Part 3

Yet what, actually, is the process of exact science? The answer to this question should show us whether or not the term does have any precise and limited significance, and whether or not fundamental confusion must result from the attempt to make it synonymous with all knowledge.

Exact science, then, is first of all based on the naïve belief in an objective and real world whose events are connected in an orderly and prescribed manner, and occur independently of our thought or will. The phenomena of this objective world appeal to us through our sense-organs by some form of action, which we call energy, and are interpreted by our minds. We speak of this interpretation as observation; but to be scientific we must also select the phenomena to be observed, in order that we may classify their similarities and their dissimilarities. In the course of time, we have found such precision in many of our classifications and such regularity in the past actions of phenomena, that we are able to predict future events. Those predictions, which from past experience we find to have been accurately verified, we formulate as laws. For example, we have observed the actions of so many falling bodies that we have formulated the law of gravitation. It would be an error to say that a body fell, yesterday, because of this law; that event was simply one of the observed facts from which the law was deduced; but it is quite proper to predict that such a body will fall, to-morrow, in accordance with the law of gravitation. To sum up, the scientific method is limited to experimental observation and the formulation of laws; its value lies in the fact that, by its cultivation, we have done much to allay our apprehensions for the future and thus have abated the edge of superstition; and we also have vastly increased our power over our environment, or, in the much misunderstood aphorism of Francis Bacon, we have found science to be valuable for its fruits.

In a general way, we may say that the scientist should follow in his investigations the phenomena of the objective world only until their special forms of energy are absorbed by our nervous system. It is in the province of the humanist to study the phenomena of the subjective world after these stimuli have been translated into emotion and thought.

If a scientific prediction, or law, is to be something more than a vague statement of what will probably occur, we feel the necessity of measuring the quantity of the event; that is, our minds are not satisfied until we are able to express it mathematically. Since the only measurable attributes, concerning which our opinion of more or less is definite, are geometrical lengths, the aim of all science is, and must be, to express its laws in the language of mechanics; for that subject alone deals exclusively with simple, sensible masses and their geometrical relations in space. We have then the paradox that while mathematics is the goal of science, in that it is the ideal method, or language of expression, it is not itself a science since it is concerned with subjective ideas and is not limited by the restrictions of sensible bodies. Modern men of science may rebel against this fact; but even the newer, and more dubious, of the pseudo-sciences are forced to substantiate their claims with the support of factitious mathematical formulæ and tables and to simulate the mechanistic method. The inevitable tendency of science is to investigate all phenomena quantitatively, and to view the whole universe as a vast and measurable machine.

If the phenomena of life are to be classed as an exact science, it is necessary to postulate that the living organism, also, is a machine,--a thing of various material parts, acting on each other by mechanical forces. Such a postulate is pure fiat, for we have found no common factors between what we call vital actions and mechanical and physical forces. Biology is, at best, confined to the discovery of qualitative classifications, and the mutual chemical and physical reactions of the organism; and life is so complex and so variable that very few of its phenomena can be predicted with any accuracy. For example, the so-called law of heredity is often cited, but we have made scarcely any progress towards predicting variations in even an immediately succeeding generation. Even if a general law of progressive evolution were granted to have been established, no one could foretell by it the future variations of any species.

If the scientific method is badly strained when applied to even the simplest forms of life, it completely fails when used to elucidate the phenomena of the mind. The fundamental definition of science excludes the processes of consciousness from its field, for it assumes that objective phenomena are to be interpreted by the mind. If we attempt to study the mind objectively, then we come face to face with the absurd paradox of a thing investigating itself by means of I itself. And the gibe cast at the scientific psychologists, that they propose to study the mind by first denying its existence, is only too well founded.

The possibility of a scientific method is based on a rational interpretation of objective phenomena. Psychology, as a science, would be a solemn version of Alice Through the Looking Glass in which real persons are viewed and analysed by their images, or rather by some other intelligence, such as a dog or an inhabitant of Mars. The futility of such a process should be apparent if we recollect that an animal’s mental processes can themselves be estimated and expressed only as a vaguer and more rudimentary sort of human mind.

