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2012年2月19日 星期日

The Problems of Philosophy - Chapter Four


The Problems of Philosophy - Chapter Four


Book: The Problems of Philosophy
Author: Bertrand Russell

Chapter Four

Idealism

THE word 'idealism' is used by different philosophers in somewhat different senses. We shall understand by it the doctrine that whatever exists, or at any rate whatever can be known to exist, must be in some sense mental. This doctrine, which is very widely held among philosophers, has several forms, and is advocated on several different grounds. The doctrine is so widely held, and so interesting in itself, that even the briefest survey of philosophy must give some account of it.

Those who are unaccustomed to philosophical speculation may be inclined to dismiss such a doctrine as obviously absurd. There is no doubt that common sense regards tables and chairs and the sun and moon and material objects generally as something radically different from minds and the contents of minds, and as having an existence which might continue if minds ceased. We think of matter as having existed long before there were any minds, and it is hard to think of it as a mere product of mental activity. But whether true or false, idealism is not to be dismissed as obviously absurd.

The key idea of these two paragraph is: for anything can be known to exist, must be in some sense mental.

We have seen that, even if physical objects do have an independent existence, they must differ very widely from sense-data, and can only have a correspondence with sense-data, in the same sort of way in which a catalogue has a correspondence with the things catalogued. Hence common sense leaves us completely in the dark as to the true intrinsic nature of physical objects, and if there were good reason to regard them as mental, we could not legitimately reject this opinion merely because it strikes us as strange. The truth about physical objects must be strange. It may be unattainable, but if any philosopher believes that he has attained it, the fact that what he offers as the truth is strange ought not to be made a ground of objection to his opinion.

TRUTH of physical objects (or I would call it REALITY) must be strange because we cannot deny the fact that when we try to understanding the REALITY, it must pass through our MIND. The REALITY is unattainable because all the thinking and imagination only exists in our MIND.

The grounds on which idealism is advocated are generally grounds derived from the theory of knowledge, that is to say, from a discussion of the conditions which things must satisfy in order that we may be able to know them. The first serious attempt to establish idealism on such grounds was that of Bishop Berkeley. He proved first, by arguments which were largely valid, that our sense-data cannot be supposed to have an existence independent of us, but must be, in part at least, 'in' the mind, in the sense that their existence would not continue if there were no seeing or hearing or touching or smelling or tasting. So far, his contention was almost certainly valid, even if some of his arguments were not so. But he went on to argue that sense-data were the only things of whose existence our perceptions could assure us, and that to be known is to be 'in' a mind, and therefore to be mental. Hence he concluded that nothing can ever be known except what is in some mind, and that whatever is known without being in my mind must be in some other mind.

REALITY -> sense data -> MIND -> language -> Representation
     <---------------------------------------------------------/

What's Berkeley's mistake here (the underlined part)?  
Firstly, we can only conclude that "I know something if it is in my mind", but it doesn't guaranteed that I have confidence to believe that "Something can be known if it is in some's mind". Put a step forward, even if the first and second statements are true, it is too far to jump to Berkeley's idea: "Therefore, god exists and everything is being in the god' mind". 

In order to understand his argument, it is necessary to understand his use of the word 'idea'. He gives the name 'idea' to anything which is immediately known, as, for example, sense-data are known Thus a particular colour which we see is an idea; so is a voice which we hear, and so on. But the term is not wholly confined to sense-data. There will also be things remembered or imagined, for with such things also we have immediate acquaintance at the moment of remembering or imagining. All such immediate data he calls 'ideas'.

He then proceeds to consider common objects, such as a tree, for instance. He shows that all we know immediately when we 'perceive' the tree consists of ideas in his sense of the word, and he argues that there is not the slightest ground for supposing that there is anything real about the tree except what is perceived. Its being, he says, consists in being perceived: in the Latin of the schoolmen its 'esse' is 'percipi'. He fully admits that the tree must continue to exist even when we shut our eyes or when no human being is near it. But this continued existence, he says, is due to the fact that God continues to perceive it; the 'real' tree, which corresponds to what we called the physical object, consists of ideas in the mind of God, ideas more or less like those we have when we see the tree, but differing in the fact that they are permanent in God's mind so long as the tree continues to exist. All our perceptions, according to him, consist in a partial participation in God's perceptions, and it is because of this participation that different people see more or less the same tree. Thus apart from minds and their ideas there is nothing in the world, nor is it possible that anything else should ever be known, since whatever is known is necessarily an idea.

