THEORIES HOW REACHED AND USED
Educated guessing . . . Weaving power . . . Imagination
indispensable . . . The proving process . . . Theory gainfully
directs both observation and experiment . . . Professor Tyndall’s
views . . . Discursiveness illustrated in Thomas Young.
Theories as Finder Thoughts.
As far back as the first man with brains in his head, there was an ache
to know why the sun shone, the stars twinkled, the winds blew, why
harvests here were plentiful and there scant. The whole burden of
witchcraft, of fetichism, of beliefs in voodoo, is a pathetic proof of
this human longing to explain. What, after all, are superstitions but
premature explanations that overstay their time? When men of thought get
a glimpse of an interpretation really true, they are eager to prolong
that glimpse until it becomes a survey whose due tests confirm and
buttress a well grounded anticipation. This exploring process reminds us
of what took place long ago when an architect of unexampled boldness
first imagined a dome for a temple, and brought his dream to fulfilment.
He began by rearing a single arch, fairly strong, yet hardly strong
enough; a second arch arose to meet the first at their common crest;
now, in mutual support both had a stability neither could display alone;
at last when the wall had gone full circle it had a strength vastly
greater than that of any part by itself. The long-admired arch had
indeed become no more than an element to be joined with other arches to
create a unit of an order distinctly higher.
For ages the men who studied nature looked upon it as little changed
since it left its Maker’s hand. Of infinite stimulus was the perception
that it is a drama, not a tableau, which spreads itself before the eye.
Speedily and with incomparable instruction it was traced how every
actor in that drama had been molded by the part it had played in
maintaining itself upon the stage of life. Every rival, parasite or foe,
every stress of climate, was studied in its influence on food or frame,
while the ever-threatened doom for irresponsiveness was the extinction
which befell countless forms once masters of the earth. No hue of scale
or feather, no barb or tusk, no curve of beak or note of song but served
a purpose in the plot or advanced the action in some conflict to the
death. When Darwin was confronted in plant or beast by an organ or a
habit which puzzled him, he was wont to ask, What use can this have had?
And seldom was the question asked in vain. He laid great stress on the
directive worth of a well-considered theory. He tells us, “I am a firm
believer that without speculation there is no good and original
observation.” In a letter he remarks, “It is an old and firm conviction
of mine that the naturalists who accumulate facts and make many partial
generalizations are the _real_ benefactors of science. Those who merely
accumulate facts I cannot very much respect.”
In rising from facts to explanations a weighty debt is due to modern
aids to eyes and hands. To men who knew only what direct vision could
tell them in a single life-time, it was but natural to repeat:--“The
thing that hath been, is that which shall be; and that which is done, is
that which shall be done; and there is no new thing under the sun.” But
we of to-day are in different case. The astronomer, joining camera to
telescope, lengthens the diameter of the known universe a thousand-fold;
he discovers system after system in stages of life such as our sun and
its attendant orbs have passed through in ages so remote as to refuse
computation. And many types of nebulae and stars are now studied which
were never so much as imagined until they revealed themselves upon the
photographic plate. Meanwhile the geologist, examining the closely
welded ribs of our globe, comparing the birds, beasts and men of to-day
with their earliest known ancestry, believes that the earth has been a
scene of life for a million centuries or more. As we restore one act
after another in this great cosmical drama, we are able to forecast
those which may next appear. Because the whole scheme of things from
centre to rim pulses in one ethereal ocean, every actor has interplay
with every other, so that the sweep of events discloses a unity all the
more intimate the more closely it is studied. At this hour physicists
and chemists, with electricity their new servant at command, are
gathering proof that what have long been called “elements,” are probably
one substance, variously assembled, moving at speeds and in paths
infinitely diverse, repeating in little the mighty swings of suns and
planets. Throughout these researches a constant spur is the thought that
here may be traced such processes of development as have been laid bare
in every other province of nature. From circumference to centre,
evolution is the master key of each keen questioner.
Modern Views of Matter.
