The Origination of Living Beings
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Thomas H. Huxley >> The Origination of Living Beings
This etext was prepared by Amy E. Zelmer.
THE METHOD BY WHICH THE CAUSES OF THE PRESENT AND PAST CONDITIONS OF
ORGANIC NATURE ARE TO BE DISCOVERED.--THE ORIGINATION OF LIVING BEINGS
by Thomas H. Huxley
In the two preceding lectures I have endeavoured to indicate to you the
extent of the subject-matter of the inquiry upon which we are engaged;
and now, having thus acquired some conception of the Past and Present
phenomena of Organic Nature, I must now turn to that which constitutes
the great problem which we have set before ourselves;--I mean, the
question of what knowledge we have of the causes of these phenomena of
organic nature, and how such knowledge is obtainable.
Here, on the threshold of the inquiry, an objection meets us. There are
in the world a number of extremely worthy, well-meaning persons, whose
judgments and opinions are entitled to the utmost respect on account of
their sincerity, who are of opinion that Vital Phenomena, and
especially all questions relating to the origin of vital phenomena, are
questions quite apart from the ordinary run of inquiry, and are, by
their very nature, placed out of our reach. They say that all these
phenomena originated miraculously, or in some way totally different from
the ordinary course of nature, and that therefore they conceive it to
be futile, not to say presumptuous, to attempt to inquire into them.
To such sincere and earnest persons, I would only say, that a question
of this kind is not to be shelved upon theoretical or speculative
grounds. You may remember the story of the Sophist who demonstrated to
Diogenes in the most complete and satisfactory manner that he could not
walk; that, in fact, all motion was an impossibility; and that Diogenes
refuted him by simply getting up and walking round his tub. So, in the
same way, the man of science replies to objections of this kind, by
simply getting up and walking onward, and showing what science has done
and is doing--by pointing to that immense mass of facts which have been
ascertained and systematized under the forms of the great doctrines of
Morphology, of Development, of Distribution, and the like. He sees an
enormous mass of facts and laws relating to organic beings, which stand
on the same good sound foundation as every other natural law; and
therefore, with this mass of facts and laws before us, therefore, seeing
that, as far as organic matters have hitherto been accessible and
studied, they have shown themselves capable of yielding to scientific
investigation, we may accept this as proof that order and law reign
there as well as in the rest of nature; and the man of science says
nothing to objectors of this sort, but supposes that we can and shall
walk to a knowledge of the origin of organic nature, in the same way
that we have walked to a knowledge of the laws and principles of the
inorganic world.
But there are objectors who say the same from ignorance and ill-will.
To such I would reply that the objection comes ill from them, and that
the real presumption, I may almost say the real blasphemy, in this
matter, is in the attempt to limit that inquiry into the causes of
phenomena which is the source of all human blessings, and from which
has sprung all human prosperity and progress; for, after all, we can
accomplish comparatively little; the limited range of our own faculties
bounds us on every side,--the field of our powers of observation is
small enough, and he who endeavours to narrow the sphere of our
inquiries is only pursuing a course that is likely to produce the
greatest harm to his fellow-men.
But now, assuming, as we all do, I hope, that these phenomena are
properly accessible to inquiry, and setting out upon our search into
the causes of the phenomena of organic nature, or, at any rate, setting
out to discover how much we at present know upon these abstruse
matters, the question arises as to what is to be our course of
proceeding, and what method we must lay down for our guidance. I reply
to that question, that our method must be exactly the same as that
which is pursued in any other scientific inquiry, the method of
scientific investigation being the same for all orders of facts and
phenomena whatsoever.
I must dwell a little on this point, for I wish you to leave this room
with a very clear conviction that scientific investigation is not, as
many people seem to suppose, some kind of modern black art. I say that
you might easily gather this impression from the manner in which many
persons speak of scientific inquiry, or talk about inductive and
deductive philosophy, or the principles of the "Baconian philosophy." I
do protest that, of the vast number of cants in this world, there are
none, to my mind, so contemptible as the pseudoscientific cant which is
talked about the "Baconian philosophy."