There are in this argument a good many fallacies which have been important in the history of philosophy, and which it will be as well to bring to light. In the first place, there is a confusion engendered by the use of the word 'idea'. We think of an idea as essentially something in somebody's mind, and thus when we are told that a tree consists entirely of ideas, it is natural to suppose that, if so, the tree must be entirely in minds. But the notion of being 'in' the mind is ambiguous. We speak of bearing a person in mind, not meaning that the person is in our minds, but that a thought of him is in our minds. When a man says that some business he had to arrange went clean out of his mind, he does not mean to imply that the business itself was ever in his mind, but only that a thought of the business was formerly in his mind, but afterwards ceased to be in his mind. And so when Berkeley says that the tree must be in our minds if we can know it, all that he really has a right to say is that a thought of the tree must be in our minds. To argue that the tree itself must be in our minds is like arguing that a person whom we bear in mind is himself in our minds. This confusion may seem too gross to have been really committed by any competent philosopher, but various attendant circumstances rendered it possible. In order to see how it was possible, we must go more deeply into the question as to the nature of ideas.

Russell denies Berkeley's idea by analyzing Berkeley's definition of "idea". That is, the word "known" now means that "a thought of something is in mind" but not "something (materially) is in my mind".

Before taking up the general question of the nature of ideas, we must disentangle two entirely separate questions which arise concerning sense-data and physical objects. We saw that, for various reasons of detail, Berkeley was right in treating the sense-data which constitute our perception of the tree as more or less subjective, in the sense that they depend upon us as much as upon the tree, and would not exist if the tree were not being perceived. But this is an entirely different point from the one by which Berkeley seeks to prove that whatever can be immediately known must be in a mind. For this purpose argument of detail as to the dependence of sense-data upon us are useless. It is necessary to prove, generally, that by being known, things are shown to be mental. This is what Berkeley believes himself to have done. It is this question, and not our previous question as to the difference between sense-data and the physical object, that must now concern us.


Taking the word 'idea' in Berkeley's sense, there are two quite distinct things to be considered whenever an idea is before the mind. There is on the one hand the thing of which we are aware -- say the colour of my table -- and on the other hand the actual awareness itself, the mental act of apprehending the thing. The mental act is undoubtedly mental, but is there any reason to suppose that the thing apprehended is in any sense mental? Our previous arguments concerning the colour did not prove it to be mental; they only proved that its existence depends upon the relation of our sense organs to the physical object -- in our case, the table. That is to say, they proved that a certain colour will exist, in a certain light, if a normal eye is placed at a certain point relatively to the table. They did not prove that the colour is in the mind of the percipient.

Berkeley's view, that obviously the colour must be in the mind, seems to depend for its plausibility upon confusing the thing apprehended with the act of apprehension. Either of these might be called an 'idea'; probably either would have been called an idea by Berkeley. The act is undoubtedly in the mind; hence, when we are thinking of the act, we readily assent to the view that ideas must be in the mind. Then, forgetting that this was only true when ideas were taken as acts of apprehension, we transfer the proposition that 'ideas are in the mind' to ideas in the other sense, i.e. to the things apprehended by our acts of apprehension. Thus, by an unconscious equivocation, we arrive at the conclusion that whatever we can apprehend must be in our minds. This seems to be the true analysis of Berkeley's argument, and the ultimate fallacy upon which it rests.

This question of the distinction between act and object in our apprehending of things is vitally important, since our whole power of acquiring knowledge is bound up with it. The faculty of being acquainted with things other than itself is the main characteristic of a mind. Acquaintance with objects essentially consists in a relation between the mind and something other than the mind; it is this that constitutes the mind's power of knowing things. If we say that the things known must be in the mind, we are either unduly limiting the mind's power of knowing, or we are uttering a mere tautology. We are uttering a mere tautology if we mean by 'in the mind' the same as by 'before the mind', i.e. if we mean merely being apprehended by the mind. But if we mean this, we shall have to admit that what, in this sense, is in the mind, may nevertheless be not mental. Thus when we realize the nature of knowledge, Berkeley's argument is seen to be wrong in substance as well as in form, and his grounds for supposing that 'ideas' -- i.e. the objects apprehended -- must be mental, are found to have no validity whatever. Hence his grounds in favour of idealism may be dismissed. It remains to see whether there are any other grounds.