Our modern idea that science embraces all kinds of knowledge is, as I have mentioned before, a curious reversion to the Greeks. In spite of the fact that they formulated the great deductive laws of physics, such as cause and effect, conservation of matter, etc., and developed an extraordinarily fruitful science of geometry, they remained indifferent to the experimental method. They developed almost no apparatus for experimentation, established no standards of measurement, and their arithmetical symbols were so awkward that only the simplest calculations could be made. They never succeeded in disentangling subjective and objective ideas. Plato could anticipate the modern conception of natural law in his aphorism that God geometrises, but at the same time he vaguely identified the human soul with the stars and endued the universe with life. Democritus pictured the world as an aggregation of atoms, differing only in size, shape, and motion; yet he also tacitly ascribed to them a will or desire to move which was only less pronounced than in those finer particles which constituted the souls of men. Also the four classic elements,--earth, water, air, and fire,--which combined in different proportions to form all material bodies, were actuated by the animistic principle that each element sought its own place. One could multiply these examples of classical thought which confused mechanical forces with the vital attributes of will and desire.

The failure of the Greeks to develop an objective and experimental method was intensified by the domination of the Christian religion during the Middle Ages. The emphasis of thought was placed on the problems of human character. At a time when men were taught that our environment was a trap set by the powers of evil to allure our souls to eternal damnation, there could be little stimulus to study the laws of nature or to apply them to increase our interest in a temporal life. It is customary for historians to condemn the Church for having crushed science, but no concerted opposition was necessary in a society which saw no advantage in gathering its fruits. It was an axiom that truth was the direct consequence of intuition and revelation, that God had revealed in the Bible, and through His living Church, all the knowledge necessary for man’s guidance in a transitory state. To neglect such a certainty for the perceptions of our fallible and sinful senses, and to construct a world from them according to our reason, would be to fall into the sin of the pride of the intellect. Furthermore, in a society small in numbers and in area, where the greater number were believed to have been created to minister to the comfort of the few, little need was felt for mechanical power and industry. The only science which seemed to be worth cultivating was one which was believed to foretell human events and to affect our spiritual life.

It had been generally accepted from ancient times that the stars influenced our lives and foretold the future. Such knowledge was eagerly sought by a society which was principally concerned with religion and was, at the same time, a prey to superstitious fear. It is not surprising that astrology was seriously cultivated. If we grant the postulate that the stars do affect us, then we must admit that astrology was a true science. The positions and the motions of the planets and stars were observed and recorded as accurately as possible, and deductions were made according to rules and laws believed to have been verified by experience. Nor does it seem to me much more credulous to believe that our character is determined by the relative positions of the planets, than to assume, as do Mr. Watson and the modern behaviourists, that our thoughts are caused by the relative positions and motions of the material atoms which happen to compose the substance of our brains. The astrologists had, at least, the great advantage of dealing with real bodies which we can observe, while these psychologists have for their use only the hypothetical and machine-made atoms of the chemist which they can never hope to observe. There is little to choose between the superstition that the planets foretell our characters and the superstition that atoms constitute thought; both lead to equally foolish and irrational practices. And there is the less excuse for the psychologist, since he has had the benefit of a longer past experience than had the astrologer to convince him of the futility of identifying mind and matter.

The only other science which aroused popular interest was alchemy. The basis of this subject was the postulate that all matter was composed of the four elements combined in various proportions. By the use of chemical reagents, the combinations of these elements could be altered and a given substance be thus changed into another. Alchemy is generally associated with the attempt to transmute metals and, in particular, to change lead into gold, because the natural cupidity of their patrons made it advisable for the alchemists to hold that prospect before them in order to obtain a livelihood. In principle, alchemy is but little different from modern chemistry. Our most recent theory still holds that the difference between lead and gold is due only to the numerical relations of a single element, the electron. The difference between chemistry and alchemy does not lie in either their fundamental hypotheses or their methods, but in our vastly superior technique of experimentation and accumulated knowledge. The nature of the modern electronic atom is essentially as fictitious as was the nature of the mediæval elements.

Besides exciting the hope of wealth, alchemy was important as an aid to health and longevity. Since health required that the four elements of the body should be preserved in their proper balance, illness, and even death, were but the temporary or permanent loss of their right proportions. Alchemists, convinced of this truth, were led to seek for a sovereign substance, the philosopher’s stone, which would have the power to restore this disturbed balance and give to its fortunate owner permanent health and life.