Organic nature to the modern interpreter is thus alive through and
through. In his view atom and molecule are also alive in a subordinate,
elemental degree. Indeed, he thinks, it is their life borne in air,
water and food which in plant or animal rises to new planes of dignity.
He looks afresh at the broken alum crystal which repairs itself in a
solution, and sees there the removal of the imaginary fence which long
divided organic nature from inorganic. (See illustration, page 194.) It
was a shrewd guess of Sir Isaac Newton that the diamond is combustible;
he did not suspect it to be carbon, but he knew it to be highly
refrangible as are many combustible bodies. His conjecture shows him
taking the first step toward the current view that properties, the modes
of behavior of matter, are not passive qualities, but are due to real
activities; that what a substance is depends upon how its ultimate parts
move. Clausius and Maxwell in a theory which marks a new era explained
the elasticity of gases as manifested in the ceaseless motion of their
molecules, declaring that an ounce of air within a fragile jar is able
to sustain the pressure of the atmosphere around it, because the air,
though only an ounce in weight, dashes against its container with an
impact forcible enough to balance the external pressure. Proof whereof
appears in measuring the velocity of air as it rushes into a vacuum.
Here a significant point is that in leaving the realm of mass-mechanics,
where the tax of friction is inexorable, we enter a sphere where the
swiftest motion may go on forever without paying friction the smallest
levy.
Elasticity Explained.
Elasticity of solids is explained on the same principle. If we swiftly
turn a gyroscopic wheel we can only change its plane of rotation by an
effort, which effort is repaid when the metal is allowed to resume its
original plane of motion. It is imagined that in like manner the
particles in an elastic spring move rapidly in a definite plane; if
deflected therefrom they oppose resistance and are ready to do work in
returning thereto. Of kindred to the kinetic theory of elasticity is the
explanation of heat as a distinct and ceaseless molecular motion on
which the dimensions of masses depend. It has long seemed to me that
every case of “potential” energy, as that of a spring bent or coiled,
may in like manner embody actual though impalpable and invisible motion.
I presented this view in the Popular Science Monthly, December, 1876.
The very constitution of matter is now referred to the motions, highly
diversified, of the simplest substance possible. Helmholtz, Lord Kelvin,
and Professor Clerk Maxwell have imagined the molecules of lead, iron,
or other element as vortices born of the ether in which without
resistance they forever whirl. As we see in the case of a quickly
rotated chain, substantial rigidity is conferred by motion sufficiently
swift. Nor are molecules without somewhat of individuality. We are wont
to think of masses of solid iron as precisely similar in quality, but
experience shows us that one bar of iron may vary from another by all
that has differenced the history of the two. A careful workman uses a
steel die for only a short service before he returns it to the annealer,
well assured that the metal, despite its seeming wholeness, has suffered
severe internal strain at every blow, which, were no caution exercised,
would soon reveal itself in fracture of the die, or ruined work. Facts
of this kind, which every day confront the mechanic and engineer, convey
a prophecy of the sensibility and memory which dawn with life.
Guesses and Proof.
A theory helpful to the observer or the experimenter comes at last, in
many cases, from much guessing. The theorist fills his mind with facts,
broods over them, endeavors to explain them, but whether his theory is
true or false must be decided solely by proof. This point was clearly
stated by Dr. Pye-Smith, of London, in his Harveian oration, 1893:--“As
Paley justly puts it, he only discovers who proves. To hit upon a true
conjecture here and there, amid a crowd of untrue, and leave it again
without appreciation of its importance, is a sign, not of intelligence,
but of frivolity. We are told that of the seven wise men of Greece, one
(I believe it was Thales) taught that the sun did not go around the
earth, but the earth around the sun. Hence it has been said that Thales
anticipated Copernicus--a flagrant example of the fallacy in question. A
crowd of idle philosophers who sat through the long summer days and
nights of Attica discussing all things in heaven and earth must
sometimes have hit upon a true opinion, if only by accident, but Thales,
or whoever broached the heliocentric dogma, had no reason for his belief
and showed himself not more, but less, reasonable than his companions.