It is often said, as though it were a self-evident truism, that we cannot know that anything exists which we do not know. It is inferred that whatever can in any way be relevant to our experience must be at least capable of being known by us; whence it follows that if matter were essentially something with which we could not become acquainted, matter would be something which we could not know to exist, and which could have for us no importance whatever. It is generally also implied, for reasons which remain obscure, that what can have no importance for us cannot be real, and that therefore matter, if it is not composed of minds or of mental ideas, is impossible and a mere chimaera.

To go into this argument fully at our present stage would be impossible, since it raises points requiring a considerable preliminary discussion; but certain reasons for rejecting the argument may be noticed at once. To begin at the end: there is no reason why what cannot have any practical importance for us should not be real. It is true that, if theoretical importance is included, everything real is of some importance to us, since, as persons desirous of knowing the truth about the universe, we have some interest in everything that the universe contains. But if this sort of interest is included, it is not the case that matter has no importance for us, provided it exists even if we cannot know that it exists. We can, obviously, suspect that it may exist, and wonder whether it does; hence it is connected with our desire for knowledge, and has the importance of either satisfying or thwarting this desire.


For example, the existence of high dimension!

Again, it is by no means a truism, and is in fact false, that we cannot know that anything exists which we do not know. The word 'know' is here used in two different senses. (1) In its first use it is applicable to the sort of knowledge which is opposed to error, the sense in which what we know is true, the sense which applies to our beliefs and convictions, i.e. to what are called judgements. In this sense of the word we know that something is the case. This sort of knowledge may be described as knowledge of truths. (2) In the second use of the word 'know' above, the word applies to our knowledge of things, which we may call acquaintance. This is the sense in which we know sense-data. (The distinction involved is roughly that between savoir and connaître in French, or betweenwissen and kennen in German.)

Thus the statement which seemed like a truism becomes, when re-stated, the following: 'We can never truly judge that something with which we are not acquainted exists.' This is by no means a truism, but on the contrary a palpable falsehood. I have not the honour to be acquainted with the Emperor of China, but I truly judge that he exists. It may be said, of course, that I judge this because of other people's acquaintance with him. This, however, would be an irrelevant retort, since, if the principle were true, I could not know that any one else is acquainted with him. But further: there is no reason why I should not know of the existence of something with which nobody is acquainted. This point is important, and demands elucidation.

If I am acquainted with a thing which exists, my acquaintance gives me the knowledge that it exists. But it is not true that, conversely, whenever I can know that a thing of a certain sort exists, I or some one else must be acquainted with the thing. What happens, in cases where I have true judgement without acquaintance, is that the thing is known to me by description, and that, in virtue of some general principle, the existence of a thing answering to this description can be inferred from the existence of something with which I am acquainted. In order to understand this point fully, it will be well first to deal with the difference between knowledge by acquaintance and knowledge by description, and then to consider what knowledge of general principles, if any, has the same kind of certainty as our knowledge of the existence of our own experiences. These subjects will be dealt with in the following chapters.






2012年2月8日 星期三

社會學理論 - 第一篇 (In progress)



書名:社會學理論
作者:George Ritzer
譯者:馮康莊、陳信木

第一篇為導論,主要介紹了美國不同的社會學派系及影響力最大之幾為社會學家。書中一開始即開門見山地扼要簡述了一些各家理論的精華:

1. 現代社會是個理性體系的鐵籠,無人可在其中逃脫
2. 資本主義種下了自我毀滅的種子
3. 現代世界較之古老社會缺乏道德凝聚
4. 都市產生獨特形式的人格
5. 社會生活中,人類扮演不同的舞台角色
6. 社會世界由取與授之相互關係原則所界定
7. 人類創造了社會世界,最後卻為其所奴役
8. 人類總是保留改變這個強制他的社會世界之能力

扼要而言,社會學受科學方法的影響甚深。引用原文:

「啟蒙時代後期的思想家,企圖將經驗研究 (empirical research) 與理性 (reason) 結合。此一目的之典型手段就是科學,尤其是牛頓物理學。」

「總括而言,啟蒙時代的特色是相信人類可以借由理性與經驗研究手段,而綜合理解與控制宇宙。而且,由於物質世界係由自然法則所支配,因此,社會世界亦有可能存在類似的法則。」

