'He who begins by loving Christianity better than Truth, will proceed
by loving his own sect or Church better than Christianity, and end
in loving himself better than all.'
Inquiry into the evidence of a doctrine is not to be made once for
all, and then taken as finally settled. It is never lawful to stifle a
doubt; for either it can be honestly answered by means of the inquiry
already made, or else it proves that the inquiry was not complete.
'But,' says one, 'I am a busy man; I have no time for the long course
of study which would be necessary to make me in any degree a competent
judge of certain questions, or even able to understand the nature of
the arguments.' Then he should have no time to believe.
II. The Weight of Authority.--Are we then to become universal skeptics,
doubting everything, afraid always to put one foot before the other
until we have personally tested the firmness of the road? Are we
to deprive ourselves of the help and guidance of that vast body of
knowledge which is daily growing upon the world, because neither
we nor any other one person can possibly test a hundredth part of
it by immediate experiment or observation, and because it would not
be completely proved if we did? Shall we steal and tell lies because
we have had no personal experience wide enough to justify the belief
that it is wrong to do so?
There is no practical danger that such consequences will ever follow
from scrupulous care and self-control in the matter of belief. Those
men who have most nearly done their duty in this respect have found
that certain great principles, and these most fitted for the guidance
of life, have stood out more and more clearly in proportion to the
care and honesty with which they were tested, and have acquired in
this way a practical certainty. The beliefs about right and wrong
which guide our actions in dealing with men in society, and the beliefs
about physical nature which guide our actions in dealing with animate
and inanimate bodies, these never suffer from investigation; they
can take care of themselves, without being propped up by 'acts of
faith,' the clamor of paid advocates, or the suppression of contrary
evidence. Moreover there are many cases in which it is our duty
to act upon probabilities, although the evidence is not such as to
justify present belief; because it is precisely by such action, and
by observation of its fruits, that evidence is got which may justify
future belief. So that we have no reason to fear lest a habit of
conscientious inquiry should paralyze the actions of our daily life.
But because it is not enough to say, 'It is wrong to believe on
unworthy evidence,' without saying also what evidence is worthy,
we shall now go on to inquire under what circumstances it is lawful
to believe on the testimony of others; and then, further, we shall
inquire more generally when and why we may believe that which goes
beyond our own experience, or even beyond the experience of mankind.
In what cases, then, let us ask in the first place, is the testimony
of a man unworthy of belief? He may say that which is untrue either
knowingly or unknowingly. In the first case he is lying, and his moral
character is to blame; in the second case he is ignorant or mistaken,
and it is only his knowledge or his judgment which is in fault. In
order that we may have the right to accept his testimony as ground for
believing what he says, we must have reasonable grounds for trusting
his veracity, that he is really trying to speak the truth so far as he
knows it; his knowledge, that he has had opportunities of knowing the
truth about this matter; and his judgment, that he has made proper use
of those opportunities in coming to the conclusion which he affirms.
However plain and obvious these reasons may be, so that no man of
ordinary intelligence, reflecting upon the matter, could fail to
arrive at them, it is nevertheless true that a great many persons
do habitually disregard them in weighing testimony. Of the two
questions, equally important to the trustworthiness of a witness,
'Is he dishonest?' and 'May he be mistaken?' the majority of mankind
are perfectly satisfied if one can, with some show of probability,
be answered in the negative. The excellent moral character of a man
is alleged as ground for accepting his statements about things which
he cannot possibly have known. A Mohammedan, for example, will tell
us that the character of his Prophet was so noble and majestic that
it commands the reverence even of those who do not believe in his
mission. So admirable was his moral teaching, so wisely put together
the great social machine which he created, that his precepts have not
only been accepted by a great portion of mankind, but have actually
been obeyed. His institutions have on the one hand rescued the negro
from savagery, and on the other hand have taught civilization to the
advancing West; and although the races which held the highest forms
of his faith, and most fully embodied his mind and thought, have all
been conquered and swept away by barbaric tribes, yet the history
of their marvellous attainments remains as an imperishable glory to
Islam. Are we to doubt the word of a man so great and so good? Can we
suppose that this magnificent genius, this splendid moral hero, has
lied to us about the most solemn and sacred matters? The testimony of
Mohammed is clear, that there is but one God, and that he, Mohammed,
is his prophet; that if we believe in him we shall enjoy everlasting
felicity, but that if we do not we shall be damned. This testimony
rests on the most awful of foundations, the revelation of heaven
itself; for was he not visited by the angel Gabriel, as he fasted and
prayed in his desert cave, and allowed to enter into the blessed fields
of Paradise? Surely God is God and Mohammed is the Prophet of God.
