Philosophical Studies · G. E. Moore
THE NATURE AND REALITY OF OBJECTS OF PERCEPTION
There are two beliefs in which almost all philosophers, and almost all ordinary people are agreed. Almost everyone believes that he himself and what he directly perceives do not constitute the whole of reality: he believes that _something_ other than himself and what he directly perceives _exists_ or is _real._ I do not mean to say that almost everyone believes that what he directly perceives is real: I only mean that he does believe that, whether what he directly perceives is real or not, something other than it and other than himself certainly is so. And not only does each of us thus agree in believing that _something_ other than himself and what he directly perceives is real: almost everyone also believes that _among_ the real things, other than himself and what he directly perceives, are other persons who have thoughts and perceptions in some respects similar to his own. That most people believe this I think I need scarcely try to show. But since a good many philosophers may appear to have held views contradictory of this one, I will briefly point out my reason for asserting that most philosophers, even among those (if any) who have believed the contradictory of this, have yet held this as well.
Almost all philosophers tell us something about the nature of _human_ knowledge and _human_ perception. They tell us that _we_ perceive so and so; that the nature or origin of _our_ perceptions is such and such; or (as I have just been telling you) that men in general have such and such beliefs. It might, indeed, be said that we are not to interpret such language too strictly: that, though a philosopher talks about _human_ knowledge and _our_ perceptions, he only means to talk about his own. But in many cases a philosopher will leave no doubt upon this point, by expressly assuming that there are other perceptions, which differ in some respects from his own: such, for instance, is the case when (as is so common nowadays) a philosopher introduces psycho-genetic considerations into his arguments --considerations concerning the nature of the perceptions of men who existed before and at a much lower stage of culture than himself. Any philosopher, who uses such arguments, obviously assumes that perceptions other than his own have existed or been real. And even those philosophers who think themselves justified in the conclusion that neither their own perceptions nor any perceptions like theirs are _ultimately_ real, would, I think admit, that _phenomenally_, at least, they _are_ real, and are certainly _more_ real than some other things.
Almost everyone, then, does believe that some perceptions other than his own, and which he himself does not directly perceive, are real; and believing this, he believes that something other than himself and what he directly perceives is real. But how do we know that anything exists except our own perceptions, and what we directly perceive? How do we know that there are any other people, who have perceptions in some respects similar to our own? I believe that these two questions express very exactly the nature of the problem which it is my chief object, in this paper, to discuss. When I say these words to you, they will at once suggest to your minds the very question, to which I desire to find an answer; they will convey to you the very same meaning which I have before my mind, when I use the words. You will understand at once what question it is that I mean to ask. But, for all that, the words which I have used are highly ambiguous. If you begin to ask yourselves what I do mean by them, you will find that there are several quite different things which I might mean. And there is, I think, great danger of confusing these different meanings with one another. I think that philosophers, when they have asked this question in one sense, have often answered it in quite a different sense; and yet have supposed that the answer which they have given is an answer to the very same question which they originally asked. It is precisely because there is this ambiguity--this danger of confusion, in the words which I have used, that I have chosen to use them. I wish to point out as clearly as I can, not only what I do mean by them, but also some things which I do _not_ mean; and I wish to make it clear that the questions which I do _not_ mean to ask, are different questions from that which I do mean to ask.
I will take the second of my two questions, since there is in the other an additional ambiguity to which I do not now wish to call attention. My second question was: How do we know that there exist any other people who have perceptions in some respects similar to our own? What does this question mean? Now I think you may have noticed that when you make a statement to another person, and he answers "How do you know that that is so?" he very often means to suggest that you do _not_ know it. And yet, though he means to suggest that you do not _know_ it, he may not for a moment wish to suggest that you do not _believe_ it, nor even that you have not that degree or kind of conviction, which goes beyond mere belief, and which may be taken to be essential to anything which can properly be called knowledge. He does not mean to suggest for a moment that you are saying something which you do not believe to be true, or even that you are not thoroughly convinced of its truth. What he does mean to suggest is that what you asserted was not _true_, even though you may not only have believed it but felt sure that it was true. He suggests that you don't _know_ it, in the sense that what you believe or feel sure of is not true.