To hear people talk about the great Chancellor--and a very great man he
certainly was,--you would think that it was he who had invented
science, and that there was no such thing as sound reasoning before the
time of Queen Elizabeth. Of course you say, that cannot possibly be
true; you perceive, on a moment's reflection, that such an idea is
absurdly wrong, and yet, so firmly rooted is this sort of
impression,--I cannot call it an idea, or conception,--the thing is too
absurd to be entertained,--but so completely does it exist at the bottom
of most men's minds, that this has been a matter of observation with me
for many years past. There are many men who, though knowing absolutely
nothing of the subject with which they may be dealing, wish,
nevertheless, to damage the author of some view with which they think
fit to disagree. What they do, then, is not to go and learn something
about the subject, which one would naturally think the best way of
fairly dealing with it; but they abuse the originator of the view they
question, in a general manner, and wind up by saying that, "After all,
you know, the principles and method of this author are totally opposed
to the canons of the Baconian philosophy." Then everybody applauds, as
a matter of course, and agrees that it must be so. But if you were to
stop them all in the middle of their applause, you would probably find
that neither the speaker nor his applauders could tell you how or in
what way it was so; neither the one nor the other having the slightest
idea of what they mean when they speak of the "Baconian philosophy."
You will understand, I hope, that I have not the slightest desire to
join in the outcry against either the morals, the intellect, or the
great genius of Lord Chancellor Bacon. He was undoubtedly a very great
man, let people say what they will of him; but notwithstanding all that
he did for philosophy, it would be entirely wrong to suppose that the
methods of modern scientific inquiry originated with him, or with his
age; they originated with the first man, whoever he was; and indeed
existed long before him, for many of the essential processes of
reasoning are exerted by the higher order of brutes as completely and
effectively as by ourselves. We see in many of the brute creation the
exercise of one, at least, of the same powers of reasoning as that
which we ourselves employ.
The method of scientific investigation is nothing but the expression of
the necessary mode of working of the human mind. It is simply the mode
at which all phenomena are reasoned about, rendered precise and exact.
There is no more difference, but there is just the same kind of
difference, between the mental operations of a man of science and those
of an ordinary person, as there is between the operations and methods
of a baker or of a butcher weighing out his goods in common scales, and
the operations of a chemist in performing a difficult and complex
analysis by means of his balance and finely-graduated weights. It is
not that the action of the scales in the one case, and the balance in
the other, differ in the principles of their construction or manner of
working; but the beam of one is set on an infinitely finer axis than
the other, and of course turns by the addition of a much smaller
weight.
You will understand this better, perhaps, if I give you some familiar
example. You have all heard it repeated, I dare say, that men of
science work by means of Induction and Deduction, and that by the help
of these operations, they, in a sort of sense, wring from Nature
certain other things, which are called Natural Laws, and Causes, and
that out of these, by some cunning skill of their own, they build up
Hypotheses and Theories. And it is imagined by many, that the
operations of the common mind can be by no means compared with these
processes, and that they have to be acquired by a sort of special
apprenticeship to the craft. To hear all these large words, you would
think that the mind of a man of science must be constituted differently
from that of his fellow men; but if you will not be frightened by
terms, you will discover that you are quite wrong, and that all these
terrible apparatus are being used by yourselves every day and every
hour of your lives.
There is a well-known incident in one of Moliere's plays, where the
author makes the hero express unbounded delight on being told that he
had been talking prose during the whole of his life. In the same way,
I trust, that you will take comfort, and be delighted with yourselves,
on the discovery that you have been acting on the principles of
inductive and deductive philosophy during the same period. Probably
there is not one here who has not in the course of the day had occasion
to set in motion a complex train of reasoning, of the very same kind,
though differing of course in degree, as that which a scientific man
goes through in tracing the causes of natural phenomena.
