not only upon how
many terms we have, but also (where the number of terms is infinite)
upon the way in which the terms are arranged.
The fundamental infinite numbers are not ordinal, but are what is
called cardinal. They are not obtained by putting our terms in order
and counting them, but by a different method, which tells us, to begin
with, whether two collections have the same number of terms, or, if
not, which is the greater. It does not tell us, in the way in
which counting does, what number of terms a collection has; but if
we define a number as the number of terms in such and such a
collection, then this method enables us to discover whether some other
collection that may be mentioned has more or fewer terms. An
illustration will show how this is done. If there existed some country
in which, for one reason or another, it was impossible to take a
census, but in which it was known that every man had a wife and every
woman a husband, then (provided polygamy was not a national
institution) we should know, without counting, that there were exactly
as many men as there were women in that country, neither more nor less. This method can be applied generally. If there is some relation
which, like marriage, connects the things in one collection each with
one of the things in another collection, and vice versa, then the two
collections have the same number of terms. This was the way in which
we found that there are as many even numbers as there are numbers.
Every number can be doubled, and every even number can be halved, and
each process gives just one number corresponding to the one that is
doubled or halved. And in this way we can find any number of
collections each of which has just as many terms as there are finite
numbers. If every term of a collection can be hooked on to a number,
and all the finite numbers are used once, and only once, in the
process, then our collection must have just as many terms as there are
finite numbers. This is the general method by which the numbers of
infinite collections are defined.
But it must not be supposed that all infinite numbers are equal. On
the contrary, there are infinitely more infinite numbers than finite
ones. There are more ways of arranging the finite numbers in different
types of series than there are finite numbers. There are probably more
points in space and more moments in time than there are finite
numbers. There are exactly as many fractions as whole numbers,
although there are an infinite number of fractions between any two
whole numbers. But there are more irrational numbers than there are
whole numbers or fractions. There are probably exactly as many points
in space as there are irrational numbers, and exactly as many points
on a line a millionth of an inch long as in the whole of infinite
space.
There is a greatest of all infinite numbers, which is the number of things altogether, of every sort and kind. It is obvious that there cannot be a greater number than this, because, if everything has been taken, there is nothing left to add. Cantor has a proof that there is no greatest number, and if this proof were valid, the contradictions of infinity would reappear in a sublimated form. But in this one point, the master has been guilty of a very subtle fallacy, which I hope to explain in some future work.
There is a greatest of all infinite numbers, which is the number of things altogether, of every sort and kind. It is obvious that there cannot be a greater number than this, because, if everything has been taken, there is nothing left to add. Cantor has a proof that there is no greatest number, and if this proof were valid, the contradictions of infinity would reappear in a sublimated form. But in this one point, the master has been guilty of a very subtle fallacy, which I hope to explain in some future work.
We can now understand why Zeno believed that Achilles cannot overtake
the tortoise and why as a matter of fact he can overtake it. We shall
see that all the people who disagreed with Zeno had no right to do so,
because they all accepted premises from which his conclusion followed.
The argument is this: Let Achilles and the tortoise start along a road
at the same time, the tortoise (as is only fair) being allowed a
handicap. Let Achilles go twice as fast as the tortoise, or ten times
or a hundred times as fast. Then he will never reach the tortoise. For
at every moment the tortoise is somewhere and Achilles is somewhere;
and neither is ever twice in the same place while the race is going
on. Thus the tortoise goes to just as many places as Achilles does,
because each is in one place at one moment, and in another at any
other moment. But if Achilles were to catch up with the tortoise, the
places where the tortoise would have been would be only part of the
places where Achilles would have been. Here, we must suppose, Zeno
appealed to the maxim that the whole has more terms than the part.
Thus if Achilles were to overtake the tortoise, he would have been in
more places than the tortoise; but we saw that he must, in any period,
be in exactly as many places as the tortoise. Hence we infer that he
can never catch the tortoise. This argument is strictly correct, if we
allow the axiom that the whole has more terms than the part. As the
conclusion is absurd, the axiom must be rejected, and then all goes
well. But there is no good word to be said for the philosophers of the
past two thousand years and more, who have all allowed the axiom and
denied the conclusion.
The retention of this axiom leads to absolute contradictions, while
its rejection leads only to oddities. Some of these oddities, it must
be confessed, are very odd. One of them, which I call the paradox of
Tristram Shandy, is the converse of the Achilles, and shows that the
tortoise, if you give him time, will go just as far as Achilles.
Tristram Shandy, as we know, employed two years in chronicling the first two days of his life, and lamented that, at this rate, material would accumulate faster than he could deal with it, so that, as years went by, he would be farther and farther from the end of his history. Now I maintain that, if he had lived for ever, and had not wearied of his task, then, even if his life had continued as event fully as it began, no part of his biography would have remained unwritten. For consider: the hundredth day will be described in the hundredth year, the thousandth in the thousandth year, and so on. Whatever day we may choose as so far on that he cannot hope to reach it, that day will be described in the corresponding year. Thus any day that may be mentioned will be written up sooner or later, and therefore no part of the biography will remain permanently unwritten. This paradoxical but perfectly true proposition depends upon the fact that the number of days in all time is no greater than the number of years.
Tristram Shandy, as we know, employed two years in chronicling the first two days of his life, and lamented that, at this rate, material would accumulate faster than he could deal with it, so that, as years went by, he would be farther and farther from the end of his history. Now I maintain that, if he had lived for ever, and had not wearied of his task, then, even if his life had continued as event fully as it began, no part of his biography would have remained unwritten. For consider: the hundredth day will be described in the hundredth year, the thousandth in the thousandth year, and so on. Whatever day we may choose as so far on that he cannot hope to reach it, that day will be described in the corresponding year. Thus any day that may be mentioned will be written up sooner or later, and therefore no part of the biography will remain permanently unwritten. This paradoxical but perfectly true proposition depends upon the fact that the number of days in all time is no greater than the number of years.
Thus on the subject of infinity it is impossible to avoid conclusions
which at first sight appear paradoxical, and this is the reason why so
many philosophers have supposed that there were inherent
contradictions in the infinite. But a little practice enables one to
grasp the true principles of Cantor's doctrine, and to acquire new and
better instincts as to the true and the false. The oddities then
become no odder than the people at the antipodes, who used to be
thought impossible because they would find it so inconvenient to stand
on their heads.
The solution of the problems concerning infinity has enabled Cantor to
solve also the problems of continuity.
Of this, as of infinity, he has given a perfectly precise definition, and has shown that there are no contradictions in the notion so defined. But this subject is so technical that it is impossible to give any account of it here.
Of this, as of infinity, he has given a perfectly precise definition, and has shown that there are no contradictions in the notion so defined. But this subject is so technical that it is impossible to give any account of it here.
