CHAPTER III

GROWTH OF THE MECHANICAL THEORY

DECLINE OF SCHOLASTICISM.--By the time of Lord Bacon, the Scholastic philosophy might have been described as extinct; it no longer survived as a living system. The loss was a serious one to mankind, which was poorer by the discrediting of an authoritative body of thought, a possession it seems ill able to dispense with. The Baconian philosophy was an imperfect substitute; it was little more than a system of enquiry, a manual of scientific procedure, for Bacon himself was not in the philosophical sense a profound or constructive thinker, though he was one of those men of talent who can give utterance to the tendencies of an epoch.

THE NEW PHILOSOPHY.--The task, however, of constructing a new philosophy of the universe was courageously taken in hand by a succession of thinkers, and the energy of thought which the great problem generated is characteristic of perhaps the most vigorous century of European history--the seventeenth.

The tendency of the new discoveries in science had not been obscure, and Modern Philosophy starts with an attempt to represent the universe as a self-working machine--a co-ordinated whole, throughout which the principles of mathematics are universally valid. The trend of ideas set in motion by the new discoveries in astronomy seemed to point in this direction. But to introduce mechanics into the celestial regions, though an important step, was but a beginning. Mechanics must be _universally_ valid--even in the human body--or the new teaching was vain. Exceptions may prove a rule, but they destroy a philosophy.

THE SUBJUGATION OF PHYSIOLOGY.--It was an Englishman who provided the necessary facts to fill the gravest gap in the mechanical theory. It was already known in the previous century that the blood of animals circulated throughout the body; the existence and use of veins and heart-valves was also known, but it was William Harvey (1578-1657) who discovered the heart to be the organ responsible for _maintaining_ the circulation of the blood, by purely mechanical means. This was a fact of the utmost significance. In the sphere of physiology, where theories about mysterious powers of blood or soul had been hitherto authoritative, it effected a revolution. Indeed it is true to say that Harvey "is to physiology what Galileo was to physics." He proved that "the general laws of motion are valid within as well as without the organism"--an important extension of the mechanical theory.

DESCARTES.--Among the leading men who accepted Harvey's theory, one of the first was Rene Descartes (1596-1650). Well might this thinker welcome it, for it was a most important contribution to the imposing philosophic fabric for which he was industriously collecting materials. Descartes, apart from his philosophical speculations, is an interesting character, being a Frenchman of noble birth who was educated by the Jesuits, saw something of contemporary life in Paris, served as a military officer in Holland and Germany, and made some original discoveries in mathematics.

The mathematical mind, accustomed as it is to deal with highly abstract ideas, takes kindly to metaphysics. And it very often solves the mystery of the universe by expressing all its contents in mathematical terms. Such, at least, was Descartes' method. The simplest and clearest ideas which we can have of anything are mathematical, i.e. extension and mobility. And it is by concentrating our attention upon this simple and mathematical aspect of things that we shall arrive at a proper understanding of all that goes on in the material world.

UNIVERSALITY OF MATHEMATICS.--A phenomenon was, in Descartes' eyes, "explained" only when a "cause" which is its exact _mathematical equivalent_, has been indicated. The "cause" and the "effect" are two sides of a mathematical equation (_Causa aequat effectum_). Anything that happens in the material world (the fall of a stone, the beat of a heart, the rising of the sun) is really nothing more than a redistribution of portions of that sum of motion which, once generated at the Creation, has remained unaltered, and unalterable, in the universe ever since. The sum of motion is constant, there can be no addition to or subtraction from it. In this sense it would be true that "there is nothing new under the sun": only ever-new distributions of the old.

THE UNIVERSE A MACHINE.--Once assume that all phenomena can be interpreted in terms of motion, and add the proposition (already enunciated by Galileo) that motion once set going will proceed for ever, unless some impediment from outside intervenes, and the mechanical view of the universe is complete. The universe is a machine, i.e. a thing that works (1) according to mathematical principles, (2) automatically.