What should we answer to this Mussulman? First, no doubt, we should
be tempted to take exception against his view of the character
of the Prophet and the uniformly beneficial influence of Islam:
before we could go with him altogether in these matters it might seem
that we should have to forget many terrible things of which we have
heard or read. But if we chose to grant him all these assumptions,
for the sake of argument, and because it is difficult both for the
faithful and for infidels to discuss them fairly and without passion,
still we should have something to say which takes away the ground
of his belief, and therefore shows that it is wrong to entertain
it. Namely this: the character of Mohammed is excellent evidence
that he was honest and spoke the truth so far as he knew it; but it
is no evidence at all that he knew what the truth was. What means
could he have of knowing that the form which appeared to him to be
the angel Gabriel was not a hallucination, and that his apparent
visit to Paradise was not a dream? Grant that he himself was fully
persuaded and honestly believed that he had the guidance of heaven,
and was the vehicle of a supernatural revelation, how could he know
that this strong conviction was not a mistake? Let us put ourselves
in his place; we shall find that the more completely we endeavor
to realize what passed through his mind, the more clearly we shall
perceive that the Prophet could have had no adequate ground for the
belief in his own inspiration. It is most probable that he himself
never doubted of the matter, or thought of asking the question; but
we are in the position of those to whom the question has been asked,
and who are bound to answer it. It is known to medical observers that
solitude and want of food are powerful means of producing delusion
and of fostering a tendency to mental disease. Let us suppose, then,
that I, like Mohammed, go into desert places to fast and pray; what
things can happen to me which will give me the right to believe that I
am divinely inspired? Suppose that I get information, apparently from
a celestial visitor, which upon being tested is found to be correct. I
cannot be sure, in the first place, that the celestial visitor is not
a figment of my own mind, and that the information did not come to me,
unknown at the time to my consciousness, through some subtle channel of
sense. But if my visitor were a real visitor, and for a long time gave
me information which was found to be trustworthy, this would indeed
be good ground for trusting him in the future as to such matters as
fall within human powers of verification; but it would not be ground
for trusting his testimony as to any other matters. For although his
tested character would justify me in believing that he spoke the truth
so far as he knew, yet the same question would present itself--what
ground is there for supposing that he knows?
Even if my supposed visitor had given me such information, subsequently
verified by me, as proved him to have means of knowledge about
verifiable matters far exceeding my own; this would not justify me in
believing what he said about matters that are not at present capable
of verification by man. It would be ground for interesting conjecture,
and for the hope that, as the fruit of our patient inquiry, we might
by and by attain to such a means of verification as should rightly
turn conjecture into belief. For belief belongs to man, and to the
guidance of human affairs: no belief is real unless it guide our
actions, and those very actions supply a test of its truth.
But, it may be replied, the acceptance of Islam as a system is
just that action which is prompted by belief in the mission of the
Prophet, and which will serve for a test of its truth. Is it possible
to believe that a system which has succeeded so well is really founded
upon a delusion? Not only have individual saints found joy and peace in
believing, and verified those spiritual experiences which are promised
to the faithful, but nations also have been raised from savagery or
barbarism to a higher social state. Surely we are at liberty to say
that the belief has been acted upon, and that it has been verified.
It requires, however, but little consideration to show that what
has really been verified is not at all the supernal character of the
Prophet's mission, or the trustworthiness of his authority in matters
which we ourselves cannot test, but only his practical wisdom in
certain very mundane things. The fact that believers have found joy
and peace in believing gives us the right to say that the doctrine
is a comfortable doctrine, and pleasant to the soul; but it does not
give us the right to say that it is true. And the question which our
conscience is always asking about that which we are tempted to believe
is not, 'Is it comfortable and pleasant?' but, 'Is it true?' That
the Prophet preached certain doctrines, and predicted that spiritual
comfort would be found in them, proves only his sympathy with human
nature and his knowledge of it; but it does not prove his superhuman
knowledge of theology.