The notion of continuity depends upon that of order, since
continuity is merely a particular type of order. Mathematics has, in
modern times, brought order into greater and greater prominence. In
former days, it was supposed (and philosophers are still apt to
suppose) that quantity was the fundamental notion of mathematics. But
nowadays, quantity is banished altogether, except from one little
corner of Geometry, while order more and more reigns supreme. The
investigation of different kinds of series and their relations is now
a very large part of mathematics, and it has been found that this
investigation can be conducted without any reference to quantity, and,
for the most part, without any reference to number. All types of
series are capable of formal definition, and their properties can be
deduced from the principles of symbolic logic by means of the Algebra
of Relatives. The notion of a limit, which is fundamental in the
greater part of higher mathematics, used to be defined by means of
quantity, as a term to which the terms of some series approximate as
nearly as we please. But nowadays the limit is defined quite
differently, and the series which it limits may not approximate to it
at all. This improvement also is due to Cantor, and it is one which
has revolutionised mathematics. Only order is now relevant to limits.
Thus, for instance, the smallest of the infinite integers is the limit
of the finite integers, though all finite integers are at an infinite
distance from it. The study of different types of series is a general
subject of which the study of ordinal numbers (mentioned above) is a
special and very interesting branch. But the unavoidable
technicalities of this subject render it impossible to explain to any
but professed mathematicians.
Geometry, like Arithmetic, has been subsumed, in recent times, under
the general study of order. It was formerly supposed that Geometry was
the study of the nature of the space in which we live, and accordingly
it was urged, by those who held that what exists can only be known
empirically, that Geometry should really be regarded as belonging to
applied mathematics. But it has gradually appeared, by the increase of
non-Euclidean systems, that Geometry throws no more light upon the
nature of space than Arithmetic throws upon the population of the
United States. Geometry is a whole collection of deductive sciences
based on a corresponding collection of sets of axioms. One set of
axioms is Euclid's; other equally good sets of axioms lead to other
results. Whether Euclid's axioms are true, is a question as to which
the pure mathematician is indifferent; and, what is more, it is a
question which it is theoretically impossible to answer with certainty
in the affirmative. It might possibly be shown, by very careful
measurements, that Euclid's axioms are false; but no measurements
could ever assure us (owing to the errors of observation) that they
are exactly true. Thus the geometer leaves to the man of science to
decide, as best he may, what axioms are most nearly true in the actual
world. The geometer takes any set of axioms that seem interesting, and
deduces their consequences. What defines Geometry, in this sense, is
that the axioms must give rise to a series of more than one dimension.
And it is thus that Geometry becomes a department in the study of
order.
In Geometry, as in other parts of mathematics, Peano and his disciples
have done work of the very greatest merit as regards principles.
Formerly, it was held by philosophers and mathematicians alike that
the proofs in Geometry depended on the figure; nowadays, this is known
to be false. In the best books there are no figures at all. The
reasoning proceeds by the strict rules of formal logic from a set of
axioms laid down to begin with. If a figure is used, all sorts of
things seem obviously to follow, which no formal reasoning can prove
from the explicit axioms, and which, as a matter of fact, are only
accepted because they are obvious. By banishing the figure, it becomes
possible to discover all the axioms that are needed; and in this way
all sorts of possibilities, which would have otherwise remained
undetected, are brought to light.
One great advance, from the point of view of correctness, has been
made by introducing points as they are required, and not starting, as
was formerly done, by assuming the whole of space. This method is due
partly to Peano, partly to another Italian named Fano. To those
unaccustomed to it, it has an air of somewhat wilful pedantry. In this
way, we begin with the following axioms: (1) There is a class of
entities called points. (2)
There is at least one point. If a be a point, there is at least one other point besides a. Then we bring in the straight line joining two points, and begin again with , namely, on the straight line joining a and b, there is at least one other point besides a and b. There is at least one point not on the line ab. And so we go on, till we have the means of obtaining as many points as we require. But the word space, as Peano humorously remarks, is one for which Geometry has no use at all.
There is at least one point. If a be a point, there is at least one other point besides a. Then we bring in the straight line joining two points, and begin again with , namely, on the straight line joining a and b, there is at least one other point besides a and b. There is at least one point not on the line ab. And so we go on, till we have the means of obtaining as many points as we require. But the word space, as Peano humorously remarks, is one for which Geometry has no use at all.
The rigid methods employed by modern geometers have deposed Euclid
from his pinnacle of correctness. It was thought, until recent times,
that, as Sir Henry Savile remarked in 1621, there were only two
blemishes in Euclid, the theory of parallels and the theory of
proportion. It is now known that these are almost the only points in
which Euclid is free from blemish. Countless errors are involved in
his first eight propositions. That is to say, not only is it doubtful
whether his axioms are true, which is a comparatively trivial matter,
but it is certain that his propositions do not follow from the axioms
which he enunciates. A vastly greater number of axioms, which Euclid
unconsciously employs, are required for the proof of his propositions.
Even in the first proposition of all, where he constructs an
equilateral triangle on a given base, he uses two circles which are
assumed to intersect. But no explicit axiom assures us that they do
so, and in some kinds of spaces they do not always intersect. It is
quite doubtful whether our space belongs to one of these kinds or not.
Thus Euclid fails entirely to prove his point in the very first
proposition. As he is certainly not an easy author, and is terribly
long-winded, he has no longer any but an historical interest. Under
these circumstances, it is nothing less than a scandal that he should
still be taught to boys in England. A book should have either
intelligibility or correctness; to combine the two is impossible, but
to lack both is to be unworthy of such a place as Euclid has occupied
in education.
The most remarkable result of modern methods in mathematics is the
importance of symbolic logic and of rigid formalism. Mathematicians,
under the influence of Weierstrass, have shown in modern times a care
for accuracy, and an aversion to slipshod reasoning, such as had not
been known among them previously since the time of the Greeks. The
great inventions of the seventeenth century, Analytical Geometry and
the Infinitesimal Calculus, were so fruitful in new results that
mathematicians had neither time nor inclination to examine their
foundations. Philosophers, who should have taken up the task, had too
little mathematical ability to invent the new branches of mathematics
which have now been found necessary for any adequate discussion. Thus
mathematicians were only awakened from their "dogmatic slumbers" when
Weierstrass and his followers showed that many of their most cherished
propositions are in general false. Macaulay, contrasting the certainty
of mathematics with the uncertainty of philosophy, asks who ever heard
of a reaction against Taylor's theorem ? If he had lived now, he
himself might have heard of such a reaction, for this is precisely one
of the theorems which modern investigations have overthrown. Such rude
shocks to mathematical faith have produced that love of formalism
which appears, to those who are ignorant of its motive, to be mere
outrageous pedantry.
