A DEFENCE OF COMMON
In what follows I have merely tried to state, one by one, some of the most important points in which my philosophical position differs from positions which have been taken up by some other philosophers. It may be that the points which I have had room to mention are not really the most important, and possibly some of them may be points as to which no philosopher has ever really differed from me. But, to the best of my belief, each is a point as to which many have really differed; although (in most cases, at all events) each is also a point as to which many have agreed with me.
I. The first point is a point which embraces a great many other points. And it is one which I cannot state as clearly as I wish to state it, except at some length. The method I am going to use for stating it is this. I am going to begin by enunciating, under the heading (1), a whole long list of propositions, which may seem, at first sight, such obvious truisms as not to be worth stating: they are, in fact, a set of propositions, every one of which (in my own opinion) I know, with certainty, to be true. I shall, next, under the heading (2), state a single proposition which makes an assertion about a whole set of classes of propositions - each class being defined, as the class consisting of all propositions which resemble one of the propositions in (1) in a certain respect. (2), therefore, is a proposition which could not be stated, until the list of propositions in (1), or some similar list, had already been given. (2) is itself a proposition which may seem such an
Originally published in Contemporary British Philosophy (second series), ed. J.H. Muirhead (George Allen & Unwin, London: 1925), pp.192-233.
A DEFENCE OF COMMON SENSE
obvious truism as not to be worth stating: and it is also a proposition which (in my own opinion) I know, with certainty, to be true. But, nevertheless, it is, to the best of my belief, a proposition with regard to which many philosophers have, for different reasons, differed from me; even if they have not directly denied (2) itself, they have held views incompatible with it. My first point, then, may be said to be that (2), together with all its implications, some of which I shall expressly mention, is true.
(1) I begin, then, with my list of truisms, every one of which (in my own opinion) I know, with certainty, to be true. The propositions to be included in this list are the following:
There exists at present a living human body, which is my body. This body was born at a certain time in the past, and has existed continuously ever since, though not without undergoing changes; it was, for instance, much smaller when it was born, and for some time afterwards, than it is now. Ever since it was born, it has been either in contact with or not far from the surface of the earth; and, at every moment since it was born, there have also existed many other things, having shape and size in three dimensions (in the same familiar sense in which it has), from which it has been at various distances (in the familiar sense in which it is now at a distance both from that mantelpiece and from that bookcase, and at a greater distance from the bookcase than it is from the mantelpiece); also there have (very often, at all events) existed some other things of this kind with which it was in contact (in the familiar sense in which it is now in contact with the pen I am holding in my right hand and with some of the clothes I am wearing). Among the things which have, in this sense, formed part of its environment (i.e., have been either in contact with it, or at some distance from it, however great) there have, at every moment since its birth, been large numbers of other living human bodies, each of which has, like it, (a) at some time been born, (b) continued to exist from some time after birth, (c) been, at every moment of its life after birth, either in contact with or not far from the surface of the earth; and many of these bodies have already died and ceased to exist. But the earth had existed also for many years before my body was born; and for many of these years, also, large numbers of human bodies had, at every moment, been alive upon it; and many of these bodies had died and ceased to exist before it was
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born. Finally (to come to a different class of propositions), I am a human being, and I have, at different times since my body was born, had many different experiences, of each of many different kinds: e.g., I have often perceived both my own body and other things which formed part of its environment, including other human bodies; I have not only perceived things of this kind, but have also observed facts about them, such as, for instance, the fact which I am now observing, that that mantelpiece is at present nearer to my body than that bookcase; I have been aware of other facts, which I was not at the time observing, such as, for instance, the fact, of which I am now aware, that my body existed yesterday and was then also for some time nearer to that mantelpiece than to that bookcase; I have had expectations with regard to the future, and many beliefs of other kinds, both true and false; I have thought of imaginary things and persons and incidents, in the reality of which I did not believe; I have had dreams; and I have had feelings of many different kinds. And, just as my body has been the body of a human being, namely myself, who has, during his lifetime, had many experiences of each of these (and other) different kinds; so, in the case of very many of the other human bodies which have lived upon the earth, each has been the body of a different human being, who has, during the lifetime of that body, had many different experiences of each of these (and other) different kinds.
