A History of Western Philosophy

by Bertrand Russell

  The first thing to note is the removal of almost all traces of animism from the laws of physics. The Greeks, though they did not say so explicitly, evidently considered the power of movement a sign of life. To common-sense observation it seems that animals move themselves, while dead matter only moves when impelled by an external force. The soul of an animal, in Aristotle, has various functions, and one of them is to move the animal’s body. The sun and planets, in Greek thinking, are apt to be gods, or at least regulated and moved by gods. Anaxagoras thought otherwise, but was impious. Democritus thought otherwise, but was neglected, except by the Epicureans, in favour of Plato and Aristotle. Aristotle’s forty-seven or fifty-five unmoved movers are divine spirits, and are the ultimate source of all the motion in the universe. Left to itself, any inanimate body would soon become motionless; thus the operation of soul on matter has to be continuous if motion is not to cease.

  All this was changed by the first law of motion. Lifeless matter, once set moving, will continue to move for ever unless stopped by some external cause. Moreover the external causes of change of motion turned out to be themselves material, whenever they could be definitely ascertained. The solar system, at any rate, was kept going by its own momentum and its own laws; no outside interference was needed. There might still seem to be need of God to set the mechanism working; the planets, according to Newton, were originally hurled by the hand of God. But when He had done this, and decreed the law of gravitation, everything went on by itself without further need of divine intervention. When Laplace suggested that the same forces which are now operative might have caused the planets to grow out of the sun, God’s share in the course of nature was pushed still further back. He might remain as Creator, but even that was doubtful, since it- was not clear that the world had a beginning in time. Although most of the men of science were models of piety, the outlook suggested by their work was disturbing to orthodoxy, and the theologians were quite justified in feeling uneasy.

  Another thing that resulted from science was a profound change in the conception of man’s place in the universe. In the medieval world, the earth was the centre of the heavens, and everything had a purpose concerned with man. In the Newtonian world, the earth was a minor planet of a not specially distinguished star; astronomical distances were so vast that the earth, in comparison, was a mere pin-point. It seemed unlikely that this immense apparatus was all designed for the good of certain small creatures on this pin-point. Moreover purpose, which had since Aristotle formed an intimate part of the conception of science, was now thrust out of scientific procedure. Any one might still believe that the heavens exist to declare the glory of God, but no one could let this belief intervene in an astronomical calculation. The world might have a purpose, but purposes could no longer enter into scientific explanations.

  The Copernican theory should have been humbling to human pride, but in fact the contrary effect was produced, for the triumphs of science revived human pride. The dying ancient world had been obsessed with a sense of sin, and had bequeathed this as an oppression to the Middle Ages. To be humble before God was both right and prudent, for God would punish pride. Pestilences, floods, earthquakes, Turks, Tartars, and comets perplexed the gloomy centuries, and it was felt that only greater and greater humility would avert these real or threatened calamities. But it became impossible to remain humble when men were achieving such triumphs:

  Nature and Nature’s laws lay hid in night.

  God said “Let Newton be,” and all was light.

  And as for damnation, surely the Creator of so vast a universe had something better to think about than sending men to hell for minute theological errors. Judas Iscariot might be damned, but not Newton, though he were an Arian.

  There were of course many other reasons for self-satisfaction. The Tartars had been confined to Asia, and the Turks were ceasing to be a menace. Comets had been humbled by Halley, and as for earthquakes, though they were still formidable, they were so interesting that men of science could hardly regret them. Western Europeans were growing rapidly richer, and were becoming lords of all the world: they had conquered North and South America, they were powerful in Africa and India, respected in China and feared in Japan. When to all this were added the triumphs of science, it is no wonder that the men of the seventeenth century felt themselves to be fine fellows, not the miserable sinners that they still proclaimed themselves on Sundays.

  There are some respects in which the concepts of modern theoretical physics differ from those of the Newtonian system. To begin with, the conception of “force,” which is prominent in the seventeenth century, has been found to be superfluous. “Force,” in Newton, is the cause of change of motion, whether in magnitude or direction. The notion of cause is regarded as important, and force is conceived imaginatively as the sort of thing that we experience when we push or pull. For this reason it was considered an objection to gravitation that it acted at a distance, and Newton himself conceded that there must be some medium by which it was transmitted. Gradually it was found that all the equations could be written down without bringing in forces. What was observable was a certain relation between acceleration and configuration; to say that this relation was brought about by the intermediacy of “force” was to add nothing to our knowledge. Observation shows that planets have at all times an acceleration towards the sun, which varies inversely as the square of their distance from it. To say that this is due to the “force” of gravitation is merely verbal, like saying that opium makes people sleep because it has a dormitive virtue. The modern physicist, therefore, merely states formulae which determine accelerations, and avoids the word “force” altogether. “Force” was the faint ghost of the vitalist view as to the causes of motions, and gradually the ghost has been exorcized.