A very trivial circumstance will serve to exemplify this. Suppose you
go into a fruiterer's shop, wanting an apple,--you take up one, and, on
biting it, you find it is sour; you look at it, and see that it is hard
and green. You take up another one, and that too is hard, green, and
sour. The shopman offers you a third; but, before biting it, you
examine it, and find that it is hard and green, and you immediately say
that you will not have it, as it must be sour, like those that you have
already tried.
Nothing can be more simple than that, you think; but if you will take
the trouble to analyze and trace out into its logical elements what has
been done by the mind, you will be greatly surprised. In the first
place, you have performed the operation of Induction. You found that,
in two experiences, hardness and greenness in apples go together with
sourness. It was so in the first case, and it was confirmed by the
second. True, it is a very small basis, but still it is enough to make
an induction from; you generalize the facts, and you expect to find
sourness in apples where you get hardness and greenness. You found
upon that a general law, that all hard and green apples are sour; and
that, so far as it goes, is a perfect induction. Well, having got your
natural law in this way, when you are offered another apple which you
find is hard and green, you say, "All hard and green apples are sour;
this apple is hard and green, therefore this apple is sour." That
train of reasoning is what logicians call a syllogism, and has all its
various parts and terms,--its major premiss, its minor premiss, and its
conclusion. And, by the help of further reasoning, which, if drawn
out, would have to be exhibited in two or three other syllogisms, you
arrive at your final determination, "I will not have that apple." So
that, you see, you have, in the first place, established a law by
Induction, and upon that you have founded a Deduction, and reasoned out
the special conclusion of the particular case. Well now, suppose,
having got your law, that at some time afterwards, you are discussing
the qualities of apples with a friend: you will say to him, "It is a
very curious thing,--but I find that all hard and green apples are
sour!" Your friend says to you, "But how do you know that?" You at
once reply, "Oh, because I have tried it over and over again, and have
always found them to be so." Well. if we were talking science instead
of common sense, we should call that an Experimental Verification. And,
if still opposed, you go further, and say, "I have heard from the
people in Somersetshire and Devonshire, where a large number of apples
are grown, that they have observed the same thing. It is also found to
be the case in Normandy, and in North America. In short, I find it to
be the universal experience of mankind wherever attention has been
directed to the subject." Whereupon, your friend, unless he is a very
unreasonable man, agrees with you, and is convinced that you are quite
right in the conclusion you have drawn. He believes, although perhaps
he does not know he believes it, that the more extensive Verifications
are,--that the more frequently experiments have been made, and results
of the same kind arrived at,--that the more varied the conditions under
which the same results have been attained, the more certain is the
ultimate conclusion, and he disputes the question no further. He sees
that the experiment has been tried under all sorts of conditions, as to
time, place, and people, with the same result; and he says with you,
therefore, that the law you have laid down must be a good one, and he
must believe it.
In science we do the same thing;--the philosopher exercises precisely
the same faculties, though in a much more delicate manner. In
scientific inquiry it becomes a matter of duty to expose a supposed law
to every possible kind of verification, and to take care, moreover,
that this is done intentionally, and not left to a mere accident, as in
the case of the apples. And in science, as in common life, our
confidence in a law is in exact proportion to the absence of variation
in the result of our experimental verifications. For instance, if you
let go your grasp of an article you may have in your hand, it will
immediately fall to the ground. That is a very common verification of
one of the best established laws of nature--that of gravitation. The
method by which men of science establish the existence of that law is
exactly the same as that by which we have established the trivial
proposition about the sourness of hard and green apples. But we
believe it in such an extensive, thorough, and unhesitating manner
because the universal experience of mankind verifies it, and we can
verify it ourselves at any time; and that is the strongest possible
foundation on which any natural law can rest.
So much by way of proof that the method of establishing laws in science
is exactly the same as that pursued in common life. Let us now turn to
another matter (though really it is but another phase of the same
question), and that is, the method by which, from the relations of
certain phenomena, we prove that some stand in the position of causes
towards the others.