It is a mistake to suppose that the Church oppressed these sciences--many of its most orthodox fathers and saints eagerly studied them. The abuses due to the rampant charlatanry of many of their practitioners were repressed, but their serious doctrines were fused into the religion of the time much as, in our day, the clergy have tried to harmonise Christianity and biological evolution. In fact, as we shall see, the most determined opposition which the new Copernican theory of the solar system had to overcome was the fusion of Christian dogma with Aristotelian astrology and alchemy.

It was natural that the first fruits of the new science of the Renaissance should have been in astronomy and mechanics. The accumulated observations of the astrologers had vastly increased the complexity of the Ptolemaic system, and the discrepancies between the observed and calculated positions of the planets had become glaringly evident. When the great treatise of Copernicus was finally published as he lay on his death-bed, it is altogether probable that no one suspected that it marked the beginning of a new philosophy. He had merely proved that the calculations of astronomers were greatly simplified by assuming that the sun, instead of the earth, was the fixed centre of the solar system, and that the earth and other planets revolved about it in circular orbits. It must remain a mooted question whether Copernicus believed that his discovery was only a mathematical device; his book states explicitly that he, as a Catholic, still subscribed to the belief that the earth was actually the fixed centre of the universe as the Church and the Aristotelians both taught to be a necessary article of faith. At all events, it was not until Galileo some sixty years later invented the telescope and turned it on the heavens, that men saw the significance of the discovery. The eye of the telescope penetrated the depths of the solar system. It proved that the planets were not pure celestial matter but were mere masses like the earth. Their brilliance was not a divine fire but ordinary sunlight reflected from their dull surfaces; they, like the earth, were inanimate bodies revolving about the sun and the Copernican system became a fact instead of a mathematic device. It is not extravagant to assert that, with the acceptance of Copernican astronomy, the whole mediæval conception of nature gave place to a reliance on experimental evidence.

The work of Galileo in founding the science of mechanics was fatal to the mysticism of the contemporary alchemists. Instead of the elements with their natural places, their likes and dislikes, their hierarchy of nobility, and their subserviency to planetary influences, he laid down the universal principle that all natural actions were due to mechanical forces whose only function was to alter the motions of bodies and whose amount was measurable in mathematical symbols. His significant work for us was an uncompromising war waged against the scientific dogmatism of the Aristotelians on the clear-cut issue that knowledge of the objective world could be obtained only by experimental evidence, and not by subjective preconceptions. Understood rightly, he had reinstated the Platonic dualism of two worlds, one of matter, and the other of the mind or spirit.

It is significant that during Galileo’s lifetime, so swift was the movement, Descartes saw the trend of the new science and its inevitable effect on philosophy and religion. In his Système du Monde, he pictured a universe of matter and motion and nothing else,--a machine. From matter he tried to strip every sensible attribute except extension, or its mere geometrical position and extent. All phenomena became for him merely phases of motion. With the courage of his conviction, he even tried to imagine plants and animals to be mechanically acting automata. One thing only he could not include in this mechanism,--and that was thought and consciousness.

The cosmogony of Descartes has long since crumbled to dust, but the gap he made between the subjective and objective worlds has never been closed in spite of incessant later attempts. And these early creators of science, as something distinct from humanism, were quite conscious that they were engaged in a revolution which could end only with the overthrow of the dogmatic science of the Middle Ages, sheltered by the authority of Aristotle and the Bible. Galileo, Descartes, Pascal, and Bacon all declared explicitly that the old order must pass. From their day to ours, we have more and more regarded the universe as a machine, a combination of inert matter and moving forces, acting not as we may desire, but according to invariable laws which we have personified as Nature. Man was left, by the physicists, as a unique outsider who could interpret this machine in terms of his sensations and mind, but could neither alter nor avoid its fateful operation.