"How does our belief in their existence arise?" But if I do not mean this what do I mean P I have said that I mean to ask a question with regard to the _truth_ of that belief; and the particular question which I mean to ask might be expressed in the words: _What reason have_ we for our belief in the existence of other persons? But these are words which themselves need some explanation, and I will try to give it. In the first place, then, when I talk of "a reason," I mean _only_ a good reason and _not_ a bad one. A bad reason is, no doubt, a reason, in one sense of the word; but I mean to use the word "reason" exclusively in the sense in which it is equivalent to "good reason." But what, then, is meant by a good reason for a belief? I think I can express sufficiently accurately what I mean by it in this connection, as follows:--A good reason for a belief is a proposition which is true, and which would not be true unless the belief were also true. We should, I think, commonly say that when a man knows such a proposition, he has a good reason for his belief; and, when he knows no such proposition, we should say that he has no reason for it. When he knows such a proposition, we should say he knows something which is a reason for thinking his belief to be true--something from which it _could_ be validly inferred. And if, in answer to the question "How do you know so and so?" he were to state such a proposition, we should, I think, feel that he had answered the question which we meant to ask.
Suppose, for instance, in answer to the question "How do you know that?" he were to say "I saw it in the _Times."_ Then, if we believed that he had seen it in the _Times_, and also believed that it would not have been in the _Times_, unless it had been true, we should admit that he had answered our question. We should no longer doubt that he did _know_ what he asserted, we should no longer doubt that his belief was true. But if, on the other hand, we believed that he had not seen it in the _Times_--if, for instance, we had reason to believe that what he saw was not the statement which he made, but some other statement which he mistook for it; or if we believed that the kind of statement in question was one with regard to which there was no presumption that, being in the _Times_, it would be true: in _either_ of these cases we should, I think, feel that he had _not_ answered our question. We should still doubt whether what he had said was true.
We should still doubt whether he _knew_ what he asserted; and since a man cannot tell you how he _knows_ a thing unless he does know that thing, we should think that, though he might have told us truly how he _came to believe it,_ he had certainly not told us how he _knew_ it. But though we should thus hold that he had _not_ told us _how he knew_ what he had asserted, and that he had given us no reason for believing it to be true; we must yet admit that he had given us a reason in a sense--a _bad_ reason, a reason which was no reason because it had no tendency to show that what he believed was true; and we might also be perfectly convinced that he had given us _the reason_ why he believed it--the proposition by believing which he was induced also to believe his original assertion.
I mean, then, by my question, "How do we know that other people exist?" what, I believe, is ordinarily meant, namely, "What reason have we for believing that they exist?" and by this again I mean, what I also believe is ordinarily meant, namely, "What proposition do we believe, which is both true itself and is also such that it would not be true, unless other people existed?" And I hope it is plain that this question, thus explained, is quite a different question from the psychological question, which I said I did _not_ mean to ask--from the question, "How does our belief in the existence of other people arise?" My illustration, I hope, has made this plain. For I have pointed out that we may quite well hold that a man has told us how a belief of his arises, and even what was the reason which made him adopt that belief, and yet may have failed to give us any _good reason_ for his belief--any proposition which is both true itself, and also such that the truth of his belief follows from it.
And, indeed, it is plain that if any one ever believes what is false, he is believing something for which there _is_ no good reason, in the sense which I have explained, and for which, therefore, he cannot possibly have a good reason; and yet it plainly does not follow that his belief did not arise in anyway whatever, nor even that he had no reason for it--no bad reason. It is plain that false beliefs do arise in some way or other--they have origins and causes: and many people who hold them _have_ bad reasons for holding them--their belief does arise (by inference or otherwise) from their belief in some other proposition, which is not itself true, or else is not a _good_ reason for holding that, which they infer from it, or which, in some other way, it induces them to believe. I submit, therefore, that the question, "What good reason have we for believing in the existence of other people?" is different from the question, "How does that belief arise?" But when I say this, I must not be misunderstood; I must not be understood to affirm that the answer to both questions _may_ not, in a sense, be the same.