(2) I now come to the single truism which, as will be seen, could not be stated except by reference to the whole list of truisms, just given in (1). This truism also (in my own opinion) I know, with certainty, to be true; and it is as follows:
In the case of very many (I do not say all) of the human beings belonging to the class (which includes myself) defined in the following way, i.e., as human beings who have had human bodies, that were born and lived for some time upon the earth, and who have, during the lifetime of those bodies, had many different experiences of each of the kinds mentioned in (1), it is true that each has frequently, during the life of his body, known, with regard to himself or his body, and with regard to some time earlier than any of the times at which I wrote down the propositions in (1), a proposition corresponding to each of the propositions in (1), in the sense that it asserts with regard to himself or his body and the earlier time in question (namely, in
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each case, the time at which he knew it), just what the corresponding proposition in (1) asserts with regard to me or my body and the time at which I wrote that proposition down.
In other words what (2) asserts is only (what seems an obvious enough truism) that each of us (meaning by 'us', very many human beings of the class defined) has frequently known, with regard to himself or his body and the time at which he knew it, everything which, in writing down my list of propositions in (1), I was claiming to know about myself or my body and the time at which I wrote that proposition down, i.e., just as I knew (when I wrote it down) 'There exists at present a living human body which is my body', so each of us has frequently known with regard to himself and some other time the different but corresponding proposition, which he could then have properly expressed by, 'There exists at present a human body which is my body'; just as I know 'Many human bodies other than mine have before now lived on the earth', so each of us has frequently known the different but corresponding proposition 'Many human bodies other than mine have before now lived on the earth'; just as I know 'Many human beings other than myself have before now perceived, and dreamed, and felt', so each of us has frequently known the different but corresponding proposition 'Many human beings other than myself have before now perceived, and dreamed, and felt'; and so on, in the case of each of the propositions enumerated in (1).
I hope there is no difficulty in understanding, so far, what this proposition (2) asserts. I have tried to make dear by examples what I mean by 'propositions corresponding to each of the propositions in (1)'. And what (2) asserts is merely that each of us has frequently known to be true a proposition corresponding (in that sense) to each of the propositions in (1) - a different corresponding proposition, of course, at each of the times at which he knew such a proposition to be true.
But there remain two points, which, in view of the way in which some philosophers have used the English language, ought, I think, to be expressly mentioned, if I am to make quite clear exactly how much I am asserting in asserting (2).
The first point is this. Some philosophers seem to have thought it legitimate to use the word 'true' in such a sense that a proposition which is partially false may nevertheless also be true; and some of these, therefore, would perhaps say that
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propositions like those enumerated in (1) are, in their view, true, when all the time they believe that every such proposition is partially false. I wish, therefore, to make it quite plain that I am not using 'true' in any such sense. I am using it in such a sense (and I think this is the ordinary usage) that if a proposition is partially false, it follows that it is not true, though, of course, it may be partially true. I am maintaining, in short, that all the propositions in (1), and also many propositions corresponding to each of these, are wholly true; I am asserting this in asserting (2). And hence any philosopher, who does in fact believe, with regard to any or all of these classes of propositions, that every proposition of the class in question is partially false, is, in fact, disagreeing with me and holding a view incompatible with (2), even though he may think himself justified in saying that he believes some propositions belonging to all of these classes to be 'true'.
And the second point is this. Some philosophers seem to have thought it legitimate to use such expressions as, e.g. 'The earth has existed for many years past, as if they expressed something which they really believed, when in fact they believe that every proposition, which such an expression would ordinarily be understood to express, is, at least partially, false; and all they really believe is that there is some other set of propositions, related in a certain way to those which such expressions do actually express, which, unlike these, really are true. That is to say, they use the expression 'The earth has existed for many years past' to express, not what it would ordinarily be understood to express, but the proposition that some proposition, related to this in a certain way, is true; when all the time they believe that the proposition, which this expression would ordinarily be understood to express, is, at least partially, false. I wish, therefore, to make it quite plain that I was not using the expressions I used in (1) in any such subtle sense. I meant by each of them precisely what every reader, in reading them, will have understood me to mean. And any philosopher, therefore, who holds that any of these expressions, if understood in this popular manner, expresses a proposition which embodies some popular error, is disagreeing with me and holding a view incompatible with (2), even though he may hold that there is some other, true, proposition which the expression in question might be legitimately used to express.