Only one step further was needed to identify all science with mechanics and to compress the scientific method within the limits imposed by mechanical laws. This fundamental principle was Newton’s discovery of the universal attraction of matter. According to this law, a single kind of force, depending only on the amount of matter and the distance between bodies, operated to hold the stars in their paths and to cause all the chemical and physical activities of atoms. With its discovery, the mechanistic theory was complete and dominant, and science had, in principle, gone as far as it can ever go. But, what is even more important, Newton grasped in his early years the fact that the scientific method is limited to the experimental investigation of objective phenomena, those which can be classified, measured geometrically, and formulated in laws which predict future events. He held with absolute consistency and restraint that what is once accomplished by this method is permanent. The experimental laws of gravitation, of the pressure of gases, and all others of like nature, are true within the limits of accuracy of our observation and measurement. If these improve, such laws do not fail, their mathematical expression is merely made more precise. They belong to the permanent acquisitions of the mind.

III

To attempt to explain the nature of matter, or heat, or light, the mechanism by which they act, or the method by which their energy is translated into sensation and thought, this, however, is to pass into the realm of metaphysics, or what Newton excellently called hypothesis. All such speculations are, at best, transitory, and, instead of predicting new lines of work, they lag behind the sure and steady advance of experimentation; they are constantly being revised to explain new phenomena after they are discovered. A convincing illustration of this criticism can be found in the history of the hypotheses of the nature of light. Physicists commonly assert that the corpuscular hypothesis retarded the advance of the subject of light for a century; their answer was to replace it by an equally metaphysical hypothesis of mechanical waves in an æther. After incessantly patching up this new conception during the next century, they are again returning to a corpuscular hypothesis, even more metaphysical and incomprehensible than its prototype. It seems impossible for us to learn that the trouble does not arise from the weakness of any particular variety, but lies in the nature of hypothesis, itself. We have created fictitious æthers, atoms, and electrons which bear no resemblance to sensible bodies; light is alternately a stream of corpuscles, or waves, or quanta of energy, or even a mathematical symbol; space is declared to be impenetrable except along certain curves; and time is confused with space. What one age proposes as a great advance is flung aside by the next which makes a new hypothesis whose only fate is to be rejected. So far have these speculations been carried that the dogma is seriously maintained that a false scientific hypothesis is valuable because in some mysterious way it leads to the discovery of truth.

As we have advanced in sober experimental science, these hypotheses have become more and more abstruse and more and more dogmatic until the most recent of these dreamers, Whitehead, Eddington, Einstein, have pictured a phantasmagoria, instead of a world, as non-sensical as the hallucinations of the mediæval monk driven mad by the fevers of asceticism.

Such models of the structure of matter may, indeed, be useful to give substance to our thought and a language for our ideas. They have something of the same sort of relation to real objects that portraits do to living persons. But there is this important point to be remembered. A skilful painter has seen and studied the person and can make so faithful a likeness as to create the illusion of reality. But the man of science is attempting to picture things which can never be seen, for atoms lie in the realm of the infinitely small, whose very existence is problematical. Models of atoms, of æthers, or of space have about the same degree of authenticity as the posthumous portrait of a person whom no one then alive had ever seen. Men of science are too prone to confuse the thing and the model in their own minds, and they have certainly been so careless in their teaching that even very highly educated laymen accept these hypotheses as facts. Is it not true that the world pretty generally takes the hypothetical explanation of gravitation by Einstein, which involves the concept of a fictitious space of more than three dimensions and the fusion of time with space, to be equally as scientific, and therefore equally as true, as the experimental law of the attraction of bodies? Do not many accept as a demonstrated fact one or another of the many hypotheses advanced by biologists to explain the cause of the observed variations in species? And having failed to distinguish between scientific fact and fiction, we have incorporated this mass of speculation into our philosophy of life and especially into our religion. We are worse confused than the Deists of the eighteenth century who believed that the mind of God could be defined by learning the facts and laws of Nature; we now propose that the intellectual and spiritual attributes of Man be framed in the hypotheses of dogmatic Science.

That the scientific method, as evolved from physics and chemistry, is not applicable to the problems of life has been the settled conviction of virtually all the investigators in those sciences. In fact, in order to achieve their results they have had to assume that life is a perturbation which cannot be included in a mechanical and mathematical world, and that so far as possible sense-perceptions must be excluded as criteria of laws. However, it has not been so clear to many of them that the mechanical method imposes definite, and rather narrow, limitations even upon the study of physical and chemical problems. These limitations were clearly defined in the seventeenth century during the protracted controversy between Newton on the one side, and Hooke and Huygens on the other, as to the nature of light and the modus operandi, or mechanism, of its transmission. The question involved was clear-cut; and it will pay to discuss it in some detail because it settled once for all, I think, the distinction between science and humanism.