And if we admit for the sake of argument (for it seems that we cannot
do more) that the progress made by Moslem nations in certain cases
was really due to the system formed and sent forth into the the world
by Mohammed, we are not at liberty to conclude from this that he was
inspired to declare the truth about things which we cannot verify. We
are only at liberty to infer the excellence of his moral precepts,
or of the means which he devised for so working upon men as to get
them obeyed, or of the social and political machinery which he set
up. And it would require a great amount of careful examination into
the history of those nations to determine which of these things
had the greater share in the result. So that here again it is the
Prophet's knowledge of human nature, and his sympathy with it, that
are verified; not his divine inspiration, or his knowledge of theology.
If there were only one Prophet, indeed, it might well seem a difficult
and even an ungracious task to decide upon what points we would
trust him, and on what we would doubt his authority; seeing what help
and furtherance all men have gained in all ages from those who saw
more clearly, who felt more strongly, and who sought the truth with
more single heart than their weaker brethren. But there is not only
one Prophet; and while the consent of many upon that which, as men,
they had real means of knowing and did know, has endured to the end,
and been honorably built into the great fabric of human knowledge,
the diverse witness of some about that which they did not and could
not know remains as a warning to us that to exaggerate the prophetic
authority is to misuse it, and to dishonor those who have sought
only to help and further us after their power. It is hardly in human
nature that a man should quite accurately gauge the limits of his own
insight; but it is the duty of those who profit by his work to consider
carefully where he may have been carried beyond it. If we must needs
embalm his possible errors along with his solid achievements, and use
his authority as an excuse for believing what he cannot have known,
we make of his goodness an occasion to sin.
To consider only one other such witness: the followers of the Buddha
have at least as much right to appeal to individual and social
experience in support of the authority of the Eastern saviour. The
special mark of his religion, it is said, that in which it has never
been surpassed, is the comfort and consolation which it gives to
the sick and sorrowful, the tender sympathy with which it soothes and
assuages all the natural griefs of men. And surely no triumph of social
morality can be greater or nobler than that which has kept nearly half
the human race from persecuting in the name of religion. If we are to
trust the accounts of his early followers, he believed himself to have
come upon earth with a divine and cosmic mission to set rolling the
wheel of the law. Being a prince, he divested himself of his kingdom,
and of his free will became acquainted with misery, that he might
learn how to meet and subdue it. Could such a man speak falsely about
solemn things? And as for his knowledge, was he not a man miraculous
with powers more than man's? He was born of woman without the help
of man; he rose into the air and was transfigured before his kinsmen;
at last he went up bodily into heaven from the top of Adam's Peak. Is
not his word to be believed in when he testifies of heavenly things?
If there were only he, and no other, with such claims! But there
is Mohammed with his testimony; we cannot choose but listen to them
both. The Prophet tells us that there is one God, and that we shall
live forever in joy or misery, according as we believe in the Prophet
or not. The Buddha says that there is no God, and that we shall be
annihilated by and by if we are good enough. Both cannot be infallibly
inspired; one or the other must have been the victim of a delusion,
and thought he knew that which he really did not know. Who shall dare
to say which? and how can we justify ourselves in believing that the
other was not also deluded?
We are led, then, to these judgments following. The goodness and
greatness of a man do not justify us in accepting a belief upon the
warrant of his authority, unless there are reasonable grounds for
supposing that he knew the truth of what he was saying. And there
can be no grounds for supposing that a man knows that which we,
without ceasing to be men, could not be supposed to verify.