The proof that all pure mathematics, including Geometry, is nothing
but formal logic, is a fatal blow to the Kantian philosophy. Kant,
rightly perceiving that Euclid's propositions could not be deduced
from Euclid's axioms without the help of the figures, invented a
theory of knowledge to account for this fact; and it accounted so
successfully that, when the fact is shown to be a mere defect in
Euclid, and not a result of the nature of geometrical reasoning,
Kant's theory also has to be abandoned. The whole doctrine of a
priori intuitions, by which Kant explained the possibility of pure
mathematics, is wholly inapplicable to mathematics in its present
form. The Aristotelian doctrines of the schoolmen come nearer in
spirit to the doctrines which modern mathematics inspire; but the
schoolmen were hampered by the fact that their formal logic was very
defective, and that the philosophical logic based upon the syllogism
showed a corresponding narrowness. What is now required is to give the
greatest possible development to mathematical logic, to allow to the
full the importance of relations, and then to found upon this secure
basis a new philosophical logic, which may hope to borrow some of the
exactitude and certainty of its mathematical foundation. If this can
be successfully accomplished, there is every reason to hope that the
near future will be as great an epoch in pure philosophy as the
immediate past has been in the principles of mathematics. Great
triumphs inspire great hopes; and pure thought may achieve, within our
generation, such results as will place our time, in this respect, on a
level with the greatest age of Greece.
VI
ON SCIENTIFIC METHOD IN PHILOSOPHY
When we try to ascertain the motives which have led men to the
investigation of philosophical questions, we find that, broadly
speaking, they can be divided into two groups, often antagonistic, and
leading to very divergent systems. These two groups of motives are, on
the one hand, those derived from religion and ethics, and, on the
other hand, those derived from science. Plato, Spinoza, and Hegel may
be taken as typical of the philosophers whose interests are mainly
religious and ethical, while Leibniz, Locke, and Hume may be taken as
representatives of the scientific wing. In Aristotle, Descartes,
Berkeley, and Kant we find both groups of motives strongly present.
Herbert Spencer, in whose honour we are assembled today, would
naturally be classed among scientific philosophers: it was mainly from
science that he drew his data, his formulation of problems, and his
conception of method. But his strong religious sense is obvious in
much of his writing, and his ethical pre-occupations are what make him
value the conception of evolution, that conception in which, as a
whole generation has believed, science and morals are to be united in
fruitful and indissoluble marriage.
It is my belief that the ethical and religious motives in spite of
the splendidly imaginative systems to which they have given rise, have
been on the whole a hindrance to the progress of philosophy, and ought
now to be consciously thrust aside by those who wish to discover
philosophical truth. Science, originally, was entangled in similar
motives, and was thereby hindered in its advances. It is, I maintain,
from science, rather than from ethics and religion, that philosophy
should draw its inspiration.
But there are two different ways in which a philosophy may seek to
base itself upon science. It may emphasise the most general results
of science, and seek to give even greater generality and unity to
these results. Or it may study the methods of science, and seek to
apply these methods, with the necessary adaptations, to its own
peculiar province. Much philosophy inspired by science has gone astray
through preoccupation with the results momentarily supposed to have
been achieved. It is not results, but methods that can be
transferred with profit from the sphere of the special sciences to the
sphere of philosophy. What I wish to bring to your notice is the
possibility and importance of applying to philosophical problems
certain broad principles of method which have been found successful in
the study of scientific questions.
The opposition between a philosophy guided by scientific method and a
philosophy dominated by religious and ethical ideas may be illustrated
by two notions which are very prevalent in the works of philosophers,
namely the notion of the universe, and the notion of good and
evil. A philosopher is expected to tell us something about the nature
of the universe as a whole, and to give grounds for either optimism or
pessimism. Both these expectations seem to me mistaken. I believe the
conception of "the universe" to be, as its etymology indicates, a mere relic of pre-Copernican astronomy: and I believe the question of
optimism and pessimism to be one which the philosopher will regard as
outside his scope, except, possibly, to the extent of maintaining that
it is insoluble.
In the days before Copernicus, the conception of the "universe" was
defensible on scientific grounds: the diurnal revolution of the
heavenly bodies bound them together as all parts of one system, of
which the earth was the centre. Round this apparent scientific fact,
many human desires rallied: the wish to believe Man important in the
scheme of things, the theoretical desire for a comprehensive
understanding of the Whole, the hope that the course of nature might
be guided by some sympathy with our wishes. In this way, an ethically
inspired system of metaphysics grew up, whose anthropocentrism was
apparently warranted by the geocentrism of astronomy. When Copernicus
swept away the astronomical basis of this system of thought, it had
grown so familiar, and had associated itself so intimately with men's
aspirations, that it survived with scarcely diminished force survived
even Kant's "Copernican revolution," and is still now the unconscious
premiss of most metaphysical systems.
The oneness of the world is an almost undiscussed postulate of most
metaphysics. "Reality is not merely one and self-consistent, but is a
system of reciprocally determinate parts", such a statement would
pass almost unnoticed as a mere truism. Yet I believe that it embodies
a failure to effect thoroughly the "Copernican revolution," and that
the apparent oneness of the world is merely the oneness of what is
seen by a single spectator or apprehended by a single mind. The
Critical Philosophy, although it intended to emphasise the subjective
element in many apparent characteristics of the world, yet, by
regarding the world in itself as unknowable, so concentrated attention
upon the subjective representation that its subjectivity was soon
forgotten. Having recognised the categories as the work of the mind,
it was paralysed by its own recognition, and abandoned in despair the
attempt to undo the work of subjective falsification. In part, no
doubt, its despair was well founded, but not, I think, in any absolute
or ultimate sense. Still less was it a ground for rejoicing, or for
supposing that the nescience to which it ought to have given rise
could be legitimately exchanged for a metaphysical dogmatism.
I
As regards our present question, namely, the question of the unity of
the world, the right method, as I think, has been indicated by William
James. "Let us now turn our backs upon ineffable or unintelligible
ways of accounting for the world's oneness, and inquire whether,
instead of being a principle, the 'oneness' affirmed may not merely be
a name like 'substance' descriptive of the fact that certain specific
and verifiable connections are found among the parts of the
experiential flux.... We can easily conceive of things that shall have
no connection whatever with each other. We may assume them to inhabit
different times and spaces, as the dreams of different persons do even
now. They may be so unlike and incommensurable, and so inert towards
one another, as never to jostle or interfere. Even now there may
actually be whole universes so disparate from ours that we who know
ours have no means of perceiving that they exist. We conceive their
diversity, however; and by that fact the whole lot of them form what
is known in logic as 'a universe of discourse.' To form a universe of
discourse argues, as this example shows, no further kind of connexion.