A DEFENCE OF COMMON SENSE
In what I have just said, I have assumed that there is some meaning which is the ordinary or popular meaning of such expressions as 'The earth has existed for many years past'. And this, I am afraid, is an assumption which some philosophers are capable of disputing. They seem to think that the question 'Do you believe that the earth has existed for many years past?' is not a plain question, such as should be met either by a plain 'Yes' or 'No', or by a plain 'I can't make up my mind', but is the sort of question which can be properly met by: 'It all depends on what you mean by "the earth" and "exists" and "years": if you mean so and so, and so and so, and so and so, then I do; but if you mean so and so, and so and so, and so and so, or so and so, and so and so, and so and so, or so and so, and so and so, and so and so, then I don't, or at least I think it is extremely doubtful'. It seems to me that such a view is as profoundly mistaken as any view can be. Such an expression as 'The earth has existed for many years past' is the very type of an unambiguous expression, the meaning of which we all understand. Anyone who takes a contrary view must, I suppose, be confusing the question whether we understand its meaning (which we all certainly do) with the entirely different question whether we know what it means, in the sense that we are able to give a correct analysis of its meaning. The question what is the correct analysis of the proposition meant on any occasion (for, of course, as I insisted in defining (2), a different proposition is meant at every different time at which the expression is used) by 'The earth has existed for many years past' is, it seems to me, a profoundly difficult question, and one to which, as I shall presently urge, no one knows the answer. But to hold that we do not know what, in certain respects, is the analysis of what we understand by such an expression, is an entirely different thing from holding that we do not understand the expression. It is obvious that we cannot even raise the question how what we do understand by it is to be analysed, unless we do understand it. So soon, therefore, as we know that a person who uses such an expression is using it in its ordinary sense, we understand his meaning. So that in explaining that I was using the expressions used in (1) in their ordinary sense (those of them which have an ordinary sense, which is not the case with quite all of them), I have done all that is required to make my meaning dear.
But now, assuming that the expressions which I have used to
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express (2) are understood, I think, as I have said, that many philosophers have really held views incompatible with (2). And the philosophers who have done so may, I think, be divided into two main groups. A. What (2) asserts is, with regard to a whole set of classes of propositions, that we have, each of us, frequently known to be true propositions belonging to each of these classes. And one way of holding a view incompatible with this proposition is, of course, to hold, with regard to one or more of the classes in question, that no propositions of that class are true - that all of them are, at least partially, false; since if, in the case of any one of these classes, no propositions of that class are true, it is obvious that nobody can have known any propositions of that class to be true, and therefore that we cannot have known to be true propositions belonging to each of these classes. And my first group of philosophers consists of philosophers who have held views incompatible with (2) for this reason. They have held, with regard to one or more of the classes in question, simply that no propositions of that class are true. Some of them have held this with regard to all the classes in question; some only with regard to some of them. But, of course, whichever of these two views they have held, they have been holding a view inconsistent with (2). B. Some philosophers, on the other hand, have not ventured to assert, with regard to any of the classes in (2), that no propositions of that class are true, but what they have asserted is that, in the case of some of these classes, no human being has ever known, with certainty, that any propositions of the class in question are true. That is to say, they differ profoundly from philosophers of group A, in that they hold that propositions of all these classes may be true; but nevertheless they hold a view incompatible with (2) since they hold, with regard to some of these classes, that none of us has ever known a proposition of the class in question to be true.
A. I said that some philosophers, belonging to this group, have held that no propositions belonging to any of the classes in (2) are wholly true, while others have only held this with regard to some of the classes in (2). And I think the chief division of this kind has been the following. Some of the propositions in (1) (and, therefore, of course, all propositions belonging to the corresponding classes in (2)) are propositions which cannot be true, unless some material things have existed and have stood in
A DEFENCE OF COMMON SENSE
spatial relations to one another: that is to say, they are propositions which, in a certain sense, imply the reality of material things, and the reality of Space. E.g., the proposition that my body has existed for many years past, and has, at every moment during that time been either in contact with or not far from the earth, is a proposition which implies both the reality of material things (provided you use 'material things' in such a sense that to deny the reality of material things implies that no proposition which asserts that human bodies have existed, or that the earth has existed, is wholly true) and also the reality of Space (provided, again, that you use 'Space' in such a sense that to deny the reality of Space implies that no proposition which asserts that anything has ever been in contact with or at a distance from another, in the familiar senses pointed out in (1), is wholly true). But others among the propositions in (1) (and, therefore, propositions belonging to the corresponding classes in (2)), do not (at least obviously) imply either the reality of material things or the reality of Space: e.g., the propositions that I have often had dreams, and have had many different feelings at different times. It is true that propositions of this second class do imply one thing which is also implied by all propositions of the first, namely that (in a certain sense) Time is real, and imply also one thing not implied by propositions of the first class, namely that (in a certain sense) at least one Self is real. But I think there are some philosophers, who, while denying that (in the senses in question) either material things or Space are real, have been willing to admit that Selves and Time are real, in the sense required. Other philosophers, on the other hand, have used the expression Time is not real', to express some view that they held; and some, at least, of these have, I think, meant by this expression something which is incompatible with the truth of any of the propositions in (1) - they have meant, namely, that every proposition of the sort that is expressed by the use of 'now7 or 'at present, e.g., 'I am now both seeing and hearing' or These exists at present a living human body', or by the use of a past tense, e.g., 'I have had many experiences in the past, or 'The earth has existed for many years', are, at least partially, false.