I want to put the case clearly before you, and I will therefore show you
what I mean by another familiar example. I will suppose that one of
you, on coming down in the morning to the parlour of your house, finds
that a tea-pot and some spoons which had been left in the room on the
previous evening are gone,--the window is open, and you observe the mark
of a dirty hand on the window-frame, and perhaps, in addition to that,
you notice the impress of a hob-nailed shoe on the gravel outside. All
these phenomena have struck your attention instantly, and before two
minutes have passed you say, "Oh, somebody has broken open the window,
entered the room, and run off with the spoons and the tea-pot!" That
speech is out of your mouth in a moment. And you will probably add, "I
know there has; I am quite sure of it!" You mean to say exactly what
you know; but in reality what you have said has been the expression of
what is, in all essential particulars, an Hypothesis. You do not 'know'
it at all; it is nothing but an hypothesis rapidly framed in your own
mind! And it is an hypothesis founded on a long train of inductions
and deductions.
What are those inductions and deductions, and how have you got at this
hypothesis? You have observed, in the first place, that the window is
open; but by a train of reasoning involving many Inductions and
Deductions, you have probably arrived long before at the General
Law--and a very good one it is--that windows do not open of themselves;
and you therefore conclude that something has opened the window. A
second general law that you have arrived at in the same way is, that
tea-pots and spoons do not go out of a window spontaneously, and you
are satisfied that, as they are not now where you left them, they have
been removed. In the third place, you look at the marks on the
window-sill, and the shoemarks outside, and you say that in all
previous experience the former kind of mark has never been produced by
anything else but the hand of a human being; and the same experience
shows that no other animal but man at present wears shoes with
hob-nails on them such as would produce the marks in the gravel. I do
not know, even if we could discover any of those "missing links" that
are talked about, that they would help us to any other conclusion! At
any rate the law which states our present experience is strong enough
for my present purpose.--You next reach the conclusion, that as these
kinds of marks have not been left by any other animals than men, or are
liable to be formed in any other way than by a man's hand and shoe, the
marks in question have been formed by a man in that way. You have,
further, a general law, founded on observation and experience, and
that, too, is, I am sorry to say, a very universal and unimpeachable
one,--that some men are thieves; and you assume at once from all these
premisses--and that is what constitutes your hypothesis--that the man
who made the marks outside and on the window-sill, opened the window,
got into the room, and stole your tea-pot and spoons. You have now
arrived at a 'Vera Causa';--you have assumed a Cause which it is plain
is competent to produce all the phenomena you have observed. You can
explain all these phenomena only by the hypothesis of a thief. But
that is a hypothetical conclusion, of the justice of which you have no
absolute proof at all; it is only rendered highly probable by a series
of inductive and deductive reasonings.
I suppose your first action, assuming that you are a man of ordinary
common sense, and that you have established this hypothesis to your own
satisfaction, will very likely be to go off for the police, and set
them on the track of the burglar, with the view to the recovery of your
property. But just as you are starting with this object, some person
comes in, and on learning what you are about, says, "My good friend,
you are going on a great deal too fast. How do you know that the man
who really made the marks took the spoons? It might have been a monkey
that took them, and the man may have merely looked in afterwards." You
would probably reply, "Well, that is all very well, but you see it is
contrary to all experience of the way tea-pots and spoons are
abstracted; so that, at any rate, your hypothesis is less probable than
mine." While you are talking the thing over in this way, another friend
arrives, one of that good kind of people that I was talking of a little
while ago. And he might say, "Oh, my dear sir, you are certainly going
on a great deal too fast. You are most presumptuous. You admit that
all these occurrences took place when you were fast asleep, at a time
when you could not possibly have known anything about what was taking
place. How do you know that the laws of Nature are not suspended
during the night? It may be that there has been some kind of
supernatural interference in this case." In point of fact, he declares
that your hypothesis is one of which you cannot at all demonstrate the
truth, and that you are by no means sure that the laws of Nature are
the same when you are asleep as when you are awake.