ELABORATIONS OF THE MECHANICAL THEORY.--The importance of Descartes lies not in his having invented this conception (we have already seen it in the hands of Leonardo da Vinci, Galileo, and others), but in his having elaborated it. This he did in two directions: (1) he attempted to supply a mechanical theory of the evolution of the world-system; _i.e._ to show how the heavenly bodies came into being by natural and mechanical processes; (2) he applied the mechanical theory to organisms; animals and men were complex machines. (Here, as we have seen, the discovery of Harvey was of prime importance.)

It is hardly necessary to describe at length Descartes' mechanical theory of the evolution of the world-system, though an interest attaches to it as being the ancestor of the modern "nebular hypothesis." Matter in whirling motion around fixed centres is the original _datum_ from which Descartes evokes the universe. With regard to the mechanical theory of organisms, Descartes developed it at some length in various treatises. All the functions and actions of animals were regarded by him as entirely involuntary and mechanical. "That the lamb flees at the sight of a wolf happens because the rays of light from the body of the wolf strike the eye of the lamb, and set the muscles in motion by means of the 'reflex' currents of the animal spirits."

In the case of human beings, owing to the phenomenon of "consciousness," Descartes felt compelled to assume a "soul"--a _thinking_ substance in reciprocal action with the _material_ substance (of the brain). This, too, is an anticipation of the modern theory of "psycho-physical parallelism."

CARTESIANISM.--The ideas of Descartes had considerable influence among his contemporaries, and Cartesianism, as it was called, became fashionable in intellectual circles. It developed a tendency towards free enquiry and independent thought; and it was even more significant as an atmosphere than as a system of ideas. Though in this respect too, it was both important and vital; as we have observed, modern mechanical theories find their parent in Descartes.

Nor was it only, we may remark, among philosophers and men of science that Cartesian ideas were popular; they were accepted and elaborated by the religious thinkers who hoped to harmonise and humanise theology and science. Pascal, Bossuet and Fenelon, the finest minds in the French Church, were eager Cartesians.[5]

This aspect of the matter, i.e. the significance of Cartesianism for religion, we can for the present postpone.

RESULTS SO FAR.--Successive breaches in the Scholastic system have now been noted. Copernicus had introduced a new astronomy, Galileo a new physics, Descartes (with the help of Harvey) a new physiology, and the beginnings of a new psychology.

CONTRIBUTIONS OF HOBBES.--The step that remained was taken by an Englishman, Thomas Hobbes (1588-1679), who attempted to provide a system of ethics and a theory of politics upon a purely naturalistic basis. Hobbes was a particularly energetic thinker. He worked out a psychology of the feelings, which reduced everything to the impulse of self-preservation and the instinct for power. Men were induced by these instincts to agree to certain rules of conduct, for the sake of expediency. Social life seems essential if men are to live together--the instinct of self-preservation demands it--and social life in turn demands certain renunciations: thus fidelity, gratitude, forbearance, justice, etc., must be practised.

Thus Hobbes attempted to banish all mysterious or obscure forces from morality, which was the characteristic and inevitable product of human nature and human circumstances. This way of looking at things seemed strange to all, and even revolting to some, of Hobbes' contemporaries. As the mystical powers of motion which the Scholastics had believed in were banished by the new physics and the new physiology, so the new psychology could allow of no mystical faculty which can decide in all problems of good and evil.

With Hobbes, then, a naturalistic view of the universe may be said to have been tolerably complete: it embraces physics, psychology, and ethics. There still remained, of course, a number of gaps in scientific knowledge, and consequently any philosophy based thereupon could not yet be regarded as secure. These gaps, however, as research proceeded and successive discoveries were made, tended to diminish both in size and quantity.

NEWTON.--The seventeenth and the early eighteenth centuries were fruitful in revelations of this kind, and natural knowledge steadily and even rapidly progressed. And one thinker, who may be regarded as a link between the seventeenth century and that which succeeded it, may now claim our attention.

The name of Newton (1642-1727) is as familiar to Englishmen as that of Shakespeare, and the discovery by him of the "law of gravitation" is one of those scraps of information which we acquire, and perhaps fail to understand, in early childhood.