If a chemist tells me, who am no chemist, that a certain substance can
be made by putting together other substances in certain proportions and
subjecting them to a known process, I am quite justified in believing
this upon his authority, unless I know anything against his character
or his judgment. For his professional training is one which tends to
encourage veracity and the honest pursuit of truth, and to produce a
dislike of hasty conclusions and slovenly investigation. And I have
reasonable ground for supposing that he knows the truth of what he
is saying, for although I am no chemist, I can be made to understand
so much of the methods and processes of the science as makes it
conceivable to me that, without ceasing to be man, I might verify the
statement. I may never actually verify it, or even see any experiment
which goes toward verifying it; but still I have quite reason enough
to justify me in believing that the verification is within the reach
of human appliances and powers, and in particular that it has been
actually performed by my informant. His result, the belief to which he
has been led by his inquiries, is valid not only for himself but for
others; it is watched and tested by those who are working in the same
ground and who know that no greater service can be rendered to science
than the purification of accepted results from the errors which may
have crept into them. It is in this way that the result becomes common
property, a right object of belief, which is a social affair and matter
of public business. Thus it is to be observed that his authority is
valid because there are those who question it and verify it; that it
is precisely this process of examining and purifying that keeps alive
among investigators the love of that which shall stand all possible
tests, the sense of public responsibility as of those whose work,
if well done, shall remain as the enduring heritage of mankind.
But if my chemist tells me that an atom of oxygen has existed unaltered
in weight and rate of vibration throughout all time, I have no right
to believe this on his authority, for it is a thing which he cannot
know without ceasing to be man. He may quite honestly believe that
this statement is a fair inference from his experiments, but in that
case his judgment is at fault. A very simple consideration of the
character of experiments would show him that they never can lead to
results of such a kind; that being themselves only approximate and
limited, they cannot give us knowledge which is exact and universal. No
eminence of character and genius can give a man authority enough to
justify us in believing him when he makes statements implying exact
or universal knowledge.
Again, an Arctic explorer may tell us that in a given latitude and
longitude he has experienced such and such a degree of cold, that the
sea was of such a depth, and the ice of such a character. We should
be quite right to believe him, in the absence of any stain upon his
veracity. It is conceivable that we might, without ceasing to be men,
go there and verify his statement; it can be tested by the witness of
his companions, and there is adequate ground for supposing that he
knows the truth of what he is saying. But if an old whaler tells us
that the ice is three hundred feet thick all the way up to the Pole,
we shall not be justified in believing him. For although the statement
may be capable of verification by man, it is certainly not capable
of verification by him, with any means and appliances which he has
possessed; and he must have persuaded himself of the truth of it by
some means which does not attach any credit to his testimony. Even if,
therefore, the matter affirmed is within the reach of human knowledge,
we have no right to accept it upon authority unless it is within the
reach of our informant's knowledge.
What shall we say of that authority, more venerable and august than any
individual witness, the time-honored tradition of the human race? An
atmosphere of beliefs and conceptions has been formed by the labors
and struggles of our forefathers, which enables us to breathe amid the
various and complex circumstances of our life. It is around and about
us and within us; we cannot think except in the forms and processes
of thought which it supplies. Is it possible to doubt and to test
it? and if possible, is it right?
We shall find reason to answer that it is not only possible and
right, but our bounden duty; that the main purpose of the tradition
itself is to supply us with the means of asking questions, of testing
and inquiring into things; that if we misuse it, and take it as a
collection of cut-and-dried statements, to be accepted without further
inquiry, we are not only injuring ourselves here, but by refusing
to do our part toward the building up of the fabric which shall be
inherited by our children, we are tending to cut off ourselves and
our race from the human line.
Let us first take care to distinguish a kind of tradition which
especially requires to be examined and called in question, because
it especially shrinks from inquiry. Suppose that a medicine-man in
Central Africa tells his tribe that a certain powerful medicine in his
tent will be propitiated if they kill their cattle; and that the tribe
believe him. Whether the medicine was propitiated or not, there are
no means of verifying, but the cattle are gone. Still the belief may
be kept up in the tribe that propitiation has been effected in this
way; and in a later generation it will be all the easier for another
medicine-man to persuade them to a similar act. Here the only reason
for belief is that everybody has believed the thing for so long that
it must be true. And yet the belief was founded on fraud, and has
been propagated by credulity. That man will undoubtedly do right,
and be a friend of men who shall call it in question and see that
there is no evidence for it, help his neighbors to see as he does,
and even, if need be, go into the holy tent and break the medicine.