I fully admit that the very same fact, which suggests to us the belief in the existence of other people, _may_ also be a good reason for believing that they do exist. All that I maintain is that the question whether it is a good reason for that belief is a different question from the question whether it suggests that belief: if we assert that a certain fact _both_ suggests our belief in the existence of other persons and is _also_ a good reason for holding that belief, we are asserting two different things and not one only. And hence, when I assert, as I shall assert, that we _have_ a good reason for our belief in the existence of other persons, I must not be understood also to assert either that we infer the existence of other persons from this good reason, or that our belief in that good reason suggests our belief in the existence of other persons in any other way. It is plain, I think, that a man may believe two true propositions, of which the one would not be true, unless the other were true too, without, in any sense whatever, having arrived at his belief in the one _from_ his belief in the other; and it is plain, at all events, that the question whether his belief in the one _did_ arise from his belief in the other, is a different question from the question whether the truth of the one belief follows from the truth of the other.
I hope, then, that I have made it a little clearer what I mean by the question: "What reason have we for believing in the existence of other people?" and that what I mean by it is at all events different from what is meant by the question: "How does our belief in the existence of other people arise?" But I am sorry to say that I have not yet reached the end of my explanations as to what my meaning is. I am afraid that the subject may seem very tedious. I can assure you that I have found it excessively tedious to try to make my meaning clear to myself. I have constantly found that I was confusing one question with another, and that, where I had thought I had a good reason for some assertion, I had in reality no good reason. But I may perhaps remind you that this question, "How do we know so and so?" "What reason have we for believing it?" is one of which philosophy is full; and one to which the most various answers have been given. Philosophy largely consists in giving reasons; and the question what are good reasons for a particular conclusion and what are bad, is one upon which philosophers have disagreed as much as on any other question. For one and the same conclusion different philosophers have given not only different, but incompatible, reasons; and conversely different philosophers have maintained that one and the same fact is a reason for incompatible conclusions. We are apt, I think, sometimes to pay too little attention to this fact.
When we have taken, perhaps, no little pains to assure ourselves that our own reasoning is correct, and especially when we know that a great many other philosophers agree with us, we are apt to assume that the arguments of those philosophers, who have come to a contradictory conclusion, are scarcely worthy of serious consideration. And yet, I think, there is scarcely a single reasoned conclusion in philosophy, as to which we shall not find that some other philosopher, who has, so far as we know, bestowed equal pains on his reasoning, and with equal ability, has reached a conclusion incompatible with ours. We may be satisfied that we are right, and we may, in fact, be so; but it is certain that _both_ cannot be right: either our opponent or we must have mistaken bad reasons for good. And this being so, however satisfied we may be that it is not we who have done so, I think we should at least draw the conclusion that it is by no means easy to avoid mistaking bad reasons for good; and that no process, however laborious, which is in the least likely to help us in avoiding this should be evaded.
But it is at least possible that one source of error lies in mistaking one kind of reason for another--in supposing that, because there is, in one sense, a reason for a given conclusion, there is also a reason in another, or that because there is, in one sense, no reason for a given conclusion, there is, therefore, no reason at all. I believe myself that this _is_ a very frequent source of error: but it is at least a possible one. And where, as disagreements show, there certainly is error on one side or the other, and reason, too, to suppose that the error is not easy to detect, I think we should spare no pains in investigating any source, from which it is even possible that the error may arise. For these reasons I think I am perhaps doing right in trying to explain as clearly as possible not only what reasons we have for believing in an external world, but also in what sense I take them to be reasons.
I proceed, then with my explanation. And there is one thing, which, I think my illustration has shown that I do _not_ mean. I have defined a reason for a belief as a true proposition, which would not be true unless the belief itself--what is believed--were also true; and I have used, as synonymous with this form of words, the expressions: A reason for a belief is a true proposition from which the truth of the belief _follows_ from which it _could_ be _validly inferred._ Now these expressions might suggest the idea that I mean to restrict the word "reason," to what, in the strictest sense, might be called a _logical_ reason--to propositions from which the belief in question _follows,_ according to the rules of inference accepted by Formal Logic. But I am _not_ using the words "follow," "validly inferred," in this narrow sense; I do _not_ mean to restrict the words "reason for a belief" to propositions from which the laws of Formal Logic state that the belief could be deduced. The illustration which I gave is inconsistent with this restricted meaning. I said that the fact that a statement appeared in the _Times_ might be a good reason for believing that that statement was true.