  Until the coming of quantum mechanics, nothing happened to modify in any degree what is the essential purport of the first two laws of motion, namely this: that the laws of dynamics are to be stated in terms of accelerations. In this respect, Copernicus and Kepler are still to be classed with the ancients; they sought laws stating the shapes of the orbits of the heavenly bodies. Newton made it clear that laws stated in this form could never be more than approximate. The planets do not move in exact ellipses, because of the perturbations caused by the attractions of other planets. Nor is the orbit of a planet ever exactly repeated, for the same reason. But the law of gravitation, which deals with accelerations, was very simple, and was thought to be quite exact until two hundred years after Newton’s time. When it was emended by Einstein, it still remained a law dealing with accelerations.

  It is true that the conservation of energy is a law dealing with velocities, not accelerations. But in calculations which use this law it is still accelerations that have to be employed.

  As for the changes introduced by quantum mechanics, they are very profound, but still, to some degree, a matter of controversy and uncertainty.

  There is one change from the Newtonian philosophy which must be mentioned now, and that is the abandonment of absolute space and time. The reader will remember a mention of this question in connection with Democritus. Newton believed in a space composed of points, and a time composed of instants, which had an existence independent of the bodies and events that occupied them. As regards space, he had an empirical argument to support his view, namely that physical phenomena enable us to distinguish absolute rotation. If the water in a bucket is rotated, it climbs up the sides and is depressed in the centre; but if the bucket is rotated while the water is not, there is no such effect. Since his day, the experiment of Foucault’s pendulum has been devised, giving what has been considered a demonstration of the earth’s rotation. Even on the most modern views, the question of absolute rotation presents difficulties. If all motion is relative, the difference between the hypothesis that the earth rotates and the hypothesis that the heavens revolve is purely verbal; it is no more than the difference between “John is the father of James” and “James is the son of John.” But
if the heavens revolve, the stars move faster than light, which is considered impossible. It cannot be said that the modern answers to this difficulty are completely satisfying, but they are sufficiently satisfying to cause almost all physicists to accept the view that motion and space are purely relative. This, combined with the amalgamation of space and time into space-time, has considerably altered our view of the universe from that which resulted from the work of Galileo and Newton. But of this, as of quantum theory, I will say no more at this time.

  CHAPTER VII

  Francis Bacon

  FRANCIS BACON (1561-1626), although his philosophy is in many ways unsatisfactory, has permanent importance as the founder of modern inductive method and the pioneer in the attempt at logical systematization of scientic procedure.

  He was a son of Sir Nicholas Bacon, Lord Keeper of the Great Seal, and his aunt was the wife of Sir William Cecil, afterwards Lord Burghley; he thus grew up in the atmosphere of state affairs. He entered Parliament at the age of twenty-three, and became adviser to Essex. None the less, when Essex fell from favour he helped in his prosecution. For this he has been severely blamed: Lytton Strachey, for example, in his Elizabeth and Essex, represents Bacon as a monster of treachery and ingratitude. This is quite unjust. He worked with Essex while Essex was loyal, but abandoned him when continued loyalty to him would have been treasonable; in this there was nothing that even the most rigid moralist of the age could condemn.

  In spite of his abandonment of Essex, he was never completely in favour during the lifetime of Queen Elizabeth. With James’s accession, however, his prospects improved. In 1617 he acquired his father’s office of Keeper of the Great Seal, and in 1618 he became Lord Chancellor. But after he had held this great position for only two years, he was prosecuted for accepting bribes from litigants. He admitted the truth of accusation, pleading only that presents never influenced his decision. As to that, any one may form his own opinion, since there can be no evidence as to the decisions that Bacon would have come to in other circumstances. He was condemned to a fine of £40,000, to imprisonment in the Tower during the king’s pleasure, to perpetual banishment from court and inability to hold office. This sentence was only very partially executed. He was not forced to pay the fine, and he was kept in the Tower for only four days. But he was compelled to abandon public life, and to spend the remainder of his days in writing important books.

  The ethics of the legal profession, in those days, were somewhat lax. Almost every judge accepted presents, usually from both sides. Nowadays we think it atrocious for a judge to take bribes, but even more atrocious, after taking them, to decide against the givers of them. In those days, presents were a matter of course, and a judge showed his “virtue” by not being influenced by them. Bacon was condemned as an incident in a party squabble, not because he was exceptionally guilty. He was not a man of outstanding moral eminence, like his forerunner Sir Thomas More, but he was also not exceptionally wicked. Morally, he was an average man, no better and no worse than the bulk of his contemporaries.

  After five years spent in retirement, he died of a chill caught while experimenting on refrigeration by stuffing a chicken full of snow.

  Bacon’s most important book, The Advancement of Learning, is in many ways remarkably modern. He is commonly regarded as the originator of the saying “Knowledge is power,” and though he may have had predecessors who said the same thing, he said it with new emphasis. The whole basis of his philosophy was practical: to give mankind mastery over the forces of nature by means of scientific discoveries and inventions. He held that philosophy should be kept separate from theology, not intimately blended with it as in scholasticism. He accepted orthodox religion; he was not the man to quarrel with the government on such a matter. But while he thought that reason could show the existence of God, he regarded everything else in theology as known only by revelation. Indeed he held that the triumph of faith is greatest when to the unaided reason a dogma appears most absurd. Philosophy, however, should depend only upon reason. He was thus an advocate of the doctrine of “double truth,” that of reason and that of revelation. This doctrine had been preached by certain Averroists in the thirteenth century, but had been condemned by the Church. The “triumph of faith” was, for the orthodox, a dangerous device. Bayle, in the late seventeenth century, made ironical use of it, setting forth at great length all that reason could say against some orthodox belief, and then concluding “so much the greater is the triumph of faith in nevertheless believing.” How far Bacon’s orthodoxy was sincere it is impossible to know.