The importance attached by certain monistic writers to the fact that
any chaos may become a universe by merely being named, is to me
incomprehensible." We are thus left with two kinds of unity in the
experienced world; the one what we may call the epistemological unity,
due merely to the fact that my experienced world is what one
experience selects from the sum total of existence: the other that
tentative and partial unity exhibited in the prevalence of scientific
laws in those portions of the world which science has hitherto
mastered. Now a generalisation based upon either of these kinds of
unity would be fallacious. That the things which we experience have
the common property of being experienced by us is a truism from which
obviously nothing of importance can be deducible: it is clearly
fallacious to draw from the fact that whatever we experience is
experienced the conclusion that therefore everything must be
experienced. The generalisation of the second kind of unity, namely,
that derived from scientific laws, would be equally fallacious, though
the fallacy is a trifle less elementary. In order to explain it let us
consider for a moment what is called the reign of law. People often
speak as though it were a remarkable fact that the physical world is
subject to invariable laws. In fact, however, it is not easy to see
how such a world could fail to obey general laws. Taking any arbitrary
set of points in space, there is a function of the time corresponding
to these points, i.e. expressing the motion of a particle which
traverses these points: this function may be regarded as a general law
to which the behaviour of such a particle is subject. Taking all such
functions for all the particles in the universe, there will be
theoretically some one formula embracing them all, and this formula
may be regarded as the single and supreme law of the spatio-temporal
world. Thus what is surprising in physics is not the existence of
general laws, but their extreme simplicity. It is not the uniformity
of nature that should surprise us, for, by sufficient analytic
ingenuity, any conceivable course of nature might be shown to exhibit
uniformity. What should surprise us is the fact that the uniformity is
simple enough for us to be able to discover it. But it is just this
characteristic of simplicity in the laws of nature hitherto discovered
which it would be fallacious to generalise, for it is obvious that
simplicity has been a part cause of their discovery, and can,
therefore, give no ground for the supposition that other undiscovered
laws are equally simple.
The fallacies to which these two kinds of unity have given rise
suggest a caution as regards all use in philosophy of general
results that science is supposed to have achieved. In the first
place, in generalising these results beyond past experience, it is
necessary to examine very carefully whether there is not some reason
making it more probable that these results should hold of all that has
been experienced than that they should hold of things universally. The
sum total of what is experienced by mankind is a selection from the
sum total of what exists, and any general character exhibited by this
selection may be due to the manner of selecting rather than to the
general character of that from which experience selects. In the second
place, the most general results of science are the least certain and
the most liable to be upset by subsequent research. In utilizing these
results as the basis of a philosophy, we sacrifice the most valuable
and remarkable characteristic of scientific method, namely, that,
although almost everything in science is found sooner or later to
require some correction, yet this correction is almost always such as
to leave untouched, or only slightly modified, the greater part of the
results which have been deduced from the premiss subsequently
discovered to be faulty. The prudent man of science acquires a certain
instinct as to the kind of uses which may be made of present
scientific beliefs without incurring the danger of complete and utter
refutation from the modifications likely to be introduced by
subsequent discoveries. Unfortunately the use of scientific
generalisations of a sweeping kind as the basis of philosophy is just
that kind of use which an instinct of scientific caution would avoid,
since, as a rule, it would only lead to true results if the
generalisation upon which it is based stood in no need of
correction.
We may illustrate these general considerations by means of two
examples, namely, the conservation of energy and the principle of
evolution.
Let us begin with the conservation of energy, or, as Herbert
Spencer used to call it, the persistence of force. He says:
"Before taking a first step in the rational interpretation of
Evolution, it is needful to recognise, not only the facts that
Matter is indestructible and Motion continuous, but also the fact
that Force persists. An attempt to assign the causes of
Evolution would manifestly be absurd if that agency to which the
metamorphosis in general and in detail is due, could either come
into existence or cease to exist. The succession of phenomena
would in such case be altogether arbitrary, and deductive Science
impossible."
This paragraph illustrates the kind of way in which the philosopher is
tempted to give an air of absoluteness and necessity to empirical
generalisations, of which only the approximate truth in the regions
hitherto investigated can be guaranteed by the unaided methods of
science. It is very often said that the persistence of something or
other is a necessary presupposition of all scientific investigation,
and this presupposition is then thought to be exemplified in some
quantity which physics declares to be constant. There are here, as it
seems to me, three distinct errors. First, the detailed scientific
investigation of nature does not presuppose any such general laws as
its results are found to verify. Apart from particular observations,
science need presuppose nothing except the general principles of
logic, and these principles are not laws of nature, for they are
merely hypothetical, and apply not only to the actual world but to
whatever is possible. The second error consists in the
identification of a constant quantity with a persistent entity. Energy
is a certain function of a physical system, but is not a thing or
substance persisting throughout the changes of the system. The same is
true of mass, in spite of the fact that mass has often been defined as
quantity of matter. The whole conception of quantity, involving, as
it does, numerical measurement based largely upon conventions, is far
more artificial, far more an embodiment of mathematical convenience,
than is commonly believed by those who philosophise on physics. Thus
even if (which I cannot for a moment admit) the persistence of some
entity were among the necessary postulates of science, it would be a
sheer error to infer from this the constancy of any physical quantity,
or the a priori necessity of any such constancy which may be
empirically discovered. In the third place, it has become more and
more evident with the progress of physics that large generalisations,
such as the conservation of energy or mass, are far from certain and
are very likely only approximate. Mass, which used to be regarded as
the most indubitable of physical quantities, is now generally believed
to vary according to velocity, and to be, in fact, a vector quantity
which at a given moment is different in different directions.
The detailed conclusions deduced from the supposed constancy of mass for such motions as used to be studied in physics will remain very nearly exact, and therefore over the field of the older investigations very little modification of the older results is required. But as soon as such a principle as the conservation of mass or of energy is erected into a universal a priori law, the slightest failure in absolute exactness is fatal, and the whole philosophic structure raised upon this foundation is necessarily ruined. The prudent philosopher, therefore, though he may with advantage study the methods of physics, will be very chary of basing anything upon what happen at the moment to be the most general results apparently obtained by those methods.
The detailed conclusions deduced from the supposed constancy of mass for such motions as used to be studied in physics will remain very nearly exact, and therefore over the field of the older investigations very little modification of the older results is required. But as soon as such a principle as the conservation of mass or of energy is erected into a universal a priori law, the slightest failure in absolute exactness is fatal, and the whole philosophic structure raised upon this foundation is necessarily ruined. The prudent philosopher, therefore, though he may with advantage study the methods of physics, will be very chary of basing anything upon what happen at the moment to be the most general results apparently obtained by those methods.
The philosophy of evolution, which was to be our second example,
illustrates the same tendency to hasty generalisation, and also
another sort, namely, the undue preoccupation with ethical notions.
There are two kinds of evolutionist philosophy, of which both Hegel
and Spencer represent the older and less radical kind, while
Pragmatism and Bergson represent the more modern and revolutionary
variety. But both these sorts of evolutionism have in common the
emphasis on progress, that is, upon a continual change from the
worse to the better, or from the simpler to the more complex. It would be unfair to attribute to Hegel any scientific motive or
foundation, but all the other evolutionists, including Hegel's modern
disciples, have derived their impetus very largely from the history of
biological development. To a philosophy which derives a law of
universal progress from this history there are two objections. First,
that this history itself is concerned with a very small selection of
facts confined to an infinitesimal fragment of space and time, and
even on scientific grounds probably not an average sample of events in
the world at large. For we know that decay as well as growth is a
normal occurrence in the world. An extra-terrestrial philosopher, who
had watched a single youth up to the age of twenty-one and had never
come across any other human being, might conclude that it is the
nature of human beings to grow continually taller and wiser in an
indefinite progress towards perfection; and this generalisation would
be just as well founded as the generalisation which evolutionists base
upon the previous history of this planet. Apart, however, from this
scientific objection to evolutionism, there is another, derived from
the undue admixture of ethical notions in the very idea of progress
from which evolutionism derives its charm. Organic life, we are told,
has developed gradually from the protozoon to the philosopher, and
this development, we are assured, is indubitably an advance.