Well, now, you cannot at the moment answer that kind of reasoning. You
feel that your worthy friend has you somewhat at a disadvantage. You
will feel perfectly convinced in your own mind, however, that you are
quite right, and you say to him, "My good friend, I can only be guided
by the natural probabilities of the case, and if you will be kind enough
to stand aside and permit me to pass, I will go and fetch the police."
Well, we will suppose that your journey is successful, and that by good
luck you meet with a policeman; that eventually the burglar is found
with your property on his person, and the marks correspond to his hand
and to his boots. Probably any jury would consider those facts a very
good experimental verification of your hypothesis, touching the cause
of the abnormal phenomena observed in your parlour, and would act
accordingly.
Now, in this suppositious case, I have taken phenomena of a very common
kind, in order that you might see what are the different steps in an
ordinary process of reasoning, if you will only take the trouble to
analyse it carefully. All the operations I have described, you will
see, are involved in the mind of any man of sense in leading him to a
conclusion as to the course he should take in order to make good a
robbery and punish the offender. I say that you are led, in that case,
to your conclusion by exactly the same train of reasoning as that which
a man of science pursues when he is endeavouring to discover the origin
and laws of the most occult phenomena. The process is, and always must
be, the same; and precisely the same mode of reasoning was employed by
Newton and Laplace in their endeavours to discover and define the
causes of the movements of the heavenly bodies, as you, with your own
common sense, would employ to detect a burglar. The only difference
is, that the nature of the inquiry being more abstruse, every step has
to be most carefully watched, so that there may not be a single crack
or flaw in your hypothesis. A flaw or crack in many of the hypotheses
of daily life may be of little or no moment as affecting the general
correctness of the conclusions at which we may arrive; but, in a
scientific inquiry, a fallacy, great or small, is always of importance,
and is sure to be constantly productive of mischievous, if not fatal
results.
Do not allow yourselves to be misled by the common notion that an
hypothesis is untrustworthy simply because it is an hypothesis. It is
often urged, in respect to some scientific conclusion, that, after all,
it is only an hypothesis. But what more have we to guide us in
nine-tenths of the most important affairs of daily life than hypotheses,
and often very ill-based ones? So that in science, where the evidence
of an hypothesis is subjected to the most rigid examination, we may
rightly pursue the same course. You may have hypotheses and
hypotheses. A man may say, if he likes, that the moon is made of green
cheese: that is an hypothesis. But another man, who has devoted a
great deal of time and attention to the subject, and availed himself of
the most powerful telescopes and the results of the observations of
others, declares that in his opinion it is probably composed of
materials very similar to those of which our own earth is made up: and
that is also only an hypothesis. But I need not tell you that there is
an enormous difference in the value of the two hypotheses. That one
which is based on sound scientific knowledge is sure to have a
corresponding value; and that which is a mere hasty random guess is
likely to have but little value. Every great step in our progress in
discovering causes has been made in exactly the same way as that which I
have detailed to you. A person observing the occurrence of certain
facts and phenomena asks, naturally enough, what process, what kind of
operation known to occur in nature applied to the particular case, will
unravel and explain the mystery? Hence you have the scientific
hypothesis; and its value will be proportionate to the care and
completeness with which its basis had been tested and verified. It is
in these matters as in the commonest affairs of practical life: the
guess of the fool will be folly, while the guess of the wise man will
contain wisdom. In all cases, you see that the value of the result
depends on the patience and faithfulness with which the investigator
applies to his hypothesis every possible kind of verification.
I dare say I may have to return to this point by-and-by; but having
dealt thus far with our logical methods, I must now turn to something
which, perhaps, you may consider more interesting, or, at any rate,
more tangible. But in reality there are but few things that can be
more important for you to understand than the mental processes and the
means by which we obtain scientific conclusions and theories.1 Having
granted that the inquiry is a proper one, and having determined on the
nature of the methods we are to pursue and which only can lead to
success, I must now turn to the consideration of our knowledge of the
nature of the processes which have resulted in the present condition of
organic nature.