The crude theories and gross absurdities of phrenology are not in the
least justified or even excused by the present knowledge of cerebral
localization; nor do the baseless speculations of Lamarck and Erasmus
Darwin entitle them to be regarded as the forerunners of Charles Darwin.
Up to 1859 impartial and competent men were bound to disbelieve in
evolution. After that date, or at least, so soon as the facts and
arguments of Darwin and Wallace had been published, they were equally
bound to believe in it. He discovers who proves, and by this test Harvey
is the sole and absolute discoverer of the movements of the heart and of
the blood.”
The Knitting Faculty.
Discovery is the reward of diligence, such as that of Harvey, but not of
diligence alone. Professor William James, in his Psychology
remarks:--“The inquirer starts with a fact of which he sees the reason,
or a theory of which he sees the proof. In either case he keeps turning
the matter incessantly in his mind, until by the arousal of associate
upon associate, some habitual, some similar, one arises which he
recognizes to suit his need. This, however, may take years. No rules can
be given by which the investigator can proceed straight to his result;
but both here and in the case of reminiscence the accumulation of helps
in the way of associations may advance more rapidly by the use of
certain methods. In striving to recall a thought, for example, we may
of set purpose run through the successive classes of circumstances with
which it may possibly have been connected, trusting that when the right
member of the class has turned up it will help the thought’s revival.
. . . In scientific research this accumulation of associates has been
methodized by Mill as ‘four methods of experimental inquiry.’ By the
method of Agreement, of Difference, of Residues, and of Concomitant
Variations, we make certain lists of cases, and by ruminating these
lists in our minds the cause we seek will be more likely to emerge. But
the final stroke of discovery is only prepared, not effected by them.
The brain tracts must, of their own accord, shoot the right way at last,
or we shall still grope in darkness.”
The Detection of Likeness Beneath Diversity.
Among the talents of the discoverer, perhaps the chief is to detect
similarity in phenomena which, to casual observation, are unlike. Of
this the capital example is Franklin’s proof that lightning and common
frictional electricity are one and the same. Professor Alexander Bain,
in “The Senses and the Intellect,” thus describes this talent:--“When it
first occurred to a reflecting mind that moving water had a property
identical with human or brute force, namely, the property of setting
other masses in motion, overcoming resistance and inertia--when the
sight of the stream suggested through this point of likeness the power
of the animal--a new addition was made to the class of prime movers, and
when circumstances permitted, this power could be made a substitute for
the others. It may seem to the modern understanding, familiar with
water-wheels and drifting rafts, that the similarity here was an
extremely obvious one. But if we put ourselves back into an early state
of mind, when running water affected the mind by its brilliancy, its
roar, and irregular devastation, we may easily suppose that to identify
this with animal muscular energy was by no means an obvious effect.
Doubtless when a mind arose, insensible by natural constitution to the
superficial aspects of things, and having withal a great stretch of
identifying intellect, such a comparison would then be possible. We may
pursue the same example one stage further, and come to the discovery of
steam-power, or the identification of expanding vapor with the
previously known sources of mechanical force. To the common eye, for
ages, vapor presented itself as clouds in the sky; or, as a hissing
noise at the spout of a kettle, with the formation of a foggy, curling
cloud at a few inches’ distance. The forcing up of the lid of a kettle
may also have been occasionally observed. But how long was it ere any
one was struck with parallelism of this appearance with a blast of wind,
a rush of water, or an exertion of animal muscle? The discordance was
too great to be broken through by such a faint and limited amount of
likeness. In one mind, however, the identification did take place, and
was followed out into its consequences. The likeness had occurred to
other minds previously, but not with the same results. Such minds must
have been in some way or other distinguished above the millions of
mankind, and we are endeavoring to give an explanation of their
superiority. The intellectual character of Watt contained all the
elements preparatory to a great stroke of similarity in such a case--a
high susceptibility, both by nature and education, to the mechanical
properties of bodies; ample previous knowledge, or familiarity; and
indifference to the superficial and sensational effects of things. It is
not only possible, however, but exceedingly probable, that many men
possessed all these accomplishments; they are of a kind not transcending
common abilities. They would in some degree attach to a mechanical
education, as a matter of course. That the discovery was not sooner made
supposes that something farther, and not of common occurrence was
necessary; and this additional endowment appears to be the identifying
power of similarity in general; the tendency to detect likeness in the
midst of disparity and disguise. This supposition accounts for the fact,
and is consistent with the known intellectual character of the inventor
of the steam engine.”
