Part 10

Plato's conception of heaven and earth as two distinct regions is completed by his conception of the double nature of the soul; or, rather, of two souls, one rational and the other sensitive. The sensitive soul awakens the divine reminiscences of the rational soul; and the rational soul, by detecting the One in the Many, preserves man from the scepticism inevitably resulting from mere sense-knowledge.

Aristotle, who was born in 384 B.C., was Plato's pupil. He, however, completely broke away from his master's theory. He maintained that individual objects alone exist. But if only individual objects exist, only by the senses can they be known; and if we have only sense-knowledge, how can we arrive at the general truths on which both philosophy and science are founded? This was the problem which had led Plato to claim for ideas, or types of general truths, a higher origin than the intermittent and varying data of the senses.

Aristotle held that it could be solved in a natural way without the conception of an ideal world. In his view, ideas were obtained by induction. Sensation is the basis of all knowledge. But we have another faculty besides that of sensation; we have memory. Having perceived many objects, we remember our perceptions, and this enables us to discern wherein things differ and wherein they agree. Then, by means of the art of induction, we arrive at ideas. Aristotle's theory of induction is clearly explained by him: "Experience furnishes the principles of every science. Thus astronomy is grounded on observation. For if we were to observe properly the phenomena of the heavens, we might demonstrate the laws which regulate them. The same applies to other sciences." Had he always held before his eyes this conception of science, he would have anticipated Bacon--he would have been the Father of Positive Science. But he could not confine himself to experience, as there was not sufficient experience accumulated in his age from which to generalise with any effect. So he turned to logic as an instrument for investigating the mystery of existence, and by bringing physics and metaphysics together again, he paved the way for a new era--the era of scepticism.

All the wisdom of the ancient world was powerless against the sceptics. Faith in truth was extinct; faith in human nature was gone; philosophy was impossible. And, though the influence of Socrates continued to be felt in the field of ethics, the ethics of the Greeks were at best narrow and egotistical. What a light was poured upon all questions of morality by that one divine axiom, "Love your enemy." No Greek ever attained the sublimity of such a point of view. Still, the progress made by the Greeks was immense, and they must ever occupy in the history of humanity an honourable place.

III.--Philosophy and Science

Francis Bacon is the father of experimental philosophy. He owes his title to his method. Many philosophers, ancient and modern, had cursorily referred to observation and experiment as furnishing the materials of physical knowledge; but no one before him had attempted to systematise the true method of discovery.

He begins his great work by examining into the permanent causes of error, as these were likely to be operative even after the reformation of science. For this reason he calls them idols, or false appearances (from the Greek, eidolon), and he divides them into four classes: the idols of the tribe, or the causes of error due to the general defects of the human mind; the idols of the den, which spring from weaknesses peculiar to the character of the individual student; the idols of the forum, which arise out of the intercourse of society and the power that words sometimes have of governing thought; and, finally, the idols of the theatre, which men of great learning pursue when they follow the systems of famous but mistaken thinkers.

After this preliminary discussion, Bacon goes on to describe the methods of inductive science. The first step consists in preparing a history of the phenomena to be explained in all their modifications and varieties. This history must include not merely such facts as spontaneously offer themselves, but all experiments instituted for the sake of discovery. It must be composed with great care; the facts should be accurately related and distinctly arranged, and their authenticity diligently examined; those that rest on doubtful evidence should not be rejected, but noted as uncertain, with the grounds of the judgment so formed. This last part of the method, says Bacon, is very necessary, for facts often appear incredible only because we are ill-informed, and they cease to seem marvellous when our knowledge is further extended.

When this record of facts, this "natural history," is completed, an attempt may then be made to discover, by a comparison of the various facts, the cause of the phenomena. Here it is of the utmost importance to bear in mind that all facts have not the same value. There are, as Bacon points out, twenty-seven species of facts, and he concludes that in any science where facts cannot be tested by experiment there can be no conclusive evidence.

Thus it will be seen that Bacon's method was a system of specific rules. He did not merely tell men to make observations and experiments; he taught them how observations and experiments ought to be made.

As Bacon was the father of modern science, so Réne Descartes was the father of modern philosophy. Born in 1596, and perplexed by the movement of scepticism produced by the Renaissance, the French thinker endeavoured to find some ground of certainty in the fact that he at least knew of his own existence. Hence his famous saying: Cogito, ergo sum--"I think, therefore I exist." Consciousness, said he, is the basis of all knowledge. The process then is simple: examine your consciousness, and its clear replies will be science. Hence the vital portion of his system lies in this axiom: "All clear ideas are true."

The fallacy in his system can be briefly exposed. Consciousness is, no doubt, the ultimate ground of certainty of existence for me. But though I am conscious of all that passes within myself, I am not conscious of what passes in anything not myself. All that I can possibly know of anything not myself lies in its effects upon me. Any other ideas I may have in regard to the outside world are founded only on inferences, and directly I leave the ground of consciousness for the region of inference my knowledge becomes questionable.

It was this defect in Cartesianism which Baruch Spinoza, the great Jewish thinker of Amsterdam, set out to rectify. Spinoza asked himself: What was the reality which lies beneath all appearance? We see everywhere transformations perishable and perishing, yet there must be something beneath which is imperishable and immutable. What is it? In Spinoza's view, the absolute existence is God. All that exists, exists in and by God. Taking the words of St. Paul, "In Him we live and move and have our being," as his motto, he undertook to trace the relations of the world to God and to man, and those of man to society.

To John Locke, born at Wrington, in Somerset, in 1632, the problem presented itself in another way. Instead of accepting the validity of clear ideas, as Descartes and Spinoza did, he adopted the Baconian method, and opened the inquiry into the origin and formation of ideas. Separating himself from the philosophers who held that the mind was capable of arriving at knowledge independent of experience, and from the sceptics who maintained that the senses were the only channels of information, he showed that ideas were derived from two sources--sensation and reflection.