法國的三名社會學家

1. 聖西門 (Claude Henri Saint-Simon)
表現「實證主義者」之態度,堅持研究社會現象必須比照自然科學用某些科學技術

2. 孔德 (Auguste Comte)
針對法國革命和啟蒙時代反動而生,發明了實證主義 (positivism)
同時著重社會靜學 (social statics) 和社會動學 (social dynamics),前者探討社會結構,後者探討社會變遷
「三階段法則」:神學階段(所有事物為上帝所造)、玄學階段(重視形而上思辨)、實證主義階段(放棄尋求絕對因而專注於社會與物質世界的觀察)

3. 涂爾幹 (Emile Durkheim)
保守主義者。與馬克思相反,認為現代世界的問題不內含於社會之中,主張改革。
涂爾幹在《社會學方法論》指出社會學的特殊使命就是研究「社會事實」(Social facts)
何謂社會事實?涂爾幹認為社會事實就是外在於強制個體的力量和結構

馬克思與德國社會學

馬克思唯物辯證法

黑格爾的兩個哲學本質概念為辯證法與觀念論,馬克思捨棄其觀念部分而重視物質世界

黑格爾認為人類只是稟賦一種能力能對其周遭的世界進行感覺上的理解 (sensory understanding)。他們所能理解的只是光、味一類而已,只能感覺到社會與物質世界。而後人類發展另一種能力嘗試去意識和諒解其自身,人類開始可以變得超越自己的過去和現在。以黑格爾辯證法字彙而言,人類至此出現了一種「矛盾」,發生在他過去所存在的實在和現今他所能感覺能夠變成的狀態之間。這一矛盾導致發展了個體知覺,個體因而意識到其在社會精神中所處的位置。

黑格爾的演化觀念強調變遷只發生在意識層次,超越了個體的控制能力:個體只是順著不可避免的意識演化之激流脈動。

費爾巴哈為馬克思與黑格爾之橋樑。他重視人類的物質實在 (material reality)。

黑格爾視社會事實如財富和國家為觀念而非真實的物質實體,所以當黑格爾檢驗類似勞動一類表面上似乎為物質過程的事物時,黑格爾也只是將其視為抽像的心智勞動。

黑格爾將人類變成「自我意識下的人」 (man of self-consciousness),而非將自我意識還原為「人的自我意識」 (self-consciousness of man),可是人類卻是生活在真實的客觀世界裡且受這個世界所制約和主宰。換言之,黑格爾將這個世界存在於他的「頭顱上」;所以,一切「真實的人」(real man)所存在.....自然留下的限制,黑格爾都可以在他的「腦袋裡」解決。
(Marx and Engels, 1845/1956: 254)

唯物辯證論之焦點在於探討物質世界的辯證關係。

馬克思之「唯物」之主要關切在經濟領域,因此深受如亞當斯密及李嘉圖等人之影響。馬克思相信勞力是一切財富的來源,使其完成著名「勞動價值理論」(labor theory of value),強調資本家的利潤乃是基於對勞工之剝削而來;資本主義隨著對工人剝削成度的持續增加而成長(即剩餘價值總量的增加)

辯證法:非線性的 A->B 的思考,重視 A->B 而後 B反施於A 的影響

2012年1月31日 星期二

The Problems of Philosophy - Chapter One (In Progress)

Book: The Problems of Philosophy
Author: Bertrand Russell

Chapter One

Appearance and Reality

Is there any knowledge in the world which is so certain that no reasonable man could doubt it? This question, which at first sight might not seem difficult, is really one of the most difficult that can be asked. When we have realized the obstacles in the way of a straightforward and confident answer,we shall be well launched on the study of philosophy--for philosophy is merely the attempt to answer such ultimate questions, not carelessly and dogmatically, as we do in ordinary life and even in the sciences, but critically, after exploring all that makes such questions puzzling, and after realizing all the vagueness and confusion that underlie our ordinary ideas.

According to Russell, Philosophy is a subject that tries to find some knowledge which is no reasonable man could doubt it.
Why our ordinary ideas are vague and confusing? For example, think about "blue". It may seems in the beginning that "blue" is a concept that easy to understand. However, when you think
deeply, there exists "pale blue", "deep blue", "greenish blue". If you have studied physics, you know that "color" is actually some electromagnetic wave that strikes our eyes, passing through our nerves and finally becomes image in our brain. Therefore, since electromagnetic wave has so many different frequencies (infinity!), there exists infinity "blues".