The Part Played by Imagination.
A discoverer needs for success much more than identifying power.
Professor John Tyndall, one of the chief expositors of science in the
nineteenth century, speaks thus of the part played by an investigator’s
imagination:--
“How are the hidden things of nature to be revealed? How, for example,
are we to lay hold of the physical basis of light, since, like that of
life itself, it lies entirely outside the domain of the senses? Now
philosophers may be right in affirming that we cannot transcend
experience. But we can, at all events, carry it a long way from its
origin. We can also magnify, diminish, qualify, and combine experiences,
so as to render them fit for purposes entirely new. We are gifted with
the power of Imagination, and by this power we can lighten the darkness
which surrounds the world of the senses. There are tories even in
science who regard imagination as a faculty to be feared and avoided
rather than employed. They had observed its action in weak vessels and
were unduly impressed by its disasters. But they might with equal
justice point to exploded boilers as an argument against the use of
steam. Bounded and conditioned by co-operative reason, imagination
becomes the mightiest instrument of the physical discoverer. Newton’s
passage from a falling apple to a falling moon was, at the outset, a
leap of the imagination. When William Thomson tries to place the
ultimate particles of matter between his compass points, and to apply to
them a scale of millimeters, he is powerfully aided by this faculty. And
in much that has recently been said about protoplasm and life, we have
the outgoings of the imagination guided and controlled by the known
analogies of science. In fact, without this power, our knowledge of
nature would be a mere tabulation of co-existences and sequences. We
should still believe in the succession of day and night, of summer and
winter; but the soul of Force would be dislodged from our universe;
causal relations would disappear, and with them that science which is
now binding the parts of nature into an organic whole.”
Professor Tyndall also tells us how sound theories are divided from
unsound:--
Theories Must be Verified.
“From a starting-point furnished from his own researches or those of
others, the investigator proceeds by combining intuition and
verification. He ponders the knowledge he possesses and tries to push it
further, he guesses and checks his guess, he conjectures and confirms or
explodes his conjecture. These guesses and conjectures are by no means
leaps in the dark; for knowledge once gained casts a faint light beyond
its own immediate boundaries. There is no discovery so limited as not
to illuminate something beyond itself. The force of intellectual
penetration into this penumbral region which surrounds actual knowledge
is not, as some seem to think, dependent upon method, but upon the
genius of the investigator. There is, however, no genius so gifted as
not to need control and verification. The profoundest minds know best
that Nature’s ways are not at all times their ways, and that the
brightest flashes in the world of thought are incomplete until they have
been proved to have their counterparts in the world of fact. Thus the
vocation of the true experimentalist may be defined as the continued
exercise of spiritual insight, and its incessant correction and
realization. His experiments constitute a body, of which his purified
intuitions are, as it were, the soul.”
Theories, however helpful, should be held with a loose hand. He
declares:--
“In our conceptions and reasonings regarding the forces of nature, we
perpetually make use of symbols which, whenever they possess a high
representative value we dignify with the name of theories. Thus,
prompted by certain analogies, we ascribe electrical phenomena to the
action of a peculiar fluid, sometimes flowing, sometimes at rest. Such
conceptions have their advantages and their disadvantages; they afford
peaceful lodging to the intellect for a time, but they also circumscribe
it, and by-and-by, when the mind has grown too large for its lodging, it
often finds difficulty in breaking down the walls of what has become its
prison instead of its home.”