  Bacon was the first of the long line of scientifically minded philosophers who have emphasized the importance of induction as opposed to deduction. Like most of his successors, he tried to find some better kind of induction than what is called “induction by simple enumeration.” Induction by simple enumeration may be illustrated by a parable. There was once upon a time a census officer who had to record the names of all householders in a certain Welsh village. The first that he questioned was called William Williams; so were the second, third, fourth, … At last he said to himself: “This is tedious; evidently they are all called William Williams. I shall put them down so and take a holiday.” But he was wrong; there was just one whose name was John Jones. This shows that we may go astray if we trust too implicitly in induction by simple enumeration.

  Bacon believed that he had a method by which induction could be made something better than this. He wished, for example, to discover the nature of heat, which he supposed (rightly) to consist of rapid irregular motions of the small parts of bodies. His method was to make lists of hot bodies, lists of cold bodies, and lists of bodies of varying degrees of heat. He hoped that these lists would show some characteristic always present in hot bodies and absent in cold bodies, and present in varying degrees in bodies of different degress of heat. By this method he expected to arrive at general laws, having, in the first instance, the lowest degree of generality. From a number of such laws he hoped to reach laws of the second degree of generality, and so on. A suggested law should be tested by being applied in new circumstances; if it worked in these circumstances it was to that extent confirmed. Some instances are specially valuable because they enable us to decide between two theories, each possible so far as previous observations are concerned; such instances are called “prerogative” instances.

  Bacon not only despised the syllogism, but undervalued mathematics, presumably as insufficiently experimental. He was virulently hostile to Aristotle, but thought very highly of Democritus. Although he did not deny that the course of nature exemplifies a Divine purpose, he objected to any admixture of teleological explanation in the actual investigation of phenomena; everything, he held, should be explained as following necessarily from efficient causes.

  He valued his method as showing how to arrange the observational data upon which science must be based. We ought, he says, to be neither like spiders, which spin things out of their own insides, nor like ants, which merely collect, but like bees, which both collect and arrange. This is somewhat unfair to the ants, but it illustrates Bacon’s meaning.

  One of the most famous parts of Bacon’s philosophy is his enumeration of what he calls “idols,” by which he means bad habits of mind that cause people to fall into error. Of these he enumerates five kinds. “Idols of the tribe” are those that are inherent in human nature; he mentions in particular the habit of expecting more order in natural phenomena than is actually to be found. “Idols of the cave” are personal prejudices, characteristic of the particular investigator. “Idols of the market-place” are those that have to do with the tyranny of words and the difficulty of escaping from their influence over our minds. “Idols of the theatre” are those that have to do with received systems of thought; of these, naturally Aristotle and the scholastics afforded him the most noteworthy instances. Lastly there are “idols of the schools,” which consist in thinking that some blind rule (such as the syllogism) can take the place of judgement in inv
estigation.

  Although science was what interested Bacon, and although his general outlook was scientific, he missed most of what was being done in science in his day. He rejected the Copernican theory, which was excusable so far as Copernicus himself was concerned, since he did not advance any very solid arguments. But Bacon ought to have been convinced by Kepler, whose New Astronomy appeared in 1609. Bacon appears not to have known of the work of Vesalius, the pioneer of modern anatomy, or of Gilbert, whose work on magnetism brilliantly illustrated inductive method. Still more surprising, he seemed unconscious of the work of Harvey, although Harvey was his medical attendant. It is true that Harvey did not publish his discovery of the circulation of the blood until after Bacon’s death, but one would have supposed that Bacon would have been aware of his researches. Harvey had no very high opinion of him, saying “he writes philosophy like a Lord Chancellor.” No doubt Bacon could have done better if he had been less concerned with worldly success.

  Bacon’s inductive method is faulty through insufficient emphasis on hypothesis. He hoped that mere orderly arrangement of data would make the right hypothesis obvious, but this is seldom the case. As a rule, the framing of hypotheses is the most difficult part of scientific work, and the part where great ability is indispensable. So far, no method has been found which would make it possible to invent hypotheses by rule. Usually some hypothesis is a necessary preliminary to the collection of facts, since the selection of facts demands some way of determining relevance. Without something of this kind, the mere multiplicity of facts is baffling.

  The part played by deduction in science is greater than Bacon supposed. Often, when a hypothesis has to be tested, there is a long deductive journey from the hypothesis to some consequence that can be tested by observation. Usually the deduction is mathematical, and in this respect Bacon underestimated the importance of mathematics in scientific investigation.