Unfortunately it is the philosopher, not the protozoon, who gives us
this assurance, and we can have no security that the impartial
outsider would agree with the philosopher's self-complacent
assumption. This point has been illustrated by the philosopher Chuang
Tzŭ in the following instructive anecdote:
"The Grand Augur, in his ceremonial robes, approached the shambles
and thus addressed the pigs: 'How can you object to die ? I shall
fatten you for three months. I shall discipline myself for ten
days and fast for three. I shall strew fine grass, and place you
bodily upon a carved sacrificial dish. Does not this satisfy you ?'
Then, speaking from the pigs' point of view, he continued: 'It is
better, perhaps, after all, to live on bran and escape the
shambles....'
'But then,' added he, speaking from his own point of view, 'to
enjoy honour when alive one would readily die on a war-shield or
in the headsman's basket.'
So he rejected the pigs' point of view and adopted his own point
of view. In what sense, then, was he different from the pigs ?"
I much fear that the evolutionists too often resemble the Grand Augur
and the pigs.
The ethical element which has been prominent in many of the most
famous systems of philosophy is, in my opinion, one of the most
serious obstacles to the victory of scientific method in the
investigation of philosophical questions. Human ethical notions, as
Chuang Tzŭ perceived, are essentially anthropocentric, and involve,
when used in metaphysics, an attempt, however veiled, to legislate for
the universe on the basis of the present desires of men. In this way
they interfere with that receptivity to fact which is the essence of
the scientific attitude towards the world. To regard ethical notions
as a key to the understanding of the world is essentially
pre-Copernican. It is to make man, with the hopes and ideals which he
happens to have at the present moment, the centre of the universe and
the interpreter of its supposed aims and purposes. Ethical metaphysics
is fundamentally an attempt, however disguised, to give legislative
force to our own wishes. This may, of course, be questioned, but I
think that it is confirmed by a consideration of the way in which
ethical notions arise. Ethics is essentially a product of the
gregarious instinct, that is to say, of the instinct to co-operate
with those who are to form our own group against those who belong to
other groups. Those who belong to our own group are good; those who
belong to hostile groups are wicked. The ends which are pursued by our
own group are desirable ends, the ends pursued by hostile groups are
nefarious. The subjectivity of this situation is not apparent to the
gregarious animal, which feels that the general principles of justice
are on the side of its own herd. When the animal has arrived at the
dignity of the metaphysician, it invents ethics as the embodiment of
its belief in the justice of its own herd. So the Grand Augur invokes
ethics as the justification of Augurs in their conflicts with pigs.
But, it may be said, this view of ethics takes no account of such
truly ethical notions as that of self-sacrifice. This, however, would
be a mistake. The success of gregarious animals in the struggle for
existence depends upon co-operation within the herd, and co-operation
requires sacrifice, to some extent, of what would otherwise be the
interest of the individual. Hence arises a conflict of desires and
instincts, since both self-preservation and the preservation of the
herd are biological ends to the individual. Ethics is in origin the
art of recommending to others the sacrifices required for co-operation
with oneself. Hence, by reflexion, it comes, through the operation of
social justice, to recommend sacrifices by oneself, but all ethics,
however refined, remains more or less subjective. Even vegetarians do
not hesitate, for example, to save the life of a man in a fever,
although in doing so they destroy the lives of many millions of
microbes. The view of the world taken by the philosophy derived from
ethical notions is thus never impartial and therefore never fully
scientific. As compared with science, it fails to achieve the
imaginative liberation from self which is necessary to such
understanding of the world as man can hope to achieve, and the
philosophy which it inspires is always more or less parochial, more or
less infected with the prejudices of a time and a place.
I do not deny the importance or value, within its own sphere, of the
kind of philosophy which is inspired by ethical notions. The ethical
work of Spinoza, for example, appears to me of the very highest
significance, but what is valuable in such work is not any
metaphysical theory as to the nature of the world to which it may give
rise, nor indeed anything which can be proved or disproved by
argument. What is valuable is the indication of some new way of
feeling towards life and the world, some way of feeling by which our
own existence can acquire more of the characteristics which we must
deeply desire. The value of such work, however immeasurable it is,
belongs with practice and not with theory. Such theoretic importance
as it may possess is only in relation to human nature, not in relation
to the world at large. The scientific philosophy, therefore, which
aims only at understanding the world and not directly at any other
improvement of human life, cannot take account of ethical notions
without being turned aside from that submission to fact which is the
essence of the scientific temper.
II
If the notion of the universe and the notion of good and evil are
extruded from scientific philosophy, it may be asked what specific
problems remain for the philosopher as opposed to the man of science?
It would be difficult to give a precise answer to this question, but
certain characteristics may be noted as distinguishing the province of
philosophy from that of the special sciences.
In the first place a philosophical proposition must be general. It
must not deal specially with things on the surface of the earth, or
with the solar system, or with any other portion of space and time. It
is this need of generality which has led to the belief that philosophy
deals with the universe as a whole. I do not believe that this belief
is justified, but I do believe that a philosophical proposition must
be applicable to everything that exists or may exist. It might be
supposed that this admission would be scarcely distinguishable from
the view which I wish to reject. This, however, would be an error, and
an important one. The traditional view would make the universe itself
the subject of various predicates which could not be applied to any
particular thing in the universe, and the ascription of such peculiar
predicates to the universe would be the special business of
philosophy. I maintain, on the contrary, that there are no
propositions of which the "universe" is the subject; in other words,
that there is no such thing as the "universe." What I do maintain is
that there are general propositions which may be asserted of each
individual thing, such as the propositions of logic. This does not
involve that all the things there are form a whole which could be
regarded as another thing and be made the subject of predicates. It
involves only the assertion that there are properties which belong to
each separate thing, not that there are properties belonging to the
whole of things collectively. The philosophy which I wish to advocate
may be called logical atomism or absolute pluralism, because, while
maintaining that there are many things, it denies that there is a
whole composed of those things. We shall see, therefore, that
philosophical propositions, instead of being concerned with the whole
of things collectively, are concerned with all things distributively;
and not only must they be concerned with all things, but they must be
concerned with such properties of all things as do not depend upon the
accidental nature of the things that there happen to be, but are true
of any possible world, independently of such facts as can only be
discovered by our senses.
This brings us to a second characteristic of philosophical
propositions, namely, that they must be a priori. A philosophical
proposition must be such as can be neither proved nor disproved by
empirical evidence. Too often we find in philosophical books arguments
based upon the course of history, or the convolutions of the brain, or
the eyes of shell-fish. Special and accidental facts of this kind are
irrelevant to philosophy, which must make only such assertions as
would be equally true however the actual world were constituted.
We may sum up these two characteristics of philosophical propositions
by saying that philosophy is the science of the possible. But this
statement unexplained is liable to be misleading, since it may be
thought that the possible is something other than the general, whereas
in fact the two are indistinguishable.