In the same vein was the remark of Michael Faraday:--“I cannot but doubt
that he who as a mere philosopher has most power of penetrating the
secrets of nature, and guessing by hypothesis at her mode of working,
will also be most careful for his own safe progress and that of others,
to distinguish the knowledge which consists of assumption, by which I
mean theory and hypothesis, from that which is the knowledge of facts
and laws.”
He once wrote a letter on ray-vibrations to Mr. Richard Phillips; at its
close he said:--“I think it likely that I have made many mistakes in the
preceding pages, for even to myself my ideas on this point appear only
as the shadow of a speculation, or as one of those impressions on the
mind which are allowable for a time as guides to thought and research.
He who labors in experimental inquiries, knows how numerous these are,
and how often their apparent fitness and beauty vanish before the
progress and development of real natural truth.”
“Summing up, then,” says Professor William Stanley Jevons, in
“Principles of Science,” “it would seem as if the mind of the great
discoverer must combine almost contradictory attributes. He must be
fertile in theories and hypotheses, and yet full of facts and precise
results of experience. He must entertain the feeblest analogies, and the
merest guesses at truth, and yet he must hold them worthless until they
are verified in experiment. When there are any grounds of probability he
must hold tenaciously to an old opinion, and yet he must be prepared at
any moment to relinquish it when a single clear contradictory fact is
encountered. ‘The philosopher,’ says Faraday, ‘should be a man willing
to listen to every suggestion, but determined to judge for himself. He
should not be biassed by appearances; have no favorite hypotheses; be of
no school; and in doctrine have no master. He should not be a respecter
of persons, but of things. Truth should be his primary object. If to
these qualities be added industry, he may indeed hope to walk within the
veil of the temple of nature.’”
Character, no less than mind of the highest order, ever distinguishes
the great researcher. Says Professor Tyndall:--“Those who are
unacquainted with the details of scientific investigation, have no idea
of the amount of labor expended on the determination of those numbers on
which important calculations or inferences depend. They have no idea of
the patience shown by a Berzelius in determining atomic weights; by a
Regnault in determining co-efficients of expansion; or of a Joule in
determining the mechanical equivalent of heat. There is a morality
brought to bear upon such matters, which, in point of severity, is
probably without a parallel in any other domain of intellectual action.”
Surely there was a union of the highest character and of consummate
ability in Stas, the Belgian chemist, who eliminated from his chemicals
every trace of that pervasive element, sodium, so thoroughly, that even
its spectroscopic detection was impossible.
A Word for Discursiveness.
The greatest man of science that England has given to the world was Sir
Isaac Newton, second only to him was Dr. Thomas Young, who established
the wave-theory of light, who deciphered Egyptian hieroglyphics with
marvelous skill, and was withal an accomplished physician. In 1801 he
was appointed to the professorship of natural philosophy in the Royal
Institution, London, founded in 1800 by Benjamin Thompson, Count
Rumford, a native of Woburn, Massachusetts. When Dr. Young died, Davies
Gilbert, president of the Royal Society, delivered a commemorative
address in the course of which he declared that in Young’s opinion it is
probably most advantageous to mankind that the researches of some
inquirers should be concentrated within a given compass, but that others
should pass more rapidly through a wider range. He believed that the
faculties of the mind were more exercised, and probably rendered
stronger, by going beyond the rudiments, and overcoming the great
elementary difficulties, of a variety of studies, than by employing the
same number of hours in any one pursuit--that the doctrine of the
division of labor, however applicable to material product, was not so to
intellect; and that it went to reduce the dignity of man in the scale of
rational existences. He thought it impossible to foresee the
capabilities of improvement in any science, so much of accident having
led to the most important discoveries, that no man could say what might
be the comparative advantage of any one study rather than of another;
though he would have scarcely recommended the plan of his own course as
a model to others, he still was satisfied in the method which he had
pursued.