And I am using the word "reason" in the wide and popular sense, in which it really might be. If, for instance, the _Times_ stated that the King was dead, we should think that was a good reason for believing that the King was dead; we should think that the _Times_ would not have made such a statement as that unless the King really were dead. We should, indeed, not think that the statement in the _Times_ rendered it absolutely _certain_ that the King was dead. But it _is_ extremely unlikely that the _Times_ would make a statement of this kind unless it were true; and, in that sense, the fact of the statement appearing in the _Times_ would render it _highly probable_--much more likely than not--that the King was dead. And I wish it to be understood that I am using the words "reason for a belief" in this extremely wide sense. When I look for a good reason for our belief in the existence of other people, I shall not reject any proposition merely on the ground that it only renders their existence probable--only shows it to be more likely than not that they exist. Provided that the proposition in question does render it _positively probable_ that they exist, then, if it also conforms to the conditions which I am about to mention, I shall call it a "good reason."
But it is not every proposition which renders it probable that other people exist, which I shall consider to be a good answer to my question. I have just explained that my meaning is wide in one direction--in admitting _some_ propositions which render a belief merely probable; but I have now to explain that it is restricted in two other directions. I do mean to exclude certain propositions which do render that belief probable. When I ask: What reason have _we_ for believing in the existence of other people? a certain ambiguity is introduced by the use of the plural "we." If each of several different persons has a reason for believing that he himself exists, then it is not merely probable, but certain, according to the rules of Formal Logic, that, in a sense, _they_ "have a reason for believing" that several people exist; each has a reason for believing that he himself exists; and, therefore, all of them, taken together, have reasons for supposing that several persons exist.
If, therefore, I were asking the question: What reason have _we_ for believing in the existence of other persons? in this sense, it would follow that if each of us has a reason for believing in his own existence, these reasons, taken together, would be a reason for believing in the existence of all of us. But I am not asking the question in this sense: it is plain that this is not its natural sense. What I do mean to ask is: Does _each single one_ of us know any proposition, which is a reason for believing that _others_ exist? I am using "we," that is to say, in the sense of "each of us." But again I do mean _each_ of us: I am not merely asking whether some _one_ man knows a proposition which is a reason for believing that other men exist. It would be possible that some one man, or some few men, should know such a proposition, and yet the rest know no such proposition. But I am not asking whether this is the case. I am asking whether among propositions of the kind which (as we commonly suppose) all or almost all men know, there is any which is a reason for supposing that other men exist.
And in asking this question I am not begging the question by supposing that all men do exist. My question might, I think, be put quite accurately as follows. There are certain kinds of belief which, as we commonly suppose, all or almost all men share. I describe this kind of belief as "our" beliefs, simply as an easy way of pointing out which kind of belief I mean, but without assuming that all men do share them. And I then ask: Supposing a single man to have beliefs of this kind, which among them would be a good reason for supposing that other men existed having like beliefs? This, then, is the first restriction which I put upon the meaning of my question. And it is, I think, a restriction which, in their natural meaning, the words suggest. When we ask: What reason have we for believing that other people exist? we naturally understand that question to be equivalent to: What reason has _each_ of us for that belief? And this question again is naturally equivalent to the question: Which among the propositions that a single man believes, but which are of the kind which (rightly or wrongly) we assume all men to believe, are such that they would not be true unless some other person than that man existed? But there is another restriction which, I think, the words of my question also naturally suggest. If we were to ask anyone the question: How do you know that you did see that statement in the _Times_? and he were to answer "Because I did see it in the _Times_ and in the _Standard_ too," we should not think that he had given us a _reason_ for the belief that he saw it in the _Times._ We should not think his answer a _reason_, because it asserts the very thing for which we require a reason.
Ideas discussed in this chapter
Text from Project Gutenberg, public domain in the United States.