The same problem exists for many terms we use in our daily life, for example: Just. In some situation, such as "Zhao Lian Hai"'s incident in China, we are easy to figure out it is unjust to send him into the prison. However, in some critical cases, such as the "Dudley and Stephens" case, four men were isolated in an island and they have no food to eat. Due to hunger, three of them killed a boy for food. After rescue, they were judged to be guilty, but the punishment is light. Can we easily say that the judgement is "Just"? We have to make the word more clear and certain so that we can decide whether it is correct or not.

In daily life, we assume as certain many things which, on a closer scrutiny, are found to be so full of apparent contradictions that only a great amount of thought enables us to know what it is that we really may believe. In the search for certainty, it is natural to begin with our present experiences, and in some sense, no doubt, knowledge is to be derived from them. But any statement as to what it is that our immediate experiences make us know is very likely to be wrong. It seems to me that I am now sitting in a chair, at a table of a certain shape, on which I see sheets of paper with writing or print. By turning my head I see out of the window buildings and clouds and the sun. I believe that the sun is about ninety-three million miles from the earth; that it is a hot globe many times bigger than the earth; that, owing to the earth's rotation, it rises every morning, and will continue to do so for an indefinite time in the future. I believe that, if any other normal person comes into my room, he will see the same chairs and tables and books and papers as I see, and that the table which I see is the same as the table which I feel pressing against my arm. All this seems to be so evident as to be hardly worth stating, except in answer to a man who doubts whether I know anything. Yet all this may be reasonably doubted, and all of it requires much careful discussion before we can be sure that we have stated it in a form that is wholly true.


Here, Russell points out an important facts that "our daily knowledge is to be derived from our experience". However, as Descartes said, all sensations can be reasonably doubt. Our sensation may deceive us, just as some optical illusion games that you have played: The two yellow lines are of the same length.

Therefore, our sensation may not be "correct". Then it becomes strange. If we do not believe our sensation, then what should we believe in? Science? But why science is "correct"?

To make our difficulties plain, let us concentrate attention on the table. To the eye it is oblong, brown and shiny, to the touch it is smooth and cool and hard; when I tap it, it gives out a wooden sound. Any one else who sees and feels and hears the table will agree with this description, so that it might seem as if no difficulty would arise; but as soon as we try to be more precise our troubles begin. Although I believe that the table is 'really' of the same colour all over, the parts that reflect the light look much brighter than the other parts, and some parts look white because of reflected light. I know that, if I move, the parts that reflect the light will be different, so that the apparent distribution of colours on the table will change. It follows that if several people are looking at the table at the same moment, no two of them will see exactly the same distribution of colours, because no two can see it from exactly the same point of view, and any change in the point of view makes some change in the way the light is reflected.

Russell here points out that knowledge comes from our sensation can be actually different. It depends on the observer and the environment during observation. No two people can see a table that is completely the same.

For most practical purposes these differences are unimportant, but to the painter they are all-important: the painter has to unlearn the habit of thinking that things seem to have the colour which common sense says they 'really' have, and to learn the habit of seeing things as they appear. Here we have already the beginning of one of the distinctions that cause most trouble in philosophy--the distinction between 'appearance' and 'reality', between what things seem to be and what they are. The painter wants to know what things seem to be, the practical man and the philosopher want to know what they are; but the philosopher's wish to know this is stronger than the practical man's, and is more troubled by knowledge as to the difficulties of answering the question.

Here, I guess that Russell said that "Truth" is hidden in reality, just as the painter, they can see color which are more concise than normal people. It is not because they are special or talented, but they are well aware of the vagueness of the "daily language" and able to distinguish "reality" (terms that are concise) from the "appearance" (terms that are vague).

To return to the table. It is evident from what we have found, that there is no colour which pre-eminently appears to be the colour of the table, or even of any one particular part of the table--it appears to be of different colours from different points of view, and there is no reason for regarding some of these as more really its colour than others. And we know that even from a given point of view the colour will seem different by artificial light, or to a colour-blind man, or to a man wearing blue spectacles, while in the dark there will be no colour at all, though to touch and hearing the table will be unchanged. This colour is not something which is inherent in the table, but something depending upon the table and the spectator and the way the light falls on the table. When, in ordinary life, we speak of the colour of the table, we only mean the sort of colour which it will seem to have to a normal spectator from an ordinary point of view under usual conditions of light. But the other colours which appear under other conditions have just as good a right to be considered real; and therefore, to avoid favouritism, we are compelled to deny that, in itself, the table has any one particular colour.

