An Introduction to Philosophy Part 15

IV. SOME TYPES OF PHILOSOPHICAL THEORY

CHAPTER XII

THEIR HISTORICAL BACKGROUND

48. THE DOCTRINE OF REPRESENTATIVE PERCEPTION.--We have seen in Chapter II that it seems to the plain man abundantly evident that he really is surrounded by material things and that he directly perceives such things. This has always been the opinion of the plain man and it seems probable that it always will be. It is only when he begins to reflect upon things and upon his knowledge of them that it occurs to him to call it in question.

Very early in the history of speculative thought it occurred to men, however, to ask how it is that we know things, and whether we are sure we do know them. The problems of reflection started into life, and various solutions were suggested. To tell over the whole list would take us far afield, and we need not, for the purpose we have in view, go back farther than Descartes, with whom philosophy took a relatively new start, and may be said to have become, in spirit and method, at least, modern.

I have said (section 31) that Descartes (1596-1650) was fairly well acquainted with the functioning of the nervous system, and has much to say of the messages which pa.s.s along the nerves to the brain. The same sort of reasoning that leads the modern psychologist to maintain that we know only so much of the external world as is reflected in our sensations led him to maintain that the mind is directly aware of the ideas through which an external world is represented, but can know the world itself only indirectly and through these ideas.

Descartes was put to sore straits to prove the existence of an external world, when he had once thus placed it at one remove from us. If we accept his doctrine, we seem to be shut up within the circle of our ideas, and can find no door that will lead us to a world outside. The question will keep coming back: How do we _know_ that, corresponding to our ideas, there are material things, if we have never perceived, in any single instance, a material thing? And the doubt here suggested may be reinforced by the reflection that the very expression "a material thing" ought to be meaningless to a man who, having never had experience of one, is compelled to represent it by the aid of something so different from it as ideas are supposed to be. Can material things really be to such a creature anything more than some complex of ideas?

The difficulties presented by any philosophical doctrine are not always evident at once. Descartes made no scruple of accepting the existence of an external world, and his example has been followed by a very large number of those who agree with his initial a.s.sumption that the mind knows immediately only its own ideas.

Preeminent among such we must regard John Locke, the English philosopher (1632-1704), whose cla.s.sic work, "An Essay concerning Human Understanding," should not be wholly unknown to any one who pretends to an interest in the English literature.

Admirably does Locke represent the position of what very many have regarded as the prudent and sensible man,--the man who recognizes that ideas are not external things, and that things must be known through ideas, and yet holds on to the existence of a material world which we a.s.suredly know.

He recognizes, it is true, that some one may find a possible opening for the expression of a doubt, but he regards the doubt as gratuitous; "I think n.o.body can, in earnest, be so skeptical as to be uncertain of the existence of those things which he sees and feels." As we have seen (section 12), he meets the doubt with a jest.

Nevertheless, those who read with attention Locke's admirably clear pages must notice that he does not succeed in really setting to rest the doubt that has suggested itself. It becomes clear that Locke felt so sure of the existence of the external world because he now and then slipped into the inconsistent doctrine that he perceived it immediately, and not merely through his ideas. Are those things "which he sees and feels" _external_ things? Does he see and feel them directly, or must he infer from his ideas that he sees and feels them?

If the latter, why may one not still doubt? Evidently the appeal is to a direct experience of material things, and Locke has forgotten that he must be a Lockian.

"I have often remarked, in many instances," writes Descartes, "that there is a great difference between an object and its idea." How could the man possibly have remarked this, when he had never in his life perceived the object corresponding to any idea, but had been altogether shut up to ideas? "Thus I see, whilst I write this," says Locke,[1] "I can change the appearance of the paper, and by designing the letters tell beforehand what new idea it shall exhibit the very next moment, by barely drawing my pen over it, which will neither appear (let me fancy as much as I will), if my hand stands still, or though I move my pen, if my eyes be shut; nor, when those characters are once made on the paper, can I choose afterward but see them as they are; that is, have the ideas of such letters as I have made. Whence it is manifest, that they are not barely the sport and play of my own imagination, when I find that the characters that were made at the pleasure of my own thought do not obey them; nor yet cease to be, whenever I shall fancy it; but continue to affect the senses constantly and regularly, according to the figures I made them."