Theoretical physics, from the very beginning, has been a synthesis of phenomena in terms of mechanics; that is, in terms of substance and motion. For example, the physical properties of heat, sound, and light are expressed by the same mathematical formulæ which express the motion of a wave in water. To distinguish between them, we assign different names to the substances involved, as a molecule of air, a corpuscle of light, or an æther. But whatever names we may give to them, or however we may try to distinguish them, we assign to all of them the common attribute of mass, or inertia, which is the only essential coefficient in a mechanical equation. And we use for all these different phenomena the same formula of motion, the quotient of the distance by the time. These quantities, mass and motion, when combined give us the law of mechanical energy, and our synthesis rests on the single fact that heat, sound, and light may be changed into mechanical motion, and may be produced by it. This energy is then their common and mutable factor.

But the objective phenomena of heat, light, and sound are cognisable to us through three separate sense-organs and are perceived as temperature, sight, and tone. These sensations are fundamentally different and, in fact, to confuse any of them with another is one of the surest indications of insanity. Thus the world as depicted by the physicist does not correspond with our world of sensation; nor does he attempt to do more than to discuss a restricted set of attributes, and not even those which really distinguish heat, light, etc., as such.

Newton, in his earliest published work, made evident this essential difference between the fields of physics and psychology. By means of a prism he refracted a beam of white sunlight into a continuous spectrum. He then placed a screen, containing a narrow slit, behind the prism in such a way as to permit only a very thin ray from the spectrum to pass on, and through, a second prism fastened parallel to the first prism. (I call it a homogeneous light ray to distinguish it from its psychological analogue, colour.) No matter what portion of the spectrum was used for the second prism, there was no further change of colour; the ray merely suffered a second angular deviation equal to that produced by the first refraction. He also recombined the whole spectrum by a reversed prism and obtained a single ray parallel to the original ray and pure white in colour. As a result of his experiments, he announced the following law: a primary ray of light is one which has a definite and specific angle of refraction by a prism, and each such primary ray is, to the eye, a primary colour. White is therefore a mixture of an indefinitely large number of primary rays, each possessing a different angle of deviation when passed through a prism; and when so separated each primary ray is seen by the eye as a primary colour.

The experiments of Newton were accepted as correct by Huygens and Hooke, probably the two most eminent physicists of the time. But they objected to his definition of a primary colour and to his conclusions. They had found previously, by their own experiments, that certain pairs of complementary colours, such as a certain red and a certain blue, gave to the eye the same sensation of white as did clear sunlight. They had defined them as the two primary colours which, by different proportions of mixture, would produce all other colours, including white. They therefore objected that it was unnecessary and cumbersome to assume an infinite number of primary rays when two were quite sufficient. By no process of reasoning could these two opinions be either reconciled or controverted. They involved fundamentally different criteria. White produced by the combination of a continuous spectrum and the white produced by a combination of red and blue were one and the same to Hooke and Huygens because their criterion of identity was the sensation of sight, and it must be the same for all psychologists who deal with subjective light. To Newton, the two whites were altogether different. The one examined by a prism gives a continuous spectrum, and the other gives two separated bands of blue and red. What, then, to the physicist is a fundamental dissimilarity is to the psychologist complete identity. How then can psychological sensations be studied by physical methods?

To show that this is not an isolated case, but that this gulf runs between the entire fields of physics and psychology, I can give an artificial example. While I deprecate the pseudo-scientific pictures, now fashionable, of the state of prehistoric man and of the condition of the earth before its habitability, I am able to imagine a world in which the eye had never developed, so that all life was blind. I am sure the word colour would never have been coined in such a world and that there could be no psychology of sight, but I also know that the blind race could develop a physical science of light because very many of its phenomena can be, and are now exclusively, studied by such apparatus as thermometers and electric galvanometers which can be read by touch. Or, to cite an everyday example, is not the mere fact, that the sensation produced by pepper on the tongue cannot be distinguished from that of heat, sufficient to make us hesitate before trying to study the sensations objectively, to synthesise the objective and subjective worlds, or to try to investigate them by the same method?