The rule, which should guide us in such cases is simple and obvious
enough: that the aggregate testimony of our neighbors is subject
to the same conditions as the testimony of any one of them. Namely,
we have no right to believe a thing true because everybody says so,
unless there are good grounds for believing that some one person
at least has the means of knowing what is true, and is speaking the
truth so far as he knows it. However many nations and generations of
men are brought into the witness-box, they cannot testify to anything
which they do not know. Every man who has accepted the statement from
somebody else, without himself testing and verifying it, is out of
court; his word is worth nothing at all. And when we get back at last
to the true birth and beginning of the statement, two serious questions
must be disposed of in regard to him who first made it: was he mistaken
in thinking that he knew about this matter, or was he lying?
This last question is unfortunately a very actual and practical one
even to us at this day and in this country. We have no occasion to
go to La Salette, or to Central Africa, or to Lourdes, for examples
of immoral and debasing superstition. It is only too possible for
a child to grow up in London surrounded by an atmosphere of beliefs
fit only for the savage, which have in our own time been founded in
fraud and propagated by credulity.
Laying aside, then, such tradition as is handed on without testing
by successive generations, let us consider that which is truly built
up out of the common experience of mankind. This great fabric is for
the guidance of our thoughts, and through them of our actions, both in
the moral and in the material world. In the moral world, for example,
it gives us the conceptions of right in general, of justice, of truth,
of beneficence, and the like. These are given as conceptions, not as
statements or propositions; they answer to certain definite instincts,
which are certainly within us, however they came there. That it is
right to be beneficent is matter of immediate personal experience;
for when a man retires within himself and there finds something,
wider and more lasting than his solitary personality which says,
'I want to do right,' as well as, 'I want to do good to man,' he can
verify by direct observation that one instinct is founded upon and
agrees fully with the other. And it is his duty so to verify this
and all similar statements.
The tradition says also, at a definite place and time, that such and
such actions are just, or true, or beneficent. For all such rules a
further inquiry is necessary, since they are sometimes established
by an authority other than that of the moral sense founded on
experience. Until recently, the moral tradition of our own country--and
indeed of all Europe--taught that it was beneficent to give money
indiscriminately to beggars. But the questioning of this rule, and
investigation into it, led men to see that true beneficence is that
which helps a man to do the work which he is most fitted for, not that
which keeps and encourages him in idleness; and that to neglect this
distinction in the present is to prepare pauperism and misery for
the future. By this testing and discussion, not only has practice
been purified and made more beneficent, but the very conception
of beneficence has been made wider and wiser. Now here the great
social heirloom consists of two parts: the instinct of beneficence,
which makes a certain side of our nature, when predominant, wish
to do good to men; and the intellectual conception of beneficence,
which we can compare with any proposed course of conduct and ask,
'Is this beneficent or not?' By the continual asking and answering
of such questions the conception grows in breadth and distinctness,
and the instinct becomes strengthened and purified. It appears then
that the great use of the conception, the intellectual part of the
heirloom, is to enable us to ask questions; that it grows and is kept
straight by means of these questions; and if we do not use it for that
purpose we shall gradually lose it altogether, and be left with a mere
code of regulations which cannot rightly be called morality at all.
Such considerations apply even more obviously and clearly, if possible,
to the store of beliefs and conceptions which our fathers have amassed
for us in respect of the material world. We are ready to laugh at the
rule of thumb of the Australian, who continues to tie his hatchet to
the side of the handle, although the Birmingham fitter has made a
hole on purpose for him to put the handle in. His people have tied
up hatchets so for ages: who is he that he should set himself up
against their wisdom? He has sunk so low that he cannot do what some
of them must have done in the far distant past--call in question an
established usage, and invent or learn something better. Yet here,
in the dim beginning of knowledge, where science and art are one,
we find only the same simple rule which applies to the highest and
deepest growths of that cosmic Tree; to its loftiest flower-tipped
branches as well as to the profoundest of its hidden roots; the rule,
namely, that what is stored up and handed down to us is rightly used
by those who act as the makers acted, when they stored it up; those
who use it to ask further questions, to examine, to investigate;
who try honestly and solemnly to find out what is the right way of
looking at things and of dealing with them.