Locke is as bad as Descartes. Evidently he regards himself as able to turn to the external world and perceive the relation that things hold to ideas. Such an inconsistency may escape the writer who has been guilty of it, but it is not likely to escape the notice of all those who come after him. Some one is sure to draw the consequences of a doctrine more rigorously, and to come to conclusions, it may be, very unpalatable to the man who propounded the doctrine in the first instance.

The type of doctrine represented by Descartes and Locke is that of _Representative Perception_. It holds that we know real external things only through their mental representatives. It has also been called _Hypothetical Realism_, because it accepts the existence of a real world, but bases our knowledge of it upon an inference from our sensations or ideas.

49. THE STEP TO IDEALISM.--The admirable clearness with which Locke writes makes it the easier for his reader to detect the untenability of his position. He uses simple language, and he never takes refuge in vague and ambiguous phrases. When he tells us that the mind is wholly shut up to its ideas, and then later a.s.sumes that it is not shut up to its ideas, but can perceive external things, we see plainly that there must be a blunder somewhere.

George Berkeley (1684-1753), Bishop of Cloyne, followed out more rigorously the consequences to be deduced from the a.s.sumption that all our direct knowledge is of ideas; and in a youthful work of the highest genius ent.i.tled "The Principles of Human Knowledge," he maintained that there is no material world at all.

When we examine with care the objects of sense, the "things" which present themselves to us, he argues, we find that they resolve themselves into sensations, or "ideas of sense." What can we mean by the word "apple," if we do not mean the group of experiences in which alone an apple is presented to us? The word is nothing else than a name for this group as a group. Take away the color, the hardness, the odor, the taste; what have we left? And color, hardness, odor, taste, and anything else that may be referred to any object as a quality, can exist, he claims, only in a perceiving mind; for such things are nothing else than sensations, and how can there be an unperceived sensation?

The things which we perceive, then, he calls complexes of ideas. Have we any reason to believe that these ideas, which exist in the mind, are to be accepted as representatives of things of a different kind, which are not mental at all? Not a shadow of a reason, says Berkeley; there is simply no basis for inference at all, and we cannot even make clear what it is that we are setting out to infer under the name of matter.

We need not, therefore, grieve over the loss of the material world, for we have suffered no loss; one cannot lose what one has never had.

Thus, the objects of human knowledge, the only things of which it means anything to speak, are: (1) Ideas of Sense; (2) Ideas of Memory and Imagination; (3) The Pa.s.sions and Operations of the Mind; and (4) The Self that perceives all These.

From Locke's position to that of Berkeley was a bold step, and it was much criticised, as well it might be. It was felt then, as it has been felt by many down to our own time, that, when we discard an external world distinct from our ideas, and admit only the world revealed in our ideas, we really do lose.

It is legitimate to criticise Berkeley, but it is not legitimate to misunderstand him; and yet the history of his doctrine may almost be called a chronicle of misconceptions. It has been a.s.sumed that he drew no distinction between real things and imaginary things, that he made the world no better than a dream, etc. Arbuthnot, Swift, and a host of the greater and lesser lights in literature, from his time to ours, have made merry over the supposed unrealities in the midst of which the Berkeleian must live.

But it should be remembered that Berkeley tried hard to do full justice to the world of things in which we actually find ourselves; not a hypothetical, inferred, unperceived world, but the world of the things we actually perceive. He distinguished carefully between what is real and what is merely imaginary, though he called both "ideas"; and he recognized something like a system of nature. And, by the argument from a.n.a.logy which we have already examined (section 41), he inferred the existence of other finite minds and of a Divine Mind.