All the four expressions I have just introduced, namely 'Material things are not real', 'Space is not real', Time is not real', The Self is not real', are, I think, unlike the expressions I used in (1), really ambiguous. And it may be that, in the case of each of
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them, some philosopher has used the expression in question to express some view he held which was not incompatible with (2). With such philosophers, if there are any, I am not, of course, at present concerned. But it seems to me that the most natural and proper usage of each of these expressions is a usage in which it does express a view incompatible with (2); and, in the case of each of them, some philosophers have, I think, really used the expression in question to express such a view. All such philosophers have, therefore, been holding a view incompatible with
All such views, whether incompatible with all of the propositions in (1), or only with some of them, seem to me to be quite certainly false; and I think the following points are specially deserving of notice with regard to them.
(a) If any of the classes of propositions in (2) is such that no proposition of that class is true, then no philosopher has ever existed, and therefore none can ever have held with regard to any such class, that no proposition belonging to it is true. In other words, the proposition that some propositions belonging to each of these classes are true is a proposition which has the peculiarity, that, if any philosopher has ever denied it, it follows from the fact that he has denied it, that he must have been wrong in denying it. For when I speak of 'philosophers' I mean, of course (as we all do), exclusively philosophers who have been human beings, with human bodies that have lived upon the earth, and who have at different times had many different experiences. If, therefore, there have been any philosophers, there have been human beings of this class; and if there have been human beings of this class, all the rest of what is asserted in (1) is certainly true too. Any view, therefore, incompatible with the proposition that many propositions corresponding to each of the propositions in (1) are true, can only be true, on the hypothesis that no philosopher has ever held any such view. It follows, therefore, that, in considering whether this proposition is true, I cannot consistently regard the fact that many philosophers, whom I respect, have, to the best of my belief, held views incompatible with it, as having any weight at all against it. Since, if I know that they have held such views, I am, ipso facto, knowing that they were mistaken; and, if I have no reason to believe that the proposition in question is true, I have still less reason to believe that they have held views incompatible with it;
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since I am more certain that they have existed and held some views, i.e., that the proposition in question is true, than that they have held any views incompatible with it.
It is, of course, the case that all philosophers who have held such views have repeatedly, even in their philosophical works, expressed other views inconsistent with them: i.e., no philosopher has ever been able to hold such views consistently. One way in which they have betrayed this inconsistency, is by alluding to the existence of other philosophers. Another way is by alluding to the existence of the human race, and in particular by using 'we' in the sense in which I have already constantly used it, in which any philosopher who asserts that 'we' do so and so, e.g., that 'we sometimes believe propositions that are not true', is asserting not only that he himself has done the thing in question, but that very many other human beings, who have had bodies and lived upon the earth, have done the same. The fact is, of course, that all philosophers have belonged to the class of human beings which exists only if (2) be true: that is to say, to the class of human beings who have frequently known prop- ositions corresponding to each of the propositions in (1). In holding views incompatible with the proposition that propositions of all these classes are true, they have, therefore, been holding views inconsistent with propositions which they them selves knew to be true; and it was, therefore, only to be expected that they should sometimes betray their knowledge of such propositions. The strange thing is that philosophers should have been able to hold sincerely, as part of their philosophical creed, propositions inconsistent with what they themselves knew to be true; and yet, so far as I can make out, this has really frequently happened. My position, therefore, on this first point, differs from that of philosophers belonging to this group A, not in that I hold anything which they don't hold, but only in that I don't hold, as part of my philosophical creed, things which they do hold as part of theirs - that is to say, propositions inconsistent with some which they and I both hold in common. But this difference seems to me to be an important one.
Some of these philosophers have brought forward, in favour of their position, arguments designed to show, in the case of some or all of the propositions in (1), that no propositions of that type can possibly be wholly true, because every such proposition entails both of two incompatible propositions.