He was succeeded by George Berkeley, Bishop of Cloyne, born at Kilcrin in Kilkenny, in 1684. He defeated the sceptics on their own ground. There is nothing in the world, he says, except our own sensations and ideas. In order to exist for us, things have to be perceived by the mind; therefore, everything, in order to exist, must exist in the mind of God. But when Berkeley had proved that matter was figment, David Hume, born in 1711, came forward and showed that mind was also an illusion. You know nothing of matter, said Berkeley; you have only perceptions and the ideas based thereon. You know nothing of mind, replied Hume; you have only a succession of sensations and ideas.

Against Hume rose up in Germany a famous school of philosophers beginning with Immanuel Kant, who was born in Prussia in 1724. Kant attempted to prove that the human reason was not untrustworthy, as Hume assumed, but limited, and that, within certain bounds, it was capable of arriving at practical truths. Kant's disciples, however, were not content with this modest restatement. Taking it too readily for granted that Hume's objections had been overcome, they proceeded to revive that unbounded faith in mere speculation which had been the distemper of the Greek mind. Fichte and Schelling were the first thinkers of note to attempt again to solve by logic the mystery of the universe.

But their works are now obscured by the achievement of Hegel, who began to teach at Berlin in 1818. Hegel holds that the real universe is a universe of ideas to which his philosophy is the key, but, as ideas realise themselves in space and time, they come within the scope of the man of science. It is said that all bad German systems of philosophy when they die come to England. Hegelianism has certainly been very fashionable in this country, and its influence is still observable in academic circles.

Auguste Comte is the Bacon of the nineteenth century. It has been his object to construct a positive philosophy; that is to say, a doctrine capable of embracing all the sciences, and, with them, all the problems of social life. He holds that every branch of knowledge passes through three stages: the supernatural, or fictitious; the metaphysical or abstract; the positive or scientific. When the positive method is adopted, then shall we again have one general doctrine, powerful because general.

The metaphysicians have failed to penetrate to the causes of things, but the men of science are succeeding in the humbler but far more useful work of tracing some of the laws that govern the phenomena of nature, and foreseeing their operations. It is only where the philosophers started matters capable of positive treatment that any advance has been made in metaphysics. For the rest, philosophy leaves us in the nineteenth century at precisely the same point at which we were in the fifth. Thus is the circle completed.

JOHN LOCKE

Concerning the Human Understanding

John Locke was born at Wrington, Somersetshire, England, Aug. 29, 1632. He was educated at Westminster and at Christ Church, Oxford; but his temperament rebelled against the system of education still in vogue and the public disputations of the schools, which he thought "invented for wrangling and ostentation rather than to discover truth." It was his study of Descartes that first "gave him a relish of philosophical things." From 1683 to 1689 he found it prudent to sojourn in Holland. In the latter year he returned to England, bringing with him the manuscript of the "Essay Concerning Human Understanding," which appeared in the spring of 1690. Few works of philosophy have made their way more rapidly than the "Essay." Twenty editions appeared before 1700. The design of the book, Locke explains in the introduction, is to inquire "into the origin, certainty, and extent of human knowledge, together with the grounds and degrees of belief, opinion, and assent." Locke died on October 28, 1704.

I.--The Nature of Simple Ideas

"Idea" being that term which, I think, serves best to stand for whatsoever is the object of the understanding. I have used it to express whatever is meant by phantasm, notion, species, or whatever it is the mind can be employed about in thinking. Let us, then, suppose the mind to be, as we say, white paper void of all characters--without any ideas. Whence comes it by that vast store which the busy and boundless fancy of man has painted on it with an almost endless variety? To this, I answer in one word--Experience; in that all our knowledge is founded, and from that it ultimately derives itself.

Let anyone examine his own thoughts and thoroughly search his understanding, and then let him tell me whether of all the original ideas he has there are any other than of the objects of his senses, or of the observations of his mind considered as objects of his reflection. Though the qualities that affect our senses are, in the things themselves, so united and blended that there is no separation, no distance between them, yet it is plain the ideas they produce in the mind enter by the senses simple and unmixed. For, though the sight and touch often take in from the same object at the same time different ideas, yet the simple ideas thus united in the same subject are as perfectly distinct as those that come in by different senses; the coldness and hardness which a man feels in a piece of ice being as distinct ideas in the mind as the smell and whiteness of a lily, and each of them being in itself uncompounded, contains nothing but one uniform appearance, or conception, in the mind, and is not distinguishable into different ideas.

When the understanding is once stored with these simple ideas, it has the power to repeat, compare, and unite them even to an almost infinite variety, and so can make at will new complex ideas. But it is not in the power of any most exalted wit or enlarged understanding, by any quickness or variety of thought, to invent or frame one new simple idea in the mind, nor to destroy those that are there. I would have anyone try to fancy any taste which had never affected his palate, or frame the idea of a scent he had never smelt; and when he can do this, I will also conclude that a blind man hath ideas of colours and a deaf man true, distinct notions of sound.

There are some ideas which have admittance only through one sense which is peculiarly adapted to receive them. Thus, light and colours come in only by the eye, all kinds of noises by the ear, the tastes and smells by the nose and palate. The most considerable of those belonging to the touch are heat, cold, and solidity--which is the idea that belongs to the body, whereby we conceive it to fill space.

Simple ideas of divers senses are the ideas of space or extension, figure, rest, and motion, for these make perceivable impressions both on the eyes and touch, and we can receive and convey into our minds the ideas of the extension, figure, motion, and rest of bodies both by seeing and feeling.