But just as John Locke had not completely thought out the consequences which might be deduced from his own doctrines, so Berkeley left, in his turn, an opening for a successor. It was possible for that acutest of a.n.a.lysts, David Hume (1711-1776), to treat him somewhat as he had treated Locke.

Among the objects of human knowledge Berkeley had included the _self_ that perceives things. He never succeeded in making at all clear what he meant by this object; but he regarded it as a substance, and believed it to be a cause of changes in ideas, and quite different in its nature from all the ideas attributed to it. But Hume maintained that when he tried to get a good look at this self, to catch it, so to speak, and to hold it up to inspection, he could not find anything whatever save perceptions, memories, and other things of that kind.

The self is, he said, "but a bundle or collection of different perceptions which succeed each other with inconceivable rapidity, and are in a perpetual flux and movement."

As for the objects of sense, our own bodies, the chairs upon which we sit, the tables at which we write, and all the rest--these, argues Hume, we are impelled by nature to think of as existing continuously, but we have no evidence whatever to prove that they do thus exist. Are not the objects of sense, after all, only sensations or impressions?

Do we not experience these sensations or impressions interruptedly?

Who sees or feels a table continuously day after day? If the table is but a name for the experiences in question, if we have no right to infer material things behind and distinct from such experiences, are we not forced to conclude that the existence of the things that we see and feel is an interrupted one?

Hume certainly succeeded in raising more questions than he succeeded in answering. We are compelled to admire the wonderful clearness and simplicity of his style, and the acuteness of his intellect, in every chapter. But we cannot help feeling that he does injustice to the world in which we live, even when we cannot quite see what is wrong.

Does it not seem certain to science and to common sense that there is an order of nature in some sense independent of our perceptions, so that objects may be a.s.sumed to exist whether we do or do not perceive them?

When we read Hume we have a sense that we are robbed of our real external world; and his account of the mind makes us feel as a badly tied sheaf of wheat may be conceived to feel--in danger of falling apart at any moment. Berkeley we unhesitatingly call an _Idealist_, but whether we shall apply the name to Hume depends upon the extension we are willing to give to it. His world is a world of what we may broadly call _ideas_; but the tendencies of his philosophy have led some to call it a _Skepticism_.

50. THE REVOLT OF "COMMON SENSE."--Hume's reasonings were too important to be ignored, and his conclusions too unpalatable to satisfy those who came after him. It seemed necessary to seek a way of escape out of this world of mere ideas, which appeared to be so unsatisfactory a world. One of the most famous of such attempts was that made by the Scotchman Thomas Reid (1710-1796).

At one time Reid regarded himself as the disciple of Berkeley, but the consequences which Hume deduced from the principles laid down by the former led Reid to feel that he must build upon some wholly different foundation. He came to the conclusion that the line of philosophers from Descartes to Hume had made one capital error in a.s.suming "that nothing is perceived but what is in the mind that perceives it."

Once admit, says Reid, that the mind perceives nothing save ideas, and we must also admit that it is impossible to prove the existence either of an external world or of a mind different from "a bundle of perceptions." Hence, Reid maintains that we perceive--not infer, but perceive--_things_ external to the mind. He writes:[2]--

"Let a man press his hand against the table--_he feels it hard_. But what is the meaning of this? The meaning undoubtedly is, that he hath a certain feeling of touch, from which he concludes, without any reasoning, or comparing ideas, that there is something external really existing, whose parts stick so firmly together that they cannot be displaced without considerable force.

"There is here a feeling, and a conclusion drawn from it, or some way suggested by it. In order to compare these, we must view them separately, and then consider by what tie they are connected, and wherein they resemble one another. The hardness of the table is the conclusion, the feeling is the medium by which we are led to that conclusion. Let a man attend distinctly to this medium, and to the conclusion, and he will perceive them to be as unlike as any two things in nature. The one is a sensation of the mind, which can have no existence but in a sentient being; nor can it exist one moment longer than it is felt; the other is in the table, and we conclude, without any difficulty, that it was in the table before it was felt, and continues after the feeling is over. The one implies no kind of extension, nor parts, nor cohesion; the other implies all these. Both, indeed, admit of degrees, and the feeling, beyond a certain degree, is a species of pain; but adamantine hardness does not imply the least pain.