Philosophy, if what has been said is correct, becomes
indistinguishable from logic as that word has now come to be used.
The study of logic consists, broadly speaking, of two not very sharply
distinguished portions. On the one hand it is concerned with those
general statements which can be made concerning everything without
mentioning any one thing or predicate or relation, such for example as
"if x is a member of the class α and every member of α
is a member of β, then x is a member of the class
β, whatever x, α, and β may
be." On the other hand, it is concerned with the analysis and
enumeration of logical forms, i.e. with the kinds of propositions
that may occur, with the various types of facts, and with the
classification of the constituents of facts. In this way logic
provides an inventory of possibilities, a repertory of abstractly
tenable hypotheses.
It might be thought that such a study would be too vague and too
general to be of any very great importance, and that, if its problems
became at any point sufficiently definite, they would be merged in the
problems of some special science. It appears, however, that this is
not the case. In some problems, for example, the analysis of space and
time, the nature of perception, or the theory of judgment, the
discovery of the logical form of the facts involved is the hardest
part of the work and the part whose performance has been most lacking
hitherto. It is chiefly for want of the right logical hypothesis that
such problems have hitherto been treated in such an unsatisfactory
manner, and have given rise to those contradictions or antinomies in
which the enemies of reason among philosophers have at all times
delighted.
By concentrating attention upon the investigation of logical forms, it
becomes possible at last for philosophy to deal with its problems
piecemeal, and to obtain, as the sciences do, such partial and
probably not wholly correct results as subsequent investigation can
utilise even while it supplements and improves them. Most
philosophies hitherto have been constructed all in one block, in such
a way that, if they were not wholly correct, they were wholly
incorrect, and could not be used as a basis for further
investigations. It is chiefly owing to this fact that philosophy,
unlike science, has hitherto been unprogressive, because each original
philosopher has had to begin the work again from the beginning,
without being able to accept anything definite from the work of his
predecessors. A scientific philosophy such as I wish to recommend will
be piecemeal and tentative like other sciences; above all, it will be
able to invent hypotheses which, even if they are not wholly true,
will yet remain fruitful after the necessary corrections have been
made. This possibility of successive approximations to the truth is,
more than anything else, the source of the triumphs of science, and to
transfer this possibility to philosophy is to ensure a progress in
method whose importance it would be almost impossible to exaggerate.
The essence of philosophy as thus conceived is analysis, not
synthesis. To build up systems of the world, like Heine's German
professor who knit together fragments of life and made an intelligible
system out of them, is not, I believe, any more feasible than the
discovery of the philosopher's stone. What is feasible is the
understanding of general forms, and the division of traditional
problems into a number of separate and less baffling questions.
"Divide and conquer" is the maxim of success here as elsewhere.
Let us illustrate these somewhat general maxims by examining their
application to the philosophy of space, for it is only in application
that the meaning or importance of a method can be understood. Suppose
we are confronted with the problem of space as presented in Kant's
Transcendental Aesthetic, and suppose we wish to discover what are the
elements of the problem and what hope there is of obtaining a solution
of them. It will soon appear that three entirely distinct problems,
belonging to different studies, and requiring different methods for
their solution, have been confusedly combined in the supposed single
problem with which Kant is concerned. There is a problem of logic, a
problem of physics, and a problem of theory of knowledge. Of these
three, the problem of logic can be solved exactly and perfectly; the
problem of physics can probably be solved with as great a degree of
certainty and as great an approach to exactness as can be hoped in an
empirical region; the problem of theory of knowledge, however, remains
very obscure and very difficult to deal with.
Let us see how these three problems arise.
Let us see how these three problems arise.
The logical problem has arisen through the suggestions of
non-Euclidean geometry. Given a body of geometrical propositions, it
is not difficult to find a minimum statement of the axioms from which
this body of propositions can be deduced. It is also not difficult, by
dropping or altering some of these axioms, to obtain a more general or
a different geometry, having, from the point of view of pure
mathematics, the same logical coherence and the same title to respect
as the more familiar Euclidean geometry. The Euclidean geometry itself
is true perhaps of actual space (though this is doubtful), but
certainly of an infinite number of purely arithmetical systems, each
of which, from the point of view of abstract logic, has an equal and
indefeasible right to be called a Euclidean space. Thus space as an
object of logical or mathematical study loses its uniqueness; not only
are there many kinds of spaces, but there are an infinity of examples
of each kind, though it is difficult to find any kind of which the
space of physics may be an example, and it is impossible to find any
kind of which the space of physics is certainly an example. As an
illustration of one possible logical system of geometry we may
consider all relations of three terms which are analogous in certain
formal respects to the relation "between" as it appears to be in
actual space. A space is then defined by means of one such three-term
relation. The points of the space are all the terms which have this
relation to something or other, and their order in the space in
question is determined by this relation. The points of one space are
necessarily also points of other spaces, since there are necessarily
other three-term relations having those same points for their field.
The space in fact is not determined by the class of its points, but by
the ordering three-term relation. When enough abstract logical
properties of such relations have been enumerated to determine the
resulting kind of geometry, say, for example, Euclidean geometry, it
becomes unnecessary for the pure geometer in his abstract capacity to
distinguish between the various relations which have all these
properties. He considers the whole class of such relations, not any
single one among them. Thus in studying a given kind of geometry the
pure mathematician is studying a certain class of relations defined by
means of certain abstract logical properties which take the place of
what used to be called axioms. The nature of geometrical reasoning
therefore is purely deductive and purely logical; if any special
epistemological peculiarities are to be found in geometry, it must not
be in the reasoning, but in our knowledge concerning the axioms in
some given space.
The physical problem of space is both more interesting and more
difficult than the logical problem.