A question rightly asked is already half answered, said Jacobi; we may
add that the method of solution is the other half of the answer, and
that the actual result counts for nothing by the side of these two. For
an example let us go to the telegraph, where theory and practice,
grown each to years of discretion, are marvelously wedded for the
fruitful service of men. Ohm found that the strength of an electric
current is directly proportional to the strength of the battery which
produces it, and inversely as the length of the wire along which it
has to travel. This is called Ohm's law; but the result, regarded
as a statement to be believed, is not the valuable part of it. The
first half is the question: what relation holds good between these
quantities? So put, the question involves already the conception of
strength of current, and of strength of battery, as quantities to be
measured and compared; it hints clearly that these are the things to
be attended to in the study of electric currents. The second half
is the method of investigation; how to measure these quantities,
what instruments are required for the experiment, and how are they
to be used? The student who begins to learn about electricity is not
asked to believe in Ohm's law: he is made to understand the question,
he is placed before the apparatus, and he is taught to verify it. He
learns to do things, not to think he knows things; to use instruments
and to ask questions, not to accept a traditional statement. The
question which required a genius to ask it rightly is answered by a
tyro. If Ohm's law were suddenly lost and forgotten by all men, while
the question and the method of solution remained, the result could
be rediscovered in an hour. But the result by itself, if known to a
people who could not comprehend the value of the question or the means
of solving it, would be like a watch in the hands of a savage who could
not wind it up, or an iron steam-ship worked by Spanish engineers.
In regard, then, to the sacred tradition of humanity, we learn
that it consists, not in propositions or statements which are to
be accepted and believed on the authority of the tradition, but
in questions rightly asked, in conceptions which enable us to ask
further questions, and in methods of answering questions. The value
of all these things depends on their being tested day by day. The
very sacredness of the precious deposit imposes upon us the duty and
the responsibility of testing it, of purifying and enlarging it to
the utmost of our power. He who makes use of its results to stifle
his own doubts, or to hamper the inquiry of others, is guilty of a
sacrilege which centuries shall never be able to blot out. When the
labors and questionings of honest and brave men shall have built up
the fabric of known truth to a glory which we in this generation can
neither hope for nor imagine, in that pure and holy temple he shall
have no part nor lot, but his name and his works shall be cast out
into the darkness of oblivion forever.
III. The Limits of Inference.--The question in what cases we may
believe that which goes beyond our experience, is a very large and
delicate one, extending to the whole range of scientific method, and
requiring a considerable increase in the application of it before it
can be answered with anything approaching to completeness. But one
rule, lying on the threshold of the subject, of extreme simplicity
and vast practical importance, may here be touched upon and shortly
laid down.
A little reflection will show us that every belief, even the simplest
and most fundamental, goes beyond experience when regarded as a guide
to our actions. A burnt child dreads the fire, because it believes
that the fire will burn it to-day just as it did yesterday; but this
belief goes beyond experience, and assumes that the unknown fire
of to-day is like the known fire of yesterday. Even the belief that
the child was burnt yesterday goes beyond present experience, which
contains only the memory of a burning, and not the burning itself;
it assumes, therefore, that this memory is trustworthy, although we
know that a memory may often be mistaken. But if it is to be used as a
guide to action, as a hint of what the future is to be, it must assume
something about that future, namely, that it will be consistent with
the supposition that the burning really took place yesterday; which
is going beyond experience. Even the fundamental 'I am,' which cannot
be doubted, is no guide to action until it takes to itself 'I shall
be,' which goes beyond experience. The question is not, therefore,
'May we believe what goes beyond experience?' for this is involved
in the very nature of belief; but 'How far and in what manner may we
add to our experience in forming our beliefs?'
And an answer, of utter simplicity and universality, is suggested by
the example we have taken: a burnt child dreads the fire. We may go
beyond experience by assuming that what we do not know is like what
we do know; or, in other words, we may add to our experience on the
assumption of a uniformity in nature. What this uniformity precisely
is, how we grow in the knowledge of it from generation to generation,
these are questions which for the present we lay aside, being content
to examine two instances which may serve to make plainer the nature
of the rule.
From certain observations made with the spectroscope, we infer the
existence of hydrogen in the sun. By looking into the spectroscope when
the sun is shining on its slit, we see certain definite bright lines:
and experiments made upon bodies on the earth have taught us that when
these bright lines are seen hydrogen is the source of them. We assume,
then, that the unknown bright lines in the sun are like the known
bright lines of the laboratory, and that hydrogen in the sun behaves
as hydrogen under similar circumstances would behave on the earth.