Newton's scientific method is a no less important aspect of his work than its results. The _Principia_, in which he gave his discovery to the world, is "a model for all scientific investigations which has never been surpassed." It was, indeed, a brilliant application of the principle of inferring the unknown from the already known, without any dogmatic leaps in the dark. The principle with which he began was that what is true in the narrower spheres of experience (e.g. in the case of an apple falling) is true also in the wider spheres (e.g. in the movements of the celestial bodies). He then made a careful mathematical deduction of what would happen in the case of the planets, assuming that the laws of falling bodies on the earth were applicable to them also. And he concluded by showing that what would happen according to mathematics under this assumption _actually does happen_. The conclusion follows that the same force, i.e. "attraction," operates in both cases. It is no wonder that this final and successful operation was performed by Newton "in a state of excitement so great that he could hardly see his figures."

SIGNIFICANCE OF HIS DISCOVERY.--The philosophic importance of the discovery that the motions of the planets may be explained by the "law of gravitation" was twofold. In the first place, it now became possible to understand how the universe held together (a problem which the new astronomy had not solved); and in the second place, the theory constituted a large extension of the mechanical view. It demonstrated that "the physical laws which hold good on the surface of the earth are valid throughout the universe, so far as we can know anything of it." Thus the area of existence in which physical law held good was at once infinitely widened. The mechanical theories of Galileo, Descartes, and others, not only received confirmation, but became more comprehensive than before.

So that Newton may be said to have put the finishing touch upon the achievements of his predecessors, and to have crowned their labours with success. And his work has the characteristic of permanency: his "gravitation formula" has stood the test of time. "It still stands there," says a careful and authoritative writer, "as almost the only firmly established mathematical relation, expressive of a property of all matter, to which the progress of more than two centuries has added nothing, and from which it has taken nothing away."[6]

RELIGIOUS COROLLARIES.--It would be a profound mistake to assume that the creators of the mechanical view, as it has hitherto met us, were animated by any hostility to religion. Nor did they believe their theories to involve any disastrous consequences in that sphere.

The new astronomy of Copernicus had actually been made the basis of a spiritual view of the universe by the profound genius (both philosophical and religious) of Giordano Bruno. And the fact that the ecclesiastical authorities rejected his view need not divest it of importance or of value in our eyes. Bruno's own faith was not disturbed by the infidelity of his persecutors. "Ye who pass judgment upon me feel, maybe, greater fear than I upon whom it is passed," were his last words to them. Had they _believed_, they need not have been afraid, and might have been content with the policy of Gamaliel.

As for Descartes and Hobbes, their notions were no doubt distasteful to conservative minds (the Jesuits were no friends to either), but Descartes regarded himself, and would fain have been regarded by others, as a good Catholic; and Hobbes, theologically, was what in these days we might call a Liberal Protestant. Cartesianism, as we have seen, came to be a name for a type of thought which studied to harmonise science and theology, and one of the most profound religious geniuses of any age--Pascal, was (as we have seen) a Cartesian.

As for Newton, his view of the universe was essentially a religious one, though he did not allow theological speculations to intrude upon his strictly scientific work. His attitude is indicated by a reply to the inquiry of a contemporary theologian as to how the movements and structure of the solar system were to be accounted for.

"To your query I answer that the motions which the planets now have could not spring from any natural cause alone.... To compare and adjust all these things together (i.e. quantities of matter and gravitating powers, etc.) in so great a variety of bodies, argues the cause to be not blind and fortuitous, but very well skilled in mechanism and geometry."[7]

Still, the mechanical view contained within it sinister possibilities; and the instincts of conservative thinkers were not altogether at fault. The mechanical view in itself need not be hostile to a spiritual and rational religion (though it is fatal to most forms of superstition); and yet that view can be used in the interests of anti-religious prejudice--and, as we shall see, it was so used, and with considerable effect.

Meanwhile, however, we shall pass on to consider the work of three thinkers who are typical of a revolt from what was in danger of becoming the all-absorbing tyranny of mechanics. This reaction (for so it may be termed) we shall proceed, in the following chapter, to examine.

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