The physical problem may be stated as follows: to find in the physical world, or to construct from physical materials, a space of one of the kinds enumerated by the logical treatment of geometry. This problem derives its difficulty from the attempt to accommodate to the roughness and vagueness of the real world some system possessing the logical clearness and exactitude of pure mathematics. That this can be done with a certain degree of approximation is fairly evident If I see three people A, B, and C sitting in a row, I become aware of the fact which may be expressed by saying that B is between A and C rather than that A is between B and C, or C is between A and B. This relation of "between" which is thus perceived to hold has some of the abstract logical properties of those three-term relations which, we saw, give rise to a geometry, but its properties fail to be exact, and are not, as empirically given, amenable to the kind of treatment at which geometry aims. In abstract geometry we deal with points, straight lines, and planes; but the three people A, B, and C whom I see sitting in a row are not exactly points, nor is the row exactly a straight line. Nevertheless physics, which formally assumes a space containing points, straight lines, and planes, is found empirically to give results applicable to the sensible world. It must therefore be possible to find an interpretation of the points, straight lines, and planes of physics in terms of physical data, or at any rate in terms of data together with such hypothetical additions as seem least open to question. Since all data suffer from a lack of mathematical precision through being of a certain size and somewhat vague in outline, it is plain that if such a notion as that of a point is to find any application to empirical material, the point must be neither a datum nor a hypothetical addition to data, but a construction by means of data with their hypothetical additions. It is obvious that any hypothetical filling out of data is less dubious and unsatisfactory when the additions are closely analogous to data than when they are of a radically different sort. To assume, for example, that objects which we see continue, after we have turned away our eyes, to be more or less analogous to what they were while we were looking, is a less violent assumption than to assume that such objects are composed of an infinite number of mathematical points. Hence in the physical study of the geometry of physical space, points must not be assumed ab initio as they are in the logical treatment of geometry, but must be constructed as systems composed of data and hypothetical analogues of data. We are thus led naturally to define a physical point as a certain class of those objects which are the ultimate constituents of the physical world. It will be the class of all those objects which, as one would naturally say, contain the point. To secure a definition giving this result, without previously assuming that physical objects are composed of points, is an agreeable problem in mathematical logic. The solution of this problem and the perception of its importance are due to my friend Dr. Whitehead. The oddity of regarding a point as a class of physical entities wears off with familiarity, and ought in any case not to be felt by those who maintain, as practically every one does, that points are mathematical fictions. The word "fiction" is used glibly in such connexions by many men who seem not to feel the necessity of explaining how it can come about that a fiction can be so useful in the study of the actual world as the points of mathematical physics have been found to be. By our definition, which regards a point as a class of physical objects, it is explained both how the use of points can lead to important physical results, and how we can nevertheless avoid the assumption that points are themselves entities in the physical world.
The physical problem may be stated as follows: to find in the physical world, or to construct from physical materials, a space of one of the kinds enumerated by the logical treatment of geometry. This problem derives its difficulty from the attempt to accommodate to the roughness and vagueness of the real world some system possessing the logical clearness and exactitude of pure mathematics. That this can be done with a certain degree of approximation is fairly evident If I see three people A, B, and C sitting in a row, I become aware of the fact which may be expressed by saying that B is between A and C rather than that A is between B and C, or C is between A and B. This relation of "between" which is thus perceived to hold has some of the abstract logical properties of those three-term relations which, we saw, give rise to a geometry, but its properties fail to be exact, and are not, as empirically given, amenable to the kind of treatment at which geometry aims. In abstract geometry we deal with points, straight lines, and planes; but the three people A, B, and C whom I see sitting in a row are not exactly points, nor is the row exactly a straight line. Nevertheless physics, which formally assumes a space containing points, straight lines, and planes, is found empirically to give results applicable to the sensible world. It must therefore be possible to find an interpretation of the points, straight lines, and planes of physics in terms of physical data, or at any rate in terms of data together with such hypothetical additions as seem least open to question. Since all data suffer from a lack of mathematical precision through being of a certain size and somewhat vague in outline, it is plain that if such a notion as that of a point is to find any application to empirical material, the point must be neither a datum nor a hypothetical addition to data, but a construction by means of data with their hypothetical additions. It is obvious that any hypothetical filling out of data is less dubious and unsatisfactory when the additions are closely analogous to data than when they are of a radically different sort. To assume, for example, that objects which we see continue, after we have turned away our eyes, to be more or less analogous to what they were while we were looking, is a less violent assumption than to assume that such objects are composed of an infinite number of mathematical points. Hence in the physical study of the geometry of physical space, points must not be assumed ab initio as they are in the logical treatment of geometry, but must be constructed as systems composed of data and hypothetical analogues of data. We are thus led naturally to define a physical point as a certain class of those objects which are the ultimate constituents of the physical world. It will be the class of all those objects which, as one would naturally say, contain the point. To secure a definition giving this result, without previously assuming that physical objects are composed of points, is an agreeable problem in mathematical logic. The solution of this problem and the perception of its importance are due to my friend Dr. Whitehead. The oddity of regarding a point as a class of physical entities wears off with familiarity, and ought in any case not to be felt by those who maintain, as practically every one does, that points are mathematical fictions. The word "fiction" is used glibly in such connexions by many men who seem not to feel the necessity of explaining how it can come about that a fiction can be so useful in the study of the actual world as the points of mathematical physics have been found to be. By our definition, which regards a point as a class of physical objects, it is explained both how the use of points can lead to important physical results, and how we can nevertheless avoid the assumption that points are themselves entities in the physical world.
Many of the mathematically convenient properties of abstract logical
spaces cannot be either known to belong or known not to belong to the
space of physics. Such are all the properties connected with
continuity. For to know that actual space has these properties would
require an infinite exactness of sense-perception. If actual space is
continuous, there are nevertheless many possible non-continuous spaces
which will be empirically indistinguishable from it; and, conversely,
actual space may be non-continuous and yet empirically
indistinguishable from a possible continuous space. Continuity,
therefore, though obtainable in the a priori region of arithmetic,
is not with certainty obtainable in the space or time of the physical
world: whether these are continuous or not would seem to be a question
not only unanswered but for ever unanswerable. From the point of view
of philosophy, however, the discovery that a question is unanswerable
is as complete an answer as any that could possibly be obtained. And
from the point of view of physics, where no empirical means of
distinction can be found, there can be no empirical objection to the
mathematically simplest assumption, which is that of continuity.
The subject of the physical theory of space is a very large one,
hitherto little explored. It is associated with a similar theory of
time, and both have been forced upon the attention of philosophically
minded physicists by the discussions which have raged concerning the
theory of relativity.
The problem with which Kant is concerned in the Transcendental Aesthetic is primarily the epistemological problem: "How do we come to
have knowledge of geometry a priori ?" By the distinction between the
logical and physical problems of geometry, the bearing and scope of
this question are greatly altered. Our knowledge of pure geometry is
a priori but is wholly logical. Our knowledge of physical geometry
is synthetic, but is not a priori. Our knowledge of pure geometry is
hypothetical, and does not enable us to assert, for example, that the
axiom of parallels is true in the physical world. Our knowledge of
physical geometry, while it does enable us to assert that this axiom
is approximately verified, does not, owing to the inevitable
inexactitude of observation, enable us to assert that it is verified
exactly. Thus, with the separation which we have made between pure
geometry and the geometry of physics, the Kantian problem collapses.
To the question, "How is synthetic a priori knowledge possible ?" we
can now reply, at any rate so far as geometry is concerned, "It is not
possible," if "synthetic" means "not deducible from logic alone." Our
knowledge of geometry, like the rest of our knowledge, is derived
partly from logic, partly from sense, and the peculiar position which
in Kant's day geometry appeared to occupy is seen now to be a
delusion. There are still some philosophers, it is true, who maintain
that our knowledge that the axiom of parallels, for example, is true
of actual space, is not to be accounted for empirically, but is as
Kant maintained derived from an a priori intuition. This position is
not logically refutable, but I think it loses all plausibility as soon
as we realise how complicated and derivative is the notion of physical
space. As we have seen, the application of geometry to the physical
world in no way demands that there should really be points and
straight lines among physical entities.