But are we not trusting our spectroscope too much? Surely, having found
it to be trustworthy for terrestrial substances, where its statements
can be verified by man, we are justified in accepting its testimony
in other like cases; but not when it gives us information about things
in the sun, where its testimony cannot be directly verified by man?
Certainly, we want to know a little more before this inference can
be justified; and fortunately we do know this. The spectroscope
testifies to exactly the same thing in the two cases; namely, that
light-vibrations of a certain rate are being sent through it. Its
construction is such that if it were wrong about this in one case,
it would be wrong in the other. When we come to look into the matter,
we find that we have really assumed the matter of the sun to be like
the matter of the earth, made up of a certain number of distinct
substances; and that each of these, when very hot, has a distinct rate
of vibration, by which it may be recognized and singled out from the
rest. But this is the kind of assumption which we are justified in
using when we add to our experience. It is an assumption of uniformity
in nature, and can only be checked by comparison with many similar
assumptions which we have to make in other such cases.
But is this a true belief, of the existence of hydrogen in the sun? Can
it help in the right guidance of human action?
Certainly not, if it is accepted on unworthy grounds, and without
some understanding of the process by which it is got at. But when
this process is taken in as the ground of the belief, it becomes a
very serious and practical matter. For if there is no hydrogen in
the sun, the spectroscope--that is to say, the measurement of rates
of vibration--must be an uncertain guide in recognizing different
substances; and consequently it ought not to be used in chemical
analysis--in assaying, for example--to the great saving of time,
trouble, and money. Whereas the acceptance of the spectroscopic
method as trustworthy, has enriched us not only with new metals,
which is a great thing, but with new processes of investigation,
which is vastly greater.
For another example, let us consider the way in which we infer
the truth of an historical event--say the siege of Syracuse in the
Peloponnesian war. Our experience is that manuscripts exist which
are said to be and which call themselves manuscripts of the history
of Thucydides; that in other manuscripts, stated to be by later
historians, he is described as living during the time of the war; and
that books, supposed to date from the revival of learning, tell us how
these manuscripts had been preserved and were then acquired. We find
also that men do not, as a rule, forge books and histories without a
special motive; we assume that in this respect men in the past were
like men in the present; and we observe that in this case no special
motive was present. That is, we add to our experience on the assumption
of a uniformity in the characters of men. Because our knowledge of
this uniformity is far less complete and exact than our knowledge of
that which obtains in physics, inferences of the historical kind are
more precarious and less exact than inferences in many other sciences.
But if there is any special reason to suspect the character of the
persons who wrote or transmitted certain books, the case becomes
altered. If a group of documents give internal evidence that they
were produced among people who forged books in the names of others,
and who, in describing events, suppressed those things which did not
suit them, while they amplified such as did suit them; who not only
committed these crimes, but gloried in them as proofs of humility and
zeal; then we must say that upon such documents no true historical
inference can be founded, but only unsatisfactory conjecture.
We may, then, add to our experience on the assumption of a uniformity
in nature; we may fill in our picture of what is and has been, as
experience gives it us, in such a way as to make the whole consistent
with this uniformity. And practically demonstrative inference--that
which gives us a right to believe in the result of it--is a clear
showing that in no other way than by the truth of this result can
the uniformity of nature be saved.
No evidence, therefore, can justify us in believing the truth of
a statement which is contrary to, or outside of, the uniformity
of nature. If our experience is such that it cannot be filled up
consistently with uniformity, all we have a right to conclude is that
there is something wrong somewhere; but the possibility of inference
is taken away; we must rest in our experience, and not go beyond it at
all. If an event really happened which was not a part of the uniformity
of nature, it would have two properties: no evidence could give the
right to believe it to any except those whose actual experience it was;
and no inference worthy of belief could be founded upon it at all.
Are we then bound to believe that nature is absolutely and universally
uniform? Certainly not; we have no right to believe anything of this
kind. The rule only tells us that in forming beliefs which go beyond
our experience, we may make the assumption that nature is practically
uniform so far as we are concerned. Within the range of human action
and verification, we may form, by help of this assumption, actual
beliefs; beyond it, only those hypotheses which serve for the more
accurate asking of questions.