"And as the feeling hath no similitude to hardness, so neither can our reason perceive the least tie or connection between them; nor will the logician ever be able to show a reason why we should conclude hardness from this feeling, rather than softness, or any other quality whatsoever. But, in reality, all mankind are led by their const.i.tution to conclude hardness from this feeling."

It is well worth while to read this extract several times, and to ask oneself what Reid meant to say, and what he actually said. He is objecting, be it remembered, to the doctrine that the mind perceives immediately only its own ideas or sensations and must infer all else.

His contention is that we _perceive_ external things.

Does he say this? He says that we have feelings of touch _from which we conclude_ that there is something external; that there is a feeling, "_and a conclusion drawn from it, or some way suggested by it_;" that "the hardness of the table is the _conclusion_, and the feeling is the _medium_ by which we are _led to the conclusion_."

Could Descartes or Locke have more plainly supported the doctrine of representative perception? How could Reid imagine he was combatting that doctrine when he wrote thus? The point in which he differs from them is this: he maintains that we draw the conclusion in question without any reasoning, and, indeed, in the absence of any conceivable reason why we should draw it. We do it instinctively; we are led by the const.i.tution of our nature.

In effect Reid says to us: When you lay your hand on the table, you have a sensation, it is true, but you also know the table is hard. How do you know it? I cannot tell you; you simply know it, and cannot help knowing it; and that is the end of the matter.

Reid's doctrine was not without its effect upon other philosophers.

Among them we must place Sir William Hamilton (1788-1856), whose writings had no little influence upon British philosophy in the last half of the last century.

Hamilton complained that Reid did not succeed in being a very good _Natural Realist_, and that he slipped unconsciously into the position he was concerned to condemn. Sir William tried to eliminate this error, but the careful reader of his works will find to his amus.e.m.e.nt that this learned author gets his feet upon the same slippery descent.

And much the same thing may be said of the doctrine of Herbert Spencer (1820-1903), who claims that, when we have a sensation, we know directly that there is an external thing, and then manages to sublimate that external thing into an Unknowable, which we not only do not know directly, but even do not know at all.

All of these men were anxious to avoid what they regarded as the perils of Idealism, and yet they seem quite unable to retain a foothold upon the position which they consider the safer one.

Reid called his doctrine the philosophy of "Common Sense," and he thought he was coming back from the subtleties of the metaphysicians to the standpoint of the plain man. That he should fall into difficulties and inconsistencies is by no means surprising. As we have seen (section 12), the thought of the plain man is far from clear. He certainly believes that we perceive an external world of things, and the inconsistent way in which Descartes and Locke appeal from ideas to the things themselves does not strike him as unnatural. Why should not a man test his ideas by turning to things and comparing the former with the latter? On the other hand, he knows that to perceive things we must have sense organs and sensations, and he cannot quarrel with the psychologists for saying that we know things only in so far as they are revealed to us through our sensations. How does he reconcile these two positions? He does not reconcile them. He accepts them as they stand.

Reid and various other philosophers have tried to come back to "Common Sense" and to stay there. Now, it is a good position to come back to for the purpose of starting out again. The experience of the plain man, the truths which he recognizes as truths, these are not things to be despised. Many a man whose mind has been, as Berkeley expresses it, "debauched by learning," has gotten away from them to his detriment, and has said very unreasonable things. But "Common Sense" cannot be the ultimate refuge of the philosopher; it can only serve him as material for investigation. The scholar whose thought is as vague and inconsistent as that of the plain man has little profit in the fact that the apparatus of his learning has made it possible for him to be ponderously and unintelligibly vague and inconsistent.

Hence, we may have the utmost sympathy with Reid's protest against the doctrine of representative perception, and we may, nevertheless, complain that he has done little to explain how it is that we directly know external things and yet cannot be said to know things except in so far as we have sensations or ideas.