Again, knowledge comes from our sensation can be different. It depends on the observer and the environment during observation. If we consider our sensation to be absolutely correct, then the conclusion is: the table has any one particular colour (all different colors of "blue").

The same thing applies to the texture. With the naked eye one can see the grain, but otherwise the table looks smooth and even. If we looked at it through a microscope, we should see roughnesses and hills and valleys, and all sorts of differences that are imperceptible to the naked eye. Which of these is the 'real' table? We are naturally tempted to say that what we see through the microscope is more real, but that in turn would be changed by a still more powerful microscope. If, then, we cannot trust what we see with the naked eye, why should we trust what we see through a microscope? Thus, again, the confidence in our senses with which we began deserts us.

Sensation and science are both not reliable. It seems that it becomes a difficult problem for we to believe that something is absolutely correct. We have to find some rules, or criteria, to judge whether a sentence is correct.

The shape of the table is no better. We are all in the habit of judging as to the 'real' shapes of things, and we do this so unreflectingly that we come to think we actually see the real shapes. But, in fact, as we all have to learn if we try to draw, a given thing looks different in shape from every different point of view. If our table is 'really' rectangular, it will look, from almost all points of view, as if it had two acute angles and two obtuse angles. If opposite sides are parallel, they will look as if they converged to a point away from the spectator; if they are of equal length, they will look as if the nearer side were longer. All these things are not commonly noticed in looking at a table, because experience has taught us to construct the 'real' shape from the apparent shape, and the 'real' shape is what interests us as practical men. But the 'real' shape is not what we see; it is something inferred from what we see. And what we see is constantly changing in shape as we move about the room; so that here again the senses seem not to give us the truth about the table itself, but only about the appearance of the table.




The figure on the right demonstrates different views of a table, I copied it from Wikipedia. The three view are trimetric, dimetric and isometric, which represent different angles from viewing the desk. You can imagine that you can only see a real rectangle from the top view. In other view, what we see are not rectangle, but parallelogram, or trapezoid, etc.. It is from our acquired knowledge that we have learnt the real shape of table - "Rectangle". It is an abstract concept, but not concrete experience. As what plato said, the complete, perfect "Rectangle" only exists in our mind, but not in reality.




Similar difficulties arise when we consider the sense of touch. It is true that the table always gives us a sensation of hardness, and we feel that it resists pressure. But the sensation we obtain depends upon how hard we press the table and also upon what part of the body we press with; thus the various sensations due to various pressures or various parts of the body cannot be supposed to reveal directly any definite property of the table, but at most to be signs of some property which perhaps causes all the sensations, but is not actually apparent in any of them. And the same applies still more obviously to the sounds which can be elicited by rapping the table.

Thus it becomes evident that the real table, if there is one, is not the same as what we immediately experience by sight or touch or hearing. The real table, if there is one, is not immediately known to us at all, but must be an inference from what is immediately known. Hence, two very difficult questions at once arise; namely, (1) Is there a real table at all? (2) If so, what sort of object can it be?


Here comes the conflicts between "reality" and "appearance". "Reality" is the "real world", or I would say, a pure idea only exists in our mind, but appearance is "how the world seems to appear to myself", the concrete experience.

It will help us in considering these questions to have a few simple terms of which the meaning is definite and clear. Let us give the name of 'sense-data' to the things that are immediately known in sensation: such things as colours, sounds, smells, hardnesses, roughnesses, and so on. We shall give the name 'sensation' to the experience of being immediately aware of these things. Thus, whenever we see a colour, we have a sensation of the colour, but the colour itself is a sense-datum, not a sensation. The colour is that of which we are immediately aware, and the awareness itself is the sensation. It is plain that if we are to know anything about the table, it must be by means of the sense-data--brown colour, oblong shape, smoothness, etc.--which we associate with the table; but, for the reasons which have been given, we cannot say that the table is the sense-data, or even that the sense-data are directly properties of the table. Thus a problem arises as to the relation of the sense-data to the real table, supposing there is such a thing.