The principle of economy, therefore, demands that we should abstain from assuming the existence of points and straight lines. As soon, however, as we accept the view that points and straight lines are complicated constructions by means of classes of physical entities, the hypothesis that we have an a priori intuition enabling us to know what happens to straight lines when they are produced indefinitely becomes extremely strained and harsh; nor do I think that such an hypothesis would ever have arisen in the mind of a philosopher who had grasped the nature of physical space. Kant, under the influence of Newton, adopted, though with some vacillation, the hypothesis of absolute space, and this hypothesis, though logically unobjectionable, is removed by Occam's razor, since absolute space is an unnecessary entity in the explanation of the physical world. Although, therefore, we cannot refute the Kantian theory of an a priori intuition, we can remove its grounds one by one through an analysis of the problem. Thus, here as in many other philosophical questions, the analytic method, while not capable of arriving at a demonstrative result, is nevertheless capable of showing that all the positive grounds in favour of a certain theory are fallacious and that a less unnatural theory is capable of accounting for the facts.
The principle of economy, therefore, demands that we should abstain from assuming the existence of points and straight lines. As soon, however, as we accept the view that points and straight lines are complicated constructions by means of classes of physical entities, the hypothesis that we have an a priori intuition enabling us to know what happens to straight lines when they are produced indefinitely becomes extremely strained and harsh; nor do I think that such an hypothesis would ever have arisen in the mind of a philosopher who had grasped the nature of physical space. Kant, under the influence of Newton, adopted, though with some vacillation, the hypothesis of absolute space, and this hypothesis, though logically unobjectionable, is removed by Occam's razor, since absolute space is an unnecessary entity in the explanation of the physical world. Although, therefore, we cannot refute the Kantian theory of an a priori intuition, we can remove its grounds one by one through an analysis of the problem. Thus, here as in many other philosophical questions, the analytic method, while not capable of arriving at a demonstrative result, is nevertheless capable of showing that all the positive grounds in favour of a certain theory are fallacious and that a less unnatural theory is capable of accounting for the facts.
Another question by which the capacity of the analytic method can be
shown is the question of realism. Both those who advocate and those
who combat realism seem to me to be far from clear as to the nature of
the problem which they are discussing. If we ask: "Are our objects of
perception real and are they independent of the percipient?" it
must be supposed that we attach some meaning to the words "real" and
"independent," and yet, if either side in the controversy of realism
is asked to define these two words, their answer is pretty sure to
embody confusions such as logical analysis will reveal.
Let us begin with the word "real." There certainly are objects of
perception, and therefore, if the question whether these objects are
real is to be a substantial question, there must be in the world two
sorts of objects, namely, the real and the unreal, and yet the unreal
is supposed to be essentially what there is not. The question what
properties must belong to an object in order to make it real is one to
which an adequate answer is seldom if ever forthcoming. There is of
course the Hegelian answer, that the real is the self-consistent and
that nothing is self-consistent except the Whole; but this answer,
true or false, is not relevant in our present discussion, which moves
on a lower plane and is concerned with the status of objects of
perception among other objects of equal fragmentariness. Objects of
perception are contrasted, in the discussions concerning realism,
rather with psychical states on the one hand and matter on the other
hand than with the all-inclusive whole of things. The question we have
therefore to consider is the question as to what can be meant by
assigning "reality" to some but not all of the entities that make up
the world. Two elements, I think, make up what is felt rather than
thought when the word "reality" is used in this sense. A thing is real
if it persists at times when it is not perceived; or again, a thing is
real when it is correlated with other things in a way which experience
has led us to expect. It will be seen that reality in either of these
senses is by no means necessary to a thing, and that in fact there
might be a whole world in which nothing was real in either of these
senses. It might turn out that the objects of perception failed of
reality in one or both of these respects, without its being in any way
deducible that they are not parts of the external world with which
physics deals. Similar remarks will apply to the word "independent."
Most of the associations of this word are bound up with ideas as to
causation which it is not now possible to maintain. A is independent
of B when B is not an indispensable part of the cause of A.
But when it is recognised that causation is nothing more than
correlation, and that there are correlations of simultaneity as well
as of succession, it becomes evident that there is no uniqueness in a
series of casual antecedents of a given event, but that, at any point
where there is a correlation of simultaneity, we can pass from one
line of antecedents to another in order to obtain a new series of
causal antecedents. It will be necessary to specify the causal law
according to which the antecedents are to be considered. I received a
letter the other day from a correspondent who had been puzzled by
various philosophical questions. After enumerating them he says:
"These questions led me from Bonn to Strassburg, where I found
Professor Simmel." Now, it would be absurd to deny that these
questions caused his body to move from Bonn to Strassburg, and yet it
must be supposed that a set of purely mechanical antecedents could
also be found which would account for this transfer of matter from one
place to another. Owing to this plurality of causal series antecedent
to a given event, the notion of the cause becomes indefinite, and
the question of independence becomes correspondingly ambiguous. Thus,
instead of asking simply whether A is independent of B, we ought
to ask whether there is a series determined by such and such causal
laws leading from B to A. This point is important in connexion
with the particular question of objects of perception. It may be that
no objects quite like those which we perceive ever exist unperceived; in this case there will be a causal law according to which objects of
perception are not independent of being perceived. But even if this be
the case, it may nevertheless also happen that there are purely
physical causal laws determining the occurrence of objects which are
perceived by means of other objects which perhaps are not perceived.
In that case, in regard to such causal laws objects of perception will
be independent of being perceived. Thus the question whether objects
of perception are independent of being perceived is, as it stands,
indeterminate, and the answer will be yes or no according to the
method adopted of making it determinate. I believe that this confusion
has borne a very large part in prolonging the controversies on this
subject, which might well have seemed capable of remaining for ever
undecided. The view which I should wish to advocate is that objects of
perception do not persist unchanged at times when they are not
perceived, although probably objects more or less resembling them do
exist at such times; that objects of perception are part, and the only
empirically knowable part, of the actual subject-matter of physics,
and are themselves properly to be called physical; that purely
physical laws exist determining the character and duration of objects
of perception without any reference to the fact that they are
perceived; and that in the establishment of such laws the propositions
of physics do not presuppose any propositions of psychology or even
the existence of mind. I do not know whether realists would recognise
such a view as realism. All that I should claim for it is, that it
avoids difficulties which seem to me to beset both realism and
idealism as hitherto advocated, and that it avoids the appeal which
they have made to ideas which logical analysis shows to be ambiguous.
A further defence and elaboration of the positions which I advocate,
but for which time is lacking now, will be found indicated in my book
on Our Knowledge of the External World.
The adoption of scientific method in philosophy, if I am not mistaken,
compels us to abandon the hope of solving many of the more ambitious
and humanly interesting problems of traditional philosophy. Some of
these it relegates, though with little expectation of a successful
solution, to special sciences, others it shows to be such as our
capacities are essentially incapable of solving. But there remain a
large number of the recognised problems of philosophy in regard to
which the method advocated gives all those advantages of division into
distinct questions, of tentative, partial, and progressive advance,
and of appeal to principles with which, independently of temperament,
all competent students must agree. The failure of philosophy hitherto
has been due in the main to haste and ambition: patience and modesty,
here as in other sciences, will open the road to solid and durable
progress.
